Revisiting alkaline nitrobenzene oxidation: quantitative evaluation of biphenyl structures in cedar wood lignin (Cryptomeria japonica) by a modified nitrobenzene oxidation method
Revisiting alkaline nitrobenzene oxidation: quantitative evaluation of biphenyl structures in cedar wood lignin (Cryptomeria japonica) by a modified nitrobenzene oxidation method
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DOI：
10.1515/hf-2014-0153
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发表时间：
2015-10-01
期刊：
影响因子：
2.4
通讯作者：
Matsumoto, Yuji
中科院分区：
文献类型：
--
作者：
Tannai, Akari;Goto, Haruka;Matsumoto, Yuji
建立了一种改进的碱性硝基苯氧化法（NBO），用于分析雪松木木质素中的联苯结构。该方法的最重要的一点是在吡啶中的改进后处理过程和甲硅烷基化产物的长时间气相色谱分析。将此方法应用于雪松木粉中，检测到一种新的联苯产物脱氢香草醛-香草酸（1-羧基-1 '-甲酰基-4，4'-二羟基-3，3 '-二甲氧基-5，5'-联苯），以及已知产物脱氢二香草醛和脱氢二香草酸。NBO在170 ℃下反应2-4 h时联苯产物的总收率最高。对后处理程序进行了轻微修改，以便可以对联苯产物进行定量。还用联苯型木质素模型化合物检查了木质素的联苯键的NBO转化率，并且这产生了75%的联苯型NBO降解产物。在相同条件下，以非缩合型β-O-4模型化合物为原料，香草醛和香草酸（VA）的总收率为89%。由于后者没有表现出任何联苯产物的峰，因此可以得出结论，通过NBO（0.17 mmol g（-1））获得的所有联苯产物均来自天然木材的木质素。据计算，即使不考虑NBO转化率，雪松木质素的100个苯丙素单元中至少有6.7个参与联苯结构。介绍了11种木质素模型化合物的合成和分析数据。
A modified alkaline nitrobenzene oxidation (NBO) method was developed to enable the analysis of the biphenyl structures of cedar wood lignin. The most essential point of the process is a modified work-up process in pyridine and a prolonged gas chromatography analysis of the silylated products. By applying this mean to cedar wood meal, a novel biphenyl product, dehydrovanillin-vanillic acid (1-carboxy-1'-formyl-4,4'-dihydroxy-3,3'-dimethoxy5,5'-biphenyl), was detected together with known products, dehydrodivanillin and dehydrodivanillic acid. The highest total yield of biphenyl products was detected when NBO was carried out for 2-4 h at 170 degrees C. The workup procedure was slightly modified so that the biphenyl products can be quantified. The NBO conversion rates of biphenyl linkages of lignin were also examined with a biphenyl-type lignin model compound, and this gave rise to 75% biphenyl-type NBO degradation products. Under the same condition, the total yield of vanillin and vanillic acid (VA) from a non-condensed-type beta-O-4 model compound was 89%. Because the latter did not exhibit any peak of the biphenyl products, it can be concluded that all the biphenyl products obtained by NBO (0.17 mmol g(-1)) were from the lignin of the native wood. It was calculated that at least 6.7 of 100 phenylpropanoid units of cedar lignin were involved in biphenyl structures even if the NBO conversion rate was not taken into consideration. The synthesis and analytical data of 11 lignin model compounds is described.