Cleavage of lignin C–O bonds over a heterogeneous rhenium catalyst through hydrogen transfer reactions
作者:Bo Zhang、Zaojuan Qi、Xinxin Li、Jianwei Ji、Leilei Zhang、Hua Wang、Xiaoyan Liu、Changzhi Li
DOI:10.1039/c9gc01710k
日期:——
an important role in the cleavage of the C–O bonds. Notably, an ReOx/AC-catalyzed C–Obondcleavage pathway beyond a typical deoxydehydration mechanism was disclosed. More importantly, 2D-HSQC-NMR and GPC characterizations showed that ReOx/AC exhibited high activity not only in β-O-4 cleavage, but also in the deconstruction of more resistant β-5 and β–β linkages in lignin without destroying the aromatic
氢解是用于木质素解聚以生产芳香族化学品的最流行策略之一。当前,该策略主要在高氢气压力下进行,这会带来安全风险,并且不可持续且不经济。在本文中,我们报道了负载在活性炭上的异质氧化oxide(ReO x / AC)在异丙醇中木质素C–O键的选择性裂解中表现出出色的活性。在没有H 2的温和条件下,从各种木质素模型化合物中获得高产率的单酚(高达99.0%),从木质素原料中获得高产率的芳烃液体油(> 50%)。X射线吸收精细结构,X射线光电子能谱和H 2表征催化剂程序升温还原表明,ReO x / AC的活性可能归因于Re IV-VI的存在。活性炭和氧化oxide的表面氧基团之间的相互作用也可能在C–O键的断裂中起重要作用。值得注意的是,ReO x / AC催化的C–O键裂解途径超出了典型的脱氧脱水机理。更重要的是,2D-HSQC-NMR和GPC表征表明ReO x/ AC不仅在β-O-4裂解中表现出高
Selective Cleavage of C−O Bonds in Lignin Catalyzed by Rhenium(VII) Oxide (Re<sub>2</sub>O<sub>7</sub>)
作者:Zaojuan Qi、Bo Zhang、Jianwei Ji、Xinxin Li、Tao Dai、Haiwei Guo、Aiqin Wang、Lican Lu、Changzhi Li
DOI:10.1002/cplu.201700547
日期:2018.6
The selective cleavage of C-O bonds in typical model lignin β-O-4 compounds and deconstruction of a realistic lignin feedstock catalyzed by Re2 O7 is described. High yields of C-O cleavage products (up to 97.8 %) from model compounds and oils (76.3 %) from organosolv pinewood lignin were obtained under mild conditions. Evidence for the pathway of this catalytic process is also provided.
Mild and Robust Redox-Neutral Pd/C-Catalyzed Lignol β-O-4′ Bond Cleavage Through a Low-Energy-Barrier Pathway
作者:Maxim V. Galkin、Christian Dahlstrand、Joseph S. M. Samec
DOI:10.1002/cssc.201500117
日期:2015.7.8
A Pd/Ccatalyzedredox neutral CO bondcleavage of 2‐aryloxy‐1‐arylethanols has been developed. The reactions are carried out at 80 °C, in air, using a green solvent system to yield the aryl ketones in near quantitative yields. Addition of catalytic amounts of a hydrogen source to the reaction mixture activates the catalyst to proceed through a low energy barrier pathway. Initial studies support a
A photocatalytic strategy is developed for oxidativecleavage of C−Cbond in lignin models and natural lignin at room temperature. This strategy exhibits several advantages, such as aerobic environment, abundant and inexpensive chloride salts, facile generation of chlorine radical in the presence of organocatalyst, thus representing a significant advancement in the valorization of lignin into highly