Process for the separation of gaseous mix products in chloro-pyridine compounds production

Abstract

The present invention relates to a separation method of gaseous mixture in the preparation of chlorinated pyridine compounds. Pyridine and derivatives are used as raw materials and react with a chlorating agent in a reactor to prepare the gaseous products of the category of chlorinated pyridine. Under the condition with nitrogen, the gaseous products directly enter at least two distillation units that are connected orderly to realize online distillation and purification; the distillation units respectively comprise a distillation system that consists of a distillation reactor and a distillation tower. The operating temperature of each distillation unit that is arranged orderly is respectively lower than the boiling point of the collected distillate but higher than the boiling point of the adjacent distillate; the distillation unit that are arranged orderly are respectively used for collecting the corresponding distillates with the boiling points decreasing orderly. The operation is simple; the separation and the reaction can operate simultaneously, thus shortening the total time of the process; the target compound with high content can be prepared at one time. And the separation method has the advantages of low coking rate of the product, less loss, low energy consumption, small occupied space, high utilization rate, high operation safety, and suitability for the industrial production.

Description

technical field [0001] The invention relates to a separation method for preparing corresponding pyridine chlorination products by using pyridine or its derivatives as raw materials, specifically an on-line continuous preparation method for directly separating the gaseous mixture obtained after synthesis by rectification Separation method. Background technique [0002] Chlorine-containing derivatives of pyridine, such as chlorinated pyridine with different substitution positions and / or substitution quantities, pyridine derivatives substituted with different positions and / or quantities of chlorine and cyano groups, etc., are important chemical intermediates, used in pesticides and It can be widely used in pharmaceutical synthesis and other aspects. For example, 3,4,5,6-tetrachloro-2-cyanopyridine can be used to synthesize pesticides such as high-efficiency herbicide Bikecao and picloram; 2,3,5-trichloropyridine can be used to synthesize oxafefen, Pesticides such as insects a...

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Problems solved by technology

In addition, because the material is easily in contact with the operator's body during the transfer process, it is not conducive to occupational health and safety; again, this method consumes a lot of energy and costs high, and because it is easy to wrap chlorinated agents such as hydrogen chloride in the cooling and crystallization process Therefore, before distillation or rectification, pretreatment including deacidification is required, and a large amount of three wastes will be generated, which is not conducive to environmental protection. At the same time, the method is complicated to operate, requires a lot of equipment, and has low space utilization.

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