Cross-dimerization of α-methylstyrene with isoamylene and aldol condensation of cyclohexanone using a cation-exchange resin and acid-treated clay catalysts

Abstract

The utility of cation-exchange resin and acid-treated clay catalysts was investigated for two non-aqueous reaction systems, viz. the cross-dimerization of a-methylstyrene with isoamylene and the aldol condensation of cyclohexanone. A systematic investigation of the cross-dimerization of α-methylstyrene with isoamylene was carried out in the temperature range 40-100°C employing different reactant molar ratios. The effect of these parameters on the selectivity for cross-dimerization as compared to the dimerization of the individual reactants was studied. In the liquid-phase aldol condensation of cyclohexanone, special emphasis was laid on the selectivity for 2-(1-cyclohexen-1-yl)cyclohexanone, an intermediate in the manufacture of o-phenylphenol. The effect of the temperature was studied in the range 100-160°C. The efficacy of the acid-treated clay over cation-exchangers has been highlighted. The experimental data were analysed and correlated by heterogeneous models. The cross-dimerization reaction was found to follow Rideal-Eley kinetics, while the condensation reaction conformed to the Langmuir-Hinshelwood mechanism.