Hydrogenation Of Methyl Acetoacetate Research Articles

Study of the parameters controlling the enantio-differentiating ability of asymmetrically modified solid catalysts for the hydrogenation of γ-ketoesters

The enantio-differentiating hydrogenation of γ-ketoesters was carried out over asymmetrically modified solid catalysts. The parameters affecting the enantiomer excess (ee) were investigated and the results were compared with those of the hydrogenation of methyl acetoacetate and 2-octanone reported in the literature. The highest value of enantiomer excess of 51% was attained for the hydrogenation of methyl 4-oxopentanoate over a tartaric acid (TA)-NaBr-modified reduced nickel catalyst prepared from nickel oxide. The amount of NaBr in the modification solution needed to be optimized according to the manufacturers of the nickel oxides. The addition of an appropriate amount of carboxylic acid to the reaction media increased the enantiomer excess of the hydrogenated products.

The kinetics of enantioselective hydrogenation of methyl acetoacetate using a modified Raney nickel catalyst

The kinetics of enantioselective hydrogenation of methyl acetoacetate using Raney nickel modified by (2R,3R)-(+)-tartaric acid were studied, thereby focusing on the effects of the reaction conditions on the enantioselectivity. Reactions were carried out in a liquid phase under atmospheric and increased hydrogen pressure. The reaction course was described by the exponential kinetics model and by Langmuir-Hinshelwood kinetics assuming the existence of two types of active sites on the catalyst surface, selective and non-selective. Using Langmuir-Hinshelwood kinetics, the acquired parameters were used for discussion of the effects of the reaction conditions on the enantioselectivity and the mechanism of the enantioselective hydrogenation.

Enantio-differentiating hydrogenation of methyl acetoacetate over fine nickel powder with in situ modification

Enantio-differentiating hydrogenation of methyl acetoacetate (MAA) was carried out using fine nickel powder (FNiP) by adding tartaric acid (TA) and sodium salts to the reaction media (in situ modification) instead of using a conventionally modified nickel catalyst. This catalyst prepared by the in situ modification gave an optical yield up to 79%.

First heterogenisation of Rh–MeDuPHOS by occlusion in PDMS (polydimethylsiloxane) membranes

The first heterogeneous system of Rh–MeDuPHOS, obtained by occlusion of the complex in a PDMS membrane, is reported and tested in the hydrogenation of methylacetoacetate (MAA).

ChemInform Abstract: Enantio‐Differentiating Hydrogenation of Methyl Acetoacetate over Asymmetrically Modified Supported Nickel Catalyst Prepared from Nickel Acetylacetonate.

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Influence of the starting NiAl phases on the enantio-differentiating properties of tartaric acid-modified Raney nickel

Using well-defined pure phases: Al 3Ni 2, Al 3Ni and the Al/Al 3Ni eutectic we prepared tartaric acid-modified Raney nickel (RNi 3-2, RNi 3-1, RNiE). Their catalytic properties were investigated, in the hydrogenation of methyl acetoacetate at constant hydrogen pressure (1.1 MPa) and temperature (333 K) in ethyl acetate. The enantiomeric excess went from 16% on RNi 3-2 to 25% on RNi 3-1 and up to 45% on RNiE which has been prepared using an aluminium in a high state of purity. In the presence of sodium bromide in the modifying solution, RNiE remains the best catalyst: with an ee of 80%.

The liquid-phase hydrogenation of methylacetoacetate using nickel-exchanged Y zeolite catalysts: Part I. Structure sensitivity

The liquid-phase hydrogenation of methylacetoacetate (MAA) over NiNaY and NiKY zeolites to a racemic methyl 3-hydroxybutyrate (MHB) product has been studied in a stirred reactor under a constant hydrogen purge. The variation of MHB formation with time was monitored and reaction rates accurate to ±2% are reported. The effects of variations in the supported nickel metal particle sizes (in the range 16–75 nm) on the hydrogenation activity were examined by altering either the degree of nickel exchange or the temperature of reduction. It is shown that the hydrogenation of MAA at 343 K is structure-sensitive and a correlation between reaction sensitivity and particle size is presented. Data on the reaction over Ni/Si0 2 catalysts are also provided for comparison purposes. Both the zeolite and silica-based catalysts were reusable and could be stored in the reaction solvent for extended periods of time without an appreciable loss of activity.

