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The condensation of aldehydes, beta-keto esters and urea catalyzed by NH(2)SO(3)H in ethanol results dihydropyrimidinones in high yields under ultrasound irradiation.

Claisen-Schmidt condensation of acetophenone with aromatic aldehydes catalyzed by pulverized KOH and KF-Al2O3 results chalcones in 52-97% and 83-98% yields respectively in alcoholic solvent under ultrasound irradiation.

Background

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BACKGROUND: Pollution caused by industrial wastewater has become a common problem for many countries. In particular, dye pollutions from industrial effluents disturb human health and ecological equilibrium. The discharge of highly colored synthetic dye effluents is aesthetically displeasing and can damage the receiving water body by impeding penetration of light. Azo dyes can be reduced to more hazardous intermediates on anaerobic conditions. Therefore, an effective and economic treatment of effluents containing a diversity of textile dyes has become a necessity for clean production technology for textile industries. Herein we wish to report the degradation of Acid Red 88 by the combination of Fenton's reagent and ultrasound irradiation.

A classic carbon material—expanded graphite (EG), was prepared and proposed for a new application as catalysts for activating peroxydisulfate (PDS). EG samples prepared at different expansion temperatures were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and other methods. It was observed that there existed a remarkable synergistic effect in the EG/PDS combined system to degrade Acid Red 97 (AR97). Unlike other carbon material catalysts, sp2 carbon structure may be the main active site in the catalytic reaction. The EG sample treated at 600 °C demonstrated the best catalytic activity for the activation of PDS. Degradation efficiency of AR97 increased with raising PDS dosage and EG loadings. The pH of aqueous solution played an important role in degradation and adsorption, and near-neutrality was the optimal pH in this research. It was assumed that the radical pathway played a dominant role in AR97 degradation and that oxidation of AR97 occurred in the pores and interface layer on the external surface of EG by SO4·− and ·OH, generated on or near the surface of EG. The radical oxidation mechanism was further confirmed by electron paramagnetic resonance spectroscopy. The EG sample could be regenerated by annealing, and the catalytic ability was almost fully recovered.

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