Bayer Aktiengesellschaft

Helmut Lahr

Franz-Josef Mais

Helmut Fiege

Michael Pies

Kai Rohlk

Disclosed herein is a method for producing 2,3,4,5-tetrachlorobenzotrifluoride comprising chlorinating 4-chlorobenzotrifluoride with elemental chlorine, in the presence of from 0.1 to 2% by weight of iron(III) chloride and 0.05 to 0.75% by weight of aluminum(III) chloride, in each case based on 4-chlorobenzotrifluoride, where the weight ratio of iron(III) chloride to aluminum(III) chloride is 10:1 to 1:1.

Method for producing 2,3,4,5-tetrachlorobenzotrifluoride

A process for preparing 2-chloro-4-nitroalkylbenzenes is provided which comprises a ring chlorination of 4-nitroalkylbenzenes with elemental chlorine or chlorine-releasing compounds in liquid phase and in the presence of Friedel-Crafts catalysts and specific sulphur-containing aromatic compounds as co-catalysts.

Process for preparing 2-chloro-4-nitroalkylbenzene

In a particularly advantageous process for isolating m-dichlorobenzene from mixtures of dichlorobenzene isomers by crystallization as eutectic crystals using a processing aid, the processing aid used is a compound of the formula (I) ##STR1## in which R.sup.1 to R.sup.6 are, independently of one another, hydrogen, halogen, C.sub.1 -C.sub.4 -alkyl, hydroxyl, NH.sub.2 or R--CO-- having R=C.sub.1 -C.sub.4 -alkyl, with 1-bromo-4-chlorobenzene and 1,4-dibromobenzene being excepted.

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Odenthal, Germany

Helmut Lahr