The preparation method of 3,4-difluorobenzonitrile

Abstract

The invention discloses a 3, 4-difluorobenzonitrile preparation method comprising the following steps: (1) reacting 1, 2-difluorobenzene with trichloroacetic chloride in the presence of a lewis acid catalyst at 0-40 DEG C for synthesis of 3, 4-difluoro-(alpha, alpha, alpha-trichloroacetic) benzene; (2) reacting the 3, 4-difluoro-(alpha, alpha, alpha-trichloroacetic) benzene with ammonia at -10-60 DEG C to obtain 3, 4-difluorobenzamide; (3) reacting the 3, 4-difluorobenzamide with a halogen-containing dehydration reagent and a catalyst at 30-80 DEG C to obtain 3, 4-difluorobenzonitrile. The 3, 4-difluorobenzonitrile preparation method overcomes the defects that in the prior art the raw material price is high, intermediates are highly toxic, reaction conditions are harsh, the reaction yield is poor, the purity is low, and the like, and is a 3, 4-difluorobenzonitrile synthesis process having the advantages of being easy to industrialization, simple in operation, high in yield and high in product purity.

Description

technical field

[0001] The invention belongs to the field of organic chemistry, and relates to a chemical raw material 3,4-difluorobenzonitrile, in particular to a new method for preparing 3,4-difluorobenzonitrile. Background technique

[0002] 3,4-Difluorobenzonitrile is a key intermediate in the synthesis of the phenoxypropionate herbicide cyhalofop-methyl. A variety of methods have been reported for the synthesis of 3,4-difluorobenzonitrile.

[0003] The methods using traditional synthesis techniques mainly include the following:

[0004] (l) Using 1,2-difluorobenzene as a raw material, it is synthesized through steps such as nitration, reduction, diazotization, and nitrilation. Since both 3,4-dichloronitrobenzene and 3,4-difluoroaniline Belong to carcinogen, cuprous cyanide raw material also belongs to highly poisonous, this law route is longer, and environmental pollution is serious.

[0005] (2) With 3,4-difluorobenzoic acid as raw material, it is prepared through a...

Examples

Embodiment 1

[0030] Add 228.4kg (2.0kmol) of 1,2-difluorobenzene, 382.4kg (2.2kmol) of trichloroacetyl chloride and 1600kg of dichloroethane into the dry reactor, stir to dissolve, add anhydrous zinc chloride 220 kg, a large amount of gas escaped, and the reaction temperature was controlled at 25-30°C under an ice-water bath. After the raw materials were completely reacted, the reaction liquid was poured into ice water under stirring, and 2093 kg containing 3,4-difluoro -(α,α,α-Trichloroacetyl)benzene 493.0 kg (1.9 kilomole) dichloroethane solution, yield 95%.

[0031] In another reactor, add 2093 kg of 3,4-difluoro-(α, α, α-trichloroacetyl) benzene 493.0 kg (1.9 kilomole) of dichloroethane solution, stir ammonia gas and control The reaction temperature is 20-30°C, and a white solid precipitates out. After the raw materials are completely reacted, filter, wash, and dry to obtain 289.6 kg (1.843 kmol) of 3,4-difluorobenzamide, with a yield of 97%

[0032] Add 289.6 kilograms (1.843 kilomol...

Embodiment 2

[0035] Add 228.4 kilograms (2.0 kilomoles) of 1,2-difluorobenzene, 382.4 kilograms (2.2 kilomoles) of trichloroacetyl chloride and 1600 kilograms of dichloroethane into the dry reactor, stir to dissolve, add anhydrous aluminum chloride 240 kg, a large amount of gas escaped, and the reaction temperature was controlled at 25-30°C under an ice-water bath. After the raw materials were completely reacted, the reaction liquid was poured into ice water under stirring, and 2093 kg of 3,4-difluoro- (α,α,α-Trichloroacetyl)benzene 493.0 kg (1.9 kilomole) dichloroethane solution, yield 95%.

[0036] Add 2093 kg of dichloroethane solution containing 493.0 kg (1.9 kilomole) of 3,4-difluoro-(α, α, α-trichloroacetyl)benzene in another reactor, and pass ammonia gas under stirring. Control the reaction temperature at 20-30°C, and a white solid precipitates out. After the reaction of the raw materials is complete, filter, wash, and dry to obtain 292.6 kg (1.862 kmol) of 3,4-difluorobenzamide, wi...

Embodiment 3

[0040] Add 228.4 kilograms (2.0 kilomoles) of 1,2-difluorobenzene, 382.4 kilograms (2.2 kilomoles) of trichloroacetyl chloride and 1600 kilograms of dichloroethane into the dry reactor, stir to dissolve, add anhydrous aluminum chloride 240 kg, a large amount of gas escapes, and the reaction temperature is controlled in an ice-water bath at 25-30°C. After the raw materials are completely reacted, the reaction solution is poured into ice water under stirring, and separated and washed to obtain 3,4-difluoro-( α, α, α-trichloroacetyl) benzene 493.0 kg (1.9 kilomoles), yield 95%.

