Naphthalene-2-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 mono- and trihydrates 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 naphthalene-1-sulfonic acid. The compound is mainly used in the production of dyes via nitration en route to

aminonaphthalenesulfonic acids Aminonaphthalenesulfonic acids are compounds with the composition C10H6(NH2)(SO3H), being derived from naphthalene (C10H8) substituted by an amino and sulfonic acid groups. These compounds are colorless solids. They are useful precursors to dyes ...

. The compound is prepared by

sulfonation Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution. Aryl sulfonic acids are used as detergents, dye, and drugs. Stoichiometry an ...

of naphthalene with sulfuric acid, however under equilibrating conditions that allow the 1-sulfonic acid isomer to convert to the more stable 2-sulfonic acid.{{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-2-sulfonic acid undergoes many reactions, some of which are or were of commercial interest. Fusion with sodium hydroxide followed by acidification gives 2-naphthol. It is an intermediate in the formation of 2,6-, 2,7- and 1,6-naphthalene disulfonic acids as well as 1,3,6-naphthalenetrisulfonic acid. Naphthalene-2-sulfonic acid condenses with

formaldehyde Formaldehyde ( , ) (systematic name methanal) is a naturally occurring organic compound with the formula and structure . The pure compound is a pungent, colourless gas that polymerises spontaneously into paraformaldehyde (refer to section F ...

to give polymeric sulfonic acids.

References

Naphthalenesulfonic acids 2-Naphthyl compounds