Wang Yupeng, Hou Yucui, Li He, Wu Weize, Ren Shuhang, Li Jianwei
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China.
Department of Chemistry, Taiyuan Normal University, Jinzhong, Shanxi 030619, China.
ACS Omega. 2022 May 24;7(22):18861-18869. doi: 10.1021/acsomega.2c01812. eCollection 2022 Jun 7.
Lignin is a natural aromatic compound in plants. Several lignin structural models have been proposed in the past years, but all the models cannot be converted to benzene carboxylic acids (BCAs) for all aromatic rings connected to oxygen. This inspired us to explore the structures of lignin. Based on the yields of BCAs, the results of C NMR and ethanolysis residues, and gas chromatography-mass spectrometry and electrospray ionization mass spectrometry of ethanolysis of lignin, we have constructed a structural model of lignin with a formula CHONS. The model not only satisfies the results of analyses, but also explains the generation of BCAs from lignin oxidation and the ethanolysis products. Importantly, double-ring and triple-ring aromatic clusters are found in lignin, and some of them are connected by alkyl bridges, which results in conventional low conversions of lignin. Our findings in the structures of lignin may significantly influence the structures and applications of lignin.
木质素是植物中的一种天然芳香族化合物。在过去几年中已经提出了几种木质素结构模型，但所有模型都无法将与氧相连的所有芳香环转化为苯羧酸（BCA）。这激发了我们对木质素结构的探索。基于BCA的产率、碳核磁共振（C NMR）和乙醇解残渣的结果，以及木质素乙醇解的气相色谱-质谱联用（GC-MS）和电喷雾电离质谱（ESI-MS），我们构建了一个分子式为CHONS的木质素结构模型。该模型不仅符合分析结果，还解释了木质素氧化生成BCA以及乙醇解产物的情况。重要的是，在木质素中发现了双环和三环芳香族簇，其中一些通过烷基桥相连，这导致了木质素常规的低转化率。我们对木质素结构的研究结果可能会对木质素的结构和应用产生重大影响。
