- Chemodivergent hydrogenolysis of eucalyptus lignin with Ni@ZIF-8 catalyst
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Reductive catalytic fractionation (RCF) of lignocellulosic biomass, that is depolymerization of the native lignin component into well-defined monomeric phenols in the first step, offers an opportunity to utilize entire biomass components. Herein, we report that Ni@ZIF-8 can serve as a chemodivergent catalyst in RCF of eucalyptus sawdust, thus selectively producing phenolic compounds having either a propyl or propanol end-chain under different reaction conditions. In both cases, high yields of lignin monomers and a high degree of delignification were achieved, next to well-preserved carbohydrate pulp suitable for further processing. A mechanistic study using model compounds indicated that the dehydroxylation at the γ-position of the β-O-4 structure may be involved in the selectivity-controlling step.
- Liu, Xue,Li, Helong,Xiao, Ling-Ping,Sun, Run-Cang,Song, Guoyong
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supporting information
p. 1498 - 1504
(2019/03/26)
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- Cobalt-catalyzed Aerobic Oxidation of Eugenol to Vanillin and Vanillic Acid
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A novel, simple, one-step method of synthesizing vanillin and vanillic acid from eugenol has been developed. The method uses ligand- and additive-free Co(OAc)2·4H2O as catalyst and molecular oxygen as oxidant to achieve catalytic process without isomerizing eugenol. Extensive screening efforts were used to optimize eugenol to obtain vanillin and vanillic acid. Under optimal conditions, the reaction provided vanillin and vanillic acid with 68.5% and 15.2% yields, respectively. Apart from the desired products, coniferyl alcohol 9-methyl ether and 4-hydroxy-3-methoxycinnamaldehyde as two intermediates were also detected in the reaction process. Level changes of all compounds over time were presented in the reaction. The reaction pathway from eugenol to vanillic acid was validated by conducting several control experiments. Furthermore, a possible reaction mechanism dominated by a circular redox reaction from Co(III) and Co(II) species was proposed. This method offers a potentially practical alternative for manufacturing vanillin and vanillic acid efficiently.
- Mao, Haifang,Wang, Lizhi,Zhao, Feifei,Wu, Jianxin,Huo, Haohua,Yu, Jun
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p. 261 - 266
(2016/04/19)
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- Oxidative Studies on trans-(3-Phenyl-2-propenyl)phenols and 2-Methoxy-4-(2-propenyl)phenol and 2-Methoxy-4-(1-propenyl)phenol
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Oxidative reaction on trans-2-(3-phenyl-2-propenyl)phenols (1-4) and para-alkenylphenols have been studied.The products formed include benzofurane (5-8) and neolignane (16-18).
- Iyer, Meera R.,Baskaran, S.,Trivedi, Girish K.
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p. 341 - 344
(2007/10/02)
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- Synthesis and Reactivity of Vinyl Quinone Methides
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Vinyl quinone methides 4a and 4b were obtained in high yields by Ag2O oxidation of eugenol (3a) and of 2,6-dimethoxy-4-(2-propenyl)phenol (3b).Vinyl quinone methides (VQMs) reacted with alcohols, with phenols, and with acetic acid giving compounds 5 and 6.As the former rearranged to the latter in the reaction medium, the addition of the reported substrates to VQMs turned out to be wholly regioselective toward the formation of coniferyl and sinapyl derivatives 6.In contrast, addition of carbon nucleophiles (acetylacetone and EtNO2) to VQMs gave both compounds 7 and 8.By reaction of the acetates 6a and 6b (CR=CH3CO) with LiAlH4 it was possible to perform a novel synthesis of coniferyl and sinapyl alcohols (1a and 1b).Treatment of the same acetates with an aqueous solution of NaHCO3 reproduced VQMs 4, which by subsequent reduction with NaBH4, gave propenylphenols 2 and allylphenols 3.Formation of the latter compounds from coniferyl and sinapyl acetates via VQM is here proposed as a possible biosynthetic pathway.
- Zanarotti, Antonio
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p. 941 - 945
(2007/10/02)
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- Obtention et isomerisation du diphenyl-1,4 diformyl-2,3 butadiene (Z,Z)
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We report the synthesis of (Z,Z) 1,4-diphenyl-2,3-diformylbutadiene, a useful synthon: the dialdehyde 5 is prepared from hydrocarbon 1, via the new compounds 2, 3 and the diol 4a as intermediates.Hydrocarbon 1 gives, with selenium dioxide, the known selen
- Wehbe, Mohamed,Peyrot, Martial,Lepage, Lucette,Lepage, Yves
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p. 321 - 322
(2007/10/02)
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