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首页> 外文期刊>Journal of Wood Chemistry and Technology >THE CHARACTERISTICS AND REACTIVITY OF ACID-LABILE ARYL ETHER UNITS IN WOOD LIGNIN
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THE CHARACTERISTICS AND REACTIVITY OF ACID-LABILE ARYL ETHER UNITS IN WOOD LIGNIN

机译：木质素酸酸芳烃醚单元的特征和反应活性

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摘要

Wood lignin contains significant amounts of acid-labile aryl ether units, which play a significant role in lignin modification or delignification processes. We have evaluated the rate and reaction kinetics on the acid-catalyzed cleavages of aryl ether structures for wood lignin in situ based on the formation of phenolic hydroxyl groups. The content of acid-labile aryl ether units was quite uniform for a variety of softwood wood lignins (similar to 4% per C-9 unit) and it varied appreciably among hardwood species, ranging from 4% for aspen to 9% for beech wood lignin. These variations, however, appear to be related to the content of syringyl units in wood lignin. The reactivity of these reactive aryl ether structures was noticeably higher for the spruce than for the aspen wood lignin. This difference in reactivity, based on the behavior of lignin model compound reactions, can be attributed to the influence of syringyl moieties in aspen wood lignin. It appears that most of the acid-labile aryl ether units in hardwood were associated with the syringy moiety being present as a benzyl unit, which is much less reactive than the corresponding guaiacyl moiety.
机译：木木质素包含大量的酸不稳定芳基醚单元，它们在木质素修饰或脱木质素过程中起重要作用。我们已经基于酚羟基的形成，评估了木质素原位催化酸催化芳基醚结构裂解木质素的速率和反应动力学。酸软性芳基醚单元的含量对于各种软木木质素均相当均匀（每C-9单元约为4％），并且在硬木树种中变化明显，从白杨木的4％到山毛榉木的9％不等。木质素。然而，这些变化似乎与木木质素中丁香基单元的含量有关。对于云杉而言，这些反应性芳基醚结构的反应性明显高于白杨木木质素。基于木质素模型化合物反应行为的反应性差异可归因于白杨木木质素中丁香基部分的影响。看来，硬木中大多数对酸不稳定的芳基醚单元都与以苄基单元形式存在的丁香基部分有关，该丁香基部分的反应性比相应的愈创木基部分低得多。

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