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Performances of Several Solvents on the Cleavage of Inter‐ and Intramolecular Linkages of Lignin in Corncob Residue
Author(s) -
Zhang Hui,
Liu Xudong,
Li Jianmei,
Jiang Zhicheng,
Hu Changwei
Publication year - 2018
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201800309
Subject(s) - chemistry , lignin , intramolecular force , dissolution , solvent , tetrahydrofuran , guaiacol , medicinal chemistry , bond cleavage , organic chemistry , catalysis
Abstract The performances of solvents, including γ‐butyrolactone (GBL), γ‐valerolactone (GVL), tetrahydrofuran (THF), ethyl acetate (EAC), 2‐methyltetrahydrofuran (2‐MeTHF), and the corresponding mixtures with H 2 O, on the cleavage of inter‐ and intramolecular linkages of lignin in corncob residue were investigated. At 200 °C, miscible cosolvents (H 2 O–GBL, H 2 O–GVL, and H 2 O–THF) exhibited much better efficiency for lignin dissolution than that of both immiscible cosolvents (H 2 O–EAC and H 2 O–2‐MeTHF) and pure solvents. The synergetic effect between H 2 O and organic solvent significantly promoted the breakage of intermolecular linkages between C6−O−H of amorphous cellulose and lignin. GBL and THF solvents preferentially dissolved lignin with H and G units, whereas GVL, EAC, and 2‐MeTHF solvents exhibited high selectivity for the dissolution of lignin with S and G units. In addition to dissolution, the intramolecular β−O−4 linkage in lignin could be selectively cleaved in H 2 O–GBL cosolvent, whereas the β−O−4, α−O−4, and β−5 linkages were cleaved in H 2 O–EAC, H 2 O–THF, and H 2 O–2‐MeTHF cosolvents. At 300 °C, the breakage of the β−γ bond prior to β−O−4 in H 2 O–GBL, H 2 O–THF, H 2 O–EAC, and H 2 O–2‐MeTHF produced 4‐ethylphenol and 4‐ethylguaiacol selectively (accounting for ≈70 % of the total identified monophenols), whereas the α−1 bond was preferably broken in H 2 O–GVL to form guaiacol (accounting for ≈75 % of the total identified monophenols).