木质素模型物的合成及其结构表征

发布时间：2018-08-20 17:20

【摘要】：木质素是构成植物骨架的主要成分之一,也是自然界中储量最丰富的含芳香环天然高分子聚合物,约占植物组分含量的15%～30%。木质素可转化为化学品及功能材料,具有具大的应用潜力,但木质素自身结构的复杂性和多样性使得木质素的高值转化及利用存在较大困难,因此基于木质素模型化合物合成解译木质素大分子结构对其高值转化及利用具有重要的研究意义。以单体化合物4-羟基-3-甲氧基苯乙酮为原料经多步化学反应合成了木质素大分子中含量最多的β-O-4型二聚体木质素模型物,并对其结构进行了表征。紫外光谱(UV)的最大特征吸收峰出现在280 nm,而红外光谱(FT-IR)证明了模型物中醚键的生成,一维及二维核磁共振光谱(NMR)确定合成产物的结构与目标化合物-致。采用化学/生物法合成了具有代表意义的β-5型二聚体木质素模型物,酯化后阿魏酸经过氧化物酶催化自由基反应得到该模型物。紫外光谱(UV)的最大特征吸收峰在330 nm,表明阿魏酸(酯)存在该模型物中,利用核磁共振光谱(NMR)确定合成产物的结构与目标化合物一致。为了对比模型物与真实木质素大分子结构上的差异,利用乙醇自催化法提取了落叶松和杨木的有机溶剂木质素,并对其结构进行了表征。紫外光谱(UV)表明杨木有机溶剂木质素特征吸收峰出现在274nm,而落叶松有机溶剂木质素特征吸收峰出现在280和330 nm处,274/280 nm处的吸收源自愈创木基(G型)或是紫丁香基(S型)木质素结构非共轭的芳环吸收,而330 nm位置的吸收峰来自于阿魏酸结构。红外光谱(FT-IR)表明阔叶木主要含愈创木基(G型)和紫丁香基(S型)木质素,针叶木主要含愈创木基(G型)木质素。核磁共振光谱(NMR)结果表明所合成的β-O-4型和β-5型木质素模型物均存在于有机溶剂木质素中,说明木质素模型物可以帮助解译木质素大分子真实结构。
[Abstract]:Lignin is one of the main components of plant skeleton, and it is also the most abundant natural polymer containing aromatic ring in nature, accounting for about 15% of plant component. Lignin can be converted into chemicals and functional materials, which has great potential for application. However, the complexity and diversity of lignin structure make it difficult to convert and utilize lignin at high value. Therefore, the synthesis and interpretation of lignin macromolecular structures based on lignin model compounds are of great significance for their high value conversion and utilization. The 尾 -O-4 type lignin model compound with the largest content in lignin macromolecule was synthesized from the monomer compound 4-hydroxy-3-methoxyacetophenone by multi-step chemical reaction, and its structure was characterized. The maximum characteristic absorption peak of UV (UV) appears at 280nm, and the formation of ether bond in the model is proved by infrared spectroscopy (FT-IR). The structure and target compound of the synthesized product are determined by 1D and 2D NMR (NMR). The 尾 -5 dimer lignin model material was synthesized by chemical / biological method. The model was prepared by peroxidase catalyzed free radical reaction of ferulic acid after esterification. The maximum characteristic absorption peak of UV (UV) is 330nm, indicating that ferulic acid (ester) exists in the model, and the structure of the synthesized product is consistent with the target compound determined by NMR (NMR). In order to compare the structural differences between the model and the real lignin, the organic solvent lignin of Larix gmelini and poplar was extracted by ethanol autocatalytic method, and its structure was characterized. UV (UV) showed that the characteristic absorption peak of lignin in poplar organic solvent appeared at 274nm, while that of larch organic solvent lignin appeared at 280nm and 330nm from guaiacyl group (G type) or lilac group. (S-type) absorption of aromatic rings with (S-type) lignin structure unconjugated, The absorption peak at 330 nm is derived from ferulic acid structure. Infrared spectroscopy (FT-IR) showed that broad leaved wood mainly contained guaiacol (G type) and syringe (S type) lignin, and coniferous wood mainly contained guaiacol (G type) lignin. The (NMR) results showed that both 尾 -O-4 and 尾 -5 lignin models existed in the organic solvent lignin, indicating that the lignin model compounds could help to interpret the real structure of lignin macromolecules.
【学位授予单位】：北京林业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：O636.2

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