Acid and Alkali Hydrolyses of Polyhydroxy Polymer Sulfates

TANAKA Hiroo, SENJU Ryoichi

doi:10.1246/nikkashi.1974.359

The alkali hydro1yses of starch sulfates, cellulose sulfates, and sulfated poly(vinyl alcohols) (PVS) having various degrees of substitutions(DS) and the acid hydrolyses of PVS have been investigated kinetipa11y in aqueous solution from the stand point of polymer reaction. In both acid and alkali hydrolyses, the rates of reactions did not follow the simple kinetic equation and the apparent rate constants decreased with a progress of the reaction. For exelmple, the following equation could be used for the acid hydrolyses of PVS: k(at 900C)=1.5*10 -4+3.02*10 SC*(DS)2, O (1/mol.sec) Even in alkali hydrolyses, thereactivities decreased also with a progress of reaction. But the initial rate constants became signifigantly larger with decreasing DS in contrast to the acid hydrolyses. These abnormal phenomena eould mainly be explained in terms of themutual interaction between the polymers and catalysts. In acid hydrolyses, sulfate groups, existed in high density, reacted rapidly because of the adsQrptionof, catalyst(H ) caused by sulfate group. As the adsorptien effects decreased with a progress of reaction, the reactivities decreased gradually. In alkali hydrolyses, sulfate groups, existed in low density, reacted rapidly because of the adsorption of catalyst OH caused by free hydroxyl group and the repulsion by sulfate group. Accordingly, the initial rates were large in sulfates of low DS. However, the distribution of residual sulfate groups became gradually heterogeneously (in a cluster) and the Teactivities decreased.

Acid and Alkali Hydrolyses of Polyhydroxy Polymer Sulfates

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