Halonium salts

For some applications, for example curing of epoxy resins, the in situ generation of cationic initiators is required. This may be achieved by photochemical decomposition of suitable promotors to radicals, which in the presence of diazonium, sulfonium, or halonium salts (not able to initiate the polymerization by itself) are converted into corresponding cationic initiators [45-48]. 

Sulfonium Salts. Other onium salts beside the diazonium and halonium salts will, on exposure to light, initiate polymerization of epoxides and other monomers capable of undergoing cationic polymerization. The use of onium salts of the elements of Groups Va and Via was first described in 1975 (41, ) and 1976 ( ). 

A similar reaction consists of decomposition of the double salt of a diphenyl-halonium salt and a heavy-metal halide by a powdered metal (Reutow). It can be used for synthesis of aryl derivatives of a wide variety of metals such as mercury, tin, antimony, and bismuth.23... 

The other halonium salts were prepared by the procedure of Olah... 

---