The C<sub>3</sub>-benzenes are a class of organic aromatic compounds which contain a benzene ring and three other carbon atoms. For the hydrocarbons with no further unsaturation, there are four isomers. The chemical formula for all the saturated isomers is C<sub>9</sub>H<sub>12</sub>. There are three trimethylbenzenes, three ethylmethylbenzenes, and two propylbenzene isomers. 1980s American gasoline contained about 3-4% C<sub>3</sub>-benzenes.