کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1309696 | 975218 | 2009 | 8 صفحه PDF | دانلود رایگان |

12-Tungstophosphoric acid (PW) supported on different metal oxides (SiO2, γ-Al2O3, KSF, K10) and activated carbon were prepared by impregnation method and their catalytic performances were evaluated in three component condensation of benzaldehyde, ethyl acetoacetate and ammonium acetate to afford corresponding 1,4-dihydropyridine. A high catalytic activity was found over silica supported PW. Effect of PW loading, catalyst loading and solvent was studied to introduce the best reaction condition. Based on the above experimental finding, catalytic performances was optimized with a loading of 40% PW onto SiO2 (0.2 g) under solvent-free condition. The characterization data derived from FT-IR, XRD, and TGA–DSC techniques reveal that the PW on silica support exists in Keggin structure. In addition, acidity measurements were performed by potentiometric titration with n-butylamine. The activity of the catalysts is strongly dependent on their acidic characteristic which, in turn, depended on PW loading. Finally, a series of 4-aryl, N-alkyl, and N-aryl substituted 1,4-dihydropyridines have been synthesized in high to excellent yield in short reaction times. PW/SiO2 was found to be reusable and a considerable catalytic activity still could be achieved after fourth run.
Activity of different supported 12-tungstophosphoric has been studied in the synthesis of 1,4-dihydropyridines. Characterization of the best catalyst was investigated by FTIR, XRD, TGA–DSC and BET. A series of 4-aryl, N-alkyl, and N-aryl substituted 1,4-dihydropyridines have been synthesized in high to excellent yield.Figure optionsDownload as PowerPoint slide
Journal: Inorganica Chimica Acta - Volume 362, Issue 10, 1 August 2009, Pages 3555–3562