Ocimene refers to several isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

ic 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....

s. The ocimenes are monoterpenes

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...

 found within a variety of plants and fruits. α-Ocimene and the two β-ocimenes differ in the position of the isolated double bond: it is terminal in the alpha isomer. α-Ocimene is 3,7-dimethyl-1,3,7-octatriene. β-Ocimene is 3,7-dimethyl-1,3,6-octatriene. β-Ocimene exist in two stereoisomeric forms, cis and trans, with respect to the central double bond. The ocimenes are often found naturally as mixtures of the various forms. The mixture (as well as the pure compounds) is an oil with a pleasant odor. It is used in perfumery. Like the related acyclic terpene myrcene, ocimenes are unstable in air. Like other terpenes, the ocimens are nearly insoluble in water, but soluble in common organic solvents.