Method for producing bis-[4-(diphenylsulfonio)pheny] sulfide bis-M.X6 photoinitiator

Claim 1

In the method of making a photoinitiator, the steps comprising: A. forming a first reactant by admixing diphenyl sulfide and chlorine gas in an organic Friedel-Crafts solvent in the presence of a Friedel-Crafts catalyst to react the chlorine gas with the diphenyl sulfide and form bis-[4-(diphenylsulfonio) phenyl] sulfide dichloride as said first reactant, said chlorine gas being present in an amount of 0.7-1.4 moles per mole of diphenyl sulfide and said solvent being present in an amount of 2-10 parts by weight per part of said diphenyl sulfide, said reaction being conducted at ambient temperature or therebelow; B. adding water thereto to hydrolyze the reaction mixture; C. recovering said bis-[4-(diphenylsulfonio) phenyl] sulfide dichloride from said reaction mixture by extraction from the organic layer resulting from the hydrolysis; D. admixing said bis-[4-(diphenylsulfonio) phenyl] sulfide dichloride in an aqueous solution with a second reactant having the formula T·MF 6 wherein M is one of phosphorus, antimony or arsenic, T is hydrogen or a metal whose halide salt is water soluble, said reactants reacting to produce a precipitate substantially comprising bis-[4-(diphenylsulfonio) phenyl] sulfide bis-MF 6 , said second reactant being present in an amount of at least about 2 moles per mole of said solution providing about 0.5-2.0 moles water per mole of said second reactant, said reactants being admixed in said aqueous solution at a temperature of about 0°-50° C. for a period of time sufficient to permit said pecipitate to form; E. recovering said precipitate by separation from said solution; and F. drying said precipitate at a temperature below about 50° C. for at least an initial period to dewater said precipitate and recover a frangible product containing at least 50 percent by weight bis-[4-(diphenylsulfonio) phenyl] sulfide bis-MF 6 based upon solids.