Aminonaphthalenesulfonic acids

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Aminonaphthalenesulfonic acids are compounds with the composition C10H6(NH2)(SO3H), being derived from naphthalene (C10H8) substituted by an amino and sulfonic acid groups. These compounds are colorless solids. They are useful precursors to dyes.[1]

1-Aminonaphthalenesulfonic acids
Isomer CAS Registry Number Alternative names Preparative route, notes
1-Aminonaphthalene-4-sulfonic acid 84-86-6 Piria’s acid, naphthionic acid sulfonation 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 acid 84-89-9 Laurent’s acid, L acid, Purpurin acid reduction of 1-nitronaphthalene-5-sulfonic acid. With NaOH, converts to 5-amino-1-naphthol ("purpurol").
1-Aminonaphthalene-6-sulfonic acid 119-79-9 1,6-Cleve’s acid sulfonation of 1-aminonaphthalene
1-Aminonaphthalene-7-sulfonic acid 119-28-8 1,7-Cleve’s acid by-product in production of 1,6-Cleve’s acid, precursor to C.I. Acid Black 36
1-Aminonaphthalene-8-sulfonic acid 82-75-7 Peri acid reduction 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.

2-Aminonaphthalenesulfonic acids
Isomer CAS Registry Number Alternative names Preparative route and notes
2-Aminonaphthalene-1-sulfonic acid 81-16-3 Tobias acid Bucherer reaction of 2-hydroxynaphthalene-1-sulfonic acid with ammonium salts, precursor to C.I. Pigment Red 49
2-Aminonaphthalene-5-sulfonic acid 81-05-0 Dahl’s acid, Dressel acid, D acid Desulfonation of 2-aminonaphthalene-1,5-disulfonic acid
2-Aminonaphthalene-6-sulfonic acid 93-00-5 Bronner acid Bucherer amination of 2-hydroxynaphthalene-6-sulfonic acid
2-Aminonaphthalene-7-sulfonic acid 494-44-0 Amido F acid Bucherer amination of 2-hydroxynaphthalene-7-sulfonic acid
2-Aminonaphthalene-8-sulfonic acid 86-60-2 Badische acid Bucherer amination of 2-hydroxynaphthalene-8-sulfonic acid


  1. ^ Gerald Booth "Naphthalene Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a17_009.