Dihydroxynaphthoquinone

A dihydroxynaphthoquinone (formula: C
10H
6O
4) 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-).

Isomers

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).^[1]
• 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

See also

• Hydroxynaphthoquinone
• Trihydroxynaphthoquinone
• Dihydroxyanthraquinone

References

1. J. Khalafy and J.M. Bruce (2002), Oxidative dehydrogenation of 1-tetralones: Synthesis of juglone, naphthazarin, and α-hydroxyanthraquinones. Journal of Sciences, Islamic Republic of Iran, volume 13 issue 2, pages 131-139.