DERIVATIVES OF ALCOHOLS AND ACIDS 59 



The general reaction of esterification or ethereal salt forma- 

 tion is one of the best examples we have of reversible reactions. 

 By modifying conditions many esterification reactions can be 

 made to go in the reverse way. 



On the other hand an ester when boiled with water will take 

 up water and be resolved into its constituent acid and alcohol. 

 This reaction, like that of esterification, does not proceed to 

 completion because as soon as some free acid and alcohol are 

 formed they begin to react in the reverse way and re-form the 

 ester. If, however, some alkali is present to react with the free 

 acid as fast as it is formed, then the decomposition of the ester 

 goes on to completion. 



Thus, in esterification, a water absorbing substance must be 

 present and in the decomposition of esters alkali must be pres- 

 ent. The reaction in both cases is, however, due to water, 

 i.e. loss of water in esterification and addition of water in the 

 decomposition of the ester. 



-H2O 

 CH3-COO-(H+HO)-C2H5+(H2S04) -> CH3-COO-C2H5 



Esterification 

 + H2O 



CH3 - COO - C2H5 + (KOH) -> CHa - COOH + HO - C2H5 



Hydrolysis 



Hydrolysis. — The second reaction, the decomposition of the 

 ester, because it involves the addition of water, is termed 

 hydrolysis. Hydrolysis and esterification are, therefore, re- 

 spective names for the two forms of this reversible reaction. 

 We have used as our illustration one of the simple esters, viz. 

 ethyl acetate. All esters, however, are subject to these same 

 generalizations. 



The esters of glycerol and the fatty acids, i.e. the fats and 

 oils, undergo the reaction of hydrolysis when boiled with water 

 containing an alkali. When the hydrolysis occurs, the alcohol 

 (glycerol) and the acid (butyric, palmitic, stearic, etc.) are 

 re-formed. The glycerol remains free, but the acid reacts 



