کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1338591 | 979672 | 2013 | 9 صفحه PDF | دانلود رایگان |

The oxidation reactions kinetics of a series of related saccharides by aqua-oxo chromium(IV) ion, (H2O)5CrIVO2+, were carried out in perchloric acid aqueous solutions. These reactions yield superoxochromium(III) ion, CrO22+, providing evidence that the two-electron reduction of CrO2+ to Cr2+ occurred in a single step. In all of these reactions, Cr2+ is the immediate product and could be trapped as CrO22+ when an excess of oxygen was present. The bimolecular rate constants for different aldoses and d-glucitol are independent of [H+] in the range 0.1–1.0 M. Relative reactivities of these saccharides toward CrO2+ reduction are 1-methyl-α-d-glucopyranose << 1-methyl-α-d-galactopyranose ∼ 3-O-methyl-d-glucopyranose ∼ 6-desoxi-l-galactopyranose ∼ 2-desoxi-d-glucopyranose ∼ d-glucopyranose << d-galactopyranose << d-glucitol. The oxidation of aldonic acid such as d-gluconic by CrO2+ showed the same mechanism but the redox process is strongly inhibited when [H+] increases. Activation parameters were also determined for selected reactions. On the basis of the kinetic result, activation parameters data and oxidized organic products, the mechanism of saccharides oxidation by CrO2+ is proposed to be a direct hydride-ion transfer.
The mechanism of saccharides oxidation by CrO2+ was proposed to be a direct hydride-ion transfer.Figure optionsDownload as PowerPoint slide
Journal: Polyhedron - Volume 49, Issue 1, 25 January 2013, Pages 84–92