(13d) Self-Condensation of Acetophenone to Dypnone: Synergism of Microwave and Solid Acid Catalysts

The synthesis of dypnone, an intermediate for the production of a large range of compounds, was carried out via the self-condensation of acetophenone using microwave irradiation over various solid acid catalysts. The reactions were carried out under solvent free conditions and cesium substituted dodecatungstophosphoric acid supported on K-10 clay (designated as Cs-DTP/K-10) was found to be the best catalyst. The conversion of acetophenone and selectivity for trans-dypnone using Cs-DTP/K-10 (0.10 g/cm3) at 413 K was 56% and 92%, respectively. A positive effect of microwave irradiation on the rate of reaction was observed in comparison with conventional heating. The catalyst was recycled three times to show that there is only a marginal decrease in activity on recycled catalyst with no loss in the selectivity for dypnone under microwave irradiation. The effect of various reaction parameters on the rate of reaction was investigated to deduce the intrinsic kinetics of the reaction. Based on the experimental data, a suitable kinetic model was developed.