Reaction of Benzene with Cu(II)- and Fe(III)-Exchanged Hectorites

M. P. Eastman, D. E. Patterson and K. H. Pannell
Department of Chemistry, University of Texas at El Paso, El Paso, Texas 79968

Abstract: The reaction of benzene with exchangeable Cu(II) and Fe(III) in hectorite clay films was studied by electron paramagnetic resonance (EPR). The reaction when carried out in a sealed tube between 60° and 100°C produced a variety of organic radical products. The nature of these products depended on the concentration of water in the reaction medium and the reaction time. The free radicals were accompanied by a reduction in the oxidation state of the metal ions; this process had a zero-order dependence on the metal ion concentration. The activation energies determined from the zero-order rate constants are 67 ± 11 kJ/mole (Cu(II)) and 46 ± 6 kJ/mole (Fe(III)). The free radicals initially formed under anhydrous conditions appeared to populate sites in the interlayer region; the activation energies determined for this first order process are 57 ± 9 kJ/mole (Cu(II)) and 42 ± 3 kJ/mole (Fe(III)). These activation energies are within experimental error of those determined from the metal ion kinetics. The EPR signal due to organic radicals showed little temperature dependence; thus, exchange processes involving organic free radicals were probably not important in determining EPR lineshapes.

Key Words: Adsorption • Benzene • Copper • Electron paramagnetic resonance • Free radical • Hectorite • Iron

Clays and Clay Minerals; August 1984 v. 32; no. 4; p. 327-333; DOI: 10.1346/CCMN.1984.0320411
© 1984, The Clay Minerals Society
Clay Minerals Society (www.clays.org)