ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

A  CNDO/S3' study of lignin model quinone methides and related cations

S.G. Semenov and S.M. Shevchenko

Department of Quantum Chemistry, Leningrad University, SU-198 904 Leningrad

Abstract: The electronic structure and chemical reactivity of some typical lignin model p-hydroxybenzaldehydes and p-quinone methides as well as products of their protonization have been studied by means of the semiempirical CNDO/S3' method (corrected parameters were implemented). The results indicate a benzyl cation structure of protonated p-hydroxybenzaldehydes and p-quinone methides. Protonization drastically changes electron affinity and electronegativity of quinone methides, but not their hardness which is much lower than the hardness of related aldehydes. The calculations explain a pronounced regioselectivity of FMO-controlled reactions of quinone methides and corresponding cations.

Full paper in Portable Document Format: 453a289.pdf

Chemical Papers 45 (3) 289–297 (1991)