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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

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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”)