98 Biological Chemistry. 



Ethyl acetate, like most other esters of organic acids, 

 is a liquid with pleasant fruity odour and boiling point 

 77. It is only slightly soluble in water, but miscible 

 with organic solvents, such as alcohol, ether, etc. It is 

 like other esters, readily hydrolyzed on boiling with solu- 

 tions of alkalis and acids, yielding a mixture of the 

 alcohol and acid (or a salt of the same) from which it has 

 been prepared 



CH 3 -CO OC 2 H 5 + NaOH = C 2 H 5 OH + CH^CO-ONa 



This process of hydrolysis is known as " saponification," 

 as the sodium salts of the higher fatty acids produced in 

 the process yield soaps (see below). 



In addition to the esters of the alcohols containing only 

 one hydroxyl group, esters can also be obtained from the 

 polyhydroxy alcohols as, for example, glycol and glycerol. 

 In these substances, one or more hydroxyl groups can 

 enter into reaction, in the case of the organic acids, with 

 one or two carboxyl groups. Thus, from glycol two 

 esters can be obtained by reaction with an acid of the 

 formula R COOH, namely 



R-COOH 2 C R.CO-OCH 2 



R-CO-0-H 2 C and HOCH 2 



Glycerol, which contains three hydroxyl groups, can yield 

 esters of the general formula 



CH 2 0-OCR' 



CHOOCR" 



CH 2 -OOCR'" 



and it can also yield esters in which only one or two of 

 the hydroxyl groups have undergone condensation with 

 a carboxylic acid. The esters in which all the hydroxyl 

 groups have undergone condensation, which are repre- 



