Electrochemical Reactions of Some Organic Free Radicals at Colloidal Silver in Aqueous Solution

Article abstract of DOI:10.1021/j100462a031

Electron-transfer processes between simple 1-hydroxyalkyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals and metal ions at the surface of colloidal silver are described.C6H6OH radicals are oxidized by Ag(1+) to yield phenol.In the absence of Ag(1+), no electron exchange between C6H6OH and the silver particles takes place.When the silver particles carry a tiny deposit of thallium metal, the C6H6OH radicals are reduced.Cu(1+) (and Cu(2+)) ions adsorbed on the silver particles oxidize C6H6OH radicals.However, reduction of C6H6OH by Cu(1+) occurs, if the silver particles are covered with copper metal. 1-Hydroxyalkyl and 2-ethoxyethyl radicals reduce Tl(1+) ions in the presence of colloidal silver, but oxidize Tl atoms in homogeneous solution.Water can be decomposed to yield H2 by 1-hydroxy-1-methyl and 1-hydroxyethyl, but not by 1-hydroxymethyl, 1-ethoxyethyl, and 2-hydroxycyclohexadienyl radicals.These findings are dicussed in terms of standard potentials for the oxidation and reduction of the radicals and in terms of distribution of occupied and unoccupied electronic redox leves in the radicals and the colloidal metal.In these experiments γ radiolysis was used to produce the radicals at a controlled rate.