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Fig. 7 | Biotechnology for Biofuels

Fig. 7

From: Characterization of lignin derived from water-only and dilute acid flowthrough pretreatment of poplar wood at elevated temperatures

Fig. 7

2-D 1H–13C HSQC correlation NMR spectra of aliphatic regions (left column) and aromatic regions (right column). a, b Ball-milled poplar wood lignin; c, d 240 °C, 0.05 % (w/w) H2SO4 for 10 min (pretreatment severity ~ 5.0); e, f 270 °C, water-only for 10 min (pretreatment severity ~ 6.0); a: β–O–4 aryl ether linkages; b: resinol substructures (β-–β′, α–O–γ′, and γ–O–α′ linkages); c: phenylcoumaran substructures (β–5′ and α–O–4′ linkages); d: spirodienone substructures (β–1′ and α–O–α′ linkages); G: guaiacyl units; G′: oxidized guaiacyl units with a Cα ketone; S: syringyl units; S′: oxidized syringyl units with a Cα ketone; e: p-hydroxybenzoate substructures; f: cinnamyl alcohol end groups; K: cinnamaldehyde end groups. Their structures can be found in Additional file 1: Figure S2

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