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Sulfite cooking of viscose pulp. XV. The effect of xylose on the decomposition of sulfur dioxide solutions

I. Sl√°vik

Slovak Academy of Sciences, Bratislava

 

Abstract: cf. CA 55, 24006e. The effect of xylose on the decompn. of SO2 solns. heated in sealed tubes for 3.5 hrs. at 150° was studied. In buffered solns., the effect of xylose is similar to glucose and furfural; that is, it reduces SO2 to thiosulfates and polythionates, which catalyze the decompn. of SO2. Xylose is oxidized to xylonic acid, but unlike the case of glucose, a sulfonated xylose is also formed. In unbuffered solns., the xylose is dehydrated to furfural which then yields condensation products of the sulfonic acid type. The decompn. of xylose occurs at a higher rate than the decompn. of glucose and at a higher rate in unbuffered than in buffered solns. Apparently, as long as there is sufficient alkali in the sulfite liquor to cause a buffering action, hexoses mainly undergo decompn., whereas pentoses are decompd. in the final cooling stage, when the buffering capacity of the liquor is reduced. In hardwood pulping, where there is a high content of pentoses, the early decompn. of pentoses and its effect on the cooking liquor can be prevented by increasing the buffering capacity of the liquor.

Full paper in Portable Document Format: 161-2a135.pdf (in Slovak)

 

Chemical Papers 16 (1-2) 135–139 (1962)

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