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Some reactions of singlet delta oxygen Kubo, Masayoshi 1967

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SOME REACTIONS OF SINGLET DELTA OXYGEN by MASAYOSHI KUBO B.Eng., University of Osaka Prefecture, I 9 6 0 . A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF. MASTER OF SCIENCE i n the Department of Chemistry We accept t h i s thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA September, 1967• In p r e s e n t i n g 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 o f t he r e q u i r e m e n t s f o r an advanced d e g r e e . a t t he U n i v e r s i t y o f B r i t i s h C o l u m b i a , I ag r ee t h a t 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 r e f e r e n c e and S t u d y . I f u r t h e r ag r ee t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s may be g r a n t e d by the Head o f my Depar tment o r by h.iJ's r e p r e s e n t a t i v e s . It i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l no t be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Depar tment o f The U n i v e r s i t y o f B r i t i s h C o l u m b i a Vancouve r 8, Canada II ABSTRACT ' In Part I of t h i s work, the decay of Og^Ag) was studied at room temperature i n the flow system i n the absence of oxygen atoms. The decay of C ^ l ^ g ) was c l a s s i f i e d into f i r s t and second order decay with respect to ( ^ ( ^ g ) . The rate constant of the main f i r s t order decay with respect to C ^ l ^ g ) , which i s considered to be caused by c o l l i s i o n s .of C^^Ag) with wall of the reaction tube, was found to be 0.25 sec. The t o t a l second order decay constant was found to be 2.9 x 10^ 1/ mole sec. In Part II the reactions of excited oxygen molecules with some o l e f i n s vrere investigated. 2,3-Dimethyl-3-hydroperoxybutene-l was i d e n t i f i e d as the product of the . reaction.-of excited oxygen molecules with 2,3-dimethylbutene-2. 3-Methyl hydroperoxybutene-1 and 2-methyl-3hydro-peroxybutene-1 vrere produced by the reaction of excited oxygen molecule with 2-methylbutene-2. ... The decay of 0 2 ( 4 A g ) with 2,3-dimethylbutene-2 was also studied but the r e s u l t s could not be explained by any simple mechanism. III. CONTENTS Page Introduction 1 Experimental 12 1.) Material 12 2) Apparatus ]_3 3) Excited oxygen molecule measurement 4) Gas chromatography 19 5) Identification of products 23 Experimental results 24 ' 1) Decay of 02('Ag) without olefin 24 2) Analysis of products 30 i) Oxidat ion of 2;3-dimethylbutene-2--with excited oxygen molecules. 30 i i ) Oxidation of 2-methylbutene-2 with excited oxygen molecules. 31 i i i ) Oxidation of cis-butene-2 with excited oxygen molecules. 38" iv) Oxidation of iso-butene and propene with excited oxygen molecules. 38 3) Decay of 0 2 ( 'Ag) with 2,3-dimetliylbutene-2 47 Discussion 52 1) Decay of 0 2 ( 'Ag) . 5 2 2) Identification of products ' 5 9 i ) The reaction product of 2,3-dimethylbutene-2 with excited oxygen 59 I V . i i ) The reaction products of 2-methylbutene-2 with excited oxygen • 69 3) Decay of 0 2(^g) v/ith 2,3-dimethyl-butene-2 78 References 84 V. . LIST OF TABLES Page 1. Reactions of 0 2 ( 'Ag). 6 2. Oxidation products of olefin. 9 3. Optimum operating condition of gas chromatograph. 19 4. Decay of 0 2 ( 'Ag). 26 5. and kg 30 6. Decay of" 16340 with olefin. 47 7. Decay rate of I-634O at t= 0 . 51 3. Comparison of rate constants. 58 9. Comparison of NMR spectrograms. 60 10. Comparison of IR and NIR spectrograms. 6l 11. Comparison of NMR spectrograms. 74 VI. I j I S T j O g F I G U R E S . Page 1. Plow diagram of the system. 14 2. Diagram of d e t e c t o r c i r c u i t . 17 3. R e l a t i o n s h i p between HETP and f l o w r a t e of c a r r i e r gas.20 4. I n t e n s i t i e s of 6340A band as a f u n c t i o n of d i s t a n c e . 25 5. Gas chromatograms of the products of the r e a c t i o n s of s i n g l e t oxygen with, three o l e f i n s . 32 6. NIR spectrogram of the product from the r e a c t i o n of 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. 33 7. IR spectrogram of the product from the r e a c t i o n o f 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. 34 8. Mass spectrogram o f the product from the r e a c t i o n of 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. 35 9( a ) . HMR spectrogram of the product from the r e a c t i o n of 2,3-dimethylbutene-2 v/ith s i n g l e t oxygen. 36a 9 ( b ) . NMR spectrogram of the product from the r e a c t i o n of 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. ("C= 5) 36b 10. C a l i b r a t i o n curve of the product. 37 11(a). Gas chromatogram of f r a c t i o n (A.) from 2-methylbutene-2 r e a c t i o n . 39 11(b). Gas chromatogram o f f r a c t i o n (B) from 2-methylbutene-2 r e a c t i o n . 40 12(a). IR spectrogram of f r a c t i o n (A) from 2-methylbutene-2 r e a c t i o n . 41 12(b). IR spectrogram of f r a c t i o n (B) from 2-methylbutene-2; r e a c t i o n . 42 13(a). NMR spectrogram of f r a c t i o n (A) from 2-methylbutene-2 r e a c t i o n . 43 13(b). NMR spectrogram of f r a c t i o n (B) from 2-methylbutene-2 r e a c t i o n . 44 14(a). Mass spectrogram of f r a c t i o n (A) from 2-methylbutene-2 r e a c t i o n . 45 14(b). Mass spectrogram of f r a c t i o n (B) from 2-methylbutene-2 r e a c t i o n . 46 V I I . LIST OP FIGURES...continued Page 15. Mass spectrogram of 2,3-dimethyl-3-hydroperoxybutene-1 -taken by Winer and Bayes. 62 16. MR spectrogram of 3-methyl-3-hydroxybutene--1. 63 17. NMR s p l i t t i n g due to AB system. 65 18. HMR spectrogram of 3-methyl-3-hydroxybutene--1. 67 19. C a l c u l a t e d spectrogram of ABC system. 71 20. R e l a t i o n s h i p between log(-'U.) and log (R c ) . 80 21. R e l a t i o n s h i p between log(-V^ T p f e ) and log(I0). 80 22o R e l a t i o n s h i p between excess energy i n the stream and 23. R e l a t i o n s h i p between (At/AandA. 29b VIII. ACKNOWLEDGEMENTS To Dr. E. A. Ogryzlo (my Research Director) who suggested t h i s study and to whom I am indebted f o r his generous help and support; To Dr. D.P. Chong who generously gave of his time -to supervise my research during Dr. Ogryzlo's absence-and f o r c r i t i c i z i n g t h i s manuscript; To the many members of the techn i c a l s t a f f , and to Miss Barbara A. Albers f o r typing t h i s manuscript. J Introduction -Even though excited oxygen molecules were described :by Mulliken"^ as early as 1928 and had thereafter been observed In ...the upper atmosphere of the . earth^'^ in liqu i d ^ oxygen .and in e l e c t r i c a l l y discharged gaseous oxygen^>?'^>9, very l i t t l e was known about .the behaviour of excited oxygen -molecules u n t i l I960. Most of the early investigations were concerned with the recombination of oxygen atoms. This i s mainly because of the d i f f i c u l t y in getting excited oxygen molecules which are not mixed with oxygen atoms. -Some -properties and reactions of excited oxygen molecules already investigated are described below. 1). Species in the products of e l e c t r i c a l l y discharged oxygen. .By applying mass spectroscopy to e l e c t r i c a l l y -discharged oxygen, Poner and Hudson-^ and later - Herron and Schiff showed the presence of oxygen . atoms and a species with an appearance potential -0.93iO.leV below-that of ground state oxygen '(02( >Xg)). By a comparison of this energy separation with the spectroscopic separation of the 02(*Ag) and . -0 2(2£g), which i s .7882.39 cm"1(0.9772eV), they •suggested that i t might be 0 2(tAg), in which case --the concentration of 02(-*Ag) would be between 10 and 20%. E l i a s , Ogryzlo and S c h i f f ^ s t u d i e d e l e c t r i c a l l y discharged oxygen by means of an isothermal c a l o r i m e t r i c d e t e c t o r and t i t r a t i o n w i t h N O 2 , and found a discrepancy between the atom conc e n t r a t i o n s as determined by these methods. They confirmed t h a t ; i t was because of the presence of some other s p e c i e s , which d i d not r e a c t w i t h N O 2 , and whose c o n c e n t r a t i o n corresponded to about 10% of the t o t a l oxygen i f the species were 0 2('Ag). L a t e r , Bader and OgryzloA^ e s t a b l i s h e d the method to get r i d of oxygen atoms completely from the e l e c t r i c a l l y discharged oxygen by d i s t i l l i n g mercury through the discharge and c o a t i n g mercuric oxide j u s t a f t e r the discharge. This makes e l e c t r i c a l l y discharged oxygen s u i t a b l e f o r k i n e t i c and spectroscopic s t u d i e s . More r e c e n t l y Arnold"*"^ measured the c o n c e n t r a t i o n of the e x c i t e d species under the c o n d i t i o n s e s t a b l i s h e d by Bader and Ogryzlo and found about 6 or 8% of 0 2(*Ag) and 0 . 