94 Biological Chemistry. 



is indicated by the fact that they can be produced from the 

 primary alcohols by oxidation, the acids thus obtained 

 containing the same number of carbon atoms as the 

 alcohol, and they can be synthesized from hydrocarbons 

 through the intermediation, first, of halogen derivatives, 

 then of nitriles or cyanides, which latter substances, on 

 hydrolysis with mineral acids, yield the organic (car- 

 boxylic) acids. 



Part VII. The Esters. 



Attention has been already called to the fact (p. 67) 

 that a series of substances can be derived from inorganic 

 acids by the replacement of a hydrogen atom by an 

 alkyl radicle. The following are typical examples of 

 such derivatives : 



From HC1 C 2 H 5 C1 General formula, E-C1 



,, HI C 2 H 5 I HI 



HN0 3 C 2 H 5 N0 3 RN0 3 



HN0 2 C 2 H 5 N0 2 RN0 2 



H 2 S0 4 C 2 H 5 HS0 4 RHS0 4 



(C 2 H 5 ) 2 S0 4 B 2 .S0 4 



In the same way from organic acids of the formula 

 R CO OH a series of compounds can be derived in 

 which the (acid) hydrogen of the carboxyl group is re- 

 placed by an alkyl radicle, and which can be represented 

 by the general formula R CO OR'. Such compounds 

 may be regarded as analogous to salts of organic acids, 

 in which the hydrogen of the carboxyl group, instead of 

 being replaced by a metal, is replaced by an alkyl radicle. 

 They are, therefore, sometimes called alkyl salts of acids. 

 The substance, CH 3 CO OC 2 H 5 , if this latter method of 

 regarding these substances is adopted, may be called ethyl 

 acetate that is to say, it is a derivative of acetic acid, 

 in which the hydrogen atom is replaced by the alkyl 

 group ethyl. Substances derived from acids by the re- 



