SynopsisThermal degradation of cellulose model compounds was studied using thermogravimetry (' RI G), electric spin resonance (ESR) spectroscopy, and gas chromatography-mass spectrometry (GS-MS). The molecular weight of samples did not influence the activation energy of gasification. In the case of catalytic influence of NaOH on cellulose thermolysis formation of gaseous products in the temperature range 250-350°C increased and a greater amount of residue was formed at 350-400°C compared to noncatalytic thermolysis. Residues of compounds with hemiacetal groups showed higher concentration of unpaired electrons than residues obtained from models with the blocked hemiacetal group.
Separation of tetroses has been achieved by gas chromatography of their per-O-MesSi oximes on a capillary column coated with OV-17. Trioses could be satisfactorily separated on a packed column with SP-2340 as a stationary phase. The achieved resolution R ^1 fulfills criteria required for quantitative analysis. Mass spectra of the title derivatives are also presented.
SynopsisReduced (4-O-methyl-D-g~ucurono)-D-xy1an and nine methylglycosides related to this polysaccharide were studied by dynamic and isothermal thermogravimetry. It could be stated from the results that the thermal stability of saccharides is increasing with increasing number of pyranose units. The models related to (4-O-methyl-D-glucurono)-D-xylan are more thermally stable than the corresponding hexoglycanic models. Rates of gasification of models containing uronic acid methylesters are higher than those of neutral methylglycosides. The rate of polysaccharide gasification was the highest one from all models studied. The supramolecular structure of polysaccharide is dramatically influencing the course of thermal degradation.
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