0 3 % of 0 2( !Xg) i n the oxygen' stream. From the f a c t s described above e l e c t r i c a l l y discharged oxygen contains approximately 10% oxygen atoms while another 10% i s e x c i t e d to the *Ag s t a t e . When mercury i s d i s t i l l e d through the discharge i n order to destroy the oxygen atoms, several percent 0 2 (*Ag) i s s t i l l present i n the oxygen stream and another species, ( ^ ( ^ g ) , i s also present i n very small amounts. V i s i b l e emission bands from 02(*Ag) The observation that a red-orange chemiluminescenee was produced during the reaction -of hydrogen peroxide and sodium hypochlorite i n aqueous solution was reported by Seliger-^. The reported wavelength of the red-orange chemilumine-scence was 634$A, but he made no attempt to i d e n t i f y the source of the emission. -l £ •Khan and Kasha measured the same red chemiluminescence which was composed of two emissions © 6334 and 7030A, under almost the. same conditions. Arnold ,Ogryzlo and Whitzke^? investigated the e l e c t r i c a l l y ' d i s c h a r g e d oxygen flow spectroscop-i-cally and also observed emissions at 6340 and 7030A. When oxygen atoms were removed by the d i s t i l l a t i o n of mercury through the discharge, the .two .peaks, remained unaltered while the 7600. and. 8600A peaks, which are (0,0) and (0,1) t r a n s i t i o n s i n the '51 g —> 3X g system, were only s l i g h t l y lowered. 4. The possibility that impurities (water and N O 2 ) could give rise to emission in this region were -eliminated by the measurements of intensities of these emissions with specially dried and nitrogen-free oxygen and by addition of water and N O 2 , before and after the discharge. The two emissions were essentially unaltered by these changes. -More evidence that the 634OA radiation i s due to C>2('A.g), was found by Bader and 0gryzlol3. They showed that the intensity of the 6340A emission was proportional to the square of the concentration of 02('Ag) measured by an isothermal calorimetric detector. On the other hand, March, Furnival and Schiff-^ monitored the concentration of 02('Ag) by i t s emission at 12700A and found that the emitted intensity at 6340A was proportional to the f i r s t power of the 02('Ag) concentration. Later, whitlow and Findlay-^-9 investigated the relationship between' the intensity of 6 3 4 0 ! ( 7 0 3 0 A ) and that of 12,700A* -by-using an RCA Victor PD523 detector to measure o the-intensity of 12,700A, and concluded that the © -intensity of o340A emission was proportional to the square of the intensity of 12,700A. Arnold and Ogryzlo also showed, that the .intensities of both "634O and 7030A emissions were proportional to the square of the co n c e n t r a t i o n of 0 2( 'Ag) measured ' by an isot h e r m a l c a l o r i m e t r i c d e t e c t o r . F a l i c k and Mahan 2 1 detected 0 2( 'Ag) by EPR spectroscopy, which has the advantages of s p e c i f i c i t y and s e n s i t i v i t y , and obtained the r e s u l t that the i n t e n s i t y of 6 3 4 0 A " was p r o p o r t i o n a l to the square of.the c o n c e n t r a t i o n of 0 2 ( 'Ag) . I t i s q u i t e d i f f i c u l t to detect 0 2('Ag) q u a n t i t a t i v e l y by i t s emission at 12,700A using a p h o t o m u l t i p l i e r because of low s e n s i t i v i t y of p h o t o m u l t i p l i e r s i n t h i s s p e c t r a l r e g i o n . On the other hand, though the isothermal c a l o r i m e t r i c technique has the re q u i r e d s e n s i t i v i t y , i t has been c r i t i c i z e d f o r i t s unknown thermal e f f i c i e n c y and l a c k of 2 1 s p e c i f i c i t y . However i t should be noted that -the c o n c e n t r a t i o n of 0 2('2Ig) was shown by Arnold to • be n e g l i g i b l e compared to 0 2 (Ag ) i n discharged oxygen with oxygen atoms removed by-mercury. Since the quadratic r e l a t i o n .between 0 2 ( l Ag) and i n t e n s i t y of emission at o340A i s reasonably w e l l e s t a b l i s h e d the i n t e n s i t y of emission at 6340A provides a convenient way of es t i m a t i n g 02(*Ag) c o n c e n t r a t i o n . 3 i . ) Reactions of 0 2( 'Ag) i n Pure Oxygen Systems. Reactions of 0 2 ( 'Ag) have been stud i e d by • s e v e r a l i n v e s t i g a t o r s - ^ > 21?22,23-, 24 > 25. Their r e s u l t s are summarized i n Table 1. 6 . TABLE 1. Reactions of 0 2 ( ' A g ) . No. Reaction Rate Constant Ref. 1. 0 2 ( ^ g ) -> 02(3Zg-)+h*>(l2680A) 1 .5 x lO-A-sec" 1 22 2. 02('Ag) — » 0 2( 3Xg") 0.178 s e c - 1 14 3.. 0 2 ( , Ag)+0 2(3£g) —> 20 2 ( 3 * g ) ^ 2.77xl0 2Xmole t secl8 ^1.53x10 " 23 4. 20 2( ,A.g) 20 2 (3xg~) or [o 2( 3^g-)3- 2-rhP(6340 and 7030A) 0 . 2 8 J U o l e sec 24 (3*0.6)xl0~2 n 21 5. 20 2 ( , A g ) —-» 0 2 ( / Z g)-0 2 ( i X g - ) 1.3x103 14 1.8x107*0 0 " 25 6 . 20 2 ( 'Ag) — > p roduc ts ? ^ 4.3xl0 2 " 14 A l l of these reactions except the f i r s t vrere investigated in e l e c t r i c a l l y discharged systems. i i ) Reaction of 0 2( 'Ag) with organic compounds. While.there are many papers 2D,27,28,29 o n photosen-stized autoxidation and hydrogen peroxide oxidation -of organic compounds, few papers^ 3 J 30> 3^ have been ..published about the reaction of singlet oxygen . molecules with organic compounds in the gas phase. 0^ First Corey and Taylor^ used discharged oxygen flow to oxidize organic compounds in the liqu i d phase. They oxidized anthracene, 9>10 — diphenylanthracene and 9;10-dimethylanthracene with 7. the dir e c t products of discharged oxygen, and converted them to the corresponding 9,10 — endoperoxides. They concluded that the oxygen which reacted with anthracene and i t s derivatives was 0 2 ( A g ) or 02('.2Lg) because: 1) Gaseous oxygen, which was not discharged, did not react with them and i t also seemed improbable that v i b r a t i o n a l l y excited 0 2( 32Tg) could p e r s i s t long enough to ef f e c t oxidation i n solution. 2) Ozone and atomic oxygen would lead to other 32 types of products^ . They also attempted to convert o l e f i n s to a l l y l i c hydroperoxides but they did not succeed i n the cases of -pinene, I - p h e n y l c y d o K e x e n e ,, t e t -r a m e t h y l e t h y l e r v e and cholest-4-en-3^ - o l . 31 F a l i c k , Mahan and Myers^ noted a possible reaction of 0 2('Ag) with ethylene i n the homogeneous gas phase because of the reduction of the EPR.signal from 0 2('^g) by addition of ethylene but they did not.attempt to get reaction products. Even though Corey and Taylor could not succeed i n getting a product from the oxidation of tetramethylethylene by 0 2('Ag) or 0 2 ( 'ZIg), Winer and Bayes 3 got a product i n the homogeneous gas phase •reaction of tetramethylethylene with (^('Ag).. The product was i d e n t i f i e d as 2p —dimethyl-3-hydroxybut-ene—1. It should be noted that they put a small amount of water into the system a f t e r the discharge -•which was enough to destroy any G^ClEIg) which might be produced by the reaction. 20 2('A g) -> 02{l£g)+02CZ-g) As i s already known, si n g l e t oxygen molecules are produced by the reaction of hydrogen peroxide with sodium hypochlorite or a halogen 3 3 and several papers have been published on the oxidation of organic compounds with t h i s s i n g l e t oxygen. It i s i n t e r e s t i n g to compare the products of organic compound oxidations by oxygen gas with photosensitizer and l i g h t , r e a c t i o n of hydrogen peroxide with sodium hypochlorite or halogen, and discharged oxygen gas. These comparisons are shown i n Table 2. In the oxidations involving an e l e c t r i c a l discharge there i s no question that G^f'Ag) i s the active reagent. Since (^('Ag) has been observed to .be present in.the -H2O2 systems and the products -9. are the same i t seems reasonable to assume that O^C'Ag) is the active reagent in this system too. Furthermore because the photochemical oxidations of these systems produces identical products in the same ratio i t has been p r o p o s e d 3 ^ t h a t singlet :oxygen i s also involved in these systems. TABLE 2. Oxidation of Olefins. Ratio of the products Photosensi- oxid.with tized auto- H202_ discharged xidation ^2 Reactant Product 26,27,28 26,27,28,29 23,30 \ y, <K / a) /*=\ / ~ ^ O H 1 0 0 1 0 0 1 0 ° B ) Ton aj" 52 51 48 49 X. a; 49 51 Y~Y_ 51 49 ^ - < ^ ^ 96 94 W • , > — > - > 6 A ^ p o H 2) 100 ? :0H 49 48 * W~ 31 34 ;*H 11 9 10. Ho.. 21 IB Ho, 10 3 7 25 24 ^/(yAd> - 4 A fa 100 100 100 d) 100 100 100 d) 30% e ) 100 e) 100 f ) 100f) a) Products were reduced by t r i m e t h y l phosphite or sodium borohydride (MaBH^) b) The product was found as a hydroperoxide i n s t e a d of hydroxide c) ~ Methanol was used as a s o l v e n t . d) Other products were unknown. e) B r 2 was used i n s t e a d of sodium h y p o c h l o r i t e . f ) ^ Discharged oxygen molecules Were bubbled i n t o the s o l u t i o n c o n t a i n i n g r e a c t a n t . 