Studies on the Vapour Phase Acetylation of Cellulose.(V):Homogeneous Liquid Phase Saponification of the Primary Cellulose Acetate by ZnCl2 Catalyser

摘要

The primary cellulose acetate made by the vapour phase method using ZnCl2 as a catalyser was dissolved in acetic acid containing various amounts of water and ZnCl2, and the solutions were then ripened at various temperatures.From those experiments were obtained the following results:(1) In order to dissolve the primary acetate it is necessary to use acetic acid containing ZnCl2 in at least 7.7% concentration and to increase ZnCl2-concentration as the water content of acetic acid rises. (2) The saponifion velocity is accelerted as the temperature or the concentrations of water and ZnCl2 rise. But the depolymerisation is accelerated with the rise of temperatre or the increase of ZnCl2, and retarded by water. (3) Addition of HCl promotes very much the saponification velocity, and even at room temperture the rpening proceeds with feasible velocity. But excess of HCl also promotes the depolymerisation. (4) When Zn-acetate is added to the ripening solution, it surpresses the action of ZnCl2 or HCl, both the saponification and depolymerisation are stopped, and thus the ripening solution can be kept at a stable state.