Journal of Spectroscopy / 2017 / Article / Tab 2

Review Article

Structural Characterization of Lignin and Its Degradation Products with Spectroscopic Methods

Table 2

Assignments of signals in FTIR spectrum to functional groups in lignin [25, 29, 38].

Wavenumbers/cm−1AssignmentsFunctional groups and structures in lignin

3400–3600v (O-H)Free -OH
3100–3400v (O-H)Associated -OH
2820–2960v (C-H)-CH2, -CH3
2920v (C-H)Carboxylic -OH
2650–2890v (C-H)Methyl group in methoxyl
1771v (C = O)Aromatic
1700–1750v (C = O)Unconjugated ketones, carbonyls, and ester groups
1722v (C = O)Aliphatic
1650–1680v (C = O)Conjugated p-substituent carbonyl and carboxyl
1500–1600, 1420–1430v (aromatic skeletal)Benzene ring
1450–1470, 1360–1370v (C-H)-CH2, -CH3
1325–1330, 1230–1235v (C-O)Syringyl ring
1270–1275v (C-O)Guaiacyl ring
1215v (C-O)Ether
1140–1145v (C-H)Guaiacyl
1130v (C-H)Syringyl
1085–1090v (C-O)Secondary alcohol and aliphatic ether
1025–1035v (C-O, C-H)Aromatic ring and primary alcohol
750–860v (C-H)Aromatic ring

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