1,4-Dihydroxyanthraquinone

Yellow flakes or deep red needles

Fixed

194-196 ° C or 200-202 ° C

Soluble in water, ethanol, diethyl ether and benzene

Attention

> 5000 mg · kg -1 ( LD50, mouse, oral)

Template: Infobox chemical / molecular formula search available

Quinizarin is an organic chemical aromatic compound. There is a related anthraquinone dye Alizarin.

Representation

In the literature, a number of synthetic possibilities are described. Quinizarin can be recovered from the reaction between phthalic anhydride and hydroquinone. As a Lewis acid, aluminum chloride can be used for this purpose. Another synthetic route is given by the reaction of 1,4 -dihydroxynaphthalene with maleic anhydride and aluminum chloride.

Use

The dye is orange in its protonated form. With the addition of hydroxide ions, the dye turns purple. Thus, it can be used as a pH indicator.