Tosyl starch acetate

Synthesis of /Htoluenesulfonyl (tosyl) starch, and tosyl starch acetate... 

Reaction of tosyl starch and tosyl starch acetate viith iodine... 

Standard C-NMR spectra of the tosyl starch acetates and propionates are appropriate to gain information about the distribution of the functional groups by using the carbonyl signals. In contrast to a starch triacetate which possesses three separate signals at 170.5, 170.1 and 169.2 ppm in agreement to a C=0 moiety at position 2,6 and 3, the C-NMR spectrum of tosyl starch acetate (DStos = 1-02) shows only two carbonyl peaks at 169.9 and 169.4 ppm indicating that the position 6 and 3 are acetylated. Comparable results were obtained for tosyl starch propionates. ... 

The H-NMR spectra of tosyl starch acetate respectively tosyl starch propionate are suitable to calculate the DStos values (Eq. 1) from the protons both of the methyl groups or the aromatic rings of the tosylate moieties as well as from the methyl groups of the acetyl or propionyl ester function. 

For a typical preparation, to a stirred solution of tosyl starch (1.0 g, DStos = 1.02) in 20 ml pyridine 0.3 g A iV-dimethylaminopyridine (DMAP) and 10 ml (106.0 mmol) acetic anhydride were added. The mixture was kept at 20°C for20 h and at 80 °C for 5 h. After cooling down to room temperature, the product was isolated by precipitation in 150 ml ethanol, filtered off, washed with ethanol and dried at 50 C under vacutun. 

It is well known that the nucleophilic displacement reactions at tosylated polysaccharides are limited or at least mainly directed towards the primary positions . Therefore, our interest was focused on 6-0-tosyl starch samples with DStos 1- One suitable synthesis path is the protection of 0-2 and the subsequent tosylation. A useful protecting group may be the acetyl ester function. It was recently found that in contrast to conventional esterification processes of starch with acetic anhydride, which leads to a statistic distribution of the ester groups, an acetylation of starch dissolved in DMSO with acetic acid vinyl ester in the presence of sodium chloride yields 2-0-acetyl starch of varying DSac from 0.1 to 1.0. The functionalisation patterns of these new starch products were unambiguously proved by means of various NMR measurements including two dimensional methods . 

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