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26.5: Natural Occurrence and Uses of Some Aromatic Side-Chain Compounds

  • Page ID
    22375
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    Derivatives of aromatic aldehydes occur naturally in the seeds of plants. For example, amygdalin is a substance occurring in the seeds of the bitter almond. It is a derivative of gentiobiose, which is a disaccharide made up of two glucose units; one of the glucose unites is bonded by a \(\beta\)-glucoside linkage to the \(\ce{OH}\) group of the cyanohydrin of benzenecarbaldehyde:

    Roberts and Caserio Screenshot 26-5-1.png

    The flavoring vanillin occurs naturally as a glucovanillin (a glucoside) in the vanilla bean (Section 20-5). It is made commercially in several ways. One is from eugenol, itself a constituent of several essential oils:

    Roberts and Caserio Screenshot 26-5-2.png

    Methyl 2-hydroxybenzoate (methyl salicylate, oil of wintergreen) occurs in many plants, but it also is readily prepared synthetically by esterification of 2-hydroxybenzoic acid, which in turn is made from benzenol (see Section 26-1E):

    Roberts and Caserio Screenshot 26-5-4.png

    The ethanoyl derivative of 2-hydroxybenzoic acid is better known as aspirin and is prepared from the acid with ethanoic anhydride, using sulfuric acid as catalyst:

    Roberts and Caserio Screenshot 26-5-5.png
    Figures 23-1 through 23-3.
    Roberts and Caserio Screenshot 26-5-3.png
    Figure 26-2: Some synthetic and natural aromatic compounds and their uses.

    Contributors and Attributions

    John D. Robert and Marjorie C. Caserio (1977) Basic Principles of Organic Chemistry, second edition. W. A. Benjamin, Inc. , Menlo Park, CA. ISBN 0-8053-8329-8. This content is copyrighted under the following conditions, "You are granted permission for individual, educational, research and non-commercial reproduction, distribution, display and performance of this work in any format."