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Details van artikel 103 van 252 gevonden artikelen
| Titel: |
Mechanistic Investigations of Oxidation of Amino Sugars by Sodium N-Chloro-P-Toluenesulfonamide in Alkaline Medium |
| Auteur: |
Raghavendra, M. P. Mahadevappa, D. S. Rai, K. M. L. Rangappa, K. S. |
| Verschenen in: |
Journal of carbohydrate chemistry |
| Paginering: | Jaargang 16 (1997) nr. 3 pagina's 343-358 |
| Jaar: |
1997-03-01 |
| Inhoud: |
The kinetics of oxidation of D-glucosamine and D-galactosamine (S) to the respective aldonic acids by sodium N-chloro-p-toluenesulfonamide or chloramine-T (CAT) in the presence of alkali at 40 °C follows the rate law, -d [CAT] / dt = k [CAT] [S] [HO-]x, where x <1. The products, p-toluenesulfonamide and Cl- ions had no influence on rate. Increase of ionic strength increased the rate and the Debye-Huckel plot had a slope of 0.6. The rate decreased when the dielectric constant of medium was decreased and values of dAB, the size of activated complex, were calculated by using the Scatchard equation. The rate increased in D2O solution and the inverse solvent isotope effect k(D2O) / k(H2O) was 1.94 and 1.53, respectively, for the two amines. Proton inventory was studied in H2O-D2O mixtures. Composite activation parameters for the reaction were determined from Arrhenius plots. The mechanism assumes the formation of sugar alkoxy anion, a rate limiting complexation with oxidant, formation of the respective pentose through decarboxylation and deamination, and further oxidation to D-arabonic and D-lyxonic acids, respectively. The thermodynamic parameters for sugar-alkoxy anion formation and activation parameters for the rate limiting step were evaluated from double reciprocal plots of 1/kobsvs.1/ [HO-]. |
| Uitgever: |
Taylor & Francis |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
Details van artikel 103 van 252 gevonden artikelen
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