Synthesis of Functional Lignophenol Derivatives from Native Lignin bySelective Phenol Grafting

设计了一种原始反应体系（相分离反应体系），用于将天然木质素转化为高酚性功能聚合物（木质素酚衍生物）。该体系由苯酚衍生物和浓酸组成，在室温下不能混溶。包括相分离系统在内的木质素功能化过程的关键是木质素和碳水化合物在不同的相中被单独修饰，木质素在有机相中存在，而碳水化合物在水相中存在。通过该工艺，木质素在侧链的calpha位置（反应性最强的位点）被选择性修饰，得到了高酚性、浅色的二苯甲烷型材料，这些材料仍然保留了生物合成过程中脱氢聚合形成的原始单元间键。碳水化合物被膨胀，随后在酸溶液中部分水解和溶解，导致细胞壁中互穿的聚合物网络结构被完美分解。因此，木质素的功能化和木质素与碳水化合物的分离在室温下迅速实现，与木材种类无关。木质素酚衍生物的分子量可以通过温和的碱性处理来控制。这是由于β -芳基醚键的选择性切割与苯酚衍生物的参与引入到calpha位置。与传统木质素制剂相比，木质素酚衍生物对蛋白质具有更高的亲和力。木质素酚-蛋白质复合物在所用蛋白质的等电点形成最有效。木质素酚衍生物与蛋白质之间一旦形成络合物，在任何ph值下都非常稳定。固定化在木质素酚衍生物上的酶具有很高的活性。

An original reaction system (the phase separative reaction system) has been designed for converting native lignins to highly phenolic, functional polymers (lignophenol derivatives). This system is composed of a phenol derivative and concentrated acid which are not miscible at room temperature. The key point of the lignin functionalization process including the phase separative system is that lignin and carbohydrates, which are totally different in structures and reactivities, are modified individually in the different phases : lignin is present in the organic phase and carbohydrates in the aqueous phase. Through the process, lignin was modified selectively at Calpha-positions of side chains, the most reactive sites, to give highly phenolic, light colored diphenylmethane type materials which still retained original interunit linkages formed by the dehydrogenative polymerization during the biosyntheses. The carbohydrates were swollen, followed by partial hydrolysis and dissolution in the acid solution, resulting in the perfect decomposition of interpenetrating polymer network structures in the cell wall. Therefore, the functionalization of lignin and the separation of resulting lignin from carbohydrates were quickly achieved at room temperature, independent of wood species. The molecular weights of lignophenol derivatives can be controlled by mild alkaline treatments. This is due to the selective cleavate of beta-aryl ether linkages with the participation of phenol derivatives introduced into Calpha-positions. Lignophenol derivatives had much higher affinities for proteins, compared with conventional lignin preparations. The lignophenol-protein complex was formed most effectively at the isoelectric point of used protein. Once the complex was formed between lignophenol derivatives and proteins, it was very stable at any pH.The enzymes immobilized on lignophenol derivatives had high activities.