11. Present work. \ The present work involves 1) homogeneous gas phase reaction of s i n g l e t oxygen -molecules [ " ( ^ ( ' A g j J ' i n the absence of any added reagent. 2) i d e n t i f i c a t i o n of products by the reaction of sing l e t oxygen molecules with 2,3— dimethylbutene -2 and with 2— methylbutene-2. 3) k i n e t i c study of decay of s i n g l e t oxygen molecules with 2,3-dimethylbutene-2. 12 Experimental 1) Materials i) Oxygen Matheson Company oxygen (extra dry grade), found to contain much less nitrogen than oxygen obtained from Canadian Liquid Air, was used as a source of excited oxygen molecules without any purifica-tion. .ii) 2,3- Dimethylbutene-2 2,3- Dimethylbutene-2 from K and K Inc. Ltd. was found by gas chromatography to contain at least five impurities, among which were water and 2,3-dimethyl butaTio(-2. The crude 2,3-dimethylbute ne -2 was purified with a spinning band column d i s t i l l a t o r which had more than 20 theoretical plates. The d i s t i l l a t e , more than 98% pure by chromatogram area, was used for the experiments. I i i ) 2-Methylbutene-2 Research grade 2-methylbute.ne-Z (Phillips Petroleum Co.; mani/f acturers specif ication: 99.7 mole %) was used without further purification. iv) cis — Butene—2 Research grade cis-butene-2 (Phillips Petroleum Co, manufactures specification: 99*91 mole %) was used without further purification. i s o — B u t e n e R e s e a r c h g r a d e i s o - b u t e n e ( P h i l l i p s P e t r o l e u m C o . ) w a s u s e d w i t h o u t f u r t h e r p u r i f i c a t i o n . P r o p y l e n e R e s e a r c h g r a d e p r o p y l e n e ( P h i l l i p s P e t r o l e u m C o . ; m a n u f a c t u r e s s p e c i f i c a t i o n : 99*99 m o l e %) w a s u s e d - w i t h o u t f u r t h e r p u r i f i c a t i o n . A p p a r a t u s A s c h e m a t i c d i a g r a m o f t h e f l o w r e a c t i o n . s y s t e m , i s s h o w n i n F i g . I . T h e p y r e x r e a c t i o n t u b e h a d a n i n t e r n a l d i a m e t e r o f 2 . 5 cm a n d a l e n g t h o f a b o u t 120 cm a n d w a s n o t j a c k e t e d . T h e o x y g e n g a s w a s d i s c h a r g e d i n a p y r e x t u b e o f a b o u t 10 cm i n l e n g t h a n d 1.0 cm i n i n t e r n a l d i a m e t e r a b o v e t h e r e a c t i o n t u b e . I n t h e c a s e o f r e a c t i o n s o f 0 2 ( l A g ) w i t h o l e f i n s , t h e o l e f i n g a s w a s i n t r o d u c e d i n t o t h e r e a c t i o n t u b e t h r o u g h a n i n l e t j e t w h i c h e x t e n d e d i n t o t h e r e a c t i o n t u b e . T h e r e a c t i o n p r o d u c t s w e r e c o l l e c t e d i n a c o n v e n t i o n a l c o l d t r a p w h i c h w a s k e p t a t a p r o p e r t e m p e r a t u r e (-196°C o r -70 o G) ' . A R a y t h e o n G e n e r a t o r N o . KV-IO4SB ' w h i c h w a s u s e d t o o b t a i n a n e l e c t r o d e l e s s CYLINDER cb AfR ro McL EOO G A U 3 £ 1_ rOi . ? -e-0 DISCHARGE. TO Mc.LS.OQ RELACTfON TUP.£ 0. 1 PHOTO MULT I PLItLff TO PUtAP 0 ro PUMP Figure I: Flew diagram of the system discharge, generates a continuous 2450. megacycle wave with a maximum power output of 125 Watts. When the output i s directed at a stream of oxygen through a d i r e c t o r , a discharge may be i n i t i a t e d under the proper conditions of pressure,flow and tube size by the ap p l i c a t i o n of a spark from a Tesla c o i l . The flow rates of oxygen and o l e f i n gases were controlled and measured by i d e n t i c a l systems. The flow rates were varied by Edward f i n e - c o n t r o l needle valves. The pressure difference established across a c a p i l l a r y was measured by a U-tube manometer f i l l e d with mercury i n the case of oxygen and with O c t o i l i n the.case of o l e f i n vapor. The flow rate of oxygen was determined by c o l l e c t i n g the gas and by a soap f i l m flow-meter at the exit of the mechanical pump when the steady state conditions had been established. The flow rate of 2,3-dimethylbutene-Z was determined by c o l l e c t i n g the gas i n a l i q u i d nitrogen trap, tran s f e r i n g i t to a weighing bottle and weighing i t . The absolute pressure i n the reaction tube was measured with t i l t i n g McLeod gauges with a range of 0.1 to 5rs\m Hg, located at either end of the reaction tube. There was at most 1.5% pressure •drop i n the reaction tube.. 16. Excited oxygen molecule measurement. The excited oxygen molecules flowing i n the reaction tube were measured by an isothermal calorimetric -detector developed by Ogryzlo. This detector consisted of a h e l i c a l l y wound s p i r a l of platinum.; j wire electroplated with cobalt, which could be f i x e d i n the reaction tube. The platinum wire coated with cobalt formed one resistance arm of the Wheatstone bridge c i r c u i t shown i n F i g . 2. -With the discharge off,, that i s , no excited oxygen molecules flowing., current was passed •through the detector, and the bridge was balanced by adjusting the current and/or the resistance of the decade resistance box. The current through the detector was then measured oh an accurate potentiometer by measuring the p o t e n t i a l drop across the 1 ohm p r e c i s i o n r e s i s t o r . . With the microwave discharge on and •excited oxygen molecules present„ the excited molecules were deactivated on the <-'0/Pt c o i l r e l e a s i n g 23 Kcal/mole (deactivation energy of OgC'Ag) to ground state) i n the ftorm of heat. For -the bridge to be -balanced under tlhese conditions, -the current through the detector Ihad to be decreased, returning the c o i l to i t s o r i g i n a l P P"OT£. N TIO •/? C7*£ R G C A i V A NO MET B R •7 TAP PI <V a K £ Y. F i g u i v 2: Diagram of detector c i r c u i t . IB. temperature and thus i t s original resistance. From' the magnitude of decrease in the squares of the currents A ( i ^ ) , the excited molecule flow incident on the detector could be calculated by the following formula, i f the e x c i t a t i o n energy of the excited oxygen molecules i s known. 0 ?(excited) flow = A (i 2)R moles/ 4-18E sec where A ( i 2 ) i s the current squared decrease, i.e. •A (±2) = ±±2 - i | R i s the resistance of the detector and E i s the average excitation energy of excited oxygen molecules. Since i t i s known that more than 99% of the excited state oxygen molecules are 02('Ag) under these particular experimental conditions, E can be taken as 23 KCA\/mole which i s the excitation energy of 02('Ag) from the ground state. Once i t had -been established that the intensity of the 6340A band was. proportional to the square of the 02(2Vg) concentration, changes in the 02(^\g) concentration as a function of time, position or added gases could be easily and rapidly determined by measuring changes in the intensity of 6340A band with an RCA 7265 photomultiplier which was mounted on an optical bench parallel to the reaction tube. Gas chromatography An Aerograph gas chromatograph Model A 90 P-3 (Wilkins Instruments & Research Inc.) was used for detection and separation of reaction products. To find the optimum operating conditions of the gas chromatograph, the relationship between the height equivalent theoretical plate (HETP) and flow rate at different column temperatures .was investigated. These relationships are shown in Fig. 3. The st a b i l i t y of the product of the reaction between 2,3-dimethylbutene -2 , and (^('Ag) depends on column temperature. For example at a column temperature of 80°C, a new peak in trace amounts was detected with a retention time between those of reactant and product. Therefore, a 60°C column temperature was used. The operating' condition of the gas chromatograph i s shown in the Table 3. . TABLE 3. optimum operating conditions of gas chromatograph. column temperature : 62°C detector temperature •: 77°C carrier gas : He 60 ral/min column ' : SE -30, "5 f t . detector current : 150 mA (SE-30: S i l i c o n e gum rubber) *I0 Ir^cL rz.o 5: /o.o O 20 40 GO 80 /oo . 