Catalysis of radical decomposition of hydroperoxides on the surface of modified montmorillonite

Abstract

4-Hydroxy-3-methyl-4′-benzeneazo(azobenzene) is used as an inhibitor to study the kinetics of radical generation upon cumyl hydroperoxide or tert-butyl hydroperoxide decomposition in microemulsions formed in the presence of cationic surfactants in organic solvents and on the surface of montmorillonite particles modified with cationic surfactants. It is demonstrated that, in contrast to microemulsions, at comparable surfactant contents, modified montmorillonite has almost no effect on the decomposition rate of hydro-peroxides. A considerable catalytic effect is only detected after Cu(2+) ions (≤0.1 wt %) are additionally applied onto the surface of its nanoparticles. The addition of polar solvents dramatically decelerates the decomposition of hydroperoxides. The activation energies of the reaction are determined for the dispersions of modified montmorillonite in toluene (56 kJ/mol) and toluene-ethanol mixture (69 kJ/mol).