Extremely Active Catalysts for the Hydrogenation of Terminal Alkenes

Titanocene complexes combined with nanometer-size sodium hydride are extremely active and selective catalysts for the hydrogenation of terminal alkenes under normal pressure. The initial turnover frequencies (TOFinitial) may reach 100–300 s−1 in the hydrogenation of 1-hexene. The highest catalytic efficiency turnover (TO) reaches 1.5×105 in 2 h for the hydrogenation of styrene. These catalytic systems exhibit specific selectivity toward alkene substrates. Only terminal alkenes can be hydrogenated. No isomerization of carbon–carbon double bonds occurs during hydrogenation. A suitable substituent on the cyclopentadienyl ring of titanocene and the use of nanometric sodium hydride are key factors in the high efficiency of these catalytic systems.