Abstract: The present invention concerns a catalytic composition comprising a catalyst effective for catalysing asymmetric hydrogenation reactions, which catalyst requires acid activation, an acidic material effective for activating the catalyst, and a buffering compound or composition capable of forming, in the presence of the acidic material, an acetal, a ketal, a hemiacetal, and/or a hemiketal. The invention also relates to an asymmetric hydrogenation process utilising such a catalytic composition, and to the use of such a catalytic composition for improving the enantiomeric excess of a desired asymmetrically hydrogenated product.

Abstract: The present invention relates to a reactor comprising a plurality of reaction zones, a first reaction zone being configured to provide a first residence time for a reaction mixture passing therethrough at a particular flow rate, and a second reaction zone connected in series with the first reaction zone and configured to provide a second residence time for the reaction mixture passing therethrough at the particular flow rate, wherein the second residence time is at least about 1.5 times greater than the first residence time, the reactor further comprising means for bypassing at least one of the first and second reaction zones to reduce the effective residence time of the reaction mixture passing through the reactor.