Solvent Red 164

Sudan III

Names
IUPAC name 1-(4-(phenyldiazenyl)phenyl) azonaphthalen-2-ol
Identifiers
CAS Number	85-86-9 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:82535 N
ChemSpider	16736189 Y
ECHA InfoCard	100.001.490
KEGG	C19527 N
UNII	ND733RX3JN Y
InChI InChI=1S/C22H16N4O/c27-21-15-10-16-6-4-5-9-20(16)22(21)26-25-19-13-11-18(12-14-19)24-23-17-7-2-1-3-8-17/h1-15,27H/b24-23-,26-25+ Y Key: FHNINJWBTRXEBC-HXEHWPEMSA-N Y InChI=1/C22H16N4O/c27-21-15-10-16-6-4-5-9-20(16)22(21)26-25-19-13-11-18(12-14-19)24-23-17-7-2-1-3-8-17/h1-15,27H/b24-23-,26-25+ Key: FHNINJWBTRXEBC-HXEHWPEMBU
SMILES Oc4ccc1ccccc1c4/N=N/c3ccc(\N=N/c2ccccc2)cc3
Properties
Chemical formula	C22H16N4O
Molar mass	352.39 g/mol
Melting point	199 °C (390 °F; 472 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Sudan III is a lysochrome (fat-soluble dye) diazo dye. It is structurally related to azobenzene.

It is used to color nonpolar calamaro substances like oils, fats, waxes, greases, various hydrocarbon products, and acrylic emulsions. Its main use is as a fuel dye in the United States of America mandated by the IRS to distinguish low-taxed heating oil from automotive diesel fuel, and by the EPA to mark fuels with higher sulfur content; it is a replacement for Solvent Red 26 with better solubility in hydrocarbons. The concentration required by IRS is a spectral equivalent of 3.9 pounds per 1000 barrels, or 11.13 mg/l, of Solvent Red 26 in solid form; the concentrations required by EPA are roughly 5 times lower.

It is also used to dye some hydraulic fluids and some other hydrocarbons, predominantly gasoline.

Sudan III is a dye used for Sudan staining. Similar dyes include Oil Red O, Sudan IV, and Sudan Black B. They are used for staining of triglycerides in frozen sections, and some protein bound lipids and lipoproteins on paraffin sections. It has the appearance of reddish brown crystals and a maximum absorption at 507(304) nm.