Kinetic Study of the Reduction of Trimethyl Phosphate, Triethyl Phosphate, and Tributyl Phosphate by Sodium in Liquid Ammonia

Article abstract of DOI:10.1021/j100311a028

The reactions of trimethyl phosphate, triethyl phosphate, and tributyl phosphate with sodium in liquid ammonia were found to be consistent with second-order kinetics, first order with respect to the ammoniated electron and first order with respect to the trialkyl phosphate.One mole of the trialkyl phosphate was found to react with two moles of sodium to yield the alkoxide and dialkyl phosphite.The second-order rate constant for trimethyl phosphate at -34 deg C was found to be (1.8+/-0.1)*10³ M^-1 s^-1.The second-order rate constants for triethyl phosphate and tributyl phosphate were determined at various temperatures.Activation energies of 5.6+/-0.2 and 7.6+/-0.2 kcal/mol were calculated for triethyl phosphate and tributyl phosphate, respectively.A mechanism in which the rate-determining step is the cleavage of an alkoxy group is suggested.