UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

A kinetic study of the addition of the ethyl radical to acrylonitrile and its mono-methyl derivatives Ogawa, Takeshi 1962

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1963_A6_7_O3 K4.pdf [ 5.09MB ]
Metadata
JSON: 831-1.0061949.json
JSON-LD: 831-1.0061949-ld.json
RDF/XML (Pretty): 831-1.0061949-rdf.xml
RDF/JSON: 831-1.0061949-rdf.json
Turtle: 831-1.0061949-turtle.txt
N-Triples: 831-1.0061949-rdf-ntriples.txt
Original Record: 831-1.0061949-source.json
Full Text
831-1.0061949-fulltext.txt
Citation
831-1.0061949.ris

Full Text

A KINETIC STUDY OF THE ADDITION OF THE ETHYL RADICAL TO ACRYLONITRILE AND ITS MONO-METHYL DERIVATIVES by TAKESHI OGAWA S .A .Sc . The Kyushu Un ive r s i t y , 1957 A thesis submitted i n p a r t i a l fu l f i lmen t of the requirements for the degree of MASTER OF SCIENCE, i n the Department of CHEMISTRY We accept th i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA November9 1962 In presenting t h i s t h e s i s i n p a r t i a l f u l f i l m e n t of the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree that permission f o r extensive copying of t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s representatives. It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of Chemistry The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. Date 20 November, 1962. 11 ABSTRACT The k i n e t i c s tudy o f the r e a c t i o n s , o f the e t h y l r a d i c a l w i t h the conjugated o l e f i n i c compounds has revea led the e f f e c t . o f v a r i o u s s t r u c t u a l f a c t o r s upon m o l e c u l a r r e a c t i v i t y . A c r y l o h i t r i i e and i t s mono-methyl d e r i v a t i v e s ; c i s - and t r a n s -c r o t o n o n i t r i l e and m e t h a c r y l o n i t r i l e were the subs t ra te s i n t h i s i n v e s t i g a t i o n . I t was found t h a t the a d d i t i o n o f the e t h y l r a d i c a l to the 0=0 double bond was the most important r e a c t i o n and t h a t methathesis and a d d i t i o n to ther ON t r i p l e bond cou ld be neg-l e c t e d Values f o r the energy o f a c t i v a t i o n (E^- lEg) f o r e l s - and t r a n s - c r o t o n o n i t r i l e and m e t h a c r y l o n i t r i l e were not d i s t i n g u i s h a b l e ; 4 .85 * 0 . 6 8 , 4.69 ± 0 . 9 6 and 4.61 ± 0 . 6 7 r e s p e c t i v e l y . The energy of a c t i v a t i o n f o r a c r y l o n i t r i l e f o r a c r y l o n i t r l l e was found to be 3.45 * 0 . 5 2 . I t appeared t h a t the methyl group I n c i s - and t r a n s - o r o t o n o n i t r l l e and i n metha-c r y l o n i t r i l e r a i s e d the energy of a c t i v a t i o n f o r a d d i t i o n from the va lue f o r a c r y l o n i t r l l e by about the same amount f o r each of the methyl d e r i v a t i v e s . Simple c o r r e l a t i o n s o f the r a t e constants f o r the a d d i t i o n of the e t h y l r a d i c a l w i t h the methyl a f f i n i t i e s w i t h v a r i o u s s u b s t r a t e s , and w i t h the monomer r e a c t i v i t y r a t i o s f o r the c o p o l y m e r i z a t i o n o f v a r i o u s monomers w i t h s tyrene were o b t a i n e d . C o p o l y m e r i z a t l o n r e a c t i o n s o f c i s - and t r a n s - c r o t o n o n i t r i l e w i t h s tyrene are a l s o i n v e s t i g a t e d and the p o l i m e r l z a b i l i t y of these compounds i s d i s c u s s e d . Some s t u d i e s on the i s o m e r i z a t i o n of c i s - and t r a n s -i i i c r o t o n o n i t r i l e are also discussed. In t h i s work, e i s - c r o t o -n q n i t r i l e was found to be thermally more stable than the trans isomer. Iv TABLE OF CONTENTS INTRODUCTION©.© ©'© © © .© © ©-.© ©. © • • o o, © o « o o o © .© * © > © • © ' > © © © © © • « , ©' © © o © • 1 G e n e r a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 The reaat ive r e a c t i v i t y of o l e f i n l c double bond towards free r a d i c a l s . . . . . . . . . . . . . . . . . . . . . . . .6 The k i n e t i c s of the reactions of the e thyl r a d i c a l 7 O o p o l y m e r i z a t i o n . . . . . . . . . . . . . . . . . . . . . . . > . . . . . • . . 1 0 c i s - t rans I s o m e r l z a t l o n . . . . . . . . . . . . . . . . . . 1 2 The scope of t h i s i n v e s t i g a t i o n . . . . . . . . . . . . . . . . . 1 3 EXPERIMENTALS M a t e r i a l s . . . . . . . . . . . . . . . . . . . . . . . - . . . . . . . . . . . . . . . . 1 5 Apparatus and analys is for gas phase reac t ions . .16 O o p o l y m e r i z a t i o n . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . .18 I sbmer lza t lon . . • . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . 1 9 RESULTS.. . . . . . . . . . . . . ... . . . . . . . . . . . . . . . . . . . . > . . . . . . . , . . . .20 Reactions of the e thy l r a d i c a l w i t h subst ra tes . . .21 Copolymer iza t lon . . . . o . « . . . . . . . . . . . . . . . . . . . . . - . . . . . 36 I s o m e r l z a t i o n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 DISCUSSIONS Reactions of the e thyl r a d i c a l wi th a c e t o n i t r i l e 38 . Reactions of the e thyl r a d i c a l wi th c i s - and t r a n s - c r o t o n o n i t r i l e . . . . . . . . . . . . . . . . . . . . 4 3 Reactions of the e thyl r a d i c a l wi th a c r y l o n i t r i l e and m e t h a c r y l o n i t r l l e . . . . . . . . . . . . . .49 V Rela t ive r e a c t i v i t y and pattern of s u b s t i t u t i o n . . . 5 2 * 3 A 2 . . . . . . . . . . . . . . . . . . . . . . , . . . . . . , . . .55 Absolute values ofE„ and A _ . . . . .57 Cor re l a t ion between values of k ^ / k | and of methyl a f f i n i t y . . . . . . ....57 The p o l y s t y r y l r a d i c a l . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1 Gopolymerization of crotononitrile................ .67 Isomerizat ion of c i s - and t rans-c ro tononi t r i l e . ...76 CONCLUSION............................................. .81 REFERENCES............................................. 82 v i LIST OF TABLES 1. Reac t ions of the e t h y l r a d i c a l w i t h a c e t o n i t r i l e . . . . . 2 1 .2. Reac t ions of the e t h y l r a d i c a l w i t h cis "•cro'toiioiii'trJLX© • ; • > - © • a o . o « • o « < > / • • © * • • • • . © © • © • o • • © , © • © © 2 2 3 . Reac t ions of the e t h y l r a d i c a l w i t h t r a n s — c r o t o n o n i t r i l e « o . . . . . • . . . . • • • • • . . . . . . . . . . . . . .24 4 . Reac t ions of the e t h y l r a d i c a l w i t h m e t h a c r y l o n i t r i l e . 2 6 5 . Reac t ions of the e t h y l r a d i c a l w i t h a c r y l o n i t r l l e . . . . 2 8 6 . C o p o l y m e r i z a t i o n of c r o t o n o n i t r i l e w i t h s t y r e n e . . . . . . . 3 1 7 . c i s - t r a n s I s o m e r i z a t i o n s r e a c t i o n s of c r o t o n o n i t r i l e . . 3 6 8. A d d i t i o n o f the e t h y l r a d i c a l to a c e t o n i t r i l e . . . . . . . . 4 l 9 . A b s t r a c t i o n of the hydrogen atom from a c e t o n i t r i l e . . . 4 2 10 . R a d i c a l r e a c t i v i t i e s o f c i s and t r ans i s o m e r s . . . . . . . . . 4 7 1 1 . C o r r e l a t i o n of the r a t e constants f o r the a d d i t i o n of the e t h y l r a d i c a l w i t h the methyl a f f i n i t i e s o f v a r i o u s s u b s t r a t e s . . . . . . . . . . . . . . . . . • . . . . . . . . . . . . . . .59 12 . C o r r e l a t i o n between the r a t e constants f o r the a d d i t i o n o f the e t h y l r a d i c a l and the monomer r e a c t i v i t y r a t i o s . . . . . . . . . . . . . . . . . . . . . . . . • . . . . . . . . .-...65 13 . C o p o l y m e r i z a t i o n o f 1 . 2 - d l s u b s t i t u t e d e t h y l e n e s . . . . . . 7 1 14. C o p o l y m e r i z a t l o n of c t o t o n o n i t r i l e w i t h v a r i o u s m o n o m e r s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 v i i LIST OF FIGURES F i g u r e 1. A d d i t i o n o f the e t h y l r a d i c a l to c i s - andtrans c r o t o n o n l t r i l e * » » > •/ • • • > • v« • •• • • • • ©» • ••• » • .29 2. A d d i t i o n o f the etjayl r a d i c a l *jto a c r y l o n i t r l l e and m e t h a c r y l o n i t r i l e • • • • • , . . . . • . . « . . • • • • •:••>3P 3. C o p o l y m e r i z a t i o n o f c r o t o n o n i t r i l e w i t h s tyrene . . ..32 4. c l s - t r a n s I spmerizat io iL- of c r o t o n o n i t r i l e i n the l i q u i d $hase i n the presence o f d i e t h y l ketone o © © © •35 5. C o r r e l a t i o n of the r a t e constants f o r the a d d i t i o n o f the e t h y l r a d i c a l w i t h the methyl a f f i n i t i e s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60 6. C o r r e l a t i o n o f the r a t e constants f o r the a d d i t i o n of the e t h y l r a d i c a l w i t h the monomer r e a c t i v i t y ratios.... ................................ v.. •.-.'•..>.. 66 7. A d d i t i o n o f a. polymer r a d i c a l to 1,2 -d l suhs t l tu ted v i i i ACKNOWLEDGEMENTS I w i s h to thank D r . D. G. L . James f o r h i s guidance and encouragement i n the course of t h i s i n v e s t i g a t i o n . INTRODUCTION The Inves t iga t ion of react ions of free r ad ica l s wi th organic compounds const i tutes a s i g n i f i c a n t proportion of k i n e t i c studies both i n the gas and In the l i q u i d phase. In p a r t i c u l a r , the add i t ion of free r a d i c a l to the 0=0 double bond has proved to be an important f i e l d of I n -v e s t i g a t i p n . Those react ions have not only supplied k i n e t i c data, but have a lso been important i n extending our knowledge of the chemistry of o l e f i n l c compounds. For a long time experimental d i f f i c u l t i e s i n product analys is retarded the progress of k i n e t i c s tudies; ,how-ever 9 i n recent years, the employment of a more rapid gas chromatography has made a possible advance i n t h i s f i e l d . In general , react ions of addi t ion of a free r a d i c a l to an o l e f i n may be represented by the fo l lowing general scheme: I n i t i a t i o n E." +. XY —^ R*X + Y« ( la) or XY —z> X» + Y- ( lb) Propagation Y* + R0H=0H2 ROHOHgY (2) ROHCHgY + XY —ROHXOHgY + Y»(3a) or ROHOHgY + X« —^ R0HX0H2Y (3b) Thus the chain-propagation reac t ion consists of two steps % (I) an add i t ion step, reac t ion (2) , and ( i i ) a r a d i c a l displacement step, (3a) or a termination step, (3b). In most (> / cases the rate constant for add i t ion reac t ion can be obtained experimentally i n the form ofarat io wi th the rate constant of the competing r eac t ion . In many works, free r ad i ca l s used have been produced by thermal decomposition of organic peroxides, photolysis of ketones, azo compounds or peroxide, and i n some cases, r a d i o l y s l s of compounds wi th X-rays or ^T-rays. T. J . Hardwick ( l ) (2 ) has studied the reac t ion of hydrogen atoms wi th a ser ies of o l e f l n l c compounds i n n -hexane, and i t was found that both add i t ion and abstrac-t i o n of hydrogen occurred, and that the r e a c t i v i t y of hydrogen atoms was s i m i l a r to that of a l k y l r a d i c a l s . For o le f ins wi th given s t ruc tu ra l type, e . g . , RCH=sGHR, the rate constants of the react ions were the same, a l -though these rate constants var ied from one s t ruc tua l type to another. The rate constants for the addi t ion of hydrogen atoms stood In the orders R 20=0H 2 > R0H=CH2 > RgOsOHR > RCHsCHR > R 20=0R 2 . In the gas phase, Jennings and Gvetanovic (3) have a lso inves t igated the r e l a t i v e rates of add i t ion of hydrogen atoms to o l e f i n s . Hydrogen atoms were produced by the mercury-photosensitized .decomposition, of n-butane at 435-5 mm pressure and at 23.5±1 °G. They obtained r e l a t i v e rates of add i t ion to various o l e f i n s , e . g . , ethylene, butene, propylene e t c . , i n such a way that , by Introducing known amounts of - 3 -o l e f i n , the r a t e o f a d d i t i o n of hydrogen atoms to the o l e f i n could be measured r e l a t i v e to the r a t e of a b s t r a c -t i o n from the n-butane by observ ing the f a l l I n the r a t e of p r o d u c t i o n of hydrogen. T h e i r r e s u l t s showed t h a t there e x i s t e d a f a i r l y good c o r r e l a t i o n between the r a t e constants o f a d d i t i o n r e a c t i o n s and the atom l o c a l i z a t i o n energies f o r the m p n o - o l e f i n s . R e a c t i o n s . o f polyhalogeno a l k y l r a d i c a l s w i t h o l e f i n s were I n v e s t i g a t e d by many worker s . Jensen, Kharasch and Urry (4) r e p o r t e d t h a t carbon t e t r a c h l o r i d e and ch loro form r e a c t e d w i t h octane-1 by way of a r a d i c a l c h a i n t o g i v e 1,1,1,3-tetrachlorononane and 1,1,1 - t r l c h l o r o n o n a n e , r e -s p e c t i v e l y , e . g . •001 5 + ROHsGHg — > R0H0H 2001 3 R0H0H 2001 3 + 0H01 3 —^ > R q H 20H 2001 5 + • O O l j L a t e r , i t was shown t h a t carbon te t rabromide (5) and bromoform, (6) a l s o r e a c t e d a d d i t i v e l y w i t h o l e f i n s con-t a i n i n g a t e r m i n a l double bonds (pctane-1, s t y r e n e , e t h y l a c r y l a t e , d i a l l y l , propylene) under the I n f l u e n c e of added perox ides o r l i g h t o f s u i t a b l e wave l e n g t h . Szwarc , S t e f a n l and Herk have s t u d i e d the k i n e t i c s o f a d d i t i o n of the t r i f l u o r o m e f h y l r a d i c a l to v a r i o u s o l e f i n i e compounds (7). The t r i f l u o r o m e t h y l r a d i c a l was generated by the p h o t o l y s i s o f hexafluoroazomethane i n I so-octane s o l u t i o n a t 65°C. R e l a t i v e r a t e s o f a d d i t i o n of OF3 r a d i c a l to o l e f i n s were obtained as the r a t i o with the competing reaction (abstraction of hydrogen from iso.» o ctane)• Reactions of the methyl r a d i c a l with a great number of compounds having unsaturated bonds were investigated by Szwarc and his co-workers (8) to (16). The methyl r a d i c a l was produced by the thermal decomposition of ace-t y l peroxide i n iso=octane s o l u t i o n . They determined experimentally the r a t i o of kg/k^ where kg and k^ are the rate, constants of the Investigated process; kg Ri R i • 0—0 R 4 0H 4 + 0 8 H ^ then ( the amount of OHi, l o s t ) X , , „ .2' ^ 1 ( the amount of O H ^ formed ) X Q Q where "the amount of OH^ formed" i s the amount of methane ac t u a l l y formed i n the reaction, "amount of O H ^ l o s t " i s the difference between the amount of GH^ formed i n the absence of an unsaturated compound and i n i t s presence„ and X - „ / X _ - i s the molar r a t i o of i s o-octane, to the unsatura-ted compound i n the solution. The reaction of the ethyl r a d i c a l with series of unsaturated hydrocarbons, were investigated by James and. - 5 -Steaci.e (17)(18). The ethyl r a d i c a l s were generated by the photolysis of d i e t h y l ketone i n gas phase, (the kin e t i c s of the reaction of the ethyl r a d i c a l i s de-scribed i n a l a t e r section). They obtained energies of a c t i v a t i o n and Arrhenius factors f o r addition reactions of ethyl r a d i c a l with l-heptyhej l-heptene, 1-octe.ne, 1-hexene. 