Trapping device and process for production of 3,4-dichlorobenzonitrile

Abstract

The invention discloses a trapping device and process for production of 3,4-dichlorobenzonitrile. The device is simple and reasonable in structural design; the implementation feasibility is high, thepracticability is high, more than 90% of ammonium chloride and more than 8% of 3,4-dichlorobenzonitrile are captured by a first-stage catcher through a dry capture method, more than 76% of 3,4-dichlorobenzonitrile is captured by a second-stage catcher through a dry capture method, latent heat of vaporization of water is fully utilized by the first-stage catcher, and the usage amount of spray liquid-water is small; besides, about 15% of the 3,4-dichlorobenzonitrile crude product collected by a third-stage catcher and a bath tower is dissolved by hot water, dehydrated, rectified and purified toobtain a liquid pure product of 3,4-dichlorobenzonitrile. The generation amount of coke oil and solid waste during the rectification process is low. Compared with a traditional multi-stage wet capturemethod, the consumption of 3,4-dichlorobenzonitrile is reduced, the investment cost of rectification equipment is reduced by more than half, the rectification energy consumption is equivalent to 15%of that of the traditional method, and the economic benefit is good.

Description

technical field [0001] The invention relates to the technical field of chemical synthesis, in particular to a trapping device and process for the production of 3,4-dichlorobenzonitrile. Background technique [0002] 3,4-Dichlorobenzonitrile (abbreviated as 3,4-DCN) is an important organic raw material for the synthesis of the selective herbicide cyhalofop; its 3,4-difluorobenzonitrile synthesized by fluorination is an important Organic fluorine pesticide intermediates; in addition, it can also be widely used as intermediates in medicine, pigments, dyes, and liquid crystal materials. [0003] As the patent protection of cyhalofop developed by Dow AgroSciences of the United States expires, research on its production method has been launched in various countries, which has led to an increasing demand for the raw material 3,4-dichlorobenzonitrile. [0004] In 3,4-dichlorobenzonitrile synthesis technology, disclosed in EP441004 by 3,4-dichloromethylbenzene and NH 4 Cl reaction ...

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Problems solved by technology

Chinese patents CN201384868Y and CN101954231B both adopt the water spray capture method. The biggest problem of this capture method is that the amount of wastewater to be treated is large, the cost of wastewater treatment is high, and it is difficult to cool down the circulating spray water

Chinese patent CN101955447B adopts the method of solvent capture, which needs to add additional organic solvents, and the energy consumption of two-stage rectification is high

At present, the domestic production of aromatics with nitrile groups and halogenated aromatics by the ammonia oxidation method is mainly thin-walled capture. This capture method is labor-intensive for workers and the working environment on site is harsh, and continuous discharge of products cannot be achieved. , a large amount of wastewater treatment

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