2-Methylbutane

Isopentane, also called methylbutane or 2-methylbutane, is a branched-chain saturated hydrocarbon (an alkane) with five carbon atoms, with formula C
₅H
₁₂ or CH(CH
₃)
₂(C
₂H
₅).

Isopentane is an extremely volatile and extremely flammable liquid at room temperature and pressure. It is also the least dense liquid at standard conditions.^{[citation needed]} The normal boiling point is just a few degrees above room temperature and isopentane will readily boil and evaporate away on a warm day.

Isopentane is commonly used in conjunction with liquid nitrogen to achieve a liquid bath temperature of −160 °C. Natural gas typically contains 1% or less isopentane,but it is a significant component of natural gasoline.^[4]