Bayer Aktiengesellschaft

Rolf Schimpf

Heinz U Blank

Herbert Emde

Walter Horstmann

Gerhard Stopp

The present invention relates to an improved preparation process for 2-aminobenzene-1,4-disulphonic acids and the new compound 6-chloro-2-aminobenzene-1,4-disulphonic acid.

Process for the preparation of 2-aminobenzene-1,4-disulphonic acids and

P-Toluidine-2-sulphonic acid (5-amino-2-methylbenzenesulphonic acid) is obtained in very pure form and virtually free of p-toluidine-3-sulphonic acid (2-amino-5-methylbenzenesulphonic acid) by reacting p-toluidine at 10.degree.-55.degree. C. with oleum in sulphuric acid. The molar ratio of SO.sub.3 to p-toluidine in this reaction is 1-3.0:1. The reaction mixture is worked up by pouring into water and filtering off the precipitated p-toluidine-2-sulphonic acid.

Process for preparing p-toluidine-2-sulphonic acid

A process for the preparation of 2-methoxy-5-methylaniline-4-sulphonic acid by contacting optionally acylated 2-methoxy-5-methylaniline with sulfuric acid or a mixture of sulfuric acid and oleum at an elevated temperature.

Process for the preparation of 2-methoxy-5-methylaniline-4-sulphonic acid

2-Nitro-4-acetylamino-anisole is prepared directly in the form of a moist, free-flowing material by nitrating 4-acetylamino-anisole and then treating the reaction mixture with water at slightly elevated temperatures, e.g., 20-60.degree. C.

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Leverkusen, Germany

Rolf Schimpf