Kinetics of the pinacol rearrangement of Propane-1,2-diol

Abstract

The pinacol rearrangement of propane-1,2-diol in aqueous acid gives propanal. The rate of loss of optical activity (kα) is greater than the loss of diol (kre) over the range of acid concentrations investigated. Also the ratio kα/kre decreases with the increasing acidity. A value of c. 0.5 has been obtained for the relative rates of oxygen exchange to racemization. Relative rates for the partitioning of a proposed carbocation intermediate have been calculated from these data.