Synthesis of new organophosphonates via domino Knoevenagel-Phospha-Michael reaction catalyzed by modified multi-walled carbon nanotube
Subject Areas : Journal of Nano Chemistry and Electrochemistry
1 - Department of Chemistry, Marvdasht Branch, Islamic Azad University, Marvdasht, Iran
Keywords: "domino Knoevenagel-Phospha-Michael reaction", "modified multi-walled carbon nanotube", "organophosphonates, " "dimedone", "triethylphosphite",
Abstract :
A green synthesis of new organophosphonates via domino Knoevenagel-Phospha-Michael reaction has been reported. Multi-walled carbon nanotube-CO-NH(CH2)2NH-SO3H was prepared through a three-step functionalization of commercial multi-walled carbon nanotubes and has been used as acidic heterogeneous catalyst. In brief it was prepared by dissolving Multi-walled carbon nanotube-CO-NH(CH2)2NH2 in n-hexane. The flask was immediately equipped with a mechanical stirrer, a dropping funnel and an ice bath. chloro sulfonic acid (diluted by n-hexane) was added to dropping funnel and poured into the flask for 12 h. Finally, the reaction mixture was stirred for 24 h at room temperature. The appropriate product was produced through the distillation of solvent and then dried under vacuum at 80 °C for 8 h. At first, Knoevenagel condensation are performed between aromatic aldehyde and dimedone and then corresponding α,β-unsaturated carbonyl compound is reacted with triethylphosphite. The use of ethanol as a green solvent, easy work-up, mild reaction conditions are the main advantages of this work. This synthesis was accomplished in heterogeneous conditions and Nano catalyst recovered after the finishing of the reaction. The catalyst can use several times without losing catalytic activity. The structures of products were determined by 1H NMR, 13C NMR and 31P-NMR and elemental analysis.
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