Abstract We succeeded to observe at low temperature in reactions of trifluoromethanesulfonic anhydride and trifluoromethanesulfonyl chloride with hydrazine, phenyl hydrazine, and 1, 1-dimethylhydrazine a formation of the corresponding trifluoromethanesulfonic hydrazides that at heating to room temperature decomposed liberating nitrogen and affording trifluoromethanesulfinic acid. 2-Phenyl-2 H-1, 2, 3- ...