LABELLING OF SYNTHETIC OESTROGENS OF TRANS-STILBENE AND SYMMETRICAL DIPHENYLETHANE SERIES BY CATALYTIC EXCHANGE ON HETEROGENOUS PLATINUM

Synthetic oestrogens of the trans‐stilbene and sym. diphenyl‐ethane series have been labelled by catalytic exchange with isotopic water in the presence of heterogeneous platinum. Experiment showed that platinum oxide pre‐reduced with sodium borohydride produced a more suitable catalyst for the exchange than the alternative of self‐activation. Self‐activated catalysts accentuated degradation of the substrate. The labelling method was suitable for the tritiation of all ten substances studied and also for their deuteration with the exception of 4,4′‐dimethoxy‐α‐chloro‐α‐methyl stilbene. Methoxy groups on the aromatic rings sterically hinder exchange in adjacent positions. Steric hindrance to labelling of hydrogens on the bridge carbon atoms was also noted. The results are shown to be consistent with a π‐complex adsorption mechanism. Copyright © 1969 John Wiley & Sons, Ltd.