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Preparation method of 2, 6-dichlor fluorbenzene

A technology for dichlorofluorobenzene and dichloride, which is applied to the synthesis field of organic compounds, can solve the problems of difficult control of process conditions, complicated process, low product yield, etc., and achieves easy control of process conditions, wide sources, and reduced production costs. Effect

Inactive Publication Date: 2010-02-10
ZHEJIANG UNIV
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Problems solved by technology

Adopt above-mentioned method to prepare 2,6-dichlorofluorobenzene, there are technological process complexity, technological condition is difficult to control, product yield is low or the problems such as high production cost all remain to be solved
[0005] 2,3,4-Trifluoronitrobenzene is an important intermediate for the synthesis of ofloxacin. One route to synthesize this compound is to obtain the target product through nitration and fluorination of 2,6-dichlorofluorobenzene. One step will produce by-product 3,5-dichloro-4-fluoronitrobenzene. At present, the by-product 3,5-dichloro-4-fluoronitrobenzene often becomes waste because it has not been effectively utilized, and sometimes even produces pollution, it is of great significance to develop its valuable utilization

Method used

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  • Preparation method of 2, 6-dichlor fluorbenzene
  • Preparation method of 2, 6-dichlor fluorbenzene
  • Preparation method of 2, 6-dichlor fluorbenzene

Examples

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Effect test

Embodiment 1、3

[0027] Embodiment 1, the preparation method of 3,5-dichloro-4-fluoroaniline, with 3,5-dichloro-4-fluoronitrobenzene as raw material, the following steps are carried out successively:

[0028] (1) Dissolve 105g of 3,5-dichloro-4-fluoronitrobenzene in 200mL of ethanol, stir evenly, there is a strong endothermic phenomenon. Pour 70g of iron powder and 150g of ammonium chloride into a 1L three-necked flask, add 250mL of water to mix, start heating, and start adding the ethanol solution of the reactant dropwise when it reaches 60°C, and the dropwise addition is completed in about 90 minutes. At this time, the temperature is 78°C. When the reaction solution starts to reflux, the temperature is 94°C, and heat and keep warm.

[0029] (2) After reacting for 2 hours, the reaction liquid was cooled to room temperature, and 200 mL of toluene was added for extraction. Suction filtration to remove iron sludge, wash the filtrate with water, and filter to remove the precipitated Fe(OH)x prec...

Embodiment 2

[0030] Embodiment 2, a kind of preparation method of 2,6-dichlorofluorobenzene, take 3,5-dichloro-4-fluoroaniline as starting material, carry out the following steps successively:

[0031] (1) Concentrated H with a mass fraction of 98% 2 SO 4 6g (0.06mol) was diluted with water to 30g, added to a 250mL three-necked flask, and 3.6g (0.02mol) of 3,5-dichloro-4-fluoroaniline was added in batches in an ice bath, and reacted at room temperature for 0.7h. The reaction solution ( That is, the temperature of the solution containing ammonium salt) drops to 0°C; then drop 20mL of an aqueous solution containing 1.50g (0.021mol) of sodium nitrite, and react at 0-5°C for 1 hour, then use starch potassium iodide test paper to detect the end point, and the test paper turns blue , stop responding.

[0032] (2) Slowly add 3.5g (0.04mol) of ethyl acetate dropwise into the solution containing diazonium salt prepared in the above step (1), heat up to 70°C and reflux, and the nitrogen gas genera...

Embodiment 3

[0034] Embodiment 3, a kind of preparation method of 2,6-dichlorofluorobenzene, take 3,5-dichloro-4-fluoroaniline as starting material, carry out the following steps successively:

[0035] (1) Concentrated H with a mass fraction of 98% 2 SO 4 4g (0.04mol) was diluted with water to 20g, added to a 250mL three-necked flask, and 3.6g (0.02mol) of 3,5-dichloro-4-fluoroaniline was added in batches in an ice bath, and reacted at room temperature for 0.5h. Lower to -5°C; then drop into 20mL of aqueous solution containing 1.66g (0.024mol) of sodium nitrite, react at -5~0°C for 1 hour, use starch potassium iodide test paper to detect the end point, the test paper turns blue, and the reaction is stopped.

[0036] (2) Slowly add 3.5g (0.04mol) of ethyl acetate dropwise into the solution containing diazonium salt prepared in the above step (1), heat up to 70°C and reflux, and the nitrogen gas generated by the decomposition of diazonium salt will continue to form bubbles The form escapes...

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Abstract

The invention discloses a preparation method of 2, 6-dichlor fluorbenzene, including that diazonium salt is made by taking 3, 5-dichlor-4-fluoroanilines as raw material and the 2, 6-dichlor fluorbenzene is obtained through diazo hydrogen replacement in the presence of reducing agent. The method concretely includes the following steps: (1) 3, 5-dichlor-4-fluorbenzene is taken as raw material and reacts with inorganic acid, so as to obtain solution containing ammonium salt; (2) the solution containing ammonium salt reacts with nitrite aqueous solution, so as to obtain solution containing diazonium salt; (3) reducing agent is dropwise added into the solution containing diazonium salt until reaction product causes starch potassium iodide paper to turn blue; (4) the reaction solution obtained by the step (3) is subject to dispensing, washing and steam distillation, so as to obtain the product 2, 6-dichlor fluorbenzene. The preparation method has the characteristics of simple technology, high yield and low cost.

Description

technical field [0001] The invention relates to a method for synthesizing organic compounds, in particular to a method for synthesizing 2,6-dichlorofluorobenzene (2,6-dichlorofluorobenzene). Background technique [0002] 2,6-Dichlorofluorobenzene, whose molecular formula is C 6 h 3 Cl 2 F, its structural formula is shown in S-1, the pure product is white crystal, the melting point is 37-40°C, the boiling point is 168-169°C, it is an important fine chemical intermediate, mainly used in the synthesis of fluoroquinolones and pesticides. [0003] [0004] According to comprehensive literature reports, the preparation of 2,6-dichlorofluorobenzene adopts the following methods at present: 1. With 2,6-dichloroaniline as raw material, through diazotization fluorination reaction, 2,6-dichlorofluorobenzene is obtained, The yield is about 80%; 2. Using 2-fluoro-3-chloronitrobenzene as raw material, 2,6-dichlorofluorobenzene is obtained through reduction and diazotization of chloro...

Claims

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Application Information

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IPC IPC(8): C07C25/13C07C17/35
Inventor 陈新志计立钱超
Owner ZHEJIANG UNIV
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