Synthesis and chemistry of photosphonic derivatives

Abstract

A reliable method for the preparation of alkylphosphonyl chlorides had to be obtained to prepare precursors for the synthesis of a range of alkylphosphonates which were needed for kinetic studies. Both thionyl chloride and oxalyl chloride were studied as chlorinating agents for phosphonic esters. The use of thionyl chloride together with a catalytic amount of DMF were shown to be of general application in the efficient preparation of phosphonic mono-ester chlorides. A wide range of esters of the formula R2NCH2CH2OPO(R')R", R, R' = CH3, CH2CH3 and R" = OCH3 , OCH2CH3, OCH(CH3) 2 and Cl were synthesized. These compounds were used as substrates to study the kinetics of their unimolecular decomposition. From the relative kinetic data we were able to show that two mechanisms of decomposition were followed depending I on the nature of the leaving group present in the substrate molecule