Patent ID: 7348396

Claim:
A process for preparing a polymeric phosphinic acids or its salt of the formula (I) where X is hydrogen or, 1/m of a metal of valency m, or is a protonated nitrogen base, R 1 and R 2 are identical or different and are hydrogen, a carboxy group, a carboxylic acid derivative, an unsubstituted or substituted alkyl group having from 1 to 10 carbon atoms, phenyl, benzyl, or alkyl-substituted aromatic systems, R 3 and R 4 may be identical or different and are an unsubstituted or substituted alkyl group having from 2 to 20 carbon atoms, or are OX, with the above meaning for X, and ū is the average number of monomer units comprising the steps of reacting hypophosphorous acid and/or its alkali metal salts with alkynes (acetylenes), of the formula (II) R 1 —C≡C—R 2 (II) where R 1 and R 2 are identical or different and are hydrogen, a carboxy group, a carboxylic acid derivative, an unsubstituted or substituted alkyl group having from 1 to 10 carbon atoms, phenyl, benzyl, or alkyl-substituted aromatic systems, and oxidizing the resultant phosphonous acid end groups to give phosphonic acid end groups.