Abstract Vanillin and acetovanillone are typical primary pyrolysis products of β O 4 lignin dimers, but the thermal reactions have not yet been elucidated. Data on their thermal reactivity and secondary pyrolysis pathway was studied via in-situ FTIR within a tube furnace reactor system. The result showed that pyrolysis breakdown products spanned four categories: gas, char, monomers, and polymers and secondary reaction products were polymers and char from re-polymerization and carbonization. In general, vanillin showed higher reactivity than acetovanillone. The removal of the CHO group in vanillin was first observed at 400 °C, to present a thermal reaction similar with guaiacol at higher temperatures. The reactivity of the COCH3 group in acetovanillone was low during the pyrolysis process in which radical-induced rearrangement of the aryl OCH3 group into the aryl CH3 group initially occurred as the major side-chain-conversion reaction. Finally, side-chain-conversion also included aryl demethylation or demethoxylation, tautomerism of COCH3, and cyclization between aryl OCH3 and OH group but at low reaction degrees.

中文翻译：

---

通过两种代表性单体模拟木质素的热解行为：香草醛和乙酰香草酮

摘要 香兰素和乙酰香兰素是βO 4 木质素二聚体的典型初级热解产物，但其热反应尚未阐明。通过管式炉反应器系统内的原位 FTIR 研究了它们的热反应性和二次热解途径的数据。结果表明，热解分解产物跨越四类：气体、焦炭、单体和聚合物，二次反应产物是再聚合和碳化产生的聚合物和焦炭。一般来说，香兰素比乙酰香兰素表现出更高的反应性。香草醛中 CHO 基团的去除首先在 400 °C 下观察到，在更高的温度下呈现与愈创木酚相似的热反应。乙酰香兰素中 COCH3 基团的反应性在热解过程中较低，其中自由基诱导的芳基 OCH3 基团重排为芳基 CH3 基团最初发生作为主要的侧链转化反应。最后，侧链转化还包括芳基去甲基化或去甲氧基化、COCH3 的互变异构以及芳基 OCH3 与 OH 基团之间的环化，但反应程度较低。