Photochemical studies on a phenolic phenylcoumarone lignin model molecule in relation to the photodegradation of lignocellulosic materials. Part 2. Photophysical and photochemical studies

Autor: Alain Castellan, P. Fornier de Violet, C. Noutary, Joseph Vercauteren
Rok vydání: 1995
Předmět:
Zdroj: Research on Chemical Intermediates. 21:247-262
ISSN: 1568-5675
0922-6168
DOI: 10.1007/bf03052256
Popis: The structure of the photoproducts obtained by irradiation of a phenylcoumarone molecule PCO, model of the photodegradation of lignin, being established, the mechanism of their formation was approached by fluorescence and flash photolysis techniques, low temperature absorption spectroscopy in rigid matrix, and continuous irradiation in solution and in the solid state. Some evidence was given for the formation of a phenoxy radical leading either by oxidoreductive processes to the formation of a catechol IR3, or by coupling with the starting phenol to the generation of a cyclobutane radical dimer, prone to be transformed into stilbene phenoxy radical by retro “2π+2π” reaction. It was proposed that the oxidation of the latter could give the very coloured quinone methide IR1 or the α-carbonylstilbenol IR2. The singlet manifold appears to be the main pathway of the production of IR1, IR2 and IR3 which are formed in the presence of ground state oxygen.
Databáze: OpenAIRE
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