Claus' benzene (C₆H₆) is a hypothetical

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...

and an

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms, ...

. It was proposed by Adolf Karl Ludwig Claus in 1867 as a possible structure for benzene at a time when the structure of benzene was still being debated. The molecule can be described as a hexagon with carbon atoms positioned at the corners, with each carbon connected to its two ''ortho'' carbons (the nearest carbons) and the one ''para'' carbon connected diametrically. High

strain energy In physics, the elastic potential energy gained by a wire during elongation with a tensile (stretching) force is called strain energy. For Linear elasticity, linearly elastic materials, strain energy is: : U = \frac 1 2 V \sigma \epsilon = \frac ...

makes its synthesis impossible. Although it is often referred to alongside

Dewar benzene Dewar benzene (also spelled ''dewarbenzene'') or bicyclo .2.0exa-2,5-diene is a bicyclic isomer of benzene with the molecular formula C6H6. The compound is named after James Dewar who included this structure in a list of possible C6H6 structures in ...

and

prismane Prismane or 'Ladenburg benzene' is a polycyclic hydrocarbon with the formula C6H6. It is an isomer of benzene, specifically a valence isomer. Prismane is far less stable than benzene. The carbon (and hydrogen) atoms of the prismane molecule are a ...

, it is not possible to synthesise it, while Dewar benzene and prismane can be.

References

Isomerism Hypothetical chemical compounds {{theoretical-chem-stub