Thio-assisted reductive electrolytic cleavage of lignin β-O-4 models and authentic lignin

Avoiding the use of expensive catalysts and harsh conditions such as elevated temperatures and high pressures is a critical goal in lignin depolymerization and valorization. In this study, we present a thio-assisted electrocatalytic reductive approach using inexpensive reticulated vitreous carbon (R...

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Veröffentlicht in:Green chemistry : an international journal and green chemistry resource : GC 2021-01, Vol.23 (1), p.412-421
Hauptverfasser: Fang, Zhen, Flynn, Michael G, Jackson, James E, Hegg, Eric L
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Sprache:eng
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Zusammenfassung:Avoiding the use of expensive catalysts and harsh conditions such as elevated temperatures and high pressures is a critical goal in lignin depolymerization and valorization. In this study, we present a thio-assisted electrocatalytic reductive approach using inexpensive reticulated vitreous carbon (RVC) as the working cathode to cleave the β-O-4-type linkages in keto aryl ethers. In the presence of a pre-electrolyzed disulfide (2,2′-dithiodiethanol) and a radical inhibitor (BHT) at room temperature at a current density of 2.5 mA cm −2 , cathodic reduction of nonphenolic β-O-4 dimers afforded over 90% of the corresponding monomeric C-O cleavage products in only 1.5 h. Extended to DDQ-oxidized poplar lignin, this combination of electric current and disulfide, applied over 6 h, released 36 wt% of ethyl acetate soluble fragments and 26 wt% of aqueous soluble fragments, leaving only 38 wt% of insoluble residue. These findings represent a significant improvement over the current alone values (24 wt% ethyl acetate soluble; 22 wt% aqueous soluble; 54 wt% insoluble residue) and represent an important next step in our efforts to develop a mild electrochemical method for reductive lignin deconstruction. Disulfide-enhanced electroreductive cleavage of oxidized lignin β-O-4 dimers.
ISSN:1463-9262
1463-9270
DOI:10.1039/d0gc03597a