Hydroxynaphthoquinone
A hydroxynaphthoquinone (formula: Template:Chem/link) is any of several organic compounds that can be viewed as derivatives of a naphthoquinone through replacement of one hydrogen atom (H) by a hydroxyl group (-OH).
In general, the term may mean any naphthoquinone derivative where any number n of hydrogens have been replaced by n hydroxyls, so that the formula is Template:Chem/link. In this case the number n (which is between 1 and 6) is indicated by a multiplier prefix (mono-, di-, tri-, tetra-, penta-, or hexa-).
The unqualified term "hydroxynaphthoquinone" usually means a derivative of 1,4-naphthoquinone. Other hydroxy- compounds can be derived from other isomers of the latter, such as 1,2-naphthoquinone and 2,6-naphthoquinone. The IUPAC nomenclature uses dihydronaphthalenedione instead of "naphthoquinone", with the necessary prefixes to indicate the positions of the carbonyl oxygens (=O) — as in 5,8-dihydroxy-1a,8a-dihydronaphthalene-1,4-dione (= 5,8-dihydroxy-1,4-naphthoquinone).
The hydroxynaphtoquinones (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][3]
(Mono)hydroxynaphtoquinones
From 1,4-naphthoquinone
Due to its symmetry there are only three isomers:
- 2-Hydroxy-1,4-naphthoquinone (lawsone), coloring principle of henna.
- 5-Hydroxy-1,4-naphthoquinone (juglone), coloring principle of black walnut.[4] Also active antimicrobial principle in Caesalpinia sappan heartwood.[5]
- 6-Hydroxy-1,4-naphthoquinone, can be prepared from 1,7-dihydroxynaphthalene.[6] One of the main products of photochemical oxidation of 1-naphthol.[7]
From 1,2-naphthoquinone
From 1,2-naphthoquinone (ortho-naphthoquinone) there are 6 possible isomers:
- 3-Hydroxy-1,2-naphthoquinone
- 4-Hydroxy-1,2-naphthoquinone[8][9]
- 5-Hydroxy-1,2-naphthoquinone
- 6-Hydroxy-1,2-naphthoquinone
- 7-Hydroxy-1,2-naphthoquinone
- 8-Hydroxy-1,2-naphthoquinone
From 2,3-naphthoquinone
From 2,3-naphthoquinone, also a symmetric molecule there are only three isomers:
From 2,6-naphthoquinone
From the symmetrical 2,6-naphthoquinone (amphi-naphthoquinone) there are only three:
(Poly)hydroxynaphthoquinones
- Dihydroxynaphthoquinone
- Trihydroxynaphthoquinone
- Tetrahydroxynaphthoquinone
- Pentahydroxynaphthoquinone
- Hexahydroxynaphthoquinone
See also
References
<templatestyles src="Reflist/styles.css" />
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "citation/CS1". Quoted by Khalafy and Bruce.
- ↑ Script error: No such module "citation/CS1". Quoted by Khalafy and Bruce.
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
Script error: No such module "Check for unknown parameters".