Laboratory of Sustainable and Catalytic Processing, Institute of Chemical Sciences and Engineering, École polytechnique fédérale de Lausanne, EPFL, 1015, Lausanne, Switzerland.
Angew Chem Int Ed Engl. 2018 Jan 26;57(5):1356-1360. doi: 10.1002/anie.201710838. Epub 2018 Jan 10.
Protection groups were introduced during biomass pretreatment to stabilize lignin's α,γ-diol group during its extraction and prevent its condensation. Acetaldehyde and propionaldehyde stabilized the α,γ-diol without any aromatic ring alkylation, which significantly increased final product selectivity. The subsequent hydrogenolysis catalyzed by Pd/C generated lignin monomers at near-theoretical yields based on Klason lignin (48 % from birch, 20 % from spruce, 70 % from high-syringyl transgenic poplar), and with high selectivity to a single 4-n-propanolsyringol product (80 %) in the case of the poplar. Unlike direct hydrogenation of native wood, hydrogenolysis of protected lignin with Ni/C also led to high selectivity to this single product (78 %), paving the way to high-selectivity lignin upgrading with base metal catalysts. The use of extracted lignin facilitated valorization of polysaccharides, leading to high yields of all three major biomass polymers to a single major product.
保护基团在生物质预处理过程中被引入，以稳定木质素α，γ-二醇基团在提取过程中的稳定性，防止其缩合。乙醛和丙醛稳定了α，γ-二醇而没有任何芳环烷基化，这显著提高了最终产物的选择性。随后由 Pd/C 催化的氢解反应以近乎理论产率生成木质素单体，基于 Klason 木质素（桦木 48%，云杉 20%，高愈创木酚型转基因杨木 70%），并且在杨木的情况下对单一 4-正丙基愈创木酚产物具有高选择性（80%）。与天然木材的直接加氢不同，Ni/C 保护的木质素氢解也导致对该单一产物的高选择性（78%），为使用基础金属催化剂进行高选择性木质素升级铺平了道路。提取的木质素的使用促进了多糖的增值，导致三种主要生物质聚合物中的所有单体都转化为单一主要产物，产率很高。
