Highly selective reductive cleavage of aromatic carbon–oxygen bonds catalyzed by a cobalt compound

Ren, Yunlai; Tian, Miao; Tian, Xuan; Wang, Qian; Shang, Huantao; Wang, Jianji; Zhang, Z. Conrad

doi:10.1016/j.catcom.2014.03.036

Cited by 31 publications

(12 citation statements)

References 22 publications

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“…Inspired by their work, we decided to study cobalt catalysts for catalytic biomass fractionation. So far, examples of cobalt catalysts in lignin valorization and related reactions are scarce . Co II acetylacetonate was reported to cleave aromatic C−O bonds by using LiAlH 4 as a reductant .…”

Section: Figurementioning

confidence: 89%

“…So far, examples of cobalt catalysts in lignin valorization and related reactions are scarce . Co II acetylacetonate was reported to cleave aromatic C−O bonds by using LiAlH 4 as a reductant . Recently, heterogeneous cobalt catalysts have been studied in hydrogenation of lignin‐derived phenols to cyclohexanols and hydrodeoxygenation of vanillin .…”

Section: Figurementioning

confidence: 99%

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Lignin Valorization by Cobalt‐Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds

et al. 2018

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Herein, a catalytic reductive fractionation of lignocellulose is presented using a heterogeneous cobalt catalyst and formic acid or formate as a hydrogen donor. The catalytic reductive fractionation of untreated birch wood yields monophenolic compounds in up to 34 wt % yield of total lignin, which corresponds to 76 % of the theoretical maximum yield. Model compound studies revealed that the main role of the cobalt catalyst is to stabilize the reactive intermediates formed during the organosolv pulping by transfer hydrogenation and hydrogenolysis reactions. Additionally, the cobalt catalyst is responsible for depolymerization reactions of lignin fragments through transfer hydrogenolysis reactions, which target the β‐O‐4′ bond. The catalyst could be recycled three times with only negligible decrease in efficiency, showing the robustness of the system.

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Section: Figurementioning

confidence: 89%

Section: Figurementioning

confidence: 99%

Lignin Valorization by Cobalt‐Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds

et al. 2018

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“…In these cases, a strong base was needed to obtain high selectivity toward the aromatics; otherwise, benzene ring hydrogenation occurs, leading to a mixture of aromatics and saturated hydrocarbons . The replacement of H 2 with active hydrogen donors, such as silane, NaBH 4 , and LiAlH 4 , could decrease the reaction temperature, making the reductive cleavage of 4‐O‐5 able to be carried out at low temperatures and possibly prohibiting the benzene ring hydrogenation …”

Section: The Challengesmentioning

confidence: 99%

Catalytic Scissoring of Lignin into Aryl Monomers

Wang

2019

Advanced Materials

140

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Lignin is an aromatic polymer, which is the biggest and most sustainable reservoir for aromatics. The selective conversion of lignin polymers into aryl monomers is a promising route to provide aromatics, but it is also a challenging task. Compared to cellulose, lignin remains the most poorly utilized biopolymer due to its complex structure. Although harsh conditions can degrade lignin, the aromatic rings are usually destroyed. This article comprehensively analyzes the challenges facing the scissoring of lignin into aryl monomers and summarizes the recent progress, focusing on the strategies and the catalysts to address the problems. Finally, emphasis is given to the outlook and future directions of this research.

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“…In the field of heterogeneous catalysis, third-row metal catalysts based on Ni, 5f,6 Co, 7 and Fe 8 were proved to be active for the hydrogenolysis of aromatic C-O bonds, providing high selectivities towards the production of aromatics and phenols. However, these catalysts typically possess limited activities and stabilities under the reaction conditions required for the transformation.…”

mentioning

confidence: 99%

Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)

Rengshausen

Etscheidt

Großkurth

et al. 2019

Synlett

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Catalytic hydrogenolysis of diaryl ethers is achieved by using ruthenium nanoparticles immobilized on an acidic supported ionic liquid phase (Ru@SILP-SO3H) as a multifunctional catalyst. The catalyst components are assembled through a molecular approach ensuring synergistic action of the metal and acid functions. The resulting catalyst is highly active for the hydrogenolysis of various diaryl ethers. For symmetric substrates such as diphenyl ether, hydrogenolysis is followed by full hydrodeoxygenation producing the corresponding cycloalkanes as the main products. For unsymmetric substrates, the cleavage of the C–O bond is regioselective and occurs adjacent to the unsubstituted phenyl ring. As hydrogenation of benzene is faster than hydrodeoxygenation over the Ru@SILP-SO3H catalyst, controlled mixtures of cyclohexane and substituted phenols are accessible with good selectivity. Application of Ru@SILP-SO3H catalyst in continuous-flow hydrogenolysis of 2-methoxy-4-methylphenoxybenzene is demonstrated with use of commercial equipment.

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Highly selective reductive cleavage of aromatic carbon–oxygen bonds catalyzed by a cobalt compound

Cited by 31 publications

References 22 publications

Lignin Valorization by Cobalt‐Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds

Lignin Valorization by Cobalt‐Catalyzed Fractionation of Lignocellulose to Yield Monophenolic Compounds

Catalytic Scissoring of Lignin into Aryl Monomers

Catalytic Hydrogenolysis of Substituted Diaryl Ethers by Using Ruthenium Nanoparticles on an Acidic Supported Ionic Liquid Phase (Ru@SILP-SO3H)

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