Method for preparing 2,3-dichlorin fluorobenzene

A technology of dichlorofluorobenzene and dichloro, which is applied in the field of fluorobenzene compounds, can solve the problems of difficult process conditions, complex process, high production cost, etc., achieve simple and easy reaction process, make full use of resources, and reduce production cost Effect

Inactive Publication Date: 2009-01-07
常山新星高科化工技术有限公司
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Problems solved by technology

The preparation of 2,6-dichlorofluorobenzene by the above method has problems such as c

Method used

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Embodiment 1

[0025] Embodiment 1 of the present invention: a preparation method of 2,6-dichlorofluorobenzene, the method first uses 3,5-dichloro-4-fluoronitrobenzene as a raw material, and is produced by iron powder reduction or catalytic hydrogenation Obtain 3,5-dichloro-4-fluoroaniline, when adopting catalytic hydrogenation, get final product according to conventional process, when utilizing iron powder reduction as follows:

[0026] a. Add 100kg of water, 5kg of acetic acid (HAc) and 100kg of iron powder into a 500L reactor, and add 100kg of 3,5-dichloro-4-fluoronitrobenzene in 2 batches or 3 batches under reflux to obtain product A;

[0027] b. Reflux reaction of product A for 2.5-3 hours, and use gas chromatography (GC) to track to no raw material peaks to obtain product B;

[0028] c. Cool product B to 40°C to crystallize, rinse with water on the sieve to remove fine iron powder, and obtain product C;

[0029] d. Dissolve product C with ethanol, filter off the iron powder again to o...

Embodiment 2

[0032] Embodiment 2 of the present invention: 3, the preparation of 5-dichloro-4-fluoroaniline is the same as in Example 1, and then in the presence of a reducing agent, 3,5-dichloro-4-fluoroaniline is replaced by diazonium hydrogen 2,6-Dichlorofluorobenzene is obtained:

[0033] Add reducing agent ethanol (1050g), 3,5-dichloro-4-fluoroaniline (180g) and concentrated sulfuric acid (80g) into a 2L reaction kettle, heat up to 80°C and reflux, add solid sodium nitrosode (85g) , heat preservation reaction for 3 hours, evaporated about 650g of ethanol, added appropriate amount of water, separated the oil layer, neutralized to neutral, and steam distilled to obtain 100g of 2,6-dichlorofluorobenzene (89%, GC), yield 53.94%.

[0034] In each embodiment, during the diazonium hydrogen replacement reaction, the reducing agent used can also be hypophosphite, and other lower alcohols, such as ethanol or isopropanol, in addition to hypophosphorous acid and ethanol.

[0035] In each embodim...

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Abstract

The invention discloses the preparation method of 2,6-dichlorofluorobenzene, which comprises the following steps: preparing 3,5-dichloro-4-fluoroaniline from 3,5-dichloro-4-fluorobenzonitrile by iron reduction or catalytic hydrogenation; and replacing diazo group in 3,5-dichloro-4-fluoroaniline by hydrogen in the presence of a reducing agent to obtain 2,6-dichlorofluorobenzene. The method can prepare 2,6-dichlorofluorobenzene by a reasonable process, and has the advantages of simple and easy reaction process and high yield of the product. Additionally, 3,5-dichloro-4-fluoroaniline can be selected from (1) 3,4-dichloronitrobenzene rectification residues from combined production or byproduct of 3,4-dichloronitrobenzene; (2) rectification tailings of 2,3,4-trifluoronitrobenzene; and (3) rectification residues of 3-chloro-4-fluoronitrobenzene. Accordingly, the materials can be easily obtained to fully utilize the resources and reduce the production cost.

Description

technical field [0001] The invention relates to a preparation method of 2,6-dichlorofluorobenzene, which belongs to the technical field of fluorobenzene compounds. Background technique [0002] 2,6-Dichlorofluorobenzene, whose molecular formula is C 6 h 3 Cl 2 F, used as an intermediate for medicine, pesticide and dyestuff. At present, the preparation of 2,6-dichlorofluorobenzene adopts the following method: 1,3-chloro-fluoroaniline and 2,6-dichlorofluorobenzene co-production method. For example, the application number is CN03150688.7, the publication number is CN1515542, the publication date is 2004.07.28, and the Chinese patent titled "A method for co-producing 3-chloro-fluoroaniline and 2,6-dichlorofluorobenzene" stated. 2. Using 2-fluoro-3-chloronitrobenzene as raw material, 2,6-dichlorofluorobenzene can be obtained through reduction and diazotization of chlorine. 3. Using 2,6-dichloroaniline as raw material, undergo diazotization and chlorination reaction to obtai...

Claims

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Application Information

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IPC IPC(8): C07C25/13C07C17/35
Inventor 陈生荣陈志明徐德忠沈志良林仕国张宏
Owner 常山新星高科化工技术有限公司
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