2-Methylheptane

2-Methylheptane is a branched-chain alkane and an isomer of octane. It is an heptane molecule with a methyl group attached to its second atom. It is a flammable colorless liquid used as fuel.

If the standard definition of the prefix "iso-" is strictly used then 2-methylheptane can be called "Isooctane". However this name is usually used for another much more important isomer of octane 2,2,4-trimethylpentane.