Ethylbenzene

Ethylbenzene is ${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{C}{\mathrm{H}}_2\mathrm{C}{\mathrm{H}}_3$, a benzene ring carrying an ethyl substituent. It shares the formula ${\mathrm{C}}_8{\mathrm{H}}_{10}$ with the xylene isomers but has different connectivity.

Conversion of its side chain to a vinyl group gives styrene, connecting a simple aromatic hydrocarbon with an important polymer starting material. Its benzylic carbon also has reactivity distinct from the ring itself.