Selective catalytic hydrogenation of acetylenes

Abstract

The products of the stepwise catalytic hydrogenation of undeca-1,7-diyne (I) have been examined and the sequence of the reduction established. The ethynyl group may be protected during catalytic hydrogenation by conversion into the corresponding 1-bromoacetylene. Certain palladium catalysts have been shown to produce substantial amounts of trans-ethylene in the catalytic partial reduction of several acetylenic hydrocarbons. Catalytic stereomutation of cis- to trans-ethylene has been observed, the extent of which depends on the relative proportions of catalyst and unsaturated hydrocarbon.