CN115872834A - Preparation method of 3,4, 5-trifluorobromobenzene - Google Patents
Preparation method of 3,4, 5-trifluorobromobenzene Download PDFInfo
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Abstract
The invention provides a preparation method of 3,4, 5-trifluorobromobenzene, which is characterized in that 2,3, 4-trifluoro-6-bromoaniline is used as a starting raw material, firstly the starting raw material is prepared into sulfate, and then the sulfate is sequentially subjected to diazotization and deamination to prepare the 3,4, 5-trifluorobromobenzene, wherein C containing alpha-H is used in the deamination 2～6 Alcohol as reducing agent, copper or copper salt as catalyst and water-insoluble organic solvent and water as reaction medium. The preparation method provided by the invention can avoid generating a large amount of phosphorus-containing wastewater, can effectively reduce the occurrence of side reactions in the deamination reaction process, greatly improves the yield and purity of the target product, and can reduce the pressure of the subsequent purification process. The preparation method provided by the invention is clean and environment-friendly, low in production cost, high in production efficiency and good in process safety, so that the preparation method is suitable for large-scale industrial production.
Description
Technical Field
The invention relates to the field of fine chemical intermediate preparation, and in particular relates to a preparation method of 3,4, 5-trifluorobromobenzene.
Background
3,4, 5-trifluorobromobenzene (also known as 1-bromo-3, 4, 5-trifluorobenzene, CAS number: 138526-69-9) is an important fine chemical intermediate, and especially in the fields of medicines, pesticides and the like, downstream products of the intermediate are very widely applied. Furthermore, 3,4, 5-trifluorobromobenzene is an important liquid crystal intermediate, and high-purity 3,4, 5-trifluorobromobenzene is the core for producing high-quality liquid crystal products.
At present, the synthesis process of 3,4, 5-trifluorobromobenzene mainly comprises the following steps:
(1) The method disclosed in Chinese patent CN 201310580913.0 uses 2,3, 4-trifluoroaniline as starting material, disperses the material in water, adds bromine drop by drop to brominate, and after-treatment obtains 2,3, 4-trifluoro-6-bromoaniline, then dissolves sodium nitrite in sulfuric acid, and adds sodium nitrite to obtain diazonium salt prepared by 2,3, 4-trifluoro-6-bromoaniline, then adds it to hypophosphorous acid and copper catalyst system to make diazo deamination, and finally after-treatment by steam distillation and rectification, etc. obtains 3,4, 5-trifluorobromobenzene.
The method uses a phosphorus-containing reagent during diazo deamination, generates a large amount of phosphorus-containing wastewater, is difficult to treat three wastes, is not in accordance with the safe and environment-friendly production concept always advocated by China, and has low yield of target products.
(2) The method disclosed in chinese patent CN 201510082492.8 uses 2,3,4-trifluoroaniline as starting material, and reacts with sulfuric acid in the presence of water and acetic acid to obtain 2,3,4-trifluoroaniline sulfate, then bromine is added to the sulfate, then hydrogen peroxide is added dropwise to react to obtain 2,3,4-trifluoro-6-bromoaniline sulfate, then sodium hypophosphite and copper salt are added to the mixture of 2,3,4-trifluoro-6-bromoaniline sulfate, then sodium nitrite aqueous solution is added dropwise at-5-0 ℃, and the reaction solution is rectified by layers to obtain 3,4,5-trifluorobromobenzene.
The method also uses a phosphorus-containing reagent, and repeated verification of a small test shows that more impurities subjected to hydrolysis and defluorination are generated in the reaction process, the yield cannot reach the reported yield, and because the boiling point of the impurities is very close to that of a target product, a high rectifying tower is required to separate the impurities, so that the energy consumption is high, and the operation is complex.
(3) The method disclosed in chinese patent CN 201810888990.5 uses 1,2, 3-trifluorobenzene as starting material, and disperses the starting material in a solvent, then adds sodium bromide aqueous solution containing buffer (sodium dihydrogen phosphate), then drops sodium hypochlorite solution for bromination, and removes the solvent from the organic phase to obtain crude 3,4, 5-trifluorobromobenzene, and finally performs melt crystallization on the crude product to obtain 3,4, 5-trifluorobromobenzene.
The method also uses a phosphorus-containing reagent, so phosphorus-containing wastewater which is difficult to treat is generated, and the generated isomer impurities are difficult to separate, and need to be melted and recrystallized at the low temperature of minus 20 ℃, so the method is difficult to industrialize.
