A rapid synthesis of diisopropyl 4-(chloromethylbenzyl) and 4-(bromomethylbenzyl) phosphonates

摘要

Our interest in the synthesis of 4-(chloromethylbenzyl) and 4-(bromomethylbenzyl) phosphonic acids esters 2 stems from their possible use for the preparation of mixed metal-phosphonate materials~1 which generally possess a layered structure.~2 The use of these esters in the synthesis of such materials could offer hybrid organic-inorganic materials possessing a halomethyl group in the interlayer space as found in Merrifield redins.~3 Such materials should have beeter thermal stability and larger porosity than the classical Merrifield resin. The diethyl ester of 4-(chloromethylbenzyl) hosphonic acid had been obtained by Bigge et al.~4 in poor yield (20-25) by the Michaelis reaction of sodium diethyl phosphite with alpha,alpha'-dichloro-p-xylene. The dimethyl ester of 4-(bromomethylbenzyl) phosphonic acid was prepared by Baczco et al.~5 from p-methylbenzyl bromide as the substrate via an Arbuzov reaction, followed by radical bromination; although the overall yield is good (52), the presence of polybromination side-products makes purification of the product difficult.