Table 5. Functional Groups Content for Selected Lignins Isolated Using Acid-Free Organosolv Treatments (A20 Series). Data Have Been Derived by Quantifying HSQC Spectra on the Basis of Quantitative 13C NMR Measurements35,40.
| motif | A20-1 [mmol/g] | A20-3 [mmol/g] | A20-4 [mmol/g] | A20-6 [mmol/g] | A20-7 [mmol/g] | A20-9 [mmol/g] | A20-10 [mmol/g] | A20-12 [mmol/g] |
|---|---|---|---|---|---|---|---|---|
| G-ring (HSQC) | 0.12 | 0.10 | 0.39 | 0.23 | 0.11 | 0.09 | 0.06 | 0.04 |
| S ring (HSQC) | 0.58 | 0.62 | 0.73 | 0.67 | 0.27 | 0.22 | 0.54 | 0.57 |
| -OMe (13C) | 8.72 | 8.34 | 8.29 | 9.22 | 7.51 | 7.16 | 8.07 | 7.05 |
| Quat. Phe C-OMe (13C) (V) | 8.72 | 8.12 | 9.24 | 10.12 | 8.40 | 7.76 | 9.27 | 9.42 |
| β-O-4′ (G) (HSQC) (A) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| β-O-4′ (S) (HSQC) (B) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| β-β′ (HSQC) (C) | 0.07 | 0.05 | 0.11 | 0.09 | 0.08 | 0.07 | 0.07 | 0.04 |
| β-5′ (HSQC) (D) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| β-d-Xylanopyr. (HSQC) (G) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| BE (HSQC) (F) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 |
| furan C3 type 1 (HSQC)a (I, II, III) | 1.08 | 0.72 | 2.78 | 1.13 | 0.54 | 0.49 | 0.65 | 0.64 |
| furan C4 type 1 (HSQC) (I, II, III) | 0.32 | 0.26 | 0.70 | 0.55 | 0.21 | 0.24 | 0.29 | 0.37 |
| furan C3 type 2 (HSQC) (IVa, IVb, V) | 0.44 | 0.38 | 1.08 | 0.95 | 0.39 | 0.48 | 0.65 | 0.76 |
| furan C4 type 2 (HSQC) (IVa, IVb, V) | 0.12 | 0.13 | 0.42 | 0.51 | 0.20 | 0.27 | 0.40 | 0.44 |
| ketone (13C) (III) | 0.03 | 0.31 | 0.05 | 0.12 | 0.21 | 0.40 | 0.16 | 0.47 |
| ester (13C) (E) | 0.00 | 0.00 | 0.00 | 0.00 | 0.00 | 0.01 | 0.01 | 0.02 |
| furan aldehyde (HSQC) (I, IVa, IVb) | 0.07 | 0.14 | 0.14 | 0.32 | 0.20 | 0.34 | 0.47 | 0.47 |
| S:G (pyr-GC/MS) | 83:17 | 86:14 | 65:35 | 74:26 | 71:29 | 71:29 | 90:10 | 93:7 |
a
Potential overlap. Furan C3,4 and overlap with substituted G. Not included in the Phe/fur ratio (HSQC).