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Table 4 Assignment of 13 C- 1 H cross-signals in the HSQC spectra of lignin

From: Differences in the adsorption of enzymes onto lignins from diverse types of lignocellulosic biomass and the underlying mechanism

Labels δCH(ppm) Assignments
Cβ 53.7/3.12 Cβ-Hβ in β-β (resinol) substructures (C)
Dβ 56.1/3.09 Cβ-Hβ in β-1 (spirodienone) substructures (D)
-OCH3 57.3/3.77 C-H in methoxyls
60.0/3.38 to 3.71 Cγ-Hγ in β-O-4 substructures (A)
A’γ 63.8/3.83 to 4.30 Cγ-Hγ in γ-acylated β-O-4′ substructures (A’ and A”)
71.7/3.81 and 4.17 Cγ-Hγ in β-β (resinol) substructures (C)
Aα/A’α 72.3/4.86 Cα-Hα in β-O-4 substructures (A, A’, and A”)
82.1/5.12 Cα-Hα in β-1 (spirodienone) substructures (D)
A’β 83.6/4.32 Cβ-Hβ in γ-acylated β-O-4 substructures (A’ and A”)
85.4/4.64 Cα-Hα in β-β (resinol) substructures (C)
85.4/4.80 -Hα in β-1 (spirodienone) substructures (D)
Aβ 86.5/4.10 Cβ-Hβ in γ-OH β-O-4 substructures (A)
87.7/5.45 Cα-Hα in β-5 (phenylcoumaran) substructures (B)
S2,6 103.8/6.68 C2-H2 and C6-H6 in etherified syringyl units
S2,6 (Cα = O) 106.7/7.36 and 7.21 C2-H2 and C6-H6 in oxidized (Cα = O) syringyl units
G2 111.5/6.99 C2-H2 in guaiacyl units
D2’ 111.6/6.23 C2’- H2’ in β-1 (spirodienone) substructures (D)
A”β’ 114.3/6.24 Cβ’-Hβ’ in p-coumaroylated substructures (A”)
G5 115.2/6.71 and 6.94 C5-H5 in guaiacyl units
A”3’,5’ 116.2/6.77 C3’- H3’ and C5’- H5’ in p-coumaroylated substructures (A”)
D6’ 118.3/6.19 C6’- H6’ in β-1 (spirodienone) substructures (D)
G6 119.5/6.83 C6-H6 in guaiacyl units
H2,6 128.2/7.17 C2-H2 and C6-H6 in p-hydroxyphenyl units
A”2’,6’ 130.5/7.4 C2’- H2’ and C6’- H6’ in p-coumaroylated substructures (A”)
A”α 145.1/7.39 -Hα in p-coumaroylated substructures (A”)