99634-01-2Relevant academic research and scientific papers
Cleavage∕cross-coupling strategy for converting β-O-4 linkage lignin model compounds into high valued benzyl amines via dual C–O bond cleavage
Jia, Le,Li, Chao-Jun,Zeng, Huiying
supporting information, (2021/10/29)
Lignin is the most recalcitrant of the three components of lignocellulosic biomass. The strength and stability of the linkages have long been a great challenge for the degradation and valorization of lignin biomass to obtain bio-fuels and commercial chemicals. Up to now, the selective cleavage of C–O linkages of lignin to afford chemicals contains only C, H and O atoms. Our group has developed a cleavage/cross-coupling strategy for converting 4-O-5 linkage lignin model compounds into high value-added compounds. Herein, we present a palladium-catalyzed cleavage/cross-coupling of the β-O-4 lignin model compounds with amines via dual C–O bond cleavage for the preparation of benzyl amine compounds and phenols.
Selective Cα Alcohol Oxidation of Lignin Substrates Featuring a β-O-4 Linkage by a Dinuclear Oxovanadium Catalyst via Two-Electron Redox Processes
Tsai, Yan-Ting,Chen, Chih-Yao,Hsieh, Yi-Ju,Tsai, Ming-Li
supporting information, p. 4637 - 4646 (2019/11/16)
Developing highly efficient catalyst systems to transform lignin biomass into value-added chemical feedstocks is imperative for utilizing lignin as renewable alternatives to fossil fuels. Recently, the pre-activated strategy involving the selective oxidat
Gold nanoparticles stabilized by graphene quantum dots as catalysts for C–C bond cleavage in β-O-4 lignin model compounds
Zhang, Fangwei,Zhang, Jiali,Guo, Shouwu
, p. 105 - 109 (2019/04/08)
In this work, we report oxidative cleavage of C–C bonds in β-O-4 lignin models that is catalyzed by gold nanoparticles stabilized by graphene quantum dots (AuNPs-GQDs). We demonstrate that GQDs can enhance the catalytic activity of AuNPs. The AuNPs-GQDs shows the highest catalytic activity when the mass ratio of AuNPs to GQDs is of 1:18. Moreover, AuNPs-GQDs exhibits higher activity in the cleavage of Cα–Cβ bond of the compounds when their Cβ is adjacent to an oxygen atom. The possible oxidation pathway is proposed.
Hydrogenolysis of β-O-4 lignin model dimers by a ruthenium-xantphos catalyst
Wu, Adam,Patrick, Brian O.,Chung, Enoch,James, Brian R.
, p. 11093 - 11106 (2012/10/30)
Hydrogenolysis reactions of so-called lignin model dimers using a Ru-xantphos catalyst are presented (xantphos = 4,5-bis(diphenylphosphino)-9,9- dimethylxanthene). For example, of some nine models studied, the alcohol, 2-(2-methoxyphenoxy)-1-phenylethanol (1), with 5 mol% Ru(H)2(CO) (PPh3)(xantphos) (18) in toluene-d8 at 135 °C for 20 h under N2, gives in ～95% yield the C-O cleavage hydrogenolysis products, acetophenone (14) and guaiacol (17), and a small amount (1H NMR spectroscopy. The in situ Ru(H)2(CO)(PPh 3)3/xantphos system gives similar findings, confirming a recent report (J. M. Nichols et al., J. Am. Chem. Soc., 2010, 132, 12554). The active catalyst is formulated 'for convenience' as 'Ru(CO)(xantphos)'. The hydrogenolysis mechanism proceeds by initial dehydrogenation to give the ketone 4, which then undergoes hydrogenolysis of the C-O bond to give 14 and 17. Hydrogenolysis of 4 to 14 and 17 also occurs using the Ru catalyst under 1 atm H2; in contrast, use of 3-hydroxy-2-(2-methoxyphenoxy)-1-phenyl-1- propanone (7), for example, where the CH2 of 4 has been changed to CHCH2OH, gives a low yield (≤15%) of hydrogenolysis products. Similarly, the diol substrate, 2-(2-methoxyphenoxy)-1-phenyl-1,3-propanediol (9), gives low yields of hydrogenolysis products. These low yields are due to formation of the catalytically inactive complexes Ru(CO)(xantphos)[C(O)C(OC 6H4OMe)C(Ph)O] (20) and/or Ru(CO)(xantphos)[C(O)CHC(Ph)O] (21), where the organic fragments result from dehydrogenation of CH 2OH moieties in 7 and 9. Trace amounts of Ru(CO)(xantphos)(OC 6H4O), a catecholate complex, are isolated from the reaction of 18 with 1. Improved syntheses of 18 and lignin models are also presented.
