Noun
isobutane (countable and uncountable, plural isobutanes)
(organic chemistry) A hydrocarbon, a particular isomer of C4H10 found in natural gas.
For example, compare isobutane (2-methylpropane) and n-butane (butane), which boil at −12 and 0 °C, and 2,2-dimethylbutane and 2,3-dimethylbutane which boil at 50 and 58 °C, respectively. Source: Internet
For example, isobutane may be written (CH 3 ) 3 CH. Source: Internet