کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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40726 | 45863 | 2012 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Simplified preparation of chirally modified nickel catalyst for enantioselective hydrogenation: A step forward to industrial use Simplified preparation of chirally modified nickel catalyst for enantioselective hydrogenation: A step forward to industrial use](/preview/png/40726.png)
A chirally modified nickel catalyst for the enantio-differentiating hydrogenation of β-ketoesters is conventionally prepared by immersing the pre-activated metallic nickel into an aqueous solution of enantiopure tartaric acid (so called “modification step”). During the pre-activation step, nickel precursor is commonly treated with hydrogen gas at elevated temperatures of up to 473 K. The X-ray photoelectron spectral examinations of chirally modified nickel catalysts obtained under the different modification conditions revealed that the chiral modification process itself plays a major role in activating the nickel surface whilst the pre-activation procedure is a less important factor. The corresponding enantio-differentiating hydrogenations of methyl acetoacetate in the liquid phase using the prepared chiral catalysts unambiguously confirmed this conclusion, providing quantitative conversions and high enantioselectivities of up to 90%.
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► Metallic 3-μm nickel powder catalyst modified with (R,R)-tartaric acid and NaBr.
► Modified catalyst afforded up to 90% ee in the hydrogenation of methyl acetoacetate.
► Chiral modification process activates nickel surface prior to the modification.
► Potentially hazardous pre-activation by hydrogen gas can be avoided.
Journal: Applied Catalysis A: General - Volumes 445–446, 28 November 2012, Pages 269–273