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UBC Theses and Dissertations

A. The anodic oxidation of Benzene. B. The effect of certain chemicals on the hydrolytic activity of.. Archibald, Reginald MacGregor 1932-10-24

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UlB.C. LIBRARY * A. THE AHODIC OXIDATION OF BENZENE. B. THE EFFECT OF CERTAIN CHEMICALS OU THE HYDROLYTIC ACTIVITY OF RICINUS AID PORK PANCREAS LIPASE. BY Reginald MacGregor Archibald A Thesis submitted f o r the Degree of MASTER OF ARTS i n the Department of CHEMISTRY The U n i r e r s t i y of B r i t i s h Columbia A. THE ANODIC OXIDATION OF HENZEHE. CONTENTS. I # Introduction «1 Purpose .. .1 Summation of factors to "be considered 1 Means of moderating the intensity of oxidation 1. concentration, solubility and solvent.....6 2. decrease overvoltage (a) AC on DC ...8 ( D ) intermittent....10 3. choice of anode material.................11 4. catalysts, etc. ...14 5. cathode cooperation, diaphragm, etc. 14 6. size of anode, current density, etc 15 7. power factor 16 8. other factors 17 Suggestions 18 Pros, and Cone, of Electrochemical manufacture..19 II. Previous Work 21 Mechanism of Electro-oxidation 21 III. Experimental. ...24 Method 24 Apparatus} c e l l and ele c t r i c a l hook-up 25 Phenol tests. 26 Rectified Current .28 Types of current used. ,29 CONTENTS cont'd. Page IT. R e s u l t s .30 Decomposition p o t e n t i a l s . 30 By-products ,31 Phenol y i e l d s 33 V. D i s c u s s i o n of Resultw. 35 V I . Summary 36 V I I . B i b l i o g r a p h y 38 Figures and Graphs. Figure 1 Figure 2 Figure 3 Figure 4 to face to face to face to face page 24. page 2 5 . page 2 5 . page 29. Graph I to face page 30. Graph II to face Graph I. Graph III to face fraph II. THE ANODIC OXIDATION OF BENZENE. I. Introduction*  Purposes The investigation was carried on with a view to finding (l) whether or not there is truth in the predictions of several organic electrochemists, that on electrolytic oxidation ofbenzene the product f i r s t formed is phenol, and i f this be true, then to discover (2) what factors influence the y i e l d of this product, thereby determining by what means the y i e l d can be increased. Summation of factors to be considered: Of the two reactions encountered in organic electro chemistry, v i z . oxidation and reduction,^ the former is the least developed. The greater d i f f i c u l t y experienced in controlling the factors which influence the reactions of organic electro-oxidation have led, in the past, to intricate courses of reactions, resulting in low yields and disappointment. Hence electro-organic chemistry has not been regarded as a very f r u i t f u l f i e l d for commercial manufacture. Especially i s this true in the case of aromatic compounds. For, the fatty compounds, being, as a rule, the more readily oxidized, break up in stages t i l l 1. Trans. Am. Electrochem. Soc, 40, 109, (1921). 2. f i n a l l y , they are converted into carbon dioxide and water, whereas the aromatic compounds form phenolic condensation products of a resinous nature. Though d i f f i c u l t i e s have been many, and the results, as a rule, disappointing, nevertheless, experiments in this f i e l d have been numerous and some, expecially those involving the use of catalysts, have led to interesting results. It has long been known that anodic oxygen oxidizes aromatic compounds by the introduction of hydroxy! groups. If the reaction at the anode could be sufficiently controlled, benzene could be converted into the relatively more valuable commercial product, phenol. Fichter and other elctro-organic chemists believe that phenol is the f i r s t oxidation product of benzene. Brockraan 1 refers to a work of Fichter and Uhl 2 in which these la s t , using benzene with a twice normal solution of sulphuric acid at 60° in an atmosphere of carbon dioxide, obtained at a platinum anode, a small quantity of phenol. In a later work Fichter states that he was unable to prove that phenol is the f i r s t oxidation product of benzene. A search of the available literature has brought to light no other cases where phenol has been obtained e l c t r o l y t i c a l l y 1. "Electro-organic Chemistry H (1926). 2. Helv. ChiBi. Acta, 3, 22, (1920). 3. Trans. Am. Electrochem. Soc, 4j5f 112, (1924). 3. from Mnz«ne i t s e l f . However, Hoppe-Seyler 1 obtained from benzene, water, and p a l l a d i u m hydride sponge i n the presence of a i r , s u f f i c i e n t phenol to detect q u a l i t a t i v e l y . Leeds ^ observed that i n time, a very d i l u t e s o l u t i o n of hydrogen peroxide converted benzene d i r e c t l y to phenol. Nencki 3 found t h a t oxygen of the a i r i n the presence of sodium hydroxide converted benzene to phenol. Cross, Bevan and Heiberg, by using f e r r o u s sulphate w i t h two molecular weights of hydrogen peroxide to one of benzene, o x i d i z e d 10 g. of benzene o b t a i n i n g 1.5 g. of phenol. Undoubtedly t h i s i n d i c a t e s t h a t phenol i s the f i r s t , (or at l e a s t one of the f i r s t ) , products of o x i d a t i o n of benzene. The f a c t t h a t o x i d a t i o n w i t h hydrogen peroxide y i e l d s , v e r y o f t e n the same products as does anodic oxygen, together w i t h the f a c t t h a t hydrogen peroxide o x i d i z e s benzene t o phenol, would lead one to expect to f i n d phenol as one of the products of e l e c t r o - o x i d a t i o n of benzene. There are s e v e r a l reasons f o r the f a c t t h a t under or d i n a r y c o n d i t i o n s phenol has not been detected as a product of e l e c t r o l y s i s . F i r s t , the process of e l e c t r o l y t i c 1. Ber. 12, 1552. 2. Ber, 14, 975. 3. Ber. 14, 1144. 4. Ber. d Deut. Chem. Ges. 33, 2017. 4. oxidation is so hard to control that the reaction proceeds past the phenol stage, and higher oxidation products are formed. Second, "benzene is highly resistant to oxidation being oxidized appreciably only by ozone, hydrogen peroxide, mono persulphuric acid, and by the most effective of a l l oxidizing agents, anodic oxygen. Phenol, on the other hand is relatively more easy to oxidize. The more the benzene nucleus is saturated with oxygen, the more readily decomposition into oxalic acid, carbon dioxide,etc., takes place. Hence phenol, as soon as i t is formed, being a better depolarizer than benzene, is almost completely oxidized to higher products before more benzene is converted into phenol. Or, in other words, with respect to certain compounds, there is an equilibrium set up in which the concentration of phenol is very low. Third, benzene in most electrolytes* is much less soluble that phenol. Hence a sufficient concentration of reactant cannot be obtained to act as a good depolarizer. As a result, the anode reaction is slow and incomplete. The product phenol, however, being quite soluble in the electrolyte, takes the place of the benzene as a depolarizer and is oxidized to a higher state. Fourth, as a result of the insolubility of benzene, i t is impossible to regulate closely the voltage to the oxidation potential, i.e., to the voltage $ust sufficient to oxidize "benzene to i t s f i r s t stage of oxidation. Failure to overcome these d i f f i c u l t i e s has led experimenters to obtain 5. from benzene the following products, p-p' diphenol o-p* diphenol quinone <- hydroquinone — — — — - q u i n o l and catechol 1 * with diaphragm butyric maleic acid and p-benzoquinone formaldehyde succinic racemic acid and formic and oxalic tartaric acids and or withdiaphragm carbon dioxide and fumaric C 4 H 4 ° 5 a n d C 7 H 6 G 4 ffl»P«93 Also n-valeric and malonic acids, o-hydroxyphenol,ethers, diphenyltetrahydroxydiphenol, dihydroxydiphenol ester, phenolic resins, etc. There appear to be two possible ways of stopping the oxidation as soon as i t reaches the phenol stage. F i r s t by removing the phenol from the electrolyte as soon as i t is formed and second, by moderating the intensity of the electrolytic oxidation. So far, the f i r s t step has not been accomplished. D i s t i l l a t i o n of phenol even from a solution of a stronger acid does not take place (unless the latter has a higher boiling point), since the concentration of the phenol