Abstract The most common non-phenolic β-O-4-type lignin model compounds with or without the γ-hydroxymethyl group (C6-C3- or C6-C2-type, respectively) were treated in a 0.5 mol/L potassium tert-butoxide in DMSO solution at 30 °C to examine the effects of presence of the group. The β-O-4 bond of the C6-C3-type cleaved more rapidly than the C6-C2-type, indicating that the γ-hydroxy group contributes to the cleavage, in contrast to their reactions in alkaline pulping processes. Furthermore, the β-O-4 bond of the threo isomer of the C6-C3-type cleaved more rapidly than that of the erythro isomer. This result can be attributed to the fact that the erythro isomer has the hydrogen bond between a generated alkoxide and the other hydroxy group at its α- and γ-positions in its most-preferential conformer, interfering with the β-O-4 bond cleavage. It was also suggested in treatments of their methyl-etherified derivatives at the α- or γ-hydroxy group that the contribution of the γ-hydroxy group of the threo isomer is greater than that of the erythro isomer. Detailed examination of the distribution profile of reaction products supported this greater contribution of the γ-hydroxy group of the threo isomer.

中文翻译：

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在使用叔丁醇的碱性系统中，γ-羟基对木质素模型化合物的 β-O-4 键断裂的贡献

摘要 最常见的非酚类 β-O-4 型木质素模型化合物有或没有 γ-羟甲基（分别为 C6-C3- 或 C6-C2-型）在 0.5 mol/L 叔钾中处理。在 30 °C 下将丁醇溶于 DMSO 溶液中，以检查该基团存在的影响。C6-C3 型的 β-O-4 键比 C6-C2 型裂解得更快，表明 γ-羟基有助于裂解，这与它们在碱性制浆过程中的反应相反。此外，C6-C3 型苏式异构体的 β-O-4 键比赤式异构体裂解得更快。这一结果可归因于这样一个事实，即赤型异构体在其最优先的构象异构体的 α- 和 γ- 位上具有生成的醇盐和另一个羟基之间的氢键，干扰了 β-O-4 键的断裂. 在α-或γ-羟基处的甲基醚化衍生物的处理中还表明，苏式异构体的γ-羟基的贡献大于赤式异构体的贡献。对反应产物分布曲线的详细检查支持了苏式异构体的 γ-羟基的这种更大贡献。