The Hydroxide-Blacks of Ruthenium and Rhodium as Catalysts for the Hydrogenation of Organic Compounds. II. The Effects of Solvents and Added Alkalis in the Hydrogenation of Aniline

The hydrogenation of aniline with the hydroxide-black catalysts of ruthenium and rhodium was investigated, using various alcohols as solvents. The formation of dicyclohexylamine increased in the following order with respect to the solvents: t-butyl alcohol≅isopropyl alcohol << ethyl alcohol < methyl alcohol. It was shown that the addition of a small amount of alkali greatly hinders the formation of dicyclohexylamine. The effects of added ammonia and dicyclohexylamine were also investigated. The addition of ammonia retarded the rhodium-catalyzed hydrogenation much more seriously than the hydrogenation with ruthenium, but it was found that in the presence of alkali the hydrogenation with rhodium was not inhibited by the addition of ammonia.