2,.4,4..-trimethyl-l-pentene and 2.3i>3-trimethyl-l-butene by measuring the rate constants at various temperatures. They also t r i e d to discuss the r e a c t i v i t y of each substrate i n terms of i t s pattern of s u b s t i t u t i o n at the multiple bond,, and i n p a r t i c u l a r ^ t h e i r r e s u l t s showed that f o r a l l series the r e a c t i v i t y runs i n the sequence; R l /Q=0K2 > R-CH=0H2 » Ri-GH-CH-112. type of s u b s t i t u t i o n James and h i s co-workers have been studying the reaction of the ethyl r a d i c a l with v i n y l monomers (19)9 conjugated dlenes (20), a l l y l compounds (21) and other unsaturated compounds. In every case.- possible correlations have been discussed between r e a c t i v i t y with the ethyl r a d i c a l and with the other r a d i c a l s , polymerizabllity, struptual character of a molecule, etc. - 6 -The r e l a t i v e r e a c t i v i t y of o l e f l n i c double bonds towards free r a d i c a l s . In an examination of the r e l a t i onsh ip between structure and r e a c t i v i t y towards free r a d i c a l add i t i on , the p r i n c i p a l factors appear to bes (a) the degree of s t a b i l i z a t i o n of the medical adduct, (b) s t e r i c hindrance i n the substrate and (c) a polar effect i n the t r a n s i t i o n s ta te . These views are supported by a va r i e ty of experimental observations, (a) Compounds such as styrehe and butadiene, that y i e l d resonance-s tabi l ized r a d i c a l s , are very much more react ive than those which do not . (b) The large differences i n r e -a c t i v i t y between oi and |3- methyl styrenes and between styrene and e thyl cinnamate are also not iceable; t h i s effect has general ly been a t t r ibu ted to s t e r i c hindrance, although the evidence on t h i s point i s l i m i t e d . (c) E l e c t r o n -donating groups i n the o l e f i n increase the r e a c t i v i t y of the rate of the reac t ion ; t h i s behaviour being r e s t r i c t e d to at tack by r ad i ca l s wi th weak electron donating character. Differences i n r e a c t i v i t y between c i s and trans o le f ins have been reported. Szwarc and h is co-workers (12) have im-ade a k i n e t i c study of the addi t ion of the methyl r a d i c a l to Isomeric c i s - and t rans- o le f ins In iso-octane s o l u t i o n . They found that wi th s t i l benes , and also wi th d i e t h y l maleate and fumarate, the thermodynamipally more stable Isomer Is the more r eac t ive . - 7' -The k i n e t i c s of the react ions of the e thyl r a d i c a l . The mechanism for the photolysis of pure d i e t h y l ketone has been proposed by Dorfman and Seldon (22) and confirmed by Kutschke» Wijnen and Steacie (23) 9 Br in ton and Steacie (24) and Weir (25). 0 2 H 5 0 0 0 2 H 5 + hV '—> 2 G 2 H 5 ° + CO ( l ) 2 0 2 H 5 » —^ 0 4 H 1 0 (2) 2 0 2 H 5 ° — ° 2 H 6 + ° 2 H 4 02H5° + 0 2 H 5 0 p 0 2 H 5 —> 02H6 +; •O.gH^ QOO^ - (4) At higher l i g h t i n t e n s i t i e s and below 250°0 the pentanonyl r a d i c a l i s removed from the system by the reac t ion ° 2 H 5 " + ° 0 2 H 4 0 0 0 2 H 5 04H 9 000 2 H 5 (4a) Under.these condi t ions 9 one molecule of carbon monoxide i s equivalent to two e thyl r a d i c a l s a n d hence to one molecule of e i ther ethane or butane. The mater ia l balance may be defined by the r a t i o M -R C O where the symbol Rx represents the rate of formation of the : -1 '-=.3 product X in . molecules s cm of i l lumina ted volume. The quanti ty of M: has been reported as O.988 ± 0.02 by Kutschke and 0.997 * 0.03 by James and Steaeie (17). These values demonstrate that the react ions (1.) to (4a) completely account for a l l the products. - 8 -The r a t i o of k-j/kg has been found by prev ious workers t o be a constant having a va lue of 0.136 (17) . T h i s i s a p p r e c i a b l y h i g h e r than the l i m i t i n g va lue of 0.12 r epor ted by B r i n t o n and S t e a c i e (24) who e x p l a i n e d the h i g h e r va lues on the b a s i s o f a d d i t i o n a l e thylene formed by the thermal decompos i t ion of the pentanonyl r a d i c a l , • C 2 H 4 C 0 C 2 H 5 —> 0 2 H 4 + CO + 0 2 H 5 ' (5) I n the case o f p h o t o l y s i s o f the systems c o n t a i n i n g a hydro-carbon s u b s t r a t e , the a d d i t i o n and a b s t r a c t i o n r e a c t i o n s o f the e t h y l r a d i c a l r e s u l t I n the f o r m a t i o n of r a d i c a l s R' and I t i s p o s s i b l e t h a t a s m a l l f r a c t i o n of these r a d i c a l s y i e l d e thylene i n the r e a c t i o n 0 2 h y + R« — ^ 0 2 H 4 + R ' H , (5a) and thus account f o r the h i g h e r va lue of k ^ / k g . To est imate the. importance of such r e a c t i o n s , the va lue of k j A 2 was measured f o r each experiment o f t h i s s tudy by a n a l y s i s on the gas chromatograph. I t i s e a s i l y shown t h a t k,. £ = « »r-,1. ...,; 1 ,;, , ,• • M R * 0 4 H 1 0 where CD} r epresent s the c o n c e n t r a t i o n of d i e t h y l ketone I n molecule cm*"^. The r e s u l t s o f James and S t e a c i e (17) on the p h o t o l y s i s o f pure d i e t h y l ketone gave the v a l u e of fc4/lc2* = 1 0 ( " ? ' 5 * ° * 1 ' e x P (-7800 .± 200) /RT I n good agreement w i t h r e s u l t s o f the o t h e r workers (23) (29) . I f a gaseous mixture of an o l e f i n i c compound and d i e t h y l ketone I s i l l u m i n a t e d , the m e t a t h e t i c a l and a d d i t i o n r e a c t i o n s o f e t h y l r a d i c a l w i t h the o l e f l n l c compound w i l l take p l a c e . A t h i g h e r i n t e n s i t i e s the m e t a t h e t i c a l r e a c t i o n w i l l take the course % / R ' R R { CpHr-. + p - 0 S 0 2H 6 + \ = c ' (6) 3 H H H H £ OpHr-R R' ° 2 H 5 * + / ° = 0 / 0 : = c \ ^ ( 6 a ) H X H H H The r a t e constant o f the r e a c t i o n (6) i s g i v e n by the f o l l o w i n g e q u a t i o n , which remains v a l i d even I f (6a) does not repre sent the e x c l u s i v e . f a t e o f the, o l e f l n l c r a d i c a l ; R - R C 2 M a Coy * 4 V * 2 - • ^  ^ ' m ^ where (jB J^ r epre sent s the c o n c e n t r a t i o n qf an o l e f i n i c -3 compound i n molecule cm • The a d d i t i o n o f the e t h y l r a d i c a l to an o l e f i n i c compound w i l l take the course -.10 -0 2 H 5 + R " .CH = OH.RV R".OH. - CH.R* (7) " "! 0 H 2 C H 3 C 2 H 5 + R».OH - OHoR' — > R " .CH - CH.R' (7a) OHgCHj C H 2 C H 3 G H 2 0 H a I n a l l such cases e t h y l r a d i c a l s d i sappear from the system wi thout the f o r m a t i o n of 0 2 Hg or Oj^S.1Qi and.so the v a l u e of M f a l l s below u n i t y . S ince two e t h y l r a d i c a l s are e q u i v a l e n t to one o l e f i n ! c molecule i n the a d d i t i o n r e a c t i o n , the r a t e equat ion i s g i v e n by RG0 - ( R C2.H 6 + RC4H»o )• O o p o l y m e r l z a t l o h The phenomenon o f c o p o l y m e r i z a t l o n . i n which two or more d i f f e r e n t k i n d s o f monomer molecule en te r the same polymer c h a i n , has been known e m p i r i c a l l y f o r about h a l f a c e n t u r y . However, the t h e o r e t i c a l i n t e r p r e t a t i o n of the ex-p e r i m e n t a l data began main ly w i t h the work o f Mayo, W a l l i n g and t h e i r co-workers f r o m 1 9 4 4 onwards. D e t a i l e d e x p e r i -mental work on r a t e s o f c o p o l y m e r i z a t l o n was f i r s t p u b l i s h e d i n 1949 by W a l l i n g , : a n d by M e l v i l l e and h i s co-workers ; the l a t t e r , i n p a r t i c u l a r , have subsequently e l abora ted the a n a l y s i s o f c o p o l y m e r i z a t i o n k i n e t i c s . The c o n t r i b u t i o n o f c o p o l y m e r i z a t i o n s t u d i e s to the -11 -f i e l d of v i n y l polymerization l i e s not In the e luc ida t ion of the k i n e t i c s hut i n a considerable extension of our under-standing of the effect of s tructure upon r e a c t i v i t y , Consider a reac t ion mixture containing two monomers and Mg. Growing polymer r ad i ca l s In th i s system w i l l have e i ther ac t ive terminal M^ or ac t ive terminal Mg groups, and we s h a l l denote these r ad ica l s by M °^ and Mg* re spec t ive ly . The propagation react ions occurring In th i s system may there-fore be wr i t t en as follows s 11 k 1 2 M ^ + Mg Mg° Mg. + M r M ^ k 2 1 Mg- + Mg Mg- legg I t i s usual ly assumed that t h e . r e a c t i v i t y of the r a d i c a l i s independent of chain length and that the r e a c t i v i t y i s only determined by the terminal monomer u n i t . I f the molecular chain length Is great we may assume tha t , to a good approxi-mation, the monomer i s consumed only i n the propagation r e -ct ions so that we haves Mx r i Mi + % n =. X -when n i s the r a t i o of the numbers of moles of the two monomers - 12 -entering the polymer at any ins tan t , and ;r^ and r 2 are the r e a c t i v i t y r a t i o defined as; 'KJ r l = ^11/^12 r 2 = l E 22 / / ] E 21 When a 1 ,2 -d l subs t l tu ted ethylene i s one component of the monomer mixture, the value of r g has been found to he zero i n many cases -within a l i m i t of e r ro r . I f does not polymerize by i t s e l f , ( k 2 2 = 0 ) then the above equation i s r e -duced to n - 1 . = r x M x / Mg , or M x l og (1-n) = log + log This equation can be appl ied d i r e c t l y to the composition of the polymer formed i n the i n i t i a l , stages of copolymeriza-t i o n , provided that the amount of copolymer formed i s too small to cause a s i g n i f i c a n t change i n the molar f r ac t i on of e i ther monomer, c i s - trans Isomerlzation Geometrical i somerizat ion of c i s - and t rans- o le f ins has been studied by many workers. For the . reac t ion in;most cases, - 13 -Including thermal and catalyzed isomerlzat lons , i t has been found that the thermodynamically:.less: stable.Isomer (usually c i s ) reacts to form the more stable Isomer ( t rans) , i . e . k. > k t c However, there have been found a few exceptions. Olson and Hudson (26) have invest igated the isomerizat lon of a ser ies of o l e f i n i c acids i r r a d i a t e d by u l t r a v i o l e t l i g h t i n so lu t ion at 18°0. They found that the thermally more stable isomer, produced the less stable Isomer more r a p i d l y than the less stable isomer gave the more stable isomer, e .g . the quantum y i e ld s for reac t ions , (malelc ac id fumaric acid) and (fumaric ac id —^ malelc a c i d ) , are 0 .05 and 0 . 