反应详情

The preparation of sodium 2,4-dinitrophenolate and the hydrosulphide reduction to give sodium 2-amino-4-nitrophenolate is carried out in accordance with the statements of Example 8. When the reduction has ended, the sulphur-containing 2-amino-4-nitrophenolate solution is added to 310 parts of 30% strength aqueous hydrochloric acid. The sulphur is filtered off from the solution of 2-amino-4-nitro-phenol hydrochloride and 8 parts of concentrated hydrosulphite (sodium dithionite) are added to the filtrate. A pH value of 3.9 is then established with 30% strength sodium hydroxide solution and the 2-amino-4-nitrophenol suspension is cooled to 0°-5° C. After filtration, 190 g of 74.8% strength 2-amino-4-nitrophenol, corresponding to 142.1 g of 100% pure 2-amino-4-nitrophenol (92% of theory, relative to 2,4-dinitrochlorobenzene) are obtained.

1. filtrationThe sulphur is filtered off from the solution of 2-amino-4-nitro-phenol hydrochloride and 8 parts of concentrated hydrosulphite (sodium dithionite)
2. additionare added to the filtrate
3. temperaturethe 2-amino-4-nitrophenol suspension is cooled to 0°-5° C
4. filtrationAfter filtration, 190 g of 74.8% strength 2-amino-4-nitrophenol