12.0 Plow r a t e of c a r r i e r gas Figur e C3(b5:: R e l a t i o n s h i p ibetween IIETP,.and . . f l o w r a t e . o f c a r r i e r gas. . '•.:'••"••:/'•'•. (column temperature: 62°c) -20 40 60 So /oo /xo /to Flow rate of c a r r i e r gas 7/'^4.-//L. Figure 3 ( c ) : (Relationship: between H E T F and - flow rate, of c a r r i e r gas. .. • ••' (column temperature: . 45°C) ' 23. Quantitative analysis of the oxidation product : of 2 ?3 - d«7nethyl b u f c e n e - 2 by gas chromatography under the optimum conditions was also investigated. The peak area of reactant and product was c a l i b r a t e d by NMR spectroscopy. I d e n t i f i c a t i o n of Products. I d e n t i f i c a t i o n of oxidation products was made by taking IR, NMR and mass spectrograms a f t e r each product was separated by trap-to-trap d i s t i l l a t i o n i n the vacuum system and/or by gas chromatography. The following spectrometers were used. , . . -I.R.: Model 21 Double Beam IR Spectrophotometer (Perkin-Elmer Corp.). NMR : A-60 Analytical•NMR Spectrometer (Varian Associates) JEOL - high resolution NMR instrument (Japan Electron Optics Lab. Co. Ltd..) Mass Spectrometer: Model M.S.9 (Associated E l e c t r i c a l Industries Ltd.). 24. Experimental results 1) Decay of 0 2( yAg) without olefin. The intensity of emission at o340A was measured as a function of distance (a) along the reaction tube.. A typical plot of this kind i s shown in Fig. 4-A series of -such measurements were taken at a. constant flow rate of oxygen and various powers of. the discharge. As can be seen in Fig. 4« the decay of the concentration of 02('Ag) i s very small. The square root of the intensity along the reaction tube i s almost a perfect straight line over the distance measured, with a coefficient of correlation of more than 0.98. Therefore, the slope of line was taken as the rate of decay at the middle of the measured "distance. The flow rate of 02('Ag) was determined by the formula 02(lAg) = a f i .6340 where jo i s the intensity of emission at 6340A -6340 and a i s a constant obtained by isothermal calorimetric calibration. The results are shown in Table 4-. - 0 io 2.0 3o 4-o so 6o 70 So 9o C r n Df STANCE ALONG OBSERVATION TUBE Figure 4: I n t e n s i t i e s o f 6.340 A band. as a function of distance. •. TABLE 4(a) Decay of 0 2('Ag) - d / T / d z . Jl 0 2('Ag) -dA/dt/A arb. unit/em x 10^ ar b i t r a r y Unit, /a mole/sec ., sec"1 0.617 4.93 10.8 0.449 0.596 4-76 10.4 0.449 0.500 4.12 8.98 0.436,-0.378 3.51 7.65 O.388 Total flow rate of oxygen 180 u mole/s-ec Pressure 2.08 rnmHg linear velocity 359 cm/sec TABLE 4(b) Decay of 0 2('Ag) 0.625 4.85 10.6 0.495 0.675 4.87 10.6 O.5O6 O.563 4.28 9.33 0.480 0.501 3.95 8.61 0.462 0.413 3.27 7.13 0.459 Total flow rate of oxygen "200 p. mole/sec Pressure 2.03 rnmHg linear velocity 364 cm/sec TABLE 4 (c) Decay of 0 2('Ag) O.55O 4.20 9.16 0.495 0.995 6.55 14.3 0.575 0.910 6.23 . 13.6 0.552 0.715 5.24 11.4 O.5I4 Total flow rate of oxygen 380 u mole/sec Pressure 3.78 rnmHg. linear velocity 378 cm/sec. TABLE 4(d) Decay of 0 2( 'Ag) -dyr/dz. yr o 2 ( ' A G ) arb. unit/cm x 10^ a r b i t r a r y Unit u mole/sec 0.660 0.570 0.400 0.795 0.725 4.94 4-49 3.45 5.67 5.43 Total flow rate the oxygen Pressure l i n e a r v e l o c i t y 10.8 9.79 7.52 12.4 11.8 -dVdt / A ' sec 0.501 0.475 0.434 0.524 0.501 275 p mole/sec 2.77 mmHg 374 cm/sec TABLE 4(e) Decay of 0 2('Ag) 0.455 0.475 0.400 0.375 0.275 4.20 4.29 3.86 3.61 2.95 11.1 11.4 10.2 9-57 7.82 0.391 0.402 0.376 0.376 0.340 Total flow rate the oxygen Pressure l i n e a r v e l o c i t y 183 ju mole/sec 1.90 mmHg 362 cm/sec TABLE 4(f) Decay of 0?('Ag) 0.430 O.638 O.588 0.530 4-05 5.06 4.90 4.57 10.7 13.4 13.0 12.1 0.394 O.443 0.446 0.432 Total flow rate the oxygen Pressure l i n e a r v e l o c i t y 277 P mole/sec 2.80 mmHg 372 cm/sec TABLE 4(g) Decay of 0 2('Ag) - d J T / d z . TT 0 2 ( ' A s l a r b . unit/cm x 10^ a r b i t r a r y Unit JJL mole/sec -dA/dt/ A 0.775 0.405 O.485 0.725 5.67 3.56 4.35 5.65 Total flow rate of oxygen Pressure l i n e a r v e l o c i t y 15.0 9.43 11.5 15.0 'sec"1 0.518 0.431 0.420 O.48 •4-443 p mole/sec 4.40 mmHg 378 cm/sec TABLE 4(h) Decay of 0 2('&g) 0.520 0.625. O.58O 0.415 4.64 5.29 5.04 3.92 12.3 14.0 13.4 10.4 0.419 0.441 0.430 0.393 Total flow rate of oxygen Pressure l i n e a r v e l o c i t y 318 u mole/sec 3.20 rnmHg 374 cm/sec 29. On the assumption that the decay of 02(lAg) i s a sum of two terms, f i r s t order and second order with respect to 02('Ag), the rate equation for the decay can be expressed as . - f t . - k A * t k B t f ( 1 ) where and kg are total rate constants of f i r s t order and second order decays respectively and A i s the concentration of 02('Ag). Dividing both sides" by A , one gets d£ (2) A plot of -^fV against A showed a straight line dt/A whose intercept and slope are total f i r s t order and second order rate constants respectively. The calculated k^ and kg by this analysis are shown in Table 5- The p l o t of-^/A a g a i n s t A i s a l s o shown i n Figure 23. 30. TABLE 5 k A and kg , Total flow . . k.' . • kg x 10 - Z f rate of oxygen ." sec1. L/rnole sec. mole/sec. 180 0.273 3-05 200 0.351 2.54 380 0.350 2.82 275 0.304 3.39 183 0.216 2.84 277 0.189 3.56 443 0.277 2.73 318 0.259 2.39 av. 2.92 2) Analysis of products i) Oxidation of 2,3-dimethylbute"ne-2 with excited oxygen molecules Oxidation products of 2,3-dimethyl butene-2 with non-discharged and discharged oxygen were investigated. In the former case, that i s , the oxidation of the olefin with ground state oxygen molecules, no product was found except trace amounts of water which may have come from the oxygen from the cylinder. With the discharge on, only one product was found by gas.i chromato-graphy. The product has a f a i r l y high boiling point and was separated from reactant by trap-to-trap d i s t i l l a t i o n in the vacuum system. In addition to peak (a) due to the unreacted material and 31 peak (b) due to the product two small peaks can be seen. These were found to be due to impurities i n the reactant which were concentrated i n the trapping a n d _ d i s t i l l a t i o n process. (Figure 5(a)). Infra-red, MIR, mass and NMR spectro grams of t h i s p u r i f i e d product were taken to Identify the product. These spectrograms'-are shown i n Fig.6,7,8 ,9 . Quantitative analysis by gas chromatography was also u n d e r c a k ^ i . The c a l i b r a t i o n curve of the reaction mixture i s shown i n F i g . 10. The r e l a t i v e concentration by NMR was found by comparing the intergrated area of some p a r t i c u l a r protons belonging to the reactant and the product. Oxidation of 2-methyl butene-2 with excited oxygen molecules. One of the t y p i c a l gas .chromatograms of the reaction mixture i s shown i n Fig. 5(b). It was taken under the same conditions of gas chromatography as was used to detect the product of 2j3-dimethylbuterte — 2 oxidation. The gas chromatogram; shows two main products and two other minor products whose r e l a t i v e area to those of main products increased with time. From t h i s point of view, those' two minor products are secondary products which may be polymers of main product. After the two . 4 10 ts M r MUT£ S (a) 2,3-Dimethylbutene-2.-20 A e 10 ts /VJ//VUT£ S (b) '2-Methylbutene-2." I" S O 2 0 Figure 5: Gas chromatograms of the products of the r e a c t i o n s of s i n g l e t oxygen w i t h three o l e f i n s . 1 2 0 0 1 0 0 0 9 0 0 . 8 0 0 - 7 0 0 IR spectrogram o f the product from the r e a c t i o n . o f 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. TO i i i J2.0 3>0 J J J L L — L i _ I I i 4-0 60 70 80 /oo //o 12.0 Figure 8: Mass spectrogram of the product from the r e a c t i o n of 2,3-dimethyl"butene-2 with, s i n g l e t oxygen. 5 & > ' ' i - l I r 1 _ 1 1 ! i 1 1 | ' , • 1 1 1 1 ' " l i'" i 1 r i' t 1 t I , i . 1 J 1 I I . . 