Method for preparing ortho-nitroaniline by kettle-type continuous operation

Abstract

The invention relates to a method for preparing ortho-nitroaniline by kettle-type continuous operation, belonging to the organic chemical engineering field; pressure-resistant reaction kettles are sequentially connected in series, and high-order differences are formed among the reaction kettles, so as to lead the reaction material to overflow to the next-level reaction kettle; 0-nitrophenyl and ammonia water are added in a first-level reaction kettle in the pressure-resistant reaction kettle, and the mixture is reacted under the condition that the temperature in the kettle is 150 DEG C to 250 DEG C, and pressure is 3MPa to 10MPa, and then the reacted products are oil-water laminated; after water is cooled, the ortho-nitroaniline is dissolved out in a solid way and is press-filtered into filter cakes, namely, the ortho-nitroaniline is obtained. The method has simple flow, stable yield coefficient of products and less three wastes, and is easy to realize industrialization.

Description

technical field [0001] The invention belongs to the field of organic chemical industry and relates to a production method for preparing o-nitrochlorobenzene from o-nitrochlorobenzene. Background technique [0002] O-nitroaniline is an important intermediate in organic synthesis. It is an intermediate for many pesticides, medicines and dyes, and it is also widely used in the field of auxiliaries. At present, the synthesis of o-nitroaniline mainly adopts the ammonolysis process of o-nitrochloroaniline, and there are mainly two processes of continuous high-pressure pipeline and intermittent autoclave. About the process of carrying out nitrobenzene aminolysis in high-pressure pipelines, there were US patents published in the 1930s, such as US1877145 and US1884880. From 1937 to 1938, Germany also carried out more detailed research on the ammonolysis process of nitrochlorobenzene in high-pressure pipelines and carried out pilot tests. In the 1970s in my country, Shanghai Dyestuf...

AI Technical Summary

Problems solved by technology

Although the high-pressure pipeline continuous production process has the advantages of simple equipment structure, easy operation, and large production capacity, due to the high temperature and pressure in the production process, there are many side reactions, such as the hydrolysis of o-nitrochlorobenzene, o-nitroaniline molecules Internal dehydration, etc., thereby generating impurities such as o-nitrophenol and benzofurazan, resulting in low product purity and yield, because the molar ratio of o-nitrochlorobenzene and ammonia in this process is high, which also increases the waste water. Handling Difficulty

Although the autoclave batch process is simple, it has the disadvantages of small production capacity and high operating intensity.

In addition, the kettle-type intermittent washing used in the above process cannot completely wash away the ammonium chloride in o-nitroaniline due to the limited number of washings, thus affecting its application in pesticides, medicines, etc., and the washing process requires more washing water , which also produces a large amount of wastewater