Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH3CH2CH2CH3. Butane is also used as a collective term for n-butane together with its only other isomer, isobutane (also called methylpropane), CH(CH3)3.
Butanes are highly flammable, colorless, easily liquefied gases. The name butane was derived by back-formation from the name of butyric acid.