1 1 1 1—I 1 • • i ' . . . . ! . i ' ' " 1 1 1 1 1 I i • Figure 9b: HMR .spectrogram of the product from the ' r e a c t i o n of 2,3-dimethylbutene-2 w i t h s i n g l e t oxygen. _. 5 j ! PRODUCT HoLB FRACTION (NMR) Figure 10: ' C a l i b r a t i o n curve of the product. (Product: • 2,3-dimethyl-3-hydro- ' peroxybutene-1 ) 3&\ main products were separated by gas chromato-graphy, attempts were made to i d e n t i f y them by .IR, NMR and niass spectrometry. It was found that i t i s easier to separate the one with the shorter retention time from the other but " t a i l i n g " of the f i r s t product peak made c o l l e c t i o n of the .second quite d i f f i c u l t under .the gas chromato-graphic conditions used. Thus, f o r the- i d e n t i -f i c a t i o n of the second main product, the f r a c t i o n (B) containing both main products. wras used. Gas chromatograms, IR, NMR and miass spectrograms of these separated f r a c t i o n s .are shown i n Fig . 11, 12, 13, 14. Oxidation of cis-butene-2 The gas chromatograrn. of the reaction .mixture i s shown i n Fig . 5(c) • A very small amount of product and a trace of water trapped by l i q u i d nitrogen were found, but no further i n v e s t i g a t i o n of t h i s product.was made. -Oxidation of iso-butene and propene with excited oxygen molecules. Nothing detectable by gas chromatography was trapped by l i q u i d nitrogen except the reactants and a trace of water,.' , -itvrrj-jt.v xi.ivn .'.u vovn.^.ut javii-.' • :os jointlyM» I .» '-owT w.oj, j r i i iuVHJ'uuv utvii vuviiyj tn.juvn ... 'oa wn«iHiu( —-f,— , • - - - - - - — — - — -, ' . .. — ' _ — " — : ' — — ; — ' • — — . — _ r ..' ~ . — — : • -— - — -' — „ . _ _ •; ... 1... _ . . . . - — — — — — — ~ — : — - - — - — — r -. — - — — — - - - - - — • - : '- -•: - -. . . . . — . — -•— ••• • _ - - - — — • • — - — - - — ' • - . _ . i • _ — - : — - — - - — — — . ' . . -- ; — - _:1 — -•• . . : • — • • - .. f . T . V ! • — U . . • -- — •' — , - - — . _ -- - : -•• > — - ' - i \ • — — ' \ . — • — — — - — f — » y ' '"1 U——- : 1. * • • — - * r i t • ~ — ...J ._. — ~ l ] 1 / — L. —-7-Y— _ -— : — • : / :  .: 1—y ~" ^ . 1—. _ \ - — — — •— _ — \ -_ — ~—-- — ., '•-— _ . — . 900C09 'CH : — ' • 900009 "°N —— • : — ' • 900009 '°H F i g u r e 11 ( a ) : Gas chromatogram of f r a c t i o n (A) from 2-methylbutene~2 r e a c t i o n . F i g u r e 13 ( a ) : BMR spectrogram of f r a c t i o n (A) from 2-methyl"butene-2' r e a c t i o n . 2- jmetliyl'butene-2 r e a c t i o n . 2.0 30 4 0 so'- 60 70 — i — 80 ?0 Figure_!14 ( a ) : Mass spectrogram of f r a c t i o n (A) from 2-methylbutene-2 r e a c t i o n * 14 30 4-0 ~\— GO LLJLJ 70 SO to F i g u r e 14 ( b ) : Mass spectrogram of f r a c t i o n • (B) from 2-methylbutene-2 r e a c t i o n . 47. 3) Decay of 0 2 ('Ag) with 2,3-dimethylbutene-2 The intensities of emission at 6340A as a function of distance from olefin inlet tube are tabulated in the tables under constant flow rate of total oxygen and different flow rates of ( 32('Ag) and olefin. (Table 6) TABLE 6 (a ) Decay o f I6340 with olefin at different pi distance Power of discharge from inlet ' 70% 50% 30% 20% 10% tube. cm 2 27.2 25-4 22.2 19.1 12.1 5 26.7 24.8 21.4 18.3 11.2 10 25.8 24.1 20.5 17.3 10.2 15 25.2 23.2 19-7 16.4 9.2 20 24.4 22.3 19.0 15.5 8.5 30 23.6 21.3 17.8 14.6 7.3 40 22.2 20.2 16.7 13.5 6.5 50 21.4 19.3 15.7 12.8 5-7 60 20.5 18.6 15.2 12.1 5.2 70 20.0 17.9 14-5 11.6 4.8 80 19.1 17.2 13-9 11.0 4*4 90 18.4 16.4 . 13.4 10.5 4.2 A 2 = -(2.18)2 16340 flow rate of olefin : 0.14 mole/sec total flow rate of oxygen: 180 :|A mole/sec TABLE 6 (b) Decay of I5340.with olefin at different powers. distance Power of discharge from inlet 70% 50% 30% 19% * 10% tube. cm 2 26.4 24-9 21.4 18.0 11.3 5 25.7 24.2 20.5 17.0 10.5 10 24.7 23.2 19.6 15.9 9.2 15 24.1 22.4 18.6 15.0 8.4 20 23.0 21.7 17.9 13.9 7.2 30 22.0 20.4 16.5 12.6 6.3 40 20.6 19.4 15.4 11.3 5.2 50 19.7 18.2 14.5 10.8 4.7 60 18.9 17.6 13.9 10.1 4.1 70 18.2 16.8 13.2 9.6 3.8 80 17.3 16.1 12.7 9.0 3.4 90 16.6 15.4 12.2 8.4 3.2 flow rate of olefin; 0.41 mole/ TABLE 6 (c) Decay of X6340 with olefin at different powers 70% 50% 30% 20% 10% 5 1.0 20 30 40 50 60 70 80 90 25.1 23.9 21.7 19.9 18.3 17.2 16.3 15.4 14.8 14.0 23.5 22.2 20.1 18.2 16.8 15.5 14.8 13.8 13.1 12.5 20.4 18.9 16.7 14.9 13.5 " 12.3 11.7 10.9 10.3 9.9 16.4 14.9 12.4 10.8 9-4 8.6 7.9 7.2 6.9 6.4 11.4 9.9 7.4 6.2 4.8 4.2 3.4 3.1 2.8 2.5 flow rate of olefin: 0.82 ./A mole/sec 49. TABLE 6 (d) distance from i n l e t tube Decay of I^-^O v / i t h o l e f i n at d i f f e r e n t powers. 70% 50% Power of discharge 30% 20% 20% 10$ p cm. 2 25-7 23.6 20.6 17.5 16.7 10.0 5 24-3 22.2 19.2 16.1 15.2 8.8 10 22.6 20.6 17.5 14-5 13.5 7-1 20 19.9 17-8 14.7 12.0 10.9 4.6 30 18.0 15-9 13.0 10.0 9.0 3.0 40 16.2 14-2 11.4 8.8 7.8 2.1 50 15.0 13.0 10.3 7-7 6.7 1.5 60 14.0 12.2 9.4 7.0 6.0 •1.1 70 13.2 11.4 8.7 6.3 5-4 0.8 80 12.2 10.6 8.0 5-9 4-9 0.7 90 11.6 10.0 7-5 5-4 4 • 4 0.5 flow rate of o l e f i n 1.10 jJ- mole/ sec. TABLE 6 (e) distance Flow rate of o l e f i n JUL mole from i n l e t 1.79 1.54 1.07 0.72 tube 2 cm 16.7 17.1 17.1 17.4 5 15.0 15-5 15-6 16.0 10 12.5 13.3 13-6 14.2 20 9.0 10.2 -• 10.9 11.6 30 7.2 8.3 9.0 10.1 40 5-5 6.9 7-5 8.8 50 4.8 5.8 6.6 8.1 60 4.0 5.1 5-9 7.2 70 3.5 4.5 • 5-4 6.9 80 3.0 4.0 4-9 6.2 9.0 2.6 '3.6 4.4 5-9 at d i f f e r e n t low rates 0.34 17.5 16.3 15.0 13.0 11.6 10.7 9.8 .9.2 8.7 8.2 7.8 TABLE 6 (f) Decay of I5340 a t different low rates of olefin, distance Flow rate of olefin kA. mo le/sec. from inlet 2.00 1.33 0.82 0.76 0.24 tube 5 cm 23.3 24-7 25.1 25.7 26.0 10 21.6 23.0 23.9 24-5 25.0 20 18.4 20.1 21.7 21.9 23.2 30 15.9 17.9 19.9 20.1 21.8 40 13.8 16.0 18.3 18.4 20.4 50 12.1 14.6 17.2 17.0 19.4 60 10.9 13.6 16.3 16.2 18.6 70 9.8 12.5 15.4 15.2 17.8 80 8.8 11.7 14.8 14.5 17.1 90 8.0 11.0 14.0 13.9 16.6 The attempt to find the rate equation was made assuming a simple decay mechanism. For this purpose, i t i s quite convenient to find an inital-rate under certain conditions. The plot of log (- 6/4z) against-distance (z) showed a f a i r l y good straight line especially at high flow rate of olefin. Therefore, the i n i t i a l rates (Vo) were determined as intercepts o-f these lines. The real i n i t i a l rates (vo) of decay of 02('Ag) with the effect of olefin were determined by subtracting the rates (U0) of decay of O^t'Ag) i t s e l f from the rates (Vo) determined by tke above method. The summarized results are shown in Table 7. TABLE 7 Decay rate of 15340 a t t=o. Ro Vo Uo YD s e t Io . >mole ' . I434O'' I634C, *6340 sec .— —-10 cm 10 cm . 10 cm 12.6 •• 0.14 2.90 0.271 2.63 19.6 0.14 2.67 0.476 2.19 1 22.6. 0.14 2.20 0.573 1.63' • 25-3 0.14 2.11 0.676 1.42 27.6 0.14 I.64 0.738 0.90 " 1270 0T4~I J7U5 0.258 '. ~T779~ 18.6 O.41 2.95 0.444 2.51 2 22.0 . 0.41 2.54 0.550 1.99 • 25.4 0.41 2.21 O.665 1-54 27.0 0.41 2.06 0.720 1.34 13.0 . 0.82 3.91 0.283 3.63 18.3 0.82 3.95 0.437 3.51 3 22.0 0.82 3.40 0.550 2.85 25.0 0.82 3.01 0.651 2.36 26.8 0.82 3.00 0.710 2.29 11.0 1.10 -4.91 0.230 4.68 17.6 1.10 4.37 0.416 3-95 18.4 1.10 4-45 0.439 4.01 4 21.8 1.10 4.47 0.545 3.92 24.7 1.10 •4.43 0.642 3.79 • • - •- 27.1- 1.10 .4.39 0.722 3.67 27-5 0.24 2.33 0.736 1.59 5 27.5 0.76 3.06 0.736 2.32 27.5 0.82 3.13 0.736 2.39 27.5 1.33 4.15 0.736 3.41 27.5 2.00 4.17 0.736 .3.43. 18.5 O.34 3.47 0.441 3.02 18.5 0..72 4.78 0.441 4.34 6 18.5 1.07 5.22 0.441 4.78 18.5 1.54 5-52 0.441 5.08 18.5 1.79 6.68 0.441 6.24 Discussion 1) -- • : • - Decay of 02(^g). '.-..]. -The following processes could contribute to the decay of 0 (!Ag) i n the absence of any added reagent- . . 0 2 ( ' A g ) kJ_> 0 2 ( * £ g ) h , P ( l 2 7 0 0 A ) (3) 0 2 ( ' A g ) + w a l l JM> 02(JX'g) + w a l l (4.) 0 2 ( ' A g ) + 0 2 ( 3 X g ) M > 2 0 2 C Z g ) (5) 2 0?(kg) -Mils. 2 0 2 f Z l g ) -r-hP (6340A) (6) 2 0 2 ( ' A g ) -M% 0 2flg) + 0 2 ( ^ g ) (7) 2 0 2 ( ' A g ) 2 0 2 (8) where k(L), k(2), k(3), k(5), and k(6) are rate constants. - The rate constants^ for r a d i a t i v e decay k(L) and k(4) are 1.5/ x l O - / f .'