HRGC separation of hydroperoxides formed during the photosensitized oxidation of (R)—(+)-Limonene

Authors

  • P. Schieberle,

    1. Deutsche Forschungsanstalt für Lebensmittelchemie and Kurt-Hess-Institut für Mehl- and Eiweißforschung, Lichtenbergstraße 4, D-8046 Garchina, FRG
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  • W. Maier,

    1. Institut für Organische Chemie der Technischen Universität München, Lichtenbergstraße 4, D-8046 Garching, FRG
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  • J. Firl,

    1. Institut für Organische Chemie der Technischen Universität München, Lichtenbergstraße 4, D-8046 Garching, FRG
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  • W. Grosch

    Corresponding author
    1. Deutsche Forschungsanstalt für Lebensmittelchemie and Kurt-Hess-Institut für Mehl- and Eiweißforschung, Lichtenbergstraße 4, D-8046 Garchina, FRG
    • Deutsche Forschungsanstalt für Lebensmittelchemie and Kurt-Hess-Institut für Mehl- and Eiweißforschung, Lichtenbergstraße 4, D-8046 Garchina, FRG
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Abstract

(R)—(+)-Limonene was photooxidized in the presence of Rose Bengal as catalyst. After TLC isolation, the hydroperoxides formed were separated directly by HRGC and analyzed by MS (El; Cl). Each hydroperoxide isomer was then isolated by HPLC for structure determination which after reduction of the HOO group with sodium borohydride was performed by 1H-NMR and 13C-NMR.

Six hydroperoxide isomers formed by oxidation of the endocyclic double bond were identified. The compounds eluted from the HRGC column in the following order (proportions are given in brackets) I (40.1%) (1S, 4R)-p-mentha-2, 8-diene 1-hydroperoxide; II (5.8%) (1R, 4R)-p-mentha-2, 8-diene 1-hydroperoxide; III (20.6%) (2R, 4R)-p-mentha-[1(7), 8]-diene 2-hydroperoxide; IV (8.5%) (2R, 4R)-p-mentha-6, 8-diene 2-hydroperoxide; V (4%) (2S, 4R)-p-mentha-6, 8-diene 2-hydroperoxide; and VI (21.0%) (2S, 4R)-p-mentha-[1(7), 8]-diene 2-hydroperoxide. Direct HRGC separation of the limonene hydroperoxides offers, inter alia, the possibility of determining their flavor qualities by HRGC/effluent sniffing.

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