(4) Non-patent literature (European Journal of Organic Chemistry, (3), 447-451, 2003) discloses a method in which 1,2,3-trifluorobenzene is used as a starting material, and lithium metallization is performed first to obtain an aryl lithium compound, and then bromination is performed to obtain the corresponding bromo-polyfluorobenzene.
The method needs strict control of anhydrous and oxygen-free reaction conditions, and has poor reaction regioselectivity, side reaction, more impurities in products and high raw material price.
(5) PCT patent WO 2017060905A1 discloses a method of mixing 3,4,5-trifluorobenzoic acid and bromoisocyanurate, then adding a mixed solution of bromine and trichlorobromomethane dropwise into the mixed solution at 120 ℃ under the irradiation of a 3W LED lamp, after reacting for 24 hours, adding sodium sulfite for neutralization, then adding anhydrous sodium sulfate for drying, filtering, and concentrating to obtain a final product.
The method has harsh conditions and high cost of the used raw materials, and is not suitable for large-scale production.
Based on the above situation, the existing preparation method of 3,4, 5-trifluorobromobenzene has many problems, especially problems of environmental pollution, non-ideal yield and the like, so that a new preparation method of 3,4, 5-trifluorobromobenzene is urgently needed to be found.
Disclosure of Invention
In order to make up for the defects in the prior art, the invention aims to provide the preparation method of the 3,4, 5-trifluorobromobenzene, the preparation method does not generate intractable phosphorus-containing wastewater, and the yield and the purity of the target product can be obviously improved.
The preparation method of 3,4, 5-trifluorobromobenzene provided by the invention uses 2,3, 4-trifluoro-6-bromoaniline as a starting material, firstly prepares the starting material into sulfate, and then prepares the 3,4, 5-trifluorobromobenzene through diazotization and deamination in sequence, wherein C containing alpha-H is used in the deamination 2～6 Alcohols as a reducing agent, copper or copper salt as a catalyst, and a mixed solvent consisting of an organic solvent which is not mutually soluble with water and water as a reaction medium.
In the preparation method provided by the invention, an acid water layer and an organic layer which are not mutually soluble are formed by a reaction medium, a diazonium salt product generated by diazotization reaction reacts with an inorganic catalyst in the acid water layer to generate a free radical intermediate, then the free radical intermediate is transferred to the organic layer through an organic solvent which is not mutually soluble with water, and the free radical intermediate is reduced into trifluorobromobenzene by an alcohol reducing agent in the organic layer, so that the side reaction of the free radical intermediate with water, hydrogen ions or other substances in the acid water layer is avoided, impurities such as a hydrolysate, a defluorinated product and the like are avoided (the reaction mechanism is shown in the specification), and simultaneously, the impurities generated by unstable decomposition of the diazonium salt in a reaction system are reduced, and the potential safety risk is reduced, therefore, the preparation method provided by the invention can obviously improve the purity and yield of a target product.
In addition, compared with the existing hypophosphorous acid reduction process, the preparation method provided by the invention can avoid the generation of a large amount of phosphorus-containing wastewater, is simpler in three-waste treatment and environment-friendly, and conforms to the production concept of safety and environmental protection advocated by the state. Due to the reduction of the content of impurities, the preparation method can also obviously reduce the pressure of the subsequent purification process, does not need complicated equipment such as a rectifying tower with high separation degree and the like, and does not need high energy consumption, thereby greatly reducing the comprehensive production cost.
In some embodiments of the preparation method according to the present invention, the deamination reaction may include the following processes: the reducing agent, the catalyst, and the reaction medium are mixed to form a mixed solution (for example, mixed in any order to form a mixed solution), and then the diazonium salt product after the diazotization reaction is added to the mixed solution, so that it is ensured that the radical intermediate is immediately transferred to the organic layer once generated, and the occurrence of side reactions is reduced. In some preferred embodiments, the temperature at which the diazonium salt product is added may be from 20 to 30 ℃. In some more preferred embodiments, the diazonium salt product may be added to the mixed liquor in a dropwise manner, and the time for dropwise addition may be 1 to 5 hours.
