Production of 1-hydroxyalkylidene-1, 1-diphosphonic acid esters
AssigneeAir Products and Chemicals, Inc.
InventorsWilliam E. Starner, Walter F. Yext
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Abstract
Acylated 1-hydroxyalkylidene-1, 1-diphosphonic acid (HADPA) can be produced almost instantaneously with less than 5% (by weight) phosphorus acid byproduct by introducing PX.sub.3 (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 PCl.sub.3 to acetic acid at a temperature of between 105.degree. C. and 120.degree. C. to produce acetylated 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDPA).
Claims8
In a process for producing an acylated 1-hydroxy alkylidene-1,1-diphosphonic acid (HADPA) by reacting PX.sub.3, where X is a halogen atom and RCOOH where R is an alkyl group containing from 1-18 carbon atoms to produce said acylated HAPDA, the improvement which comprises:
- introducing said PX.sub.3 to a reactor containing RCOOH;
- maintaining RCOOH during said introduction of PX.sub.3 at a temperature T such that the resulting reaction between RCOOH and PX.sub.3 results in producing a product mixture comprising acylated HAPDA and by-product phosphorous acid, said temperature being at or greater than 100.degree. C. where R is an integer from 1-4 and at or greater than 130.degree. C. where R is an integer from 5-18 carbon atoms whereby the by-product phosphorous acid detectable by iodometric titration at any time in the product mixture is less than 5% of the total weight of the acylated HADPA and phosphorous acid formed.
Dependencies are inferred from the claim text.