The Oxidation of Phenol by Ferrate(VI) Andferrate(V). A Pulse Radiolysis and Stopped-Flow Study

Abstract

Potassium ferrate. K₂FeO₄, is found to oxidize phenol in aqueous solution (5.5 ± pH ± 10) by a process which is second order in both reactants; -d[Fe^vt]/dt=ki[Fe^VI][phenol], kI = 10⁷M⁻¹s⁻¹. Product analysis by HPLC showed a mixture of hydroxylated products, principally paraquinone. and biphenols that indicate that oxidation of phenol occurs by both one-electron and two-electron pathways. The two-electron oxidant. producing both para- and ortho-hydroxylated phenols is considered to be ferrate(V) which is itself produced by the initial one-electron reduction of ferrate(VI). The rate of ferrate(V) reaction with phenol was determined by pre-mix stopped flow pulse-radiolysis and found to be k7 = (3.8 ± 0.4)± 10⁵M⁻¹s⁻¹.

Key Words:

• Ferrate(VI)
• Ferrate(V)
• Phenol
• Phenoxyl Radical
• Pulse Radiolysis.