INVESTIGATION OF MECHANISM OF CATALYTIC REDUCTION OF NITROBENZENE AND CERTAIN OF ITS DERIVATIVES,

摘要

Investigated were the kinetics of reduction of nitrobenzene,nitrobenzene-aniline intermediate products,their binary mixtures and a number of substituted nitrobenzenes on Raney nickel,platinum and palladium at atmospheric pressure of hydrogen and low temperatures. Data of catalytic reduction of mixtures of nitrobenzene-aniline products and analysis of reaction mixture in the course of reduction of nitrobenzene indicate that along with hydrogenation, i.e.,successive interaction of nitro group with three molecules of hydrogen,there is possible non-catalytic bonding of intermediate products of nitrosobenzene and phenol hydroxylamine,leading to the formation of azoxybenzene,which further is transformed into aniline through azo-and hydrazobenzene. The path along which the process chiefly goes depends on the numerical ratio of reacting components on the surface of catalyst,which in turn,is determined by the nature of catalyst,temperature,composition of solvent,concentration of reducible substance,presence of different additions in the reaction mixture etc. Nature of the substituent does not always predetermine the effect which it will have on the speed of heterogeneous-catalytic reaction. (Author)