Table 3 Assignments of lignin main¹³C-¹H correlation signals in the heteronuclear single quantum correlation spectra of eucalypt wood and lignins

B_β

53.1/3.45

C_β - H_β in phenylcoumaran substructures (B)

C_β

53.3/3.05

C_β - H_β in β - βʹ resinol substructures (C)

MeO

55.6/3.72

C - H in methoxyls

A_γ

59.4 /3.38 and 3.70

C_γ - H_γ in β-O-4ʹ structures (A)

D_β

59.7/2.73

C_β - H_β in spirodienone substructures (D)

I_γ

61.3/4.08

C_γ - H_γ in cinnamyl alcohol end-groups (I)

B_γ

62.6/3.67

C_γ - H_γ in phenylcoumaran substructures (B)

A_α

71.8/4.85

C_α - H_α in β-O-4ʹ structures (A)

C_γ

71.0/ 3.81 and 4.18

C_γ - H_γ in β - βʹ resinol substructures (C)

D_β'

79.2/4.10

C_βʹ - H_βʹ in spirodienone substructures (D)

D_α

81.0/5.08

C_α - H_α in spirodienone substructures (D)

A_oxβ

83.0/5.20

C_β - H_β in α-oxidized β-O-4′ substructures ( A _ox )

A_β(G)

83.6/4.28

C_β - H_β in β-O-4ʹ structures (A) linked to a G-unit

D_α'

83.7/4.68

C_αʹ - H_αʹ in spirodienone substructures (D)

C_α

84.7/4.64

C_α - H_α in β - β′ resinol substructures (C)

A_β(S)

85.7/4.10

C_β - H_β in β-O-4ʹ structures (A) linked to a S-unit

B_α

86.4/5.43

C_α - H_α in phenylcoumaran substructures (B)

S_2,6

103.9/6.69

C₂ - H₂ and C₆ - H₆ in syringyl units (S)

Sʹ_2,6

106.1/7.18 and 7.31

C₂ - H₂ and C₆ - H₆ in α-oxidized syringyl units (Sʹ)

G₂

110.8/6.96

C₂ - H₂ in guaiacyl units (G)

D₂

113.3/6.25

C₂ - H₂ in spirodienone substructures (D)

G₅

114.3/6.69, 114.9/6.94

C₅ - H₅ in guaiacyl units (G)

G₆

118.8/6.78

C₆ - H₆ in guaiacyl units (G)

D₆

118.7/6.06

C₆ - H₆ in spirodienone substructures (D)