Method for preparing high-purity 2, 4-dinitrochlorobenzene through nitration of o-nitrochlorobenzene

Abstract

The invention relates to a method for preparing high-purity 2, 4-dinitrochlorobenzene through nitration of o-nitrochlorobenzene. The method comprises the following steps: S1, performing nitration reaction: by taking an N2O5 / HNO3 solution with a certain concentration as a nitrating agent, carrying out nitration on o-nitrochlorobenzene serving as a raw material to obtain a mixed mother liquor, wherein the mixed mother liquor comprises 2, 4-dinitrochlorobenzene and 2, 6-dinitrochlorobenzene; and S2, separating and purifying: S21: conveying the mixed mother liquor of 2.4-dinitrochlorobenzene and 2.6-dinitrochlorobenzene into a crystallizer, and cooling to 15 + / -1 DEG C; S22, gradually raising the temperature of the mixed mother liquor cooled in step S21 to sweat the crystals; S23, in the heating sweating process, firstly collecting mixed low oil, wherein the mixed low oil contains 2, 6-dinitrochlorobenzene with the volume fraction of 30 + / -1%; S24, collecting mixed high oil, wherein the mixed high oil contains 2, 6-dinitrochlorobenzene with the volume fraction of 10 + / -1%; and step S25, finally obtaining 2, 4-dinitrochlorobenzene crystals with the purity of more than 99.5%. The o-nitrochlorobenzene is adopted for nitration, and the used nitrating agent can be recycled. The purification method has the advantages of low energy consumption, low temperature and no three wastes, and is the cleanest separation method at present.

Description

technical field [0001] The invention relates to a method for preparing high-purity 2,4-dinitrochlorobenzene by nitration of o-nitrochlorobenzene, which belongs to the technical field of purification methods of chemical products. Background technique [0002] 2.4-Dinitrochlorobenzene is a light yellow or yellow-brown needle-like crystal with a bitter almond smell, and its molecular formula is C 6 h 3 ClN 2 o 4 , its molecular weight is 202.56, and its relative density is 1.69g / cm 3 , boiling point 315°C, melting point 53.4°C, flash point 194°C, insoluble in water, soluble in ether, benzene, ethanol and other organic solvents, mainly used as raw materials for dyes, pesticides, medicines, etc., and can be used to produce sulfur black and dinitrate phenol, dinitroaniline and m-phenylenediamine. [0003] The production of 2.4-dinitrochlorobenzene has chlorobenzene method and o-nitrochlorobenzene method. The cost of the chlorobenzene method is relatively high, the purity of ...

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Problems solved by technology

The cost of the chlorobenzene method is relatively high, the purity of the product produced by the o-nitrochlorobenzene method cannot meet the requirements, and the isomers of the nitro mixture are generated, and their chemical properties are very close, especially the boiling point is closer. In the prior art It is not only difficult to separate by rectification separation, but also nitro compounds are easy to decompose at high temperature and may explode, posing a great safety hazard

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