18cineole

1,8-Cineole, commonly known as eucalyptol, is a cyclic monoterpene ether that occurs widely in essential oils. It is a colorless liquid with a distinctive camphor-like aroma and is one of the major, sometimes dominant, components of eucalyptus oil. The compound exists as two enantiomers, which can have slightly different sensory properties.

Chemical and physical properties: The molecular formula is C10H18O, and its molecular weight is about 154.25 g/mol. It is a lipophilic compound with a boiling point near 176°C and a relatively low vapor pressure at room temperature. Its structure features a single oxygen atom incorporated into a bicyclic ether ring, giving it characteristic olfactory and reactivity attributes of many monoterpenes.

Occurrence and production: 1,8-Cineole is abundant in Eucalyptus essential oils, especially from Eucalyptus globulus. It is also present in appreciable amounts in oils from other plants such as rosemary, sage, bay laurel, and tea tree. Industrially it is isolated or enriched from plant distillates for use in flavors and fragrances.

Applications: It is widely used as a fragrance and flavoring agent in foods, beverages, cosmetics, and oral care products. In medicinal and consumer contexts, it appears in cough syrups, lozenges, inhalants, and topical preparations for its scent and potential soothing effects. It is often the dominant scent component in eucalyptus-based products and contributes to the characteristic medicinal aroma of many essential oils.

Pharmacology and safety: 1,8-Cineole has been studied for anti-inflammatory, antimicrobial, and bronchodilatory properties, though results are variable and context-dependent. In general, it is considered safe at low concentrations for flavor and fragrance use, but higher concentrations or essential oil preparations can cause irritation or adverse reactions in some individuals. Ingestion of concentrated essential oil is not recommended, and exposure should be minimized for pets and sensitive populations. Regulatory status varies by jurisdiction; it is commonly approved as a flavoring and fragrance ingredient.