Hydrogen abstraction from H-donor substrates by the 6-CF3-benzotriazol-N-oxyl radical (TFNO)

The aminoxyl radical 6-trifluoromethyl-benzotriazol-N-oxyl (TFNO) has been generated from the parent hydroxylamine 6-CF3-1-hydroxy-benzotriazole (TFBT) by one-electron oxidation with a CeIV salt and characterized by spectrophotometry and cyclic voltammetry (CV). Rate constants of H-abstraction (kH) by TFNO from a number of H-donor benzylic substrates have been determined spectrophotometrically in MeCN solution at 25 -C. A radical H-atom transfer (HAT) route of oxidation is substantiated for TFNO by several pieces of evidence. The kinetic data also testify the relevance of stereoelectronic effects upon the HAT reactivity of TFNO.