Efficient Methanolytic Cleavage of Phosphate, Phosphonate, and Phosphonothioate Esters Promoted by Solid Supported Lanthanide Ions

Abstract

The methanolyses of three neutral organophosphorus esters, namely paraoxon (O,O-diethyl O-p-nitrophenyl phosphate (12), O-ethyl O-p-nitrophenyl methylphosphonate (13), O-ethyl S-3,5-dichlorophenyl methylphosphonothioate (14, a model for VX), and an anionic phosphonate ester, O-hydrogen S-3,5-dichlorophenyl methylphosphonothioate (15, a model for a toxic hydrolytic decomposition product of VX known as EA2192)), promoted by solid supported lanthanide ion catalysts (La3+, Sm3+, Eu3+, Yb3+) were investigated at 25 °C under sspH controlled conditions in methanol. The supports were derived from commercially available chlorobenzylated silica and chloromethylated polystyrene functionalized with two chelating ligands, iminodiacetic acid (IDA) and ethylenediamine-N,N′-diacetic acid (EDDA), followed by exposure to Ln3+ ions. The catalysts showed good activity at two investigated sspH values of 8.8 and 11 (in methanol). Despite the fact that the methoxide promoted reactions for the four substrates span a range of ∼20...