1 , r e s -r e c t l v e l y , fumaric ac id being the more stable Isomer. Among w e l l known isomeric o l e f i n s , o n l y d i c h l o r o ethylene (27) and d i f luoro ethylene (28) have been known to be excep-t ions i n that the c i s isomer i s thermodynamically more stable than the t rans . The scope of t h i s i nves t iga t ion The addi t ion of the e thy l r a d i c a l to the conjugated double bond has been studied i n our labora tory . In t h i s work> a c r y l o -n i t r i l e . and i t s mono-methyl der iva t ives ; me thac ry lon i t r i l e , c i s - c r o t o n o n i t r i l e and t r ans -c ro tonon i t r i l e were chosen as sub-s t ra tes . The pa r t i cu l a r in te res t of t h i s study i s that the effect of the substituen|%methyl group upon the r e a c t i v i t y of - 14 -the double bond can be a c c u r a t e l y determined f o r each o f the three p o s s i b l e methyl i somers . And a l s o s imple c o r r e l a t i o n s between the a d d i t i o n o f the e t h y l r a d i c a l and o ther r e a c t i o n s i f any. The p o l y m e r l z a t i p r i arid c o p p l y m e r i z a t i o n pf the c r o t o n o -n i t r i l e isomers were s t u d i e d . I t i s known t h a t 1 , 2 - d i s u b s t i t u t -ed ethylenes g e n e r a l l y po lymer ize o n l y w i t h great d i f f i c u l t y due to s t e r i c h indrance of the, a d d i t i o n a t the double bond. A c c o r d i n g l y c r o t o n o n i t r i l e , an isomer pf m e t h a c r y l o n i t r i l e Which e a s i l y p o l y m e r i z e s , was chosen as a monomer i n which both the p o l a r and s t e r i c ef fects . ; would be w e l l developed. The r e l a t i v e thermal s t a b i l i t y o f c i s - and t r a n s - c r o t o n i -t r i l e i s not known, a n d . t h e r e f o r e a few experiments on the thermal i s o m e r i z a t i o n o f the pure Isomers were c a r r i e d ou t . The Pourse o f r a d i c a l - i h d u c e d i s p m e r i z a t i o n o f c i s - and t r a n s -c r o t o r i p n i t r i l e was a l s o determined a t 8 5 ° 0 i n the l i q u i d phase, and some measurements made upon the corresponding r e -a c t i o n i s the gas phase which accompanies the normal a d d i t i o n r e a c t i o n of the e t h y l r a d i c a l s . M a t e r i a l s , EXPERIMENTAL D i e t h y l ketone and a c r y l o n i t r l l e , whi te l a b e l of Eastman Organic C h e m i c a l s r e a g e n t grade m e t h a c r y l o h i t r l l e s u p p l i e d by K & K L a b o r a t o r i e s , I n c . a Q d s tyrene and o ther v i n y l monomers;were p u r i f i e d on a,Beckman Megachrom p r e p a r a t i v e gas chroniatograph. Ooiiimereial mixture : o f b i s and t r a n s • c r o t o n o h i t r i l e , s u p p l i e d by P e n i n s u l a r Chemreseareh, I n c . was separated on the same appara tus , and 100$ pure c i s and t r a n s isomeirSv^were o b t a i n e d . * "Ucon P o l a r " : w a s the column used i n the Beckman Megachrom p r e p a r a t i v e gas chromatograph.. Hel ium was used as a c a r r i e r gas a t 10 p . s . i . and column temperature was from 110°C to 120°C f o r a l l compounds. Spectro grade a c e t o n i t r i l e s u p p l i e d by Eastman Organic Chemicals was ana lysed on P e r k i n Elmer gas chromatograph and was found to be 99 •9^ pure» and t h e r e f o r e i t was used wi thout any p u r i f i c a t i o n . Commercial grade benzoyl perox ide was d i s s o l v e d i n ch loro form and r e p r e c i p i t a t e d w i t h methyl a l c o h o l . T h i s r e c r y s t a l l i z a t i o n process was repeated three t i m e s . *HMR and U . V . a b s o r p t i o n s p e c t r a were t a k e n . f o r c i s -and t r a n s - c r o t o n o n i t r i l e . NMR; s p e c t r a were i d e n t i c a l w i t h those determined by G o l d s t e i n , Reddy, and Mande l l (30). U . V . a b s o r p t i o n of c i s - and t r a h s - c r o t d n o n l t r l i e s t a r t e d a t 2400 l a n d 2650 1 r e s p e c t i v e l y . - 16 -M e t h a n o l , e t h a n o l , ch loro form and carbon t e t r a c h l o r i d e , used f o r p u r i f i c a t i o n s o f copolymer and benzoyl p e r o x i d e , and as s o l v e n t s o f s p e c t r o s c o p i c a n a l y s i s were reagent grade. Apparatus and a n a l y s i s f o r gas phase r e a c t i o n s . Convent iona l high-vacuum technique as d e s c r i b e d by James and S t e a c i e (17) was employed. Mercury c u t - o f f s were used I n p l ace of s topcocks i n the p a r t o f the system ass igned to s t o r a g e , p r e p a r a t i o n , i l l u m i n a t i o n and a n a l y s i s . Th i s p r e c a u t i o n was taken to avo id e r r o r s a r i s i n g from the a d s o r p t i o n of r e -a c t a n t s , products or oxygen i n s topcock grease . The pressures of r e a c t a n t s were measured to 0.001 cm by the cathetometer . -( I ) O p t i c a l system. The fused quar tz r e a c t i o n c e l l was a c y l i n d e r 10,cm l o n g , 4 .5 cm i n d iameter , having an i l l u m i n a t i o n volume of 159 car.. I t was housed i n an a luminim b l o c k furnace whose temperature was measured by copper-constantan thermocouple and thermometer, and c o n t r o l l e d to ± 1 ° 0 . The B r i t i s h Thompson-Houston ME/D 250 W d . c . medium pressure mercury a r c p rov ided an i n t e n c e source of i l l u m i n a t i o n from a v e r y s m a l l a r e a , and a s i n g l e quar t z l e n s gave a p a r a l l e l beam which Just f i l l e d the c y l i n d r i c a l volume of the c e l l . No r a d i a t i o n can be detec ted from t h i s source w i t h i n the r e g i o n ,2482 to 2752 A owing to the r e v e r s a l o f the 2537 A l i n e . The -. 17 -p o s s i b i l i t y of mercury phonose^slt^a^i..pn..p^. accordingly be discounted. The e f f e c t i v e r a d i a t i o n was limited, to.a lower i n t e n s i t y than -3100 £ b y ; a Coming f i l t e r . Intensity was varied by a number of 3 mm sheets of pyrex glasses. An i n f r a red f i l t e r containing d i s t i l l e d water was also, used. •(1.1)7 Analysis Tha a n a l y t i c a l system included an i n i t i a l dry-ice trap to r e t a i n the bulklof^ithe'-re.actan.tS'.- a s o l i d nJLtrogen trap .to r e t a i n ethylene andethane„ a modified Ward s t i l l 9 a d i f f u s i o n pump and a combined Toepler pump and gas burette. Samples of. the gas fractions could be withdrawn a f t e r measiire-ment fo r analysis by the gas chromatograph. Carbon monoxide was removed from the higher-boiling.constituents at ^215°p, the G 2 hydrocarbons at -170°C, and the G^ hydrocarbons at «120 0G. The three fractions were analyzed, by the Perkin;! Elmer gas chromatograph. A two!metre column (J.) containing SiOg was used f o r the analysis of carbon monoxide and the G 2 hydroearbons. The gaschrpmatographle analysis was carried out at 80°G and with;helium; gas as a c a r r i e r at pressure 10 p . s . i . The carbon monoxide was found to be e s s e n t i a l l y pure and free from hydrogen and methane. The 0 g f r a c t i o n contained, ethane and ethylene, whose r a t i o was obtained by calcula t i n g the, peak areas. The r a t i p • was cprree^ed with a factor found by Brown (31) .,• who calibrated the actual r a t i o of ethane and - 18 -ethylene i n measurements on ghe gas chromatpgraph. The amount of the 0^ f r a c t i o n was also corrected f o r non Ideal behaviour. P J c W = P o b s c i . +: 3.25 X : P r t s c t . X 10 The 0^ f r a c t i o n was found to be pure butane by the Perkin Elmer gas chromatograph using a column (R) containing a polygl y c o l . 0 opolymerizat ion The weighed mixture of two monomers and benzoyl peroxide were placed i n a Pyrex tube approximately 8 cm. long and 1.2 cm. .diameter, degassed completely by 5 times of freezing, evacuation and melting under vacuum to remove a i r , and sealed. The pplymerizatlbn was carried out In water thermostat at 60.0°0. The degree of conversion to polymer did not exceed h% of either mpnpmer In :any case, and i n the case of styrene copolymerizatlon the v i s c o s i t y e f f e c t was n e g l i g i b l e , XLO'C polymer being pr e c i p i t a t e d . The polymers were precipitated with methanol. To p u r i f y the styrene-crotpnohitriie co-polymer s r e p r e c i p i t a t i o n was carried out with carbon t e t r a -chloride (solvent) and methanol ( p r e c i p i t a n t ) . Nitrogen analysis has been found to be the most e f f e c t i v e method to determine the composition pf copolymers containing nitrogen, therefore the OolemanModel 29^^Hltrogen Analyzer, a modified micro-Dumas method, was used. N.M.R.. spectra were, taken f o r - 19 -a n a l y s i s o f p o l y m e r s t o d e t e c t t h e m e t h y l g r o u p o f c r o t o n o -n i t r i l e u n i t s , h u t i t w a s I m p o s s i b l e t o d i s t i n g u i s h t h e m e t h y l g r o u p a n d t h e m e t h y l e n e g r o u p a s b o t h : p e a k s o v e r l a p p e d t o g i v e a s i n g l e b r o a d p e a k . I n f r a - r e d s p e c t r a w e r e t a k e n i n c a r b o n . t e t r a c h l o r i d e a n d c h l o r o f o r m s o l u t i o n , b u t f a i l e d t o g i v e q u a n t i t a t i v e a n a l y s i s o f c o p o l y m e r c o m p o s i t i o n b e c a u s e t h e p r o p o r t i o n o f c r P t P h o n i t r l l e u n i t s w a s s o s m a l l i n c p m -p a r i s d n w i t h t h e o t h e r m o n o m e r u n i t s . c i s - t r a n s I s o m e r i z a t i o n T h e r e t a i n e d b u l k o f t h e r e a c t a n t s w a s c o l l e c t e d a f t e r t h e p h o t o l y s i s o f d i e t h y l k e t o n e i n t h e p r e s e n c e o f c i s -a n d t r a n s - c r o t o n p n i t r l l e , a n d a n a l y z e d c n t h e P e r k i n E l m e r g a s c h r o m a t o g r a p h u s i n g t h e 2 m e t e r c o l u m n ( A ) . I n t h e l i q u i d p h a s e , a w e i g h e d m i x t u r e o f d i e t h y l k e t o n e a n d c i s - a n d t r a n s - c r o t o n o n i t r i l e w a s i r r a d i a t e d i n a q u a r t z t u b e 5 c m . l o n g a n d 1.2 c m . d i a m e t e r a t 85°o. A n a l y s e s f o r t h e i s o m e r i z a t l o n w e r e a l s o m a d e o h t h e s a m e c h r o m a t o g r a p h u s i n g t h e . 4 m e t e r c o l u m n ( R ) . T h e t h e r m a l I s o m e r i z a t l o n o f c i s - a n d t r a n s - c r o t o n i t r i l e w a s a l s o c a r r i e d o u t I n t h e l i q u i d p h a s e a t 260°0 a n d 190°c. S a m p l e s w e r e s e a l e d i n P y r e x t u b e s a f t e r d e g a s s e d . . A n a l y s i s w a s a l s o m a d e i n t h e s a m e w a y . RESULTS The values of (B) quoted i n the fo l lowing tables are i n i t i a l va lues . Where s i g n i f i c a n t , a cor rec t ion was applied for the change i n these quant i t ies due to the consumption of substrate, e.g..C r^<l^l»Qryl;onitril©; and a c r y l o n l t r i l e . Table 1. React ions of the e t h y l r a d i c a l w i t h a c e t o n i t r i l e . -II -3-1 ~<L 3/i_ -V^_ I mol. cm) 17 10 x Rx Imol,cm s ) (mol. cm, s. ) T°K . Time (sec) 10"TD3 10 CtO R C O K c a H 6 ' ^ H H - R C * H , 0 m k s A 2 I ^ A a idWk* 360 3600 7.70 4.78 26, 97 3.84 2,83 19.58 .868 .144 .029 16.75 361 3600 7.72 9.61 33.04 5,28 2.94 25.92 .944 .113 -.193 2.34 363 43200 3.52 15.37 .986 .354" ,092' .596 , 963: .154" -.007" , 30; 381 27900 3.38 11.94 .746 ,272 .072 .462 .984 .155 .074 .15 382 3600 6.37 4.23 20,63 3,84 1.88 14,503 ,889 .129 .228 14.20 388 3600 6.41 9.88 23.73 4.69 1,97 18.23 ,965 .108 1.431 1.93 400 3600 7.22 3.59 25.54 7.62 3,45 18.81 1 .034 .183 -.032 -§.66 415 2900 2.35 13.79 4.63 1,48 .32 3.08 .986 .103 .003 .26 480 14400 4.98 2.65 7.12 3,57 .39 3.19 .949 .122 .048 7,61 Table 2. Reactions of the e t h y l r a d i c a l w i t h c i s - c r o t o n o n i t r i l e (mol.cm ) 10 (mol. cm s. ) (cm mol. s. ) f s , . A__ 1- S T°K Time (sec) ld , 7CD3 lO^B) R c o R C LH F A R c * r W .HC*H.. m k 3 / k 2 10 u k. 7 Aa 327 . 7200 7.087 2.477 7.66 1.11 .66 .5.41 .851 .122 19.8 328 3600 . 9.430 3.682 25710 3.11 2.24 18.79 . 86 9 .120 20.1 334 3600 7.237 2.548 7.64 1.19 .66 5.16 .830 .128 22.5 343 3600 6.939 2,336 8.46 1.3.5 .65 5 c 56 .816 .117 28.2 345 3600 8.433 3.299 36.64 4.46 £ 3 . 3 3 26 c 00 .831 .124 26.9 358 3600 7.134 1.838 9.64 2.24 .90 5.87 .841 .153 34.3 362 3600 7.871 2.855 35.84 5.17 2.85 23.54 .801 .121 51.5 368 3600 7 .794 3.208 35.18 -4.92 2.87 22.09 .768 .130 54.2 373 3600 6.400 1.462 9.69 2.06 .75 6.01 .833 .124 45.2 374 3600 8.477 2.741 38.44 5.91 3.06 2.4.38 .788 .126 60.2 383 3600 7.553 2.497 36.90 6.12 2.69 21.70 .754 .124 78.1 383 3600 6.144 1.357 9.42 2.34 .69 5.29 .811 .130 57.1 384 3600 6.714 1.384 10.42 2.67 .71 5.71 .804 .123 61.7 387 3600 5.359 2.131 7.93 1.91 .44 3.53 .687 .123 61„0 387 3600 5.579 1.368 8.66 2.2.4 .58 4.37 .763 .132 71.9 387 3600 6 .266 1.037 9.86 2.74 o63 5.21 .806 .120 80.8 T a b l e 2. R e a c t i o n s o f the e t h y l r a d i c a l w i t h c i s - c r o t o n o n i t r i l e ( c o n t i n u e d ) (mol. -3. cm ) 10 (mol.cm s. ) (cmmol. T* K Time (sec) 10~'7JD} To^B) Rco RciHb , RGHI*. RG4HID M 387.5 3600 5-. 81-4 1.978 8.98 2.32 .53 3.91 .694 .136 70.1 388 3600 5.584 3.333 8.33 1.78 .33 2.45 .508 .135 78.5 389 3600 7.408 2.181 38.12 6.88 3.01 23.42 .791 .129 74.1 393 3600 5.459 1.033 8.71 2.60 .63 4.81 .850 .130 57.5 395 3600 6.038 .934 9.75 2.85 .77 5.47 .852 .140 65.9 400 3600 6.382 1.288 24.55 6.11 1.68 13.96 .817 .121 93.1 411 3000 5.909 .734 9.30 3.00 . 60 4.68 .825 .128 102 415 3600 7.361 3.011 29.74 7.26 1.47 12.17 .653 .120 98.1 431 3600 7.025 1.572 30.57 10.20 1.98 13.62 .779 .146 116 432 3600 6.960 2.458 30.38 9.21 1.51 11.93 .696 .127 109 453 3600 6.765 2.307 25.23 9.88 1.32 8.58 .732 .153 1000 470 3000 7.369 2.382 15.28 7.94 .89 4.55 .818 .195 54.8 So ) Table 3. Reactions of the e thyl r a d i c a l with t r ans -c ro tonon i t r i l e (mol. cm ) 10" (mol.cm s. ) (cm mol. T°K Time(sec) io"l7rD] I 6 , 7 C B ) Hco Rc^Hio M k 3 / k . 10 B k 7 / l 324 5400 7.284 2.619 16.40 2.06 1.53 12.39 .881 .123 21,1 332 5400 6.850 2.711 6.26 .98 .48 3.70 .748 ,129 30.3 333 3600 8.218 2.123 24.66 3.18 2.22 18.81 .892 .118 22.4 339 3600 8.066 3.179 22.89 3.00 2.04 16.25 .841 ,125 28.5 341 3600 5.806 1.632 7.10 1.15 .64 4.48 .793 . 