Method for continuous production of paranitroaniline by series-connected kettles

Abstract

The invention provides a method for continuous production of paranitroaniline by series-connected kettles. The method comprises the following steps of: adding ammonia water with mass percentage concentration of 20%-50% to two or more than two high-pressure ammonolysis kettles which are connected in series, stopping charging when ammonia water in each ammonolysis kettle accounts for 50% of the volume of the kettle, slowly starting the stirring of the ammonolysis kettle till the speed of the ammonolysis kettle rises to 200-600 r / m, then adding p-nitrchlorobenzene and ammonia water according to a molar ratio of 1: (2-10) to the first high-pressure ammonolysis kettle connected in series for carrying out continuous ammonolysis reaction when the temperature of each ammonolysis kettle is heated to 120-200 DEG C and the pressure of each ammonolysis kettle is increased to 3-9.5MPa, enabling materials reacted in the last ammonolysis kettle to enter a buffering tank for buffering, then entering a pressure relief cooling kettle for pressure relief and temperature reduction, separating the cooled materials to obtain a solid material, and drying to obtain paranitroaniline. The method has the advantages of being capable of improving the working efficiency and reducing the labor intensity and simultaneously solving the problems of unstable quality, potential safety hazards and the like caused by manual operation.

Description

technical field [0001] The invention relates to a method for continuous production of p-nitroaniline in series-connected kettles, which belongs to the category of continuous ammonolysis unit reaction in fine chemical industry. Background technique [0002] P-nitroaniline is an extremely important intermediate in the dye industry. The existing production method of p-nitroaniline is to use p-nitrochlorobenzene as raw material, and carry out high-pressure ammonolysis reaction under the condition of 33% concentrated ammonia water medium. The method of specific ammonia solution mainly contains the following two methods: [0003] The first method is to use an autoclave for intermittent ammonolysis, adding measured p-nitrochlorobenzene into the autoclave with a certain concentration (33-40%) of ammonia water, at a temperature of 170-175°C and a pressure of 4.8- Under the condition of 5.6MPa, carry out ammonolysis reaction, maintain 9-15 hours to complete the reaction, and then rec...

AI Technical Summary

Problems solved by technology

[0005] According to the deficiencies of the prior art, the present invention provides a method for continuous production of p-nitroaniline by adopting series tank type, which overcomes the control caused by unfavorable factors such as the short residence time of the pipeline reactor and the need to make the reaction temperature and pressure very high. Difficulties and insufficient yields can also change the problems of low production capacity, high energy consumption, and safety hazards caused by manual operation in single-pot batch reactions, so as to achieve the purpose of increasing production capacity, saving energy and reducing consumption.

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