Study on the cleavage of alkyl-O-aryl bonds by in situ generated hydroxyl radicals on an ORR cathode

Wang, Lei; Chen, Yongmei; Liu, Shuangyan; Jiang, Haomin; Wang, Linan; Sun, Yanzhi; Wan, Pingyu

doi:10.1039/c7ra11236j

Cited by 26 publications

(18 citation statements)

References 35 publications

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“…Volmer et al (Table , entry 7) studied the lignin ECOD with reticulated vitreous carbon foam electrodes and using two different ILs, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][OTf]) and triethylammonium methanesulfonate (TMS). They demonstrated the participation of electrogenerated H 2 O 2 or hydroxyl radicals (from the oxidation of intentionally added H 2 O) as both auxiliary oxidant and radical scavenger (as also observed in other works − ), which inhibits the repolymerization of monomers under oxidative pathways. TMS and [emim][OTf] showed maximum lignin decomposition rates of 22–31 and 19–23 wt%, respectively.…”

Section: Demonstrated Electrochemical Routes For Conversion Of Interm...supporting

confidence: 70%

“…Several authors also studied the ECOD of lignin model molecules, ,, which can represent some specific linkages present in real lignin but do not show some of the most technologically challenging limitations of this macro-molecule such as low solubility in pH below 9, low diffusion coefficients (which limit the direct electrolysis) and the general recalcitrance.…”

Section: Demonstrated Electrochemical Routes For Conversion Of Interm...mentioning

confidence: 99%

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Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

et al. 2021

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The drive to reduce consumption of fossil resources, coupled with expanding capacity for renewable electricity, invites the exploration of new routes to utilize this energy for the sustainable production of fuels, chemicals, and materials. Biomass represents a possible source of platform precursors for such commodities due to its inherent ability to fix CO 2 in the form of multi-carbon organic molecules. Electrochemical methods for the valorization of biomass are thus intriguing, but there is a need to objectively evaluate this field and define the opportunity space by identifying pathways suited to electrochemistry. In this contribution we offer a comprehensive, critical review of recent advances in lowtemperature (liquid phase), electrochemical reduction and oxidation of biomass-derived intermediates (polyols, furans, carboxylic acids, amino acids, and lignin), with emphasis on identifying the state-of-the-art for each documented reaction. Progress in computational modeling is also reviewed. We further suggest a number of possible reactions that have not yet been explored but which are expected to proceed based on established routes to transform specific functional groups. We conclude with a critical discussion of technological challenges for scale-up, fundamental research needs, process intensification opportunities (e.g., by pairing compatible oxidations and reductions), and new benchmarking standards that will be necessary to accelerate progress toward application in this still-nascent field.

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Section: Demonstrated Electrochemical Routes For Conversion Of Interm...supporting

confidence: 70%

Section: Demonstrated Electrochemical Routes For Conversion Of Interm...mentioning

confidence: 99%

Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

et al. 2021

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“…Based on several well-designed experiments, it was confirmed that the main ROS was *OH. The degradation rate and product yield displayed a good positive linear relationship with the concentration of the electro-generated *OH on the ORR cathode [67]. This result indirectly proves that, compared with a single electrode, the synergistic effect of anode and cathode greatly increase the degradation efficiency of lignin.…”

Section: Degradation Of Lignin and Lignin Model Compounds By Ros Genementioning

confidence: 58%

Electrochemical Degradation of Lignin by ROS

Jiang

Xue

Wang

et al. 2020

Sustainable Chemistry

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Lignin is a unique renewable aromatic resource in nature. In the past decades, researchers have attempted to breakdown the linkage bonds in lignin to provide aromatic platform chemicals that used to come from the petrochemical industry. In recent years, electrochemical lignin degradation under mild conditions has drawn much attention from the scientific community owing to its potential to scale up and its environmental friendliness. Sustainable electrochemical degradation of lignin consumes less energy and usually requires mild conditions, but low degradation efficiency and insufficient product selectivity are still significant challenges. The method for lignin degradation by reactive oxygen species (ROS) generated through the water oxidation reaction (WOR) at the anode and oxygen reduction reaction (ORR) at the cathode are more attractive for sustainable electrochemical degradation. The present contribution aims to review advancements in electrochemical degradation of lignin in aqueous or non-aqueous supporting electrolytes, focusing on the regulation of ROS in situ generated on the electrode.

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“…The above phenomena indicate that the DR of PBP strongly depends on the amount of hydroxyl radicals (•OH) that are produced through catalyzed decomposition of H2O2. The decomposition of H2O2 follows the first-order kinetic reaction with reaction rate constants of 0.0121 min -1 at 20 °C, 0.0396 min -1 at 40 °C, and 0.0965 min -1 at 60 °C, respectively (Lei et al 2017). The amount of •OH increased when the initial concentration of H2O2, the dosage of catalyst, and the reaction temperature were increased.…”

Section: Optimization Of Degradation Conditionsmentioning

confidence: 99%

“…Lignin or lignin model compounds could be depolymerized by H2O2 oxidative degradation, in which the generated reactive oxygen species (ROS) act as oxidizing reagent (Kang et al 2019). Certain products are generated by selective cleavage of linkage bonds (Lei et al 2017;Jiang et al 2019). However, the product selectivity is reduced if a liquor having strong acidity (such as H2SO4) is used as the co-catalyst because over-oxidation of the products can occur, making product separation difficult.…”

Section: Introductionmentioning

confidence: 99%

A two-phase reaction system for selective oxidative degradation of lignin model compounds

Chen

Xue

Jiang

et al. 2020

BioRes

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Lignin depolymerization through an oxidation method could provide value-added products, but it is challenging in terms of recovering catalysts or separating products in time to avoid over-oxidation. In this study, a process of selectively oxidative degradation of lignin model compounds was operated in a two-phase reaction system. Lignin model compounds of 4-benzyloxyphenol (PBP) or guaiacylglycerol-β-guaiacyl ether (GGE) in a bottom phase of 1-butyl-3-methylimidazole chloride ([BMIM]Cl) ionic liquid were selectively oxidized by H2O2 in the presence of a solid acid (SO42-/Fe2O3-ZrO2), and the degradation products immediately diffused into the upper organic solvent phase (butyl acetate). In this kind of reaction system, the yield of the products was improved due to the prolonged life of ∙OH in ionic liquid, and the product selectivity was maintained due to the timely product separation, and the ionic liquid and the catalyst were easily recycled.

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Study on the cleavage of alkyl-O-aryl bonds by in situ generated hydroxyl radicals on an ORR cathode

Abstract: ˙OH selectively attacks the active sites opposite to phenolic hydroxyl groups and leads to bond-cleavage of ether bonds.

Cited by 26 publications

References 35 publications

Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

Electrochemical Routes for the Valorization of Biomass-Derived Feedstocks: From Chemistry to Application

Electrochemical Degradation of Lignin by ROS

A two-phase reaction system for selective oxidative degradation of lignin model compounds

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