Isobutane, also known as i-butane, 2-methylpropane or methylpropane, is a chemical compound with molecular formula HC(CH₃)₃. It is an isomer of butane. Isobutane is a colourless, odourless gas. It is the simplest alkane with a tertiary carbon atom. R600a is an HFC-free refrigerant with no ozone depletion potential and a lower global warming potential compared to earlier refrigerants.