STRUCTURAL CHARACTERIZATION OF ALKALI-EXTRACTABLE BAMBOO LIGNIN: AN NMR PRESPECTIVE
This research investigated the physicochemical properties and structural characterizations of seven alkali-extractable lignin preparations by a two-step isolation method from bamboo. The lignin preparations were analyzed by GPC to determine average molecular weights, and further characterized by 13C and HSQC NMR spectroscopy. The most striking characteristics of these lignin preparations are their low average molecular weights (770-1890 g mol-1). It also revealed that these lignin preparations contained considerable amounts of esterified p-coumaric acid, which cannot be completely hydrolyzed under the conditions given. Moreover, semi-quantitative HSQC-NMR showed that a dominant amount of β-O-4′ linkages (about 70％) and resinol substructures (β-β′, 19％) together with small amounts of phenylcoumaran substructures (β-5′) were identified to be involved in the lignin preparation (NaOH extractable). Furthermore, the results revealed that these lignin preparations belonged to HGS-type lignin, and contained slightly more amounts of syringyl units than guaiacyl units. From S/G ratios, it also implied that non-condensed syringyl units were more liable to release than the guaiacyl units from the cell wall under the mildly alkaline condition.
alkali-extractable lignin β-O-4′ HSQC GPC 13C-NMR
Wen Jialong Sun Yongchang Sun Shaoni Xu Feng Sun Runcang
Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing, 100083, China Co Institute of Biomass Chemistry and Technology,Beijing Forestry University, Beijing, 100083, China
国际会议
广州
英文
352-355
2010-11-08（万方平台首次上网日期，不代表论文的发表时间）