Acid red 88

Acid red 88 is an azo dye. Due to its intense colour, solid samples appear almost black. It is used to dye cotton textiles red.^[1] A closely related acid dye is Acid Red 13.

Acid red 88

Names
IUPAC name Sodium 4-(2-hydroxy-1-naphthalenylazo)-naphthalenesulfonate
Other names Fast Red A 2-Naphthol Red Roccelline Solid Red A Toyo roccelline
Identifiers
CAS Number	1658-56-6 (E)-diazen Y
3D model (JSmol)	Interactive image
ChemSpider	23621588 N
ECHA InfoCard	100.015.238
EC Number	216-760-3
MeSH	Fast+red+S
PubChem CID	23722700 23669381 (Z)-diazen 23670762 (E)-diazen
RTECS number	QK2420000
UNII	7Z2135Z4K4 (E)-diazen Y
CompTox Dashboard (EPA)	DTXSID1041714
InChI InChI=1S/C20H14N2O4S.Na/c23-18-11-9-13-5-1-2-6-14(13)20(18)22-21-17-10-12-19(27(24,25)26)16-8-4-3-7-15(16)17;/h1-12,20H,(H,24,25,26);/q;+1/p-1 N Key: IVEHGZAIVWEKHA-UHFFFAOYSA-N N
SMILES [Na+].O=S(=O)([O-])c3ccc(N=Nc1c(O)ccc2ccccc12)c4ccccc34
Properties
Chemical formula	C20H13N2NaO4S
Molar mass	400.38 g·mol−1
Appearance	Vivid, dark red, opaque, vitreous solid
Melting point	280 °C (536 °F; 553 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Preparation and use

It can be obtained by azo coupling of naphthionic acid and 2-naphthol. Instead of crystallising, it vitrifies when cooled or salted out of the solution.

This compound is used in the textile industry as a dye.^[2] It can also be used for research in photocatalysis (as degradation object).^[3]