Yang Xiaohui, Li Ning, Lin Xuliang, Pan Xuejun, Zhou Yonghong
Institute of Chemical Industry of Forestry Products, Chinese Academy of Forestry , Nanjing 210042, China.
Department of Biological Systems Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
J Agric Food Chem. 2016 Nov 9;64(44):8379-8387. doi: 10.1021/acs.jafc.6b03807. Epub 2016 Oct 27.
The present study demonstrates that the concentrated lithium bromide (LiBr) solution with acid as catalyst was able to selectively cleave the β-O-4 aryl ether bond and lead to lignin depolymerization under mild conditions (e.g., in 60% LiBr with 0.3 M HCl at 110 °C for 2 h). Four industrial lignins from different pulping and biorefining processes, including softwood kraft lignin (SKL), hardwood kraft lignin (HKL), softwood ethanol organosolv lignin (EOL), and acid corncob lignin (ACL), were treated in the LiBr solution. The molecular weight, functional group, and interunit linkages of the lignins were characterized using GPC, FTIR, and NMR. The results indicated that the β-O-4 aryl ether bonds of the lignins were selectively cleaved, and both LiBr and HCl played crucial roles in catalyzing the cleavage of the ether bonds.
本研究表明，以酸为催化剂的浓溴化锂（LiBr）溶液能够在温和条件下（例如，在60% LiBr与0.3 M HCl中于110 °C反应2小时）选择性地裂解β-O-4芳基醚键并导致木质素解聚。对来自不同制浆和生物精炼过程的四种工业木质素进行了LiBr溶液处理，包括软木硫酸盐木质素（SKL）、硬木硫酸盐木质素（HKL）、软木乙醇有机溶剂木质素（EOL）和酸性玉米芯木质素（ACL）。使用凝胶渗透色谱（GPC）、傅里叶变换红外光谱（FTIR）和核磁共振（NMR）对木质素的分子量、官能团和单元间连接进行了表征。结果表明，木质素的β-O-4芳基醚键被选择性裂解，LiBr和HCl在催化醚键裂解中均起关键作用。
