AN NMR-STUDY OF THE EQUILIBRIA INVOLVED WITH BENZOTRIAZOLE, CARBONYL-COMPOUNDS, AND THEIR ADDUCTS

A 1H and 13C NMR study of the equilibrium mixtures of benzotriazole and several carbonyl compounds with their adducts, in [ 2H6]benzene and other solvents, affords the equilibrium constants for the reversible formation of N-1 (K1) and N-2 (K 2) isomeric adducts. Thermodynamic parameters have been computed. Adduct formation is generally less predominant in sterically crowded cases. In general the N-1 isomer predominates over the N-2 isomer, however, with the sterically hindered 4,7-dimethylbenzotriazole this order is reversed.