Benzene is the simplest of the aromatic hydrocarbons. It is a ring structure with the empirical formula C₆H₆. Benzene was first discovered by Michael Faraday in 1825 from the liquid condensed by compressing oil gas.

The chemical structure of the molecule was originally worked out by Kekulé in 1865. The structure of benzene is formally that of a regular hexagonal array of the carbon atoms, termed a ring structure, comprising three alternating carbon-carbon double bonds and three carbon-carbon single bonds. The electrons of the double bond are now known not to be static, however, but form a symmetrical "-cloud" molecular orbital above and below the ring where these electrons are delocalized (or resonating) around the ring. This resonance strongly stabilizes benzene and profoundly influences its chemical properties.

Benzene is a clear, highly refractive liquid at standard temperature and pressure with a characteristic, sweet smell. It is highly flammable...