Facile high yielding synthesis of symmetric esters of methylenebisphosphonic acid

The 1H-tetrazole catalyzed coupling of methylenebis(phosphonic dichloride), CH2(POCl2)(2), with primary alkyl, cyclic secondary alkyl, aromatic, and s ilicon- and fluorine-containing alcohols selectively affords symmetric P,P' -dialkyl partial esters as wen as homoleptic and mixed tetraesters. Two par tial ester intermediates, methylenebis(2-ethylhexyl phosphonic chloride) an d 2-ethylhexyl methylenebisphosphonic trichloride, were observed by H-1- an d P-31 NMR spectroscopy in the esterification of CH2(POCl2)(2) with 2-ethyl -1-hexanol. (C) 2001 Elsevier Science Ltd. All rights reserved.