Ultrasound-Promoted Knoevenagel Condensation Catalyzed by KF-Clinoptilolite

Potassium fluoride-clinoptilolite, which is prepared from commercially available and cheap starting materials, was used as an efficient and recyclable catalyst for Knoevenagel condensation of aromatic aldehydes with active methylene compounds under ultrasound irradiation. Short reaction times, high yields of products, ease of recovery and catalyst reusability make this new method economic and efficient.