Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment
Abstract
:1. Introduction
2. Results and Discussion
2.1. Sugar Analysis
2.2. Pyrolysis-Gas Chromatography/Mass Spectrometry
2.3. FT-IR Spectra
2.4. Molecular Weight Distribution
2.5. HSQC NMR Spectra
3. Experimental Section
3.1. Materials
3.2. Isolation of Lignins
3.3. Chemical Composition Analysis
3.4. Analytical Pyrolysis
3.5. FT-IR Analysis
3.6. Molecular Weight Analysis
3.7. NMR Spectra
4. Conclusions
Supplementary Information
ijms-14-21394-s001.pdfChemical composition | Untreated bamboo | Pretreated bamboo | ||||
---|---|---|---|---|---|---|
Cellulose (as glucan) | 47.24 ± 1.15 | 52.34 ± 0.32 | ||||
Hemicellulose sugars | 23.85 ± 1.79 | 23.41 ± 0.03 | ||||
Xylan | 22.12 ± 1.53 | 22.53 ± 0.03 | ||||
Arabinan | 1.24 ± 0.23 | 0.68 ± 0.00 | ||||
Galactan | 0.47 ± 0.05 | 0.20 ± 0.00 | ||||
Mannan | 0.07 ± 0.00 | ND | ||||
Galacturonic acid | 0.03 ± 0.01 | ND | ||||
Klason lignin | 23.84 ± 1.09 | 17.27 ± 0.11 | ||||
Acid-soluble lignin | 1.51 ± 0.06 | 1.06 ± 0.02 | ||||
Ash | 1.37 ± 0.03 | 1.16 ± 0.06 | ||||
Samples | Carb a | Ara a | Gal a | Glc a | Xly a | Man a |
MWLu | 10.51 ± 0.25 | 0.22 ± 0.05 | 0.10 ± 0.01 | 6.68 ± 0.05 | 3.49 ± 0.07 | Trace |
MWLp | 8.11 ± 0.87 | 0.04 ± 0.00 | 0.02 ± 0.00 | 6.63 ± 0.71 | 1.43 ± 0.15 | Trace |
EOL | 5.26 ± 0.42 | 0.58 ± 0.05 | 0.32 ± 0.02 | 1.01 ± 0.11 | 3.35 ± 0.22 | Trace |
CEL | 12.24 ± 1.24 | 0.83 ± 0.01 | 0.49 ± 0.02 | 5.17 ± 0.12 | 4.79 ± 0.92 | 0.95 ± 0.22 |
REL | 24.96 ± 1.38 | 0.46 ± 0.03 | 0.92 ± 0.05 | 17.32 ± 0.91 | 4.47 ± 0.30 | 1.47 ± 0.07 |
Label | R.T. (min) | Compound name | Formula | Mw | Untreated | Pretreated |
---|---|---|---|---|---|---|
Carbohydrate derived compounds | ||||||
1 | 2.82 | 2-Cyclopenten-1-one, 2-hydroxy- | C5H6O2 | 98 | 0.9 | 1.6 |
2 | 4.63 | 2-Hydroxy-gamma-butyrolactone | C4H6O3 | 102 | 6.5 | 2.2 |
3 | 5.88 | Furan, 2,5-dimethyl- | C6H8O | 96 | 3.3 | 2.2 |
4 | 6.49 | 2-Furanmethanol | C5H6O2 | 98 | 0.8 | 0.5 |
5 | 7.97 | 2(5H)-furanone | C4H4O2 | 84 | 2.3 | 0.6 |
6 | 8.42 | 2-Cyclopenten-1-one, 2-hydroxy- | C5H6O2 | 98 | 4.5 | 2.3 |
8 | 10.89 | 2-Cyclopenten-1-one, 2-hydroxy-3-methyl- | C6H8O2 | 112 | 0.3 | 0.6 |
9 | 11.20 | 1,2-Cyclopentanedione, 3-methyl- | C6H8O2 | 112 | 1.8 | 0.6 |
13 | 13.87 | 2,4(3H,5H)-furandione, 3-methyl- | C5H6O3 | 114 | 1.4 | 1.1 |
17 | 16.38 | 2-Furancarboxaldehyde, 5-(hydroxymethyl)- | C6H6O3 | 126 | 1.1 | 2.3 |
28 | 22.67 | β-D-Glucopyranose, 1,6-anhydro- | C6H10O5 | 162 | 21.0 | 65.8 |
Sum | 43.9 | 79.9 | ||||
Lignin guaiacyl-type | ||||||
10 | 12.00 | Phenol, 2-methyl- | C7H8O | 108 | 1.2 | 0.4 |
12 | 12.85 | Phenol, 2-methoxy- | C7H8O2 | 124 | 1.5 | 0.4 |
14 | 15.49 | Phenol, 2-methoxy-4-methyl- | C8H10O2 | 138 | 0.9 | 0.3 |
15 | 15.59 | 1,2-Benzenediol | C6H6O2 | 110 | 1.8 | 0.5 |
20 | 17.80 | 1,2-Benzenediol, 4-methyl- | C7H8O2 | 124 | 0.9 | 0.5 |
21 | 18.37 | 2-Methoxy-4-vinylphenol | C9H10O2 | 150 | 2.8 | 0.9 |
