Process for the preparation of 5-amino-2,4-dimethylacetanilide
AssigneeBayer Aktiengesellschaft
InventorsHorst Behre, Heinz U. Blank, Alfred Seyberlich, Ferdinand Hagedorn
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Abstract
A process for the preparation of 5-amino-2,4-dimethylacetanilide by reduction of 5-nitro-2,4-dimethylacetanilide with hydrogen is disclosed characterized in that a crude mixture containing 5-nitro-2,4-dimethylacetanilide in admixture with at least one of its position isomers is hydrogenated in a water-miscible organic solvent which optionally contains water. The 5-amino-2,4-dimethylacetanilide is separated off from the reaction mixture by means of crystallization employing a mixture of water-miscible organic solvent and water.
Claims15
A process for the preparation of 5-amino-2,4-dimethylacetanilide which comprises contacting 5-nitro-2,4-dimethylacetanilide in the form of a mixture containing 70 to 94.9% by weight of 5-nitro-2,4-dimethylacetanilide, 5 to 20% by weight of 3-nitro-2,4-dimethylacetanilide and 0.1 to 10% by weight of 6-nitro-2,4-dimethylacetanilide, relative to the sum of said compounds with hydrogen in the presence of a hydrogenation catalyst under hydrogenation conditions in a mixture of water and an alkanol wherein these solvents are present in a 100:1 to 1:100 weight ratio, separating off the hydrogenation catalysts and separating 5-amino-2,4-dimethylacetanilide from a mixture of alkanol and water by means of crystallization.
A process according to 1, wherein said alkanol is methanol.
A process for the preparation of 5-amino-2,4-dimethylacetanilide which comprises:
- (A) contacting 2,4-dimethylaniline with nitric acid in concentrated sulphuric acid under nitration conditions whereby to form the corresponding 5-nitro compound in a mixture with at lest one of the corresponding 3-nitro and 6-nitro compounds;
- (B) contacting the mixture of nitro-2,4-dimethylanilide obtained from step A with an acetylating agent whereby to form a mixture of 5-nitro-2,4-dimethylacetanilide containing 70 to 94.9% by weight of 5-nitro-2,4-dimethylacetanilide, 5 to 20% by weight of 3-nitro-2,4-dimethylacetanilide and 0.1 to 10% by weight of 6-nitro-2,4-dimethylacetanilide, relative to the sum of said compounds;
- and
- (C) contacting the mixture of nitro-2,4-dimethylacetanilides of step B with hydrogen in the presence of a hydrogenation catalyst under hydrogenation conditions in a mixture of water and an alkanol, separating off the hydrogenated catalyst and separating 5-amino-2,4-dimethylacetanilide from a mixture of alkanol and water by means of crystallization.
Dependencies are inferred from the claim text.