Über Mischoxalat‐Kontakte

Langenbeck, Wolfgang; Dreyer, H.; Nehring, Dietwart; Welker, Jürgen

doi:10.1002/zaac.19552810109

Cited by 23 publications

(3 citation statements)

References 7 publications

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“…For example, the Ni-Mg-C204 catalyzed hydrogenation of ethyl cinnamate, ethyl butynoate, gaseous benzene, and cyclohexene. Likewise, the catalytic activity of other mixed catalysts, Co-Mg-C204 and Ni-Zn~C204, is explained as due to true mixed-crystal formation (249). While simple oxalates are generally prepared by precipitation reactions, at least in the case of NiC204-2H20, it has been shown that the rate-determining species for nucleation and growth is Ni(C204)22~ (11,12).…”

Section: B Industrial Applicationsmentioning

confidence: 99%

The Chemistry of the Metal Oxalato Complexes.

Krishnamurty¹,

Harris²

1961

Chem. Rev.

182

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Section: B Industrial Applicationsmentioning

confidence: 99%

The Chemistry of the Metal Oxalato Complexes.

Krishnamurty¹,

Harris²

1961

Chem. Rev.

182

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“…The thermodynamic instability of the products is emphasized in the case of unsaturated aldehydes, which are also prone to acetal and hemiacetal formation with the alcohol nucleophiles in the presence of basic or acidic activation of the reaction partners. Not surprisingly, only a few studies on conjugate additions of oxygen nucleophiles to unsaturated aldehydes, [7] and virtually no examples of enantioselective catalysis, were published at the time of the inception of our study. The products of these additions can be viewed as (protected) aldol products Abstract: The formation of 3-unsubstituted 2-isoxazolines by means of condensation reactions between a,b-unsaturated aldehydes and oximes proceeds readily in the presence of catalytic amounts of anilinium salts.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of 2‐Isoxazolines: Enantioselective and Racemic Methods Based on Conjugate Additions of Oximes

Pohjakallio

Pihko

Laitinen

2010

Chemistry A European J

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The formation of 3-unsubstituted 2-isoxazolines by means of condensation reactions between α,β-unsaturated aldehydes and oximes proceeds readily in the presence of catalytic amounts of anilinium salts. Mechanistically, the process involves a fast conjugate addition of the oxime and a slower intramolecular oxime-transfer reaction. The rate of oxime transfer was found to correlate with the acidity of the catalyst. This finding enabled us to discover an enantioselective process in which the fragile conjugate-addition product generated in the first stage is rapidly cyclized into the stable isoxazoline under acidic conditions, with conservation of enantiomeric excess. In summary, herein we describe synthetically useful protocols for accessing 3-unsubstituted 2-isoxazolines in both the enantioselective and racemic manner. The mechanism of the condensation reaction catalyzed by the anilinium salt was also investigated by NMR spectroscopy experiments in which the effect of differently substituted aldehydes and oximes as well as water on the reaction rate was studied. The results point to the rate-limiting elimination of water from the 3-hydroxy-2-isoxazolidine intermediate.

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“…Similar enhancement of catalytic performance was observed for oxide-supported metal catalysts in methanol synthesis, 15 in the hydrogenation of ethene and CO, 16,17 as well as in the selective hydrogenation of cyclohexane, cyclopropane and propene. 18,19 The contact between a metal layer and a semiconductor surface can be described by the Schottky model that assumes a charge separation at the metal-semiconductor interface and a band bending at the interface in the semiconductor. 20 Doping of the semiconductor causes a charge accumulation or depletion of charge in the metal.…”

Section: Introductionmentioning

confidence: 99%

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

Wyrzgol

Schäfer

Lee

et al. 2010

Phys. Chem. Chem. Phys.

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The preparation, characterization and catalytic reactivity of a GaN supported Pt catalyst in the hydrogenation of ethene are presented in this feature article, highlighting the use of in situ characterization of the material properties during sample handling and catalysis by combining temperature programmed reaction with in situ grazing incidence small-angle X-ray scattering and X-ray absorption spectroscopy. The catalysts are found to be sintering resistant at elevated temperatures as well as during reduction and hydrogenation reactions. In contrast to Pt particles of approximately 7 nm diameter, smaller particles of 1.8 nm in size are found to dynamically adapt their shape and oxidation state to the changes in the reaction environment. These smaller Pt particles also showed an initial deactivation in ethene hydrogenation, which is paralleled by the change in the particle shape. The subtle temperature-dependent X-ray absorbance of the 1.8 nm sized Pt particles indicates that subtle variations in the electronic structure induced by the state of reduction by electron tunnelling over the Schottky barrier between the Pt particles and the GaN support can be monitored.

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Über Mischoxalat‐Kontakte

Cited by 23 publications

References 7 publications

The Chemistry of the Metal Oxalato Complexes.

The Chemistry of the Metal Oxalato Complexes.

Synthesis of 2‐Isoxazolines: Enantioselective and Racemic Methods Based on Conjugate Additions of Oximes

Combined TPRx, in situ GISAXS and GIXAS studies of model semiconductor-supported platinum catalysts in the hydrogenation of ethene

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