A safety warning on Togni’s reagents

From Novasep in Germany and Organic Process Research and Development comes word that Togni’s reagent II, used for trifluoromethylations, is explosive. Also highly hazardous is an intermediate in the reagent’s synthesis and probably Togni’s reagent I.

Togni’s reagent II, in particular, shows some properties comparable to trinitrotoluene and gunpowder. Caution the paper’s authors:

  • Work with the compounds behind a safety shield and use small amounts
  • Avoid open flames and sparking
  • Don’t grind the materials with “brute force” (I think I’d probably err on the side of not grinding at all)
  • Use “soft and polished tools” for manipulations
  • Avoid caking and disperse lumps early
  • Impurities may influence the thermal and mechanical sensitivity of the material

The Sigma-Aldrich material safety data sheet for Togni’s reagent II, 1-(trifluoromethyl-1,2-benziodoxol-3(1H)-one, mixed with diatomaceous earth classifies the product only as an irritant and toxic. Togni’s reagent I, 3,3-dimethyl-1-trifluoromethyl-1,2-benziodoxole, is flagged as an irritant.

Hat tip to Chemjobber for the heads up, In the Pipeline also has discussion
Org. Process Res. Dev., DOI: 10.1021/op400035b

Author: Jyllian Kemsley

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  1. Department of Transportation regulations require certain testing in order to ship materials. If a material is found to be explosive it can only be shipped special. Special shipping costs big money. I am certain that Aldrich found the neat material to be somewhere between an explosive and a deflagrator so the material was mixed with an inert agent to bring down the energy of its exotherm per unit of mass. This way it could be shipped safely under normal shipping regulations. With Aldrich selling it as a 50/50 mixture I would guess it’s dangerous nature has been known for a while.