Oxepin is an oxygen-containing heterocycle consisting of a seven-membered ring with three double bonds.
The parent C6H6O exists as an equilibrium mixture with benzene oxide.
The oxepin–benzene oxide equilibrium is affected by the ring substituents.
[1] A related dimethyl derivative exists mainly as the oxepin isomer, an orange liquid.
[2] Oxepin is an intermediate in the oxidation of benzene by the cytochrome P450 (CYP).