Homogeneous Acetylation of Cellulose in the New Solvent Triethyloctylammonium Chloride in Combination with Organic Liquids

In the context of our studies on new cellulose solvents, triethyloctylammonium chloride (N2228Cl) in combination with acetone and N,N-dimethylacetamide (DMAc) has been investigated for homogeneous acetylation of cellulose. In addition to the new solvent systems, the reaction has also been examined in 1-butyl-3-methylimidazolium chloride (BMIMCl) and LiCl/DMAc to determine the influence of the different solvents on the degree of substitution (DS). By reaction of dissolved cellulose with acetyl chloride (AC) or acetic anhydride (AA) at comparable reaction conditions and by applying different molar ratios, cellulose acetates (CA) with different DS have been obtained. The analysis of the samples by NMR spectroscopy reveals a functionalization mainly in the order O-6 > O-2 > O-3. The cellulose acetates synthesized by reaction with AC reveal similar DS values compared to samples prepared in the solvents LiCl/DMAc and BMIMCl. On the contrary, using AA as acylation agent results in lower DS values depending on the solvent applied.