Mechanistic study of the oxidation of N-phenyldiethanolamine by bis(hydrogen periodato)argentate(III) complex anion

Abstract

The kinetics of oxidation of phenyldiethanolamine (PEA) by a silver(III) complex anion, [Ag(HIO 6 ) 2 ] 5) , has been studied in an aqueous alkaline medium by conventional spectrophotometry. The main oxidation product of PEA has been identified as formaldehyde. In the temperature range 20.0-40.0°C , through analyzing influences of [OH ) ] and [IO 4 ) ] tot on the reaction, it is pseudo-first-order in Ag(III) disappearance with a rate expression:where k 1 = (0.61 ± 0.02) Â 10 )2 s )1 , k 2 = (0.049 ± 0.002) M )1 s )1 at 25.0°C and ionic strength of 0.30 M. Activation parameters associated with k 1 and k 2 have also been derived. A reaction mechanism is proposed involving two preequilibria, leading to formation of an Ag(III)-periodato-PEA ternary complex. The ternary complex undergoes a two-electron transfer from the coordination PEA to the metal center via two parallel pathways: one pathway is spontaneous and the other is assisted by a hydroxide ion.

Oxidation of 3-(4-methoxyphenoxy)-1,2-propanediol by bis(hydrogen periodato)argentate(III) complex anion: a kinetic study

“…These characteristics interest us to study the reactions of these compounds. This paper is in continuation of our work on elucidation of reaction mechanisms for the oxidations of functionally and biologically important molecules by bis(hydrogen periodato)argentate(III) complex anion ([Ag(HIO 6 ) 2 ] 5-) [6][7][8]. This Ag(III) complex has a typical square-planar geometry around the metal center [9][10][11][12] and is moderately stable in aqueous alkaline medium.…”