Process for synthesizing 3,4-difluorobenzonitrile

Abstract

The invention discloses a process for synthesizing 3,4-difluorobenzonitrile. According to the process, 3,4-difluorobenzonitrile with the purity of over 99% is obtained through taking 3,4-dichlorobenzonitrile as a raw material, taking potassium fluoride as a fluorination reagent, taking 1,3-dimethyl-2-imidazolidinone as a reaction solvent, taking bis-(N-bis(dimethylamino)methylene)-iminium chloride as a catalyst, enabling reactants to react for 2-3 hours at the temperature of 130-150 DEG C and react for 5-6 hours at the temperature of 180-200 DEG C, then ending reaction, filtering a reaction solution and then rectifying under reduced pressure, and the yield can reach 85%. Rectification mother liquor (containing the catalyst) is mechanically applied to next-batch reaction directly. According to the process disclosed by the invention, the raw material is easy to obtain, the reaction conditions are mild, the reaction time is short, the operation is simple, the yield is high, the reaction solvent (containing the catalyst) can be repeatedly applied mechanically, the cost is low, and the emission of waste gases, waste water and waste residues is little, so that the process is applicable to industrial production.

Description

technical field

[0001] The invention relates to the technical field of synthesis of 3,4-difluorobenzonitrile, a key intermediate of the rice herbicide cyhalofop-ethyl, in particular to a synthesis process of 3,4-difluorobenzonitrile. Background technique

[0002] 3,4-Difluorobenzonitrile can be used as an intermediate for the synthesis of various medicines, dyes, and liquid crystal materials, and is also an important intermediate for the selective herbicide cyhalofop-ethyl. Cyhalofop-ethyl is a selective herbicide for rice, which is quite safe for transplanted and direct-seeded rice, and is internationally recognized as an excellent rice herbicide. With the rapid development of cyhalofop-ethyl, the market demand for 3,4-difluorobenzonitrile is huge.

[0003] There are many synthetic routes of 3,4-difluorobenzonitrile reported in the literature, and the most economical route is the direct fluorination synthesis of 3,4-dichlorobenzonitrile. Generally, potassium fluoride is u...

Examples

Embodiment 1

[0029] Add 150g of 3,4-dichlorobenzonitrile, 450g of 1,3-dimethyl-2-imidazolidinone, 100g of cyclohexane into a 1000ml reactor with stirrer, reflux separator and thermometer, and heat up to 90°C. Reflux water diversion 1 hour, after treating that there is no water in the water separator, drop into 75g spray-dried potassium fluoride, two-(N-bis(dimethylamino)methylene)-imine chloride 10g, be warming up to 140°C, reflux and water separation for 3 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, continue to heat up to 180°C, and the reaction is over for 5h.

[0030] Dilute the obtained reaction solution with toluene and filter under reduced pressure to remove salt, wash the filter cake 3 times with toluene, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect The 105°C fraction was 79g, the GC purity was 99%, and the yield was 65%.

Embodiment 2

[0032] Add 150g of 3,4-dichlorobenzonitrile, 450g of 1,3-dimethyl-2-imidazolidinone, 100g of toluene into a 1000ml reaction kettle equipped with a stirrer, reflux separator, and thermometer, heat up to 120°C, and reflux Water for 2 hours, after no water comes out in the water separator, put in 150g of spray-dried potassium fluoride, 15g of bis-(N-bis(dimethylamino)methylene)-imide chloride, and heat up to 130°C , reflux and water separation reaction for 2 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, continue to heat up to 200 ° C, and the reaction is completed for 6 hours.

[0033] Dilute the obtained reaction liquid with toluene, then filter under reduced pressure, remove salt, wash the filter cake with toluene 3 times, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect at the top of the tower 84g fraction at 90-105°C, GC purity 99%, yield 70%.

Embodiment 3

[0035] Add 150g of 3,4-dichlorobenzonitrile, 300g of 1,3-dimethyl-2-imidazolidinone, 100g of toluene into a 1000ml reactor with stirrer, reflux separator, and thermometer, heat up to 120°C, reflux Water for 1.5 hours, after no water has come out in the water separator, put in 150g of spray-dried potassium fluoride, 15g of bis-(N-bis(dimethylamino)methylene)-imide chloride, and heat up to 150°C , refluxed and separated water for 2.5 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, and continued to heat up to 180°C, and the reaction was completed for 5 hours.

