Isobutane

Isobutane, also known as methylpropane or 2-methylpropane, is an alkane, isomeric with butane. Recent concerns with depletion of the ozone layer by freon gases have led to increased use of isobutane as a gas for refrigeration systems, especially in domestic refrigerators and freezers, and as a propellant in aerosol sprays. When used as a refrigerant or a propellant, isobutane is also known as R-600a. It is used as a feedstock in the petrochemical industry, for example in the synthesis of isooctane.

Nomenclature
Isobutane is the trivial name retained by the International Union of Pure and Applied Chemistry (IUPAC) in its 1993 Recommendations for the Nomenclature of Organic Chemistry.

Methylpropane is the systematic name. The substituent number (2-) is unnecessary because there is no isomer of this molecule with methylpropane as part of its name.