Naphthazarin
Naphthazarin, often called 5,8-dihydroxy-1,4-naphthoquinone or 5,8-dihydroxy-1,4-naphthalenedione, is a naturally occurring organic compound with formula, formally derived from 1,4-naphthoquinone through replacement of two hydrogen atoms by hydroxyl groups. It is thus one of many dihydroxynaphthoquinone structural isomers.
Naphthazarin is soluble in 1,4-dioxane 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 and reoxidation.Naphtharazin can also be obtained by oxidation of 5,8-dihydroxy-1-tetralone with manganese dioxide.