A kind of preparation method of 3,4-difluorobenzonitrile

Abstract

A preparation method for 3,4-difluorobenzonitrile, using 3,4-dichlorobenzonitrile as raw material, potassium fluoride as fluorinating reagent, bis-(N,N'-1,3-dimethyl- 2-imidazolinyl)-ammonium chloride salt is a phase-transfer catalyst, and then a reducing agent and a dispersant are added to react to prepare 3,4-difluorobenzonitrile. In this method, the fluorination reaction temperature is low, the reaction time is short, the total molar yield can reach about 90%, the solvent and the catalyst can be recycled, and the potassium chloride generated in the reaction is recrystallized to become a fluoride with a purity of more than 99%. The pure product can be sold directly, which reduces the production cost, and the process is safe and environmentally friendly, and the amount of three wastes is small, which 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...

Examples

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...

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...

Examples

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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