文档介绍：第三节 木素的化学构造 Chapter 3 Chemical structure of lignin
木素的功能基
木素的结构单元
木素结构单元间的联接
光谱的基本概念及其在木素结构研究上的应用
木素模型构造图
木素-碳水化合物复合体（Le to o-quinone structures with the release of 1M methanol from each phenolic unit ()
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Fig.
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How to analyze the phenolic hydroxyl groups (continued)?
The aminolysis is based on the finding that phenolic acetates are cleaved with pyrrolidine(吡咯烷）much faster than aliphatic acetates. The pyrrolidine acetates formed in the reaction of an acetylated lignin is determined by GC (gas chromatography) ()
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How to analyze the aliphatic hydroxyl groups?
The total amount of hydroxyl groups in a lignin preparation can be determined by acetylation with acetic anhydride and pyridine followed by hydrolysis of the acetate and titration of the liberated acetic acid with a standard sodium hydroxide aliphatic hydroxyl content is determined by subtraction of the phenolichydroxyl content from the total hydroxyl content of the lignin.
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（三）羰基（carbonyl group）
存在于木素单元的侧链上，分为共轭羰基和非
共轭羰基。
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羰基的测定
全羰基可以通过硼氢化钠还原来测定。
共轭羰基可以通过还原示差紫外吸收光谱法定量。
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How to analyze the carbonyl groups?
An early method for the determination of the carbonyl content of lignin preparations is based on the use of hydroxyl carbonyl group reacts with hydroxyl amine hydrochloride forming an oxime and releasing 1M hydrochloric total carbonyl content of a lignin preparation can be determined by titration of the HCl acid.
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Alternatively, the carbonyl content may be determined by reduction with sodium or potassium borohydride（硼氢化钠）. After the reaction, excess of sodium or potassium borohydride is decomposed by addition of dilute sulfuric acid,and the volume of hydrogen thus liberated id measured carboxyl content is consumed borohydride .
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How to analyze the units co