Cross-Coupling of Hydroxycinnamyl Aldehydes into Lignins
摘要:
[GRAPHICS]Pathways for hydroxycinnamyl aldehyde incorporation into lignins are revealed by examining transgenic plants deficient in cinnamyl alcohol dehydrogenase, the enzyme that converts hydroxycinnamyl aldehydes to the hydroxycinnamyl alcohol lignin monomers. In such plants the aldehydes incorporate into lignins via radical coupling reactions. As diagnostically revealed by long-range C-13-H-1 correlative NMR, sinapyl aldehyde (3,5-dimethoxy 4-hydroxy-cinnamaldehyde) 8-O-4-cross-couples with both gualacyl (3-methoxy-4-hydroxyphenyl-propanoid) and syringyl (3,5-dimethoxy-4-hydroxyphenyl-propanoid) units, whereas coniferyl aldehyde cross-couples only with syringyl units.
A method of selectively reacting lignin or a lignin-derived reactant to yield an aromatic product. The method includes the step of reacting lignin or a lignin-derived reactant with a molybdenum-containing catalyst, in a solvent, and optionally in the presence of an oxidant, for a time and a temperature wherein at least a portion of the lignin or lignin-derived reactant is selectively converted into an aromatic product, preferably coniferaldehyde and/or sinapaldehyde.
Rapid flow-through fractionation of biomass to preserve labile aryl ether bonds in native lignin
作者:Hao Zhou、Jia Yun Xu、Yingjuan Fu、Haiguang Zhang、Zaiwu Yuan、Menghua Qin、Zhaojiang Wang
DOI:10.1039/c9gc02315a
日期:——
dissolved lignin from the reactor in time and space, thereby preserving these labile aryl ether bonds in native lignin. The application of RFF of poplar wood with a short residence time of 2.6 min attained 75% delignification with an equivalent of the β-O-4 motif in native lignin. Structure-preserved lignins (β-O-4 retention, 75.0%–85.4%) were also harvested from wheat straw with good ligninyields (61.7%–78
The transformation of lignin into value-added chemicals represents one of the relevant approaches for sustainable development.
将木质素转化为增值化学品是可持续发展的相关方法之一。
Cleaving the βO4 Bonds of Lignin Model Compounds in an Acidic Ionic Liquid, 1-H-3-Methylimidazolium Chloride: An Optional Strategy for the Degradation of Lignin
作者:Songyan Jia、Blair J. Cox、Xinwen Guo、Z. Conrad Zhang、John G. Ekerdt
DOI:10.1002/cssc.201000112
日期:——
The hydrolysis of βO4bonds in two ligninmodelcompounds was studied in an acidicionicliquid, 1‐H‐3‐methylimidazolium chloride. The βO4bonds of both guaiacylglycerol‐β‐guaiacyl ether and veratrylglycerol‐β‐guaiacyl ether underwent catalytic hydrolysis to produce guaiacol as the primary product with more than 70 % yield at 150 °C. Up to 32 wt % substrate concentration could be treated in the
[GRAPHICS]Pathways for hydroxycinnamyl aldehyde incorporation into lignins are revealed by examining transgenic plants deficient in cinnamyl alcohol dehydrogenase, the enzyme that converts hydroxycinnamyl aldehydes to the hydroxycinnamyl alcohol lignin monomers. In such plants the aldehydes incorporate into lignins via radical coupling reactions. As diagnostically revealed by long-range C-13-H-1 correlative NMR, sinapyl aldehyde (3,5-dimethoxy 4-hydroxy-cinnamaldehyde) 8-O-4-cross-couples with both gualacyl (3-methoxy-4-hydroxyphenyl-propanoid) and syringyl (3,5-dimethoxy-4-hydroxyphenyl-propanoid) units, whereas coniferyl aldehyde cross-couples only with syringyl units.