| production method | Method 1: p-nitrochlorobenzene and aniline are used as raw materials, and the two are first condensed in the presence of copper catalyst, 4-amino diphenylamine was reduced by sodium sulfide, and the product was obtained by diazotization.. Method 2: Using diphenylamine as raw material, 4-aminodiphenylamine was reduced by nitrosation, and the product was obtained by diazotization.. In the nitrosation kettle, add 100 of chloroform and of diphenylamine (, flaky), stir and dissolve, then add of sulfuric acid, 2.5 L of 40% sodium nitrite solution was slowly added at 25-28 °c over a period of -3H. After completion of the addition, the mixture was allowed to stand for 24h to obtain a chloroform solution of N-nitrosodiphenylamine. It was transferred to a lead-lined indexing kettle, and 88kg of methanol was added at the same time, and 75kg of hydrogen chloride gas was introduced at 25-30 ° C. Within 5.5-6h to obtain a slurry of p-nitrosodiphenylamine. Transfer it to an extraction pan in which 4000L of water, 700L of 33% sodium hydroxide solution and 1000kg of ice are added in advance, the temperature is increased from 0 ℃ to 4-5 ℃, and the mixture is stirred vigorously and allowed to stand for 24h, the aqueous solution of p-nitrosodiphenylamine was separated. 30kg of silica gel were then added and mixed with it and blown with air for 5h to remove residual chloroform. The silica gel was removed by filtration and the filtrate was placed in a reduction pan. The separated chloroform layer is washed with water and dilute alkali solution, and then separated from the alkaline water layer for repeated use. An alkaline layer may also be used in the extraction pan. The aqueous solution of p-nitrosodiphenylamine and 400kg of sodium polysulfide solution were put into a reduction pot, and the temperature was increased from 30-40 °c to 80 °c within 3-4H, and kept for 1H. 4-aminodiphenylamine precipitates in a granular form. It was cooled to 30 ° C. And filtered, and the filter cake was washed 5 times with a total of 5000L of water to obtain about 270kg of product. After diazotization, salt, filtration, drying to obtain the finished product. |
