Novel process for synthesizing 2-cyano-4-nitrochlorobenzene through continuous nitration by solvent method

Abstract

The invention provides a novel process for synthesizing 2-cyano-4-nitrochlorobenzene through continuous nitration by a solvent method. The process comprises the following steps of: 1, preparation of a benzonitrile solution: dissolving o-chlorobenzonitrile by using an organic solvent to prepare a benzonitrilesolution for later use; 2, preparation of a mixed acid nitrating agent; 3, nitration reaction: respectively pumping the benzonitrile solution in the step 1 and the mixed acid nitrating agent in the step 2 into a nitration reactor, and carrying out nitration reaction to generate a nitration liquid; 4, phase-splitting treatment: mixing the nitration liquid in the step 3 with water, adding a secondary solvent, uniformly mixing, and carrying out phase-splitting treatment; and 5, recovery of an the organic solvent: carrying out evaporation treatment on 2-cyano-4-nitro-chlorobenzene solution in the step 4, wherein the evaporation residue is a 2-cyano-4-nitro-chlorobenzene product.According to the method, an organic solvent is used for replacing sulfuric acid to dissolve o-chlorobenzonitrile, so that the amount of waste acid generated in the reaction process is greatly reduced; and by adopting a continuous nitration reaction, the safety risk level is reduced, and the product yield is improved.

Description

technical field [0001] The invention belongs to the technical field of chemical production, and in particular relates to a new process for synthesizing 2-cyano-4-nitrochlorobenzene by continuous nitration by solvent method. Background technique [0002] 2-cyano-4-nitro-aniline is an important intermediate of disperse dyes, and its synthesis process starts with o-chlorobenzonitrile 2-cyano-4-nitro-chlorinated benzene is generated for the nitration reaction of raw materials, and then 2-cyano-4-nitro-aniline is obtained through ammonolysis reaction. In the nitration reaction of o-chlorobenzonitrile, 98% About concentrated sulfuric acid is used as solvent acid to dissolve o-chlorobenzonitrile, and about 98% of concentrated sulfuric acid and about 98% of concentrated nitric acid are used to make a mixed acid nitrating agent, which is nitrated at a low temperature below 10°C, and 2-cyano-4- Nitrochlorobenzene. This process has two major disadvantages: 1. The amount of waste aci...

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Problems solved by technology

This process has two major disadvantages: 1. The amount of waste acid produced is large. Every ton of 2-cyano-4-nitro-chlorinated benzene product produces 10 tons of 40% waste acid. This waste acid not only pollutes the environment, but also costs High, the cost of waste acid treatment accounts for 25% of the total cost of 2-cyano-4-nitrochlorobenzene products; 2. The nitration reaction is an exothermic reaction with a fast reaction rate, and poor temperature control will not only generate many nitro By-products such as substances and oxidation affect the conversion rate, and are likely to cause safety issues such as explosions

Therefore, intermittent nitration reaction is adopted, and there are many reaction materials, so it is not conducive to temperature control, and the safety risk is relatively large.

[0003] Chinese patent 2-cyano-4-nitroaniline new process for separation of nitrates in the production (application number: 201610251355.7), the patent uses the traditional process for nitration reaction, after the nitration reaction, the product is extracted to separate the product from the acid solution, Acid solution reuse. Although the patent can realize acid solution reuse, it still uses the traditional nitration reaction. On the one hand, continuous reaction cannot be realized, and the safety risk level is still high. On the other hand, sulfuric acid is still used to dissolve o-chlorobenzonitrile, and The introduction of water into the system reduces the acid concentration, and a large amount of acid still needs to be replenished in the process of acid reuse, so the reduction of acid is limited

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