Naphthionic acid

Naphthionic acid
Names
	Preferred IUPAC name 4-Aminonaphthalene-1-sulfonic acid
	Other names Piria's acid
Identifiers
CAS Number	84-86-6 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:38219;
ChemSpider	6532;
ECHA InfoCard	100.001.425
EC Number	201-567-9;
PubChem CID	6790;
UNII	8ZIK65C5CD ;
CompTox Dashboard (EPA)	DTXSID3058909 ;
	InChI InChI=1S/C10H9NO3S/c11-9-5-6-10(15(12,13)14)8-4-2-1-3-7(8)9/h1-6H,11H2,(H,12,13,14) Key: NRZRRZAVMCAKEP-UHFFFAOYSA-N; InChI=1/C10H9NO3S/c11-9-5-6-10(15(12,13)14)8-4-2-1-3-7(8)9/h1-6H,11H2,(H,12,13,14) Key: NRZRRZAVMCAKEP-UHFFFAOYAN;
	SMILES c1ccc2c(c1)c(ccc2S(=O)(=O)O)N;
Properties
Chemical formula	C10H9NO3S
Molar mass	223.24
Appearance	white solid
Density	1.6703 g/cm3
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Naphthionic acid is an organic compound with the formula C₁₀H₆(SO₃H)(NH₂). It is one of several aminonaphthalenesulfonic acids, derivatives of naphthalene containing both amine and sulfonic acid functional groups. It is a white solid, although commercial samples can appear gray. It is used in the synthesis of azo dyes such as Rocceline (a. k. a. Solid Red A), during which the amino group of the acid (in the form of a salt) is diazotated and then coupled with, in the case mentioned, β-naphthol. It is prepared by treating 1-aminonaphthalene with sulfuric acid.