Kinetics and mechanism of oxidation of nitrilotriacetic acid by diperiodatoargentate(III)

✍ Scribed by Anil Kumar; Paresh Kumar

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 80 KB
• Volume: 12
• Category: Article
• ISSN: 0894-3230
• DOI: 10.1002/(sici)1099-1395(199902)12:2<79::aid-poc86>3.0.co;2-j

✦ Synopsis

Diperiodatoargentate(III) oxidizes nitrilotriacetic acid in a mildly basic medium to produce formaldehyde and ammonia. This reaction follows a complex kinetic behaviour. The axial binding of NTA to silver(III) complex takes place on the millisecond time-scale with a second-order rate constant of (4.8 AE 0.5) Â 10 3 dm 3 mol À1 s À1 . Two electrons are transferred from bound NTA to the silver(III) centre sequentially. At low [NTA] (`1 Â 10 À3 mol dm À3 ), the rate law follows first-order kinetics with respect to NTA but at high [NTA] it becomes independent of its concentration. The first electron is transferred to the silver(III) centre with a second-order rate constant of (7.2 AE 0.5) dm 3 mol À1 s À1 . The second electron is transferred subsequently in the fast step from NTA radical to the silver(II) species. The latter stages of reaction consists of a composite process involving the oxidation of NTA and its products in parallel reactions. Kinetic experiments suggest that [Ag III (H 3 IO 6 )(H 2 O) 2 ] is the reactive silver(III) species involved.