1416781-15-1Relevant articles and documents
Visible-light-induced C-C bond cleavage of lignin model compounds with cyanobenziodoxolone
Zheng, Ming,Huang, Yan,Zhan, Le-Wu,Hou, Jing,Li, Bin-Dong
, (2020)
The catalytic degradation of lignin to value-added chemicals has received considerable attention over the past decade. Photocatalysis provides promising approaches to enable previously inaccessible transformations. However, examples of the visible-light promoted degradation of lignin are still limited. In this work, the visible-light-induced selective C-C bond cleavage of β-O-4 lignin model compounds has been disclosed via β-scission of in situ generated alkoxy radical intermediates. With cyanobenziodoxolone as the oxidant, a variety of substrates could be transformed into aldehydes in moderate to good yields. In addition, unexpected acetal esters which could conveniently furnish formaldehyde and phenols by alcoholysis were observed.
A multicentre synergistic polyoxometalate-based metal-organic framework for one-step selective oxidative cleavage of β-: O -4 lignin model compounds
Tian, Hong-Rui,Liu, Yi-Wei,Zhang, Zhong,Liu, Shu-Mei,Dang, Tian-Yi,Li, Xiao-Hui,Sun, Xiu-Wei,Lu, Ying,Liu, Shu-Xia
, p. 248 - 255 (2020/01/13)
A novel mixed-valence polyoxovanadate-based copper-organic framework, [CuI(bbi)]2{[CuI(bbi)]2VIV2VV8O26}·2H2O (NENU-MV-5, bbi = 1,1′-(1,4-butanediyl)bis(imidazole)), was facilely synthesized from routine reagents under mild hydrothermal conditions. Using NENU-MV-5 as a heterogeneous catalyst without any co-catalyst, one-step oxidative cleavage of β-O-4 lignin into phenols and aromatic acids with high catalytic activity and selectivity was realized under an oxygen atmosphere. No obvious decrease in activity was observed after five cycles, which indicates the excellent stability and sustainability of NENU-MV-5. The perfect catalytic performance of NENU-MV-5 can be attributed to the multi-site synergistic effect of the mixed-valence VV-O-VIV sites on polyoxovanadate for the oxidation of β-O-4 alcohol to β-O-4 ketone and the Cu(i) sites on the framework for the rapid cleavage of the Cα-Cβ bond of β-O-4 ketone. This system represented the first co-catalyst-free example for the one-step selective degradation of lignin catalyzed by a well-defined crystalline catalyst with definite composition and structure in a single solvent.
Visible light induced redox neutral fragmentation of 1,2-diol derivatives
Chen, Kang,Schwarz, Johanna,Karl, Tobias A.,Chatterjee, Anamitra,K?nig, Burkhard
, p. 13144 - 13147 (2019/11/11)
A homogeneous, redox-neutral photo fragmentation of diol derivatives was developed. Under photo/hydrogen atom transfer (HAT) dual catalysis, diol derivatives such as lignin model compounds and diol monoesters undergo selective β C(sp3)-O bond cleavage to afford ketones, phenols and acids effectively.
Photocatalytic Oxidation of Lignin Model Systems by Merging Visible-Light Photoredox and Palladium Catalysis
K?rk?s, Markus D.,Bosque, Irene,Matsuura, Bryan S.,Stephenson, Corey R. J.
supporting information, p. 5166 - 5169 (2016/10/14)
Lignin valorization has long been recognized as a sustainable solution for the renewable production of aromatic compounds. Two-step oxidation/reduction strategies, whereby the first oxidation step is required to "activate" lignin systems for controlled fragmentation reactions, have recently emerged as viable routes toward this goal. Herein we describe a catalytic protocol for oxidation of lignin model systems by combining photoredox and Pd catalysis. The developed dual catalytic protocol allowed the efficient oxidation of lignin model substrates at room temperature to afford the oxidized products in good to excellent yields.
SELECTIVE C-O BOND CLEAVAGE OF OXIDIZED LIGNIN AND LIGNIN-TYPE MATERIALS INTO SIMPLE AROMATIC COMPOUNDS
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Page/Page column 22-23; 24, (2015/10/05)
A method to cleave C-C and C-0 bonds in β-Ο-4 linkages in lignin or lignin sub-units is described. The method includes oxidizing at least a portion of secondary benzylic alcohol groups in β-Ο-4 linkages in the lignin or lignin sub-unit to corresponding ketones and then leaving C-0 or C-C bonds in the oxidized lignin or lignin sub-unit by reacting it with an organic carboxylic acid, a salt of an organic carboxylic acids, and/or an ester of an organic carboxylic acids. The method may utilize a metal or metal-containing reagent or proceed without the metal or metal-containing reagent.
SELECTIVE AEROBIC ALCOHOL OXIDATION METHOD FOR CONVERSION OF LIGNIN INTO SIMPLE AROMATIC COMPOUNDS
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Paragraph 0061; 0062; 0063; 0066; 0067, (2014/09/03)
Described is a method to oxidize lignin or lignin sub-units. The method includes oxidation of secondary benzylic alcohol in the lignin or lignin sub-unit to a corresponding ketone in the presence of unprotected primarily aliphatic alcohol in the lignin or lignin sub-unit. The optimal catalyst system consists of HNO3 in combination with another Br?nsted acid, in the absence of a metal-containing catalyst, thereby yielding a selectively oxidized lignin or lignin sub-unit. The method may be carried out in the presence or absence of additional reagents including TEMPO and TEMPO derivatives.
Mechanochemical degradation of lignin and wood by solvent-free grinding in a reactive medium
Kleine, Tillmann,Buendia, Julien,Bolm, Carsten
supporting information, p. 160 - 166 (2013/02/23)
A mechanochemical approach for the cleavage of β-O-4-linkages in lignin is reported. The method is transition metal- and solvent-free, requires only inexpensive reagents, and tolerates the presence of water and standard reagent impurities.
Chemoselective metal-free aerobic alcohol oxidation in lignin
Rahimi, Alireza,Azarpira, Ali,Kim, Hoon,Ralph, John,Stahl, Shannon S.
supporting information, p. 6415 - 6418 (2013/06/05)
An efficient organocatalytic method for chemoselective aerobic oxidation of secondary benzylic alcohols within lignin model compounds has been identified. Extension to selective oxidation in natural lignins has also been demonstrated. The optimal catalyst system consists of 4-acetamido-TEMPO (5 mol %; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) in combination with HNO3 and HCl (10 mol % each). Preliminary studies highlight the prospect of combining this method with a subsequent oxidation step to achieve C-C bond cleavage.
