Microwave-Assisted Partial Hydrogenation of Citral by using Ionic Liquid-Coated Porous Glass Catalysts

Authors

  • Thomas Gallert,

    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Martin Hahn,

    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Dr. Martin Sellin,

    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Dr. Christine Schmöger,

    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Dr. Achim Stolle,

    Corresponding author
    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
    • Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Prof. Dr. Bernd Ondruschka,

    1. Institute for Technical Chemistry and Environmental Chemistry (ITUC), Friedrich Schiller University Jena, Lessingstraße 12, 07743 Jena (Germany), Fax: (+49) 3641-948402
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  • Dr. Thomas F. Keller,

    1. Institute of Materials Science and Technology (IMT), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany)
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  • Prof. Dr. Klaus D. Jandt

    1. Institute of Materials Science and Technology (IMT), Friedrich Schiller University Jena, Löbdergraben 32, 07743 Jena (Germany)
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Abstract

The microwave-assisted hydrogenation of citral (3,7-dimethylocta-2,6-dienal) to citronellal with molecular hydrogen as the reducing agent was investigated. Several polar and non-polar solvents were screened and imidazolium-based ionic liquids were applied as modifiers for the palladium-containing porous glass catalysts (Pd/TP). The best results were obtained with N-ethyl-N’-methylimidazolium dicyanamide, N-ethyl-N’-methylimidazolium acetate, or N-ethyl-N’-methylimidazolium trifluoroacetate, which were used to prepare supported catalysts with an ionic liquid layer (SCILL) on Pd/TP by wet-impregnation. The influence of pressure and temperature when using these ionic liquid-containing catalysts, as well as their long-term stabilities, were examined. Working with microwave-assisted heating, high yields of citronellal were achieved under mild conditions within short reaction times. Catalyst characterization was carried out by means of BET measurements, X-ray photoelectron spectroscopy (XPS) and thermo-gravimetric analyses. The influences of the ionic liquid layer were derived from experiments carried out before and after the reactions.

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