Illustrated Glossary of Organic Chemistry

Benzyne: A benzene ring in which two of the carbon atoms have an unpaired electron.

Molecular structure of o-benzyne (more frequently called benzyne). Because the orbitals hosting the two unpaired electrons are on adjacent carbons and can therefore overlap, benzyne is shown having one more pi bond than benzene itself.

The two unpaired electrons of m-benzyne have a meta relationship.

Bergman cyclization of (Z)-hexa-3-en-1,5-diyne (an enediyne) gives p-benzyne.