128 Biological Chemistry. 



is directly united to a carbon of the alkyl group (see 

 p. 133). 



The primary amines, furthermore, decompose when 

 treated with nitrous acid with evolution of nitrogen aud 

 formation of an alcohol 



C 2 H 6 -NH a + HO NO = C 2 H 5 OH + N 2 + H.O 



(Compare the action when ammonia and nitrous acid 

 are heated together, NH 4 NO 2 = N 2 + 2H 2 0.) 



This reaction serves to distinguish primary from 

 secondary and tertiary amines. The last-named will not 

 react with nitrous acid, whereas the second-named form 

 nitroso-compounds, for example 



(C 2 H 5 ).NH + HONO = (C a H 5 )N-NO + H 2 



In this reaction no nitrogen is evolved. 



This nitrous acid reaction is an important one, not 

 only for distinguishing certain classes of amines, but also 

 as a means of synthesis of alcohols. Thus, it is possible 

 to pass from a lower to a higher alcohol by employing 

 this reaction, as is illustrated in the following formulae : 



C 2 H 6 OH > (by HBr) C 2 H 5 Br > (by KCN) C,H 5 (CN) 



> (by H 2 ) C 2 H 6 CH 2 NH 2 > (by HN0 2 ) C 2 H 5 CH 2 OH 



The following are examples of primary amines : 



Methylamine, CH 3 NH 2 boiling point, - 6 



Ethylamine, C 2 H 6 -NH 2 +19 



Propylamine, C 3 H 7 -NH 2 49 



Butylamine, C 4 H 9 -NH 2 76 



They are liquids with characteristic ammoniacal smells. 

 They are soluble in organic solvents. 



Secondary Amines. The preparation from primary 

 amines has been already described. In this process, as 

 stated, the substance is obtained mixed with tertiary and 

 quaternary ammonium compounds (and also with small 



