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Minami-rinkan, Japan

Osawa T.,University of Toyama | Kizawa T.,Metek Kitamura Co. | Ikeda S.,Metek Kitamura Co. | Kitamura T.,Metek Kitamura Co. | And 3 more authors.
Chemistry Letters | Year: 2013

The performance of a catalytic system consisting of metallic Ni powder, tartaric acid (TA), and NaBr in the enantioselective hydrogenation of methyl acetoacetate was strongly influenced by the pH of TA solution upon chiral modification, which is attributable to the pH-induced change in the surface composition of Ni catalyst as unambiguously confirmed by X-ray photoelectron spectroscopy for the first time. © 2013 The Chemical Society of Japan. Source


Osawa T.,University of Toyama | Lee I.-Y.S.,University of Toyama | Ikeda S.,Metek Kitamura Co. | Kitamura T.,Metek Kitamura Co. | And 3 more authors.
Applied Catalysis A: General | Year: 2012

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%. © 2012 Elsevier B.V. Source


Osawa T.,University of Toyama | Kizawa T.,University of Toyama | Lee I.-Y.S.,University of Toyama | Ikeda S.,Metek Kitamura Co. | And 4 more authors.
Catalysis Communications | Year: 2011

Metallic Ni catalysts co-modified with (R,R)-tartaric acid and NaBr showed high enantioselectivity and durability upon hydrogenation of methyl acetoacetate to give methyl 3-hydroxybutyrate. The chirally modified catalyst prepared from 3-μm Ni powder was highly robust to maintain the hydrogenation activity and enantiodifferentiating ability for ca. 3 months under dry condition, which enables long-term storage and hence facilitates commercial distribution and industrial application. © 2011 Elsevier B.V. All rights reserved. Source

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