1,2-Benzoquinone, also called ''ortho''-benzoquinone, is an
organic compound
Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...
with formula . It is one of the two isomers of
quinone
The quinones are a class of organic compounds that are formally "derived from aromatic compounds benzene.html" ;"title="uch as benzene">uch as benzene or naphthalene] by conversion of an even number of –CH= groups into –C(=O)– groups with ...
, the other being
1,4-benzoquinone
1,4-Benzoquinone, commonly known as ''para''-quinone, is a chemical compound with the chemical formula, formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, ...
. It is a red volatile solid that is soluble in water and
diethyl ether
Diethyl ether, or simply ether, is an organic compound with the chemical formula , sometimes abbreviated as . It is a colourless, highly Volatility (chemistry), volatile, sweet-smelling ("ethereal odour"), extremely flammable liquid. It belongs ...
. It is rarely encountered because of its instability, but it is of fundamental interest as the parent compound of many
derivatives which are known.
Structure
The molecule has C 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 reactions
1,2-Benzoquinone is produced on oxidation of
catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It ...
exposed to air in aqueous solution
[ or by ortho oxidation of a ]phenol
Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire.
The molecule consists of a phenyl group () ...
.
A strain of the bacterium
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among the ...
''Pseudomonas mendocina
''Pseudomonas mendocina'' is a Gram-negative environmental bacterium that can cause opportunistic infections, such as infective endocarditis and spondylodiscitis, although cases are very rare. It has potential use in bioremediation as it is able ...
'' metabolises benzoic acid
Benzoic acid () is a white (or colorless) solid organic compound with the formula , whose structure consists of a benzene ring () with a carboxyl () substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn," which ...
, yielding 1,2-benzoquinone via catechol
Catechol ( or ), also known as pyrocatechol or 1,2-dihydroxybenzene, is an organic compound with the molecular formula . It is the ''ortho'' isomer of the three isomeric benzenediols. This colorless compound occurs naturally in trace amounts. It ...
.
Ortho-quinones are widely used in organic synthesis
Organic synthesis is a branch of chemical synthesis concerned with the construction of organic compounds. Organic compounds are molecules consisting of combinations of covalently-linked hydrogen, carbon, oxygen, and nitrogen atoms. Within the gen ...
.
Occurrence of ''ortho''-quinones
4,5-Dimethyl-1,2-benzoquinone, also a red solid, is a well behaved synthetic ''ortho''-quinone.
The biological pigment melanin
Melanin (; ) is a family of biomolecules organized as oligomers or polymers, which among other functions provide the pigments of many organisms. Melanin pigments are produced in a specialized group of cells known as melanocytes.
There are ...
is rich in ''ortho''-quinones.
Finally, the enzyme cofactors tryptophan tryptophylquinone (TTQ), cysteine tryptophylquinone (CTQ), lysine tyrosylquinone (LTQ) and pyrroloquinoline quinone (PQQ) contain the ''ortho''-quinone moiety in their chemical structure.
See also
*1,4-Benzoquinone
1,4-Benzoquinone, commonly known as ''para''-quinone, is a chemical compound with the chemical formula, formula C6H4O2. In a pure state, it forms bright-yellow crystals with a characteristic irritating odor, resembling that of chlorine, bleach, ...
References
{{DEFAULTSORT:Benzoquinone, 1, 2-
Enones
ja:ベンゾキノン#1,2-ベンゾキノン