Abstract: The present invention relates to a process for the preparation of alkylphosphonous acid esters which comprises a) reacting elemental yellow phosphorus with alkylating agents in the presence of a base to give a mixture which comprises, as principal constituents, the (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. The invention likewise relates to the use of the alkylphosphonous acid esters prepared by this process as precursors for further syntheses, inter alia for the preparation of crop protection agents.

Abstract: The invention relates to a process for preparing salts of dialkylphosphinic acids, which comprises a) reacting alkylphosphonous and/or hypo- phosphorous acid and/or alkali metal salts thereof with olefins in the presence of a free-radical initiator to give dialkylphosphinic acids and/or alkali metal salts thereof and b) reacting the dialkylphosphinic acids and/or alkali metal salts thereof obtained according to a) with metal compounds of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na and/or K to give the metal dialkyl20 phosphinate salts.

Abstract: The invention relates to a process for the preparation of dialkylphosphinic acids and salts thereof, which comprises a) reacting elemental yellow phosphorus with alkylating agents in the presence of a base to give a mixture which comprises, as principal constituents, the (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 the corresponding ester of the dialkylphosphinic acid from the ester of the alkylphosphonous acid by free-radical-initiated reaction with olefins, e) converting the ester of the dialkylphosphinic acid into the free acid or into the dialkylphosphinic acid salts of metals from groups IA, IIA, IIIA, IVA, VA, IIB, IVB, VIIB or VIIIB of the Periodic Table or of cerium.

Abstract: The invention relates to a process for preparing salts of dialkylphosphinic acids, which comprises a) reacting alkylphosphonous and/or hypophosphorous acid and/or alkali metal salts thereof with olefins in the presence of a free-radical initiator to give dialkylphosphinic acids and/or alkali metal salts thereof and b) reacting the dialkylphosphinic acids and/or alkali metal salts thereof obtained according to a) with metal compounds of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na and/or K to give the metal dialkylphosphinate salts. The invention likewise relates to the use of the metal dialkylphosphinate salts prepared by the process according to the invention for preparing flame retardants.

Abstract: The invention relates to a process for preparing dialkylphosphinic acids and/or alkali metal salts thereof by reacting olefins with alkylphosphonous and/or hypophosphorous acid and/or alkali metal salts thereof, which comprises carrying out the reaction in the presence of a azo free-radical initiator. The invention also relates to the use of the products prepared by the abovementioned process for preparing flame retardants.

Abstract: The invention relates to a process for preparing dialkylphosphinic acids and/or alkali metal salts thereof by reacting olefins with alkylphosphonous and/or hypophosphorous acid and/or alkali metal salts thereof, which comprises carrying out the reaction in the presence of a free-radical initiator. The invention also relates to the use of the products prepared by the abovementioned process for preparing flame retardants.

Abstract: The invention relates to a process for preparing salts of dialkylphosphinic acids, which comprises a) reacting alkylphosphonous and/or hypophosphorous acid and/or alkali metal salts thereof with olefins in the presence of a free-radical initiator to give dialkylphosphinic acids and/or alkali metal salts thereof and b) reacting the dialkylphosphinic acids and/or alkali metal salts thereof obtained according to a) with metal compounds of Mg, Ca, Al, Sb, Sn, Ge, Ti, Zn, Fe, Zr, Ce, Bi, Sr, Mn, Li, Na and/or K to give the metal dialkylphosphinate salts. The invention likewise relates to the use of the metal dialkylphosphinate salts prepared by the process according to the invention for preparing flame retardants.