Aminonaphthalenesulfonic acids


Aminonaphthalenesulfonic acids are compounds with the composition C10H6, being derived from naphthalene substituted by an amino and sulfonic acid groups. These compounds are colorless solids. They are useful precursors to dyes.
IsomerCAS Registry NumberAlternative namesPreparative route, notes
1-Aminonaphthalene-4-sulfonic acid84-86-6Piria’s acid, naphthionic acidsulfonation of 1-aminonaphthalene, precursor to acid red 25, C.I. food
red 3, C.I. food red 7, C.I. food red 9, and C.I.
1-Aminonaphthalene-5-sulfonic acid84-89-9Laurent’s acid, L acid, Purpurin acidreduction of 1-nitronaphthalene-5-sulfonic acid. With NaOH, converts to 5-amino-1-naphthol.
1-Aminonaphthalene-6-sulfonic acid119-79-91,6-Cleve’s acidsulfonation of 1-aminonaphthalene
1-Aminonaphthalene-7-sulfonic acid119-28-81,7-Cleve’s acidby-product in production of 1,6-Cleve’s acid, precursor to C.I. Acid Black 36
1-Aminonaphthalene-8-sulfonic acid82-75-7Peri acidreduction of 1-nitroonaphthalene-8-sulfonic acid, precursor to C.I. Acid Blue 113

Notes: Peri-acid dehydrates to the sultam. Via the Bucherer reaction, heating periacid with anilinium salts gives the N-phenyl derivative, precursor to Acid Blue 113.
IsomerCAS Registry NumberAlternative namesPreparative route and notes
2-Aminonaphthalene-1-sulfonic acid81-16-3Tobias acidBucherer reaction of 2-hydroxynaphthalene-1-sulfonic acid with ammonium salts, precursor to C.I. Pigment Red 49
2-Aminonaphthalene-5-sulfonic acid81-05-0Dahl’s acid, Dressel acid, D acidDesulfonation of 2-aminonaphthalene-1,5-disulfonic acid
2-Aminonaphthalene-6-sulfonic acid93-00-5Bronner acidBucherer amination of 2-hydroxynaphthalene-6-sulfonic acid
2-Aminonaphthalene-7-sulfonic acid494-44-0Amido F acid; Delta acid; Monosulphonic F acidBucherer amination of 2-hydroxynaphthalene-7-sulfonic acid
2-Aminonaphthalene-8-sulfonic acid86-60-2Badische acidBucherer amination of 2-hydroxynaphthalene-8-sulfonic acid