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A solvent crystallization separation system for 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene

A technology of dichloronitrobenzene and crystallization separation, applied in solution crystallization, evaporative separation crystallization, heat exchange cooling crystallization and other directions, can solve the problems of high toxicity of CuCN, complex system, cumbersome regeneration operation, etc., and achieves good application prospects and broad Application prospects, the effect of low comprehensive cost

Active Publication Date: 2021-09-07
ZHEJIANG DIBANG CHEM +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

For example: the patent US3144476A mentioned a reactive distillation method, using dimethylformamide (DMF) as a solvent, adding CuCN and 2,3-dichloronitrobenzene to react at the same time, this method has CuCN highly toxic, complex system, high cost, etc. Disadvantages: Patent JP63002956A mentions the use of H-ZSM-5 zeolite molecular sieve adsorption separation to produce 2,3-dichloronitrobenzene with a purity of more than 99%. This method has problems such as small processing capacity, cumbersome regeneration operations, and high cost.
Patent CN102875384A reports a method for extracting and rectifying separation of 3,4-dichloronitrobenzene. Although this method can obtain products deviated from eutectic compositions, it still requires a theoretical grade of more than 60, and the resulting 3,4-dichloronitrobenzene The purity of chloronitrobenzene is only 90%

Method used

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  • A solvent crystallization separation system for 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] The solvent crystallization separation system of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene of the present embodiment is as follows: figure 1 As shown, the two-component mixture of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene (referred to as mixed dichloronitrobenzene feed) is used as the solvent crystallization subsystem I and solvent crystallization subsystem II The external feeds 1 and 2 can be added in the solvent crystallization subsystem I or the solvent crystallization subsystem II according to different compositions. In the material mixing process, the solvent is mixed with the mixed dichloronitrobenzene feed and the recycle material sent by another solvent crystallization subsystem to obtain a solution, and then in the cooling crystallization process, the obtained solution is separated out by a certain cooling procedure Crystals, the obtained crystals are then extracted as products in the solid-liquid separation process, and the remaining so...

Embodiment 2

[0031] The solvent crystallization separation system of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene in this example is similar to that of Example 1. A two-component mixture of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene was used as the external feed 1 of the solvent crystallization subsystem I.

[0032]In the solvent crystallization subsystem I, the content of 3,4-dichloronitrobenzene is 80wt% after the external feed 1, the solvent crystallization subsystem II removes the dichloronitrobenzene of n-hexane and the solvent methanol Enter cooling crystallization, the mass ratio of solvent to external feed 1 is 5:1, the final crystallization temperature is 3°C, and the cooling rate is 0.5°C / min; the crystallization mixture is separated from solid and liquid, and the crystal product is extracted; the effluent material is evaporated by solvent , the mixed dichloronitrobenzene obtained from the solvent removal is sent to the solvent crystallization subsystem II, an...

Embodiment 3

[0035] The solvent crystallization separation system of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene in this example is similar to that of Example 1. A two-component mixture of 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene was used as the external feed 1 of the solvent crystallization subsystem I.

[0036] In the solvent crystallization subsystem I, the content of 3,4-dichloronitrobenzene is 95wt% of the external feed 1, and the dichloronitrobenzene with the solvent carbon tetrachloride removed in the solvent crystallization subsystem II is mixed with the solvent normal After mixing propanol, it enters cooling crystallization, the mass ratio of solvent to external feed 1 is 0.5:1, the final crystallization temperature is -10°C, and the cooling rate is 5°C / min; the crystallization mixture is separated from solid and liquid, and the crystal product is extracted; The effluent material is evaporated by the solvent, and the mixed dichloronitrobenzene obtained from ...

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Abstract

The invention discloses a solvent crystallization and separation system for 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene, including solvent crystals used for crystallization and separation to obtain 3,4-dichloronitrobenzene System I and solvent crystallization subsystem II used for crystallization and separation to obtain 2,3-dichloronitrobenzene; both solvent crystallization subsystem I and solvent crystallization subsystem II include sequential material mixing, cooling crystallization, and solid-liquid separation , solution evaporation and condensation recovery five procedures; solvent evaporation process in solvent crystallization subsystem I solvent removal material is sent to the material mixing process of solvent crystallization subsystem II as the first cycle material, solvent evaporation in solvent crystallization subsystem II The material after the procedure removes the solvent is sent to the material mixing process of the solvent crystallization subsystem I as the second circulating material; the solvent in the solvent crystallization subsystem I is methanol, ethanol, n-propanol, n-butanol or ethyl acetate, and the solvent The solvent in crystallization subsystem II is heptane, carbon tetrachloride, cyclohexane or n-hexane.

Description

technical field [0001] The invention relates to the field of fine chemicals, in particular to a solvent crystallization separation system for 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene. Background technique [0002] 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene are important organic intermediates, widely used in dyes, medicines, pesticides and other fields. Among them, 3,4-dichloronitrobenzene can be used to synthesize o-chloro-p-nitroaniline, 3,4-dichloroaniline, 3-chloro-4-fluoroaniline, 2,4-dichlorofluorobenzene, etc., 2, 3-Dichloronitrobenzene can be used to synthesize 1,2,3-trichlorobenzene, 2,6-dichlorofluorobenzene, 2,6-dichlorobenzonitrile, etc. [0003] The nitration of o-dichlorobenzene mixed acid is the main method to produce 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene. Since this method results in a mixture, there is a need for an efficient method capable of separating 3,4-dichloronitrobenzene and 2,3-dichloronitrobenzene. However,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B01D9/02C07C201/16C07C205/12
CPCB01D9/0004B01D9/0018B01D9/0059C07C201/16C07C205/12
Inventor 吕阳成徐万福兰洲傅伟松黄振夫丁亚刚
Owner ZHEJIANG DIBANG CHEM