Table 1: Signal in the infrared region for precipitated lignins.

Signal (cm−1) Functional groupMaximum of the signal (cm−1)
LALLN-HClLLN-CH3COOHLLN-H3PO4

3440–3430ν O–H (hydrogen bonding)3408,03440,03439,63438,1
2940–2930
2689–2880
ν C–H aliphatic (groups CH and CH2)
ν C–H (groups CH3 from OCH3)
2937,4
(Overlapped)
2940,3
2846,7
2939,0
2847,0
2938,0
2846,0
1727–1690ν C=O (Very weak)1710,71710,81710,9
1647,11648,11649,1
1610–1690ν C=C aromatic1598,91610,71608,01609,8
1505γ C–H aromatic on the plane1512,11512,11510,11510,0
1458γ C–H aliphatic (groups CH or CH2)1458,11460,01459,01459,8
1425–1420γ C–H aliphatic (groups CH3)1429,21425,31422,314245,8
1370–1250γ O–H1369,41367,41367,11367,5
ν C–O (syringyl ring)1220,91218,91219,01218,1
1260ν C–O (guaiacyl ring)1271,01269,11269,91269,9
1160–1140ν C–O (secondary alcohol)1126,41120,61125,61125,0
1044ν C–O (primary alcohol)1033,81033,81033.81033.8
844γ C–H aromatic outside the plane (wide)858,6860,2860,2860,2
620ν C–Cl (hydrochloric acid)615

Reference signals (Aldrich lignin) in lignin (as discussed elsewhere [10]).