- 1H-nuclear magnetic resonance spectroscopy of reducing-residue anomeric protons of pertrifluoroacetylated carbohydrates.
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Eight monosaccharides (L-arabinoside, L-fucose, D-galactose, D-glucose, D-lyxose, D-mannose, L-rhamnose, and D-xylose), eight disaccharides (cellobiose, gentiobiose, isomaltose, lactose, maltose, nigerose, sophorose, and xylobiose), and three trisaccharides (isomaltotriose, maltotriose, and xylotriose) were derivatized with N-methylbis-(trifluoroacetamide) in pyridine solution to form trifluoroacetylated derivatives. These were analyzed by 1H-n.m.r. spectroscopy to determine the characteristics of the spectra and distributions of the reaction products. Peaks corresponding to reducing-residue anomeric protons were located significantly downfield of all others, and were in general 0.4 p.p.m. or more downfield of equivalent signals from the same carbohydrates when they were free or derivatized with other groups. Neither the location of anomeric proton peaks relative to each other nor the degree of spin-spin coupling between H-1 and H-2 varied greatly with type of derivatization. Spin-spin coupling, however, decreased for some beta-pyranose forms of xylobiose and the three trisaccharides. In all examples except some where H-2 was oriented equatorially to a pyranose ring, the proportion of the alpha-pyranose was either enhanced or not changed in concentration by trifluoroacetylation.
- Summerfelt,Selosse,Reilly,Trahanovsky
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p. 163 - 172
(2007/10/02)
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- IMPROVED GAS CHROMATOGRAPHIC SEPARATION OF ENANTIOMERIC CARBOHYDRATE DERIVATIVES USING A NEW CHIRAL STATIONARY PHASE
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Pentylated cyclomaltohexaose ( α-cyclodextrin ) can be used as a chiral stationary phase for cappilary g.l.c. in the range 40 deg to > 200 deg.Strong enantioselective molecular interactions are observed towards trifluoroacetylated carbohydrates, methyl glycosides, 1,4- and 1,5-anhydroalditols, polyols, and polyhydroxy acid methyl esters.Base-line resolution of enantiomers is achieved after only a few minutes.
- Koenig, Wilfried A.,Mischnick-Luebbecke, Petra,Brassat, Baerbel,Lutz, Sabine,Wenz, Gerhard
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