Secondary amine based ionic liquid and defective Keggin type heteropoly acid (HPA) are separately used for efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles assisted by microwave (MW). ...Secondary amine based ionic liquid and defective Keggin type heteropoly acid (HPA) are separately used for efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles assisted by microwave (MW). Eco-friendly solvent free procedure, short reaction time, high yield of products and reusability of catalysts are important features of the synthesis. A comparative study on the efficiency of the two catalysts is reported. This work further demonstrates the alternate use of urea, instead of often used ammonium acetate, as source of nitrogen.展开更多
The redox properties of molybdovanadoarsenic heteropolyacids having keggin structure,H x[AsV nM O 12-n O 40 ]·YH 2O(n=1~4),were studied with polarography,cyclic voltammetry and XPS.It was ascertained that three ...The redox properties of molybdovanadoarsenic heteropolyacids having keggin structure,H x[AsV nM O 12-n O 40 ]·YH 2O(n=1~4),were studied with polarography,cyclic voltammetry and XPS.It was ascertained that three redution steps for the four heteropolyacids involved 2,2,2 electrons accompanied by the adition of 1,1,1 protons.A reduction mechanism has been proposed.The oxidation ability of these heteropolyacids increases with the increase of the substitution of vanadium.展开更多
文摘Secondary amine based ionic liquid and defective Keggin type heteropoly acid (HPA) are separately used for efficient one-pot four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles assisted by microwave (MW). Eco-friendly solvent free procedure, short reaction time, high yield of products and reusability of catalysts are important features of the synthesis. A comparative study on the efficiency of the two catalysts is reported. This work further demonstrates the alternate use of urea, instead of often used ammonium acetate, as source of nitrogen.
文摘The redox properties of molybdovanadoarsenic heteropolyacids having keggin structure,H x[AsV nM O 12-n O 40 ]·YH 2O(n=1~4),were studied with polarography,cyclic voltammetry and XPS.It was ascertained that three redution steps for the four heteropolyacids involved 2,2,2 electrons accompanied by the adition of 1,1,1 protons.A reduction mechanism has been proposed.The oxidation ability of these heteropolyacids increases with the increase of the substitution of vanadium.