Kinetics and mechanism of oxidation of ethylenediamine and related compounds by diperiodatoargentate (III) ion

✍ Scribed by Anil Kumar; Vaishali; P. Ramamurthy

• Publisher: John Wiley and Sons
• Year: 2000
• Tongue: English
• Weight: 167 KB
• Volume: 32
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/(sici)1097-4601(2000)32:5<286::aid-kin4>3.0.co;2-e

✦ Synopsis

The oxidation of ethylenediamine by diperiodatoargentate (III) ion has been studied by stopped-flow spectrophotometry. Kinetics of this reaction involves two steps. The first step is the complexation of silver (III) with the substrate and is over in about 10 ms. This is followed by a redox reaction in the second step that occurs intramolecularly from the substrate to the silver (III) center. The rate of reduction of silver (III) species by ethylenediamine, ethanolamine, and 1,2-ethanediol were observed to be 1.2 ϫ 10 4 , 1.1 ϫ 10 2 , and 0.14 dm 3 mol Ϫ1 s Ϫ1 , respectively, at 20ЊC. The reaction rate shows an inverse dependence on [IO 4 Ϫ ] and [OH Ϫ ] in the low concentration range (Յ1 ϫ 10 -3 mol dm Ϫ3 ). At higher [OH Ϫ ] (Ͼ1 ϫ 10 Ϫ3 mol dm Ϫ3 ) the rate of reaction starts increasing and attains a limiting value at very high [OH Ϫ ]. The rate of deamination of ethylenediamine is enhanced by its complexation with silver (III). The involvement of [Ag III (H 2 IO 6 ) (H 2 O) 2 ] and [Ag III (H 2 IO 6 ) (OH) 2 ] 2Ϫ are suggested as the reactive silver (III) species kinetically in mild basic and basic conditions, respectively.