The reducing agent can be generalized alcohol, the molecular structure of the reducing agent only contains alpha-H and hydroxyl, and the reducing agent can also comprise substances such as formic acid, glucose and the like besides common alcohol. In some embodiments of the preparation method according to the present invention, the reducing agent may be alpha-H-containing C 2～6 A saturated aliphatic monohydric alcohol. In some preferred embodiments, the reducing agent may be an alpha-H containing C 2～4 Saturated aliphaticMonohydric alcohols, including but not limited to one or more of ethanol, propanol, isopropanol, n-butanol. In some more preferred embodiments, the reducing agent may be ethanol, isopropanol, or a mixture of the two in any ratio. In some most preferred embodiments, the reducing agent may be isopropanol.
In some embodiments of the preparation method according to the present invention, the molar ratio of the reducing agent to the 2,3, 4-trifluoro-6-bromoaniline may be 1.0 to 3.0: 1. In some preferred embodiments, the molar ratio of the reducing agent to the 2,3, 4-trifluoro-6-bromoaniline may be from 1.1 to 2.0: 1, including, but not limited to, molar ratios of about 1.1: 1, about 1.2: 1, about 1.3: 1, about 1.4: 1, about 1.5: 1, about 1.6: 1, about 1.7: 1, about 1.8: 1, about 1.9: 1, about 2.0: 1, or any combination of molar ratio intervals.
In some embodiments of the preparation method according to the present invention, the water-immiscible organic solvent may be a conventionally used water-immiscible aromatic hydrocarbon, alkane, halogenated aromatic hydrocarbon, halogenated alkane, ether or ester solvent. In some preferred embodiments, the water-immiscible organic solvent may be C 4～10 Alkane solvent of (2), C 6～10 Halogenated aromatic hydrocarbon solvent or C 1～4 Wherein the halogenated atoms may be one or more of F, cl and Br. In some more preferred embodiments, the water immiscible organic solvent includes, but is not limited to, one or more of heptane, n-hexane, petroleum ether, chlorobenzene, o-dichlorobenzene, p-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, toluene, xylene, dichloromethane, dichloroethane, tetrachloroethylene, methyl tert-butyl ether, ethyl acetate. In some further preferred embodiments, the water-immiscible organic solvent can be heptane or dichloromethane, which, upon formation of the reaction medium with water, results in a higher reaction yield with fewer impurities.
In some embodiments of the preparation method according to the present invention, the mass ratio of the water-immiscible organic solvent to water may be 0.5 to 2.0: 1. In some preferred embodiments, the mass ratio of the water-immiscible organic solvent to water can be from 0.8 to 1.2: 1, including but not limited to a mass ratio of about 0.8: 1, about 0.9: 1, about 1.0: 1, about 1.1: 1, about 1.2: 1, or any combination of mass ratio intervals.
In some embodiments of the preparation method according to the present invention, the catalyst may be a copper-based catalyst commonly used in the art. In some preferred embodiments, the catalyst includes, but is not limited to, one or more of copper powder, cuprous chloride, cuprous oxide, cupric sulfate, cupric oxide. In some more preferred embodiments, copper powder may be used as the catalyst.
In some embodiments of the preparation method according to the present invention, the molar ratio of the catalyst to the 2,3, 4-trifluoro-6-bromoaniline may be 0.05 to 0.25: 1. In some preferred embodiments, the molar ratio of the catalyst to the 2,3, 4-trifluoro-6-bromoaniline may be from 0.08 to 0.15: 1, including but not limited to a molar ratio of about 0.08: 1, about 0.09: 1, about 0.10: 1, about 0.11: 1, about 0.12: 1, about 0.13: 1, about 0.14: 1, about 0.15: 1, or any combination of molar ratio intervals.
In some embodiments of the preparation method according to the present invention, the 2,3, 4-trifluoro-6-bromoaniline reacts with concentrated sulfuric acid to prepare the corresponding sulfate, wherein the mass concentration of the concentrated sulfuric acid may be between 95% and 98%, the molar ratio of the 2,3, 4-trifluoro-6-bromoaniline to the concentrated sulfuric acid may be 1: 2.0-4.0, and the sulfate obtained by too little concentrated sulfuric acid is easy to agglomerate, so in some preferred embodiments, the molar ratio of the 2,3, 4-trifluoro-6-bromoaniline to the concentrated sulfuric acid may preferably be 1:3.0 to 3.5. In other preferred embodiments, the reaction temperature of 2,3, 4-trifluoro-6-bromoaniline and concentrated sulfuric acid can be controlled between 70 ℃ and 75 ℃, and the 2,3, 4-trifluoro-6-bromoaniline is easy to stick to the wall when the temperature is too low.
