Bayer Aktiengesellschaft

Kramer Aktiengesellschaft

Otto Lindner

Heinz U Blank

Horst Behre

Guido Steffan

Erich Hammerschmidt

Arnd Stuwe

Willi Schossler

Heinrich Pelster

Gerhard Burmeister

The invention concerns new sulfonation products of naphthalene, process for their preparation according to which naphthalene is sulfonated under special reaction conditions by sulfur trioxide in inert organic solvents. The new sulfonation products are used as intermediates e.g. for the production of naphthalene-1,5-disulfonic acid.

Sulphonation products of naphthalene, processes for their preparation,

Improved process for the preparation of nitronaphthalene-sulphonic acids by reacting the corresponding naphthalene-sulphonic acids with nitric acid and working up the nitration mixture, characterized by the features that the reaction of the naphthalene-sulphonic acids with nitric acid is already interrupted before the nitration reaction has ended and that the nitration mixture is treated, optionally after dilution with water, with bases at a pH value of 5 to 14.

Process for the preparation of nitronaphthalene-sulphonic acids

The process for preparing 1-amino-2-naphthol-4-sulphonic acid by acidifying 3-oxo-4-hydroxyimino-1,2,3,4-tetrahydronaphthalene-1-sulphonic acid or its alkali metal salt in the presence of hydrogen sulphite is carried out in the presence of iron ions.

Process for preparing 1-amino-2-naphthol-4-sulphonic acid (amidol acid)

The invention relates to a process for isolating H acid and K acid in the form of their monoalkali metal salts from acid aqueous solutions which contain these two acids and alkali metal ions and may contain other aminonaphtholdisulphonic acids, in which process H acid monoalkali metal salts are precipitated at elevated temperatures from solutions which contain not only sodium ions but also potassium ions and then precipitating K acid monoalkali metal salts by cooling down the filtrate obtained after separating off the H acid monoalkali metal salts.

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Bergisch-Gladbach, Germany

Otto Lindner