慈竹、毛竹木质素的化学官能团和化学键特征研究

Functional groups and chemical bonds of lignin of Neosinocalamus affinis and Phyllostachys pubescens

用有机元素分析、红外光谱仪(FTIR)、核磁共振波谱仪(1H-NMR)研究了从慈竹和毛竹的竹青、竹黄中提取的4种磨木木质素的结构特征。结果表明:4种磨木木质素具有不同的C9经验式,但均主要由愈创木基、紫丁香基和对羟苯基3种芳香环结构组成,符合禾本植物木质素的结构特征。在毛竹的磨木木质素中未发现归属愈创木基环加CO伸缩振动的特征峰。在2种竹材的竹黄磨木木质素中未发现在仲醇中的C—O变形和脂肪醚特征峰。慈竹竹青与竹黄磨木木质素中脂肪族羟基(OHaliph)和游离酚羟基(OHph)占总羟基数的比例存在较大的差异;慈竹竹黄的磨木木质素中OHaliph含量较高,而OHph含量较低。毛竹竹青与竹黄磨木木质素中OHaliph和OHph占总羟基数的比例基本相同。慈竹的2种磨木木质素结构单元主要由β-O-4键和β-1键2种化学键构成,毛竹磨木木质素结构单元主要由β-O-4键、β-5键和β-1键3种化学键构成,未检测出β-β键型结构。

The chemical structures of four milled wood lignins（MWLs）,prepared from the inner and outer parts of the stems of Neosinocalamus affinis and Phyllostachys pubescens,were examined by elemental analysis,FTIR and 1H-NMR spectroscopy.The results indicated that the average per-C9-unit formulae of the four MWLs were different,but were largely composed of guaiacyl（G）,syringyl（S） and p-hydroxyphenyl（H） units which are similar to the structural characteristics of grass lignin.The peak assigned to the G ring plus C==O stretching was not found in the IR spectrum of the MWLs of P.pubescens.The peak assigned to the C—O deformation in secondary alcohols and aliphatic ethers was not found in the IR spectrum of MWLs from the inner parts of either N.affinis or P.pubescens.The proportions of aliphatic（OHaliph） and free phenolic hydroxyl（OHph） in total hydroxyl were different for MWLs from both inner and outer parts of N.affinis,with more OHaliphand less OHphin the inner parts.In contrast,the contents of OHaliphand OHphin the outer parts were similar to those in the inner parts of P.pubescens.The main types of linkages in MWLs of N.affinis were β-O-4 and β-1 linkages,while in P.pubescens the main types were β-O-4,β-5 and β-1 linkages.The β-β linkage was not detected in the MWLs of either N.affinis or P.pubescens.