木素的氧化性氨化反应(英文)

Oxidative Ammonolysis of Lignin

在一定压力和温度条件下,木素大分子和氨发生反应,生成一些氮修饰木素.为了解反应过程中木素分子结构的变化,用13 C和1H - 13 C 2D -NMRHMQC技术检测了反应前后的分子谱图,结果显示反应过程中木素分子的碎裂化现象十分明显,很可能在氧化性氨化反应过程中,木素大分子表面基团发生了氧化性修饰,如一些侧链 -CH3 被氧化形成 -CHO和 -COOH等,然后这些基团与氨结合等;此外,芳香环结构可能通过粘康酸单体断裂形成一些酰胺类产物。

Two stages were found in the process for 165 min of oxidative ammonolysis of kraft wheat lignin with the first from 0-45 min and the second from 45-165 min. The reaction was complying with pseudo_first order equation:ln[( N ∞- N t)/N ∞]=-k t . Results from dynamics experiment showed that about 2.3% nitrogen was integrated into lignin macromolecule under 100℃, but nitrogen compounded amounted to 3.7% under 130℃. It is indicated from 1 H- 13 C 2D-NMR HMQC spectroscopy that fragmentation of lignin molecule was drastic during oxidative ammonolysis, probably oxidative modification of bases on the surface of lignin molecule took place, such as formation of -CHO and -COOH from -CH 3 or -CH 2, then nitrogen was combined into it. However,there was no obvious change found in the inner highly_condensed lignin structures.