MODIFICATION OF NATURAL POLYMERS BY THERMO-MECHANICAL PROCESSING
Location: Plant Polymer Research
Title: IODINE CATALYZED ESTERIFICATION OF CELLULOSE USING REDUCED LEVELS OF SOLVENT
Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 5, 2006
Publication Date: January 20, 2007
Citation: Biswas, A., Selling, G.W., Appell, M.D., Woods, K.K., Willett, J.L., Buchanan, C.M. 2007. Iodine catalyzed esterification of cellulose using reduced levels of solvent. Carbohydrate Polymers. 68(3):555-560.
Interpretive Summary: Starch and cellulose, earth's most abundant biopolymers, are of tremendous economic importance. Over 90% of cotton and 50% of wood are made of cellulose. Wood and cotton are the major resources for all cellulose products such as paper, textiles, construction materials, cardboard, as well as such cellulose derivatives as cellophane, rayon, and cellulose acetate. Similarly, acetylated starches have been known for over 100 years and have found applications. However, cellulose acetates are industrially more important and it is estimated that annually 1.5 billion pounds of cellulose acetates are manufactured globally. Cellulose acetate is widely used in textiles because of its low cost, toughness, gloss, high transparency, natural feel, and other favorable aesthetic properties. Cellulose acetate fibers in cigarette filters are designed to absorb vapors and accumulate particulate smoke components. Cellulose acetate is also used as a carrier for photographic negatives, motion picture film (celluloid), microfilm, microfiche and audio tape. We would like to report a simple rapid method to acetylate cellulose. We have found that acetic anhydride in the presence of catalytic amount of iodine is an excellent acylating reagent for cellulose. It is believed that iodine activates the carbonyl group of acetic anhydride, which renders it more reactive. Thus, iodine-activated acetic anhydride is a strong enough acylating agent to react with cellulose directly. This reagent works only in the absence of a solvent. Furthermore, when cellulose was heated with acetic acid and iodine, there was no reaction and cellulose remained unreacted. This low solvent method that we discovered would help the cellulose acetate manufacturers to prepare cellulose acetate in an environment friendly way. This method reduces the use of solvents and acids.
A novel method for the preparation of cellulose acetate is described herein, involving the concurrent use of iodine and acetic anhydride. The method is simple, rapid, efficient, and solvent-less. With this method, cellulose acetates have been synthesized.