Two kinds of regenerated cellulose fiber, high tenacity rayon and polynosic fiber, pretreated in our unique way, were acetylated in fibrous form with sulfoacetic acid catalyst. Results obtained-are as follows:
1. In the presence of free sulfuric acid in the acetylating liquid, high tenacity rayon is hardly acetylated, while polynosic fiber can be acetylated.
2. Impregnated additionally with dioxane or ethanol, the pretreated high tenacity rayon is still kept active toward acetylation. Impregnation with benzene, however, completely removes its reactivity.
3. Impregnated with solvents containing free sulfuric acid the pretreated high tenacity rayon decreases much more in its reactivity than by impregnation with the solvents without sulfuric acid.
4. Impregnated with acetic acid containing sulfuric acid, sulfoacetic acid, perchloric acid or zinc chloride, the pretreated high tenacity rayon unexceptionally decreases in its reactivity.
On the other hand the pretreated polynosic fiber in some cases increases in its reactivity.