Dehydrogenation – Homogeneous

Abstract

Homogeneous catalysts for the dehydrogenation of organic substrates, particularly alkanes and other hydrocarbons, are reviewed. The dehydrogenation of hydrocarbons results in the addition of an unsaturated site to an organic substrate; it is therefore, in principle, a reaction with almost unlimited potential value in the areas of commodity‐ and fine‐chemical synthesis. Most of this potential has not yet been realized; with respect to the use of heterogeneous catalysts the major obstacles involve the difficulty in achieving regio‐ and chemoselectivity. Homogeneous dehydrogenation catalysts offer the promise of much greater selectivity, but thus far have not afforded economically viable yields and turnover numbers. Thus, at present, homogeneous hydrocarbon dehydrogenation is an active area of research rather than an important industrial process. Several platinum‐group transition metal complexes have shown particular promise for alkane dehydrogenation; these are discussed in detail. Selectivity and high yields are both more readily achieved in the case of dehydrogenation of HCCH units that are adjacent to functional groups; several catalysts for such reactions are examined.