HYDROGENATION CATALYST MADE FROM CHLOROPLATINIC ACID AND TRIETHYLSILANE

An active hydrogenation catalyst is readily made as a suspension by warming chloroplatinic acid with triethylsilane in 95% ethanol. The activity, which is associated with the suspended solid particles, is retained on prolonged storage. The catalyst is more active than Adams catalyst for (a) hydrogenation of simple olefins such as oct-1 -ene and cyclohexene, (b) hydrogenation of alkynes, (c) hydrogenation of N=N and C=N double bonds in azobenzene and benzylidineazine, respectively, (d) reduction of aromatic nitro-compounds to amines, and (e) hydrogenolysis of allyl bromide and chloride. It is less active than Adams catalyst in hydrogenolysis of fluoro- and chloro-benzene, and in hydrogenation of benzene, but is a little better than that catalyst in hydrogenation of dimethylaniline. It is better than the (unsupported) catalyst produced by interaction of chloroplatinic acid and sodium borohydride except in hydrogenolysis of fluoro- and chloro-benzene. The activity of the catalyst from the borohydride in hydrogenation of oct-1-ene has been found to depend on the concentration of hydrochloric acid, being greatest in the presence of a very small amount of acid. Catalysts made by reduction of platinum oxide with triethylsilane or of potassium chloroplatinite with ethanol are better than Adams catalyst in some reactions.