is so very small. Precipitation of the phenol, or some compound of phenol from the electrolyte would s h i f t the reaction equilibrium in the desired direction and would prevent further oxidation, since the phenol could no longer act as a depolarizer. But a l l known means of precipitation are either too expensive, or else interfere 6. w i t h the d e s i r e d r e a c t i o n or e l e c t r o l y s i s . So f a r , no means of washing out the phenol from the e l e c t r o l y t e by the use o f another l i q u i d immiscable w i t h the a n o l y t e , which i s s u i t a b l e to t h i s p a r t i c u l a r process have been devised. The second expedient, v i z . that of moderating the i n t e n s i t y of e l e c t r o l y t i c o x i d a t i o n seems most u s e f u l . T&ere are many ways of doing t h i s , and the most of these depend on the r e g u l a t i o n of the voltage used,--hence a l s o of the e f f e c t i v e pressure and c o n c e n t r a t i o n of anodic oxygen. The f i r s t and most obvious way i s t o increase the c o n c e n t r a t i o n of the benzene i n t;he e l e c t r o l y t e so that benzene r a t h e r than phenol w i l l act as the d e p o l a r i z e r . In the p a s t , the e l e c t r o l y s i s of benzene has been c a r r i e d on i n d i l u t e s u l p h u r i c a c i d s o l u t i o n s in which benzene i s i n s o l u b l e * I t i s probable.' that the primary products are the same w i t h a l k a l i n e s o l u t i o n s as w i t h s u l p h u r i c a c i d s o l u t i o n s except that new c o m p l i c a t i o n s set i n owing to the i n s t a b i l i t y of quinone i n a l k a l i n e s o l u t i o n s . U n f o r t u n a t e l y most e l e c t r i c a l l y conductive s o l v e n t s and aqueous e l e c t r o l y t e s do not d i s s o l v e benzene, and according t o F i c h t e r , even the f i n e emulsions produced by vigourous s t i r r i n g are f a r from being as e f f e c t i v e as t r u e s o l u t i o n s . However BrockmanI says t h a t a s o l u b l e c a t a l y s t i s s u f f i c i e n t to make up f o r a poor s o l v e n t . Sodium acetate and 1. " E l e c t r o - o r g a n i c Chemistry," p 15. (1926). 2. J . Chem. Ind. Japan, 24, 567 (1921), 7. a l c o h o l 1 have "been used to increase the s o l u b i l i t y of the r e a c t a n t , hut the f i r s t substance does so only s l i g h t l y and the l a t t e r becomes i t s e l f , the d e p o l a r i z e r . The problem then, i s to f i n d another more s u i t a b l e s o l v e n t . I t i s to be expected th a t the product w i l l vary w i t h the solvent used. The i d e a l s o l v e n t f o r t h i s r e a c t i o n would (1) d i s s o l v e l a r g e q u a n t i t i e s of benzene, (2) have a low s p e c i f i c r e s i s t a n c e , (3) be not too v o l a t i l e , (4) be one i n which phenol i s i n s o l u b l e , ( s i n c e i t s removal from the s o l u t i o n prevents f u r t h e r o x i d a t i o n ) . (5) be a t t a c k e d only s l i g h t l y by the e l e c t r i c c u r r e n t . (6) be m i s c i b l e i n a l l p r o p o r t i o n s w i t h water, and (7) i f p o s s i b l e , be inexpensive. P y r i d i n e , e s p e c i a l l y w i t h aromatic compounds, has a tendancy to form t a r r y substances which r e s u l t i n l o s s of o m a t e r i a l . G l a c i a l a c e t i c a c i d to which has been added a s m a l l amount of water f u l f i l l s . a l l the above requirements except (2) and ( 4 ) . This w i l l not conduct the e l e c t r i c c u r r e n t a p p r e c i a b l y , (not n e a r l y as w e l l as w i l l a l i t e r of water w i t h a few c c . of a c e t i c a c i d } . But i f instead of water, a few c c . of concentrated sodium hydroxide s o l u t i o n are added, the s o l u t i o n becomes a good conductor of e l e c t r i c i t y and the benzene i s s t i l l s o l u b l e . The a c e t i c a c i d i s 1. Ber. m_p 1942, (1894). 2. H. D. Law, J . Chem. Soc., 89, 1437, (1906). 8. only slightly attacked. Bourgoin 1 found that of a l l the acids tried, acetic was the hardest to electrolyze,--especially •when concentrated. The glacial acid diluted with an equal volume of water gave 29.7% of oxygen and 2.3% of carbon dioxide. Hopfgartner 2 using anhydrous sodium acetate in gla c i a l acetic acid with platinum electrodes got 49.28% carton dioxide, 1.17% ethylene, .16% of oxygen, 21.06% of ethane and 27.85% of hydrogen ("by volume). Warming and the presence of al k a l i decreased the yield of ethane. Other products are carbon dioxide, methyl acetate, methyl carbonate, methyl formate and formic acid. The second means of moderating the intensity of oxidation is by decreasing the overvoltage of oxygen at the anode and the oxidation potential of the electrodes. The oxidizing power of an anode depends, in part, on the potential difference between the anode and the solution. The decrease in oxygen overvoltage can be accomplished, to some extent, by the superimposition of alternating on direct current, Goodwin and Knobel have studied the effect of alternating current on overvoltage, at platinum, copper, and lead electrodes. By the use of a variable frequency generator which gave a sinusoidal current wave, they experimented over the range of 2 to 100 cycles per, sec. 1. Ann. Chim et P&ys. (4) 14, 157, (1868). 2. HOnatsch 32, 523-61. Chem Abst. 5_, 3438. (1911). 3. Trans. Am Electrochem, Soc. 3*7, 617, (1920). They found that the decrease in overvoltage was a function of the ration alternating current and was independent of direct current the material of the electrodes and of the current density. They state that the effect is negligible when the ratio is less than .7 and reaches a maximum when the ratio is 3.2. There i s , however, some difference of opinion as to whether or not there is a minumum value which must be exceeded before an appreciable effect is produced. The effect increased slightly, (50mv. over the range studied), as the frequency was diminished. The power factor has a small influence , the change from 0 lead to .5 lag giving a difference of 30 mv. The decrease of i r r e v e r s i b i l i t y of the direct current electrode process i s said by Cooper to produce remarkable effects at frequencies below 10 cycles per sec. 1 By the superimposition of alternating an direct current, the retardation phenomenon and passivity in anodic metal solution can be eliminated and the limiting current density at which metal solution ceases can be raised, 2 Though most of the work has been concerned with the effect of overvoltage of hydrogen at the cathode, Grube and 3 Dulk observed that a high ratio of alternating current direct current lowered considerably the overvoltage of oxygen at platinum anodes. Oxygen was obtained at a potential less positive 1. Trans. Farad, Soc, 18, 102, (1922). 2. Marsh, Proc Roy. Soc, A. 97. 124, (1920). 3. Zeit. Elektrocheat., 24_, 237, (1918). 10. than the r e v e r s i b l e v a l u e . Marie 1 found t h a t when o x i d i z i n g a l c o h o l the v o l t a g e at a plat i n u m anode i n an a c i d medium rose from .7 to 1.1. He could c a r r y on the o x i d a t i o n a t the lower v o l t a g e by usi n g an i n t e r m i t t e n t c u r r e n t . This simply prevented p o l a r i z a t i o n . R e i t l i n g e r , 2 by usi n g a l t e r n a t i n g c u r r e n t superimposed on d i r e c t c u r r e n t , was abl e t o reduce the p o l a r i z a t i o n to such an extent that an a l c o h o l gave the corresponding aldehyde r a t h e r than the a c i d which r e s u l t e d when d i r e c t c u r r e n t only* was used. That i s , by the use of a l t e r n a t i n g on d i r e c t c u r r e n t , the e f f e c t i v e v o l t a g e or o x i d a t i o n p o t e n t i a l i s lowered so th a t products can be obtained which are intermediate between the r e a c t a n t s and the products obtained w i t h d i r e c t current alone. These phenomena a l l p o i n t to the p o s s i b i l i t y of r e g u l a t i n g the i n t e n s i t y of o x i d a t i o n by the superimposition of a l t e r n a t i n g on d i r e c t c u r r e n t , but w i t h platinum anodes t h i s expedient had the disadvantage of causing excessive c o r r o s i o n of the e l e c t r o d e s . An expedient c l o s e l y a s s o c i a t e d w i t h t h i s i s the use of an i n t e r m i t t e n t , (though not a l t e r n a t i n g ) , c u r r e n t . In the f o l l o w i n g experiments such a current has been obtained by the use of tantalum e l e c t r o d e s i n a c i d s o l u t i o n . The a l t e r n a t i n g current of the d e s i r e d v o l t a g e was a p p l i e d . 