...''sec"1 and 0.2S or (3±0.6)x 10~2 l/raole sec. respectively. These are many orders of magnitude too small to con-tribu t e to the decay i n our flow system and w i l l not be considered f u r t h e r . The experimental f i r s t order decay constant (kA). and the second order decay constant (kB) can be expressed i n terms of k0J, k(2), kO), ky, k(5), and k(6). k A = k(L) + kfc) + kp) 0 2 f e g ) (9) ' . k B * 144) + k(5) + k(6) (10) Let T represent the t o t a l concentration of oxygen T, = 0 2( jZlg) + 0 2 ( ' A g ) + other species ^ 0 2 f c g ) + 0 2 ( ' A g ) , (n) Then the equation 9 and 10 can be expressed as k A = kO)T (12) k B - k(5)+ k(6)- kD) (13) F i r s t order decay process. By p r o t t i n g k^  against the t o t a l c o n c e n t r a t i o n of oxygen (T), k^ ) and k(3) can be obtained from the i n t e r c e p t and slope r e s p e c t i v e l y . From.a l e a s t squares p l o t of the data l i s t e d i n Table 5, we have c a l c u l a t e d values of k(2) = ( 0 . 2 4 6 +.0.072) s e c " 1 and kfc) = ( 6 . 2 + 1 3 . 5 ) x 10 l/mol'e sec. Since the value of kp) l i e s w i t h i n the probable e r r o r , i t i s of l i t t l e s i g n i f i c a n c e . Twice the probable e r r o r i n a d d i t i o n to the value w i l l be used as an upper l i m i t f o r kt3). i ^ e . k(?)^  0 .33 x 10- 1/rnole sec. One can c a l c u l a t e the f r a c t i o n of c o l l i s i o n s t h a t are e f f e c t i v e by applying c o l l i s i o n theory. Let E be the s p e c i f i c e f f i c i e n c y of d e a c t i v a t i o n by r e a c t i o n (5 )'which i s expressed by the equation,' Number of molecules d e a c t i v a t e d by \ kthe r e a c t i o n (5) / E •= — : — _ (T o t a l c o l l i s i o n number between \ 02.('Ag) and 0 2t JZLg) i n an u n i t volume) 54. k3 N A N B V ^2 B k'3 2 AB (14) where k3: rate constant (cm /sec. molecule), k : . Boltzman constant. T: Kelvin temperature °K. JU.: reduced mass of 0 2(& g) and • 0 2 fe g) in this case. ($~AB: radius of oxygen.. N A Ng: number of molecules of 02(!Ag) and 02f.Zg) in an unit volume. Then the maximum efficiency of deactivation by reaction (5) becomes 2.2 x 10 which corresponds to one deactivation in>4«5 x 10 collisions. An analogous efficiency of deactivation by reaction (4) can be calculated using a similar equation 7 :^rate of decay by reaction (4) ^ E (Total number of collisions of 0 2(J^g) with the wall. N A V k2 i N AUS 55. (15) where V i s volume and S i s surface area corres-ponding to V. k(2): rate constant of reaction (2) c: i s mean molecular v e l o c i t y which i s • expressed by the formula N^: i s number of molecule of 0 2 ( A g ) i n an unit volume. Then the e f f i c i e n c y of deactivation by wall c o l l i s i o n becomes 6 x 10~ 6 which corresponds to one deactivation i n every 1.7 x. 10^ c o l l i s i o n s on the wall.at room temperature (23°C). Diffu s i o n to the wall might control the reaction (4)- I f t h i s i s . true the average time (tj)) required f o r a molecule to dif f u s e to the wal l i s much larger than the average time [ty) for a molecule to be deactivated at the wall. The value of t ^ can be calculated from the theory of Rrownian motion which gives r : i s diameter of reaction tube. where D is.the diffusion coefficient • -2 X i s the mean square particle displacement during the time tjj Since the diffusion coefficient i s inversely proportional to the pressure i.e.• D = D^ef) P^efyP (17) The c r i t i c a l pressure P above which diffusion i s important may be calculated from the relations t D > t ¥ . (18) and . 1 t w -~W) (19) The c r i t i c a l pressure i s found to be 7lJ rnm Hg at 273°K under these conditions, i f the value 2 0.18 cm /sec i s taken as the self-diffusion coefficient at 273°K. This pressure i s much higher than the pressure in the experiments. Therefore, the process of wall deactivation i s not diffusion limited'Under these experimental . conditions and wall deactivation w i l l be indepen-dent of pressure. For the reactions which are second order in 02('^g), the c o l l i s i o n efficiency can be calculated applying equation (14)., shown before.* Then the efficiency of deactivation * A factor of one half must be applied since the formula would count each c o l l i s i o n twice. by a l l second order reactions becomes 9.6 x 10" which corresponds to one deactivation in every 7 10 collisions. Second order decay processes From Table 5 the average values of the total second order rate constant k = 2 . 9 2 x lcA I •'mole' sec".' B . which from equation (13) is.equal to k(5) + k(6)-k(3) Since k(3) i s about 1% of kg i t w i l l be neglected i.e. i t w i l l be assumed k(5)+ k(6) = 2 . 9 x 10 4 £ mole'sec"/ The;.most reliable value of k(5) available i s that obtained by Arnold who observed the-rate of 02^^^ formation. The value she obtained i s 1.3 x 103. If this i s correct then the dominant second order decay in our system must be reaction (z).,.If the reaction produces two ground state oxygen molecules then the process i s spin allowed and could conceivably be rapid. On the other hand Arnold's value of k5 may be low (see Tablets) and hence i t i s s t i l l possible that k(5) = 2 . 9 x 10 4. As i s shown in Table-8, the values of the rate constants found in this study are comparable to the values obtained by some earlier workers especially those of Arnold's. TABLE 8 . Comparison of r a t e consts. obs. :by other i n v e s t i g a t o r s k(2) 0.178 s e c - 1 k(3) C 2.77 x 10 2 J^/mole. sec, 1.53 J2/mole. sec k(5) 1.3 x 10 3 //mole, sec, ) H 1.8 x 1 0 7 ± 0 , 5 f/mole sec. ) k(6) ^ 4.3 x 1 0 2 I/mole. sec. ) J 58. Present work 0.25 s e c - 1 ^ 3 . 3 x 10 i/mole. sec. 2 . 9 x 10^ A/mole. sec. I d e n t i f i c a t i o n of Products The reaction product of 2.3-dimethyl butene-2 with excited oxygen NMR. IR. and NIR spectrograms of the product are compared i n Table 9, 10, to those of 2j3-dimethyl-3-hydroperoxybc/tene--L taken 35 36 ^7 by Schenk,-^ Wexler, and other workers. The mass spectrogram of 2 ;3-dimethyl-3-hydro-peroxy bolene-1 taken by Winer and Bayes^ i s shown i n F i g . 15. The NMR spectrogram of the product i s quite consistent with that of 2.3-diniethyl-3r) hydroperoxy butene-1 which was produced by photosensitized autoxidation and ^2®2 oxidation of 2,3-dimethyl butene-2, except X. (position) and shape of the proton of the hydroperoxide group. Different values of -c are possible because, as i n the case of hydroxyl proton, intermolecular hydrogen bonding e f f e c t s can cause .the spectrogram to show a concentration and temperature dependence. For the-NMR measurement of the product, the product was not d i l u t e d with any solvent; on the other hand Wexler used carbon te t r a c h l o r i d e as a solvent to measure the NMR spectrogram of 2;3 dimethyl-3-hydroperoxy butene-1. 60. TABLE 9 NMR comparison A -6-CH, '8.67 B =C—CH3 8.21 C -C = CH 5.10 D -00 H (?) 1.07 (A:3:C:D) . - 1: obs. obs. Wexler ( s i n g l e t ) . 8 . 7 0 (doublet) 8.22 (doublet) (broad) 5-08 (sharp) 1.62 (broad) 1.98: 2.99: 6.03 (A:B:C:D) = ?: 2: 3: 6 Wexler TABLE 10, IR,'and NIR comparison Product (95-5%) W e x l e P 6 ) Wave No. Wave length* Wave 1 e.ngtb' cm" 831 (M) 12.0 11.9V 900 (3) 11.1 11.04 960 10.4 - ' 1012 9.88 ' 9.83 1039 9.63 1148 (S) 8.71 8.69 1170 8.55 8.51 1207 (!•:) •8.28 8.27 1298 7.70 7.68 1360 (S) 7.36 7.32 1375 (S) 7.28 7.25 1452 (S) 6.88 6.86 1642 (Ii) 6.09 6.04 1800 5-56 2985(S) 3.35 3400 (S) 2.94 .2.84 N.I.R. 2.107 2.067 1.765 1.730 1.689 1.676 1.628 1.443 Shenck Wave I £)ig b'-v 6 . 0 4 ( 3 7 ) a 2.94 2.118 ( 3 7 )b 1 . 6 3 { 3 7 )b 1.45 _u_ /o 20 J 1 UJ_[_ •9-0 J L 60 7o i 11 i 8o — * - i — / 0 0 /.20 Figure 15: Mass spectrogram of 2,3-diraethyl-3-hydroperoxybutene-l taken by Winer and Bayes. 64. To determine whether the hydroperoxy •group exists in the product-, an NIR spectrogram was taken to check for 1.45^ absorption which i s characteristic for -00H in the case of 2,3--dimethyl-3-hydroperoxy butene-1. Absorption at 1.443/* was found. This confirms the presence of -00H group in the product. There i s another possibility that the functional group was -OH instead of -00H. If i t i s true,' there should be an absorption at 1.425P- and also in the NMR - spectrogram of this product there should be a peak between TD=6 and 7 (see Fig. 16); but both of these were absent. . - • i The existence of CH2=C- can be shown by IR and NMR spectrograms. The IR absorption of .