ABSTRACT
Mono-and sesquiterpenoids are the chief constituents of essential oils. The essential oils are complex mixtures; however, some may consist mainly of other constituents. Mono- and sesquiterpenoids are of considerable commercial importance. Due to their pleasant smelling nature they are particularly used in the perfumery industry. The essential oils obtained from certain plants contain mostly mono- and sesquiterpenoids. Citral is the most important member of acyclic monoterpenoids and finds many industrial applications. The racemic modification of limonene is known as dipentene. It is a cyclic monoterpenoid. Limonene is optically active. Geraniol is isolated from the oil of palmrosa by treating it with anhydrous calcium chloride and decomposing the crystalline derivative with water. Lycopene is a naturally occurring chemical that gives fruits and vegetables a red colour. It is found in tomatoes, watermelons, red carrots, papaya, apricots and guava. Plant carotenoids are the primary source of provitamin A world wide with β-carotene as the best known provitamin A carotenoid.