24 | 20.25 | Vanillin | C8H8O3 | 152 | 1.1 | 0.4 |
25 | 21.23 | 1,2,4-Trimethoxybenzene | C9H12O3 | 168 | 0.7 | 0.4 |
26 | 21.37 | Phenol, 2-methoxy-4-(1-propenyl)- | C10H12O2 | 164 | 1.2 | 0.4 |
27 | 22.07 | Ethanone, 1-(4-hydroxy-3-methoxyphenyl)- | C9H10O3 | 166 | 1.6 | 0.3 |
30 | 22.92 | 2-Propanone, 1-(4-hydroxy-3-methoxyphenyl)- | C10H12O3 | 180 | 0.4 | Trace |
36 | 25.27 | 2-Butanone, 4-(4-hydroxy-3-methoxyphenyl)- | C11H14O3 | 194 | 0.5 | 0.2 |
40 | 26.84 | 2-Propenal, 3-(4-hydroxy-3-methoxyphenyl)- | C10H10O3 | 178 | 1.6 | 0.2 |
41 | 26.94 | 4-((1E)-3-Hydroxy-1-propenyl)-2-methoxyphenol | C10H12O3 | 180 | 6.4 | 0.4 |
Sum | 22.7 | 5.3 | ||||
Lignin syringyl-type | ||||||
18 | 17.08 | 1,2-Benzenediol, 3-methoxy- | C7H8O3 | 140 | 1.1 | 0.3 |
22 | 19.17 | Phenol, 2,6-dimethoxy- | C8H10O3 | 154 | 1.9 | 0.4 |
29 | 22.82 | Benzene, 1,2,3-trimethoxy-5-methyl- | C10H14O3 | 182 | 0.5 | Trace |
32 | 23.63 | 3′,5′-Dimethoxyacetophenone | C10H12O3 | 180 | 2.4 | 0.7 |
37 | 25.43 | Benzaldehyde, 4-hydroxy-3,5-dimethoxy- | C9H10O4 | 182 | 0.9 | 0.4 |
38 | 26.25 | Phenol, 2,6-dimethoxy-4-(2-propenyl)- | C11H14O3 | 194 | 1.6 | 0.5 |
39 | 26.76 | Ethanone, 1-(4-hydroxy-3,5-dimethoxyphenyl)- | C10H12O4 | 196 | 0.7 | 0.3 |
43 | 30.25 | 3,5-Dimethoxy-4-hydroxycinnamaldehyde | C11H12O4 | 208 | 0.6 | 0.4 |
Sum | 9.7 | 3.1 | ||||
Other lignin derived products | ||||||
7 | 10.01 | Phenol | C6H6O | 94 | 1.4 | 0.5 |
11 | 12.57 | Phenol, 3-methyl- | C7H8O2 | 108 | 1.0 | 0.5 |
16 | 16.19 | 4-Methyl-benzaldehyde | C8H8O | 120 | 10.0 | 2.6 |
19 | 17.52 | Hydroquinone | C6H6O2 | 110 | 0.9 | 0.2 |
23 | 19.47 | Benzaldehyde, 4-hydroxy- | C7H6O2 | 122 | 0.7 | 0.3 |
31 | 23.31 | 4-Acetylbenzoic acid | C9H8O3 | 164 | 0.9 | 1.2 |
33 | 23.69 | 1,4-Benzenedicarboxylic acid, methyl ester | C9H8O4 | 180 | 0.9 | 1.3 |
34 | 24.07 | trans-Cinnamic acid | C9H8O2 | 148 | 0.3 | 0.1 |
35 | 25.07 | 1,4-Benzenedicarboxylic acid | C8H6O4 | 166 | 0.9 | 0.6 |
Sum | 16.8 | 7.4 | ||||
S/G | 0.4 | 0.6 |
Heading | MWLu | MWLp | EOL | CEL |
---|---|---|---|---|
Mw (g/mol) | 7692 | 10657 | 5873 | 15307 |
Mn (g/mol) | 4406 | 5997 | 3072 | 9721 |
Mw/Mn | 1.75 | 1.78 | 1.91 | 1.57 |
Labels | δC/δH (ppm) | Assignment |
---|---|---|
Lignin cross-signals | ||
Cβ | 53.2/3.43 | Cβ–Hβ in β-5′ (phenylcoumaran) substructures (C) |
Bβ | 53.5/3.05 | Cβ–Hβ in β-β′ (resinol) substructures (B) |
–OMe | 55.9/3.72 | C–H in methoxyls (MeO) |
Aγ | 60.1/3.22 and 59.67/3.59 | Cγ–Hγ in β-O-4′ substructures (A) and others |
Iγ | 61.4/4.09 | Cγ–Hγ in cinnamyl alcohol end-groups (I) |
A′γ | 62.8/4.28 | Cγ–Hγ in γ-acylated β-O-4′ substructures (A′) |
Cγ | 62.4/3.71 | Cγ–Hγ in β-5′ (phenylcoumaran) substructures (C) |
I′γ | 64.1/4.77 | Cγ–Hγ in γ-acylated cinnamyl alcohol end-groups (I′) |
Aα | 72.4/4.85 | Cα–Hα in β-O-4′ substructures (A) |
Bγ | 71.0/4.17 and 70.9/3.80 | Cγ–Hγ in β-β′ (resinol) substructures (B) |
Aβ(G) | 83.6/4.30 | Cβ–Hβ in β-O-4′ substructures linked to a guaiacyl unit (A) |
