羟丙基甲基纤维素醋酸酯与丙酸酯的合成

Synthesis of Hydroxypropyl Methycellulose Acetate and Hydroxypropyl Methycellulose Propionate

以羟丙基甲基纤维素（HPMC）为原料,醋酸酐、丙酸酐为酯化剂,在吡啶中进行酯化反应制备了羟丙基甲基纤维素醋酸酯和羟丙基甲基纤维素丙酸酯。通过改变体系的溶剂用量,得到了具有较好性状和取代度的产物,采用滴定法测定了取代度,并对产物进行表征和性能测试。结果表明,反应体系在110℃下反应1~2.5 h,反应后选用去离子水为沉淀剂,可得到取代度大于1（理论取代度为2）的粉末状产物,两种产物在乙酸乙酯、丙酮、丙酮/水等多种有机溶剂中溶解性较好。

Hydroxypropyl methylcellulose acetate and hydroxypropyl methylcellulose propionate were synthesized from hydroxypropyl methylcellulose（ HPMC）,during the process of which propionic anhydride and acetic anhydride were used as esterifying agent and pyridine as organic solvent. By varying the amount of solvent,products with preferable character and degree of substitution（ DS） were prepared. The degree of substitution was determined by titration. The structure and properity of products were characterized and tested. The results indicate that the reaction system were heated at 110 ℃ for1 h ~ 2. 5 h,and after heating distilled water was used as the precipitation agent to get the precipitate. Powder products with the degree of substitution greater than 1（ theoretically it is 2） were obtained. And both products have good solubility in the organic solvents of ethyl acetate,acetone and acetone / water.