[0036] Dilute the obtained reaction liquid with toluene, then filter under reduced pressure, remove salt, wash the filter cake with toluene 3 times, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect at the top of the tower The fraction at 90-105°C was 87.3g, the GC purity was 99%, and the yield was 72%.

technical field

[0001] The invention relates to the technical field of synthesis of 3,4-difluorobenzonitrile, a key intermediate of the rice herbicide cyhalofop-ethyl, in particular to a synthesis process of 3,4-difluorobenzonitrile. Background technique

[0002] 3,4-Difluorobenzonitrile can be used as an intermediate for the synthesis of various medicines, dyes, and liquid crystal materials, and is also an important intermediate for the selective herbicide cyhalofop-ethyl. Cyhalofop-ethyl is a selective herbicide for rice, which is quite safe for transplanted and direct-seeded rice, and is internationally recognized as an excellent rice herbicide. With the rapid development of cyhalofop-ethyl, the market demand for 3,4-difluorobenzonitrile is huge.

[0003] There are many synthetic routes of 3,4-difluorobenzonitrile reported in the literature, and the most economical route is the direct fluorination synthesis of 3,4-dichlorobenzonitrile. Generally, potassium fluoride is u...

Examples

Embodiment 1

[0029] Add 150g of 3,4-dichlorobenzonitrile, 450g of 1,3-dimethyl-2-imidazolidinone, 100g of cyclohexane into a 1000ml reactor with stirrer, reflux separator and thermometer, and heat up to 90°C. Reflux water diversion 1 hour, after treating that there is no water in the water separator, drop into 75g spray-dried potassium fluoride, two-(N-bis(dimethylamino)methylene)-imine chloride 10g, be warming up to 140°C, reflux and water separation for 3 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, continue to heat up to 180°C, and the reaction is over for 5h.

[0030] Dilute the obtained reaction solution with toluene and filter under reduced pressure to remove salt, wash the filter cake 3 times with toluene, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect The 105°C fraction was 79g, the GC purity was 99%, and the yield was 65%.

Embodiment 2

[0032] Add 150g of 3,4-dichlorobenzonitrile, 450g of 1,3-dimethyl-2-imidazolidinone, 100g of toluene into a 1000ml reaction kettle equipped with a stirrer, reflux separator, and thermometer, heat up to 120°C, and reflux Water for 2 hours, after no water comes out in the water separator, put in 150g of spray-dried potassium fluoride, 15g of bis-(N-bis(dimethylamino)methylene)-imide chloride, and heat up to 130°C , reflux and water separation reaction for 2 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, continue to heat up to 200 ° C, and the reaction is completed for 6 hours.

[0033] Dilute the obtained reaction liquid with toluene, then filter under reduced pressure, remove salt, wash the filter cake with toluene 3 times, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect at the top of the tower 84g fraction at 90-105°C, GC purity 99%, yield 70%.

Embodiment 3

[0035] Add 150g of 3,4-dichlorobenzonitrile, 300g of 1,3-dimethyl-2-imidazolidinone, 100g of toluene into a 1000ml reactor with stirrer, reflux separator, and thermometer, heat up to 120°C, reflux Water for 1.5 hours, after no water has come out in the water separator, put in 150g of spray-dried potassium fluoride, 15g of bis-(N-bis(dimethylamino)methylene)-imide chloride, and heat up to 150°C , refluxed and separated water for 2.5 hours to obtain the intermediate 3-chloro-4fluorobenzonitrile, and continued to heat up to 180°C, and the reaction was completed for 5 hours.

[0036] Dilute the obtained reaction liquid with toluene, then filter under reduced pressure, remove salt, wash the filter cake with toluene 3 times, transfer the filtrate to a rectification kettle for rectification under reduced pressure, control the vacuum degree to 0.08-0.09MPa, and collect at the top of the tower The fraction at 90-105°C was 87.3g, the GC purity was 99%, and the yield was 72%.

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