2,2,4-Trimethylpentane, also known as
isooctane or
iso-octane, is an
organic compound with the formula (CH
3)
3CCH
2CH(CH
3)
2. It is one of several
isomers of
octane (C
8H
18). This particular isomer is the standard 100 point on the
octane rating scale (the zero point is
n-heptane). It is an important component of
gasoline, frequently used in relatively large proportions to increase the
knock resistance of the fuel.