Bis(trifluoroacetoxy)borane is useful as a selective reducing agent, especially in the presence of strong acids.
The Preparative Method of Bis(trifluoroacetoxy)borane involves the treatment of certain complexes of borane, such as Borane-Tetrahydrofuran, Borane-Dimethyl Sulfide, or Borane-Pyridine, with Trifluoroacetic Acid in a suitable solvent such as tetrahydrofuran (THF), dichloromethane, or trifluoroacetic acid. Excess trifluoroacetic acid can be present because the title reagent is stable to protonolysis of the B-H bond.
Generated and employed in situ; normally not isolated and stored. Hydrogen is evolved during reagent generation. The reagent causes the cleavage and oligomerization of THF. Thus, the use of borane-THF for reagent generation, or the use of THF as solvent, is not recommended for reactions at temperatures above 25 °C. Use in a fume hood.
