Studies on the metabolism of the neurotoxic tri- o-cresyl phosphate. Synthesis and identification by infrared, proton nuclear magnetic resonance and mass spectrometry of five of its metabolites

Abstract

Five metabolites of the industrial neurotoxic chemical tri- o-cresyl phosphate (TOCP) were synthesized and their structures were verified by infrared, IR; proton nuclear magnetic resonance, 1H-NMR; and mass spectrometry. The 2 acids, o-cresyl dihydrogen phosphate and di- o-cresyl hydrogen phosphate were prepared in 2 steps. Step 1, POCl 3 was reacted with o-cresol, using 1:1 and 1:2 molar ratios, in the presence of anhydrous AlCl 3 as a catalyst, to form the 2 intermediates o-cresyl phosphorodichloridate and di- o-cresyl phosphorochloridate, respectively. Step 2, the chloridate intermediates were hydrolyzed under the appropriate conditin to the corresponding acids. These acids were further derivatized to the corresponding methyl ester and the products were analyzed by the spectroscopic techniques. Saligenin cyclic- o-tolyl phosphate[2-( o-cresyl)-4 H-1:3:2-benzodioxaphosphoran-2-one] was synthesized by reacting the potassium salt of o-hydroxybenzyl alcohol with o-cresyl phosphorodichloridate. Hydroxymethyl TOCP [di- o-cresyl o-hydroxymethylphenyl phosphate] and dihydroxymethyl TOCP [ o-cresyl di- o-hydroxymethylphenyl phosphate] were synthesized by reacting di- o-cresyl phosphorochloridate with the potassium salt of o-hydroxybenzyl alcohol. The products were separated and purified by repeated preparative thin-layer chromatography (TLC) using 3 different solvent systems. The purity of the 5 metabolites, which was determined by high performance liquid chromatography (HPLC), ranged from 92% to 99%.