which n has the meaning given and r each independently represents c 1 6 alkyl or c 1 6 alkoxy and under friedel crafts acylation conditions by adding a lewis acid and the corresponding substituted benzene derivative preferably of formula iv str6 in particular 1 2 dimethoxybenzene 3 4 5 trimethoxytoluene or 3 4 dimethoxy 5 butoxytoluene to said reaction mixture it is also possible to purify the obtained chloro benzoylchlorides using standard procedures as for example crystallization or distillation in particular by distillation under reduced pressure in particular at pressures between 1 and 100 mbar the novel process enables to carry out the production of chloro benzoyl chlorides in technical scale and high yields using cheap ready available educts in order to facilitate a further understanding of the invention the following illustrative examples are presented the invention is not limited to the specific embodiments described or illustrated but encompasses the full scope of the appended claims a mixture of 115 g 4 chlorobenzotrichloride cbtc 0 5 mol and 1 6 g fecl 3 10 mmol is heated to 60 u00b0 c 9 g water 0 5 mol are dosed into the mixture within 1 hours at ambient pressure after 30 minutes the reaction was complete the gc analysis showed that the conversion was complete 98 area pcbo.