Efficient Semihydrogenation of the C-C Triple Bond Using Palladium on Pumice as Catalyst

An efficient semihydrogenation of C-C triple bonds was achieved using palladium on pumice as the catalyst with a metal loading of 3% wt. The results obtained showed better selectivity when compared with Pd/C and better activity when computed with Lindlar's catalyst. Hydrogenation of sterically hindo'ed alkynes is slow on Pd/pumice. The selectivity with respect to alkenes is probably due to the presence of sodium ions in the pumice structure that increases the electron density on the supported metal.