Silicon-phosphorus analogies. nucleophilic catalysis in the alcoholysis of chlorophosphorus derivatives

The mechanism of the alcoholysis of chlorophosphonates and chlorophosphates in the presence of nucleophilic catalysts like hexamethylphosphotriamide, pyridine and N-methylimidazole is discussed on the basis of kinetic and stereochemical results. We have proposed a mechanism for the reaction, which is governed by entropy, involving reaction of the alcohol with a pentacoordinated intermediate. This accounts for the differences in the stereochemical outcome and the rate equation which can be derived for the reaction with a variety of substrates in addition to the absence of common ion + solvent effects observed.