Nitroso amines methyl aniline

Nitrosamine and para Nitroso Methyl Aniline.—The reaction with nitrous acid is characteristic of secondary amines and yields phenyl methyl nitrosamine, the nitroso group entering the amino radical. This, however, undergoes rearrangement with the transference of the nitroso group to the ring yielding a nitroso benzene compound. 

Nitrous acid derivatives in which the nitroso group enters the ring are formed by the direct action of nitrous acid only in the case of the tertiary amines, e.g., di-methyl aniline as already described (p. 552). 

The rearrangement occurs also when nitro benzene is electrolytically reduced by immersing the cathode in nitro benzene and sulphuric acid and the anode in sulphuric acid. Phenyl hydroxyl amine is first produced and by the above rearrangement is converted into para amino phenol. This rearrangement is analogous to the one occurring when phenyl methyl nitrosamine goes over to para-nitroso methyl aniline (P- S59)-... 

Rearrangement.—Like nitroso methyl aniline and phenyl hydroxyl amine it undergoes molecular rearrangement as above. 

Secondary and tertiary amines are not generally prepared in the laboratory. On the technical scale methylaniline is prepared by heating a mixture of aniline hydrochloride (55 parts) and methyl alcohol (16 parts) at 120° in an autoclave. For dimethylaniline, aniline and methyl alcohol are mixed in the proportion of 80 78, 8 parts of concentrated sulphuric acid are added and the mixture heated in an autoclave at 230-235° and a pressure of 25-30 atmospheres. Ethyl- and diethyl-anihne are prepared similarly. One method of isolating pure methyl- or ethyl-aniline from the commercial product consists in converting it into the Y-nitroso derivative with nitrous acid, followed by reduction of the nitroso compound with tin and hydrochloric acid ... 

Condensation of aromatic nitroso compounds with primary amines is a satisfactory procedure for obtaining azo compounds. An example is the combination of nitrosobenzene and aniline in acetic acid, which results in a quantitative yield of azobenzene. Similarly, a series of methyl-substituted azobenzenes have been prepared, although the yields are poor in the case of the oriAo-substituted compounds. As an illustration of the versatility of the reaction, nitrosobenzene can be condensed with o-methoxyaniline (o-anisidine)," p-aminobenzoic acid, o-phenylene-diamine monobenzoate, and m-nitroaniline to form the corresponding substituted azobenzenes. 

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