Which alkane is the isomer of butane called 2-methylpropane?

The isomer of butane called 2-methylpropane is known as isobutane. It has a chemical formula written C4H10 and is known as the simplest alkane having a tertiary carbon. It was used as a refrigerant and known as R-600a. However, towards the end of 2009, it was suggested that the use of such in refrigerators is dangerous. A number of explosion of refrigerators were reported and it was suspected that the cause is the leaking of isobutane and being ignited by the electrical system. At that point, the use of such as refrigerant was discouraged and was being replace by safer refrigerants. Isobutane is also being used as a raw material in the petrochemical industry like in the synthesis of the fuel isooctane.