1. C h e l O b s t . , 32, 4345^. Compt Rend, 2. Z e i t . f Phys. Chem., 44, 81, (1903). 3. See a l s o Trans. Am.Electrochem. Soc., 41, 151, (1922). 11. The tantalum e l e c t r o d e almost completely r e c t i f i e d t h i s c u r r e n t . The t h i r d means of moderating the i n t e n s i t y of the e l e c t r o l y t i o o x i d a t i o n , r e l a t e d i n some ways to the second, i s i n the choice of proper anode m a t e r i a l . The choice of conductors f o r an anode i s r a t h e r limited,--much more l i m i t e d than i n the case of the cathode,--since many metals s u i t a b l e f o r cathodes are attacked at the anode. The choice f o r a l k a l i n e s o l u t i o n s i s l i m i t e d to platinum, p a l l a d i u m , i r i d i u m carbon, i r o n , and n i c k e l , ( i n the absence of ammonium s a l t s ) . In a c i d s o l u t i o n s we can use carbon i n the form of Acheson gr a p h i t e ( i n s o l u t i o n s c o n t a i n i n g C I " ) , p l a t i n u m ( i n absence of h a l i d e s ) , and l e a d o r l e a d peroxide ( i n s u l p h u r i c a c i d s o l u t i o n s w i t h s p e c i f i c g r a v i t y up to 1.6, or s o l u t i o n s w i t h anjr c o n c e n t r a t i o n s of phosphoric a c i d , n e u t r a l sulphates, phosphates, carbonates and chromates). Carbon has the disadvantage of d i s i n t e g r a t i n g mechanically and magnetite has too low a c o n d u c t i v i t y . Copper i s a s u i t a b l e anode f o r moderate o x i d a t i o n s , but i s s l o w l y attacked and deposited on the cathode. O x i d a t i o n i s s a i d to proceed most v i o l e n t l y at smooth platinum anodes. 1 Next to these are l e a d d i o x i d e anodes. Iron and n i c k e l ( e s p e c i a l l y spongy n i c k e l ) anodes have the lowest overvoltage as shown by the 1. F i c h t e r , Trans. Am. Electrochem. Soc., 4j5, 110, (1924). 12. following table. Electrode P . D . Electrode P . D . STetal Metal An 1.75 Pt (platinized) 1.47 Pt (smooth) 1.67 go 1.36 1.53 Ni (smooth) 1.35 i * 4 ? Ni (smooth) 1.28 The oxygen-hydrogen c e l l voltage is 1.22  As mentioned above, Fichter considers oxidation nore violent at smooth platinum electrodes than at lead dioxide anodes. However, i t is to be noted that in certain cases this is true only as regards the nucleus, the reverse being true of the side chain. For, Elbs 1 found that at smooth platinum anodes p-nitrotoluene oxidized to p-nitrobenzyl alcohol and p-nitrocresol, while lead dioxide anodes yiel d p-nitroben?oic acid. This probably has some thing to do with the difference in the tendency to form molecular oxygen at the two anodes. At the anode where molecular oxygen is most easily formed, the oxidation of the side chain would be expected to be most energetic, while the oxygen at the other anode would attack chiefly the nuclear hydrogens. For Fichter and Stocker have found that anodic, (supposedly atomic), oxygen attacks the nucleus before the side chain. This is also known to be the case with halogens. It is well to remember, when  1. Z. f . Elektrochem., 2, 522, (1896). 2. Ber. 4 7 , 2003, (1914). 13. choosing anodes for use with alternating current, that the greatest effect of the superimposed current is noticed when the metal electrode is covered with i t s insoluble s a l t . It is to be expected that the products which can be obtained at different kinds of anodes w i l l vary somewhat due to the difference in overvoltage of various electrodes and also due to the catalytic effects of certain anode materials. Which of these two influences is the most important is a subject of debate. The relative effect of each factor varies, probably, for each new set of conditions. Iron and nickel anodes in alkaline solutions are good for oxidations only at high current densities.l It is to be remembered too, that electrodes of platinum in particular, do not always behave as they are expected to. The nature of the surface, whether smooth or spongy,— whether or not the electrodes have been anodically or cathodically polarized, and the past history of the electrodes arw- factors which have decided influence on the course of £he electrolytic processes. 2 Prepolarization seems to Convert the electrode into a very labile and active condition which is not, as yet, understood. One would expect the mildest oxidation from an electrode which had never been used as a cathode.  1. D.I.P. 297019,(1900), and 141343 (1902). 2. Brockman's "Electro-organic Chemistry," p37. (1926). 14. The f o u r t h expedient i s the use of s a l t s of m u l t i v a l e n t metals such as vanadium, cerium, manganese and, (with diaphragm o n l y ) , chromium, 1 which act as c a r r i e r s or c a t a l y s t s . These speed up a b s o r p t i o n of oxygen by the d e p o l a r i z e r and increase the e l e c t r i c a l e f f i c i e n c y . I h i s expedient, a c c o r d i n g to Brockman, i s most u s e f u l where the d e p o l a r i z e r i s i n s o l u b l e i n the e l e c t r o l y t e . The o x i d a t i o n i s thought to proceed q u i t e e a s i l y without the c a t a l y s t s where the d e p o l a r i z e r i s s o l u b l e . A f i f t h means of c o n t r o l l i n g the i n t e n s i t y of the o x i d a t i o n i s the cooperation of the cathode,--i.e., the omission of a diaphragm. Some o x i d a t i o n products from the anode are reduced p a r t i a l l y , at the cathode. I f i n i t i a l r e d u c t i o n of the d e p o l a r i z e r a t the cathode, and the use of a diaphragm are u n d e s i r a b l e , excessive cathodic r e d u c t i o n can be avoided by the use of a cathode of small a r e a , i . e . by having a l a r g e cathode current d e n s i t y which causes most of the cathodic hydrogen to eacape i n the molecular form. Or, i n s t e a d , one may add small amounts of calcium c h l o r i d e or c a l c i u m s a l t s of r e s i n a c i d s , or, ( i n the case of n e u t r a l or s l i g h t l y a c i d s o l u t i o n s ) , s o l u b l e chrornate. 2 This l a s t forms a t h i n s k i n of chromic oxide over the cathode surface a c t i n g as a diaphragm and preventing cathodic r e d u c t i o n of the anode products. An a l k a l i n e s o l u t i o n 1. Trans. Am. Elektroehem., Soc., 4jD, 123, (1921). 2. Z. Elektroehem., 9, 583, (1903). 15. makes r e d u c t i o n more d i f f i c u l t and hence checks the e f f e c t of the cathode. The a d v i s a b i l i t y of the use of a diaphragm seems to be a p o i n t of debate. 1 The mechanical d i f f i c u l t i e s of c l o g g i n g , hardening, decomposition, heating and incress&d r e s i s t a n c e which at f i r s t made the diaphragm seem an unmitigated nuisance, have been overcome, even i n the presence of t a r r y byproducts, by the use of the " E l e c t r o - f i l t r o s . " This type of diaphragm, however, i s not s u i t a b l e f o r use i n s t r o n g a l k a l i n e s o l u t i o n s . I t i s the opinion of Thachter t h a t f a i l u r e to use a diaphragm has been the cause of much t r o u b l e . A s i x t h means of checking o x i d a t i o n i s to keep the c u r r e n t d e n s i t y below one ampere per. s q . dm.,--i.e. by the use of l a r g e anodes. E l e c t r o d e s i n the form of c o n c e n t r i c c y l i n d e r s permit the most even d i s t r i b u t i o n of current and prevent most completely excessive o x i d a t i o n which would r e s u l t from the p i l i n g up of c u r r e n t on c e r t a i n p a r t s of the e l e c t r o d e s . The l a r g e r the anode, the l e s s oxygen escapes as molecular oxygen, and hence the g r e a t e r the e f f i c i e n c y when usi n g l a r g e c u r r e n t s . The l a r g e anode permits a g r e a t e r q u a n t i t y of d e p o l a r i z e r to be i n contact w i t h the evolved anodic oxygen. The g r e a t e r the c o n c e n t r a t i o n of d e p o l a r i z e r , ( u p to a c e r t a i n p o i n t ) , the greater i s the current d e n s i t y which can be used without e v o l u t i o n of gas. 1. D i s c u s s i o n Trans. Am. Electrochem. S o c , 45, p 104, (1924). 