Kinetics and mechanism of electron transfer from phenolate anion to hexacyanoferrate (III) in aqueous alkaline media

✍ Scribed by Pradeepta K. Panda; Rama Krushna Panda; P. S. Radhakrishna Murti

• Publisher: John Wiley and Sons
• Year: 1987
• Tongue: English
• Weight: 677 KB
• Volume: 19
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550190207

✦ Synopsis

A kinetic reinvestigation of the title redox system in aqueous alkaline media at 35°C and a n ionic strength of 0.5 mol dm-3 shows that the reaction follows a pseudosecondorder Fe(CN)i ~ disappearance. While varying LphenolIo and [OH 1 exhibit a linear influence on the pseudo-second-order rate constant, varying [FetCN); lo and [Fe(CN);~ lo, initially taken, have a complicated inhibitory effect on the same. The major phenoloxidation products isolated under a chosen condition are 2,2'-and 4,4'-dihydroxydiphenyl. Results are interpreted in terms of a probable mechanism which envisages a reversible formation, by the first one-electron transfer, of a reactive phenoxy radical (PhO') which on the second one-electron transfer forms a less reactive ion-pair intermediate (stabilized by the Fe(CN)i-produced) to decompose rate-determiningly to phenoxonium cation (PhO-) and Fe(CN):-, the product-formation steps being very rapid and kinetically indistinguishable. *Non-SI units employed in the text: M = mol dm '.