In some embodiments of the preparation method according to the present invention, the diazotizing agent in the diazotization reaction may be selected from nitrosylsulfuric acid or sodium nitrite, and the molar ratio thereof to the 2,3, 4-trifluoro-6-bromoaniline may be 1.01 to 1.30: 1. In some preferred embodiments, the molar ratio of the diazotizing agent to the 2,3, 4-trifluoro-6-bromoaniline may be 1.01 to 1.05: 1, including but not limited to a molar ratio of about 1.01: 1, about 1.02: 1, about 1.03: 1, about 1.04: 1, about 1.05: 1, or any combination of molar ratio intervals.
In some embodiments of the preparation method according to the present invention, the reaction temperature of the diazotization reaction may be 20 to 25 ℃, and a temperature too high may easily decompose the diazonium salt, and a temperature too low may easily increase reaction impurities.
In some embodiments of the preparation method according to the present invention, the reaction temperature of the deamination reaction may be 20 to 30 ℃, and if the temperature is too high, the reaction speed is increased, but the yield is easily affected, and if the temperature is too low, the reaction speed is slower, and more impurities are easily generated. In some preferred embodiments, the reaction temperature of the deamination reaction may be 25 to 30 ℃.
In some embodiments of the preparation method according to the present invention, the preparation method may further comprise: and after the deamination reaction is finished, separating an organic layer, extracting a water layer by using an organic solvent, combining organic phases, washing by using water, concentrating, and distilling under reduced pressure to obtain the 3,4, 5-trifluorobromobenzene. Due to the reduction of the impurity content, the preparation method can purify the target product only by a simple purification process without complex equipment and high energy consumption. Wherein, the organic solvent used for extracting the water layer can also be aromatic hydrocarbon, alkane, halogenated alkane, ether or ester solvent which is not mutually soluble with water and is used conventionally, and can be the same as or different from the organic solvent used in the reaction medium.
According to the preparation method provided by the invention, the alcohol reducing agent, the copper catalyst and the mixed reaction medium of the organic solvent and water are adopted in the deamination reaction step, and phosphorus-containing reagents such as hypophosphorous acid and the like which are used traditionally are avoided, so that a large amount of phosphorus-containing wastewater can be avoided, and the preparation method accords with the concept of green chemistry. The preparation method provided by the invention can effectively reduce the occurrence of side reactions in the deamination reaction process, obviously reduce the impurity content, greatly improve the yield and purity of the target product, and simultaneously reduce the pressure of the subsequent purification process. Therefore, the preparation method provided by the invention is clean and environment-friendly, low in production cost, high in production efficiency and good in process safety, and is suitable for large-scale industrial production.
Detailed Description
The technical solution of the present invention is further described in detail with reference to the following specific examples.
The starting materials or reagents used in the examples of the present invention and comparative examples are all commercially available products unless otherwise specified.
The percentages used in the examples of the present invention and the comparative examples are mass percentages unless otherwise specified.
Example 1
Copper powder/isopropanol/heptane-water system
Diazotization into salt: adding 98% of H into a 1L four-mouth bottle 2 SO 4 322g (3.25 mol), 230.6g (1 mol) of 2,3, 4-trifluoro-6-bromoaniline is added dropwise at room temperature, and after the dropwise addition is finished, the temperature is raised to 70-75 ℃ and the temperature is preserved for 1h. After heat preservation, cooling to 20-25 ℃, dropwise adding 320.6g (1.02 mol) of 40% nitrosyl sulfuric acid at the temperature of 20-30 ℃, wherein the dropwise adding time is about 1h, and after the dropwise adding, preserving heat for 2h at 20-25 ℃. The temperature is reduced to 15-20 ℃ to obtain 873.0g of diazonium product.
And (3) deamination: 225g of water, 212.5g of heptane, 91.0g (1.5 mol) of isopropanol and 7.7g (0.12 mol) of copper powder are put into a 2L four-mouth bottle, the temperature is controlled to be 20-30 ℃, diazo is dripped, the internal temperature is controlled to be 25-30 ℃, dripping is finished about 2 hours, and the temperature is kept for 1 hour continuously after dripping is finished. After the reaction, the reaction solution was separated, the aqueous layer was extracted with 100g of heptane, the organic layers were combined, washed once with 100g of water, desolventized, and distilled under reduced pressure to give 206.2g of 3,4, 5-trifluoroaniline with a purity of 99.7% (GC) and a yield of 97.5%.
