Preparation of Cellulose 2,5-Acetate

Into the other half of the primary solution,50 ml of 70% acetic acid at 60 °C and 0.14 ml of concentrated sulfuric acid are slowly added with stirring,in order to bring about partial saponification of the cellulose triacetate.The stoppered bottle is held at 80 °C for 

3 h and then worked up as described for cellulose triacetate. Yield 6-6.5 g. Cellulose 2,5-acetate (acetyl group content 40%) is soluble in acetone and methylene chlo-ride/methanol (volume ratio 9 1). 

The progress of the partial saponification can be checked by a simple solubility test. About 1 ml of the solution is withdrawn and the cellulose acetate precipitated with water. The small sample is quickly washed free of acid and dried as much as possible by pressing between two filter papers. Some fibers of the still damp material are placed in a test tube with 15-20 ml oholuene/ethanol (volume ratio 1 1) and heated to boiling in a water bath. If the fibers go into solution, then after about 15 min the whole charge can be worked up as described above. 

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