3-Methylpentane
3-Methylpentane is a branched alkane with the molecular formula C6H14. It is a structural isomer of hexane composed of a methyl group bonded to the third carbon atom in a pentane chain. It is of similar structure to the isomeric 2-methylpentane, which has the methyl group located on the second carbon of the 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 1.5 and 6% It has close research and motor octane numbers of 74.5 and 74.3.