Selective Semihydrogenation of Alkynes with N-Graphitic-Modified Cobalt Nanoparticles Supported on Silica

For the first time N-graphitic-modified cobalt nanoparticles (Co/phen@SiO 2 -800) are shown to be active in the semihydrogenation of alkynes to alkenes. Key to success for efficient catalysis is both the modification of the metal nanoparticles by nitrogen-doped graphitic layers and the use of silica as support. Several internal alkynes are converted to the Z isomer in high yields with up to 93% selectivity. In addition, a variety of terminal alkynes, including sensitive functionalized compounds, are readily converted into terminal alkenes. Notably, this non-noble-metal catalyst allows for the purification of alkenes by selective hydrogenation of the corresponding alkyne in the presence of an excess of olefin.