92-41-1

White, crystalline solid.Soluble in water. Combustible.

ChEBI: A naphthalenesulfonic acid in which the sulfo groups are attached to positions 2 and 7 of the naphthalene ring.

The 2,7-disulfonic acid is always the main product of high-temperature sulfonation of naphthalene, but at 160 C it converts slowly to an equilibrium mixture containing ca. 30 % of the 2,6-isomer. Crystallization of the pure product from conventional sulfonation is difficult, and alternative processes, (for example, reaction of naphthalene vapor with sulfur trioxide in the gas phase at 220 C) are said to give a purer product.

Crystallise the acid from conc HCl. The disulfonamide has m 273o (from EtOH). [Beilstein 11 II 119, 11 III 463.]