کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
65839 | 48405 | 2013 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Improved method for immobilization of a chiral complex on PTA/alumina for asymmetric hydrogenation of a β-ketoester Improved method for immobilization of a chiral complex on PTA/alumina for asymmetric hydrogenation of a β-ketoester](/preview/png/65839.png)
• Immobilization method was modified with acid in preparation of Ru-BINAP/PTA/Al2O3.
• In hydrogenation of β-ketoesters the modified catalyst had better performances.
• Acid sites were formed by HPA with Keggin structure on the modified catalyst.
• The acid sites might provide additional active sites for the reaction.
Ru-BINAP was immobilized on alumina using the well-known Augustine method with heteropoly acid (HPA) as the anchoring agent (“Augustine catalyst”). The supported catalyst was tested in a high-pressure reaction such as asymmetric hydrogenation of methyl acetoacetate (MAA). Since the activity of the supported catalyst was significantly lower than that of the homogeneous catalyst, the solvent used in preparing PTA/Al2O3 was changed from ethanol to a solution of HCl. The modified supported catalyst (“modified Augustine catalyst”) exhibited higher conversion, better selectivity, and improved enantioselectivity compared with the catalyst prepared by the Augustine method. The modified Augustine catalyst also produced β-hydroxyesters with good yield and enantioselectivity in asymmetric hydrogenation of various β-ketoester derivatives. The modified Augustine catalyst was examined by FT-IR, XRD, NH3-TPD, and ICP-AES, which revealed the existence of strong acid sites formed by HPA with a Keggin structure. These results were attributed to the effect of enhanced acidity on the modified Augustine catalyst.
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Journal: Journal of Molecular Catalysis A: Chemical - Volume 373, July 2013, Pages 55–60