143 42,5 342 3600 7.553 2.918 17.38 2.28 1.36 11.55 .795 ,117 27.1 351.5 3600 6.698 1.520 8.57 1.48 .74 5.32 .792 .138 50.8 353 3600 8.039 2.578 17.53 2.67 1.30 11.03 .782 .117 44.7 359 3600 8.324 2.345 29.86 4.35 2.49 20.90 .846 .119 43.0 360.5 3600 6.556 1.521 9.17 1.67 .74 5.29 .760 .139 62.9 361 3600 7.457 1.512 7.16 1.67 .51 3.53 .727 .143 68.9 368.5 3600 6,164 1.56.0 8.51 1.66 .61 4.88 .769 .125 57.1 369 3600 7.775 2.426 23,05 3.50 1.73 13.74 .748 .126 64.5 374 3600 6.945 2.688 25.89 3.83 1.63 14,52 .708 .112 73,7 377 3600 5o915 1.543 7.00 1.66 .39 2.94 ,657 .132 90,8 Table 5c Reactions of the e thyl r a d i c a l wi th t r ans -c ro tonon l t r i l e (continued} (mol.cm 5) 10~ l i(mol. cm3s".1 ) ~7~N , ^ _ j Rc 2 Ht R&.H*. R&tH.o M ^3 / k z (cm mol. s. ) T°K Time (sec) l C ' C D ) ,10'7[B) RCO i<y*k7/kj 379 .3600 6.640 2.607 6.25 1.30 .23 2.08 .540 .111 76.5 379 3600 7.401 1.519 7.80 1.95 .31 3.66 .720 .085 75.1 380 3600 7.585 2.541 27.93 4.95 2.02 14.43 .694 .140 88.5 386 3600 7.546 3.031 29.03 4.68 2.10 15.77 .705 .133 71.2 386.5 3600 5.860 1.375 8.60 2.08 .56 4.11 .719 .137 86.5 391 3600 5.685 1.399 8.49 2.14 .42 3.49 .663 .119 110 395 3600 7.285 1.557 6.502 2.04 .40 2.25 .659 .177 94.9 402 3600 7.117 2.559 28.08 5.45 1.84 13.38 .670 .138 98.9 407 3000 5.457 1.193 8.21 2.42 .47 3.06 .667 .153 131 411 3600 6.656 2.080 23.46 5.25 1.59 10.99 .692 .145 105 421 3000 5.187 1.121 7.57 2.77 .38 2.32 .672 .164 145 425 3600 5.883 1.315 24.33 5.40 2.57 11.11 .679 .231 178 436 3600 .6.116 1.730 22.58 6.59 1.31- 9.17 .698 .142 130 438 3000 5.365 2.001 8.21 2.74 .21 1.13 .471 .189 204 (mol. cm ) 10" (mol. -3 -I cm s. ) (cm. m< T°K Time(sec.) Rco X .H* Rc»H/o M 10l3k~ 315 3600 8.907 0.433 17.89 2.30 1.79 11.05 .747 .162 315 321 1800 9.698 0.335 28.05 3.98 2.52 18.83 .813 .134 360 330 3600 8.589 0.294 29.37 3.79 2.79 18.74 .767 .149 537 332 1800 9.475 0.251 32.56 4.76 2.76 22.29 .831 .124 465 332 1800 8.031 0.347 26.18 3.66 2.20 16.01 .751 .137 469 332 1800 9.225 0.198 27.42 3.84 2.44 18.49 .814 .132 598 338 3600 8.149 0.398 31.56 4.53 2.23 17.68 .704 .126 559 341 3600 8.332 0.184 34.65 4.71 3.15 22.60 .788 .139 839 342 1800 9.052 0.225 35.78 5.12 2.79 21.98 .757 .127 823 355 2700 8.418 0.339 43.58 6.18 3.35 25.31 .723 .132 709 356 1800 7.557 0.277 28.84 4.16 1.96 13.39 .609 .146 1084 358 3600 6.905 0.215 31.30 4.90 2.35 17.74 .723 .133 955 363 2700 8.897 0.248 20.40 3.54 1.54 10.57 .692 .146 781 0 So ,•2. Table 4. Reactions of the ethyl r a d i c a l with methacrylonitrile (continued) (mol.cm"3j 10""'a'(mol.cm3 s j 1 ) (cm^mol!" ) T°K Time (sec.) RI<f',(1D) 1 0 ^ ^~^^Z^T^H^ R&.HI 0 M k s A a 1 0 % A* 368 3000 8.619 0.236 34.49 5.62 2.77 18.89 .710 .147 973 373 3600 7.722 0.193 21.98 4.17 1.61 11.60 .717 .139 946 375 2700 7.445 0.200 32.40 5.77 2.27 15.69 .662 .145 1381 401 1800 7.714 0.110 30.72 7,87 2.15 15.41 .758 .139 1721 405 1800 7.217 0.155 24.69 5.71 1.44 10.57 .660 .136 1667 405 1800 7.618 0.157 31.68 7.18 2.08 13.90 .665 .149 1813 405 1800 7.425 0.115 28.45 7.53 1.78 12.86 .717 .138 1955 Table 5. Reactions of tha ethyl r a d i c a l with, a c r y l o n i t r i l e (mol . cm3). 1C -10. ) (mol, A. -3 , cm. sV ) (cm.mol. T°K Time lsec) 10",7CDJ io~ , 7 CB\ Rco R o i H f , \ Rc*Hio M 310 3600 8.36 .330 21.04 2.60 1.88 15.043 .839 .125 265 318 3600 "8.83 .272 28.86 3.22 2.45 19.96 .803 . 123 467 318 1800 8.76 .343 26.09 3.13 2.32 17.51 .791 .133 380 324 2700 8.19 .209 13.67 1.39 1.00 7.92 .681 .126 740 328 1800 8.74 .249 31.90 3.66 2.43 20.11 .745 .121 728 333 3000 8.70 .164 30.65 3.23 2.71 19.87 .756 .136 1034 335 3600 8.63 .155 31.74 3.64 2.59 21.82 .802 .119 868 343 3000 8.42 .179 29.43 3.19 2.31 18.31 .730 • 12© 103!? 348 2400 8.05 .179 30.963; 3.63 2.53 19.14 .736 .132 1044 354 1800 7.96 .135 31.26 4.11 2.37 16.74 .667 .141 1805 357 1800 8.23 .104 32.76 4.52 2.37 19.67 .738 .120 1865 358 3600 7,65 .170 30.00 3.91 2.07 17.58 .716 .118 1193 360 1800 8.12 .147 24.71 3.28 1.72 13.95 .697 .123 1411 377 1800 7.15 .148 28.22 4.87 1.92 16.10 .743 .119 1222 387 1200 7.92 .142 24.96 4.56 1.63 12.60 .687 .129 1547 405 1800 6.83 .197 33.10 7.57 2.04 16.17 .717 .126 1847 2.5 1,0 i i i I 1 I I I I I 1 1 ' I 2.0 "2-5 3 .0 l o 3 / T -K Fig.1 The addition reaction of the ethyl r a d i c a l with c i s - and trans- crotononitrile,, s o l i d c i r c l e s : - c i s - c r o t o n o n i t r i l e open c i r c l e s : - trans-crotononitrile g n * I • . . I . . . . I . . I 2 . 0 2.5 30 /T °K Pig 02 The addition reactions of the ethyl r a d i c a l "with methacrylonitrile and a c r y l o n i t r i l e . O methacrylonitrile, © a c r y l o n i t r i l e ( t h i s work) O a c r y l o n i t r i l e ( James and MacOallum ) Table 6. Copolymerization of crotononitrile with styrene. (Benzoyl peroxide]) = 1 x 10~ mole/lit. 2 mole x 10 Ml M2 VM2 Conversion* % N content % n (i) cis and trans mixture (70:30), at 65°C. 1.74 0.62 2 . 8 1 38.2 0.38 35 1.74 1.23 1.41 33.4 0.57 23 1.74 1.85 0.94 22.5 0 . 7 8 •16 .6 1.74 2.46 0 . 7 1 20.8 0.98 13 1.74 4.93 0.35 3 . 5 1 1.50 • 8.3 1.31 5.48 0.24 1.39 2.05 5 .9 0 . 8 7 6.16 0.14 1.39 2 . 7 2 4.3 0.44 6 . 7 8 0.065 0 . 7 8 4.05 . 2.7 ( i i ) cis-crotononitrile, at 60°C. 2 . 1 7 8 3 . 0 8 2 0 . 7 0 5 2.7 0.88 14.65 1 . 7 4 2 3.698 0 . 4 7 1 2.4 1.26 10.04 1.307 4.315 0.303 1.9 1.74 7 . 0 9 0 . 8 7 1 4.931 0 . 1 7 7 1.5 2.36 5.06 ( i l l ) trans-crotononitrile, at 60CC. 2 . 1 7 8 3 . 0 8 2 0.705 3.4 0 . 8 2 15.77 1.742 3.698 0 . 4 7 1 2.7 1.11 11.48 1.307 4.315 0.303 1 .9 1.58 7.86 0 . 8 7 1 4.931 0 . 1 7 7 1.3 2.15 5.62 0.433 5.548 0 . 0 7 8 0.8 2 . 9 4 3 . 9 3 ; styrene, ; crotononitrile, and n ; number of moles of styrene in copolymer, to 1 mole of crotononitrile. *• for total weight of two monomers. Pig.3a. Oopolymerization of c r o t o n o n i t r i l e with styrene at 65 0 . Crotononitrile i s the mixture of c i s and trans, 70 and 30$ respectively. Pig. 3b. Copolymerization of c i s - and t r a n s - c r o t o n o h i t r i l e , each at 60 0. © ; c i s , O J trans. Table 7 The photosensitized isomerization of c i s - and trans-crotononitrile. i n the liquid phase i n the presence of diethyl ketone. (i) cis — ^ trans ( i i ) trans—» cis time(hr) % trans time(hr) % cis 2 0.3 4 2.1 3 1.4 5 3.2 4 2.1 10 4.5 10 5.6 11 4.5 15 7.0 12 4.6 ,,26 '10.7 26 6,8 Temp....,85°G (^diethyl ketoneJ= 0.01 mole. £crotononitrile}= 0. The thermal isomerization. ( liquid phase ) (i) Temp....190°C. Time.....4 days. 100 % cis — » 98.2 % cis 100 % trans > 96 % trans ( i i ) Temp...260°C Time.....3 days. 100 % cis — > 65.3 % cis 100 % trans —±? 41 $ trans Ul o w 10 0 F i g . 4-o cis-trans Isomerization of c r o t o n o n i t r i l e i n the l i q u i d phase i n the presence of diethyl ketone. ^ ; initially !oo% cis / \ J » » trans A A A A A i o 20 T I M E (hr) 30 - 36 -O o p o l y m e r i z a t i o n An attempt to po lymer ize pure o r o t o n i t r i l e was made u s i n g 2 x 10 mole per l i t e r benzoyl peroxide as a c a t a -l y s t , but no polymer was obta ined a t 6 5 ° 0 a f t e r 10 hour s . The p o s s i b i l i t y o f c o p o l y m e r l z a t l o n of c r o t o n o n i t r i l e w i t h v a r i o u s v i n y l monomers was i n v e s t i g a t e d . I t was found t h a t s t y r e n e , methyl m e t h a c r y l a t e , methyl a c r y l a t e and acrylo?> n l t r i l e would g ive copolymers w i t h e r o t o n o n l t r i l e . I n f r a r e d s p e c t r a and a n a l y s i s of the polymer f o r J content gave q u a n t i t a t i v e evidence t h a t the polymers obta ined conta ined some c r o t o n o n i t r i l e u n i t s . A c r y l i c a c i d pp lmer lzed r a p i d l y i n .'.the presence of c r o t o n o n i t r i l e but the polymer was pyre p o l y a c r y l i c a c i d . V i n y l a c e t a t e , though I t was expected t o y i e l d a copolymer, d i d not po lymer ize i n the presence of c r o t o n o n i t r i l e a t 65Q0 f o r 24 hour s . I n the above two cases the i n i t i a l molar f r a c t i o n o f c r o t o n o n i t r i l e was/?,50. A s e r i e s o f experiments o f e o p p l y m e r i z a t i o h of s tyrene w i t h c r o t o n o n i t r i l e was c a r r i e d out a t 65 °0 and 6 0 ° 0 . The r e s u l t s were summarized I n Table 6 and F igure s 3a and 3b. The va lues f o r r-^ f o r c i s - .and t r a n s - c r o t o n o n i t r i l e were obta ined by i n t e r p o l a t i o n from F i g u r e 3b u s i n g e q u a t i o n , n-1 = r 1 % / M 2 - 37 -c i s - t r a n s I somerizat ion" : I t was found t h a t the i s o m e r i z a t i o n r e a c t i o n was t a k i n g p l ace when an I n i t i a l l y pure sample of e i t h e r c i s - or t r a n s -c r p t o n o n l t r i l e was mixed w i t h d i e t h y l ketone, and i r r a d i a t e d by 3130 £ r a d i a t i o n i n . t h e . necessary presence o f the e t h y l r a d i c a l i n the gas phase. The more q u a n t i t a t i v e I n v e s t i g a t i o n s were made I n . t h e l i q u i d phase, and i t was found i n t h i s case t h a t c i s -c r o t o n o n i t r i l e y i e l d e d the t r a n s Isomer more r a p i d l y than the t r a n s gave the c i s i somer under e q u i v a l e n t , c o n d i t i o n s . Some experiments o f pure thermal i s o m e r i z a t i o n o f c i s - and t r a n s - c r p t o n o n i t r i i e i n the l i q u i d phase were a l s o c a r r i e d out I n sea led pyrex tubes at 260 °0 f o r 3 days and a t 19P°0 f o r 4 days . . The r e s u l t s were summarized i n Table 7 and F i g u r e 4. Dur ing the thermal i s o m e r i z a t i o n r e a c t i o n a t 260° ;C, c r o t o n o n i t r i l e y i e l d s s m a l l amounts o f a l l y l c y a n i d e , and t h i s molecular , rearrangement was found more iiapMr£i?dnv c i s -e r o t o r i o n i t r l l e than t r a n s - ; about 5 t imes more (3.6$ of a l l y l cyanide was produced from c i s - c r o t o n o n i t r i l e a t 26O°0 a f t e r 4 d a y s ) . The a n a l y s i s o f a l l y l cyanide was c a r r i e d out by gas chromatograph u s ing the column R; the peak of a l l y l cyanide appeared between the peaks o f c i s - and t r a n s - c r o t o n o h i t r l l e . 38 -DISCUSSION REACTION OF THE ETHYL RADICAL WITH ACETONITRILE In. the r e a c t i o n ,of the e t h y l r a d i c a l w i t h a c r y l o n l t r i i e and I t s m e t h y l , d e r i v a t i v e s „ I t has been found t h a t the r a t e constant f o r the a d d i t i o n o f the e t h y l r a d i c a l to the earbpn carbon double bond may be measured i n every case , b u t the a b s t r a c t i o n o f the hydrogen atom by the e t h y l r a d i c a l p r o -ceeds too s l o w l y £of accura te measurement. I t appeared to be d e s i r a b l e to de te ra lne f i r s t I f the e t h y l r a d i c a l would r e a c t w i t h a c e t o n ! t r l l e „ i n order to determine whether the r e a c t i o n s o f 'addit ion- o f the e t h y l r a d i c a l to the carbon: n i t r o g e n t r i p l e bond, and a b s t r a c t i o n o f a .hydrogen atom from a methyl group a d j a c e n t . t o the carbon carbon double bond by the e t h y l r a d i c a l , w o u l d proceed a t a s i g n i f i c a n t r a t e . A t v a r i o u s l i g h t I n t e n s i t i e s , cpncent ra t ions and temperatures , the r a t e constants f o r the a d d i t i o n p f the e t h y l r a d i c a l to the carbon n i t r o g e n t r i p l e bond o f a c e t o -n i t r i l e were found to be l e s s than 1% and 0 . 1 # p f these found f p r c r o t o n o n i t r i l e and a c r y l o n l t r i i . e r e s p e c t i v e l y . Moreover , over the r a n g e . o f temperature o f t h i s ; I n y e s t i g V -t i o n , the normal r e g u l a r i t y o f the i n c r e a s e o f the r a t e constants w i t h the i n c r e a s e o f the temperature was not apparent,. The r a t e penstants f p r the a b s t r a c t i o n r e a c t i o n c f the e t h y l r a d i c a l w i t h a c e t p n l t r l l e were a l s o fpund t o : - 39 -be very small (Table l ) and comparable wi th the values observed for n-heptane (17). In such cases where true abs t rac t ion and addi t ion rate constants could not be measur* ed accurately as these reactions proceed too s lowly , i t i s of Interest to estimate, for each experiment, the maximun probable value that the rate constant for these react ions could have while remaining at the l i m i t of the p rec i s ion of the measurements. Therefore, the upper l i m i t values of the rate constants of the react ions of the e t h y l ; r a d i c a l wi th ace ton i t r i l e . were calculated by the approximation as fo l lows; for tyk0* o . i Ja3 i L , for K 7 A P * 0.05 -S^S-The quant i t ies of these values are compared wi th the rate constants of the reac t ion of the e thy l r a d i c a l wi th a c r y l o -n i t r l l e (for K 7 A 2 ^ ) Table 8 and wi th heptane and heptene (for k 6 / l c 2 ^ ) Table 9.. The r e a c t i v i t i e s of the ON t r i p l e bonds of a c r y l o n i t r l l e , methacry lon i t r i l e and a c e t o n i t r i l e have been studied i n spec ia l cases. Studies on polymerizat ion of a c r y l o n i t r l l e (32)(33) have suggested that the p o l y a c r y l o n i t r i l e r a d i c a l adds to the ON t r i p l e bond, forming the ketene-imlne s tructure i n the polymer chain , but the proport ion of t h i s - 40 -r e a c t i o n t o the normal a d d i t i o n r e a c t i o n i s s m a l l . Beevers (34) has s t u d i e d the U . V . s p e c t r a of p o l y a c r y l o n i t r l l e and p p l y m e t h a c r y l o n i t r i l e prepared i n v a r i o u s exper imenta l con-d i t i o n s t o I d e n t i f y the ketene- imine s t r u c t u r e i n the polymer c h a i n , and has found t h a t the a b s o r p t i o n s p e c t r a shows an a b s o r p t i o n band which can be a s c r i b e d to the ke tene- imine s t ruc ture ; . I n our p o l y m e r i z a t i o n s tudy of c r o t o n o n i t r i l e , which w i l l be d i scus sed i n the l a t e r s e c t i o n , the polymers were examined by the I . E . t e c h n i q u e , but ho evidence o f an a b s o r p t i o n band corresponding to the -C=N- l i n k a g e was observed. The p o l y m e r i z a t i o n of a c e t o -n i t r i l e to a s t r u c t u r e c o n t a i n i n g r e p e a t i n g k e t l m l n e l i n k -ages has been r e p o r t e d , (35) but the r e a c t i o n mechanismtf OH t r i p l e bond p o l y m e r i z a t i o n i s o f i o n i c c h a r a c t e r and the c a t a l y s t is , o f the P r l e d e l - O r a f t c l a s s . Wi jnen (36) has r e p o r t e d the r a t e constants f o r the a b s t r a c t i o n o f hydrogen atom from a c e t o n i t r i l e by the OD^ r a d i c a l ' The r e l a t i v e r a t e constants f o r the a b s t r a c t i o n r e a c t i o n w e r e obta ined by f o r the r e a c t i o n s 3 + CH,QN 0D 3 H + 0H 2 0N 2CD Table 8. The addition of the ethyl r a d i c a l to a c e t o n i t r i l e Temp. (°K) M l o l 3 k 7 / k f 101 30.05 Rco (B) R a 1 0 1 3 k 7 / k | f o r a c r y l o n i t r i l e b a/b x i c r . 