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 H₂O, on the cleavage of inter‐ and intramolecular linkages of lignin in corncob residue were investigated. At 200 °C, miscible cosolvents (H₂O–GBL, H₂O–GVL, and H₂O–THF) exhibited much better efficiency for lignin dissolution than that of both immiscible cosolvents (H₂O–EAC and H₂O–2‐MeTHF) and pure solvents. The synergetic effect between H₂O 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 H₂O–GBL cosolvent, whereas the β−O−4, α−O−4, and β−5 linkages were cleaved in H₂O–EAC, H₂O–THF, and H₂O–2‐MeTHF cosolvents. At 300 °C, the breakage of the β−γ bond prior to β−O−4 in H₂O–GBL, H₂O–THF, H₂O–EAC, and H₂O–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 H₂O–GVL to form guaiacol (accounting for ≈75 % of the total identified monophenols).

中文翻译：

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几种溶剂对玉米芯残留物中木质素分子间和分子内连接的裂解作用

溶剂的性能包括γ-丁内酯（GBL），γ-戊内酯（GVL），四氢呋喃（THF），乙酸乙酯（EAC），2-甲基四氢呋喃（2-MeTHF）以及与H ₂ O对应的混合物研究了玉米芯残基中木质素的分子间和分子内连接的裂解。在200°C时，与两种不混溶助溶剂（H ₂ O–EAC和H ₂ O）相比，可混溶助溶剂（H ₂ O–GBL，H ₂ O–GVL和H ₂ O–THF）的木质素溶解效率要好得多。–2–MeTHF）和纯溶剂。H ₂之间的协同作用O和有机溶剂显着促进了无定形纤维素的C6-OH与木质素之间的分子间键的断裂。GBL和THF溶剂优先溶解具有H和G单元的木质素，而GVL，EAC和2-MeTHF溶剂对溶解具有S和G单元的木质素表现出高选择性。除溶解外，木质素中的分子内β-O-4键可在H ₂ O-GBL助溶剂中选择性裂解，而β-O-4，α-O-4和β-5键可在H中裂解₂ O-EAC，H ₂ O-THF和H ₂ O-2-MeTHF助溶剂。在300°C时，H ₂ O–GBL，H ₂ O–THF，H ₂ O–EAC和H _2中的β−O-4之前的β-γ键断裂O-2-MeTHF选择性地产生4-乙基苯酚和4-乙基愈创木酚（约占已鉴定的单酚总量的70％），而α-1键最好在H ₂ O-GVL中断裂而形成愈创木酚（占约75）占总鉴定出的单酚的百分比）。