Synthesis of aniline

In gas phase reactions the size of catalyst libraries can be over couple of thousands. For instance, in the synthesis of aniline by direct amination of benzene around 25000 samples were screened in about a year [15], however, the optimization method used was not discussed. In contrast, in liquid phase reactions taking place at elevated pressure and temperature, due to technical difficulties the rational approach does not allow testing libraries containing more than 200 250 catalysts. Consequently, the informatic platform and the strategy used to design catalyst libraries for high-pressure liquid phase reactions should have very unique optimization tools. 

Trifluoroacetamide may be successfully employed as a nucleophile in the synthesis of aniline complexes. The formation of aniline derivatives 14g can be realized by adding the in situ generated trifluoroacetamide anion CF3CONH to the o-chlorotoluenetricarbonyl-chromium complex 14a followed by KOH treatment (Scheme 21) [31]. 

The synthesis of aniline derivatives can also be realized by direct addition of the NH2 unit, if the arene ring is made more electrophilic through activation by a trifluoromethyl group. For example, in the case of p-trifluoromethykhlorobenzenetricarbonylchromium complex 47, the aniline derivative 48 can be obtained in 32 % yield using NaNH2/NH3 in HMPT (Scheme 22) [11]. 

Tsukinoki, T. Hirohisa, Tsuzuki. Organic Reaction in Water. Part 5. Novel Synthesis of Anilines by Zinc Metal-Mediated Chemoselective Reduction of Nitroarenes, Green Chem. 2001, 3, 37-38. 

A certain amount of phenol, as well as the cresols, is obtained from coal tar (Sec. 12.4). Most of it (probably over 90%) is synthesized. One of the synthetic processes used is the fusion of sodium benzenesulfonate with alkali (Sec. 30.12) another is the Dow process, in which chlorobenzene is allowed to react with aqueous sodium hydroxide at a temperature of about 360°. Like the synthesis of aniline from chlorobenzene (Sec. 22.7), this second reaction involves nucleophilic substitution under conditions that are not generally employed in the laboratory (Sec. 25.4). 

Among many other experiments that Hofmann undertook with aniline was treatment of the indigo-derived base with chlorine. He identified the products. They were used to demonstrate that the two main rival theories of chemical combination were entirely compatible. These were the electrochemical theory of attraction of Jons Jacob Berzelius and the substitution theory of Jean Baptiste Andr6 Dumas. This work was published in 1845 when Hofmann was at Bonn4. Hofmann then moved on to synthesis of aniline in... 

About the same time, Zinin, N. (1812-1880) was able, in 1842, to carry out an original synthesis of aniline, that he named benzidam, and of some other aromatic amines by reduction reaction of nitrobenzenes. As for a reducing agent, Zinin utilized a solution of ammonium sulfide to generate molecular hydrogen14,15. 

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