360 0.868 16.74 6.37 1297 4.91 361 0.944 2.34 3.37 1312 2.57 363 0.963 0.30 0.42 1352 0.31 381 0.984 0.15 0,46 1680 0.27 382 0.889 11.20 6.405 1690 3.79 388 0.965 1.93 2.81 1841 1.53 400 1.034 -5.66 8.21 2080 3.95 415 0.986 0.26 0.96 2420 0.39 480 0.949 7.61 7.51 4280 1.75 •Table.9. The abstraction of the hydrogen atom from a c e t o n i t r i l e templ ° K ) I O ' V ^ 10 < 2fij) ki a 34 ->/Z cm mol. sec. lO^ kfe/lg-for n-heptane b 10l3k6/kt for 1-heptene c lO^Wk^ by CD5 a/b a/c 360 0.029 0.478 3.55 1.38 0.13 361 -0.193 0.412 3.72 1.45 0.11 363 -0.007 0.218 3.81 1.55 0.06 381 0.074 0.246 1.05 6.60 2.95 0.23 0.04 382 0.228 1.220 1.09 . 6.92 3.10 1.12 0.17 388 1.431 0.646 1.35 8.52 3.76 0.48 0.07 400 -0.032 2.681 2.10 12.0 5.63 1.28 0.22 415 0.003 0.489 3.31 13.3 8.91 0.15 0.03 480 0.048 6.806 13.5 15.3 44.7 0.50 0.44 - 43 ;-Those., .values'.; f o r the r a t e constants of. h i s work are com-pared w i t h the upper l i m i t va lues for the a b s t r a c t i o n r e -a c t i o n of the e t h y l r a d i c a l w i t h a c e t o n i t r i l e o f t h i s work i n Table 9. T h e r e f o r e , i t was concluded t h a t the a d d i t i o n of the e t h y l r a d i c a l to the ON t r i p l e bond and the a b s t r a c t i o n Of hydrogen atom by the e t h y l r a d i c a l cou ld be neg lec ted i n the s tudy of the r e a c t i o n s o f the e t h y l r a d i c a l w i t h c i s -and t r a n s ^ ;e..ro^qnoni.trlle:V' m e t ^ c r y l o n i t r i l e and a c r y l o -n i t r i l e . REACTIONS OF THE ETHYL RADICAL WITH P I S - AND TRANS- GROT ONONITRILE Q u a n t i t a t i v e r e s u l t s on the r a t e s o f the r e a c t i o n s , o f the e t h y l r a d i c a l w i t h c i s - and t r a n s - c r o t o n o n i t r i l e are summarized i n Tables 2, andl 3, and F i g u r e 1. I n each case i t was e s t a b l i s h e d t h a t the a b s t r a c t i o n of a. hydrogen atom from the methyl group d i d not Occur s u f f i c i e n t l y . r a p i d l y for. measurement under the exper imenta l c o n d i t i o n s , v a l u e s o f FC6/kg^ be ing l y i n g w i t h i n a narrow range about z e r o . The v a l i d i t y o f the r a t e equat ioh was. t e s t e d by v a r y i n g the c o n c e n t r a t i o n s o f the r e a p t a n t s , and the i n t e n s i t y o f i l l u m i n a t i o n and t h e r e f o r e the c b h c e n t r a t i p n of the e t h y l . r a d i c a l . I t was found t h a t the v a l u e s o f the r a t e constant are independent o f the l i g h t I n t e n s i t y , suppor t ing the - 44 mechanism of the proposed r e a c t i o n . S t a t i s t i c a l a n a l y s i s o f the two se t s o f ^ r e s u l t s f o r a d d i t i o n o f the e t h y l r a d i c a l to c i s - and t r a n s - c r o t o n p -n i t r i l e shpw t h a t there, i s no s i g h l f i c a j i t d i f f e r e n c e s between the va lues e i t h e r o f the energy of a c t i v a t i o n or o f the p r e - e x p o n e n t l a l f a c t o r f o r the two i somers . A t the 5% p r o b a b i l i t y l e v e l i t was found t h a t E 7 " « E 2 13 + l o g 4|| c l s - c r o t p n o n i t r i i e 4.85 ± .68 4.56" ;* *40 t r a n s - " 4.69 ± . 9 6 4.57 *• .60 Even a t the 50% p r o b a b i l i t y l e v e l no s i g n i f i c a n t d i f f e r e n c e can be o b t a i n e d . I n . a d d i t i o n the probable e r r o r s i n the va lues o f the r a t e constant a t any g i v e n temperature do not r e v e a l any s l g n i f1 c a n t d i f f e r e n c e i n ; r e a c t i o n . The d i f f e r e n c e between r e a c t i v i t y o f c i s - and t ransr c r o t o n p n i t r i l e towards the e t h y l r a d i c a l , a l though i t i s s m a l l and not q u a n t i t a t i v e , can be seen i n F igure 1, showing t h a t the t r a n s isomer i s a p p a r e n t l y more r e a c t i v e . Thermal Is . omer iza t ipn of p i s - and t r a n s - c r o t o n o n i t r i l e shows t h a t the c i s i s thermodynamipal ly more s t a b l e than the t r a n s , t h e r e f o r e i t may be s imply oonsidered t h i s i s g e n e r a l t h a t the t h e r m a l l y l e s s s t a b l e isomer; shpuld be more r e a c t i v e * Hcwever, the methyl a f f i n i t i e s f o r a s e r i e s o f c i s - 45 -and t r ans I s o m e r s e > g . , 2 » b u t e n e s 9 d i - t - b u t y l e t h y l e n e s , s t i l b e n e s , and d i e t h y l maleate and d i e t h y l fumarate , have been s t u d i e d a t 6 5 ° 0 by Szwarc and b i s co-workers (12) . In- t h e i r .wo.tkV,t^eUreaetl7l;ty o f the methyl r a d i c a l t o -wards the Isomer i s expressed i n the form o f a r a t i o o f r a t e c o n s t a n t s , ^2 /k^ thus s k x •OHj + i s o - p c t a n e CH^ + I s o - o c t y l r a d i c a l k P • 0 H 3 + RCHsOHR' 0 H 4 + R O H O H ( G H 3 ) R ' T h e i r r e s u l t s showed t h a t w i t h s t l i b e n e s , and a l s o d i e t h y l maleate and fumaratey the t h e r m a l l y more s t a b l e isomer i s the more r e a c t i v e . However 9 Szwarc does not g ive the p r o -bable e r r o r o f h i s measurements and the apparent d i f f e r e n c e may not be s i g n i f i c a n t . T h e i r r e s u l t s are as f o l l o w s ; i somer l / k 2 c i s - b u t e n e - 2 3.4. t rans-betene-2 6.9 c i s - d i r t - b u t y l e t h y l e h e 1.9 t r a n s - d l - i t - b u t y i e t h y l e n e 0 . 4 c l s - s t i l b e n e 29 .0 t r a n s - s t i l b e n e . 104.5 d i e t h y l maleate 333. d i e t h y l fumarate 1998. K o c h i (37) has made an i n v e s t i g a t i o n on r e a c t i o n of. benzoyl perox ide and o l e f i n s c a t a l y z e d by cupper s a l t s , and i n a c e t o n i t r i l e and benzene s o l u t i o n s c l s -butene-2 was found t o be 1.8.^» 2 i l t imes more r e a c t i v e than the t r a n s I somer . Ayscpugh e t . a l . * (38) has s t u d i e d the p h o t o c h l o r l n a t l o n of c i s - and t r a n s - d i c h l o r 0 e thylene i n .-. 46 -the gas. phase and f o u n d . t h a t the c i s Isomer was added more r a p i d l y by the c h l o r i n e r a d i c a l than the t r a n s isomer,,: S tud ie s on the c o p o l y m e r i z a t l o n i n which one monomer I s a - 1,2 -d l subs t i tu ted e thylene , have bsen I n v e s t i g a t e d by Lewis and Mayo (39)(40), The r e s u l t s o f these works are summarized i n Table 10. Uo g e n e r a l c o n c l u s i o n appears p o s s i b l e on the ba s i s o f these r e a c t i v i t y d i f f e r e n c e s o f c i s and t r a n s i somers towards v a r i o u s r a d i c a l s , and no c o r r e l a t i o n o r . p a r a l l e l i s m can be e s t a b l i s h e d between the r a d i c a l r e a c t i v i t y and thermal s t a b i l i t y , s i z e of a t t a c k i n g r a d i c a l or s u b s t i -t u e n t , o r e l e c t r o n i c p r o p e r t y o f r a d i c a l or isomer a t p r e s e n t . I n t h i s connexion i t I s important to mention t h a t the order o f r e a c t i v i t y o f a e l s - t r a n s p a i r towards an a t t a c k i n g r a d i c a l i s s e n s i t i v e to s m a l l changes i n the nature of r a d i c a l ; i n t h i s I n v e s t i g a t i o n i t was found t h a t the order o f r e a c t i v i t y o f the p r o t o n o n i t r i l e s towards the e t h y l r a d i c a l was r ever sed when the p o l y s t y r y l r a d i c a l was the a t t a c k i n g s p e c i e s . The e t h y l and p o l y s t y r y l , r a d i c a l s are s i m i l a r i n t h e i r p o l a r c h a r a c t e r i s t i c s , but d iverge I n r e -spect o f the s t e r i c c o n d i t i o n o f the carbon atom w i t h the f r e e v a l e n c e . r I n the r e a c t i o n o f the e t h y l r a d i c a l w i t h c i s - and t r a n s - c c o t o h p n i t r i l e , I t was found t h a t the a d d i t i o n r e - , a c t i o n was accompanied by a much more r a p i d , r e a c t i o n of Table 10. Radical reactivities of c i s - and trans- isomers isomer radical c t # T°C more reactive isomer more stable isomer ref. methyl 0.5 65 trans trans (12) 2-butene c c i 3 - 2.4 cis trans ( ) phenyl 2.0 cis trans (37) di-t-butylethylene methyl .5.0 65 trans trans (12) Gl cis cis • (38) 1,2-dichloroethylene vinyl acetate .15 60 trans cis (40) polystyryl 0.15 60 trans cis (39) c rot ononi tri1e ethyl 0.74 polystyryl 1.1 60 60 trans cis cis cis methyl 0.16 65 trans trans (12) diethyl maleate diethyl fumarate polystyryl 0.05 vinyl acetate .06 60 60 trans trans trans trans (40) (40) * for reactions X R > " R* + k t R« + * • X Y X « \ Y k c - 4 9 -I s o m e r i z a t i o n , which i s d i s cus sed i n the l a t e r s e c t i o n . REACTIONS OF THE ETHYL RADICAL WITH AQRYLONITRILE AND METHACRYLONITRILE The r e a c t i o n s o f the e t h y l r a d i c a l w i t h a c r y l o n i t r l l e and m e t h a c r y l o n i t r i l e are summarized i n Tables 4 , 5 and 6 and F i g . 2.. I n the case of a c r y l o n i t r l l e , the r e s u l t s of t h i s work agree v e r y w e l l w i t h those obta ined by James and MacOallum (41) . The r e s u l t s obta ined by James and MacOallum had been c a l c u l a t e d on the assumption, ^3/^2 = 0 .136 , and were r e - c a l c u l a t e d u s i n g the newly found va lue of t h i s work, 0 .128 , i n the presence of a c r y l o n i t r l l e . The d i f f e r -ence between the two k 3 / k 2 v a l u e s , however, does not a f f e c t s i g n i f i c a n t l y the va lue s obta ined by James and MacOallum f o r the nate constants of the a d d i t i o n r e a c t i o n . The m a t e r i a l ba lances of t h e i r r e s u l t s are c o n s i d e r a b l y s m a l l e r than t h a t o f t h i s work and t h i s f a c t renders t h e i r va lue to ^ / k g ^ " i n s e n s i t i v e to a s m a l l e r r o r i n ^ 3 / k g . The e x p e r i -mental c o n d i t i o n s o f the two s t u d i e s d i f f e r e d i n the f o l l o w i n g r e s p e c t s ; (1) c o n c e n t r a t i o n s o f r e a c t a n t s , (2) l i g h t i n t e n s i t y , (3) r e a c t i o n t ime and (4) a n a l y t i c a l method. Thus, i t i s a g a i n confirmed t h a t t h e . r a t e constants are independent o f these exper imenta l c o n d i t i o n s and t h a t the r e a c t i o n mechanism i s v a l i d . The r a p i d a d d i t i o n o f the e t h y l r a d i c a l t o a c r y l o n i t r l l e and m e t h a c r y l o n i t r i l e rencer s the necessary a c e r t a i n cm 50 *° c o r r e c t i o n i n c a l c u l a t i n g the r a t e c o n s t a n t s . The concen-t r a t i o n o f the monomer i n each case I s v e r y s m a l l because o f the h i g h r e a c t i v i t y towards a d d i t i o n and the consump-t i o n o f the monomer may he too l a r g e to assume t h a t i t s c o n c e n t r a t i o n i s e f f e c t i v e l y constant throughout the r e -a c t i o n . T h e r e f o r e , the average c o n c e n t r a t i o n o f monomer was used f o r the c a l c u l a t i o n of the r a t e constant f o r a d d i t i o n . F i r s t an approximate va lue was c a l c u l a t e d f o r k 7 / k 2 ^ assuming no s i g n i f i c a n t consumptionj t h i s v a l u e was then used to c a l c u l a t e the f r a c t i o n of monomer con-sumed d u r i n g a d d i t i o n by the equations ^ i n i t . " ^ f l n . = Rc* X t x (1-MO f o r which we have ODm = 4 lnlt. + ^ f i n . ) The r a t e constants f o r the a d d i t i o n o f the e t h y l r a d i c a l t o a c r y l o n i t r i l e seem to f a l l o f f s h a r p l y a t temperatures lower than 4 5 ° 0 ; t h i s has been observed f o r some o ther subs t r a te s and probab ly r e s u l t s f rom. the appre-c i a b l e s t a b i l i t y of, the p r o p i o n y l r a d i c a l a t such tempera-t u r e s . The r e s u l t s o f James and MacCallum ( 4 l ) were r e c a l -c u l a t e d u s i n g the va lue ^ / k g = 0.128 and the average v a l u e f o r monomer c o n c e n t r a t i o n . S t a t i s t i c a l a n a l y s i s f o r a d d i t i o n t o a c r y l o n i t r i l e were c a r r i e d out on the r e s u l t s o f t h i s work and o f James and MacOallum as a group r e -s p e c t i v e l y and a l s o the combined r e s u l t s as a t h i r d group. - 51 -E 7 - | E 2 , 13 + log A7/Ag a c r y l o a i t r l l e....ms work 2.8 -1.75 4.8 ± .87 James and MacOallum 3.7 ± .73 5.3 ±, .41 combined, r e s u l t s 3.45 * .53 5.20 t .30 m e t h a c r y l o n i t r i l e 4.61 ± .67 5.76. ± , 0 . 4 1 The l i m i t s o f e r r o r s are c a l c u l a t e d a t the 5% p r o -b a b i l i t y l e v e l . A l t h o u g h the s tandard va lues d i f f e r a p p a r e n t l y s i g n i f i c a n t l y , the va lues o f probable e r r o r are too l a r g e to a l l o w d i s t i n c t i o n to be made between c o r r e -sponding parameters , so i t was necessary to go to the 10% p r o b a b i l i t y l e v e l to, o b t a i n a s i g n i f i c a n t d i f f e r e n c e i n the energy o f a c t i v a t i o n . E 7 - i E 2 13 + l o g A 7 / A | a c r y l o n i t r l l e 3.45 ± .44 5.20 * . 2 6 (combined r e s u l t s ) m e t h a c r y l o n i t r i l e 4.61 ± .56 5.76 ± .33 No s i g n i f i c a n t d i f f e r e n c e i s observed f o r the r a t e constants o f a d d i t i o n r e a c t i o n o f the e t h y l r a d i c a l between w i t h a c r y l o n i t r l l e and w i t h m e t h a c r y l o n i t r i l e ; both l y i n g W i t h i n the probable e r r o r a t the 50$ l e v e l . A t temperatures between 110°C and 45°0, however j, i t can be seen i n P i g . 