16. The weaker the d e p o l a r i z e r , (not only as regards c o n c e n t r a t i o n , "but a l s o as regards i t s reducing p r o p e r t i e s ) , the l e s s nust be the cu r r e n t d e n s i t y . Current c o n c e n t r a t i o n , i.e. ampers per. l i t r e of s o l u t i o n , a l s o p l a y s an important r6\le. A seventh means of changing or r e g u l a t i n g the products of a l t e r n a t i n g c u r r e n t e l e c t r o l y s i s has been suggested. 1 This i s the s e l e c t i o n of the most s u i t a b l e power f a c t o r . The f a c t that the appearance of c e r t a i n l i n e s i n an arc spectrum depended upon the r e l a t i o n of c a p a c i t y and i n d u c t i o n i n the c i r c u i t , I.e., whether or not the E.M.F. was i n step w i t h the c u r r e n t , l e d Patten to the c o n c l u s i o n t h a t the percentage of a l t e r n a t i n g c u r r e n t a v a i l a b l e f o r doing work may i n f l u e n c e the products formed. Other f a c t o r s which i n f l u e n c e the nature and course of e l e c t r o l y s i s in g e n e r a l , and which should be considered i n t h i s research are s t i r r i n g , temperature* e t c . Brockman and others c o n s i d e r s t i r r i n g an absolute n e c e s s i t y f o r the successful p r o s e c u t i o n of an e l e c t r o l y s i s . In cases where an emulsion of the d e p o l a r i z e r i s maintained, t h i s f a c t o r i s a u t o m a t i c a l l y attended t o . But even where the d e p o l a r i z e r i s in t r u e s o l u t i o n the r a t e of e l e c t r o l y t i c r e a c t i o n is u s u a l l y g r e a t e r than the rat e of d i f f u s i o n . Hence, unless f r e s h q u a n t i t i e s of the d e p o l a r i z e r are mechanically c i r c u l a t e d to the anode s u r f a c e , e i t h e r 1. Trans. Am. E l e c t rochem. S o c , 29, 313, (1916). 17. excessive o x i d a t i o n w i t h l o s s of m a t e r i a l or undesired e v o l u t i o n of oxygen w i t h decrease i n current e f f i c i e n c y w i l l take p l a c e . Temperature must be regu l a t e d i f too vigorous o x i d a t i o n i s to be prevented. For each o x i d a t i o n r e a c t i o n there i s an optimum c o n c e n t r a t i o n of d e p o l a r i z e r f o r each value of cu r r e n t d e n s i t y and c o n c e n t r a t i o n . Another p o i n t to be considered i s tha t excessive and undesired decomposition of the organic s t a r t i n g m a t e r i a l may be due t o the formation of intermediate p e r o x i d e s . 1 I f f a c t o r s which discourage or prevent the formation of peroxides, can be di s c o v e r e d , i t may be p o s s i b l e to exclude peroxides from the s o l u t i o n thereby to c o n t r o l the extent of o x i d a t i o n . Such f a c t o r s as these have yet to be di s c o v e r e d . p I t has been shown by B i r c h e r and Harkins and others t h a t overvoltage increases w i t h decrease i n pressure. I t might be expected, then that by using l a r g e pressures, the overvoltage might be reduced to the extent that the degree of o x i d a t i o n c o u l d be c o n t r o l l e d . However, the e f f e c t of pressure i s most e f f e c t i v e at low pressures and Newbery ^ has shown th a t w i t h oxygen the overvoltage i s p r a c t i c a l l y constant over a range of 1-10.0 atmospheres. 1. Trans. Am. Slectrochem. S o c , 45, 154 (1924). 2. J . Am. Chem. S o c , 45, 2890 (1923). 3. J . Chem. S o c , 105, 2419, (1914). 18. C e r t a i n groups (such as the methyl group), when present as a s u h s t i t u e n t i n the benzene nucleus are known to d i r e c t new groups towards the para (and ortho) p o s i t i o n . E l e c t r o l y t i c i n t r o d u c t i o n of a s i n g l e h y d r o x y l group could be e f f e c t e d , probably more e a s i l y i n t o a compound w i t h some such s u b s t i t u e n t than i n t o benzene i t s e l f . I f t h i s s u b s t i t u e n t could be removed then, phenol would remain. T h i s , however, does not appear to be a very u s e f u l method. When T o n o l i 1 o x i d i z e d benzene sulphonic a c i d w i t h a very h i g h c u r r e n t d e n s i t y at a platinum anode, he obtained phenol and s u l p h u r i c a c i d . In F i c h t e r ' s report of t h i s experiment 2 the value given f o r the current d e n s i t y used i s 5 amps, per sq. cm. This seems exceedingly h i g h , being 500 amps per sq. dm. Stocker found that using lead peroxide anodes and .04 amps per sq. cm. the same compound y i e l d e d no phenol. I t appears then that there i s a p o s s i b i l i t y of o b t a i n i n g phenol e l e c t r o l y t i c a l l y and perhaps on a commercial s c a l e , from benzene. I f the process were c a r r i e d on near a s u l p h u r i c a c i d p l a n t , the e l e c t r o l y t i c process would be cheapest. Benzene could be t r e a t e d w i t h oleum; the r e s u l t i n g s o l u t i o n of benzene sulphonic a c i d d i l u t e d would be the anolyte from which phenol and s u l p h u r i c a c i d would be produced. A f t e r 1. Rend. Soc. Chim. I t a l . Fasca 2 (1912). 2. Trans. Am. Electrochem. S o c , 45, p 153. (1924). 19. removal of the phenol, the r e s u l t i n g s u l p h u r i c a c i d could he used to d i l u t e oleum, the mixture being pure enough, probably, f o r making f e r t i l i z e r s . E l e c t r o c h e m i c a l p r o d u c t i o n of compounds has the advantage 1 that mere o x i d a t i o n i s accomplished more economically by e l e c t r o l y s i s than by other chemical means and t h a t the absence of intermediate o x i d i z i n g r eactants avoids expense and contamination of the products. As noted by U e r n s t , 2 the proper c o n t r o l of e l e c t r o d e p o t e n t i a l permits a wide range of gas "pressures" at the e l e c t r o d e s u r f a c e . F u r t h e r , most chemical o x i d a t i o n of the aromatic nucleus i f e f f e c t e d , r e s u l t s i n d i s r u p t i o n of the r i n g w h i l e e l e c t r o c h e m i c a l o x i d a t i o n introduces a hydroxy1 group without breaking the r i n g . On the other hand, disadvantages which inhere i n e l e c t r o c h e m i c a l methods must not be overlooked. E l e c t r o l y t i c methods r e q u i r e more room, hence l a r g e r and more e x p e n s i v e p l a n t s , and demand more s k i l l e d a t t e n t i o n and greater upkeep cost than o r d i n a r y chemical p l a n t s . F u r t h e r , the need of g r e a t e r amount of time, thought and expenditure i n the working out of the e l e c t r o l y t i c methods and the p r e p a r a t i o n of the process f o r l a r g e s c a l e production must be a n t i c i p a t e d . Most of the d i f f i c u l t i e s encountered at f i r s t , i n v o l v i n g diaphragms, have been overcome, as f a r 1. Trans. Am. Electrochem. S o c , 3_6, 337 (1919). 2. B e r . p 1562 (1897). 2 0 . as a c i d and n e u t r a l s o l u t i o n s are concerned, "by the use of " E l e c t r o - P i l t r o s , " 1 devised "by Thachter and i n use s i n c e 1915. 1. Met. & Chem. Eng. (1915). 13, 336-38. 