// Workers AI · dad joke modeWhat did naphthionic acid say? I'm bonded to you.

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

Naphthionic acid is an organic compound with the formula C₁₀H₆(NH₂)(SO₃H). It is one of several aminonaphthalenesulfonic acids, which are derivatives of naphthalene containing both amine and sulfonic acid functional groups. Naphthionic acid is a white solid, although commercial samples can appear gray. Deprotonation of naphthionic acid gives the sulfonate C₁₀H₆(NH₂)(SO₃)⁻, which is call naphthionate.

Production and reactions

Naphthionic acid is prepared by treating 1-aminonaphthalene with sulfuric acid.

Naphthionic acid is used in the synthesis of azo dyes such as Rocceline (also known as Solid Red A). For this conversion sodium naphthionate is diazotated. The resulting diazonium derivative is coupled with β-naphthol.

Heating a solution of sodium naphtionate induces its conversion to 1-aminonaphthalene-2-sulfonate.