Optical rotation and absolute configuration of chlorofluoroacetic acid
Abstract
Chlorofluoroacetic acid, [α]D25– 55·8°(benzene), was shown to be of at least 98% optical purity by n.m.r. analysis of its adduct with (–)-1,2-epoxy-1-phenylcyclohexane. An X-ray diffraction study on the adduct of the (+)-acid with the (–)-epoxide has established that (+)-chlorofluoroacetic acid has the S-configuration, in contrast with expectation on the basis of the Brewster polarizability rule.