21. I I . Previous Work. A search of the a v a i l a b l e l i t e r a t u r e has revealed no i n d i c a t i o n of any work having been done on the e l e c t r o l y s i s of benzene i n concentrated a c e t i c a c i d s o l u t i o n , Segewetz and Miodon 1 used 33% a c e t i c a c i d w i t h 25% s u l p h u r i c a c i d as an e l e c t r o l y t e but even at t h i s c o n c e n t r a t i o n of a c i d the benzene was not s u f f i c i e n t l y s o l u b l e to make an emulsion unnecessary. Only one case has been found where e l e c t r o l y s i s of benzene has y i e l d e d phenol and here nothing more than a rough q u a n t i t a t i v e estimate i s g i v e n . P r a c t i c a l l y nothing has been reported on the use of non-aqueous s o l u t i o n s f o r e l e c t r o l y t i c o x i d a t i o n s . A c e t i c a c i d of the c o n c e n t r a t i o n used i s i n a l i m i t e d sense, a non-aqueous e l e c t r o l y t e , f o r without a d d i t i o n of sodium hydroxide, the conduction of current i s n e g l i g i b l e . Undoubtedly the c u r r e n t i s conducted by the Na +and 0H~ ions which would not e x i s t i f there were not some water present, yet i t i s by reason of the l a r g e concentration of u n d i s s o c i a t e d a c e t i c a c i d that the d e p o l a r i z e r i s h e l d i n t r u e s o l u t i o n . A Hew Emphasis as t o The Mechanism of E l e c t r o - o x i d a t i o n . I t has been noted i n the i n t r o d u c t i o n that benzene can be o x i d i z e d to phenol by the use of hydrogen peroxide, e t c . as w e l l as by anodic oxygen. In g e n e r a l , anodic o x i d a t i o n y i e l d s the same, products as do hydrogen peroxide, ozone and p e r s u l p h u r i o a c i d . This f a c t has l e d some 1 . B u l l . Soc. Chim., (17) 33_, 449 (1923). 22. organic e l e c t r o c h e m i s t s to the c o n c u l s i o n or b e l i e f that such e l e c t r o - o x i d a t i o n i n v o l v e s the formation of a peroxide of some s o r t at the anode. 1 Hence the p o p u l a r i t y of s u l p h u r i c a c i d as an e l e c t r o l y t e f o r o x i d a t i o n . But O F i c h t e r has shown that products a t t r i b u t e d to the formation of p e r s u l p h u r i c a c i d e t c . at the anode, can be obtained a l s o i n phosphoric a c i d s o l u t i o n s under c o n d i t i o n s i n which p e r a c i d s do not form. Though the peroxide formation hypothesis has many advantages over other hypothesis, and may apply i n some cases, I b e l i e v e the emphasis has been put i n the wrong p l a c e . Instead of c o n s i d e r i n g the o x i d a t i o n to proceed as a r e s u l t of the formation of a peroxide, p l a c i n g the emphasis of the s i m i l a r i t y of mechanism on the peroxide - i t seems to me, b e t t e r to consider the o x i d a t i o n a r e s u l t of "nascent" or monatomic oxygen which forms supposedly, both at the anode and i n the decomposition of the peroxides and thereby p l a c i n g the emphasis of s i m i l a r i t y of mechanism on the format ion of the "nascent" oxygen. I have no r e c o l l e c t ion of having heard of , or of having seen i n p r i n t , the emphasis so plac ed,-- though be i t granted the idea that atomic oxygen i s necessary i n both cases i s o l d . But i t seems that the resemblance between the chemical o x i d a t i o n of peroxides and the e l e c t r i c a l 1. F i c h t e r , Trans. Am. Electrochem.Soc., 45, 0 131 (1924). 2. I b i d . 45-, p 111. 23. o x i d a t i o n i s due not to the presence of peroxides i n "both eases, hut r a t h e r to monatomic oxygen. Instead of e x p l a i n i n g e l e c t r o l y t i c o x i d a t i o n i n terms of peroxides we can e x p l a i n the mechanism of o x i d a t i o n of peroxides i n terms of o x i d a t i o n by s i n g l e molecules of oxygen as may w e l l be the case i n anodic o x i d a t i o n . x h i s does away w i t h the n e c e s s i t y of hunting f o r peroxides i n e l e c t r o l y t e s which seem incapable of producing them. 24. H I E x p e r i m e n t a l ,  Method: E l e c t r o d e s of n i c k e l , platinum, copper and i r o n were used i n s o l u t i o n s a l k a l i n e w i t h sodium hydroxide or a c i d w i t h s u l p h u r i c a c i d or a c e t i c a c i d * In a l l cases where concentrated a c i d was not used, the emulsion of benzene was maintained by use of a s t i r r e r . Q u a l i t a t i v e t e s t s f o r phenol were made w i t h samples taken from time to time, from the e l e c t r o l y t e . Q u a l i t a t i v e tests f o r phenol were made w i t h the v a r i o u s t e s t s recorded i n the l i t e r a t u r e . These are t o be des c r i b e d i n d e t a i l l a t e r . Q u a n t i t a t i v e t e s t s or determinations of the pehnol content of the r e a c t i o n products were made only a f t e r s e p a r a t i n g phenol from the other o x i d a t i o n products. In cases where concentrated a c a t i c a c i d was used, t o 40cc. of the g l a c i a l a c i d were added 5 c c . of concentrated sodium hydroxide s o l u t i o n . The d e s i r e d amount of benzene when added to t h i s d i s s o l v e d r e a d i l y . C y l i n d r i c a l anodes, - - u s u a l l y of wire gauze, were used. When d e s i r e d , i r o n or copper was e l e c t r o p l a t e d p r e v i o u s l y , onto the anode. In some cases a diaphragm was used. This was a porous cup, made of unglazed p o r c e l a i n , and ju s t l a r g e enough to co n t a i n the anode. When l a r g e c u r r e n t s were used, the c e l l was p l a c e d i n c o l d running water to prevent v o l a t i l i z a t i o n of benzene e t c , by the h i g h temperature. The diagram of the c e l l i s found i n F i g u r e 1. |jo>-ous cuj? Anode Benzene I F i g u r e 1, 25. The e l e c t r i c a l hook-up i s shown i n F i g u r e 2 and 3. In F i g u r e 2, the ohmic r e s i s t a n c e ( % ) , i n the AC c i r c u i t i s made so l a r g e i n comparison w i t h the r e s i s t a n c e of the o e l l t h a t most of the d i r e c t c u r r e n t flows through the c e l l and r e l a t i v e l y l i t t l e through the secondary c o i l of the transformer. Obviously a h i g h E.M.F. from the AC source must be used to overcome t h i s non-inductive r e s i s t a n c e . A choke having l i t t l e ohmic r e s i s t a n c e but a l l o w i n g very l i t t l e f l o w of a l t e r n a t i n g current was placed i n the D.C. c i r c u i t to keep the AC f l o w i n g through the c e l l r a t h e r than through the b a t t e r i e s or motor generator. In F i g u r e 3 the DC i s passed through the sec ondary c o i l of the transformer. The ammeters and voltmeters are l e f t i n c i r c u i t or i n p a r a l l e l f o r only an i n s t a n t a t a time. As the AC volt a g e across the c e l l was s m a l l , and as the d e v i s i o n s on the AC instruments vary as the square of the current i n v o l v e d , some d i f f i c u l t y was experienced i n o b t a i n i n g an accurate measure of the a l t e r n a t i n g PD. However, t h i s was overcome by measuring the PD between the extreme t e r m i n a l s of the c e l l and of a non i n d u c t i v e r e s i s t a n c e i n s e r i e s w i t h the c e l l ; and then across the r e s i s t a n c e alone. The PD across A*C l e s s that across B-C equals the PD across the ele c t r o d e s A-B. Q u a l i t a t i v e t e s t s f o r phenol were made f i r s t w i t h bromine water. The f r e e a c i d was n e u t r a l i z e d w i t h sodium hydroxide and the s o l u t i o n made j u s t a c i d w i t h h y d r o c h l o r i c 26. a c i d . A d d i t i o n of bromine water gave a y e l l o w p r e c i p i t a t e of t e t r a brom-phenol when phenol was present. J i l l Ion's Reagent, i n the presence of anything g r e a t e r than 1 p a r t of phenol i n 2,000,000. gave a red c o l o r a t i o n on standing or immediately a f t e r h e a t i n g . The pres-ence of acetate ion hindered t h i s t e s t and made the red c o l o r a t i o n very t r a n s i e n t . The reagent was prepared accor d i n g to d i r e c t i o n s of Elvove 1 as reported by H. D. G i b b s . 2 68g of mercury d i s s o l v e d i n 50 cc. of concentrated n i t r i c a c i d give 40 c c . of s o l u t i o n to which 92 c c . of water are added. N i t r i c a c i d i s added i f a p r e c i p i t a t e r e s u l t s and u n t i l s o l u t i o n becomes c l e a r . An e q u a l l y d e l i c a t e t e s t i s reported by Eykman. 3 A few drops of a l c o h o l i c s o l u t i o n of e t h y l n i t r i t e added to phenol s o l u t i o n gave a red c o l o r a t i o n a f t e r adding an equal volume of s u l p h u r i c a c i d . The t e s t was found to give good r e s u l t s when a l c o h o l , sodium n i t r i t e and s u l p h u r i c a c i d were used. There i s a s i m i l a r t e s t w i t h isoamyl n i t i r i t e . Isoamyl c h l o r i d e was used w i t h s a t i s f a c t o r y r e s u l t s , — t h e c h l o r i d e being converted to the n i t r i t e as soon as the sodium n i t r i t e was added. 