Phosgene → 3-Chloroisatoic anhydride

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

190.7 g of 90% 3-chloroanthranilic acid, corresponding to 171.6 g (1.0 mol) of 100% 3-chloroanthranilic acid, are initially introduced, in 1,970.0 g of chlorobenzene, into a four-necked flask having a stirrer, a thermometer and a reflux condenser cooled down to -20° C., and 300.0 g of phosgene are then metered in at room temperature over a period of about 3 h while stirring thoroughly. The reaction mixture is heated to 100° C. and a further 150.0 g of phosgene are passed in over a period of 2 h. After that, the mixture is stirred at 100° C. for a further 1 h, and the phosgene is subsequently removed 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. 190.0 g of 3-chloroisatoic anhydride, having a purity by GC of >99%, are obtained, corresponding to 96.2% of theory. In that which follows, m.p. stands for melting point, s.p. for solidification point and MS for mass spectrum.

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