Hydrochloric Acid → 2-Chloro-4-nitroaniline

Beteiligte Stoffe

Reaktionsschritte

It has now been found that 2,6-dichloro-4-nitroaniline can be prepared in a high purity (purity of at least 96%) and a high yield (90% of theory) without the deficiencies mentioned, such as pollution of the effluent and technical effort for regeneration and working up of the effluent, by chlorination of 4-nitroaniline in water with chlorine bleaching liquor, by chlorinating 1 mole of 4-nitroaniline in 3-6 moles of hydrochloric acid (HCl) or nitric acid (HNO3) in the form of a dilute, aqueous acid in the presence of a dispersing agent which is stable under the reaction conditions, the chlorination initially being carried out at 5°-10° C. and then at 15-20° C. and, finally, after 90-95% of the 2-chloro-4-nitroaniline intermediately formed has been converted into 2,6-dichloro-4-nitroaniline, the temperature of the aqueous suspension being increased from 15°-20° C. to 70° C., without further addition of chlorine bleaching liquor and preferably with renewed addition of dispersing agent, and then by afterchlorinating, by renewed addition of chlorine bleaching liquor, at temperatures between 20° and 70° C., subsequently bringing the pH of the aqueous suspension to 9.0 and filtering off the 2,6-dichloro-4-nitroaniline formed and washing it with dilute mineral acid.

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