synopsisA bleached sulfite pulp (85.0% a-cellulose) was dissolved in dimethylformamide containing anhydrous chloral and pyridine as catalyst. The clear cellulose solution was then reacted with acetic anhydride under various conditions. The reaction products contained both acetyl groups and chlorine in amounts varying from 20% to 38%. Curves of reaction rates with respect to chlorine and acetyl groups under various conditions of temperature and reactant ratios were similar in appearance, and all the products contained approximately 2 moles of acetyl groups per mole of chloral. Yields varied from 180% after treatment at room temperature (25OC) for 1 hr to 250% after 4 hr. The products could be hydrolyzed in acid with some difficulty but very easily in dilute alkali.Films cast from acetone solutions had higher permittivity and lower a.c. conductivity than similar films made from cellulose diacetate.The products had low flammability and hygroscopicity. INTRODUCTIONIt was recently reported that cellulose could be dissolved in dimethyl sulfoxide, dimethylformamide (DRIF) , dimethylacetamide, and N-methyl-2-pyrrolidone in the presence of 5-10 moles anhydrous chloral per glucose residue.' These solutions were found to be miscible with synthetic high polymers. Tepteleva2 reported on the reaction of free hydroxyl groups in cellulose acetate with chloral in methylene chloride and in chloroform. I n DMF, little reaction was found to take place. In previous work,3 modified cellulose triacetates were prepared by reacting either secondary cellulose acetate or cellulose with chloral in methl lene chloride, benzene, or acetic acid followed by acetylation of the reaction product in the same reaction medium. Products with interesting properties were obtained containing up to 17% chlorine.I n the present work, cellulose was first dissolved in DMF containing chloral and pyridine and reacted with a mixture of acetic anhydride and pyridine. Reaction rates were studied and the products were characterized as to their acetyl and chlorine contents, elementary composition, and degree of polymerization (D.P.). The anhydrous chloral (bp 97-98"C), acetic anhydride, methylene chlolose was used. dried, and fluffed in a small hammer mill. 2773vacuum a t 60°C. could also be used as a medium for the reactions described in this work.ride, acetic acid, and pyridine used were reagent-grade chemicals. AnalysesChlorine analyses were carried out by the microcombustion method described by White.4Acetyl groups were determined by a modification of the semimicromethod described by Lin and S c h~e r c h .~ A sample (20-30 mg) was weighed into a 25-ml flask. Then, 3 ml of 7Oy0 2,2,2-trifluoroethanol solution containing 0.195 meq/ml sodium hydroxide was added to the sample, and the flask was heated loosely stoppered for 10 min at 60°C. Pyridine, 3 ml, was then added, and the solution was saponified for 3 hr a t 60°C. The excess alkali was back-titrated to a phenolphthalein endpoint with 0.05 N HCI. Blanks were run with every batch of samples.The D.P. of the ori...
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