Naphthionic acid

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.^[1] 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.^[2]

Naphthionic acid

Names
Preferred IUPAC name 4-Aminonaphthalene-1-sulfonic acid
Other names Piria's acid
Identifiers
CAS Number	84-86-6 Y
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 Y
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