Naphthalenedisulfonic acid

Naphthalenedisulfonic acid refers to organic compounds with the formula C10H6(SO3H)2. They are derivatives of naphthalene. Twelve isomers are possible, but only a few have been examined in some depth, often as precursors to azo dyes or to various drugs. They are colorless solids with high solubility in water. Some derivatives are prepared by sulfonation of naphthalene or its monosulfonic acids. A few are produced by indirect routes.

Hydroxynaphthalenesulfonic acids
name Registry number m.p., °C prep Precursor to
1,3-Naphthalenedisulfonic acid 6094-26-4 250 deamination 2-aminonaphthalene-6,8-disulfonic acid obscure
1,5-Naphthalenedisulfonic acid, Armstrong acid 81-04-9 240-245 sulfonation of naphthalene with oleum (together with 1,6-isomer) 1-hydroxynaphthalene-5-sulfonic acid, 1,5-dihydroxynaphthalene, 1,3,5-naphthalenetrisulfonic acid
1,6-Naphthalenedisulfonic acid 525-37-1 125 sulfonation of naphthalene with oleum (together with 1,5-isomer) 1,6-dihydroxynaphthalene, 1,3,6-naphthalenetrisulfonic acid
1,7-Naphthalenedisulfonic acid 5724-16-3 ? low T sulfonation of naphthalene-2-sulfonic acid in low yields obscure
2,6-Naphthalenedisulfonic acid 581-75-9 ? high T sulfonation of naphthalene 2-hydroxynaphthalene-6-sulfonic acid and 2,6-dihydroxynaphthalene
2,7-Naphthalenedisulfonic acid 92-41-12 ? high T sulfonation of naphthalene 2-hydroxynaphthalene-7-sulfonic acid, 2,7-dihydroxynaphthalene

In addition to these compounds, several naphthalenetrisulfonic acids are known as well as several hydroxy derivatives.

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