Process for the preparation of halogen-thiophene-2-carboxylic acids

Die Erfindung betrifft ein Verfahren zur Herstellung von Halogenthiophen-2-carbonsäuren der allgemeinen Formel durch Oxidation der entsprechenden Halogen-2-acylthiophene der allgemeinen Formel Die Oxidation wird mittels Sauerstoff in einem Lösungsmittel in Gegenwart eines Katalysators durchgeführt. 1. A process for the preparation of halothiophene-2-carboxylic acids of the general formula see diagramm : EP0216279,P4,F1 in which Hal denotes halogen and n denotes 1 or 2, by oxidation of the appropriate halo-2-acylthiophenes of the general formula see diagramm : EP0216279,P4,F2 where x = 0 to 3, which comprises carrying out the oxidation in an aliphatic carboxylic acid having up to five carbon atoms, in particular acetic acid as the solvent, in the presence of Mn, Co, Cr or Fe in the form of salts, either alone or mixed with each other, as the catalyst, using oxygen at a reaction temperature of 50 to 200 degrees C.