2 t h a t r a t e constants f o r a d d i t i o n to a c r y l o n i t r l l e are d i s t r i b u t e d s l i g h t l y more h i g h l y than those to m e t h a c r y l o n i t r i l e a l though both r a t e constants cannot be d i s t i n g u i s h e d s i g n i f i c a n t l y . - 52 -REEATIVE REACTIVITY AND PATTERN OF SUBSTITUTION I t was found i n t h i s work t h a t r e a c t i v i t i e s o f sub-s t r a t e s towards the add i t ion .o f the e t h y l r a d i c a l d i f f e r l a r g e l y between the two groups; (1) c i s - and t r a n s -c r p t o h o n i t r i l e on the one. hand and (2) m e t h a e r y l o n l t r i l e and a c r y l p n i t r i l . e on the o t h e r . The l a t t e r group has va lues o f k f / k g ^ about 10 t imes g r e a t e r than those of the former . Th i s may be s imply cons idered to be due to the s t e r i c e f f e c t o f the methyl group o f c r o t p h o n i t r i i e l o c a t i n g on the c/ carbon atom; a v iew supported by the magnitude o f the va lues o f ^"j/k^. Moreover I t i s a w e l l known; ; f a c t thato(,j3 - d i s u b s t i t u t e d e thylenes are much l e s s r e a c t i v e f o r a r a d i c a l a t t a c k than mono-* or «><!,©(-di^substituted e t h y l e n e s ; p o l y m e r ! z a t l o n s I n p a r t i c u l a r monomers o f group (1) do not r e a d i l y undergo r a d i c a l homopolymeriza-t i o n . R e l a t i o n s between r a d i c a l r e a c t i v i t y and p a t t e r n o f s u b s t i t u t i o n have been s t u d i e d f o r s e r i e s o f compounds Of s t r u c t u r e s ; a R E K . and R E R R where R may represent any s u b s t i t u e n t . Szwarc and h i s cprwprkers have s t u d i e d the methyl a f f i n i t i e s o f v a r i o u s v i n y l monomers i n s o l u t i o n a t 65°C and found t h a t the r e l a t i v e r e a c t i v i t y d i f f e r s i n the o r d e r ; R. R R R R , R R ' R R R R R f o r example f o r s tyrene and i t s homologues (9) 2 .0 1.0 0.13 0.06 ( r e l a t i v e r e a c t i v i t y ) f p r methyl d e r i v a t i v e s of e thylene (11) = ^ >= > W > 1.6 1.6 1.0 0 .3 f o r a c r y l o n i t r i l e and i t s methyl d e r i v a t i v e s (7) ON ON y X 0 N x / ON 1.2 1.0 0.042 0.013 for methyl a c r y l a t e and i t s d e r i v a t i v e s (7) >= > > H > OOOMe OOOMe OOOMe OOOMe 1.3 1.0 0.06 0.01 I n t h i s wqrlc, a t 6 5 ° 0 , i t was found t h a t the r e -l a t i v e r e a c t i v i t y f o r a d d i t i o n of the e t h y l r a d i c a l i s i n o r d e r ; vs. A ON / ON y ON 1.0 0 .9 0 .07 - 54 -Although the difference of r e a c t i v i t i e s between acrylo-n i t r i l e and methacrylonitrile i s not slgnifleant,?.and;-both rate constants are not distinguished q u a n t i t a t i v e l y l y i n g within a probable error, t h i s work resulted i n a s l i g h t difference i n the order of r e a c t i v i t y f o r addition reaction of a c r y l o n i t r i l e and methacrylonitrile. In the r e s u l t s obtained by Szwarc and his co-workers, which were mentioned above, the difference' of r e a c t i v i t i e s . .>-R R between \— and X — increases i n order R / Me x / Me'- N , Me ^ ON ON ' OOOMe OOOMe Me Me > • Y> <P J>0% 60% 100% (Increment i n r e a c t i v i t y conferred by the second substituent) I t may be noted i n t h i s comparison that a polar effect seems to be an important factor determining the r e a c t i v i t y difference between R . and >= r= R R However, as probable errors are not given i n t h e i r . s t u d i e s , i t Is uncertain which of these increments are s i g n i f i c a n t . In p a r t i c u l a r , the polar effect of the second substituent i s co-operative i n the l a s t two examples, but not i n the f i r s t two. - 55 T h e r e f o r © , i t i s concluded t h a t , a l though the r e l a t i v e Me r e a c t i v i t y o f p > = and / = towards the a d d i t i o n oil o s of the e t h y l ; r a d i c a l appears to r ever se the o rder found f o r the a d d i t i o n o f the methyl o r the p h e n y l r a d i c a l s t o these monomers, the magnitude of the e f f e c t i n each case appears to be w i t h i n the range of probable e r r o r . Moreover a c r y l o -n i t r l l e has i t s enhanced r e a c t i v i t y i n pa r t to the e l e c t r o n -wi thdrawing p r o p e r t i e s o f the ON group. The CH^ group i s p r i m a r i l y an e l e c t r o n donat ing group, and i t I s perhaps s i g n i f i c a n t t h a t the OH^ group i n c i s - and t r a n s -c r o t o n o n i t r i l e and i n m e t h a c r y l o n i t r i l e appears t o r a i s e the energy of a c t i v a t i o n f o r a d d i t i o n from the v a l u e f o r a c r y l o n i t r l l e by about the same amount f o r each o f the methyl d e r i v a t i v e s . The s m a l l e r r e a c t i v i t y o f methacry lo-n i t r i l e i n comparison w i t h a c r y l o n i t r l l e i s c o n s i s t e n t w i t h the i d e a t h a t the great r e a c t i v i t y of both spec ie s towards the e t h y l r a d i c a l i s p r i n c i p a l l y due to a p o l a r c o n t r i b u -t i o n t o the t r a n s i t i o n s t a t e o f the a d d i t i o n r e a c t i o n . I n the r e a c t i o n s o f the e t h y l r a d i c a l w i t h c i s - and t r a n s - c r o t o n o n i t r i l e , m e t h a c r y l o n i t r i l e and a c r y l o n i t r l l e v . . the mean va lues o f 3 / k p were found as -.56. -CiS*"* Qrot033.0nltr JLlS • o ©. o a a * © * o o © o .© o o o © * o o o t0» trans- c r o t o n o n i t r i l e * • « « » © • ©©© :©©© ©* *© ©•0#136 IDlStllStCry'lOIli.tril© a o o o o © o ©»©©'©«; © • • ©.© o • • o o o a ©0©139 a c r y l o n i t r i l e • • • • • • ©o . © © © © « « © * « o©:©;©.o.©.©.©-©o © « 0 o 128 These va lues are not s i g n i f i c a n t l y d i f f e r e n t from the l i m i t i n g v a l u e of 0.12 suggested by B r i n t p n . a n d S t e a c i e (24 ) . James and S t e a c i e (18) have used the va lue 0.136 t o c a l c u l a t e the r a t i o o f ethane t o e t h y l e n e . I t has been observed t h a t the d i f f e r e n c e I n these va lues between 0.12 and '0*1.4-has n p ; s i g n i f i c a n t e f f e c t on the r a t e constant o f a d d i t i o n . The p o s s i b l e r e a c t i o n s which may r a i s e the apparent va lue of 3 A 2 are l i s t e d as f o l l o w s ; (a) i n the p h o t o l y s i s o f d i e t h y l ketone by. the r e a c t i o n • 0 2 H 2 . 0 0 ' 0 2 H 5 — 0 2 H 4 + 00 + 0 2 H 5 . which i s not u s u a l l y a p p r e c i a b l e below 2 5 0 ° 0 . (b) i n the p h o t p l y s i s o f d i e t h y l ketone i n the presence of subs t r a te s by r e a c t i o n s o f the t y p e : 0 2 H 5 - OHR - OR'ON + ; d 2 % " ~> ° 2 H 5 ~ G H R •+. ° 2 H 4 Such r e a c t i o n s produce an excess of e thy lene which r a i s e s k / the apparent va lues o f 3 / k 2 ; such a r i s e i s not de tec ted i n the systems of t h i s I n v e s t i g a t i o n except a t temperatures; h i g h e r . t h a n those used f o r q u a n t i t a t i v e measurement. (c) S ince spine methathes is presumably o c c u r , and the e f f e c t on k 3 / k p i s not l a r g e ; - 57 -0 H 2 = 0 ' . + * 0 2 H 5 ^ 0 H 2 = 0 5 + 0 2 H 4  N ON N ON f o r the m e t h a c r y l o n i t r i l e and c r o t o n Q n i t r i l e s . ABSOLUTE VALUES OF E^ AND A ? The r e s u l t s obta ined i n t h i s work are not complete wi thout a statement of va lues f o r E^ and A^.. The va lue s may be c a l c u l a t e d u s ing the ex pre s s i o n f o r kg (42) . k 2 = 5.06 x I O " 1 0 exp(-2000 ± 1000)/RT cm? m o l " 1 sT1 K c a l / m o i e c i s - c r o t o n o n i t r i l e 0.81 5.9 1.2 t r a n s - c r o t o n o n i t r i l e 0.83 5.7 ± 1.4 m e t h a c r y l o n i t r i l e 12.8 5.6 + 1.2 a c r y l o n i t r l l e 3.6 4.4 1.0 (combined) However, the probable e r r o r s i n v a l u e s A and E are i n c r e a s e d by t h i s o p e r a t i o n , thus f o r purposes o f com-p a r i s o n , the r e l a t i v e v a l u e s o f A and E are p r e f e r a b l e . OOREELATION BETWEEN VALUES OF k 7 / k | AND OF METHYL. AFFINITY Szwarc and h i s co-workers have I n v e s t i g a t e d the methyl a f f i n i t i e s o f many o l e f i n i c compounds a t 65°0 i n i s o -octane s o l u t i o n and the e t h y l a f f i n i t i e s o f a few, and have demonstrated a l i n e a r r e l a t i o n s h i p between them. Conse-q u e n t l y a comparison of r a t e constants must s u f f i c e and should not Introduce v e r y much e r r o r as the v a r i a t i o n i n A - 58 -f a c t o r f o r a t t a c k by the methyl r a d i c a l should f o l l o w r o u g h l y the same pat tern , as f o r a t t a c k by the e t h y l r a d i c a l . The work o f Szwarc and h i s co-workers d i f f e r s i n two re spec t s from t h i s l n y e s t i g a t l o h ; (a) the m e t h y l , r a t h e r than the e t h y l , r a d i c a l has been chosen f o r the genera l survey of r e a c t i v i t y , and (b) the r e a c t i o n s are s t u d i e d i n s o l u t i o n . Table 11 shows the v a l u e s of the methyl a f f i n i t y and ^T / k g 8 a t 65°0 and the l o g a r i t h m s o f those va lues were p l o t t e d i n P i g . 5. The p o i n t s were observed to l i e c l o s e l y about a l i n e of u n i t g r a d i e n t . I t was concluded t h a t the methyl and the e t h y l r a d i c a l possess equa l I n t r i n s i c r e -a c t i v i t y and t h a t the r a t e constants f o r the a d d i t i o n of these r a d i c a l s to a s i n g l e s u b s t r a t e are probably I n approx imate ly constant r a t i o . As, the l o g a r i t h m s o f the methyl a f f i n i t i e s are l i n e a r l y r e l a t e d to those o f the e t h y l a f f i n i t i e s , t h i s i s e q u i v a l e n t t o a c o r r e l a t i o n between the r a t e of a d d i t i o n o f the e t h y l r a d i c a l i n s o l u -t i o n and i n the gas. phase. A l i n e of u n i t g r a d i e n t has been drawn and the s c a t t e r o f p o i n t s about the l i n e i s s m a l l enough to support the l i n e a r r e l a t i o n . Th i s c o r r e l a t i o n i m p l i e s t h a t the methyl r a d i c a l i n s o l u t i o n and the e t h y l r a d i c a l i n s o l u t i o n or i n the gas phase have s i m i l a r i n t r i n s i c r e a c t i v i t i e s . T h i s c o n c l u s i o n I s i n accord w i t h the p r e d i c t i o n t h a t r e p u l s i o n between a Table 11. Correlation of the rate constants for the addition of the ethyl radical with the methyl a f f i n i t i e s of various substrates, each at 65°C. Substrate 13 + log(k ? / k 2 ) i o g(Me. Aff.) octene-1 0.56 l.H* 2,5-dimethylhexadiene 0.92 1.33 vinyl acetate 0.91 1.57 2, 4, 4-trimethylpent ene 1.06 1.56** cis-crotononitrile 1.38 1.87*** ... trans-crotononitrile 1.55 1.87*** cyclohexadiene-1,3. 2.16 2.82 styrene 2.30 2.91 . 2,3-dimethylbu.tadiene-l, 3 2.71 3.35 methacrylonitrile 2.76 3.33 acrylonitrile 2.94 3.24 * the value for heptene-1 ** the value for isobutene *** cis and trans mixture Fig. 5. Correlation of the rate constants for the addition of the ethyl r a d i c a l with the methyl a f f i n i t i e s of various substrates, each at 65°C. O J t h i s woric„ - 61 -methyl r a d i c a l and a s u b s t r a t e should not d i f f e r appre-c i a b l y from the r e p u l s i o n f o r an e t h y l r a d i c a l (43). THE POLYSTYRYL RADICAL C o p o l y m e r i z a t i o n of c i s - and t r a n s - c r o t o n o n i t r i l e w i t h s tyrene was i n v e s t i g a t e d i n t h i s work a t 60°G i n the l i q u i d phase j- which w i l l be d i s cus sed i n the next s e c t i o n . As mentioned i n the i n t r o d u c t o r y p a r t , i n the c o -p o l y m e r i z a t l o n of two monomers M^ and Mg the p o s s i b l e propaga t ion r e a c t i o n s a r e ; + M x - k l l + Mg -^ P 2 - k 1 2 V" + r\ - * 21 P 2 . + P 2 -^  V k 2 2 where P^* and Pg* repre sent growing polymer r a d i c a l s w i t h M-^  and Mg r e s p e c t i v e l y as t e r m i n a l u n i t s . The r e a c t i v i t y r a t i o s a r e de f ined a s : r x = k l l / k 1 2 add r g .= k 2 2 / k 2 1 A l f r e y and P r i c e (44) i n t e r p r e t e d data on eopo lymer lza t ions o f many v i n y l monomers i n terms o f resonance Q and e l e c t r i c a l e f a c t o r s c h a r a c t e r i s t i c of the monomers as f o l l o w s , -..62 -r x = k l l A 1 2 = Q l / Q 2 exp j - e 1 ( e 1 - e 2 ) | r 2 = k 2 2 A 2 1 = Q2 / Q 1 exp { - e g i ' e ^ e ^ j P r i c e and Schwan, (4S -), however, have reformed t h e i r Q-e. scheme by r e l a t i n g these a r b i t a r y Q ande numbers to more fundamental and s i g n i f i c a n t c h a r a c t e r i s t i c s of the monomers i n the f o l l o w i n g way; Q = exp | RT | e = £ / ( r D R T ) * For the r e a c t i o n I n v o l v e d ; + 0H2=0H ' OHg-pH-OHg-OH R 2 % R 2 (M 2 ) ( P 2 « ) q. r epre sent s the r e l a t i v e resonance s t a b i l i z a t i o n con-f e r r e d on the new r a d i c a l P 2 , £. may be represented as the charge induced by R 1 o r R 2 on e i t h e r o f the carbon forming the new C-C cova lent bond I n the t r a n s i t i o n , r represent s the d i s t a n c e s e p a r a t i n g these charges i n the t r a n s i t i o n s t a t e and D the e f f e c t i v e d i e l e c t r i c constant between them. Thus, i t i s shown t h a t r x = exp j-C^-Hlg) /n) e#p { - 7 . 2 3 x l 0 2 0 e 1 ( ; ^ - % . ) / R T } or RT logC1/^ ) = ( q 1 - q 2 ) + 7 .23 x l O 2 0 ^ ^ - ^ ) / V w v*0H« —CH • I R l 63 -. The equat ion d e r i v e d by Bamford, J enkins and Johnston , a l s o expresses r e a c t i v i t y i n terms of p o l a r and n o n - p o l a r e f f e c t s (46) l o g k g = l o g k T + vttf + p (b) The r a t e constants k g and k T r e f e r r e s p e c t i v e l y to the r e a c t i o n of a g i v e n r a d i c a l RCH 2-0HX w i t h a subs t r a te S and to metathes i s o f the same r a d i c a l w i t h t o l u e n e , (T i s the Hammett constant f o r the group X , and e< and /9\ a re constants f o r the s u b s t r a t e S . The q u a n t i t y C$ i s a measure o f the extent to w h i c h the r e a c t i o n r a t e i s i n f l u e n d e d by p o l a r s u b s t i t u e n t s . I f e i t h e r ol or i s z e r o , the equat ion r e -duces t o l o g k s = l o g k T + @ The equat ions (a) and (b) a r e , to a l a r g e e x t e n t , e q u i v a l e n t , and the r e a c t i v i t y r a t i o s c a l c u l a t e d from the equat ion (a) can be used t o c a l c u l a t e va lues o f p i n the equat ion ( b ) , which may be w r i t t e n i n the form l o g ( X / r l ) = l o g ( k T / k i : L ) +^+f Thi s has been done f o r a number of monomers i n Table 12. • I s s tyrene and a temperature of 6 0 ° 0 has been adopted. The v a l u e o f s' f o r p o l y s t y r y l i s known to be -0 .01 (46 ) . The va lue s o f q 2 and £ 2 have a l s o c a l c u l a t e d by the equa t ion (a) and shown i n Table 12 . 