AbstractThe effect of activation of cellulose by ammonia is surveyed with regard to an increase of accessibility of different cellulose structures to subsequent reactions proceeding in an alkaline medium, causing considerable swelling by itself. Special subjects were the reactions of xanthogenation, carboxymethylation, and cyanoethylation. In all these heterogeneous reactions a considerable increase in the reaction rate and degree of conversion was found.Using the emulsion xanthogenation with a stepwise enlargement of NaOH concentration as a method of accessibility measurement, considerable changes of the accessibility spectrum of different cellulose structures were found after activation with liquid ammonia or aqueous solutions of ammonia at high concentration. In all the cases investigated, the activation brings about a considerable broadening of the accessibility distribution.