Cymene

cymene

[′sī‚mēn]

(organic chemistry)

Any of the isomeric hydrocarbons metacymene, paracymene, and orthocymene; paracymene is a liquid that is colorless, has a pleasant odor, and is made from oil of cumin or oil of wild thyme.

Cymene

 

(also methyl-isopropyl-benzene), an aromatic hydrocarbon having the structural formula

The meta-, ortho-, and para-isomers of cymene are known; the most important is para-cymene, which is a component of turpentine and many essential oils, including cumin oil and eucalyptus oil. A colorless liquid with a characteristic odor, para-cymene has a boiling point of 177.1°C, a melting point of –67.9°C, and a density of 0.857 g/cm³ at 20°C. Cymene is insoluble in water, but it is miscible with many organic solvents.

The similarity of the carbon skeleton of para-cymene with the skeletons of many cyclic terpenes is a result of their common origin. Thus, para-cymene may be produced by the pyrolysis of α-pinene, the dehydrogenation of limonene, or the heating of camphor with P₂O₅. In the chemical industry, para-cymene is produced from sulfite turpentine and is used as a raw material and a solvent.