Dihydroxynaphthoquinone

A dihydroxynaphthoquinone (formula: ) is any of several organic compounds that can be viewed as derivatives of naphthoquinone through replacement of two hydrogen atoms (H) by hydroxyl groups (OH).

The unqualified term "dihydroxynaphthoquinone" usually means a derivative of 1,4-naphthoquinone. Other dihydroxy- compounds can be derived from the two other known isomers, 1,2-naphthoquinone (ortho-) and 2,6-naphthoquinone (amphi-).

From 1,4-naphthoquinone
Due to the symmetry of the parent quinone, there are only nine distinct isomers of dihydroxy-1,4-naphthoquinone:
 * 2,3-Dihydroxy-1,4-naphthoquinone.
 * 2,5-Dihydroxy-1,4-naphthoquinone.
 * 2,6-Dihydroxy-1,4-naphthoquinone.
 * 2,7-Dihydroxy-1,4-naphthoquinone.
 * 2,8-Dihydroxy-1,4-naphthoquinone.
 * 5,6-Dihydroxy-1,4-naphthoquinone.
 * 5,7-Dihydroxy-1,4-naphthoquinone.
 * 5,8-Dihydroxy-1,4-naphthoquinone (naphthazarin).
 * 6,7-Dihydroxy-1,4-naphthoquinone.

From 1,2-naphthoquinone
From 1,2-naphthoquinone there are 12 possible dihydroxy- isomers:
 * 3,4-Dihydroxy-1,2-naphthoquinone
 * 3,5-Dihydroxy-1,2-naphthoquinone
 * 3,6-Dihydroxy-1,2-naphthoquinone
 * 3,7-Dihydroxy-1,2-naphthoquinone
 * 3,8-Dihydroxy-1,2-naphthoquinone
 * 4,5-Dihydroxy-1,2-naphthoquinone
 * 4,6-Dihydroxy-1,2-naphthoquinone
 * 4,7-Dihydroxy-1,2-naphthoquinone
 * 4,8-Dihydroxy-1,2-naphthoquinone
 * 5,6-Dihydroxy-1,2-naphthoquinone
 * 5,7-Dihydroxy-1,2-naphthoquinone
 * 5,8-Dihydroxy-1,2-naphthoquinone
 * 6,7-Dihydroxy-1,2-naphthoquinone
 * 6,8-Dihydroxy-1,2-naphthoquinone
 * 7,8-Dihydroxy-1,2-naphthoquinone

From 2,6-naphthoquinone
From the symmetrical 2,6-naphthoquinone there are only nine dihydroxy- isomers:
 * 1,3-Dihydroxy-2,6-naphthoquinone
 * 1,4-Dihydroxy-2,6-naphthoquinone
 * 1,5-Dihydroxy-2,6-naphthoquinone
 * 1,7-Dihydroxy-2,6-naphthoquinone
 * 1,8-Dihydroxy-2,6-naphthoquinone
 * 3,4-Dihydroxy-2,6-naphthoquinone
 * 3,7-Dihydroxy-2,6-naphthoquinone
 * 3,8-Dihydroxy-2,6-naphthoquinone
 * 4,8-Dihydroxy-2,6-naphthoquinone