Example 2
Cuprous chloride/isopropanol/chlorobenzene-water system
Diazo salifying: prepared according to example 1.
And (3) deamination: 225g of water, 212.5g of chlorobenzene, 91.0g (1.5 mol) of isopropanol and 11.9g (0.12 mol) of cuprous chloride are put into a 2L four-mouth bottle, the temperature is controlled to be 20-30 ℃, 873.0g of diazo is dripped, the internal temperature is controlled to be 25-30 ℃, dripping is completed within about 2 hours, and the temperature is kept for 1 hour continuously after dripping is completed. After the reaction, the reaction mixture was separated, the aqueous layer was extracted with 100g of heptane, the organic layers were combined, washed once with 100g of water, desolventized, and distilled under reduced pressure to give 203.9g of 3,4, 5-trifluoroaniline with a purity of 99.6% (GC) and a yield of 96.2%.
Example 3
Cuprous oxide/isopropanol/heptane-water system
Diazotization into salt: prepared according to example 1.
And (3) deamination: 225g of water, 212.5g of heptane, 91.0g (1.5 mol) of isopropanol and 17.2g (0.12 mol) of cuprous oxide are put into a 2L four-mouth bottle, the temperature is controlled to be 20-30 ℃, 873.0g of diazo is dripped, the internal temperature is controlled to be 25-30 ℃, dripping is completed within 2 hours, and the temperature is kept for 1 hour continuously after dripping is completed. After the reaction, the reaction mixture was separated, the aqueous layer was extracted with 100g of heptane, the organic layers were combined, washed once with 100g of water, desolventized, and distilled under reduced pressure to give 202.9g of 3,4, 5-trifluoroaniline with a purity of 99.6% (GC) and a yield of 95.8%.
Example 4
Copper powder/isopropanol/dichloromethane-water system
Diazotization into salt: prepared according to example 1.
And (3) deamination: 225g of water, 212.5g of dichloromethane, 91.0g (1.5 mol) of isopropanol and 7.7g (0.12 mol) of copper powder are put into a 2L four-neck bottle, the temperature is controlled to be 20-30 ℃, 873.0g of diazo is dripped, the internal temperature is controlled to be 20-30 ℃, dripping is completed within about 2 hours, and the temperature is kept for 1 hour continuously after dripping is completed. After the reaction, the aqueous layer was extracted with 100g of heptane, the organic layers were combined, washed once with 100g of water, desolventized and distilled under reduced pressure to 201.2g of 3,4, 5-trifluoroaniline with a purity of 99.6% (GC) and a yield of 95.0%.
Comparative example 1
Copper powder/isopropyl alcohol/water system
Diazotization into salt: prepared according to example 1.
And (3) deamination: 225g of water, 91.0g (1.5 mol) of isopropanol and 7.7g (0.12 mol) of copper powder are put into a 2L four-mouth bottle, the temperature is controlled to be 20-30 ℃, 873.0g of diazo is dripped, the internal temperature is controlled to be 25-30 ℃, dripping is finished about 2 hours, and the temperature is kept for 1 hour continuously after dripping is finished. After the reaction, the reaction mixture was extracted with 100g of heptane, and the extract was washed once with 100g of water, desolventized and distilled under reduced pressure to give 93.3g of 3,4, 5-trifluoroaniline with a purity of 95.7% (GC) and a yield of 42.4%.
Comparative example 2
Copper powder/isopropanol/heptane system
Diazo salifying: prepared according to example 1.
And (2) deamination: 212.5g of heptane, 91.0g (1.5 mol) of isopropanol and 7.7g (0.12 mol) of copper powder are put into a 2L four-neck bottle, the temperature is controlled to be 20-30 ℃, 873.0g of diazo is dripped, the internal temperature is controlled to be 25-30 ℃, dripping is completed within about 2 hours, and the temperature is kept for 1 hour continuously after dripping is completed. After the reaction, 225g of water was added, followed by liquid separation under stirring, the aqueous layer was extracted with 100g of heptane, the organic layers were combined, washed once with 100g of water, desolventized, and distilled under reduced pressure to obtain 77.9g of 3,4, 5-trifluoroaniline with a purity of 95.5% (GC) and a yield of 35.4%.
