Trimethylbenzenes
The trimethylbenzenes constitute a group of substances of aromatic hydrocarbons, which structure consists of a benzene ring with three methyl groups (–CH3) as a substituent. Through their different arrangement, they form three structural isomers with the molecular formula C9H12. They also belong to the group of C3-benzenes. The best-known isomer is mesitylene.
...
Wikipedia