酒石酸修飾Ｒａｎｅｙニッケル／ＣｄＳ光触媒を用いた不斉合成 アセト酢酸メチルから３‐ヒドロキシ酪酸メチルへの不斉水素化

酒石酸修飾Ｒａｎｅｙニッケル／ＣｄＳ光触媒を用いた不斉合成 アセト酢酸メチルから３‐ヒドロキシ酪酸メチルへの不斉水素化

ChemInform Abstract: HIGHLY SELECTIVE ASYMMETRIC HYDROGENATION OF METHYL ACETOACETATE WITH NICKEL‐PALLADIUM‐KIESELGUHR CATALYST MODIFIED WITH TARTARIC ACID

AbstractUm zu einem hoch asymmetrischen Katalysator zu gelangen, ist eine 6‐9‐stündige lmmersion des Katalysators auf einem heißen Wasserbad notwendig.

酒石酸修飾ニッケル‐パラジウム‐けいそう土触媒によるアセト酢酸メチルの不斉水素化における添加物の効果

Effects of additives on the asymmetric yield of methyl 3-hydroxybutyrate were examined in the hydrogenation of methyl acetoacetate using Ni-Pd-Kieselguhr catalyst modified with tartaric acid. Addition of unsaturated compounds such as dehydroacetic acid and diethyl maleate showed almost no effect on the asymmetric yield. Only when carboxylic acids having pKa values higher than that of tartaric acid such as formic acid, acetic acid, benzoic acid, and succinic acid were used as additives, great increase in asymmetric yield was observed.

酒石酸修飾ニッケル‐パラジウム‐けいそう土触媒によるアセト酢酸メチルの高選択的不斉水素化

Effects of immersion time of the catalyst in tartaric acid solution for modification on the asymmetric activity of the modified catalyst were investigated in the hydrogenation of methyl acetoacetate. It was found that, in order to prepare highly asymmetrically active catalyst, the immersion of the catalyst for 69 hours on a hot water bath was necessary. Thus, when the catalyst immersed for 6 hours was used, the greatest asymmetric selectivity (optical yield=99%) was obtained in the hydrogenation in tetrahydrofuran and a small amount of formic acid.

The Asymmetric (Enantioface Differentiating) Hydrogenation of the C=O Double Bond with Modified Raney Nickel. XXIX.

Abstract In the asymmetric (enantioface differentiating) hydrogenation of methyl acetoacetate with modified Raney nickel catalysts, the effects of the modifying pH on the amounts of the modifying reagents adsorbed and the enantioface differentiating abilities of the catalysts were studied using glycolic acid, mandelic acid, and 2-hydroxy-3-phenylpropionic acid as the modifying reagents. The results indicate that the modifying pH governs the adsorption mode of the modifying reagent. Thus, the change in the adsorption mode of the modifying reagent with the change in the modifying pH results in changes in the amount of the modifying reagent adsorbed and in the enantioface differentiating ability of the catalyst.

Asymmetric Hydrogenation of C=O Double Bond with Modified Raney Nickel. XXIV. The Effect of Unsaturated Compounds on the Asymmetric Activity of the Catalyst

Abstract Dehydroacetic acid and methyl cis-3-acetoxycrotonate were picked out as trace impurities of the substrate, methyl acetoacetate. The effects of dehydroacetic acid, methyl cis-3-acetoxycrotonate, and diketene, which is the starting material for the preparation of methyl acetoacetate, on the asymmetric activities of catalysts modified with l-amino acids were examined in the hydrogenation of methyl acetoacetate. The above three compounds, when added to the hydrogenation system, raised the asymmetric activity of the catalyst. Also, simple unsaturated compounds, such as acetone and diethyl maleate, has a similar effect on the catalyst. The effects of the above unsaturated compounds on the asymmetric activities of the catalysts modified with l-amino acids were discussed, and it was suggested that the unsaturated compounds adsorb on the catalyst surface and might scavenge the asymmetrically uncontrolled active hydrogen absorbed on the catalyst surface.

Asymmetric Hydrogenation with Modified Raney Nickel. II. Studies on Modified Hydrogenation Catalyst. III

Abstract 1) The asymmetric R-Ni catalysts were prepared by the treatment of R-Ni with various asymmetric compounds, and the asymmetric activity of a catalyst was measured by the hydrogenation of methyl acetoacetate 2) Optical rotatory direction and power of the reduced product was affected both by the configuration and molecular size of amino acid which was used as modifying reagent. 3) The asymmetric activity of catalysts treated with N-substituted amino acids, N-acyl, N-dimethyl and N-cyanoethyl derivatives of Glu and Asp, were much less than the activity of the catalyst treated with the corresponding amino acids. 4) The asymmetric activity of the catalyst treated with d-tartaric acid and l-malic acid was tested at various conditions. The asymmetric yield in the hydrogenation of methyl acetoacetate in the presence of the catalyst treated with d-tartaric acid solution of pH 5.1∼5.2 at 100°C was about 45 percent.