Characterization and esterification of hemicelluloses from rye straw.
Hemicelluloses were extracted with 10% KOH/0.5% Na(2)B(4)O(7). 10H(2)O from delignified rye straw. Esterification of the hemicelluloses with various acyl chlorides was performed in a homogeneous N,N-dimethylformamide and lithium chloride 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 degrees C for 40 min. Meanwhile, the products were characterized by FT-IR and GPC techniques as well as their solubilities. The molecular mass measurements (31400-123300 g mol(-)(1)) showed only a minimal degradation of the macromolecular hemicelluloses during rapid reactions at 48-75 degrees C for 20-40 min.
Sun
R
R
The BioComposites Centre, University of Wales, Bangor, Gwynedd LL57 2UW, United Kingdom. bicomposites@banfor.ac.uk
Fang
J M
JM
Tomkinson
J
J
D002849:Chromatography, Gas / Q000379:methods; D004952:Esters; D006868:Hydrolysis; D007202:Indicators and Reagents; D019906:Nuclear Magnetic Resonance, Biomolecular; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification; D012434:Secale / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared
D004952:Esters; D007202:Indicators and Reagents; D011134:Polysaccharides; C007916:hemicellulose