CHARACTERIZATION BY NUCLEAR MAGNETIC RESONANCE OF ACETILATED BACTERIAL CELLULOSE IN DIMETILACETAMIDE/ LITHIUM CHLORIDE

Lima, G. M.; Tischer, C. A.

University of Vale of Itajai, Itajai, Brazil.

The cellulose is used as paper, textiles and other industrial products, purified or as a chemical derivative, that eventually involve dissolution. Many solvents or mixtures can be used to do it properly, with or without high temperature, depending of composition of wood source. The bacterial cellulose mainly produced by Acetobacter xylinum, has glucose molecules linked ß-(1à4) as well the vegetal one, but free of lignin and hemicelluloses, dispending severe chemical processes of purification. The main goal of these work was dissolute and produce a acetylated cellulose using a dimethilacetamide/acetic anhydride and characterize the acetylated derivatives through nmr mono and bidimensional. The process was optimized, with the dissolution of the bacterial cellulose in dimetilacetamide/lithium chloride solution, at 120 °C, 150 °C, or 170 °C. After 24h or 48h, a range of 1.5 to 25 mL of acetic anhydride were added and warmed to 110 °C followed by 72 h of dialysis through water. The cellulose acetates were identified with infra-red spectroscopy, and the best result was 43% (w/w) of derivative. The 1H-nmr show the proton resonance of the per acetylated glucose ring (d ~ 2,60-5,20 ppm) and the corresponding methyl protons of the acetate group (d ~ 1,80-2,20 ppm). The 13C resonance corresponding to the C6>>C2>C3 appear at d ~ 60-80 ppm and to the C1 at d ~ 101 ppm. The derivatization of the bacterial cellulose is applicable for the polymer characterization, or can be useful for textile fibers. The authors like to thanks to FAPESC and Nanoglicobiotec/CNPq by the financial support. Word-keys: Bacterial cellulose, dimetilacetamida, anhydride, Nuclear Magnetic Resonance.