Method for continuously preparing dinitrochlorobenzene

Abstract

The invention discloses a method for continuously preparing dinitrochlorobenzene. Multiple dinitration reactors are connected in series for reaction, and mononitrochlorobenzene is continuously added to the first dinitration reactor, and continuously flows through all the dinitration reactors and flows out; a mixed acid nitrating agent is prepared from 75-85% of sulfuric acid, 2-7% of nitric acid and 5-15% of water; the reaction temperature is 40-95 DEG C; and each dinitration reactor is provided with a separation device for separating an organic phase from an inorganic phase, and the inorganic phase is returned into the reactor, thereby keeping the inorganic phase and the organic phase in the required proportion. In the invention, the dinitrochlorobenzene is prepared by continuous reactions, and the reactions are continuously carried out and sequentially completed; chlorobenzene is used for extracting nitrates and nitric acid in an acid phase, thereby lowering the content of the nitric acid in the acid phase and recycling the nitrates in the acid phase; by the invention, the dinitrochlorobenzene can be continuously prepared from two raw materials (chlorobenzene and p-nitrochlorobenzene) by using one set of devices; and the invention has the advantages of low raw material consumption and high production capacity.

Description

[0001] technical field [0002] The invention relates to a method for preparing dinitrochlorobenzene, in particular to a method for continuously preparing dinitrochlorobenzene. Background technique [0003] Dinitrochlorobenzene, referred to as DNCB, is mainly used as an intermediate for the preparation of dyes, pharmaceuticals and pesticides, as a polymerization aid, etc., and its molecular formula is C 6 h 3 Cl (NO 2 ) 2 , it has six isomers in total, and what needs to be produced is dinitrochlorobenzene with a 2,4-DNCB structure. In the products produced with chlorinated benzene as raw materials, 2,4-DNCB generally accounts for about 96%, and 2,6 -DNCB accounts for about 3%, unnitrated mononitrochlorobenzene accounts for 0.2%, and the rest is nitrated by-products. The 2,4-DNCB produced with p-nitrochlorobenzene generally accounts for 99.5%, and the remaining mononitrides and by-products account for 0.5%. [0004] The first stage: nitration of chlorobenzene into mononi...

AI Technical Summary

Problems solved by technology

[0008] The existing production process of dinitrochlorobenzene in China adopts discontinuous production, which generally has low efficiency, high consumption, safety and product quality cannot be guaranteed

[0009] In response to the above-mentioned defects, scientific and technical personnel have conducted a lot of research and published a large number of documents to try to solve them, but these methods all have defects such as low product purity, high raw material consumption, and difficulty in realizing industrialized large-scale continuous production.

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