Cleavage of aryl–ether bonds in lignin model compounds using a Co–Zn-beta catalyst

Dou, Xiaomeng; Li, Wenzhi; Zhu, Chaofeng; Jiang, Xiao; Chang, Hou‐min; Jameel, Hasan

doi:10.1039/d0ra08121c

Cited by 25 publications

(27 citation statements)

References 52 publications

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“…Based on these results and previously described works, 31,32 we propose a reaction pathway for guaiacylglycerol-b-guaiacyl ether hydrogenolysis to produce guaiacol and isoeugenol, as shown in Scheme 2. Firstly, a dehydration reaction occurs, which is promoted by the acidity of the medium to obtain compound A.…”

Section: Resultssupporting

confidence: 61%

Cobalt catalysts (Co–N–C) for C–O bond cleavage in lignin-derived aryl ethers and lignin

et al. 2023

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Section: Resultssupporting

confidence: 61%

Cobalt catalysts (Co–N–C) for C–O bond cleavage in lignin-derived aryl ethers and lignin

et al. 2023

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“…The analysis of the reaction mixture did not show any change in substrate concentration suggesting the inactivity of CoTPyP in the oxidant-free medium. Recent reports suggested the significant role of Zn complexes in the degradation of lignin model compounds. − Thus, the synthesized ZnTPyP was utilized for the conversion of compound 7 in the presence of sunlight. No reaction was observed because of the insolubility of the ZnTPyP under similar reaction conditions.…”

Section: Resultsmentioning

confidence: 99%

Sunlight Assisted Photocatalytic Valorization of Lignin Using Recyclable Light Harvesters

Reddy

Kirar

Thakur

et al. 2023

ACS Sustainable Chem. Eng.

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The abundant aromatic supply lignin, which is generated from agri-biomass, can be used as a sustainable alternative for several platform chemicals and fuels. The strongly cross-linked and randomly polymerized structure of lignin makes it difficult to valorize. In the current work, we have developed a solar photocatalytic system based on porphyrin that can directly depolymerize lignin and lignin-model compounds. The porphyrin has been evaluated for photophysical characteristics such as singlet oxygen and fluorescence quantum yields. The developed catalyst has been initially utilized for the degradation of lignin model compounds and then directly on lignin. For assessment, the degraded lignin various characterization techniques such as UV−vis spectroscopy, heteronuclear single quantum coherence spectroscopy (HSQC), electron paramagnetic resonance (EPR), mass spectroscopy, and gel permeation chromatography (GPC) were used. Later, a plausible mechanism for the breakdown of lignin/lignin model compounds was inferred after the developed photocatalytic system was investigated under a variety of experimental conditions. The photocatalyst's recovery and recyclability were further evaluated. This solar-assisted photocatalytic valorization of lignin driven by the light harvesters is a smart and sustainable initiative to synergize agri-waste removal and platform chemical generation.

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“…27,33,49 The hydrogenated product 14 of 11 is not much stable at high temperature, which should promote the formation of 6. 33 The appearance of 6 along with 14 as one of the major products con rms this hypothesis (Figures S3 and 4).…”

Section: Elucidation Of Reaction Pathwaysmentioning

confidence: 99%

“…24 In the next step, 21 underwent hydrogenolysis and hydrogenation reactions due to presence of highly polar solvent (water) and high pressure of hydrogen (Path IA) and produced compounds 1 and 11. 27,33,49 The hydrogenated product 14 of 11 is not much stable at high temperature, which should promote the formation of 6. 33 The appearance of 6 along with 14 as one of the major products con rms this hypothesis (Figures S3 and 4).…”

Section: Elucidation Of Reaction Pathwaysmentioning

confidence: 99%

Elucidating the Reaction Pathways of Veratrylglycero-β-guaiacyl Ether Degradation Over Metal-Free Solid Acid Catalysts with Hydrogen

Ruan

Kumar

et al. 2022

Preprint

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Efficient conversion of lignin to high-yield aromatic compounds for the potential production of fuels and chemicals is vital to the economics of the modern biorefinery industry. Herein, we report a novel catalytic process involving the cleavage of β-O-4 bonds, which are the major interunit linkages in native lignin. This work is distinct in that a detailed mechanistic analysis of the reaction pathways of veratrylglycero-β-guaiacyl ether (VGE) catalyzed by transition-metal-free solid acid zeolite under aqueous conditions at high hydrogen pressure has been performed. VGE degradation produced high yields of monomers (~ 87%), including guaiacol (48.2%), 1-(3,4-dimethoxyphenyl)ethanol (10.3%), 1-(3,4-dimethoxyphenyl)-2-propanol (6.1%), 3,4-dimethoxyphenylpropanol (4.7%), 3,4-dimethoxycinnamyl alcohol (4.1%), and 1,2-dimethoxy-4-propylbenzene (2%), which were identified and confirmed by both the in-situ solid-state magic angle spinning (MAS) 13C NMR under real-time conditions and two-dimensional gas chromatography analysis. The variety of products reveal the crucial roles of hydrogen, water, and acid sites for heterolytic cleavage of the β-O-4 bond in VGE. Decarbonylation, hydrogenolysis, hydrogenation, and dehydration reaction pathways are proposed and further validated using first-principles calculations.

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Cleavage of aryl–ether bonds in lignin model compounds using a Co–Zn-beta catalyst

Abstract: The catalytic hydrogenolysis of lignin model compounds containing aryl–ether linkages by Co–Zn-beta catalyst is investigated to understand the role of “Lewis acid-metal” catalysts in lignin depolymerization.

Cited by 25 publications

References 52 publications

Cobalt catalysts (Co–N–C) for C–O bond cleavage in lignin-derived aryl ethers and lignin

Cobalt catalysts (Co–N–C) for C–O bond cleavage in lignin-derived aryl ethers and lignin

Sunlight Assisted Photocatalytic Valorization of Lignin Using Recyclable Light Harvesters

Elucidating the Reaction Pathways of Veratrylglycero-β-guaiacyl Ether Degradation Over Metal-Free Solid Acid Catalysts with Hydrogen

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