Drushel and Dean — Hydrolysis of Esters. 293 



Art. XXIX. — On the Hydrolysis of Esters of Substituted 

 Aliphatic Acids ; by W. A. Drushel and E. W. Dean. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — ccxxxv.] 



4. Ethyl Esters of Glycollic Acid and of Methyloxy, Ethyloxy 

 and Eropyloxy Acetic Acids. 



Previous work on the hydrolysis of the esters of aliphatic 

 acids has been reviewed in the first paper* of this series. The 

 substances which had been previously studied were the methyl, 

 ethyl and propyl acetates, the methyl and ethyl esters of chlor- 

 acetic acid, and the ethyl esters of di- and trichloracetic acids. 

 The velocity of hydrolysis of isobutyl acetate had also been 

 measured. 



It was shown in this paper that the introduction of halogen 

 into the acetyl radical lowers the rate of hydrolysis. It was 

 also shown that the esters of different alcohols and any one acid 

 differ but little in their velocities of hydrolysis in acid solution. 

 The substances studied were the methyl, ethyl, propyl and 

 isobutyl chlor- and bromacetates. In a second paperf it was 

 shown that ethyl cyanacetate hydrolyzes more slowly than the 

 chloracetate. From these results it would seem probable that 

 the rate of hydrolysis bears some relation to the strength of 

 the acids in esters and that this is in accord with the rule;}: 

 stated by Nernst for the degree of hydrolysis of salts in 

 general. Cyanacetic acid is about two and a half times as 

 strongly dissociated as chloracetic, which in turn is about 

 eighty times as strong an acid as acetic. It. was shown, how- 

 ever, that this factor does not entirely account for the differ- 

 ence in reaction velocity of the esters. 



In a third paper§ the results of work with alpha and beta 

 chlor- and brompropionic esters are published. It was found, 

 here that the ester of the beta acid hydrolyzes more slowly 

 than that of the alpha acid in the cases of both bromine and 

 chlorine substituted derivatives. This is apparently an excep- 

 tion to the theory mentioned above, as the beta acids are weaker 

 than the corresponding alpha acids. 



A study has been undertaken recently to show the effect of 

 the presence of hydroxyl and alkyloxy groups in fatty acid 

 radicals on the rate of hydrolysis. The following esters are 

 considered in this paper : ethyl glycollate, CH 2 OH.COOC 2 H 6 ; 

 ethyl methyloxy-acetate, CH 2 OCH s .COOC 2 H B ; ethyl ethyloxy- 

 acetate, CH^OC^H^COOCjHs, and ethyl propyloxy-acetate, 

 CH 2 OC 3 H,.COOC 2 H 5 . 



* This Journal, xxx, 72. f This Journal, xxxiii, 27. 



X Nernst, Theoretical Chemistry, p. 521. 

 § W. A. Drushel, this Journal, xxxiv, 69. 



Am. Jour. Sci.— Fourth Series, Vol. XXXIV, No. 201. — September, 1912. 

 20 



