Hoechst Aktiengesellschaft

Ernst Hille

Hartmut Heise

Emmerich Paszthory

Kurt Kummerle

Bernhard Mees

Wilfried Sahm

Reinhard Wagner

Vincenz Zimmermann

Karl-Gerhard Seifert

Wolfgang Schiller

Benzimidazolone-(2) is obtained in good yield and high purity when o-phenylene diamine is condensed with urea in water at a pH of 4 to 9 and a temperature above 90.degree. C.

Process for the preparation of benzimidazolone-(2)

The liquid-phase catalytic hydrogenation of N-acetoacetyl arylamides to yield 3-hydroxybutyric acid arylamides proceeds much faster when amines, phosphines or trialkylphosphates are added. Thus, even with lower hydrogen pressures and at lower temperatures with a lower catalyst concentration, shorter reaction times are sufficient.

Process for the manufacture of 3-hydroxybutyric acid arylamides with

5-Acetoacetylamino benzimidazolone-(2) is obtained in high yield and excellent purity by reacting diketene with the aqueous solution of a salt of 5-amino-benzimidazolone-(2) and an acid having a pKa value of 1 to 7, preferably in the presence of an antioxidant and/or a reducing agent.

Process for the preparation of 5-acetoacetylamino-benzimidazolone

The catalytic hydrogenation of 4-chloro-2,5-dimethoxy nitrobenzene can be performed in water with a nickel catalyst if the average particle size is below 0.1 mm. The resulting aniline is reacted with diketene and the so-obtained N-acetoacetyl derivative is an azoic coupling component.

Process for preparing 4-chloro-2,5-dimethoxy aniline

N-acetoacetyl-2,5-dimethoxy-4-chloroanilide is obtained in high yield and purity by suspending 2,5-dimethoxy-4-chloroaniline in water and adding the complete amount of diketene necessary altogether at the beginning of the reaction. The product is obtained in a purity allowing its use as an azoic coupling component without purification.

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Ernst Hille