Naphthalene-1-sulfonic 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. The ...

with the formula C₁₀H₇SO₃H. A colorless, water-soluble solid, it is often available as the

dihydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

C₁₀H₇SO₃H^.2H₂O. It is one of two mono

sulfonic acid In organic chemistry, sulfonic acid (or sulphonic acid) refers to a member of the class of organosulfur compounds with the general formula , where R is an organic alkyl or aryl group and the group a sulfonyl hydroxide. As a substituent, it is kn ...

s 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 aromati ...

, the other being the more stable naphthalene-2-sulfonic acid. The compound is mainly used in the production of dyes.{{cite encyclopedia, authors=Gerald Booth, title=Naphthalene Derivatives, encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry, year=2005, publisher=Wiley-VCH, location=Weinheim, doi=10.1002/14356007.a17_009, isbn=3527306730 Naphthalene-1-sulfonic acid undergoes many reactions, some of which are or were of commercial interest. Upon heating with dilute aqueous acid, it reverts to naphthalene. Fusion with sodium hydroxide followed by acidification gives 1-naphthol. Further sulfonation gives 1,5-naphthalene-disulfonic acid. Reduction with

triphenylphosphine Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to P Ph3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists a ...

gives 1-naphthalenethiol.

References

Naphthalenesulfonic acids 1-Naphthyl compounds