1 c c . of phenol s o l u t i o n w i t h 2 cc . of concentrated s u l p h u r i c a c i d heated w i t h 2 drops of benzaldehyde gave I. B u l l Hyg. Lab. U. S. P. A. 1917 cx 25. 2. J , B i o l . Chem. 71. 450. 3. New Remedies 1882 X I 340* 27. a y e l l o w to red c o l o r a t i o n which turned to blue when d i l u t e d and made a l k a l i n e w i t h potassium hydroxide. A few drops of s o l u t i o n of hypochlorous a c i d , UaOCl or hypobromous a c i d , or KaOBr or c h l o r i d e of l i m e , added to phenol s o l u t i o n w i t h excess ammonia gave a l i g h t blue c o l o r a t i o n . L a c t i c a c i d and p y r u v i c a c i d used w i t h s u l p h u r i c a c i d each gave the c h a r a c t e r i s t i c c o l o r a t i o n w i t h phenol. D i s t i n c t i o n from the p o l y h y d r i c phenols was made by the use of s i l v e r n i t r a t e . The substance t e s t e d d i d not reduce s i l v e r n i t r a t e as do the p o l y h y d r i c phenols. This f a c t , together w i t h p o s i t i v e r e s u l t s obtained w i t h a l l of the above t e s t s , i n d i c a t e s q u i t e d e f i n i t e l y , that phenol i s present i n the r e a c t i o n product. Q u a n t i t a t i v e measurement of phenol content was made as f o l l o w s ; - - F i r s t the r e a c t i o n products were made a l k a l i n e w i t h sodium h y d r o x i d e ; — t h e n j u s t a c i d w i t h h y d r o c h l o r i c (presence of even s m a l l amounts of a c e t i c a c i d i n t e r f e r e w i t h the t e s t ) . The mixture was steam d i s t i l l e d . 150 cc of d i s t i l l a t e were c o l l e c t e d , or more, u n t i l the d i s t i l l a t e showed only very s l i g h t t r aces of phenol* The d i s t i l l a t e was d i l u t e d w i t h d i s t i l l e d water to 250 cc. and thoroughly mixed. The odor of phenol was q u i t e obvious. A standard s o l u t i o n of phenol c o n t a i n i n g ,0002344g. per c c . was prepared. Equal volumes of t h i s and the s o l u t i o n of unknown were placed i n small home made comparison tubes and to these, equal volumes of bromine 28. water were added. D i s t i l l e d water was added to the one which was most cloudy u n t i l the two were e q u a l l y cloudy. This comparison, made Toy l o o k i n g through the tubes i n t o d i f f u s e l i g h t , gave accurate r e s u l t s provided the t e s t was made s p e e d i l y , i . e . before c o a g u l a t i o n of the p r e c i p i t a t e took p l a c e . Prom the volume of l i q u i d i n each tube, the c o n c e n t r a t i o n of phenol i n the unknown s o l u t i o n could be c a l c u l a t e d from the known c o n c e n t r a t i o n of the standard. Steam d i s t i l l a t i o n of the r e a c t i o n mixture provided the only s u c c e s s f u l means of s e p a r a t i n g phenol from the other products. P r e f e r e n t i a l a dsorption of phenol on cha r c o a l was t r i e d , but the c o n c e n t r a t i o n of phenol was so low th a t the scheme d i d not meet w i t h success. In some experiments a r e c t i f i e d c u r r e n t was used. A tantalum metal e l e c t r o d e was the r e c t i f i e r . A small sheet of tantalum was placed i n the c e l l and 90 v o l t s DC were a p p l i e d f o r 2 hours. The l a r g e f a l l of p o t e n t i a l at the s u r f a c e of the r e c t i f i e r caused sparking at the e l e c t r o d e . A f t e r 2 hours only .o4 amperes were f l o w i n g . The tantalum became covered w i t h a blue d e p o s i t . A PD of 9 v o l t s was a p p l i e d f o r 18 hours, a f t e r which time no current was f l o w i n g which was l a r g e enough to be measured on the ammeter. This e l e c t r o d e was then used as a r e c t i f i e r . The c e l l was placed i n an AC c i r c u i t taken from a transformer. 15.2 v o l t s AC gave a current which measured 60 milliamperes. 29 . on a DC milliarometer. In some experiments the d i r e c t i o n of fl o w of current was reversed i n the middle of the e l e c t r o l y s i s i n the hope th a t o x i d a t i o n of r e d u c t i o n products might y i e l d some compounds d i f f e r e n t from those obtained by o x i d a t i o n of the o r i g i n a l r e a c t a n t . These experiments i n v o l v e d the use of a number of d i f f e r e n t types of c u r r e n t . I f the or d i n a r y d i r e c t c u r r e n t be represented by (a) i n Figure 4. the o r d i n a t e i n d i c a t i n g the extent of the charge on the e l e c t r o d e and the a b s c i s s a i n d i c a t i n g time, then (b) represents the nature of the current when current i s reversed. The a l t e r n a t i n g current used by i t s e l f i s represented by ( c ) , and when used superimposed upon d i r e c t c u r r e n t , by (d) and ( e ) . That obtained w i t h the tantalum e l e c t r o d e i s represented by ( f ) . The decomposition p o t e n t i a l i n d i c a t e d by the red l i n e s need not n e c e s s a r i l y have the same value above as below the l i n e of zero v o l t a g e (green). The a c t u a l value f o r the decomposition p o t e n t i a l was not obtained. Attempts were made to measure i t i n a s o l u t i o n of 50 c c . of benzene i n 100 cc. of a c e t i c a c i d , but there was no sudden change of slope of the vo l t a g e - c u r r e n t graph, as can be seen by the r e s u l t s recorded i n the next s e c t i o n ; hence there seemed to be no p a r t i c u l a r value f o r the decomposition p o t e n t i a l over the range s t u d i e d . CURRENT GRAPHS ( a ) S i m p l e D i r e c t C u r r e n t . (b) D i r e c t C u r r e n t R e v e r s e d . ( c ) S i m p l e A l t e r n a t i n g C u r r e n t . (d) A l t e r n a t i n g c u r r e n t s u p e r i m p o s e d on D i r e c t . (e ) A l t e r n a t i n g c u r r e n t s u p e r i m p o s e d on a l a r g e r D i r e c t C u r r e n t , G r e e n L i n e s ; - - Z e r o v o l t a g e . Red L i n e s ; - - D e c o m p o s i t i o n p o t e n t i a l s , B l a c k l i n e s ; - - V a r i a t i o n o f c h a r g e on O r d i n a t e s ; - - V o l t a g e o r c h a r g e . A b s c i s s a e ; - - T i m e . ( f ) I n t e r m i t t e n t c u r r e n t o b t a i n e d w i t h t h e T a n t a l u m e l e c t r o d e s . e l e c t r o d e s o r v o l t a g e . F i g u r e 4 30. IT. R e s u l t s . The c u r r e n t - v o l t a g e curve f o r a s o l u t i o n of 50 cc. benzene i n 100 c c . a c e t i c a c i d i s given i n Graph I . Where a l c o h o l i s s u b s t i t u t e d f o r acetic a c i d , the r e s u l t s shown by Graph I I , a c i d ( w i t h HC1) s o l u t i o n and by Graph I I I , b a s i c ( w i t h NaOH) s o l u t i o n , are obtained. In the case of the l a s t two graphs there seems to be a decomposition at about 1.6 v o l t s but w i t h benzene i n a c e t i c a c i d the curve i s q u i t e smooth. The only other products examined c l o s e l y were those obtained from experiments 1, 2, and 17. A f t e r the products from Experiment 2 had stood f o r some time (about 2 months), many c r y s t a l s separated out. These were separated from the mother l i q u o r and washed w i t h ether, i n which they are i n s o l u b l e , d r i e d between towels and d e s i c c a t e d over anhydrous cal c i u m c h l o r i d e f o r two weeks. Pour samples were weighed out i n t o d e s i c c a t e d , weighed c r u c i b l e s . A f t e r heating f o r 12 hours at 104°C. they were reweighed and again a f t e r 1 hour at 150°C. A l l f o u r weights check c l o s e l y w i t h what i s to be expected from the decomposition of sodium acetate w i t h two moltecules of a c e t i c a c i d of c r y s t a l l i z a t i o n to the ordinary anhydrous sodium a c e t a t e . Treatment w i t h excess h y d r o c h l o r i c a c i d f o l l o w e d by d r y i n g and reweighing gave a r e s u l t which checked c l o s e l y w i t h that expected from the conversion of sodium acetate to sodium c h l o r i d e . The c r y s t a l s d i s s o l v e d - 4 - , I i I6* <5R u 31. r e a d i l y i n water g i v i n g an a c i d s o l u t i o n . Sodium hydroxide s o l u t i o n was standardized and used to t i t r a t e a known weight of the c r y s t a l s . Prom the normality of the