Deuterium Isotope Effects on the Silver

Solvent deuterium isotope effects support the view that the p-N02 and p-Me derivatives of benzaldehyde S.S-diethylacetal undergo silver ion-promoted hydrolysis in water by different mechanisms. scheme common [3] for O.O-acetals in the presence of H30 + ions, while for the latter we suggested a bimolecular A2-type mechanism with one (or more) water molecules in the slow phase of step (3). The compound with R = H may be an intermediate case [1, 2j. Solvent deuterium isotope effects are sometimes helpful in distinguishing between reaction mechanisms in solution [4], Relatively few studies, however, have examined such isotope effects in systems involving metal ion-promotion or catalysis. No general pattern of behaviour has been established in the way that it has for H30 +-catalysed processes [4], We have now studied the effect of using D,0 in place of H20 on some of the results for two of these S,S-acetals: the p-Me and p-N02 compounds.