Phosphorus-31 nuclear magnetic resonance study of the mechanism and kinetics of the hydrolysis of zinc(II)O,O-diethyl dithiophosphate and some related compounds
Abstract
31 P NMR spectroscopy has been used to investigate the mechanism and kinetics of hydrolysis of Zinc(II)O,O-diethyl dithiophosphate (1)(ZDTP) in 1,2-dimethoxyethane solution at 85 °C with ten equivalents of water. All major intermediates and products have been identified and the individual reaction rates determined. ZDTP was found to be hydrolysed (k= 2.35 × 10–4 s–1) to phosphoric acid (7)via O,O-diethyl S-hydrogen dithiophosphate (3)(Khyd= 1.35 × 10–2 s–1) and thiophosphoric acid (6)(Khyd= 0.78 × 10–5 s–1). O-Ethyl O,O-dihydrogen and O,O-diethyl O-hydrogen phosphorothioates (8), (9), and ethyl dihydrogen phosphate (10) were produced as by-products of the reaction. From a study of the order of appearance of the intermediates and products, a detailed mechanism for the hydrolysis of ZDTP has been proposed. O-Ethyl O,S-dihydrogen phosphorodithioate (4) and dithiophosphoric acid (5) are found to be intermediates.