Safety Warning: Togni’s Reagents

Some of you may have used the second Togni reagent (shown) as a trifluoromethylating agent. Well, there’s a new paper in Organic Process R&D that brings word that it’s an explosive hazard. A group at Novasep, in Leverkusen, Germany finds that it has a powerful exothermic decomposition, and (in addition) it’s about as combustible as black powder. Sensitivity to impact and friction varied from sample to sample as well, which isn’t what you want to hear, either. Their conclusion is that the reagent is “dangerously explosive and may only be transported by approval of the national competent authority.” The first Togni reagent (with a dimethyl in place of the carbonyl) wasn’t fully evaluated, but it may be just as bad. That one has been available from Aldrich; I imagine that this may change shortly. Too bad – these are useful reagents, but not if you have to suit up to use them safely.