Wednesday, March 6, 2013

Bonus Process Wednesday: safety warning on Togni's reagent II

Annotated by CJ. Credit: Org. Process Res. Dev.
From Organic Process Research and Development, a safety warning on Togni's reagent II for trifluoromethylation [1]:
Togni’s reagent II (1-(trifluoromethyl)-1,2-benziodoxol-3(1H)-one, 1) is a versatile reagent for the nucleophilic introduction of trifluoromethyl groups. We have now found that this compound has explosive properties and would like to make the chemical community aware of this. The first hypervalent iodo intermediate in the synthesis of this reagent (1-hydroxy benz-1,2-iodoxol-(3H)3-one, 4) is also hazardous as well as probably the first Togni reagent (1,3-dihydro-3,3-dimethyl- 1-(trifluoromethyl)-1,2-benziodoxole, 2) (Scheme 1).
The authors performed a variety of DSC, impact and friction tests and found that Togni's reagent II was "highly explosive" in the Koenen test. 

1. Fiederling, N.; Haller, J.*; Schramm, H. "Notification about the Explosive Properties of Togni’s Reagent II and One of Its Precursors." Org. Process Res. Dev. ASAP, 


  1. the language of this letter is rather poor. they even claimed that Togni's reagent is nucleophlic cf3 in the first paragraph.

  2. Just spent my masters thesis investigating this compound. Good job I didn't scale up too far.