Patent ID: 6359171
Filing Date: 2002-03-19
Classification: C07F

Abstract:
A process for the preparation of dialkylphosphinic acids and salts thereof, which comprisesa) reacting elemental yellow phosphorus with alkylating agents in the presence of a base to give a mixture which comprises, as principal constituents, metal salts of alkylphosphonous, phosphorous and hypophosphorous acids, b) esterifying the principal constituents of the mixture from a) to give an ester mixture, c) isolating the ester of the alkylphosphonous acid from the ester mixture, d) preparing a corresponding ester of the dialkylphosphinic acid from the ester of the alkylphosphonous acid by free-radical-initiated reaction with olefins, and e) converting the ester of the dialkylphosphinic acid into a free acid or into dialkylphosphinic acid salts of cerium or metals from groups IA, IIA, IIIA, IVA, VA, IIB, VIIB or VIIIB of the Periodic Table.