Influence of Ethanol Organosolv Pulping Conditions on Physicochemical Lignin Properties of European Larch

Table 4

Functional group content of the larch organosolv samples. PhOH-, AlkOH-, and MeO contents were determined via ¹H NMR and COOH content via ³¹P NMR.

	CSF	PhOH^a (mmol·g^−1)	AlkOH (mmol·g^−1)	Total OH (mmol·g^−1)	PhOH/AlkOH ratio	MeO (mmol·g^−1)	COOH (mmol·g^−1)
OS-A	1.65	3.15	4.15	7.30	0.76	6.27	0.09
OS-B	1.80	3.45	3.91	7.36	0.88	6.05	0.07
OS-C	1.95	3.50	3.72	7.22	0.94	5.92	0.07
OS-D	1.93	3.47	3.73	7.20	0.93	5.77	0.07
OS-E	2.10	3.74	3.60	7.34	1.04	6.09	0.09
OS-F	2.24	3.91	3.51	7.42	1.11	5.71	0.09
OS-G	2.42	4.15	3.25	7.40	1.28	6.01	0.1
AC-OS	—	3.60	5.05	8.65	0.71	4.78	0.2
MWL	—	3.08	6.04	9.12	0.51	4.16	—^b

^aPhOH, phenolic hydroxyl groups; AlkOH, aliphatic hydroxyl groups; MeO, methoxyl groups; COOH, carboxylic acid groups. ^bNot analyzed via ³¹P NMR.