-6.09JLI shows the evidence of a terminal double bond and the NMR spectrogram can be explained In .terms of the different characteristics of the two protons attached to terminal double bond ( C H o = C - C H 3 ) . For these two protons (Hj_ and H2) of the ethylenic group, the unperturbed A B type quartet due to and H 2 i s shown in Fig. 17. The components of the doublet associated •with the H 2 proton are s p l i t into quartets by the H i r 1 1 I 1 1 1 Figure 17: NMR splitting doe t o A 8 system methyl group adjacent to the ethylenic group. Thus the value for the coupling constant between the ethylenic protons (H^ and.H2) i s found to be 1,4 cps which i s consistent with that of reference 40 Hr .4 cps). For the mass spectrogram, i t i s not surprising that the mass number of the parent could not be detected because this hydroperoxide i s probably unstable under electron bombardment. The cleavage of the 0-0 bond i s expected to be easy because of i t s relatively low bond energy (~5lKcal/mole in the case of hydrogen peroxide). Some of the main peaks are explained as follows. - t n « « FjCCOCH | I I I j I • i ^ UXI-..X\K.—L • on r H i Figure 18: M l IS spectrogram butene-1. of 3-methyl-3-hydroxy-C OOH / 4 ^ H C c—c-o 4 + . .-'OH HA > 4 = 4-1 C H 3 4 (C H,-c =q) + • cH, .CH, i t t - C + -CH, He, C - Q 4 <CHa 0 or H3c / C-"C.-=0 This i s merely one of many possible cracking schemes. Most of the small peaks are quite d i f f i c u l t to explain exactly, mainly because of the complicated cleavages and re-arrangements of the product. Winer and Bayes also took a mass spectrogram of the product produced under the gas phase oxidation of 2;3-dimethylt>utene-2 with singlet oxygen. Their spectrogram showed a cracking pattern d i f f e r e n t from the present work e s p e c i a l l y at h i g h v ^ value. The reason the bracking patterns were not exactly the same i s not c l e a r . I f they separated the product from the reaction mixture by gas chroma-tography i t i s quite possible that there existed some decomposed products which may show quite d i f f e r e n t cracking patterns. However i t should be noted that cracking patterns depend greatly . on the operation conditions as well as on the type of instrument used. The NMR, IR and NIR spectrograms are quite consistent with those of 2,3-dimethyl-3-hydroperoxybutene-1. Hence, i t may be concluded that the product of the reaction of 2,3-demethylbutene-2 with (^('Ag) i s "the hydroperoxide, whose formula i s V 5 C H A = C - C - C H , \ 1 G h U 0 0 H (2;3-dimethyl-3-hydroperoxybutene-l) Reaction product of 2-methylbutene-2 with excite oxygen As i s shown in the gas chromatogram, there are four main products (A.B.C.D.), Identi fication was attempted only for two (A and B). Product A A was separated from the reactant and other products by gas chromatography. Even -though the separation was quite successful there were s t i l l small amounts of impurities a l l of which vrere unknown. The collected samples contained more than 90 area% of A, NMR, IR and mass spectro-grams were taken for this separated fraction. According to the WMR spectrogram,. the ratio of protons in the quartet, t r i p l e t and singlet whose ~C(PPM) are approximately 4-0, 4.8 and 8.7 respectively i s about 1: 2: 6. The whole spectrogram was compared with that of 3-methyl-41 ' 3-hydroxybutene-l (See Fig. 18). The two spectrograms are almost i d e n t i c a l except for the pos i t i o n of the proton of -OH group.' However the NMR spectrogram of the f r a c t i o n has some other small peaks which were assigned as those of impurities. Hence, the skeleton of t h i s product A i s taken to be This compound has a. terminal ethylene group which i s an ABC system. This i s one of the more complex spin-coupling systems, and sets of calculated spectrograms, with various coupling constants and signs are given by Wiberg and 42 ' ' ' . " " " Nist . One witk a s i m i l a r pattern to the i^-Ii; spectrogram"'of t h i s product a i s shown i n F i g . 19. This proposed skeleton of A i s quite reasonable from a consideration of the reaction of 2,3-dimethyl butene-2 producing 2^, 3-dimethyl -2-hydroperoxybutene—1. Foote e t . a l . oxidized 2-methylbutene-2 by oxygen.'gas with the help of a photosensitizer under the i r r a d i a t i o n of l i g h t and also by the oxidant produced by the reaction of hydrogen peroxide with sodium hypochlorite. After the oxidation, the products were reduced immediately by trimethyl phosphite to CO o P j—' o e (—* p c+ CD Pi o CQ o 'E5 o. w • O 5 :4 x >• »> > r x >• x >• x x *• >» > f * J t C £ C > »• K r k > | i > > > > > K k > < > ) i i > » j - > > V >• X >>•> » > fc>^»xxx>x»'x it ** •- — — r -• • x 7 / 72. corresponding alcohols.. One of the a l c o h o l s , which was a main product f o r both processes was i d e n t i f i e d to be an unsaturated a l c o h o l whose s t r u c t u r e was CH,= C - C C H 3 M O H This a l c o h o l a l s o supports the proposed s t r u c t u r e of A because 0 2 ( ' A g ) i s produced by h e t e r o l y t j c . : cleavage of hydrogen peroxide. An e f f o r t was made to l o c a t e a proton resonance of the -00H group i n the range of ~C = 0 to t = 3, but no d e f i n i t e peak was found. This may be because of the broadening of tha t peak f o r somedunknown reasons. The IR spectrogram of t h i s f r a c t i o n shows the presence of an -OH group. The poss-i b i l i t y t h a t the -OH group e x i s t s as a hydroxy group i s excluded by the absence of any s i n g l e t peak i n the NMR spectrum i n the range *"C = 5 • 5 to "C = 7-0. There i s a l s o no p o s s i b i l i t y t h a t the product A i s a compound whose s t r u c t u r e i s ^ c - c - o o - c - c ^ because of the absorption of the -OH group i n the IR spectrum and a l s o because of i t s expected 72. high boiling point. Hence product A may be 3-methy1-3-hydroperoxy-butene-1, i.e. n OOH The mass spectrogram of A i s much too complicated to explain. • Some of the mass numbers can be explained by the same scheme shown in the case of 2;3-dimethyl-3-hydroperoxy-butene-l, but some of the highest peaks, for example, M/e = 7l and 59, are quite d i f f i c u l t to rationalize. This may be because of the ins t a b i l i t y of A under the high potential f i e l d and production of many complicated fragments. Product B As shown in the gas chromatogram after the separation, the separated fraction, which was expected to be mcstly B, contained only about 50%. The main impurity was around 5C;t,ofVA. There-fore, NMR, IR, and mass spectra-.;. 0 f this fraction showed both characteristics of A and B equally. To find new peaks in the NMR spectro-gram for 3, spectrograms of both fractions were compared and the peaks from A were cancelled out. By this operation, four sets of peaks were found belonging to product B with "C of 5-06 (broad), 74. •5.58 ( q u a r t e t ) , 8 . 2 7 ' ' ( d o u b l e t ) , a n d 8.79 ( d o u b l e t ) i n t h e r a t i o o f 5.8: 2.6: 7»3- 7.2 r e s p e c t i v e l y , w h i c h i s r o u g h l y 2: 1: 3'-'- 3- T h e s e s e t s a r e " a l s o c o m p a r e d w i t h t h o s e o f 2,3-dimethyl-3-• h y d r o p e r o x y b u t e n e - 2 . T h e b r o a d p e a k (~C = 5«06) • i s . a s s i g n e d t o t h e t w o g e m i n a l p r o t o n s o f a n - e t h y l e n e g r o u p w h o s e - o t h e r s u b s t i t u e n t i n c l u d e s a m e t h y l g r o u p . T h e p e a k o f t h e s e m e t h y l g r o u p p r o t o n s c a n b e s e e n a t t = 8.27 a s a d o u b l e t . . T h e q u a r t e t i s a l s o e x p e c t e d i f t h e c a r b o n , t o ^ w h i c h t h e p r o t o n i s a t t a c h e d , i s a d j a c e n t t o a • • m e t h y l , g r o u p . T h e s p i n - s p i n c o u p l i n g c o n s t a n t s o f t h e s e t w o c h a r a c t e r i s t i c p r o t o n s a r e c o m p a r e d . T h e y a r e b o t h 7 c p s . . ^'7hich i s c o n s i s t e n t w i t h t h a t f r o m r e f e r e n c e ^ ( 6 - 8 c p s ) . T h e c o m p -- a r i s o n o f t h e s p e c t r o g r a m o f t h e B w i t h t h a t o f 2 ; 3 - d i m e t h y l - 3 - h y d r o p e r o x y b u t e n e - l i s s h o w n . i n t a b l e 11. I n . t h e NMR s p e c t r o g r a m o f t h i s s e p a r a t e d f r a c t i o n ( d i l u t e d w i t h C C l^ " ) , t h e r e i s a b r o a d p e a k . w h o s e "C v a l u e i s a b o u t 2.35- T h i s c a n b e c o n s i d e r e d a s b e i n g d u e t o t h e p r o t o n o f a h y d r o p e r o x i d e g r o u p . T h e p o s i t i o n o f t h i s p e a k m i g h t d e p e n d o n c o n c e n t r a t i o n b e c a u s e o f i n t e r -- • m o l e c u l a r ' h y d r o g e n b o n d i n g e f f e c t s . F o r t h e r e a s o n s m e n t i o n e d a b o v e , t h e p r o d u c t 3 i s t h o u g h t 75 to be 2-methyl-3-hydroperoxy butene-1 i . e . C ti ^  / C H 3  C ^ C - C - H Foote e t . a l also found the corresponding * alcohol, that i s , 2-methyl-3-hydroxybutene-l, a f t e r the reduction of the oxidation mixture of 2-methylbutene-2 with" hydrogen peroxide (and.sodium hypochlorite) or by photosensitized autoxidation. This fact also supports the proposal that 2-methyl-3-hydroperoxybutene-l i s one of the products under the conditions used. TABLE 11 Comparison of NMR spectrograms product B 2.3-dimethyl~3-hydroperoxy-butene-1 = CH 2 5-06 (broad) 5.10 (broad) =a - CH3 8.27 (doublet) 8.21 (doublet) -CH3 8.79 (doublet) 8.67 (singlet) hyC-C-H 5-58 (quartet) -00H (?) 