Patent ID: 8357822

Claim:
A process for producing a chlorophosphite, comprising: a first step of allowing phosphorus trichloride and a phosphorous acid triester represented by (RO) 3 P (wherein R denotes an alkyl group, a substituted alkyl group, a phenyl group or a substituted phenyl group) to react in the presence of a catalyst having a viscosity at 80° C. of 100 mPa·s or lower to produce a reaction liquid containing a chlorophosphite represented by RO(R′)PCl (wherein R is the same as defined above, and R′ denotes RO or a chlorine atom); and a second step of vaporizing the reaction liquid containing the chlorophosphite obtained in the first step to separate the catalyst, wherein the catalyst is a quaternary ammonium salt or quaternary phosphonium salt which is a liquid at 80° C.