120-18-3

Nondeliquescent, white plates.Soluble in water, alcohol, and ether. Combustible.

ChEBI: A naphthalenesulfonic acid in which the sulfo group is linked to position 2 of the naphthalene ring.

Naphthalene-2-sulfonic acid is prepared by sulfonation of naphthalene.
Step: With naphthalene as raw material, 98% sulfuric acid is used as sulfonating agent, and it is obtained by sulfonation at 160-166 ℃. During the sulfonation process, a small amount of α-naphthalenesulfonic acid by-product is generated. By heating, the unstable α-naphthalenesulfonic acid can be hydrolyzed at 140-150 °C to remove the sulfonic acid group, and become naphthalene and sulfuric acid. Naphthalene can be blown out. During the hydrolysis of naphthalene, a small amount of lye should be added to neutralize part of the sulfuric acid. It also acts with naphthalenesulfonic acid to form β-naphthalenesulfonic acid sodium salt crystals, which can be filtered to obtain the finished product of Naphthalene-2-sulfonic acid.

Nonflammable

Crystallise the acid from conc HCl. The S-benzylisothiuronium salt has m 192o (from aqueous EtOH). [Berger Acta Chem Scand 8 432 1954, Beilstein 11 H 171, 11 IV 527.]