s o l u t i o n and the volume used, the t i t r a t i o n equivalent was found,to he 101.6. Prom t h i s data i t was evident that the c r y s t a l l i n e substance was CH3C00Ha."CH3C00H. This substance has been recognised f o r some time, and of course, i s not a product of e l e c t r o l y s i s . But c r y s t a l s obtained i n a s i m i l a r manner from Experiment 1. f a i l e d to correspond t o any p r e v i o u s l y recognized compound. These c r y s t a l s , were, l i k e those of Experiment 2, i n s o l u b l e i n ether, carbon t e t r a c h l o r i d e , only s l i g h t l y s o l u b l e i n 95% e t h y l a l c o h o l , but very s o l u b l e i n water. T h e i r aqueous, s o l u t i o n was a c i d . However, t i t r a t i o n showed an e q u i v a l e n t weight of 151. Obviously t h i s i s not the same compound as was obtained i n Experiment 2 though both compounds have much i n common. Both gave o f f , on heating* an inflammable gas, (acetone i n the case of Experiment 2 ) , and l e f t a residue of sodium carbonate. A d d i t i o n of concentrated s u l p h u r i c a c i d to f r e s h c r y s t a l s l i b e r a t e d an a c i d which, i n s m e l l , resembled c l o s e l y , a c e t i c a c i d . Hence the compound i n question appears to be the sodium s a l t of an organic a c i d together ?*rith a c e t i c a c i d of c r y s t a l l i z a t i o n . When the c r y s t a l s are heated g e n t l y , i t seems that the acetate r a d i c a l u n i t e s w i t h the sodium ion g i v i n g sodium acetate ^ — e x c e s s a c i d s being d r i v e n o f f . The 32. residue melts a t 312°C as does sodium acetate. Vacuum d i s t i l l a t i o n of these c r y s t a l s together w i t h s u l p h u r i c a c i d , y i e l d e d a t r a c e of l i q u i d which had the smell of a c e t i c a c i d , but unmistakably, a l s o that of v a n i l l a . Just how v a n i l l i n was formed from benzene, i s u n c e r t a i n , but i t i s p o s s i b l e that isoeugenol was an intermediate product as v a n i l l i n has been obtained from isoeugenol e l e c t r o l y t i c a l l y , ^ The m e l t i n g p o i n t of the c r y s t a l s was tl-94°C and decomposition took p l a c e at 160-162°C. The unknown organic a c i d r a d i c a l of t h i s compound may be the same as that obtained i n a d i f f e r e n t manner i n Experiment 17. A f t e r a l l the a c i d has been n e u t r a l i z e d w i t h sodium hydroxide and the phenol had been steam d i s t i l l e d the r e sidue was allowed to c o o l . C r y s t a l s 8 x 1 x 1 cm* formed. These t r e a t e d i n a manner s i m i l a r to the treatment described above f o r c r y s t a l s from Experiment 2, proved to be something other than pure hydrated sodium a c e t a t e , though both sodium and acetate r a d i c a l s were involved i n the make up of t h i s c r y s t a l l i n e substance. The y i e l d s of phenol and the c o n d i t i o n s under which they were obtained i n the v a r i o u s experiments are i n d i c a t e d i n the f o l l o w i n g t a b l e . 1. D. R. P. 92007 (1895). and see a l s o Trans Am. Electrochem. S o c , 42, 273, (1922). 33. D C . D i a - .VoltsjampsjVoltsjAmpg;Timento 6 6 2 2 2 2 2.6 .05 .07 .0192 .019J2 .02 .05 1.3 13 7.4 2.5 n 12 12 1.44 1.4 2. it it ii it . 0 1 6 .07 • OOSJ .06 A C . .12 3 15. 9 10 .07 -10 houragm. 2 N i . R No DLL. NaOH i¥ i * ' 2 " 44 d 9 » 24" 30" 48" 28Pt 36" II » II II II «» II II S" lu "" II II II II ti II II w n n V o l V o l . of enzHOAc ene. no AIC - H 2 S O 4 HOAc Olac 1 "yes " - l l d a y s N i " " -7 daysCu" " l l d a y s "" " 2 daysTa&pt* 5days nichr"" 3days Cu nd' 4 " 2 " i - • 3 i " 3 " II ! II 25 50 II 50 100 s l i g l r , •» II qual No ti II s l i g h t 11 II q u a l i t more 11 II .08% 11 II no 20 40 qual 20 40 s l i g h t 11 11 qjaal s l i g h t tt II s l i ^ht no 11 11 qual Pt II I" II II II II I Pt&Pe»'» " Cu " " " " 11 « 11 s l i g h t qual 1 1 % .00 .00 .29% .12% 50 100 100 34. No.olf D Exp 18. 19. 20. 21&; 23. 24. 25. 28. 29. 30. 31. 32. 33. 34. 35. 2 2 4 30&ufc 40&u > 15-40 10-30 15-30 19-40 19- 4<|> 20 15-20 20- 20- 2t C Amps VoltsAmpsTimeAnodephr 2$ i.e 1. A.C. hours piaH 5i» l | " 2 i w 1 M 3dayjs Cu 24ho|ur " 8 " it II Pt i i n l i i " i " i f " i f " i£" Cu Pt y e s it T electroly tephenolBen zen HOAo HOAc Qiao > . 22%j .00 .00 yes c c . o f II II Jome CuS04 ess n HOAo Glac ti it ti it with CttSO with aftm. meta vanadate .50% 1.17% 1.76% 1.56% 1.5% 1.17% 1.0% 1. 1.76% 1.5% 20 10 5 5 3 3 3 5 5 5 c c . o f 40 35. V. D i s c u s s i o n of R e s u l t s . As can "be seen from the r e s u l t s , the superimposition of a l t e r n a t i n g c u r r e n t on d i r e c t current does not seem to increase the y i e l d of phenol. F u r t h e r , the higher the v o l t a g e used, ( w i t h i n reasonable l i m i t s ) , the more phenol i s obtained. This corresponds to the f i n d i n g s of Stocker and T o n o l i when they e l e c t r o l i z e d benzene sulphonic a c i d . ^~ I t w i l l be noted t o o * that the presence of a small quantity of the s a l t s of copper, i r o n or vanadium increases the y i e l d of phenol, but that a l a r g e q u a n t i t y of any of these s a l t s ( e s p e c i a l l y of the f i r s t two), causes excess o x i d a t i o n . 1. Rend Soc. Chim. I t a l . Fasca. 2 (1912). s 36. V I . Summary. 1. A f a i r l y d e t a i l e d summation of the f a c t o r s which i n f l u e n c e e l e c t r o l y s e s such as t h i s one» has been made • 2. Phenol has been obtained e l e c t r o l y t i c a l l y from benzene; the highest y i e l d , however, was 1.76%. 3. This has, together w i t h the r e s u l t s of F i c h t e r and Uhl r e f e r r e d to on page 2, provided evidence f a v o r i n g the p r e d i c t i e n of s e v e r a l organic e l e c t r o c h e m i s t B t h a t phenol i s the f i r s t e l e c t r o - o x i d a t i o n product of benzene. 4. In these experiments, the saperiraposition of A l t e r n a t i n g Current d i d not inc r e a s e the y i e l d of phenol. 5. The presence i n the e l e c t r o l y t e , of sm a l l q u a n t i t i e s of s a l t s of m u l t i v a l e n t metals i s b e n e f i c i a l . 6. A h i g h v o l t a g e i s p r e f e r a b l e to a low voltage i f phenol i s d e s i r e d . 7. E l e c t r o l y s i s of benzene produces an e q u i l i b r i u m mixture of phenol w i t h other products. The concentration of phenol was probably never more than 2% of the o r i g i n a l c o n c e n t r a t i o n of benzene. 37. In c o n c l u s i o n I wish to express my thanks to Dr. R. H. C l a r k f o r k i n d l y c r i t i c i s m and the many h e l p f u l suggestions o f f e r e d throughout these i n v e s t i g a t i o n s . 38 V I I . B i b l i o g r a p h y . B. THE EFFECT OF CERTAIN CHEMICALS ON THE HTOROLTTIC ACTIVITY OF RICINUS AND PORK PANCREAS LIPASE. 39, THE EFFECT OP CERTAIN CHEMICALS ON THE HYDROLYTIC ACTIVITY OP RICINUS AND PORK PANCREAS LIPASE. F o l l o w i n g up the work done i n these l a b o r a t o r i e s on the a c t i v a t i o n of amylase, experiments were c a r r i e d out to d i s c o v e r the i n f l u e n c e of c e r t a i n chemicals, e s p e c i a l l y organic chemicals, on the h y d r o l y t i c a c t i v i t y of l i p a s e . 1 C e r t a i n chemicals have been found capable of shortening the dormant p e r i o d of seeds. The above mentioned work has shown t h a t t h i s may be due t o the a c t i v a t i o n of amylase i n the seed, r e s u l t i n g i n the production of a hexose which serves as a source of food f o r the growing embryo. In the case of c e r t a i n seeds, i t may be t h a t the dormant p e r i o d may be broken prematurely, by the use of c e r t a i n chemicals which a c t i v a t e l i p a s e . L ipase i s known to be present i n an a c t i v e form i n germinating endosperms of o i l y seeds, but not i n the r e s t i n g seeds. Furthermore, l i p a s e occurs i n many d i f f e r e n t forms w i t h i n the animal body. Serious cases of t u b e r c u l o s i s are u s u a l l y accompanied by low values of serum l i p a s e . The l i p a s e i n h i b i t s the growth of the t u b e r c l e b a c i l l u s by d e s t r o y i n g the waxy or f a t t y covering which i s c h a r a c t e r i s t i c of Mycobacterium t u b e r c u l o s i s . I f an a c t i v a t o r f o r serum l i p a s e could be found, i n j e c t i o n of t h i s a c t i v a t o r , i n t o the blood stream, might r e s u l t i n 1. Trans. Roy. Soc. Canada; XXV Sect I I I , 99 (1931). 