The depolymerization of kraft lignin with a copper–vanadium hydrotalcite-like catalyst (HTc-Cu-V) and V(acac)₃/Cu(NO₃)₂·3H₂O mixtures to monomeric aromatic aldehydes and aromatic acids such as vanillin and vanillic acid using molecular oxygen as oxidant is reported. The obtained products correlate to model-based studies with erythro-1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)-1,3-propanediol (1a). Kinetic investigations with 1a demonstrate that there is a combined effect of V(acac)₃ together with Cu(NO₃)₂·3H₂O that enhances the catalytic activity and increases the selectivity and yield for the cleavage products veratric acid and veratraldehyde. Veratric acid is formed through reaction pathways involving either the transient oxidation products 1-(3,4-dimethoxyphenyl)-3-hydroxy-2-(2-methoxyphenoxy)propan-1-one (2) and 1-(3,4-dimethoxyphenyl)-2-(2-methoxyphenoxy)prop-2-en-1-one (5) or through overoxidation of veratraldehyde. The formation of veratraldehyde likely proceeds through C–C bond cleavage involving either a retro-aldol or a single electron transfer mechanism.

中文翻译：

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木质素β-O-4连锁反应的催化裂解机理研究：对香兰素和香草酸形成的意义。

用铜钒水滑石样催化剂（HTc-Cu-V）和V（acac）₃ / Cu（NO ₃）₂ ·3H ₂ O混合物将牛皮纸木质素解聚为单体芳香醛和芳香酸，如香兰素和报道了使用分子氧作为氧化剂的香草酸。获得的产物与基于赤型-1-（3,4-二甲氧基苯基）-2-（2-甲氧基苯氧基）-1,3-丙二醇（1a）的基于模型的研究相关。用1a进行的动力学研究表明，V（acac）₃与Cu（NO ₃）₂ ·3H _{2共同作用}O提高了催化活性，并增加了裂解产物veratric acid和veratraldehyde的选择性和收率。通过与瞬态氧化产物1-（3,4-二甲氧基苯基）-3-羟基-2-（2-甲氧基苯氧基）丙烷-1-酮（2）和1-（3,4-二甲氧基苯基）-2-（2-甲氧基苯氧基）丙-2-烯-1-酮（5）或通过四乙醛的过度氧化。藜芦醛的形成可能通过涉及逆向羟醛或单个电子转移机制的C–C键断裂而进行。