Method for separating nitrochlorobenzene meta-position oil

Abstract

The invention discloses a method for separating nitrochlorobenzene meta-position oil, which comprises the following steps of: adding nitrochlorobenzene meta-position oil and aqueous ammonia into an autoclave, heating in the autoclave, and keeping the reaction temperature and the reaction pressure after the reaction starts; slowly reducing the pressure and reducing the temperature after the reaction is completed, and reclaiming ammonia during reducing the pressure and the temperature; pressing the reacted materials to a demixing tank, standing and demixing, and delivering the lower oil material phase to an intermediate tank; pumping the oil phase material in the intermediate tank into a vacuum light component removal tower, removing un-reacted meta-nitrochlorobenzene from the top of the tower, reclaiming the meta-nitrochlorobenzene, recovering a mixed material containing p-nitroaniline and o-nitroaniline from the autoclave, and feeding the mixed material into a mixing tank; and pumping the material in the mixing tank into a vacuum falling film rectifying tower, recovering the o-nitroaniline from the top of the tower, collecting the cooled o-nitroaniline, recovering the p-nitroaniline from the autoclave, and collecting the cooled p-nitroaniline. By the method, the problem of difficult treatment of much wastewater caused by washing with a large amount of water in the conventional production process is solved, and the qualities of the obtain p-nitroaniline and the obtained o-nitroaniline are improved.

Description

technical field [0001] The invention relates to ammoniation and rectification separation technology in organic chemical production, in particular to a method for separating meta-oil of nitrochlorobenzene. Background technique [0002] The separation method of existing nitrochlorinated benzene meta-position oil mainly contains two kinds: [0003] 1. Directly carry out rectification and separation of meta-nitrobenzene oil, which is a mixture of three substances: m-nitrochlorobenzene, o-nitrochlorobenzene and p-nitrochlorobenzene. The boiling points are relatively close: 235.5°C for m-nitrochlorobenzene, 245.5°C for o-nitrochlorobenzene, and 242°C for p-nitrochlorobenzene. It is more difficult to separate by rectification. The isolated 1t of m-nitrochlorobenzene ( content exceeds 95%), steam consumption is 70-80t, and the content of the separated o- and p-nitrochlorinated benzene products is low. [0004] 2. Use sodium alkoxide to etherify meta-oil, m-nitrochlorobenzene does ...

AI Technical Summary

Problems solved by technology

The disadvantages of the method for producing p- and o-nitroaniline in the above-mentioned existing devices are: two kinds of substances need to be used for production in different autoclaves respectively, that is, two production lines are produced separately, and the p- and o-nitroanilines of better quality must be used. Chlorinated benzene raw material, otherwise, either the by-product o-nitroaniline in p-nitroaniline is more or the by-product p-nitroaniline in o-nitroaniline is more, and the simple washing and distillation in the back are not enough to remove impurities, resulting in The quality of the finished product cannot be the best, and it is difficult to achieve more than 99.7%, or even 99.9%, which not only results in a large amount of washing water and high wastewater treatment costs, but also uses higher-quality raw materials - p-, o-nitrochlorobenzene, and the cost of raw materials is high , thus making the overall production cost higher

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