反应详情

German Patent Specification No. 72173 discloses a method for producing an aromatic primary monoamine, such as p-nitroaniline, which comprises nitrating a benzalaniline (benzylideneaniline) which may be represented by the following formula ##STR5## wherein r represents a methyl or methoxy group and m is 0, 1 or 2, with nitric acid in sulfuric acid, and then hydrolyzing the resulting product. Example 1 of this patent document states that p-nitroaniline was obtained in a yield of 90% from benzalaniline. The German patent, however, does not at all refer to the use of an α-substituted compound of benzalaniline including the α-methylbenzalaniline represented by formula (III) given hereinabove. Furthermore, it is completely silent on the use of solvents other than sulfuric acid in the nitration reaction. The starting benzalaniline used in this patent can be obtained by condensation between benzaldehyde and aniline. Benzaldehyde, however, is not available at low cost because it is chemically unstable and its production requires a complex process and is costly. Hence, the starting benzalaniline is unsatisfactory for industrial production of p-nitroaniline at low cost.