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Mechanistic aspects of alkenes hydrogenation and deuteration catalyzed by dispersion of hydroxyhydridorhodium colloids in aqueous medium

1990; Science Press; Volume: 61; Issue: 1 Linguagem: Inglês

10.1016/0304-5102(90)85195-n

1873-3131

Chantal Larpent, Henri Patin,

Asymmetric Hydrogenation and Catalysis

Deuterium in D2O or H2O and alternatively hydrogen in D2O are used for the preparation of a catalytic system based on RhCl2·3H2O and P(m-C6H4SO3Na)3 as starting materials. The aqueous dispersion of rhodium colloidal species is used for the hydrogenation of alkenes in biphasic systems. High levels of isotope incorporations are always observed and deuterium scrambling occurs when β-abstraction is possible. The results are interpreted by assuming that the colloidal rhodium catalyst contains hydridohydroxy species on which cis -hydrogenation (deuteration) of alkenes is performed. The catalytically active species are most probably regenerated by competitive oxidative additions of either D2O (H2O) or H2 (D2); moreover, H/D exchange in the coordination sphere may also contribute to isotope incorporation.