Phosgene → 3-Chloroisatoic anhydride

Temperatur

-20 °C

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.

1. temperatureThe reaction mixture is heated to 100° C.
2. customare passed in over a period of 2 h
3. stirringAfter that, the mixture is stirred at 100° C. for a further 1 h
4. customthe phosgene is subsequently removed at this temperature
5. temperatureAfter cooling to about 25° C.
6. customthe crystals which have precipitated out
7. filtrationare filtered off with suction
8. washthe filter cake is washed with 2×50 ml of chlorobenzene
9. customdried at 100° C. in vacuo
10. customare obtained, corresponding to 96.2% of theory

ORD-Eintrag

ord-c9f9a355ceaf45e38e3ed110e6504968

Quelldatensatz

uspto-grants-1996_09

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05557005