2-Methylpentane

2-Methylpentane, trivially known as isohexane, is a branched-chain alkane with the molecular formula C₆H₁₄. It is a structural isomer of hexane composed of a methyl group bonded to the second carbon atom in a pentane chain.
As of early 1990s, it was present in American and European gasoline in small amounts, and by 2011 its share in US gas varied between 2 and 8%. Using a quantitative structure-activity relationship prediction model, 2-Methylpentane has a research octane number of 75, motor octane number of 77, and cetane number of 29.