Congo red

Congo red
Names
	IUPAC name disodium 4-amino-3-[4-[4-(1-amino-4-sulfonato-naphthalen-2-yl)diazenylphenyl]phenyl]diazenyl-naphthalene-1-sulfonate
Identifiers
CAS Number	573-58-0 ;
3D model (JSmol)	Interactive image;
ChEMBL	ChEMBL429694 ;
ChemSpider	10838 ;
ECHA InfoCard	100.008.509
MeSH	Congo+red
PubChem CID	11313;
UNII	3U05FHG59S ;
CompTox Dashboard (EPA)	DTXSID4022816 ;
	InChI InChI=1S/C32H24N6O6S2.2Na/c33-31-25-7-3-1-5-23(25)29(45(39,40)41)17-27(31)37-35-21-13-9-19(10-14-21)20-11-15-22(16-12-20)36-38-28-18-30(46(42,43)44)24-6-2-4-8-26(24)32(28)34;;/h1-18H,33-34H2,(H,39,40,41)(H,42,43,44);;/q;2+1/p-2/b37-35+,38-36+;; Key: IQFVPQOLBLOTPF-HKXUKFGYSA-L ; InChI=1/C32H24N6O6S2.2Na/c33-31-25-7-3-1-5-23(25)29(45(39,40)41)17-27(31)37-35-21-13-9-19(10-14-21)20-11-15-22(16-12-20)36-38-28-18-30(46(42,43)44)24-6-2-4-8-26(24)32(28)34;;/h1-18H,33-34H2,(H,39,40,41)(H,42,43,44);;/q;2+1/p-2/b37-35+,38-36+;; Key: IQFVPQOLBLOTPF-COCKEIKOBB;
	SMILES [Na+].[Na+].[O-]S(=O)(=O)c5cc(/N=N/c1ccc(cc1)c4ccc(/N=N/c3cc(c2ccccc2c3N)S([O-])(=O)=O)cc4)c(N)c6c5cccc6;
Properties
Chemical formula	C32H22N6Na2O6S2
Molar mass	696.665
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Congo red is an organic compound, the sodium salt of 3,3′-([1,1′-biphenyl]-4,4′-diyl)bis(4-aminonaphthalene-1-sulfonic acid). It is an azo dye. Congo red is water-soluble, yielding a red colloidal solution; its solubility is greater in organic solvents. The use of Congo red in the textile industry has long been abandoned, primarily because of its carcinogenic properties, but it is still used for histological staining.