Structural Analysis of Lignin by Pyrolysis-Gas Chromatography
Structural Analysis of Lignin by Pyrolysis-Gas Chromatography
复制标题
热解-气相色谱法分析木质素的结构
DOI：
10.2524/jtappij.49.735
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
A. Yamaguchi
中科院分区：
文献类型：
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作者：
Satoshi Suzuki;A. Izumi;H. Ohi;K. Kuroda;A. Yamaguchi
热解气相色谱 (Py-GC) 用于表征腐烂木材中的木质素。最近，Py-GC 成为分析合成聚合物的强大工具之一。使用 PyGC 可以快速分析极少量的固体材料。在木材中木质素的结构分析中，无需从木材中分离出木质素即可通过 Py-GC 进行分析。通过 Py-GC 分析杉木时，可以检测到 8 种主要的木质素热解产物（愈创木酚、4-甲基愈创木酚、4-乙烯基愈创木酚、香草醛、反式异丁子香酚二氢松柏醇、松柏醛和反式松柏醇）。云芝和沼泽酪霉菌热解产生的 8 种热解产物的产率低于完好木材。在云芝腐烂的杉木中，愈创木酚的峰面积与 8 种热解产物的组合峰面积 (cpaG) 的比值随着组合峰面积的减小而增大。另一方面，在被沼泽木霉腐烂的杉木的热解中，热解产物的峰面积与cpaG的比率和单位样品重量的cpaG之间没有发现明显的关系。山毛榉(Fagus crenata)木材也被水青冈、狄更斯、灵芝和沼泽木腐烂，并通过Py-GC进行了分析。所有腐烂的山毛榉木材显示四种主要紫丁香基类型化合物（丁香酚、4-甲基丁香酚、4-乙烯基丁香酚、反式-4-丙烯基丁香酚）（sumS）的组合峰面积与四种主要愈创木酚类化合物（愈创木酚、4-甲基愈创木酚、4-乙烯基愈创木酚、反式异丁子香酚）（sumG）的组合峰面积的比率小于健全的比率木头。这表明木质素的紫丁香基单元优先降解为愈创木基单元。在上述四种真菌腐烂的山毛榉木的热解中，愈创木酚与 sumG 的峰面积比以及丁香酚与 sumS 的峰面积比增加。为了澄清木质素结构令人信服的热解起源，以高产率产生丁香酚和愈创木酚，对一些木质素二聚体模型化合物进行了 Py-GC：丁香二醇-β-愈创木醚（SG-OH），脱氢二异丁香酚 (DDI) 和 α-愈创木氧基乙酰丁香酮 (SG=O)。苯香豆素型木质素模型化合物 DDI 不产生愈创木酚。类似地，丁香醇不是由 SG-OH 形成的，SG-OH 是在 Cα 位具有羟基的 β-O-4 类似物。另一方面，在Cα位具有羰基SG=O的β-O-4类似物通过Cα原子和芳香环之间的键的热解断裂得到丁香醇，产率为3mol%。这些结果表明，真菌处理在木质素大分子中形成α-羰基应该是腐烂木材的Py-GC中愈创木酚和丁香酚的比例增加的原因之一。 Py-GC 有望成为表征腐烂木材木质素的一种有前途的方法。
Pyrolysis-gas chromatography (Py-GC) was applied to the characterization of lignin in decayed woods. Recently, Py-GC becomes one of the powerful tools for analyses of synthetic polymers. Very small amounts of solid materials are analyzed rapidly by using PyGC. In the structural analysis of lignin in woods, lignin can be analyzed by Py-GC without being isolated from woods.When sugi (Ctyptomeria japonica) woods is analyzed by Py-GC, the eight main ligninderived pyrolysis products (guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, trans-isoeugenol dihydroconiferyl alcohol, coniferaldehyde and trans-coniferyl alcohol) can be detected. Pyrolysis of woods decayed by Coriolus versicolor and Tyromyces palustris provided the eight pyrolysis products in a smaller yield than that of the sound wood.In pyrolysis of sugi woods decayed by C. versicolor, the ratios of the peak area of guaiacol to the combined peak areas of the eight pyrolysis products (cpaG) increased with decreasing combined peak areas. On the other hand, in pyrolysis of sugi woods decayed by T. palustris, no cleas relationship was found between the ratios of the peak area of pyrolysis products to cpaG and cpaG per sample weight.Beech (Fagus crenata) woods were also decayed by C. versicolor, Daedalea dickinsii, Ganoderma lucidum and T. palustris, and analyzed by Py-GC. All decayed beech woods showed the smaller ratios of the combined peak areas of the four main syringyl type compounds (Syringol. 4-methylsyringol, 4-vinylsyringol, trans-4-propenylsyringol) (sumS) to the combined peak areas of the four main guaiacyl type compounds (guaiacol, 4-methylguaiacol, 4-vinylguaiacol, trans-isoeugenol) (sumG) than that of sound wood. This suggests that syringyl units of lignin were preferentially degraded to guaiacyl units. The ratios of the peak area of guaiacol to sumG and the ratios of the peak area of syringol to sumS increased in pyrolysis of beech woods decayed by the above four fungi.To clarify the convincing pyrolytic origins of the lignin structures giving syringol and guaiacol in high yields, some lignin dimer model compounds were subjected to Py-GC : syringlglycol-β-guaiacyl ether (SG-OH), dehydrodiisoeugenol (DDI) and α-guaiacoxyacetosyringone (SG=O). A phenylocoumaran type lignin model compound, DDI, did not give guaiacol. Similarly syringol was not formed from SG-OH, which is the β-O-4 analogue having a hydroxyl group at the Cα-position. On the other hand, the β-O-4 analogue having a carbonyl group at the Cα-position, SG=O, gave syringol by the pyrolytic cleavage of the bond between the Cα atom and aromatic ring in a 3 mol% yield. These findings suggest that the formation of α-carbonyl groups in the lignin macromolecule by fungal treatments should be one of the reasons why the ratios of guaiacol and syringol increased in Py-GC of the decayed woods. Py-GC is expected to be a promising method for characterization of the decayed wood lignin.