Production of 1-hydroxyalkylidene-1, 1-diphosphonic acid esters

摘要

Acylated 1-hydroxyalkylidene-1, 1-diphosphonic acid (HADPA) can be produced almost instantaneously with less than 5% (by weight) phosphorus acid byproduct by introducing PX3 (where X is a halide) into a reactor containing R-COOH at or above a specified temperature. The acylated HADPA can then be hydrolyzed and substantially pure HADPA obtained by vacuum distillation. Of particular importance is the addition of PCl3 to acetic acid at a temperature of between 105 DEG C. and 120 DEG C. to produce acetylated 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDPA).