Oleoylation of wheat straw hemicelluloses in new homogeneous system

Oleoylated hemicelluloses with degrees of substitution between 0.24 and 1.6 7 were prepared by a rapid esterification of wheat straw hemicelluloses wit h oleoyl chloride using 4-dimethylaminopyridine as a catalyst and triethyla mine as a neutralizer in homogeneous N,N-dimethylformamide and lithium chlo ride system. The effects of oleoyl chloride concentration, reaction duratio n, and triethylamine concentration have been studied. Under an optimum cond ition (sample 12, molar ratio 1:3), over 90% of the free hydroxyl groups in native hemicelluloses were oleoylated in 35 min at 75 degrees C. The new m aterials were characterized by FT-IR, GPC, and thermal analysis. The molecu lar weight measurements (39700-110900) showed only a minimal degradation of hemicellulosic chains during the rapid reactions at 75 degrees C for 15-40 min.