Enhancement of Lignin Biopolymer Isolation from Hybrid Poplar by Organosolv Pretreatments

Figure 6

Main substructures present in the alcohol lignin of hybrid poplar: (A) -O-4′ alkyl-aryl ethers; (A′) Cα-substituted -O-4′ structures (R=CH₃, CH₂CH₃, CH₂CH₂CH₃, CH₂CH₂CH₂CH₃); (B) resinol; (C) phenylcoumaran; (F) cinnamyl alcohol end-group; (I) stilbenes; (PB) p-hydroxybenzoate; (G) guaiacyl units; (S) syringyl units; (S′) oxidized syringyl units.