Li Yanding, Shuai Li, Kim Hoon, Motagamwala Ali Hussain, Mobley Justin K, Yue Fengxia, Tobimatsu Yuki, Havkin-Frenkel Daphna, Chen Fang, Dixon Richard A, Luterbacher Jeremy S, Dumesic James A, Ralph John
U.S. Department of Energy Great Lakes Bioenergy Research Center, and Wisconsin Energy Institute, University of Wisconsin-Madison, Madison, WI 53726, USA.
Department of Biological Systems Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
Sci Adv. 2018 Sep 28;4(9):eaau2968. doi: 10.1126/sciadv.aau2968. eCollection 2018 Sep.
Lignin, a major component of lignocellulosic biomass, is crucial to plant growth and development but is a major impediment to efficient biomass utilization in various processes. Valorizing lignin is increasingly realized as being essential. However, rapid condensation of lignin during acidic extraction leads to the formation of recalcitrant condensed units that, along with similar units and structural heterogeneity in native lignin, drastically limits product yield and selectivity. Catechyl lignin (C-lignin), which is essentially a benzodioxane homopolymer without condensed units, might represent an ideal lignin for valorization, as it circumvents these issues. We discovered that C-lignin is highly acid-resistant. Hydrogenolysis of C-lignin resulted in the cleavage of all benzodioxane structures to produce catechyl-type monomers in near-quantitative yield with a selectivity of 90% to a single monomer.
木质素是木质纤维素生物质的主要成分，对植物生长发育至关重要，但在各种过程中却是生物质高效利用的主要障碍。将木质素转化为有价值的物质越来越被认为是必不可少的。然而，酸性提取过程中木质素的快速缩合会导致形成难降解的缩合单元，这些单元与天然木质素中的类似单元和结构异质性一起，极大地限制了产物的产率和选择性。儿茶酚型木质素（C-木质素）本质上是一种没有缩合单元的苯并二恶烷均聚物，可能是一种理想的可转化木质素，因为它避免了这些问题。我们发现C-木质素具有高度耐酸性。C-木质素的氢解导致所有苯并二恶烷结构断裂，以接近定量的产率生成儿茶酚型单体，对单一单体的选择性为90%。
