ASYMMETRIC HYDROGENATION OF 1,1,1-TRIFLUOROACETONE

The invention relates to the preparation of enantiomerically pure (S)-1,1,1-trifluoro-2-propanol by asymmetric hydrogenation of 1,1,1-trifluoroacetone which process comprises hydrogenating 1,1,1-trifluoroacetone in the presence of a ruthenium phosphine complex catalyst represented by formula Ru(E)(E')(L)(A) wherein E, E' are both chloro or E is hydrogen and E' is BH4; L is a chiral diphosphine ligand; and A is an optionally chiral diamine wherein hydrogenation occurs in the presence of a weak base, with or without an additive, when E and E' are both chloro or b) in the absence of a base and an additive when E and E' are hydrogen and BH4.