Ultrasound enhanced reactions involving activated carbons as catalysts: synthesis of α,β-unsaturated nitriles

Abstract α,β-Unsaturated nitriles have been synthesized by sonochemical activated reactions of carbonylic compounds with malononitrile using two basic carbons (Na + – and Cs + –Norit) as catalysts. The catalysts were characterized by thermal analysis, X-ray photoelectron spectroscopy and nitrogen adsorption isotherms. Under the experimental conditions, unsaturated nitriles can be prepared with a high activity and selectivity. The role of alkaline promoters (Na + and Cs + ) in the carbon has been studied. It is evidenced that the greater the basicity and the amount of catalyst, the higher is the conversion. For comparison, the condensation reaction has also been carried out in a batch reaction system and the influence of the temperature in both (batch and ultrasonic) systems has been studied.