New iodination of cellulose in phosphoric acid

Microcrystalline cellulose was dissolved at ambient temperature in 85% H3PO4, and KIO3 was added together with KI to the solution thereby obtained. After 24 h, a white product was isolated by adding cold ethanol. The product has a large specific weight and a high content of iodine. On the basis of IR and NMR spectroscopy data, it is suggested that the polymer is the cellulose triester of the unstable acid HOI. A reaction mechanism for the ester formation is proposed.