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Choice of a suitable hetero-aromatic nitrogen base as promoter for chromic acid oxidation of dl-mandelic acid in aqueous media at room temperature.
- Source :
- Research on Chemical Intermediates; Feb2013, Vol. 39 Issue 2, p631-643, 13p, 4 Diagrams, 1 Chart, 9 Graphs
- Publication Year :
- 2013
-
Abstract
- Chromic acid oxidation of dl-mandelic acid in the presence and absence of different promoters has been studied in aqueous media under the kinetic conditions [mandelic acid] ≫ [Cr(VI)] and [promoter] ≫ [Cr(VI)] at 30 °C. The promoters used in this oxidation reaction, picolinic acid (PA), 2,2′-bipyridine (bpy), and 1,10-phenanthroline (phen), are strong chelating ligands which form complexes with most transition metal ions. The reaction is first-order with regard to [H], [mandelic acid], and [Cr(VI)] and also has first-order dependence on [promoter]. HCrO was found to be kinetically active in the absence of promoters; in the presence of promoters the Cr(VI)-promoter complexes were believed to be the active oxidants. In this path the Cr(VI)-promoter complex in each case undergoes nucleophilic attack by the mandelic acid to form a ternary complex which subsequently undergoes redox decomposition involving 3 e transfer as the rate-determining step. Among the three promoters oxidation is much faster with 1,10-phenanthroline. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09226168
- Volume :
- 39
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Research on Chemical Intermediates
- Publication Type :
- Academic Journal
- Accession number :
- 84936146
- Full Text :
- https://doi.org/10.1007/s11164-012-0585-y