Determination of Total Hydroxyl Groups

Alternatively, the acetic acid (14) in the hydrolyzate may be converted by treatment with tetrabutylammonium hydroxide (15) solution to tetrabutylam-monium acetate (16). The latter is then transformed to benzyl acetate (18) by treatment with benzyl bromide (17)  

The benzyl acetate (18) is quantitatively determined by capillary column gas chromatography (GC). Benzyl butanoate (20), formed from butanoic acid (19) concurrently with the formation of benzyl acetate (18), serves as the internal standard (Mansson 1983). Since 1 mol of acetic acid (14) is converted to 1 mol of benzyl acetate (18), the total hydroxyl content of the lignin preparation can be determined by quantitative determination of the benzyl acetate (18). The Mansson procedure is a modification of the Bethge-Lindstrom method for determinating O-acetyl groups in acetylated carbohydrates (Bethge and Lindstrom 1973). 

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Determination of Total Hydroxyl Groups 7.1.2.1 Acetylation of the Lignin Preparation... 

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