40. h e l p i n g the body to win the b a t t l e against the t u b e r c l e b a c i l l u s . Previous Work; Much work has already been done along t h i s l i n e . The r e s u l t s are very c o n f l i c t i n g . Palmer 1 r e p o r t s that w i t h commercial l i p a s e (source not s t a t e d ) , formaldehyde i n conce n t r a t i o n s between 1 part i n 1000 and 1 pa r t i n 1500 gave a 16% increase i n a c t i v i t y . Mercuric c h l o r i d e i n conc e n t r a t i o n s .1 to .3% Completely i n h i b i t e d the h y d r o l y s i s . Acetone .6% to 12% i n h i b i t s by 11%-24%. Iodine .09% reta r d s the r a t e 96% and Bromine .25% r e t a r d s a c t i v i t y by 93.2% Hy d r o c h l o r i c a c i d has been reported as an a c t i v a t o r . Enzymes Used. In these s t u d i e s , two l i p a s e s were used. One was animal i n source. This was s u p p l i e d by Eimer & Amend. I t was prepared from pork pancreas. The pancreas was vacuum d r i e d at a low temperature, and d e f a t t e d w i t h benzol. Benzol was removed i n vacuo. The product was then powdered and s i f t e d . The other l i p a s e was a p l a n t l i p a s e . Castor o i l beans, ( R i c i n u s Zanzibariensis., mixed), were germinated by keeping the seeds i n a moist c o n d i t i o n at 80°P f o r one week. The seeds were s h e l l e d by hand and the endosperms were c o a r s e l y ground and washed once w i t h ether. T&JES m a t e r i a l 1. Joura. Am. Chem. S o c , 44, 1527, (1922). 2. Journ. Am. Chem. S o c , 43, 2664, (1921). 41. was e x t r a c t e d i n a Soxhlet w i t h e t h y l ether f o r one week. The o i l f r e e m a t e r i a l was a i r d r i e d and then placed i n a vacuum d e s i c c a t o r over calcium c h l o r i d e f o r three weeks. This d r i e d product was powdered i n a mortar and passed through a 100 mesh s i e v e . P r e p a r a t i o n of Substrate. Gold drawn c a s t o r o i l was the substrate used. A suspension of the o i l was made w i t h gum a c a c i a . ,55grams of powdered gum a c a c i a was mixed thoroughly i n a mortar w i t h 90 c c . of c a s t o r o i l , t i l l an o i l y paste r e s u l t e d . Water was added i n 5 cc. q u a n t i t i e s w i t h thorough mixing between each a d d i t i o n . A f t e r about 100 cc of water has been addid, the mixture was d i l u t e d to 2500 c c . This g i v e s a s t a b l e emulsion of 3,2% o i l i n water. The emulsions prepared i n t h i s way were found to be much su p e r i o r t o those prepared according to d i r e c t i o n s i n the l i t e r a t u r e where the gum a c a c i a i s hydrated before a d d i t i o n of the o i l . Method, 75 c c . p o r t i o n s of t h i s c a s t o r o i l m i l k were placed i n 125 c c . Erlenmeyer f l a s k s . The f l a s k s were p r e v i o u s l y t r e a t e d to remove traces of d i - or m u l t i - v a l e n t s a l t s such as mercuric s a l t s , which might be on the surfaces of the g l a s s . 3 grams of l i p a s e were suspended i n 100 cc of t h i s " m i l k M and 3 c c . of the suspension was added to the 75 c c . p o r t i o n s of "milk". The chemicals were then added, except t o the c o n t r o l s 9 - - a n d a l l f l a s k s were incubated at 37°C. T i t r a t i o n s were made on 25 cc. p o r t i o n s from 24 to 42. 96 hours l a t e r , '•'•'he extent of h y d r o l y s i s was a s c e r t a i n e d by t i t r a t i o n of the f a t t y a c i d s produced,with .1 Normal sodium hydroxide s o l u t i o n , using a deep red of phenolphthalein as an end p o i n t . A b u r e t t e of s m a l l diameter permitted accurate readings of s m a l l volumes of sodium hydroxide s o l u t i o n . A l l t i t r a t i o n values were compared w i t h those obtained from (1) enzyme p l u s substrate without chemicals added, (2) s u b s t r a t e p l u s chemical without enzyme added, (3) s u b s t r a t e i n water without e i t h e r enzyme or chemical. R e s u l t s • Chemical and Concentration E f f e c t on R i c i n u s l i p a s e  E f f e c t on Pacreas l i p a s e  H y d r o c h l o r i c a c i d . .023% L a c t i c a c i d .2% Iodine aqueous .0019% decreases a c t i v i t y decreases a c t i v i t y markedly almost complete i n h i b i t i o n . almost complete i n h i b i t i o n . marked i n h i b i t i o n f o r f i r s t 24 hours f o l l o w e d by a 20% increase otwr c o n t r o l s a f t e r 96 hours. Bromine aqueous same a c t i o n as f o r i o d i n e . .125% Acetone 5% and down E t h y l b enzyl ketone i n h i b i t s 40% .2% I s o b u t y l c r e s o l ketone ,2% Methyl i s o b u t y l c r e s o l ketone ,2% i n h i b i t s 80% and down i n h i b i t s 60% down, i n h i b i t s 40% i n h i b i t s 5% and l e s s i n h i b i t s 5% and l e s s . E f f e c t s m a l l , seme- Sometimes a c c e l e r a t e s times a c c e l e r a t e s by 5%, by 5%. 43 Chemical and Concentration . Formaldehyde T e c h n i c a l . 1% Cinnamic aldehyde .005—.1% Hydrocinnamic aldehyde .002--.05% C r o t o n i c Aldehyde .002%—.05% A c r y l i c aldehyde .02% Acetaldehyde .02% Paraldehyde .02% Benzaldehyde . 1 % & l e s s F u r f u r a l .002%—.05% Iso "butyl Aldehyde .002%-.05% S a l i c y l i c aldehyde .002%-.05% Mercu r i c c h l o r i d e .01% .003% Potassium thiocyanate 1% f r e s h s o l u t i o n o l d s o l u t i o n f r e s h from d i f f e r e n t souree E f f e c t on R i c i n u s E f f e c t on Pancreas l i p a s e . l i p a s e .  i n h i b i t i o n 80% i n h i b i t i o n 30% marked decrease i n both cases. decrease decrease complete to 10% i n h i b i t i o n complete i n h i b i t i o n decrease decrease s l i g h t deciease s l i g h t decrease decrease decrease decrease decrease i n h i b i t s 95% 90% 120% increase decrease decrease decrease decrease decrease decrease 80% decrease decrease decrease. 44. Chemical and E f f e c t on R i c i n u s E f f e c t on Pancreas Concentration. l i p a s e l i p a s e .  Ethylene c h l o r - decrease decrease h y d r i n .3% Thiourea decrease decrease .15% C y s t e i n decrease decrease 1/15 cone of s a t . s o l u t i o n S k a t o l (Sat) decrease decrease 1—1/5 sat u r a t e d Pyridene .05%--.002% increase i n low co n c e n t r a t i o n s . A compound w i t h the formula H-U CsO i i C 2H 5- S-6 0 " ° % H C-H i n c o ncentrations of .02% gave decreases i n both cases. Conclusions. I t w i l l he observed, that as a whole aldehydes cause a decrease i n a c t i v i t y i n the concentrations used. Ketones l i k e w i s e appear to decrease the a c t i v i t y . The double bond i n an aldehyde seems to have an appreciable e f f e c t Potassium thiocyanate decreases the a c t i v i t y of animal l i p a s e , but sometimes increases the a c t i v i t y of R i c i n u s l i p a s e . This may be due to the a c t i o n of the K 4 ion r a t h e r than to the 8GM~ i o n . Old s o l u t i o n s seem to contain some decomposition product of KSC1 which i n h i b i t s a c t i v i t y . F u r t h e r , d i f f e r e n t samples of the m a t e r i a l have d i f f e r e n t e f f e c t s i n d i c a t i n g that the C P . m a t e r i a l contains v a r y i n g 45. q u a n t i t i e s of im p u r i t y . H y d r o c h l o r i c i n the concentrations found by Palmer to produce a c t i v a t i o n (not using an emulsion) d i d not cause an a c t i v a t i o n w i t h the suspension. L a c t i c a c i d i s considered by some ay that substance which converts the zymogen to l i p a s e i n p l a n t s ' seeds. However i n v i t r o almost complete i n h i b i t i o n r e s u l t s w i t h even reasonably s m a l l c o n c e n t r a t i d n s . The r e s u l t s obtained w i t h the f r e e halogens are very i n t e r e s t i n g . I t w i l l be observed that much l a r g e r q u a n t i t i e s of bromine are re q u i r e d to give the same e f f e c t as sm a l l q u a n t i t i e s of i o d i n e . 

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