Characterization and esterification of hemicelluloses from rye straw

Hemicelluloses were extracted with 10% KOH/0.5% Na2B4O7. 10H(2)O from delig nified rye straw. Esterification of the hemicelluloses with various acyl ch lorides was performed in a homogeneous N,N-dimethylformamide and lithium ch loride system using 4-(dimethylamino)pyridine catalyst and triethylamine as a neutralizer. The degree of substitution was controlled between 0.37 and 1.65. Under an optimum condition (sample 14, molar ratio 3:1), >90% of the free hydroxyl groups in native hemicelluloses were stearoylated at 75 degre es C for 40 min. Meanwhile, the products were characterized by FT-IR and GP C techniques as well as their solubilities. The molecular mass measurements (31400-123300 g mol(-1)) showed only a minimal degradation of the macromol ecular hemicelluloses during rapid reactions at 48-75 degrees C for 20-40 m in.