Studies on the Silk-Rhodium Catalyst

Abstract 1) The most active catalyst was obtained when 400 mg. of silk-fibroin was boiled with 30 ml. of 0.5% aqueous solution of rhodium chloride for ca. 30 min., and the resulting chelate was then reduced. 2) The activity of this catalyst was not influenced significantly by the conditions for its preparation and was maintained or even increased greatly on storage for a long period. Benzyl mercaptan, ferric and cupric ions poisoned the catalyst, but the inhibition by the metal ions could be restored by ethylene-diaminetetraacetic acid. 3) This catalyst was extremely active for the hydrogenation of the types C=C double bonds C=CHCH2OH and C=HCOOH but inactive for carbonyl groups. For the hydrogenation of other types of C=C double bonds and of nitro groups, the catalyst seems to be less active.