Density 1.26 g/cm³
|Molar mass 108.0964 g/mol|
Boiling point 213.3 °C
1,2-Benzoquinone, also called ortho-benzoquinone, is an organic compound with formula | C=6 | H=4 | O=2 . It is one of the two isomers of quinone, the other being 1,4-benzoquinone. It is a red volatile solid that is soluble in water and ethyl ether. It is rarely encountered because of its instability, but it is of fundamental interest as the parent ortho-quinone, of which many analogues are known.
The molecule has C2v symmetry. X-ray crystallography shows that the double bonds are localized, with alternatingly long and short C-C distances within the ring. The C=O distances of 1.21 Å are characteristic of ketones.
Preparation and occurrence
1,2-Benzoquinone is produced on oxidation of catechol exposed to air in aqueous solution or by ortho oxidation of a phenol. It is a precursor to melanin.
A strain of the bacterium Pseudomonas mendocina metabolises benzoic acid, yielding 1,2-benzoquinone via catechol.