Method of preparing nitrochlorobenzene by adopting vacuum concentration process

Abstract

The invention discloses a method of preparing nitrochlorobenzene by adopting a vacuum concentration process. The production method specifically comprises the following steps: carrying out a reaction on Chlorobenzene and nitric acid under the action of sulfuric acid to generate a nitrochlorobenzene mixture; settling and separating the nitrochlorobenzene mixture; concentrating waste sulfuric acid generated by nitrification in vacuum to be applied mechanically; neutralizing, washing and distilling the acidic nitrochlorobenzene mixture; drying the neutral nitrochlorobenzene mixture to remove chlorobenzene and water and the like, and obtaining a coarse product nitrochlorobenzene mixture; and then separating p-nitrophenol and o-nitrophenol products and meta-position oil rich in m-nitrochlorobenzene and high boiling point organic matter waste liquor by means of a multi-time crystallizing separating method. The nitrified waste acid is concentrated and dehydrated in vacuum, so that the concentration of sulfuric acid exceeds 80%, the sulfuric acid and nitric acid are prepared to a mixed acid to be recycled, the economical benefit is improved and the purity of the product is improved. In theproduction process of the nitrochlorobenzene, the waste acid and the high boiling point organic matter waste liquor are recycled, the green, environmentally-friendly and pollution-free theory is met,and the economical benefit and practicality are reflected.

Description

technical field [0001] The invention relates to the technical field of pesticide synthesis, in particular to a method for preparing nitrochlorobenzene by adopting a vacuum concentration process. 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 generat...

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

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