5-Amino-1-naphthalenesulfonic acid

?1-Aminonaphthalene-5-sulfonic acid [84- 89-9]. (5-aminonaphthalene-1-sulfonic acid), Laurent’s acid, L acid, Purpurin acid, C10H9NO3S, Mr 223.24, crystallizes from hot water as needles of the monohydrate. The alkalimetal salts are all readily soluble in water. Bromination yields the 2,4-dibromo derivative, vigorous nitration gives 2,4-dinitro-1- hydroxynaphthalene, and sulfonation results in 1-aminonaphthalene-2,5,7-trisulfonic acid. 1- Hydroxynaphthalene-5-sulfonic acid is obtained by heating 104 with aqueous bisulfite (reverseBucherer reaction) or via the diazo compound. Caustic fusion produces 5-amino-1-hydroxynaphthalene. Coupling with diazo compounds takes place in the 2-position.

5-Aminonaphthalene-1-sulfonic acid is an deriva- tizing agents in the precolumn derivatization of some chiral phenoxy acid. Cu(II) based on a dansyl derivative was synthesized with 29.2% overall yield by a seven-step synthetic procedure from the readily available starting material 5-aminonaphthalene-1-sulfonic acid.

Intermediate of dyestuff

ChEBI: 5-Amino-1-naphthalenesulfonic acid is a naphthalenesulfonic acid.

Laurent’s acid is coproduced with Peri acid as the minor component of a 5:2 isolated product ratio.

Crystallise the acid under nitrogen from boiling water and dry it in a steam oven [Bryson Trans Faraday Soc 47 522, 527 1951]. [Beilstein 14 IV 2800.]