Naphthazarin, often called 5,8-dihydroxy-1,4-naphthoquinone or 5,8-dihydroxy-1,4-naphthalenedione (

IUPAC The International Union of Pure and Applied Chemistry (IUPAC ) is an international federation of National Adhering Organizations working for the advancement of the chemical sciences, especially by developing nomenclature and terminology. It is ...

), is a naturally occurringThomson R.H. Naturally Occurring Quinones. Academic Press, London (1971). Quoted by Khalafy and Bruce.Thomson R.H. Naturally Occurring Quinones III. Chapman and Hall, London (1987). Quoted by Khalafy and Bruce.

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The ...

with formula , formally derived from 1,4-naphthoquinone through replacement of two

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...

atoms by

hydroxyl In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy ...

(OH) groups. It is thus one of many

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" usua ...

structural isomer In chemistry, a structural isomer (or constitutional isomer in the IUPAC nomenclature) of a chemical compound, compound is another compound whose molecule has the same number of atoms of each element, but with logically distinct chemical bond, b ...

s. Naphthazarin is soluble in

1,4-dioxane 1,4-Dioxane () is a heterocyclic organic compound, classified as an ether. It is a colorless liquid with a faint sweet odor similar to that of diethyl ether. The compound is often called simply dioxane because the other dioxane isomers ( 1,2- ...

from which it crystallizes as deep red needles that melt at 228−232 °C.

Synthesis

Naphtharazin can be prepared by condensation of 1,4-dimethoxybenzene with 2,3-dichloromaleic anhydride followed by reductive

dechlorination In organochlorine chemistry, reductive dechlorination describes any chemical reaction which cleaves the covalent bond between carbon and chlorine via reductants, to release chloride ions. Many modalities have been implemented, depending on the ap ...

and re

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

.Lewis J.R. and Paul J.J.(1977). Z. Naturforsch., B, 32: 1473. Quoted by Khalafy and Bruce.Huot R. and Brassard P. (1974). Can. J. Chem., 52: 838. Quoted by Khalafy and Bruce. Naphtharazin can also be obtained by oxidation of 5,8-dihydroxy-1-tetralone with

manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell ...

(MnO₂).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.

References

{{reflist 1,4-Naphthoquinones Hydroquinones Hydroxynaphthoquinones 3-Hydroxypropenals within hydroxyquinones