Abstract The formation and the destruction of an intermediate involved in the Beckmann rearrangement of 2, 4, 6-trimethylacetophenone oxime have been studied in concentrated trifluoromethanesulfonic acid by kinetic and spectroscopic measurements. Observed (k obs) and thermodynamic rate constants (ko) have been estimated and the values compared with the ones obtained in perchloric, sulfuric, and methanesulfonic acids. In the range 80–100 ...