2.35 (broad) 1.07 (singlet sharp) From mass and IR spectrograms i t can be said that both A and B are quite s i m i l a r compounds but no further i n v e s t i g a t i o n has been made because the f r a c t i o n used f o r mass ;and IR spectrograms i s found to be an almost equivalent mixture of A and. B. I t i s very i n t e r e s t i n g to know that the products produced by the reaction of o l e f i n s with C ^ l ' A g ) i n the gas phase are i d e n t i c a l to those produced by photosensitized autoxidation•and by hydrogen peroxide(with 'sodium hypochlorite) oxidation of o l e f i n s . In the case of gas phase oxidation with discharged oxygen (with d i s t i l l -ation of mercury) and hydrogen peroxide oxidation, i t Is clear that the sin g l e t oxygen molecule i s the oxidant. Therefore, the mechanism could be considered to involve a s i n g l e t oxygen molecule on the other hand, i n the case of photosensitized autoxidation, two possible mechanisms were discussed by Foote and Wexler i.e:;. A) Sens "'"Sens 1Sens > 3sens 3Sens + 3 0 2 > • Sens - 0 0 • • Sens - 0 0 . + A —> A 0 2 + Sens 77 B) Sens "'"Sens ISens ——> 3sens 3Sens + 3CU > Sens + 10 1 2 0 2 .+ A —-> A0 2 Where Sens i s a photosensitizer and A i s an acceptor. In view of the r e s u l t s of those experiments i n which s i n g l e t oxygen molecules were used as an oxidant, mechanism B) i s preferable. I f t h i s i s true, the mechanism of oxidation of o l e f i n s with s i n g l e t oxygen molecules can be suggested. The s i n g l e t oxygen molecule may be e l e c t r o p h i l i c . '0 = a <—> |0 = 0.i As i n the case of bromination of o l e f i n s , t h i s e l e c t r o p h i l i c s i n g l e t oxygen molecule might attack the double bond of an o l e f i n giving some intermediate. Then the migration of hydrogen (proton) might make a hydroperoxide. Therefore, the higher the.electron density of the double bond becomes the more preferable i t i s f o r the o l e f i n to be attacked by t h i s e l e c t r o p h i l i c oxygen molecule i f we neglect s t e r i c e f f a c t s . The methyl group has a tendency to donate electrons to an 7 8 . adjacent carbon. Therefore, the more methyl groups there are attached to the double bond the more e a s i l y an attack might be made by ; e l e c t r o p h i l i c oxygen molecule. Q u a l i t a t i v e l y t h i s i s confirmed by the observation that ;2 73-dimethylbutene-2 reacted with excited oxygen -molecules more e a s i l y than 2-methylbutene-2. In the case.of propylene no product -was found with the reaction of si n g l e t oxygen molecules. The r a t i o of products of oxidation •'-•of. 2-methylbutene-2 with s i n g l e t oxygen molecules . i . e . the r a t i o of 3-methyl-3-hydroperoxybutene-l to 2-methyl-3-hydroperoxybutene-l was two. 28 Foote et a l _ reported a product r a t i o of one. Both of these r a t i o s are u n l i k e l y i f the i n t e r --mediate shown below has an equal p r o b a b i l i t y •of a hydrogen migration from any methyl group attached to the double bond carbons; but they are acceptable i f the s h i f t of the oxygen molecule attached to the double bond i s easier to the carbon atom with' more methyl group. Thus the mechanism of the oxidation of mono-olefins with the singlet state of oxygen m o l e c u l e s m i g h t b e w r i t t e n a s f o l l o w s V • / • ••-> /--c< u uc oort T h e i d e n t i f i c a t i o n o f t h e p r o d u c t o f t h e r e a C t i O f i o f c i s - b u t e n e - 2 w i t h s i n g l e t o x y g e n m o l e c u l e s w a s n o t t r i e d b e c a u s e o f i t s v e r y s m a l l a m o u n t s . F r o m a k n o w l e d g e o f o t h e r p r o d u c t s i d e n t i f i e d i t i s e s t i m a t e d t o b e 3 - h y d r o p e r o x y b u t e n e - l o r i t s d e c o m p o s e d p r o d u c t s . 3) D e c a y o f 0 2 ( ' A g ) w i t h 2,3-dimethylbutene-2 T o f i n d t h e o r d e r w i t h r e s p e c t t o t h e o l e f i n , l o g ( - v o ) w a s p l o t t e d a g a i n s t l o g R o ( i n i t i a l f l o w r a t e o f o l e f i n ) f o r r u n s w i t h t h e s a m e f l o w r a t e s o f t o t a l o x y g e n a n d C^ ' A g ) . T h i s g r a p h i s s h o w n i n F i g 20. T h e s l o p e s o f t h e t w o l i n e s s h o w t h a t t h e o r d e r o f o l e f i n i s q u i t e c l o s e t o o n e h a l f . H e n c e , t o f i n d t h e o r d e r w i t h r e s p e c t t o O g t ' A g ) , l og (-V0//R0 ) w a s p l o t t e d a g a i n s t l o g I^ . ( i n t -e n s i t y o f e m i s s i o n a t 6340A" a t t = o ) . ( S e e F i g 21) I f t h e o r d e r o f o l e f i n i s r i g h t a n d t h e r a t e e q u a t i o n i s e x p r e s s e d i n a s i m p l e f o r m t h e p l o t l o g ( - - V O / 7 R O ) a g a i n s t l o g I ? s h o u l d s h o w a s t r a i g h t l i n e . . H o w e v e r , a s i s s e e n i n F i g . 2 1 , . t h e p o i n t s a r e n o t o n o n e l i n e . M o r e o v e r t h e t r e n d o f t h e s e p o i n t s s h o w s t h a t t h e v a l u e o f l o g ( - V § / R o ) d e c r e a s e s a s t h e v a l u e o f l o g l e i n c r e a s e s . T h e s e o b s e r v e d f a c t s s i m p l y m e a n 0.5 Figure 20: Relationship between log(-v 0) and logR,. ir-c 3 V ^ J i.& [• o ^ o ° -l-O l.l I.J2- •1-3 5 f T / o A 5 D ? V •r O 6 0 Jog I, 1.6 Figure 21: Relationship between log (-Tg//R). and log 1^ . that the. formula of the rate equation f o r the decay of O^l '^g) with t h i s o l e f i n i s not simple. It might be doubted that the i n t e n s i t y of emission o at 6340 A had a l i n e a r r e l a t i o n s h i p against the square of (^('.Ag) under these reaction conditions. To confirm t h i s l i n e a r r e l a t i o n s h i p the excess energy i n the flow and the i n t e n s i t y of emission at 634OA were measured by the isothermal calorimetric detector and photomultiplier resp e c t i v e l y . The relationship' between them i s shown i n Fig 22. I t i s seen i n F i g . 22 that a good l i n e a r r e l a t i o n -ship between V / I ^ ^ Q (square root i n t e n s i t y of 6340A) and the .concentration of excited oxygen molecule have been kept during the reaction. The l i n e does not pass through the o r i g i n , presumably because the i n t e n s i t y at 6340A was measured a few cm (around 4 cm) ahead of the detector. The negative order of (^(Ag) ± s quite d i f f i c u l t to understand. This may be because of the fa c t s which were not taken into account. For example, some species may prevent the decay of 0 (!^g). It might be considered that the reason i s the inhomogeneity of the temperature. To check t h i s point, the flow of excited oxygen molecules was cooled down quickly from outside of the reaction tube with water just a f t e r the discharge but no difference was observed. Because of the reason discussed above, i t i s concluded that the decay process of (^('Ag) with o l e f i n i s quite complicated. 7 0 < 1 •—<—• 1 1 1 • • • • i i i .. 0 . ' 2 3 4 5 6 7 8 <? 10 II \x 13 ( ca. lor j meter ) Figure 22: Relationship between excess energy i n 'the stream and . 83-It should be possible to investigate these reactions at very high and very low concentrations of reactant and s i n g l e t delta, or by d i l u t i o n with an i n e r t gas. Under these conditions simpler k i n e t i c r e l a t i o n s h i p s may be observed so that the reason f o r the complex behavior observed i n the present work could be understood. REFERENCES. . 1. R.S. Mulliken, Phys. Rev., }2> 880 (1923) 2. G. Herzberg, Nature, 133, 759 (1934) 3. J. F. Noxon and A.V. Jones, Nature, 196, 157 (1962) 4. J.F. Noxon and T.P. Markham, J. Geophys. Res., 68 • 6059 (1963) 5- J.W.'Ellis, and H.O. Kneesr, Z. Phys, 86, 583 (1933) 6. J. Kaplan, Nature, 15_£, 673 (1952) 7- L.M. Banscorab, Phys. 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