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3,4-difluorobenzonitrile preparation method

A technology of difluorobenzonitrile and dichlorobenzonitrile, which is applied in the field of preparation of 3,4-difluorobenzonitrile, can solve the problems of high reaction temperature, high energy consumption in the production process, and high price of o-difluorobenzene, and can reduce the The effect of reaction temperature, reducing the generation of three wastes and shortening the reaction time

Active Publication Date: 2018-08-17
江苏丰山生化科技有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This route has short reaction steps, but the price of o-difluorobenzene is relatively high, and cyanide is highly toxic and difficult to industrialize
[0012] Hiroshi Suzuki et al. (The Journal of Fluorine Chemistry, 1991, 52) reported a synthetic method for preparing 3,4-difluorobenzonitrile by fluorine exchange from 3,4-dichlorobenzonitrile, but in the reaction process, There are problems such as high reaction temperature, long time, serious polymerization, dehalogenation and coking of the reaction system, low yield, high energy consumption in the production process, and serious pollution.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] 1. Preparation of catalyst bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-ammonium chloride salt

[0041] Put 114g (1mol) of 1,3-dimethyl-2-imidazolidinone and 300g of toluene into the dry reaction flask, slowly add 100g (0.34mol) of triphosgene (0.34mol) and 200g of toluene to the reaction flask under the condition of 0-5°C Solution, react at room temperature for 2 hours after the dropwise addition, then slowly add ammonia (20g, 1.18mol)-toluene 100g solution dropwise to the reaction system at 0-5°C, after the dropwise addition, raise the temperature to 80°C to react 6 After the reaction, the toluene was removed to obtain the intermediate 1,3-dimethyl-2-imidazolinimine, which was set aside.

[0042]Put 114g (1mol) of 1,3-dimethyl-2-imidazolidinone and 300g of toluene into another dry reaction flask, and slowly add 100g (0.34mol) of toluene 200g to the reaction flask under the condition of 0-5°C Solution, react at room temperature for 2 hours after the dropwise addition, then ...

Embodiment 2

[0047] Embodiment 2 utilizes recovered catalyst and solvent to apply (eighth time) to prepare 3,4-difluorobenzonitrile

[0048] Drop into the DMI-catalyst solution (and add DMI to 300g) and anhydrous Potassium Fluoride (170g, 2.93mol) that embodiment 1 reclaims in the reaction flask of drying band rectification column, then add toluene 150g reflux and divide water about 1 Hours, after the water separation is completed, the toluene is evaporated and recovered for the next application, and then 3,4-dichlorobenzonitrile (200g, 1.16mol), bis-(N,N'-1,3-dimethyl- 2-imidazolinyl)-ammonium chloride salt (8g, 0.032mol), PEG2000 (3g) and sodium metabisulfite (3g), the temperature was raised to 200-215°C for 4-5 hours, and the rectification column received 3,4-di The crude product of fluorobenzonitrile was 150 g, and the crude product was subjected to secondary rectification to obtain 140 g of 3,4-difluorobenzonitrile product with a purity of 99% and a molar yield of 87%.

[0049] Cool ...

Embodiment 3

[0051] Put 250 g of 1,3-dimethyl-2-imidazolinone (DMI) and anhydrous potassium fluoride (170 g, 2.93 mol) into a dry reaction flask with a rectification column, then add 100 g of toluene to reflux and divide the water for about 2 Hours, after the water separation is finished, the toluene is evaporated and recovered for the next application, and then 3,4-dichlorobenzonitrile (200g, 1.16mol), the bis-(N,N'-1,3- Dimethyl-2-imidazolinyl)-ammonium chloride salt (40g, 0.16mol), polyacrylamide (10g) and sodium thiosulfite (20g), the temperature was raised to 190-200°C for 5 hours, and the rectification column received The crude product of 3,4-difluorobenzonitrile was 160g, and the crude product was subjected to secondary rectification to obtain 145g of 3,4-difluorobenzonitrile product with a purity of 99% and a molar yield of 90%.

[0052] Cool and filter after the reaction, rinse the filter cake with DMI, collect the filtrate containing the catalyst and directly apply it to the next...

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Abstract

The invention discloses a 3,4-difluorobenzonitrile preparation method. The 3,4-difluorobenzonitrile preparation method comprises the following steps of taking 3,4-difluorobenzonitrile as a raw material, potassium fluoride as a fluorinated reagent and bis-(N,N'-1,3-dimethyl-2-imidazolinyl)-chloride ammonium salt as a phase transfer catalyst, then adding a reducing agent and a dispersant, and performing reaction to prepare the 3,4-difluorobenzonitrile. In the method, the temperature of fluorination reaction is relatively low, the reaction time is short, the total molar yield can reach about 90 percent, and the solvents and the catalyst can be recycled; produced potassium chloride in reaction becomes a pure product with the purity being 99 percent or above after recrystallization, and the pure product can be directly sold, so that the production cost is reduced; in addition, the technology is safe and environmentally friendly, is small in quantities of three wastes (waste water, waste solid and waste gas) and is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of preparation of chemical intermediates, and in particular relates to a preparation method of 3,4-difluorobenzonitrile. Background technique [0002] 3,4-Difluorobenzonitrile is the key intermediate for the preparation of cyhalofop-methyl, followed by the preparation of 3,4-difluoroaniline, 3,4-difluorobenzoic acid, 3,4-difluorobenzene trifluoride, etc. The intermediate of chemical products can be used in the synthesis of pesticides, medicines and fluorine-containing liquid crystal materials. The most important thing at present is to find the cheapest and easy-to-obtain scheme to prepare 3,4-difluorobenzonitrile. [0003] The key intermediate for the preparation of cyhalofop-ethyl is 3,4-difluorobenzonitrile. Cyhalofop-ethyl has excellent herbicidal properties and is a post-emergent rice field that exhibits high activity and selectivity against weeds at very low doses. Herbicides are mainly used to control importan...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C253/30C07C255/50
CPCC07C253/30C07C255/50Y02P20/584
Inventor 陈宝明王晋阳张庆宝马添天豆飞扬姚金莉李星李俊卿王波单永祥殷平殷凤山
Owner 江苏丰山生化科技有限公司
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