SIGNIFICANCE OF SIDE CHAIN OXIDATION IN THE REACTION OF β-O-4 TYPE LIGNIN MODEL COMPOUNDS WITH ACTIVE OXYGEN SPECIES UNDER OXYGEN BLEACHING CONDITIONS
The purpose of this research is to prove that not only phenolic but also non-phenolic units in lignin can be extensively oxidized under oxygen bleaching conditions. A dimeric β-O-4 type lignin model compound without phenolic aromatic ring, 2-(3,5-difiuorophenoxy)-l-(3,4dimethoxyphenyl)propane-l,3-diol (VDF) or 2-(2methoxyphenoxy)-1 -(3,4-dimethoxyphenyl)propane-1,3-di ol (VG), was treated together with a phenolic compound, 4-hydroxy3-methoxybenzyl alcohol (VA), under oxygen bleaching conditions. VA reacts with molecular oxygen and generates active oxygen spices (AOS). The attack of AOS on VDF or VG can result in the βO-4 bond cleavage and the liberation of 3,5-difluorophenol (DFPh) or 2-methoxyphenol, respectively. The detection of these compounds can confirm the conversion of the non-phenolic into phenolic moiety. The amount of DFPh accompanying the oxidative degradation of VDF was larger in treatments together with VA than those without VA, which confirmed the possible occurrence of the conversion of non-phenolic into phenolic lignin moieties and suggested the participation of AOS in the conversion. VG showed a similar result, which indicats that the fluoride groups in VDF do not largely affect its reaction with AOS. Several other dimeric model compounds were treated together with VA to examine the effect of the presence and kind of hydroxyl group on their reactions with AOS.
active oxygen species bleaching lignin non-phenolic aromatic ring phenolic aromatic ring
Satoshi Ohmura Tomoya Yokoyama Yuji Matsumoto
Laboratory of Wood Chemistry, Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
国际会议
16th International Symposium on Wood,Fiber and Pulping Chemistry(第十六届木材、纤维及制浆化学国际会议)
天津
英文
327-332
2011-06-08（万方平台首次上网日期，不代表论文的发表时间）