Table 3.

Yield and profiles of phenolic compounds of lignins from flax shives as determined by nitrobenzene oxidation.

Substrate	Extraction Conditions	Phenolic Compounds (μmoles/g lignin)								Molar Ratio
		p-BA	VA	SA	VN	SAL	AVN	FA	Total	S/G	H/G
Flax Shives	Unprocessed	36.1 ± 2.5	110.1 ± 8.9	39.4 ± 1.0	1309.2 ± 65.8	358.2 ± 12.1	11.5 ± 0.1	17.5 ± 0.1	1882	0.28	0.025
Flax Shives Lignina	1.25 M NaOH: 80 °C, 5 h	3.3 ± 0.8	29.8 ± 1.2	6.1 ± 1.5	194.7 ± 20.4	46.7 ± 5.5	10.8 ± 5.4	4.6 ± 1.1	296	0.22	0.014
Flax Shives PLPW Extract Ligninb	0.47 M NaOH: 100 °C, 82 min	14.8 ± 4.1	105.9 ± 14.9	28.3 ± 7.1	611.2 ± 44.1	138.5 ± 43.9	N/D	N/D	899	0.23	0.021
	0.47 M NaOH: 140 °C, 82 min	7.4 ± 0.8	82.1 ± 2.9	20.2 ± 1.0	594.7 ± 12.5	134.1 ± 12.6	18.7 ± 1.2	10.3 ± 0.5	868	0.22	0.011
	0.47 M NaOH: 180 °C, 82 min	4.1 ± 0.8	62.5 ± 9.5	14.1 ± 2.5	429.6 ± 98.1	78.1 ± 11.5	20.5 ± 3.6	6.7 ± 1.1	616	0.18	0.01
	Water: 180 °C, 82 min	8.2 ± 0.8	103.6 ± 1.8	25.3 ± 0.5	688.2 ± 19.7	150.6 ± 12.1	N/D	N/D	976	0.22	0.01

N/D: Not Detected. Abbreviations: p-BA, p-hydroxybenzaldehyde; VA, vanillic acid; SA, syringic acid; VN, vanillin; SAL, syringaldehyde; AVN, acetovanillone; FA, ferulic acid; H represents relative total moles of p-hydroxybezaldehyde; G represents relative total moles of vanillic acid, vanillin, and acetovanillone; S represents relative total moles of syringic acid, syringaldehyde. S/G = molar ratio of S to G lignin units; H/G = molar ratio of H to G lignin units.

^aNitrobenzene oxidation was performed with alkali soluble lignin. Lignin was obtained by precipitation at pH 1.5 by addition of 6 N HCl after isolation of the solubilized hemicelluloses;

^bNitrobenzene oxidation was performed with PLPW soluble lignin. Lignin was obtained by precipitation at pH 1.5 by addition of 6 N HCl after isolation of the solubilized hemicelluloses.