Methylcyclopentane is an organic compound with the chemical formula CH3C5H9. It is a colourless, flammable liquid with a faint odor. It is a component of the naphthene fraction of petroleum usually obtained as a mixture with cyclohexane. It is mainly converted in naphthene reformers to benzene. As of early 1990s, it was present in American and European gasoline in small amounts. It has a research octane number of 103 and motor octane number of 95. The C6 core of methylcyclopentane is not perfectly planar and can pucker to alleviate stress in its structure.

History

Methylcyclopentane was first synthesized in 1888 by Paul Caspar Freer and W. H. Perkin Jr. by a Wurtz reaction of sodium and 1,5-dibromohexane. They named it methylpentamethylene since the modern nomenclature wasn't developed until 1892 Geneva Rules. In 1895, Nikolai Kischner discovered that methylcyclopentane was the reaction product of hydrogenation of benzene using hydriodic acid. Prior to that, several chemists (such as Marcellin Berthelot in 1867, and Adolf von Baeyer in 1870 ) had tried and failed to synthesize cyclohexane using this method.