Patent ID: 7572931

Claim:
A process for the production of dialkyldithiophosphinic acid comprising sulfurizing a purified dialkylphosphinic acid whereby said purified dialkylphosphinic acid is formed by: a) reacting a hypophosphorous acid or salt with a stoichiometric excess of an alpha olefin in the presence of a free radical initiator to form a reaction product comprising monoalkylphosphinic acid and dialkylphosphinic acid; b) adding sufficient aqueous base to the reaction product to i) form the salts of the phosphinic acids, and ii) establish an aqueous phase and an organic phase, wherein a monoalkylphosphinic acid solubilizes into an aqueous phase; c) separating the organic phase from the aqueous phase; d) acidifying the organic phase; e) removing the olefin from the organic phase; and f) isolating the purified dialkylphosphinic acid product.