1-Chloro-2,4-Dinitrobenzene → Sodium 2-amino-4-nitrophenoxide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A suspension of 202.6 parts of 2,4-dinitrochlorobenzene in 300 parts of water and 7 parts of 32.6% strength sodium hydroxide solution is heated to about 90° C., and 256 parts of 32.6% strength sodium hydroxide solution are added at 90° to 95° C. in the course of about 3 hours, whilst stirring. The mixture is subsequently stirred at 90° to 95° C. for about 2 hours and 400 parts of water and 184 parts of ammonium chloride are added to the resulting 2,4-dinitrophenolate suspension, whereupon a pH value of 7.0 is established. 580 parts of a 31.9% strength hydrosulphide solution are then metered in at 70° to 75° C. in the course of about 45 minutes, whilst stirring continuously and continuously monitoring the pH value of the reduction batch, which rises to 8.6. The mixture is subsequently stirred at 70° to 75° C. for about 45 minutes. 40 parts of sodium chloride are then sprinkled in and the reaction mixture is then cooled to about 5° C. and filtered. 410 parts of a 39.6% strength aqueous press cake of sodium 2-amino-4-nitrophenolate, corresponding to 92% of the theoretical yield, are obtained. 410 parts of this press cake are introduced into 1,000 parts of water and are dissolved at pH ~1 with 225 parts of 30% strength aqueous hydrochloric acid. The sulphur is then filtered off and 116 parts of 32.6% strength sodium hydroxide solution are added to the aqueous solution of 2-amino-4-nitrophenol hydrochloride in order to establish a pH of 5. The yellow suspension of 2-amino-4-nitrophenol is subsequently stirred at 5° to 10° C. for about 1 hour and the product which has separated out is isolated by filtration. 324 parts of a 41.9% strength aqueous press cake of 2-amino-4-nitrophenol, corresponding to 135.8 parts of 100% pure 2-amino-4-nitrophenol (88% of theory, relative to 2,4-dinitrochlorobenzene) are obtained. A dried sample has a sulphur content of <0.1% and a melting point of 144° C.

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