Comparative example 3
Example 1 of Chinese patent CN 201510082492.8 is repeated to obtain 180.2g of 3,4,5-trifluorobromobenzene with purity of 97.3% and yield of 82.9%.
As can be seen from the above examples and comparative examples, in the existing 3,4, 5-trifluorobromobenzene preparation method (such as comparative example 3), the process is complicated, the yield is not ideal, and a large amount of phosphorus-containing wastewater which is difficult to treat is generated. The preparation method provided by the invention obviously improves the production efficiency of the 3,4, 5-trifluorobromobenzene by effectively combining the reducing agent, the catalyst and the reaction medium, and does not generate phosphorus-containing wastewater.
Unless otherwise defined, all terms used herein have the meanings commonly understood by those skilled in the art.
The described embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention, and various other substitutions, alterations, and modifications may be made by those skilled in the art within the scope of the present invention.
Claims (10)
1. A method for preparing 3,4, 5-trifluorobromobenzene uses 2,3, 4-trifluoro-6-bromoaniline as starting material, firstly prepares the 2,3, 4-trifluoro-6-bromoaniline as sulfate, and then prepares the 3,4, 5-trifluorobromobenzene by diazotization and deamination in sequence, and is characterized in that C containing alpha-H is used in the deamination 2～6 Alcohols as reducing agents, copperOr copper salt as catalyst and the mixed solvent of water and organic solvent immiscible with water as reaction medium.
2. The method according to claim 1, wherein the reducing agent is C containing α -H 2～6 Saturated aliphatic monohydric alcohols, preferably C 2～4 Saturated aliphatic monohydric alcohols, more preferably ethanol and/or isopropanol.
3. The method according to claim 2, wherein the molar ratio of the reducing agent to the 2,3, 4-trifluoro-6-bromoaniline is 1.0-3.0: 1, preferably 1.1-2.0: 1.
4. The process according to any one of claims 1 to 3, wherein the water-immiscible organic solvent is selected from aromatic hydrocarbons, alkanes, halogenated aromatic hydrocarbons, halogenated alkanes, ethers or esters, preferably C 4～10 Preferably a halogenated aromatic hydrocarbon solvent of C 6～10 The halogenated alkane solvent is preferably C 1～4 A haloalkane hydrocarbon solvent of (a); preferably, the water-immiscible organic solvent is selected from one or more of heptane, n-hexane, petroleum ether, chlorobenzene, o-dichlorobenzene, p-dichlorobenzene, m-dichlorobenzene, trichlorobenzene, toluene, xylene, dichloromethane, dichloroethane, tetrachloroethylene, methyl tert-butyl ether, ethyl acetate.
5. The method according to claim 4, wherein the mass ratio of the water-immiscible organic solvent to water is 0.5-2.0: 1, preferably 0.8-1.2: 1.
6. The method according to any one of claims 1 to 5, wherein the copper salt is selected from one or more of cuprous chloride, cuprous oxide, cupric sulfate, cupric oxide; and/or
The molar ratio of the catalyst to the 2,3, 4-trifluoro-6-bromoaniline is 0.05-0.25: 1, preferably 0.08-0.15: 1.
7. The method according to any one of claims 1 to 6, wherein the 2,3, 4-trifluoro-6-bromoaniline is reacted with concentrated sulfuric acid having a mass concentration of 95 to 98% to produce sulfate, and the molar ratio of the 2,3, 4-trifluoro-6-bromoaniline to the concentrated sulfuric acid is 1: 2.0 to 4.0, preferably 1:3.0 to 3.5.
8. The process according to any one of claims 1 to 7, wherein in the diazotization reaction, the diazotizing agent is selected from nitrosylsulfuric acid or sodium nitrite, and the molar ratio of the diazotizing agent to the 2,3, 4-trifluoro-6-bromoaniline is 1.01 to 1.30: 1, preferably 1.01 to 1.05: 1.
9. The method according to any one of claims 1 to 8, wherein the reaction temperature of the diazotization reaction is 20 to 25 ℃; and/or
The reaction temperature of the deamination reaction is 20-30 ℃, preferably 25-30 ℃.
10. The production method according to any one of claims 1 to 9, characterized by further comprising: and after the deamination reaction is finished, separating an organic layer, extracting a water layer by using an organic solvent, combining organic phases, washing by water, concentrating, and then carrying out reduced pressure distillation to obtain the 3,4, 5-trifluorobromobenzene.
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