Kinetics and mechanism of the oxidation of D-galactono-1,4-lactone by CrVI and CrV
| Autor: | Mabel Santoro, Juan M. Salas-Peregrín, Claudia Palopoli, M. Quiroz, C. Brondino, Sandra Signorella, Luis F. Sala |
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| Rok vydání: | 1998 |
| Předmět: |
chemistry.chemical_classification
Inorganic chemistry Kinetics chemistry.chemical_element Substrate (chemistry) Lyxonic acid Medicinal chemistry Redox law.invention Inorganic Chemistry Chromium chemistry law Materials Chemistry Physical and Theoretical Chemistry Linkage isomerism Electron paramagnetic resonance Lactone |
| Zdroj: | Scopus-Elsevier |
| ISSN: | 0277-5387 |
| DOI: | 10.1016/s0277-5387(98)00062-x |
| Popis: | The oxidation of d -galactono-1,4-lactone by CrVI yields d -lyxonic acid, carbon dioxide and Cr3+ as final products when an excess of sugar acid over CrVI is used. The redox reaction occurs through CrVI → CrIII and CrVI → CrV → CrIII paths. The complete rate law for the CrVI oxidation reaction is expressed by −d [CrVI] \dt = (k0+kH [H+] ) [gal] [CrVI] , where k0 = (31±3) ×10−4 M−1 s−1 and kH = (99±5) ×10−4 M−2 s−1, at 40°C. CrV is formed in a rapid step by reaction of the CO·− 2 radical with CrVI. CrV reacts with the substrate faster than does CrVI. The CrV oxidation follows the rate law : −d [CrV] \dt = ( k ′ 0 +k ′ H [H+] ) [gal] , where k ′ 0 = (15±2) ×10−3 M−1 s−1 and k ′ H = (34±4) ×10−3 M−2 s−1, at 40°C. The EPR spectra show that several intermediate [Cr (O) (gala) 2] − linkage isomers are formed in rapid pre-equilibria before the redox steps. |
| Databáze: | OpenAIRE |
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