ジオキサンリグニンの光酸化(2) 被光した6種のジオキサン-塩酸リグニンからのエーテル抽出成分

A study was carried out on photodegradation of lignins isolated from Hinoki wood (Chamaecyparis obtusa) using a dioxane-water medium containing hydrogen chloride as a solvent. In order to isolate lignins, wood meals were treated as follows: (1) successive extractions in increasing concentrations of 0.04, 0.08 and 0.24 equivalents of HCl/one liter of solvent medium (Lignin A, B and C): (2) further hydrolysis of each of the above lignins (Lignin a, b and c) (Fig. 1). All the lignins so isolated were studied with respect to their yields of ether extract before and after irradiation of light. Lignin a, b and c were decomposed by irradiation for 4 hours to produce ether extract enough to be detectable. In lignin A, B and C, ether extracts from lignins irradiated for 4 hours were not always larger than those from unexposed lignins in quantity (Table 1). The increase of ether extract was, however, observed in those lignins irradiated for 24 hours (Table 2). In lignin A, ether extracts were observed on samples obtained in the method as shown in Fig. 2 and were found to increase dy irradiation of light. Ether extracts from 6 kinds of lignin were developed by thin layer chromatography (TLC). Very similar chromatograms were observed from all of lignin (Fig. 3-1 and 3-2). Extracts from each chromatogram in the case of lignin a were measured (Table 3). Main products by irradiation were assumed to be acetoguaiacone, coniferyl aldehyde and acidic compounds by comparative TLC and color reactions