反应详情

温度

15 °C

202.6 parts of 2,4-dinitrochlorobenzene are converted into sodium 2,4-dinitrophenolate in accordance with the statements in Example 1 and, after adding 400 parts of water and 184 parts of ammonium chloride, the pH value is adjusted to 7.0. Reduction to sodium 2-amino-4-nitrophenolate is carried out with 580 parts of 31.9% strength hydrosulphide solution at pH values of at most 9, whilst stirring and monitoring the pH. After addition of the hydrosulphide, the mixture is subsequently stirred at 70° to 75° C. for about 45 minutes and the sulphur which has precipitated is filtered off. 100 g of sodium sulphite are added to the filtrate and the mixture is cooled to about 15° C. and adjusted to a pH of 5.6 to 5.8 with 136 parts of 30% strength hydrochloric acid. The mixture is subsequently stirred for about a further hour at 5° to 10° C. and filtered and the filter cake is rinsed with about 200 parts of 26% strength aqueous sodium chloride solution. 277.6 parts of a 53.3% strength aqueous press cake of 2-amino-4-nitrophenol, corresponding to 147.9 parts of 100% pure 2-amino-4-nitrophenol (96% of theory, relative to 2,4-dinitrochlorobenzene) are obtained. The product has a sulphur content of <0.1% and a melting point of 144° C.

1. stirringthe mixture is subsequently stirred at 70° to 75° C. for about 45 minutes
2. customthe sulphur which has precipitated
3. filtrationis filtered off
4. addition100 g of sodium sulphite are added to the filtrate
5. stirringThe mixture is subsequently stirred for about a further hour at 5° to 10° C.
6. filtrationfiltered
7. washthe filter cake is rinsed with about 200 parts of 26% strength aqueous sodium chloride solution