[0041]Add 493.0 kg (1.9 kilomoles) of 3,4-difluoro-(α, α, α-trichloroacetyl)benzene and 1600 kg of chlorobenzene into another reactor, pass ammonia under stirring and control the reaction temperature to 20- At 30°C, a white solid precipitated out. After the raw materials were completely reacted, they were filtered, washed, and dried to obtain 292.6 kg (1.862 kmol) of 3,4-difluorobenzamide, with a yield o...

technical field

[0001] The invention belongs to the field of organic chemistry, and relates to a chemical raw material 3,4-difluorobenzonitrile, in particular to a new method for preparing 3,4-difluorobenzonitrile. Background technique

[0002] 3,4-Difluorobenzonitrile is a key intermediate in the synthesis of the phenoxypropionate herbicide cyhalofop-methyl. A variety of methods have been reported for the synthesis of 3,4-difluorobenzonitrile.

[0003] The methods using traditional synthesis techniques mainly include the following:

[0004] (l) Using 1,2-difluorobenzene as a raw material, it is synthesized through steps such as nitration, reduction, diazotization, and nitrilation. Since both 3,4-dichloronitrobenzene and 3,4-difluoroaniline Belong to carcinogen, cuprous cyanide raw material also belongs to highly poisonous, this law route is longer, and environmental pollution is serious.

[0005] (2) With 3,4-difluorobenzoic acid as raw material, it is prepared through a...

Examples

Embodiment 1

[0030] Add 228.4kg (2.0kmol) of 1,2-difluorobenzene, 382.4kg (2.2kmol) of trichloroacetyl chloride and 1600kg of dichloroethane into the dry reactor, stir to dissolve, add anhydrous zinc chloride 220 kg, a large amount of gas escaped, and the reaction temperature was controlled at 25-30°C under an ice-water bath. After the raw materials were completely reacted, the reaction liquid was poured into ice water under stirring, and 2093 kg containing 3,4-difluoro -(α,α,α-Trichloroacetyl)benzene 493.0 kg (1.9 kilomole) dichloroethane solution, yield 95%.

[0031] In another reactor, add 2093 kg of 3,4-difluoro-(α, α, α-trichloroacetyl) benzene 493.0 kg (1.9 kilomole) of dichloroethane solution, stir ammonia gas and control The reaction temperature is 20-30°C, and a white solid precipitates out. After the raw materials are completely reacted, filter, wash, and dry to obtain 289.6 kg (1.843 kmol) of 3,4-difluorobenzamide, with a yield of 97%

[0032] Add 289.6 kilograms (1.843 kilomol...

Embodiment 2

[0035] Add 228.4 kilograms (2.0 kilomoles) of 1,2-difluorobenzene, 382.4 kilograms (2.2 kilomoles) of trichloroacetyl chloride and 1600 kilograms of dichloroethane into the dry reactor, stir to dissolve, add anhydrous aluminum chloride 240 kg, a large amount of gas escaped, and the reaction temperature was controlled at 25-30°C under an ice-water bath. After the raw materials were completely reacted, the reaction liquid was poured into ice water under stirring, and 2093 kg of 3,4-difluoro- (α,α,α-Trichloroacetyl)benzene 493.0 kg (1.9 kilomole) dichloroethane solution, yield 95%.

[0036] Add 2093 kg of dichloroethane solution containing 493.0 kg (1.9 kilomole) of 3,4-difluoro-(α, α, α-trichloroacetyl)benzene in another reactor, and pass ammonia gas under stirring. Control the reaction temperature at 20-30°C, and a white solid precipitates out. After the reaction of the raw materials is complete, filter, wash, and dry to obtain 292.6 kg (1.862 kmol) of 3,4-difluorobenzamide, wi...

Embodiment 3

[0040] Add 228.4 kilograms (2.0 kilomoles) of 1,2-difluorobenzene, 382.4 kilograms (2.2 kilomoles) of trichloroacetyl chloride and 1600 kilograms of dichloroethane into the dry reactor, stir to dissolve, add anhydrous aluminum chloride 240 kg, a large amount of gas escapes, and the reaction temperature is controlled in an ice-water bath at 25-30°C. After the raw materials are completely reacted, the reaction solution is poured into ice water under stirring, and separated and washed to obtain 3,4-difluoro-( α, α, α-trichloroacetyl) benzene 493.0 kg (1.9 kilomoles), yield 95%.

[0041]Add 493.0 kg (1.9 kilomoles) of 3,4-difluoro-(α, α, α-trichloroacetyl)benzene and 1600 kg of chlorobenzene into another reactor, pass ammonia under stirring and control the reaction temperature to 20- At 30°C, a white solid precipitated out. After the raw materials were completely reacted, they were filtered, washed, and dried to obtain 292.6 kg (1.862 kmol) of 3,4-difluorobenzamide, with a yield o...

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