Cymene, or p-cymene, is a naturally occurring aromatic organic compound

Organic compound

An organic compound is any member of a large class of gaseous, liquid, or solid chemical compounds whose molecules contain carbon. For historical reasons discussed below, a few types of carbon-containing compounds such as carbides, carbonates, simple oxides of carbon, and cyanides, as well as the...

. It is classified as a hydrocarbon

Hydrocarbon

In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....

 related to a monoterpene

Terpene

Terpenes are a large and diverse class of organic compounds, produced by a variety of plants, particularly conifers, though also by some insects such as termites or swallowtail butterflies, which emit terpenes from their osmeterium. They are often strong smelling and thus may have had a protective...

. Its structure consists of a benzene ring para-substituted with a methyl group and an isopropyl group. It is insoluble in water, but miscible with ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug and one of the oldest recreational drugs. Best known as the type of alcohol found in alcoholic beverages, it is also used in thermometers, as a...

 and ether

Diethyl ether

Diethyl ether, also known as ethyl ether, simply ether, or ethoxyethane, is an organic compound in the ether class with the formula . It is a colorless, highly volatile flammable liquid with a characteristic odor...

.

Cymene is a constituent of a number of essential oil

Essential oil

An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...

s, most commonly the oil of cumin

Cumin

Cumin is a flowering plant in the family Apiaceae, native from the east Mediterranean to India. Its seeds are used in the cuisines of many different cultures, in both whole and ground form.-Etymology:...

 and thyme

Thyme

Thyme is a culinary and medicinal herb of the genus Thymus.-History:Ancient Egyptians used thyme for embalming. The ancient Greeks used it in their baths and burnt it as incense in their temples, believing it was a source of courage...

.

There are two less common geometric isomers. o-Cymene, in which the alkyl groups are ortho-substituted, and m-cymene, in which they are meta-substituted. p-Cymene is the only natural isomer.

Cymene is a common ligand for ruthenium. The parent compound is [(η⁶-cymene)RuCl₂]₂

(Cymene)ruthenium dichloride dimer

ruthenium dichloride dimer is the organometallic compound with the formula [RuCl2]2. This red-coloured, diamagnetic solid is a reagent in organometallic chemistry and homogeneous catalysis.-Preparation and reactions:...

. This half-sandwich compound

Sandwich compound

In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by haptic covalent bonds to two arene ligands. The arenes have the formula CnHn, substituted derivatives and heterocyclic derivatives...

 is prepared by the reaction of ruthenium trichloride with the terpene α-phellandrene

Phellandrene

Phellandrene is the name for a pair of organic compounds that have a similar molecular structure and similar chemical properties. α-Phellandrene and β-phellandrene are cyclic monoterpenes and are double-bond isomers. In α-phellandrene, both double bonds are endocyclic and in β-phellandrene, one...

. The osmium complex is also known.

Significant amounts of cymene are formed in sulfite pulping process from the wood terpenes.