Triphenylsulfonium Bromide

The Uses of Triphenylsulfonium Bromide

Triphenylsulfonium Bromide is used in the preparation of sulfonium salt photoacid generator for deep-UV microlithography.

Preparation

Triphenylsulfonium bromide synthesis: A 3.0 M solution of phenylmagnesium bromide in diethyl ether (50 ml, 0.15 mole) was distilled under vacuum with slow heating from 20° to 80°C. Benzene (40 ml) was added, followed by n-heptane (300 ml). The resulting mixture was stirred and a solution of diphenylsulfoxide 10.1 g, (0.050 mol), in benzene (60 ml) was added during 1 hour at 80°C. The mixture was stirred for 3 hours and cooled to room temperature. An 25% aqueous hydrobromic acid solution (180 ml) was slowly added to the reaction mixture (exotherm-). The layers were separated and the organic layer was extracted twice with 5% aqueous hydrobromic acid (2 x 30 ml). The combined aqueous extracts were extracted three times with dichloromethane (3×250 ml). The dichloromethane extracts were dried over magnesium sulfate, filtered and the organic solvent evaporated to leave triphenylsulfonium bromide (10.2 g, 60%), which was crystallized from dichloromethane/diethyl ether. M.p. 285-7°C.