Table 4.
Assignment of 13 C- 1 H cross-signals in the HSQC spectra of lignin
| Labels | δC/δH (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 |
| Aγ |
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”) |
| Cγ |
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”) |
| Dα |
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”) |
| Cα |
85.4/4.64 |
Cα-Hα in β-β (resinol) substructures (C) |
| Dα’ |
85.4/4.80 |
Cα’-Hα’ in β-1 (spirodienone) substructures (D) |
| Aβ |
86.5/4.10 |
Cβ-Hβ in γ-OH β-O-4 substructures (A) |
| Bα |
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 | Cα’-Hα’ in p-coumaroylated substructures (A”) |