On the Reaction between Spruce Wood Meal and Hydroxylamine Hydrochloride Solution in Ethanol (pH 2.5)

Studies on the Sulphite Cooking. Part 3

Abstract

Extracted spruce wood meal, spruce holocellulose and rayon pulp were cooked with NH₂OH•HCl solution in ethanol (pH 2.5) in the boiling water bath during 1_??_20 hrs. Acetal linkages in these materials are hydrolyzed and the liberated carbonyl groups make oxime with the production of equivalent HCl. The curves (produced HCl-reaction time) for holocellulose and rayon pulp were linear, whereas in the case of spruce wood the rate of HCl production was very rapid in the earlier stage and the curve turned to straight line after about 8 hours. Extraporating the latter to time zero, it was concluded that 1g wood meal liberated 0.3 m-mol HCl within a few earlier hours. The present authors suppose that this 0.3 m-mol HCl per g wood must be produced by cleavage of acetal linkages between carbonyl group of lignin and carbohydrates, and therefore lignin has 1 mole carbonyl group per 960g.