64 '-The va lues o f l o g ( ' r j ) are p l o t t e d aga in s t the va lues o f 13 + l o g ( k 7 A 2 ^ ) a - t 6 0 ° 0 f o r those monomers i n F i g . .6, and a l i n e o f u n i t s lope has been drawn, show|$g£ t h a t the e t h y l r a d i c a l and the p o l y s t y r y i r a d i c a l do not d i f f e r a p p r e c i a b l y i n i n t r i n s i c r e a c t i v i t y . I n order t o t e s t the v a l i d i t y o f these c o r r e l a t i o n s the expected va lues o f f o r methyl a c r y l a t e and methyl methacry la te were c a l c u l a t e d u s ing the va lue s o f methyl a f f i n i t i e s (7) a t 6 5 ° and of r x (40) a t 60°G from F i g . 11 and 12 . M e t h y l a c r y l a t e 1030 643 0.75 733 M e t h y l m e t h a c r y l a t 2 4 4 0 ? 6 4 Q ^ ? 6 4 The e r r o r of t h i s type of c a l c u l a t i o n i s f a i r l y l a r g e but these va lues of ^J/^* obta ined from ^ 2 / ^ are rea sonab ly i n agreement w i t h those from r-^. A p p l y i n g Szwarc ' s concept of i n t r i n s i c r e a c t i v i t y , i t i s concluded t h a t the e t h y l and p o l y s t y r y i r a d i c a l s have equal i n t r i n s i c r e a c t i v i t y . As i t has been con-cluded above t h a t the I n t r i n s i c r e a c t i v i t y o f the e t h y l r a d i c a l i n the gas phase I s equal t o t h a t o f the methyl r a d i c a l i n the l i q u i d phase, I t would be expected t h a t methyl and p o l y s t y r y i r a d i c a l s should have equal i n -t r i n s i c r e a c t i v i t i e s . Table 12. Correlation between the rate constants for the addition of the ethyl radical and the monomer reactivity ratios for the copoly-merization of various monomers with styrene, both at 60°C. monomer 13 + log k„A„ log ( l / O (Z.6) 6 octene-1 (18) hexane-1 (45) 0.49 -1.95 0 2.85 vinyl butyl ether (41) 0.77 vinyl isobutyl ether (45) -1.67 0 2.82 heptyne-1 (18) hexyne-1 (45) 0.25 -1.98 0 3.13 a l l y l alcohol (21) a l l y l acetate(51b) 0.65 -1.67 0 3.13 2.3-dimethylbutadiene-l,3 (20) 2.66 butadiene (51) 0.33 0 5.13 acrylonitrile 2.92 0 . 4 0 (50) 0 .03 5.17 methacrylonitrile 2.73 0.52 (51a) 0.02 5.40 cis-crotononitrile 1.37 -1.23 0.02 trans-crotononitrile 1.50 -1.28 0.02 2,44-trimethylpent ene(18) 0.93 isobutene (45) -1.85 0 4.80 styrene (19) 2.26 0.00 0 2.95 The f i r s t compounds of pairs are the substrates for which k^/k^ have been measured. The second compounds are related monomers for which values of r^ have been measured. I I I — I 1——> I I I I I I Figo 6. Correlation of the addition rate constant with the rate constant for the addition of the polys t y r y i r a d i c a l , each at 60°Co ^ * other workers ^) ; measured inchis work . y f l &nd weosu-red. inth\s work. - 67 0OPOLYMERIZABILIT Y OF CROTONONITRILE The r e l u c t a n c e o f 1 , 2 - d i s u b s t I t u t e d e thylenes to undergo r a d i c a l homopplymerlzat lon i s so genera l as to i n v i t e s p e c u l a t i o n concerning the reasons f o r t h i s be-h a v i o u r . Almost a l l o f the systems o f t h i s type which have been s t u d i e d up to now, e x h i b i t r g va lues o f z e r o , w i t h i n exper imenta l e r r o r . T h i s i s probably the conse-quence o f s t e r i c h indrance r a t h e r than the r e s u l t o f some s o r t o f ' , c a n c e l l i n g w o f the In f luence o f one sub-s t i t u e n t group by the o t h e r , because unsymmetrlcal 1 , 2 - d l s u b s t i t u t e d compound, such as c r o t o n i e e s t e r s , as w e l l as symmetical 1 , 2 - d I s u b s t i t u t e d monomer, such as d i c h l o r o e t h y l e n e , show thi s , r e l u c t a n c e f o r s e l f - a d d i t i o n to the same e x t e n t . Three d imens iona l diagrams, however, b r i n g out more c l o s e l y the a c t u a l s p e c i a l arrangement o f the atoms I n c o p o l y e e r i z a t l o n r e a c t i o n s . The products o f r e a c t i o n s H I (& ) AAA/ (jj X H and ( (b) -v^o i H are sketched i n F i g . 7a w i t h the four c h a i n atoms arranged I n a p l a n e . A c t u a l l y , these f o u r carbon atoms must not n e c e s s a r i l y be i n one plane because o f ^ p o s s i b l e r o t a t i o n H I X / / X H X Nc=c 7 / \ X H H H 0=0 X X ~ 6 8 -about the carbon-carbon s i n g l e bonds. As one l o o k s at a diagram such as shown i n F i g . 7a s t e r i c i n t e r f e r e n c e be-tween s u b s t i t u e n t on carbon atoms 1 and 3. does not seem so s u r p r i s i n g . However, the e f f e c t cannot be abnormal ly l a r g e (except f o r v e r y bu lky groups) s i n c e compounds of t h i s type are a c t u a l l y q u i t e s t a b l e ( a f t e r they are formed) . I t seems l i k e l y t h a t i n the t r a n s i t i o n s t a t e f o r r e a c t i o n (a) the s t e r i c I n t e r f e r e n c e i s more s e r i o u s than i n the f i n a l p r o d u c t . L e t us cons ider a s k e t c h of the r e a c t a n t s and products i n g e n e r a l i z e d case where 1 , 2 , 3 , and 4 r epre sent carbon atoms; a , b , c , d , e , f , g , and h represent v a r i o u s s u b s t i t u e n t s ; and r , d e s i g n a t e s the f ree r a d i c a l o r b i t a l ( F i g . 7 b ) . I n the process o f r e -a c t i o n , the angle de f ined i n F i g . 7blby C^-Cg-r i s con-v e r t e d from the 9 0 ° p l a n a r angle o f the c h a i n end r a d i c a l to the 1 0 9 ° t e t r a h e d r a l bond angle C-j^Cg-C^ ( F i g . 7b2) and the bond angles o f atom 3 are a l t e r e d as w e l l . I n the monomer, before a t t a c k , the bond angles e - 0 ^ - 0 ^ and f - C j - O ^ are c o p l a n a r , and approx imate ly equal to 1 2 0 ° . The It e l e c t r o n o r b i t a l , which l a t e r couples w i t h ; t h e a t t a c k i n g f r e e r a d i c a l , i s d i r e c t e d normal to the plane d e f i n e d by atoms e, ff q and 0^. Dur ing the r e a c t i o n , the s u b s t i t u e n t s e and f f o l d back i n t o a t e t r a h e d r a l c o n f i g -u r a t i o n a l t h o u g h the bonds 0^-0^, C^- 9 . , and G^-Jv remain c o p l a n a r . I n the t r a n s i t i o n s t a t e , these angles and the bond d i s t a n c e s presumably have i n t e r m e d i a t e v a l u e s , - 69 -e . g . v the angles G^-Cg-G^ and .Og-C-j-O^ are Intermediate between 90° and 109° and the distance between carbon atom 0^ a h d G^ i s intermediate between the double bond and s ing le bond dis tances . I f we d i s t o r t the bond angles i n the product r a d i c a l (P ig . 7b2) toward the form of the t r a n s i t i o n s ta te , i t can be seen that groups l i k e b and -f-are forced closer together, to a point where considerable .ran- dea r ,tfaals.^-repulsion",may. pc.pur, , Thus, the s t e r i c I n -terference would appear to be much greater i n the t r a n s i -t i o n state than i s Indicated by a s t ruc tua l formula or model of the product r a d i c a l i t s e l f . In the case of c i s - and t rans- c ro tonon i t r i l e i t . was found that the value of r.g was zero, no s e l f - a d d i t i o n of c ro tonoh i t r i l e taking place. Homopolymerlzation of c ro tonon i t r i l e was attempted using benzoyl peroxide as an i n i t i a t o r (2 x 10" mole/ l ) for ten to twenty hours at 65°0 , but no polymer was obtained. The values ofYr for c i s - and t r ans - - c ro tonon i t r i l e were found to be 17 * 0 . 3 and 19 ± 0 . 3 r espec t ive ly at 60°G and these values are much higher than the corresponding Values for mono- or 1 ,1 -d isubs t i tu ted ethylenes; namely 0 .41 for a c r y l o n i t r l l e (50) and 0 .30 for methacry lon i t r i l e (51) . This fact can be interpreted as s t e r i c hindrance, using the model pro-posed above for the t r a n s i t i o n s ta te . 70 -Table 13 shows some.; co l lec ted resu l t s of copolymer-i z a t i o h studies of 1,2-dIsubsti tuted ethylenes with, styrene at 60°C. In most eases i t i s seen that r 2 values are e i ther zero or very sma l l . Moreover, np r e l a t ionsh ip or. co r r e l a t i on between r e a c t i v i t i e s , s t a b i l i t i e s and geometry of c i s - and t rans- isomers i s apparent. Qual i ta t ive , experiments on the c.opolymerizatldn of c r o t o n o n i t r i l e wi th a c r y l o n i t r i l e "9- v i n y l chlor ide and styrenes, r e spec t ive ly , have been performed (48) at various concentrations of two monomers. These data are shown i n Table 14 i n comparison wi th those of t h i s work. I t can be seen that- both resu l t s of copolymer!zatlon'..of c ro tonon i t r i l e wi th styrene are i n good agreement, a l -though the i r , experimental conditions were not stated i n the communication. I t must be noted, In Table 14, that the p o l y a c r y l o n i t r l l e and the p o l y v i n y l chlor ide r ad ica l s each react more r e a d i l y than the p o l y s t y r y i r a d i c a l i n respect to '.addition.; to c r p t p n o n i t r i l e , I . e . , k 1 2 . is greater i n oases of a c r y l o n i t r i l e and v i n y l chlor ide than i n the case of styrene; for reac t ions , M« + M —» M* k x l M* + crpto-OH —=> croto-0H« k 1 2 .However, there are several factors here Including the r e -a c t i v i t i e s of M, (k-.-il for the determination of the / H X i Fig. 7a. Addition product of 1,2-disubstituted ethylene, ( I ) a t r a n s i t i o n state c dL 0 . -6- f e (II) a product r a d i c a l Pig.7b. Sketch of the t r a n s i t i o n state of the addition of an athylenic monomer to a free r a d i c a l . Table 13. Copolymerization of 1,2-disubstituted ethylenes with styrened^) at 60°C cis-dichloroethylene trans-diehloroethylene M a l e o n i t r i l e Fumaronitrile Diethyl maleate Diethyl fumarate Dimethyl maleate Dimethyl fumarate r l 210± 15 37 ± 3 .19 ± .03 .19 ± .03 -6.52 ± .5 .30 ± .02 8.5 i .2 .21 ± .02 Diethyl ehloromaleate 2.5 c i s - c r o t o n o n i t r i l e 17 ± .3 trans-crotononitrile 19 ± .3 *2 0 0 0 0 .07 .01 .03 .025 0 0 more reactive^ isomer trans no d i f . trans trans more stable isomer c i s trams trans trans ref, (39) (39) 140) (39) c i s C I S Table 14. Copolymerization of crotononitrile with other monomers. Monomer Mole fraction of crotononitrile i n the i n i t i a l monomer mixture Mole fraction of crotononitrile i n copolymer acrylonitrile .60 .40 .25 .07 vinyl chloride .50 .40 .30 .20 .10 .26 .21 .16 .12 .08 styrene .60 .40 .07 .04 styrene* .94 .88 .79 .74 .59 .52 .41 .26 .27 .19 .14 .11 .07 .06 .04 .03 * indicates the result of this work at 65°C. The others are from a private communication by Thompson, U.C.C.' - 73 monomer .r e a c t i v i t i e s ; i n . the copolymerization '.study. In general, i n the study of copolymerization reaction, i t has been established that the monomer r e a c t i v i t i e s are controlled j o i n t l y by resonance and polar e f f e c t s . I t has been found that a v i n y l monomer i n which the double bond i s conjugated with some other unsaturated group; - 0 - R ^0 =f I -<f~\ - 0 = G. etc. O w i l l exhibit a greater r e a c t i v i t y i n copolymerizatlon than a monomer with noh conjugated double bond, such as propy-lene,- v i n y l chloride, v i n y l acetate and others. This fact can be explained Aterms of the resonance s t a b i l i z a t i o n of the adduct r a d i c a l which, i s formed by the addition, of such a conjugated monomer. The degree of resonance s t a b i -l i z a t i o n conferred by a given r a d i c a l Is much larger i n the r a d i c a l than In the monomer from which I t i s derived. For example, styrene may have resonance structures of GH2 = GH •OH.im OH CHg = OH etc, 6 6 9 (i) (ii). (m) but i t i s clear that structures (II) and (III) are of considerably higher energy than ( I ) . On the otherhand, the p o l y s t y r y l r a d i c a l has resonance structures of <_^, /\, -GH <f-> etc. - 74 -and i s a resonance hybrid of the structures which have very s i m i l a r energies. And i t i s known that greater resonance s t a b i l i z a t i o n energy of an adduct r a d i c a l gene-r a l l y lowers the energy of a c t i v a t i o n . The e lect ron donating or accepting character of a substi tuent i n a monomer i s another Important factor con-t r o l l i n g the r e a c t i v i t y of the monomer. For example, In copolymerization of a c r y l o n i t r l l e wi th styrene, because of electron-donating character of the phenyl group of styrene there i s an excess of e lec t ron .density at the free r a d i c a l 0 of the p o l y s t y r y l r a d i c a l , and on the other hand there i s a def ic iency of e lec t ron density at the v i n y l carbons of a c r y l o n i t r l l e . In such a pa i r of monomers, cont-r i b u t i o n of i o n i c forms to the t r a n s i t i o n state accelerates the rate of reac t ion by lowering the energy of the t r a n s i -t i o n s ta te . According to these theories c ro tonon i t r i l e might be expected to have a h i g h e r ; r e a c t i v i t y wi th the p o l y s t y r y l r a d i c a l rather than wi th the p o l y a c r y l o n i t r l l e and the po ly-v i n y l chlor ide r a d i c a l s . However, i t