Nitro-acetanilide benzene

Another side reaction which occurs is reduction in the reaction the —N2C1 or —N(NO)COCH3 group is replaced by hydrogen. wi-Bromo-toluene was isolated in 6% yield from the reaction between the sodium diazotate from 2-bromo-4-methylaniline and benzene, and in 10% yield in a similar reaction from 2-methyl-4-bromoaniline.4 Some nitrobenzene is obtained in the preparation of 3-nitrobiphenyl from nitroso-w-nitro-acetanilide (p. 250). The source of the hydrogen effecting the reduction has not been determined. f... 

Fig. 47. Colours of addition products of various nitro compounds with hydrocarbons and amines I - Benzene II - Xylene El - Durene IV - Naphthalene V -Acetanilide VI - Phenanthrene VII - Tribromoaniline VIE - Safrole IX - Anthracene X - Aniline XI - Diphenylamine XII - Benzidine XIII -Dimethyl-aniline (Brackman [126]).

The direct chlorination or bromination of aniline takes place more easily than that of benzene, the result being the symmetrical tri-chlor or tri-brom aniline, viz., i-amino 2-4-6-tri-chlor benzene, C6H2CI3-(NH2) and I-amino 2-4-6-tri-brom benzene, CeH2Br3(NH2). The mono-halogen anilines are prepared by reducing mono-chlor nitro benzenes, or by halogenating acetanilide and then hydrolyzing. 

Just by knowing the effects summarized in these short lists, we can now predict fairly accurately the course of hundreds of aromatic substitution reactions. We now know, for example, that bromination of nitro enzene will yield chiefly the /M-isomer and that the reaction will go more slowly than the bromination of benzene itself indeed, it will probably require severe conditions to go at ail. We now know that nitration of CeHsNHCOCH, acetanilide) will yield chiefly the o-and / -isomers and will take place more rapidly than nitration of benzene. 

These equilibria represent a more or less ideal case, since as a rule other substances are present, and also the nitro-amine which may be formed reacts farther. If sulfuric acid is present, a ternary intermediate compound would be formed. If acetanilide were used instead of aniline, the general reaction would be similar. If, however, a large excess of sulfuric acid were used in the reaction, then the aniline would be present practically entirely as aniline sulfate and there would not be the tautomeric form present. Under these circumstances, the intermediate compound would not be the same as before, and the nitration would proceed as if benzene itself were being nitrated. Mainly meta compound would be obtained under these conditions. The velocity of nitration of benzene derivatives containing different substituents was studied by H. Martinsen [Z. physik. Chem. 50, 385 (1905) 50, 605 (1907)1. He found the velocities to be dependent upon the substituents in the following way ... 

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