Mechanistic Investigation of Uncatalyzed and Osmium(VIII) Catalyzed Oxidation of Guanidine by Ag(III) Periodate Complex in Aqueous Alkaline Medium: A Comparative Kinetic Approach

• Published in: Industrial & engineering chemistry research Vol. 48; no. 16; pp. 7550 - 7560
• Main Authors: Abbar, Jyothi C, Lamani, Shekappa D, Nandibewoor, Sharanappa T
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19-08-2009
• Subjects: Applied sciences; Catalysis; Catalytic reactions; Chemical engineering; Chemistry; Exact sciences and technology; General and physical chemistry; Kinetics, Catalysis, and Reaction Engineering; Reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Catalytic reaction; Oxidation; Kinetics
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie900691z

The oxidation of guanidine hydrochloride (GH) by diperiodatoargentate(III) (DPA) has been investigated both in the absence and presence of [Os(VIII)] catalyst in alkaline medium at a constant ionic strength of 0.10 mol dm−3 spectrophotometrically. The oxidation products were identified by spectral studies. The stiochiometry was same in both the cases, i.e., [GH]/[DPA] = 1:1. In both the catalyzed and uncatalyzed cases, the order of the reaction with respect to [DPA] was unity while the order with respect to [GH] was <1 over the concentration range studied. The rate increased with an increase in [OH−] and decreased with an increase in [IO4 −]. The order with respect to [Os(VIII)] was unity. Suitable mechanisms were proposed. The reaction constants involved in the different steps of the reaction mechanisms were calculated for both reactions. Kinetic experiments suggest that [Ag(H2IO6)(H2O)2] is the reactive silver(III) species and [OsO4(OH)2]2− is the reactive Os(VIII) species.