Process for the preparation of certain ring-chlorinated benzotrichlorides

3,4-Dichlorobenzotrichloride, 3,4,5-trichlorobenzotrichloride, 2,4,5-trichlorobenzotrichloride and/or 2,3,4,5-tetrachlorobenzotrichloride are obtained by reacting p-chlorobenzotrichloride of the formula I, with chlorine or with a chlorine-releasing agent in the presence of iron(III) chloride or aluminium chloride or of a mixture of iron(III) chloride or aluminium chloride with sulphur dichloride or disulphur dichloride as catalyst at temperatures between 0 DEG C and 180 DEG C. The ring-chlorinated benzotrichlorides which can be prepared according to the invention can be used as plasticisers for plastics or else as solvents. Furthermore, these ring-chlorinated benzotrichlorides can be converted into the corresponding benzoic acids, for example by hydrolysis of the trichloromethyl group, and these benzoic acids are suitable for the synthesis of colorants. Furthermore, the compounds which are accessible according to the invention are, for example, valuable starting substances for the preparation of substituted diphenyl ethers which have an outstanding herbicidal activity.