Naphthionic acid is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon- hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

with the formula C₁₀H₆(SO₃H)(NH₂). It is one of several

aminonaphthalenesulfonic acid Aminonaphthalenesulfonic acids are compounds with the composition C10H6(NH2)(SO3H), being derived from naphthalene (C10H8) substituted by an amino and sulfonic acid In organic chemistry, sulfonic acid (or sulphonic acid) refers to a member of th ...

s, derivatives of

naphthalene Naphthalene is an organic compound with formula . It is the simplest polycyclic aromatic hydrocarbon, and is a white crystalline solid with a characteristic odor that is detectable at concentrations as low as 0.08 ppm by mass. As an aromat ...

containing both

amine In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent su ...

and sulfonic acid functional groups. It is a white solid, although commercial samples can appear gray.''4-Amino-1-naphthalenesulfonic acid;'' MSDS No. 250619; Sigma–Aldrich Chemie GmbH: Steinheim, 29 Dec 2011. It is used in the synthesis of

azo dyes Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C-N=N ...

such as Rocceline (a. k. a. Solid Red A), during which the

amino group In chemistry, amines (, ) are compounds and functional groups that contain a basic nitrogen atom with a lone pair. Amines are formally derivatives of ammonia (), wherein one or more hydrogen atoms have been replaced by a substituent such ...

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 1-Naphthylamine is an aromatic amine derived from naphthalene. It can cause bladder cancer (transitional cell carcinoma). It crystallizes in colorless needles which melt at 50 °C. It possesses a disagreeable odor, sublimes readily, and tu ...

with sulfuric acid.Gerald Booth "Naphthalene Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. .

References

Naphthylamines Naphthalenesulfonic acids {{Aromatic-stub