was found (48) that the p o l y v i n y l chlor ide r a d i c a l could add more r a p i d l y than the. p o l y s t y r y l r a d i c a l to c r o t o n o n i t r i l e . Most probably the unfavorable polar effect i n the v i n y l chlor ide r a d i c a l add i t ion i s more than compensated - 75 -by the high general-•react ivi ty; of t h i s r a d i c a l i n compari-son wi th the p o l y s t y r y i r a d i c a l . A l f r e y and P r i ce (44) have developed a semi-quanti-t a t i v e expression for the r e a c t i v i t y of v i n y l monomers,, and they s tar ted t h e i r d iscuss ion wi th the equation k l 2 = A 1 2 e ( ' P l + *2 * V2) (a) where p^ and q 2 are the terms concerning the resonance effect and and e 2 r e la te to the polar character of the two monomers. The equation (a) i s a. modified form of the Arrhenius equation k = A e " ^ R T . The value of A 1 2 „ which i s concerned wi th the c o l l i s i o n e f f i c i e n c y , must be d i f ferent s l i g h t l y for every i n d i v i d u a l monomer, however, they assumed that A 1 2 values for various v i n y l monomers are not s i g n i f i c a n t l y d i f fe ren t , and they s i m p l i f i e d the equation (a) k 1 2 = P-jQg e e , e i (b) where P^ Is equivalent to p^ and Q 2 i s the s p e c i f i c r e -a c t i v i t y of the monomer 2 and equivalent to q 2 . A 1 2 Is included i n these terms as a constant. Therefore, -5i ve^e,r^ ( c ) 1 k i p ~ P i Q p e ' e , e i Q' L12 rr"2 This r e l a t i o n so ca l l ed "Q-e scheme" developed by Pr ice and h is co-workers (44) , has been used ^p;j account/; Of or monomer r e a c t i v i t y of var ious v i n y l monomers. - 76 -However, In the case of copolymerizatlon i n which one or both two monomer are 1,2-dIsubsti tuted ethylenes, the r e a c t i v i t y r a t i o does not seem to fo l low the Q-scheme as i s seen i n the case of oopolymerization of c r o t o n o n i t r i l e . The Q- Z scheme seems to be no longer appl icable In the simplest form since, the value of A^g f o r a 1 ,2-disubst i tu ted ethylene must d i f f e r s i g n i f i c a n t l y from that of a i , l - d l - or mono-substituted ethylene be-cause of i t s s t e r i c e f fec t . Therefore i t i s concluded that although the Q-scheme i s not d i r e c t l y appl icable i n i t s present form for 1 ,2-dlsubst i tu ted monomers. A simple modif ica t ion of the equation (h) for the s t e r i c effect would seem feas ib le on the basis of the r e su l t s of t h i s Inves t iga t ion . The po lymer l zab i l i t y of a 1 j2-d lsubs t i tu ted ethylene was discussed on the basis of the r e su l t so f t h i s work. I t i s concluded i n the case of copolymerizatlon of croton-o n i t r i l e , that the s t e r i c effect rather than resonance and polar effects controls the copolymerizatlon r eac t ion , and a lso that the simple r e a c t i v i t y of a polymer r a d i c a l seems to be dominant over resonance and polar e f fec ts . ISOMERIZATION OF CIS - AND: TRANS ?° OROTONONITRILE During the photolys is of d i e thy l ketone In the pre-sence of e i ther of the pure geometrical Isomers of - 77 -c r o t o n o n i t r i l e i n the gas phase, i t was observed'.that a small amount of interconvers ion of the c i s - and t rans-c ro tonon i t r i l e was taking place. As the o r i g i n a l quanti ty of c ro tonon i t r i l e i s very small i n the gas phase reac t ion , I t was d i f f i c u l t to obtain quant i ta t ive r e su l t s for the i somer iza t ion reac t ion . The data* obtained i n the gas phase are shown below, for the reac t ion at 125°6 . Time (mih.) % c i s produced from i n i t i a l l y 100$ trans $ trans from i n i t i a l l y 100$ els 15 30 50 600 . . . u n d e t e c t a b l e . v e r y small The concentrations of reactants were the same as those given i n Table 3, and the r a t i o of the concentration of d i e t h y l ketone to the concentration of c ro tonon i t r i l e was 2 .5 . * I t was d i f f i c u l t to obtain accurate r e su l t s because the peak due to d i e t h y l ketone p a r t i a l l y over-lapped that of c i s - c r o t o h o n l t r i l e i n the analys is on a gas chromatograph,. A 2 meter long column A was used i n tnts''"'analysis" at'" : '120°0. I t was found afterwards that a 4. meter long column R could separate d i e t h y l ketone and c i s -c ro tono-n i t r l l e at 120°0 and th i s was applied for the fo l lowing experiments. - 78 -In order to obtain more quantitative r e s u l t s , some Investigations f o r the photosensitized Isomerization were carried out i n the l i q u i d phase i n the presence of d i e t h y l ketone. The r e s u l t s are summarized i n Table 7 and Pig. 4 . Since both i n the gas and i n the l i q u i d phase very l i t t l e isomerization took place i n the absence of ethyl r a d i c a l s , I t i s probable that the photosensitized isomerization pro-ceeds by a r a d l o a l mechanism In both phases. Most pro-bably the isomerization and addition reactions are c l o s e l y r e l a t e d , the l a t t e r being i n part r e v e r s i b l e ; °2H5- + V ^ 0 N ^ °i^5 ^ ^ /F=^OT + ° 2 H 2 ' A s i m i l a r mechanism has been proposed by Siv.ertz f o r the geometrical isomerism which accompanied by the addition of the RS» r a c i c a l to cis-trans isomers ( 4 9 ) . The r e s u l t s obtained i n the l i q u i d phase indicate that the c i s isomer produced the trans isomer more r a p i d l y than the trans gave the c i s isomer under the same experi-mental conditions and t h i s was observed a f t e r 10 hours reaction. On the other hand, the r e l a t i v e thermal s t a b i l i t y of c i s - and trans- orotononitrile was also investigated. Results indicate that the c i s isomer i s thermodynamically more stable than the trans. The equilibrium state was not obtained i n t h i s experimental conditions, but approximate - 79 -e q u i l i b r i u m constants were c a l c u l a t e d f o r the r e a c t i o n t r a n s -p=£ c i s . CcisD 1.7 a t 260°G K e < 1 , = ctransj 2 . 3 a t 190 °0 whence, „ However, more q u a n t i t a t i v e exper imenta l work i s needed b e f r r e t h i s problem can be f u l l y d i s c u s s e d . Dur ing t h i s thermal i s o m e r i z a t i o n r e a c t i o n s o f c i s -and t r a n s - c r o t o n o n i t r i l e i t was observed t h a t a l l y l cyanide was produced as a r e s u l t s o f a molecu la r a r range-ment r e a c t i o n , and i t i s i n t e r e s t i n g t h a t c i s - c r o t o n o -n i t r i l e y i e l d e d about 5 t imes more a l l y l cyanide than the t r a n s ; 3.6$ by the c i s and 0.7% by the t r a n s . T h i s r e a c t i o n i s p o s s i b l y an example of ac id-base c a t a l y s i s , the a c i d be ing e i t h e r c r o t o n o n i t r i l e i t s e l f or some substance d e r i v e d from the r e a c t i o n v e s s e l a t h i g h temperatures . The g r e a t e r thermal s t a b i l i t y o f the ois- i somer- of c r o t o n o n i t r i l e f i n d s a p a r a l l e l i n the g r e a t e r thermal s t a b i l i t y o f the c i s Isomer o f the 1 ,2-dIha logeno-ethylenes (£3') ('.28), but i s an e x c e p t i o n t o a genera l r u l e t h a t the t r a n s isomer should be the more s t a b l e . No ex-p l a n a t i o n f o r the r e l a t i v e thermal s t a b i l i t y o f c i s - and t r a n s - c r o t o n o n i t r i l e has been found, but i t may be d i s -cussed on the ba s i s o f some e l e c t r o s t a t i c i n t e r a c t i o n - 80 -between the -C=N and the -0H^ groups. To summarize t h i s study of c i s - t r ans isomeri'.zations ™ ^ C N (1) For the l i q u i d phase reac t ion photosensit ized by d i e t h y l ketone: let > kc af ter 10 hours, e . g . , af ter 10 hrs . 1.2 (2) For the l i q u i d phase uncatalyzed thermal r eac t ion kc y k t , Kc = 1.7 and 2.3 at 260° and 190°0 r e spec t ive ly , where Kc = C0^83^ -£ t r a n s } (3) i n the case of (2) , between the reactions at 260°0 CN > >—ON 7 ON _^ >—CN k 2 ^ and ^ l / k c - 0.01 and ^S/kfc = 0.09 - 81 -C O N C L U S I O N S V a l u e s o f t h e e n e r g y o f a c t i v a t i o n f o r c i s - a n d t r a n s -c r o t o n o n i t r i l e a n d m e t h a c r y l o n i t r i l e w e r e i n d i s t i n g u i s h a b l e , b u t w e r e s i g n i f i c a n t l y h i g h e r t h a n t h a t f o r a c r y l o n i t r i l e . I t a p p e a r e d t h a t t h e m e t h y l g r o u p i n c i s - a n d t r a n s - c r o t o -n o n i t r i l e a n d i n m e t h a c r y l o n i t r i l e r a i s e d t h e e n e r g y o f a c t i v a t i o n for a d d i t i o n f r o m t h e v a l u e f o r a c r y l o n i t r i l e b y a b o u t s a m e a m o u n t f o r e a c h o f m e t h y l d e r i v a t i v e s . L o w e r v a l u e s o f A f a c t o r f o r e l s - a n d t r a n s - c r o t o n o -n i t r i l e w e r e d u e t o t h e m e t h y l g r o u p l o c a t e d : ; o n t h e s e c o n d c a r b o n a t o m o f t h e d o u b l e b o n d . T h e r a t e c o n s t a n t s f o r t h e a d d i t i o n o f t h e e t h y l r a d i c a l i n t h e g a s p h a s e w e r e l i n e a f t i y r e l a t e d t o t h o s e o f t h e m e t h y l a f f i n i t i e s i n s o l u t i o n a n d o f p o l y s t y r y i r a d i c a l i n t h e l i q u i d p h a s e . R e a c t i v i t y d i f f e r e n c e s b e t w e e n c i s a n d t r a n s I s o m e r s f o r a d d i t i o n o f v a r i o u s f r e e r a d i c a l s c o u l d n o t b e e x p l a i n e d . O l s - c r o t o n o n l t r l l e w a s f o u n d t o b e t h e r m o d y n a m i c a l l y m o r e , s t a b l e t h a n t r a n s - c r o t o n o n i t r i l e . - 82 -REFERENCES 1. Hardwick, T. J . J . Phys. Chem., 64 1623 (I960). 2. Hardwick, T. J . i b i d . 66 291 (1962). 3 . Jennings. K. R. and Cvetanovic, R. J . J , Chem. Phys. 35 No. 4 1233 (1961). 4. Jensen, Kharasch and Urry. Science, 102 128 (1945). 5. Idem. J . Amer. Chem. S o c , 68; 154 (1946). 6. Idem, i b i d . , 6£ 1100 (1947). 7. S t e f a n i , A. P., Herk, L. aid Szwarc, M., J . Amer. Chem. S o c , 83 4732 (1961). 8. Szwarc, M., and Levy, M, J . Chem. Phys., 22 1621 (1954). 9. Szwarc, M., L e a v l t t , F., Levy, M., and Stannett, V. 77 5493 (1955). 10. Szwarc, M., Rembaum, A. and Buckley, R. P. J . P o l . S c i . , XXIV 1621 (1957). 11. Szwarc, M. and Buckley, R. P. P r o c Royal. S o c , A, v o l . 240 396 (1957). 12. Szwarc, M., Buckley, R. P., Bader, and L e a v l t t , F., J . Amer. Chem. S o c , 79 5621 (1957). 13. Szwarc, M. and F e l d , M., J . Amer. Chem. S o c , 82 3791 (I960). -~ 14. Szwarc, M. and Matsuoka* i b i d . , 83 1260 ( 1 9 6 I ) . 15. Szwarc, M., Cresser, J . and Rajibenbach, A. i b i d . , 8J5 3005 (1961). 16. Szwarc, M. Herk, L. and S t e f a n i , A. i b i d . , 83 3008 (1961). — 17. James, D. G. L., and Stead»oe, E. W. R. P r o c Roy. S o c , A, v o l . 244 289 (1958). 18. James, D. G. L. and S t e a c i e , E. W. R. P r o c Roy. S o c , A, v o l . 244 297 (1958). 19. James, D. G. L. and MacOallum, D. P r o c Chem. S o c , J u l y 259 (I96I). 83 20. James. D. G. L. and Brown, A. 0. R. Ib i d . Feb. 81 (1962). 21. James, D. G. I>. and Brown, A. 0. R. Can. J. Chem. 40 796 (1962). 22. Dorfman, L. M. and Sheldon, Z . D. J . Chem, Phys., 17 511 (1949). 23. Kutsehke, K. 0., Wljnen, M. H. J. and Steacie, E. ¥. R. J. Amer. Ohem. S o c , 74 714 (1952). 24. Brinton, R. K, and Steacie, E. W. R. Can. J. Ohem., 33 1840 (1955). 25. Weir, D. S. J . Amer. Ohem. S o c , 8J. 2629 (1961). 26. Olson and Hudson. J. Amer. Ohem. S o c , 55 1413 (1933). 27. P I t z e r , K. S. and Hollenberg, J. L. i b i d . 76 1493 (1954). — 28. Craig, N. 0. and Entemann, E. A. i b i d . 83 304? (1961). 29. Ausloop, P. and Steacie, E. W. R. Can. J . Chem., 33 47 (1955), *~~ 30. Reddy, G. S,, Goldstein, J. H. and Mandell, L. J. Amer. Chem. S o c , 83 1300 (19.61).. 31. Brown, A. 0. R. His Ph.D. Thesis. (1962). 32. CTosfchwa,te,0\C. Mc Leskey.X} c*\<l Can. J . Ohem. 40 1879 (1962). -S^ith, p. 33. Q-ra^sie^ AJ . and M c N e i l l , l . C u j . p 0 l . S c i . 33 171 (1958). ^ • 34. Beevers, R. B. J. Phys. Ohem., 66 1271 (1962). 35. Dok. Akad. Uauk. S.S.S.R. v o l . 139 #3 605 (1961). 36. Wijnen, M. H. J . Ohem. Phys. 22 v o l . 6 1074 (1954). 37. Koch, J. K. J . Amer. Ohem. S o c , 84 1572 (1962). 38. Ays^cough, P. B. Trans. Far. S o c , 58 284 (1962). i3#« ...liewjL^ ,, 7?-.-. ifX, '• - 84 -39. L e w i s , F . M. and Mayo, F . R. J . Amer. Chem. S o c , 70 1533 (1948). 40 . L e w i s , F . M . , Mayo, F . R., W a l l i n g , 0 . , B r i g g s , E . R. and Gumming, W. J . Amer. Ghem. S o c , 70 1519 (1948). 4 1 . James. D. G. L . and MacOullum, D. unpubl i shed d a t a . 42. Shepp, A . and Kut schke , K . 0. J . Ghem. P h y s . , 26 1020 (1957) . ~ ~ 43 . Szwarc , M. and B i n k s , J . H . " T h e o r e t i c a l Organic C h e m i s t r y , " B u t t e r w o r t h ' s , London, 1959, p . 262. 44. A l f r e y , and P r i c e , 0 . C. J . P o l . S c i . V o l . I I .101 (1947). 45 . Schwan, and P r i c e , 0 . 0 . J . P o l . S c i . V o l . XL 457 (1959). 46. Bamford, 0 . H . , J e n k i n s , A . D. and Johns ton , R. Trans . F a r . Soc . 55. #3 418 (1959). 47 . A l f r e y , T . , M e r z , E . and Mark, H . J . P o l . S c i . 1 37 (1946). -48. Thompson, P r i v a t e communication. (1961). 49. S i v e r t z , 0 . J . P h y s . Ghem., 63, 34 (1959). 50 . L e w i s , F . M . , Mayo, F . R. and H u l s e , W. F. J . Amer. Chem. S o c , 67 1701 (1945) . 5 1 . L e w i s , F . M . , W a l l i n g , p.., Cummings, W . , B r i g g s , E . R. and Wenisch , W. J . J . Amer. Ghem. S o c , 70 1527 (1948) (a) ~ J . Amer. Ghem. S o c . , i b i d 70 1529 (1948) (b) 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.831.1-0061949/manifest

Comment

Related Items