Insertion reactions of trifluoromethylcarbene

Abstract

Trifluoromethylcarbene, generated photolytically from 2,2,2-trifluorodiazoethane, reacts with the C–H bonds of saturated hydrocarbons in the liquid phase to give high yields of the corresponding insertion products. The primary and secondary C–H bonds in n-butane undergo insertion at essentially the same rate, but the tertiary C–H bond in isobutane is some 30% more reactive than the primary C–H. In the vapour phase very low yields of insertion product result, and 1,1,1-trifluoroethane and trifluoroethylene are also produced. Liquid-phase photolysis in trimethylsilane gives more rapid insertion into Si–H than into C–H bonds. The mechanistic implications of the results are discussed.