Phosgene → 3-Chloroisatoic anhydride

Participants

Reaction Conditions

Reaction Steps

171.6 g (1.0 mol) of 99.7% 3-chloroanthranilic acid are initially introduced, in 1,720.0 g of chlorobenzene, into a four-necked flask having a stirrer, a thermometer and a reflux condenser operated at -20° C., and 440.0 g of phosgene are gassed in at 100° C. over a period of about 3 h while stirring thoroughly. After that, the mixture is stirred at 100° C. for a further 1 h, and is subsequently blown free of phosgene at this temperature using nitrogen. After cooling to about 25° C., the crystals which have precipitated out are filtered off with suction and the filter cake is washed with 2×50 ml of chlorobenzene and dried at 100° C. in vacuo. 184.9 g of 3-chloroisatoic anhydride, having a purity by GC of >99%, are obtained, corresponding to 93.6% of theory.

Provenance & Evidence