Production method for improving purity of o-nitrochlorobenzene

Abstract

The invention discloses a production method for improving the purity of o-nitrochlorobenzene. The production method comprises the following steps that anhydrous chlorobenzene, a sulfuric acid solutionand a nitric acid solution are added into a nitrating kettle for a reaction until the amounts of substances do not change anymore; an obtained nitrochlorobenzene mixture is neutralized, filtered andwashed to obtain a precipitant; the washed nitrochlorobenzene mixture and water are heated and then enter an evaporation chamber to achieve azeotropy of the mixture and water, an azeotrope enters a separation chamber, then cooling is conducted to 10-30 DEG C, and filtering is conduced to obtain a crude product of o-nitrochlorobenzene; the crude product is transferred into a washing kettle to be washed and then dried, and then the high-purity o-nitrochlorobenzene is obtained. According to the production method, the nitrochlorobenzene mixture and water are subjected to flashing evaporation in the evaporation chamber, and separation is conducted to obtain the high-purity o-nitrochlorobenzene. According to the production method, an azeotropy separation process is adopted for avoiding the crystallization and heating process, the energy consumption can be effectively lowered, the purity of the product is improved at the same time, complete separation of three kinds of nitrochlorobenzene is achieved, the content of the product o-nitrochlorobenzene reaches 99% or above, and the yield reaches 98% or above.

Description

technical field [0001] The invention relates to the technical field of pesticide synthesis, in particular to a production method for improving the purity of o-nitrochlorobenzene. Background technique [0002] Nitrochlorobenzene is an intermediate of many fine chemical products such as medicine, pesticide and dye. The production of nitrochlorobenzene is based on chlorobenzene, and the mixed acid of nitric acid and sulfuric acid is used as the nitrating agent for nitration. The crude product obtained by nitration needs to be washed with alkali and water, and then separated and purified by a rectification tower to obtain p-nitrochlorobenzene. Chlorobenzene and o-nitrochlorobenzene. [0003] o-nitrochlorobenzene, p-nitrochlorobenzene and its derivative product p-nitroanisole are important intermediates for dyes, medicines, pesticides, and spices. The main production route is: nitration reaction of chlorobenzene at a certain temperature and pressure , to generate a nitrochlorob...

AI Technical Summary

Problems solved by technology

[0005] Under the current technical conditions, it is feasible to continue to separate and purify the components in this part of the mixture by rectification-crystallization, but due to the similar physical properties, it is very difficult to implement

In order to obtain m-nitrochlorobenzene finished products, the m-nitrochlorobenzene in the material taken from the top of the rectification tower must be greater than 80% before crystallization, otherwise the purity of the m-nitrochlorobenzene product is insufficient or the yield is extremely low due to mutual solubility, and the intermediate The boiling points of nitrochlorobenzene and p-nitrochlorobenzene are 237°C and 239°C respectively, and the difference between the boiling points is only 2°C. During rectification, a high reflux ratio and a small amount taken from the top of the tower are required to meet the process requirements. High energy consumption and long production cycle

Images