m-(Trifluoromethyl) phenyl) bromodiazirine, 10, reacts with 16N terminally labeled sodium azide in dimethyl sulfoxide to give m-(trifluoromethy1) benzonitrile which, in all cases, contains I5N incorporation. The largest amount of label incorporation (42%), and the fastest rate, is observed when the reaction is carried out in room light. The smallest amount of label incorporation (ll%), and the slowest reaction, is observed when the reaction is carried out ...