Cα | 87.1/5.45 | Cα–Hα in β-5′ (phenylcoumaran) substructures (C) |
Aβ(S) | 85.8/4.10 | Cβ–Hβ in β-O-4′ substructures linked to a syringyl unit (A, erythro) |
Aβ(S) | 86.2/3.99 | Cβ–Hβ in β-O-4′ substructures linked to a syringyl unit (A, threo) |
Bα | 84.7/4.65 | Cα–Hα in β-β′ (resinol) substructures (B) |
T′2/6 | 103.9/7.32 | C′2,6–H′2,6 in tricin (T) |
T3 | 106.1/7.04 | C3–H3 in tricin (T) |
T6 | 98.8/6.22 | C2,6–H2,6 in tricin (T) |
S2/6 | 104.3/6.70 | C2,6–H2,6 in syringyl units (S) |
S′2/6 | 106.3/7.30 | C2,6–H2,6 in oxidized (CαOOH) syringyl units (S′) |
G2 | 111.1/6.97 | C2–H2 in guaiacyl units (G) |
G5 | 115.8/6.69 | C5–H5 and C6–H6 in guaiacyl units (G) |
G6 | 119.1/6.79 | C6–H6 in guaiacyl units (G) |
PCA7 | 144.5/7.43 | C7–H7 in p-coumaroylated substructures (PCA) |
PCA2/6 | 130.2/7.46 | C2.6–H2.6 in p-coumaroylated substructures (PCA) |
PCA3/5 | 115.4/6.76 | C3–H3 and C5–H5 in p-coumaroylated substructures (PCA) |
PCA8 | 113.6/6.26 | C8–H8 in p-coumaroylated substructures (PCA) |
FA2 | 111.5/7.49 | C2–H2 in ferulate (FA) |
H2/6 | 128.0/7.17 | C2.6–C2.6 in p-hydroxyphenyl units (H) |
H3/5 | 115.2/6.57 | C3.5–C3.5 in p-hydroxyphenyl units (H) |
Jα | 153.5/7.61 | Cα–Hα in cinnamyl aldehyde end-groups (J) |
Jβ | 126.2/6.79 | Cβ–Hβ in cinnamyl aldehydes end-groups (J) |
D′β | 80.3/4.54 | C′β–H′β in spirodienone substructure (D) |
Polysaccharide cross-signals | ||
X2 | 70.1/3.33 | C2–H2 in β-d-xylopyranoside |
X3 | 72.0/3.42 | C3–H3 in β-d-xylopyranoside |
X4 | 75.3/3.54 | C4–H4 in β-d-xylopyranoside |
X5 | 62.8/3.40 | C5–H5 in β-d-xylopyranoside |
MWLu (%) | MWLp (%) | EOL (%) | CEL (%) | |
---|---|---|---|---|
Lignin interunit linkages | ||||
β-O-4′ substructure (A) | 89.4 | 82.1 | 72.3 | 94.5 |
β-β′ resinol substructures (B) | 5.5 | 2.6 | 20.0 | 0 |
β-5′ phenylcoumaran substructures (C) | 5.1 | 15.3 | 7.7 | 5.5 |
Lignin aromatic units | ||||
H | 3.5 | – | 19.6 | 8.0 |
G | 49.5 | 48.5 | 42.4 | 47.5 |
S | 47.0 | 51.5 | 38.0 | 44.5 |
S/G ratio | 0.95 | 1.06 | 0.90 | 0.94 |
p-Hydroxycinnamates | ||||
p-Coumarates | 97.5 | 84.9 | 82.1 | 76.6 |
Ferulates | 9.3 | 15.1 | 17.9 | 23.4 |
p-Coumarates/ferulates ratio | 9.75 | 5.62 | 4.59 | 3.27 |
Acknowledgments
Conflicts and Interest
References
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Bai, Y.-Y.; Xiao, L.-P.; Shi, Z.-J.; Sun, R.-C. Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment. Int. J. Mol. Sci. 2013, 14, 21394-21413. https://doi.org/10.3390/ijms141121394
Bai Y-Y, Xiao L-P, Shi Z-J, Sun R-C. Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment. International Journal of Molecular Sciences. 2013; 14(11):21394-21413. https://doi.org/10.3390/ijms141121394
Chicago/Turabian StyleBai, Yuan-Yuan, Ling-Ping Xiao, Zheng-Jun Shi, and Run-Cang Sun. 2013. "Structural Variation of Bamboo Lignin before and after Ethanol Organosolv Pretreatment" International Journal of Molecular Sciences 14, no. 11: 21394-21413. https://doi.org/10.3390/ijms141121394