136 CHEMICAL PROPERTIES AND COMPOSITION 



It is quite different for saponification by acids. The 

 nature of the alcohol has then a very subordinate influence 1 ; 

 for the acetic esters with normal hydrochloric acid at 40 

 the following numbers were observed : 



Methyl- Ethyl- Propyl- Isobutyl- Isoamyl acetate 



0-0126 0-0131 0-0129 0*0129 0-0124 



Phenyl acetate Triacetin 



0-0076 0-006 



On the other hand, the acid has a far-reaching influence, as 

 appears on comparing the velocities for the following ethyl 

 esters : 



Ethyl-formate Acetate Chloracetate Dichlor acetate 



0-253 O.OI3I 0-0076 0-0122 



Trichloracetate Propionate Butyrate Isobutyrate 



0-2 0-014 O'Oo8 0-0078 



Valerate Benzoate 



0-00276 0-00007 



This effect of the acid is far less marked when the 

 saponification is produced by a base ; the following 

 numbers are from Reicher for the velocities with soda 

 at 14-4 : 



Ethyl acetate Ethyl propionate Ethyl butyrate Ethyl isobutyrate 

 3-2 2-82 1-7 1-73 



Ethyl isoralerate Ethyl benzoate 



0-61 0-83 



differences which may very well depend on the different 

 rates of diffusion of the esters. 



All these data lead to the conclusion that on saponification 

 by alkali the ester molecule, 



ZOA 

 is attacked between the alcohol radicle and the oxygen. 



1 Loewenherz, Zeitschr. f. Phys. Chun. 15. 395 ; de Hemptinne, 1. c. 13. 

 516. In harmony with this it appears that the effect of temperature on 

 saponification of acetic esters by hydrochloric acid is the same, but not 

 on that of the esters of different acids. Price, Kongl. Svenska Akad. 1899, 

 930. 



