1,4-Dihydroxyanthraquinone

1,4-Dihydroxyanthraquinone, also called quinizarin or Solvent Orange 86, is an organic compound derived from anthroquinone. Quinizarin is an orange or red-brown crystalline powder. It is formally derived from anthraquinone by replacement of two hydrogen atoms by hydroxyl (OH) groups. It is one of ten dihydroxyanthraquinone isomers and occurs in small amounts (as a glycoside) in the root of the madder plant, Rubia tinctorum.^[1]

1,4-Dihydroxyanthraquinone

Skeletal formula
Ball-and-stick model
Names
Preferred IUPAC name 1,4-Dihydroxyanthracene-9,10-dione
Other names Quinizarin; Solvent Orange 86
Identifiers
CAS Number	81-64-1 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:37487 Y
ChEMBL	ChEMBL17594 Y
ChemSpider	6433 Y
ECHA InfoCard	100.001.245
PubChem CID	6688
UNII	8S496ZV3CS Y
CompTox Dashboard (EPA)	DTXSID8044464
InChI InChI=1S/C14H8O4/c15-9-5-6-10(16)12-11(9)13(17)7-3-1-2-4-8(7)14(12)18/h1-6,15-16H Y Key: GUEIZVNYDFNHJU-UHFFFAOYSA-N Y InChI=1/C14H8O4/c15-9-5-6-10(16)12-11(9)13(17)7-3-1-2-4-8(7)14(12)18/h1-6,15-16H Key: GUEIZVNYDFNHJU-UHFFFAOYAX
SMILES O=C2c1ccccc1C(=O)c3c2c(O)ccc3O
Properties
Chemical formula	C14H8O4
Molar mass	240.21 g/mol
Appearance	Orange or red-brown crystalline powder
Melting point	198 to 199 °C (388 to 390 °F; 471 to 472 K)
Boiling point	450 °C (842 °F; 723 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is YN ?) Infobox references

Production

Quinizarin is produced by the reaction of phthalic anhydride and 4-chlorophenol followed by hydrolysis of the chloride:^[2][3]

Summary equation for one synthesis of alizarin.[sic.]

It can also be prepared less efficiently from phthalic anhydride and hydroquinone.^{[citation needed]}

Uses

Quinizarin is an inexpensive dye that is used to colour gasoline and some heating oils. It is used as an intermediate for the synthesis of indanthrene- and alizarin-derived dyes. The OH groups can be replaced by chloride. Chlorination and bromination afford other dyes. Amination (replacement of one OH by ArNH) with aniline derivatives followed by sulfonation affords other dyes such as Acid Violet 43. It is also used to form lake pigments with calcium, barium, and lead.^[2]

Quinizarin sample (Historic Dye Collection of TU Dresden).

See also

• Hydroxyanthraquinone
• 1,2-Dihydroxyanthraquinone (alizarin)
• 1,3-Dihydroxyanthraquinone (purpuroxanthin)
• Trihydroxyanthraquinone
• Quinalizarin (1,2,5,8-tetrahydroxyanthraquinone)