Influence of basic properties of Mg,Al-mixed oxides on their catalytic activity in knoevenagel condensation between benzaldehyde and phenylsulfonylacetonitrile

The catalytic performance of Mg,Al-mixed oxides (MO20, MO25 and MO33) derived from hydrotalcites was evaluated in the Knoevenagel reaction between benzaldehyde and phenylsulfonylacetonitrile at 373 and 383 K. The best results were obtained for the sample MO20 that presented the highest basic sites density and external area and the smallest crystallite sizes. The relative amount of basic sites with weak to intermediate strength also played an important role on catalytic performance. By increasing the catalyst content from 1 to 5 wt.% at 383 K, a complete conversion of the reactants is attained, producing α-phenylsulfonylcinnamonitrile with a selectivity of 100%