| 摘要 |
PURPOSE:To prepare the titled novel cellulose having high substitution degree with carboxyalkyl group and acetyl group, by converting the alkali metal salt of a carboxyalkyl cellulose to acid form, and acetylating by the reaction with acetic anhydride. CONSTITUTION:A carboxyalkyl acetyl cellulose having a carboxyalkyl substitution degree of 0.2-2.5 and acetyl substitution degree of 0.5-2.8 is prepared by (1) treating (A) an alkali metal salt of a carboxyalkyl cellulose having a carboxyalkyl substitution degree of 0.2-0.5 (e.g. carboxymethyl cellulose sodium salt) in an aqueous solution of an acid (e.g. sulfuric acid) to convert the salt to an acid, and (2) acetylating the acid with (B) acetic anhydride in the presence of a catalyst (e.g. sulfuric acid). It is preferable to dehydrate the component (A) converted to the acid form, with acetic acid, etc. as far as possible to improve the efficiency of acetylation.
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