Ciba-geigy Ag

Fred Von Kaenel

Eric Plattner

Sebastian Staubli

Hans Thies

The invention relates to an improved process for the production of 2-amino-1-naphthalenesulfonic acid (Tobias acid). This improved process makes it possible to obtain Tobias acid which has only a very low content of 2-aminonaphthalene and in high space-time yield. The process starts from 2-hydroxynaphthalene and comprises the following main reaction steps:

Process for the production of 2-amino-1-naphthalenesulfonic acid

A process for the production of an aryl thiol, which comprises hydrogenating an aryl sulfochloride in a protic or aprotic solvent in the presence of platinum as catalyst, at a temperature between 100.degree. and 180.degree. C., with hydrogen under a pressure of 2 to 140 bar, in a single reaction step.

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Seltisberg, Switzerland

Fred Von Kaenel