Abstract

The relative stabilities of the two tautomers of benzotriazole have been an issue of considerable interest, and have been studied extensively both experimentally and theoretically. Their stability is related to such fundamental properties as the aromaticity of heterocycles and the extent of lone pair repulsions. Early computational and experimental work indicated that the less symmetrical (C point group symmetry) 1H-tautomer is the more stable. [ 1 ] Crystal structure measurements showed that the solid state exists almost exclusively as the IH-tautomer.[2] Similarly, mass spectrometric studies showed the 1 H-tautomer to be predominant in the gas phase. [3] Without exception the electronic spectroscopy of benzotriazole in a range of solvents was found to be consistent with the 1H-tautomer.[4]

© 1996 Optical Society of America