W. A. Di*ushel — Hydrolysis of Esters in Fatty Acids. 27 



Art. III. — On the Hydrolysis of Esters of Substituted Fatty 

 Acids ; by W. A. Drushel. 



[Contribution from the Kent Chemical Laboratory of Yale Univ. — ccxxviii.] 

 2. Ethyl Cyanacetate. 



When hydrogen is replaced by halogens in fatty acids the 

 strength of the acids is increased and greater stability of the 

 esters of such substituted acids than of the esters of unsubstituted 

 acetic acid toward the hydrolytic action of water in the presence 

 of a strong catalyzing acid, may be expected. It was shown in 

 a previous paper* from this laboratory that the methyl, ethyl, 

 propyl and isobutyl esters of chlor and brom substituted acetic 

 acids have smaller velocities of hydrolysis in the presence of 

 hydrochloric and hydrobromic acids than the corresponding 

 esters of unsubstituted acetic acid. These results are in accord 

 with the theory that a substance most readily undergoes hydrol- 

 ysis if it is formed by the combination of a weak acid and a 

 weak base.f 



In view of the results obtained from the esters of halogen 

 substituted acetic acids it seemed desirable to make a further 

 study of the rates of hydrolysis of esters of substituted acids. 

 Cyanacetic acid being more strongly dissociated than the mono- 

 halogen substituted acetic acids, it is to be expected that ethyl 

 cyanacetate would be even more stable than the ethyl esters of 

 these acids. However the great difference in the rates of 

 hydrolysis of ethyl cyanacetate and ethyl chloracetate under the 

 same conditions of temperature and concentration of ester and 

 catalyzing acid, recorded in Table I, can scarcely be explained 

 on this theory alone. The dissociation constants of acetic 

 acid, chloracetic acid and cyanacetic acid are in the ratio 

 1 : 86 : 205, and the velocity constants of the ethyl esters of 

 these acids taken in the same order have a mean ratio, calcu- 

 lated from Table I, of 6'5 : 4*2 : 1. The rate of hydrolysis of 

 ethyl cyanacetate is lower than would be expected from a com- 

 parison of the dissociation constants of the acids and the rates 

 of hydrolysis of ethyl acetate and ethyl chloracetate. 



Preparation of Esters. — The ethyl cyanacetate used in the 

 hydrolysis experiments recorded in this paper was prepared 

 from recrystallized monochloracetic acid by the method of 

 Phelps and Tillotson4 Five hundred cubic centimeters of 

 the crude ester were fractioned under diminished pressure and 

 200 cmS of the pure ester boiling at 95-J C. at a pressure of 12 mm 

 were obtained. The ethyl monochloracetate was prepared by 

 boiling for six hours with a reflux condenser a mixture of 100 



* Thi8 Journal, xxx, 72. f Nernst, Theoretical Chemistry, p. 521. 



J Ibid., xxvi, 267. 



