Iodine catalyzed esterification of cellulose using reduced levels of solvent

We have developed a novel process for esterification of cellulose with acetic anhydride in the presence of a catalytic amount of iodine to produce cellulose triacetate. At room temperature, 12 h was required for complete esterification which was reduced to 10 min when the reaction was conducted at 100 °C. The production of cellulose triacetate and the degree of substitution was confirmed by NMR analysis and by titration. Both reaction temperature and the amount of iodine influenced the amount of cellulose converted to CTA as well as the molecular weight of the product. Careful characterization of the cellulose triacetate produced in the iodine catalyzed esterification revealed the presence of small amounts of acetylated carbohydrate oligomers which acted as a plasticizer for the cellulose triacetate.