Patent ID: 7345185

Claim:
A process for preparing trivalent organophosphorus compounds which bear at least one structural unit S where A is a divalent substituted or unsubstituted alkyl or aryl radical which may form a ring system as per structural unit S, and the L radical is an organic radical bonded to the phosphorus atom via an oxygen or carbon atom, or is a halide, by condensing phosphorus compounds of the formula i PHal a R (3-a) (i) where Hal is halide selected from chlorine, bromine and iodine, and the halides may be the same or different, R is an organic radical bonded to the phosphorus via a carbon or oxygen atom, and a=2 or 3, with an organic compound of the formula S′ where A is as defined for the structural unit S, which comprises carrying out the reaction in the presence of at least one basic ion exchange resin.