Dextran, acetate structure

Preliminary examinations of dextran structures were conducted by optical rotation, infrared spectroscopy and periodate-oxidation reactions. More detailed results can be achieved by methylation analysis [19]. The hydroxyl groups are methylated with methyl iodide after activation with sodium methylsulfinyl carbanion (Fig. 2). The methyl dextran is hydrolysed to the corresponding different methylated monosaccharides, which are furthermore reduced and peracetylated. The resulting alditol acetates of methylated sugars are separated by gas chromatography and identified by their retention times. In particular, a combined capillary gas-liquid chromatography/mass... 

Subsequent conversion of dextran derivatives with acetic acid or propionic acid anhydride is an effective method for revealing structural features on the molecular level. This is illustrated on a dextran propionate (Mw 5430 gmol x) which can be completely acetylated with acetic anhydride/pyridine in a separate step yielding a peracetylated sample (dextran propionate acetate, DPA). The assignment of the chemical shifts of DPA is carried out via 2D NMR (Fig. 17). 

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