Application of 3H n.m.r. Spectroscopy to metal catalysis. Orientation of incorporated isotope in halogenated benzenes and alkylbenzenes tritiated by heterogeneous platinum exchange

Abstract

³ H N.m.r. spectroscopy is shown to be a powerful tool for the mechanistic study of metal catalysed reactions; using the technique, data obtained from a re-investigation of platinum catalysed isotopic hydrogen exchange correct previously reported anomalous ortho effects in the halogenated benzenes and also, with the alkylbenzenes, provide additional orientation information which supports the predominant participation of a π-dissociative process for the heterogeneous system; steric and not electronic effects appear to determine the pattern for degree of exchange.