Platinum-Catalyzed Racemization of 1,1'-Binaphthyl

Article abstract of DOI:10.1021/jo00343a002

The racemization of 1,1'-binaphthyl in ethanol is subject to heterogeneous catalysis by platinum (prepared by reduction of platinum oxide with hydrogen).The rate of catalyzed reaction is first order in binaphthyl but independent of platinum concentration over a limited range.First-order rate constants at 25 deg C decrease with increased binaphthyl concentration and are up to 12-fold that for the uncatalyzed racemization.Catalysis by platinum is stopped momentarily by the injection of air and is diminished by injection of cyclohexene or cyclohexane into the solution.Racemization therefore occurs on active sites which are also capable of reducing oxygen or cyclohexene.It is suggested that, for racemization of binaphthyl, these sites are acting as electron donors rather than hydrogen atom donors.