Hydroxybenzoquinone

A hydroxybenzoquinone (formula: C
6H
4O
3) is any of several organic compounds that can be viewed as derivatives of a benzoquinone through replacement of one hydrogen atom (H) by an hydroxyl group (-OH).

In general, the term may mean any benzoquinone derivative where any number n of hydrogens have been replaced by n hydroxyls, so that the formula is C
6H
4O
2+n. In this case the number n (which is between 1 and 4) is indicated by a multiplier prefix (mono-, di-, tri-, tetra-, penta-, or hexa-).

The unqualified term "hydroxybenzoquinone" usually means a derivative of 1,4-benzoquinone. Other hydroxy- compounds can be derived from the other isomer, namely 1,2-benzoquinone or ortho-benzoquinone. The IUPAC nomenclature uses dihydrobenzenedione instead of "benzoquinone", with the necessary prefixes to indicate the positions of the carbonyl oxygens (=O) — as in 2,3-dihydroxy-1a,4a-dihydrobenzene-1,4-dione (= 2,3-dihydroxy-1,4-benzoquinone).

The hydroxybenzoquinones (in the particular or the general sense) include many biologically and industrially important compounds, and are a building block of many medicinal drugs.^{[1] [2]}

List of compounds

From 1,4-benzoquinone

Due to the symmetry of the 1,4-benzoquinone (para-benzoquinone) core, there is only one distinct isomer with 1, 3, or 4 substituted hydroxyls, and three isomers with 2 hydroxyls:

• 2-Hydroxy-1,4-benzoquinone (C
  6H
  4O
  3)
• 2,3-Dihydroxy-1,4-benzoquinone (C
  6H
  4O
  4)
• 2,5-Dihydroxy-1,4-benzoquinone (C
  6H
  4O
  4)
• 2,6-Dihydroxy-1,4-benzoquinone (C
  6H
  4O
  4)
• 2,3,5-Trihydroxy-1,4-benzoquinone (C
  6H
  4O
  5)
• 2,3,5,6-Tetrahydroxy-1,4-benzoquinone (C
  6H
  4O
  6)

From 1,2-benzoquinone

From the less symmetrical 1,2-benzoquinone (ortho-benzoquinone) there are 9 possible isomers:

• 3-Hydroxy-1,2-benzoquinone (C
  6H
  4O
  3)
• 4-Hydroxy-1,2-benzoquinone (C
  6H
  4O
  3)
• 3,4-Dihydroxy-1,2-benzoquinone (C
  6H
  4O
  4)
• 3,5-Dihydroxy-1,2-benzoquinone (C
  6H
  4O
  4)
• 3,6-Dihydroxy-1,2-benzoquinone (C
  6H
  4O
  4)
• 4,5-Dihydroxy-1,2-benzoquinone (C
  6H
  4O
  4)
• 3,4,5-Trihydroxy-1,2-benzoquinone (C
  6H
  4O
  5)
• 3,4,6-Trihydroxy-1,2-benzoquinone (C
  6H
  4O
  5)
• 3,4,5,6-Tetrahydroxy-1,2-benzoquinone (C
  6H
  4O
  6)

See also

• Chloranilic acid (2,5-dichloro-3,6,-dihydroxy-1,4-benzoquinone)
• Hydroxynaphthoquinone
• Hydroxyanthraquinone
• Hydroxyquinone
• C6H4O3
• C6H4O4
• C6H4O5
• C6H4O6

References

1. Thomson R.H. Naturally Occurring Quinones. Academic Press, London (1971). Quoted by Khalafy and Bruce.
2. Thomson R.H. Naturally Occurring Quinones III. Chapman and Hall, London (1987). Quoted by Khalafy and Bruce.