Table 2. Semi-Quantitative ¹H–¹³C HSQC NMR Structural Characterization of Fractions from N24 Birch Following Extraction 1 (Figure 2).

	WWE	alkaline	IL/EtOH, H+
Lignin Subunits (%)a
H	0.0	0.0	0.0
G	12.2	23.4	28.2
Gox	0.0	1.5	2.7
S	63.5	59.4	52.8
Sox	12.2	7.9	8.2
S/G	7.2	3.0	2.2
Interunit Linkages (per 100 C9 units)b
β-O-4 aryl ether	43.3	57.8	28.1
β-O-4 aryl ether Cα-etherified	0.0	0.0	29.8
β-5 phenylcoumaran	0.0	2.6	3.2
β–β resinol	3.3	7.1	5.1
total	46.6	67.5	66.2
End-Units (per 100 C9 units)b
cinnamyl alcohol		traces	0.4

^aRelative distribution of lignin subunits (H + G + G_ox + S + S_ox = 100).

^bRelative volume integral of substructure versus volume integral of total lignin subunits.