ALKYL AND ARYL ANILINES

As aniline, toluidine, xylidine, etc., are primary amines if we substitute alkyl or aryl radicals for one or both of the remaining amino hydrogen atoms we shall obtain secondary and tertiary amines. Such products may be typified by the following in which the methyl and phenyl radicals are substituted for the amino hydrogen in aniline. 

These compounds are exactly analogous to mono-methyl amine, primary di-methyl amine, secondary, and tri-methyl amine, tertiary and the reactions distinguishing the three groups of aromatic compounds are analogous to those given for the aliphatic amines (p. 59). The resulting products, however, are in some cases distinctly different, showing a difference between the paraffin and benzene compounds. 

Reactions with Nitrous Acid.—With nitrous acid (HO—NO) primary amines, due to the presence of two remaining ammonia hydrogen atoms, react with the oxygen of nitrous acid which is linked directly to the nitrogen alone. In the case of the alkyl amines the reaction does not stop here, but the hydroxyl group of the nitrous acid unites with the alkyl radical forming an alcohol and the nitrogen is set free. 

Primary Amines.—With aromatic amines the reaction may be stopped at the end of the first step and, as recently explained (p. 542), a new type of compound known as a diazo compound is obtained. This may be decomposed on raising the temperature and the rest of the reaction effected. This may be illustrated as follows  

Secondary Amines.—With secondary amines, due to the presence of only one remaining ammonia hydrogen atom, the reaction involves only the hydroxyl group of the nitrous acid and the nitroso group, (—NO), enters the amine in place of the remaining ammonia hydrogen. In this case the alkyl amines and the aromatic amines react alike as follows  

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