This study explores the valorization of Kraft lignin by conversion into nylon precursors in a two-step process. First, lignin was depolymerized in dilute alkaline aqueous solution under atmospheric N₂ at 200 °C to give guaiacol with high selectivity (>80%) with a total monomer production of 13% based on lignin input. Solution and solid state NMR analyses and reactions of model compounds indicated that depolymerization took place via cleavage of β-O-4 bonds in lignin. In the second step, lignin-derived guaiacol was selectively converted to the nylon precursors cyclohexanol/cyclohexanone (KA oil) using Ru/C catalyst under 1 bar H₂ and 150 °C. This two-step process constitutes a low-temperature and low-pressure pathway for producing value-added chemicals from lignin using water as the reaction solvent.

中文翻译：

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在温和条件下将牛皮纸木质素分两步转化为尼龙前体

这项研究探索了牛皮纸木质素在两步法中转化为尼龙前体的价值。首先，将木质素在200°C的大气压N ₂下于稀碱性水溶液中解聚，从而得到具有高选择性（> 80％）的愈创木酚，基于木质素输入量，总单体产量为13％。溶液和固态NMR分析以及模型化合物的反应表明，解聚反应是通过木质素中的β-O-4键断裂而发生的。在第二步中，使用Ru / C催化剂在1 bar H ₂下将木质素衍生的愈创木酚选择性转化为尼龙前体环己醇/环己酮（KA油）和150°C。这两个步骤的过程构成了低温和低压途径，用于使用水作为反应溶剂从木质素生产增值化学品。