Homogenous reactions of cellulose from different natural sources

Two different homogenous reactions on bacterial cellulose (BC), kenaf fiber(KF) and microcrystalline cellulose (MC) were performed to monitor their chemical reactivity. The first reaction was selective oxidation of the primary hydroxyl group with sodium chlorite in the presence of catalytic amount of sodium chloride. While, the second was the formation of triester hypoiodous cellulose using potassium iodate and potassium iodide. The chemical structures of these derivatives were investigated using FT-IR and solid state C-13 NMR spectroscopies. The BC fibrils required the shortest time among these cellulose samples for both reactions, whereas the viscosity values of BC after iodination and oxidation have the best values compared to KF and MC. FT-IR results show the absence of the hydroxy group of BC and a weak absorption band in both KIF and MC. On the other hand, the crystallinity index (CI) of BC is higher than those of both KF and MC. FT-I R spectra of the oxidized different cellulose samples, confirmed the presence of a strong absorption band at around 1590 cm(-1) that attributed to vibration band of carbonyl group of carboxylic moiety. Moreover, in the C-13 NMR spectrum of oxidized cellulose, the lack of signal at 62 ppm and the appearance of signal at 171 ppm indicated that the primary alcohol group is completely oxidized to carboxylic acid. These results showed that BC had a higher reactivity than other samples due to its great purity and low degree of polymerization. (C) 2008 Elsevier Ltd. All rights reserved.