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


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:

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:

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):

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: