Synthesis of Functional Lignophenol Derivatives from Native Lignin bySelective Phenol Grafting

设计了一个原始的反应系统（相分离反应系统），用于将天然木质素转化为高酚功能聚合物（木质酚衍生物）。该体系由在室温下不混溶的苯酚衍生物和浓酸组成。包括相分离系统在内的木质素功能化过程的关键是在不同的相中对结构和反应活性完全不同的木质素和碳水化合物进行单独修饰：木质素存在于有机相中而碳水化合物存在于水相中。通过该方法，木质素在侧链的α-位置（最具反应活性的位点）被选择性地改性，以得到高酚、浅色二苯甲烷型材料，其仍然保留在生物合成期间由分解聚合形成的原始单元间键。碳水化合物溶胀，然后部分水解并溶解在酸溶液中，导致细胞壁中互穿聚合物网络结构的完美分解。因此，木质素的功能化和所得木质素与碳水化合物的分离在室温下快速实现，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处理来控制。这是由于β-芳基醚键的选择性裂解与引入到α-位置的苯酚衍生物的参与。与传统的木质素制剂相比，木质素酚衍生物对蛋白质具有更高的亲和力。在所用蛋白质的等电点处，木质素酚-蛋白质复合物形成最有效。木质素酚衍生物与蛋白质形成复合物后，在任何pH下都很稳定，固定化酶具有较高的活性。

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.