Creosol and its methyl ether (4-methylveratrol), two simple model compounds representing phenolic and non-phenolic nuclei in lignins, were reacted in aqueous solution at ambient temperature and pressure with hydroxyl radicals generated by -radiolysis. The reactions were conducted at different pH levels (2-12) and in the presence and absence of oxygen. After fractionation of the reaction mixtures, more than 40 products from each model compound were identified by HPLC-UV, GC-MS and/or NMR analyses. In some cases the data were compared with those of corresponding authentic samples. On the basis of the composition of the reaction mixtures, the most important reaction modes were identified äs oxidative coupling, demethoxylation, hydroxylation and oxidation of the methyl group. Surprisingly, only small yields of ring opening products were found, even when the reactions were run in the presence of oxygen. The mechanisms of the observed types of reaction are discussed and the influence of pH and of oxygen on the product pattern and on the rate of Substrate consumption is tentatively interpreted.

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The reactions of three hydroxy-and/or rnethoxy-substituted stilbenes with hydroxyl radicals (HO·) or with hydroxyl radicals and Superoxide radicals (ΗΟ·+θ2 τ /ΗΟ 2 ·) under alkaline and acidic conditions have been studied. In this part, the course of cleavage of the conjugated double bond in the stilbenes is described. The preparation of the starting stilbenes and of a suggested intermediate using previously published methods with some modifications is also given.