John L. Dektar

Novel photoinduced electron transfer reactions between naphthalene and triphenylsulphonium salts

Abstract Irradiation of solutions of naphthalene and triphenylsulphonium trifluoromethanesulphonate initiates an electron transfer reaction which gives 1- and 2-phenylnaphthalenes, 2- and 4-phenylthiobiphenyls, and diphenyl sulphide. The phenylnaphthalenes are formed by an in-cage reaction between phenyl radical and naphthalene radical cation, whereas diphenyl sulphide is an escape product. A second cage process, oxidation of diphenylsulphide by naphthalene radical cation, generates diphenylsulphinyl radical cation; reaction of this intermediate with phenyl radical gives the phenylthiobiphenyl isomers. However, irradiation of anthracene and triphenylsulphonium triflate yields only phenylated anthracenes and diphenylsulphide, because anthracene radical cation cannot oxidize diphenylsulphide.

A new mechanism for photodecomposition and acid formation from triphenylsulphonium salts

A new photodecomposition pathway for triphenylsulphonium salts yields phenylthiobiphenyls by a cage fragmentation–recombination process as major products, in addition to diphenyl sulphide; a new mechanism for acid formation is described.

Cationic Photoinitiators: Solid State Photochemistry of Triphenylsulfonium Salts

Abstract Triphenylsulfonium bromide, triflate, tetrafluoroborate, hexafluoroarsenate, hexafluorophosphate and hexafluoroantimonate were irradiate in solution and in the solid state. The photoproducts, 2-, 3- and 4-phenylthiobiophenyl are formed by an in-cage fragmentation-recombination mechanism, whereas diphenylsulfide is formed by a cage-escape reaction. In dilute solution, the ratio of cage to escape products is approximately one for each salt. Also in concentrated solutions, an identical cage : escape ratio is observed for all salts except for the bromide, which favors the escape reaction. Photolysis of the salts in the solid state shows remarkable counter ion dependence and cage : escape ratios as high as 5 : 1 are observed. The mechanism for both in-cage and escape reactions is described.