有机磷化合物的研究 ⅩⅩⅩⅨ.溶剂性质对烷基膦酸-O,O-1,3-丙二酯及-O,O-1,4-丁二酯的碱性水解动力学的影响

Studies on Organophosphorus Compounds ⅩⅩⅩⅨ. Solvent Effect on the Alkaline Hydrolysis of 2-Alkyl-2-oxo-1, 3-dioxaphosphorinane and-phosphepane

本文报道烷基膦酸-O,O-1,3-丙二酯及O,O-1,4-丁二酯于50％二甲亚砜水溶液中的水解动力学,考察了取代基结构对膦酸酯水解速率常数的影响.通过它们在50％的二甲亚砜水溶液和50％的二氧六环水溶液中碱性水解速率常数的比较,说明在这些混合溶剂中,烷基的空间结构对水解速率常数的影响是近似平行的.同时,正丙基膦酸-O,O-1,3-丙二酯于不同混合溶剂中碱性水解时,溶剂分子的给质子和接受质子的能力对水解反应过程有重要影响.

The kinetic behaviour of alkaline hydrolysis of 2-alkyl-2-oxo-1, 3-dioxaphosphorinane and-phosphepane (simplified as O, O-trimethylene and O, O-tetramethylene alkylphoaphonates respeotively for convenience) in various solvents was investigated. In 50% aqueous dimethylsulfoxide, alkaline hydrolysis of these two cyclic esters of alkylphosphonates behaves as second order reaction. Multiple regression analyses involving logk with σ and △△E gave very good results. It showed that the alkyl snbstituent effect on the rate of hydrolysis of these alkylphosphonates bearing six or seven membered ester ring in alkaline medium is very similar. For the evaluation of solvent effect, the rate constants of basic hydrolysis of O, O-trimethylene alkylphosphonates in various aqeotis solvent including acetone, ethanol, t-butanol, dimethyl glycol, dioxane and DMSO were examined. It was found that logk do not relate either with dielectric constant or with solvent parameter E_T. However, the strength of proton-donor and acceptor solvents showed significant influence on the alkaline hydrolysis of the titled compounds.