CN113754512A - Preparation method of o-bromobenzotrifluoride - Google Patents
Preparation method of o-bromobenzotrifluoride Download PDFInfo
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- CN113754512A CN113754512A CN202111013678.XA CN202111013678A CN113754512A CN 113754512 A CN113754512 A CN 113754512A CN 202111013678 A CN202111013678 A CN 202111013678A CN 113754512 A CN113754512 A CN 113754512A
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- hydrobromic acid
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- trifluoromethylaniline
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- sodium nitrite
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- RWXUNIMBRXGNEP-UHFFFAOYSA-N 1-bromo-2-(trifluoromethyl)benzene Chemical compound FC(F)(F)C1=CC=CC=C1Br RWXUNIMBRXGNEP-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 238000002360 preparation method Methods 0.000 title claims abstract description 13
- BMYNFMYTOJXKLE-UHFFFAOYSA-N 3-azaniumyl-2-hydroxypropanoate Chemical compound NCC(O)C(O)=O BMYNFMYTOJXKLE-UHFFFAOYSA-N 0.000 claims abstract description 89
- 239000000243 solution Substances 0.000 claims abstract description 85
- 238000006243 chemical reaction Methods 0.000 claims abstract description 65
- LPXPTNMVRIOKMN-UHFFFAOYSA-M sodium nitrite Chemical compound [Na+].[O-]N=O LPXPTNMVRIOKMN-UHFFFAOYSA-M 0.000 claims abstract description 60
- VBLXCTYLWZJBKA-UHFFFAOYSA-N 2-(trifluoromethyl)aniline Chemical compound NC1=CC=CC=C1C(F)(F)F VBLXCTYLWZJBKA-UHFFFAOYSA-N 0.000 claims abstract description 57
- CPELXLSAUQHCOX-UHFFFAOYSA-N Hydrogen bromide Chemical compound Br CPELXLSAUQHCOX-UHFFFAOYSA-N 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 31
- 235000010288 sodium nitrite Nutrition 0.000 claims abstract description 30
- 229910021589 Copper(I) bromide Inorganic materials 0.000 claims abstract description 27
- NKNDPYCGAZPOFS-UHFFFAOYSA-M copper(i) bromide Chemical compound Br[Cu] NKNDPYCGAZPOFS-UHFFFAOYSA-M 0.000 claims abstract description 27
- 238000002156 mixing Methods 0.000 claims abstract description 22
- 229910000042 hydrogen bromide Inorganic materials 0.000 claims abstract description 19
- 239000012954 diazonium Substances 0.000 claims abstract description 13
- 150000001989 diazonium salts Chemical class 0.000 claims abstract description 13
- 239000012295 chemical reaction liquid Substances 0.000 claims abstract description 7
- 238000004519 manufacturing process Methods 0.000 claims description 14
- 239000011259 mixed solution Substances 0.000 claims description 13
- 230000003068 static effect Effects 0.000 claims description 13
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 239000007788 liquid Substances 0.000 claims description 11
- 239000002904 solvent Substances 0.000 claims description 10
- 238000005406 washing Methods 0.000 claims description 10
- 238000000926 separation method Methods 0.000 claims description 9
- 239000007789 gas Substances 0.000 claims description 5
- 239000003513 alkali Substances 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 3
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 2
- 230000006837 decompression Effects 0.000 claims description 2
- 239000008096 xylene Substances 0.000 claims description 2
- 238000006193 diazotization reaction Methods 0.000 abstract description 9
- 238000005893 bromination reaction Methods 0.000 abstract description 8
- 230000031709 bromination Effects 0.000 abstract description 3
- 150000003839 salts Chemical class 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 238000010923 batch production Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000002994 raw material Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000012043 crude product Substances 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000004880 explosion Methods 0.000 description 2
- 238000010606 normalization Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000010812 external standard method Methods 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- SLFVYFOEHHLHDW-UHFFFAOYSA-N n-(trifluoromethyl)aniline Chemical compound FC(F)(F)NC1=CC=CC=C1 SLFVYFOEHHLHDW-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012074 organic phase Substances 0.000 description 1
- 239000000575 pesticide Substances 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011343 solid material Substances 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000007966 viscous suspension Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C245/00—Compounds containing chains of at least two nitrogen atoms with at least one nitrogen-to-nitrogen multiple bond
- C07C245/20—Diazonium compounds
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/093—Preparation of halogenated hydrocarbons by replacement by halogens
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention discloses a preparation method of o-bromobenzotrifluoride, which comprises the following steps: sequentially introducing first hydrobromic acid, a sodium nitrite solution and a reaction solution A into a continuous flow reactor, and carrying out a mixed reaction to obtain a diazonium salt solution; the reaction liquid A is obtained by mixing and reacting second hydrobromic acid and an o-trifluoromethylaniline solution; the mass percentage of hydrogen bromide in the second hydrobromic acid is 20-40%; the molar ratio of the hydrogen bromide in the second hydrobromic acid to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is (4-15): 1; and mixing the diazonium salt solution with cuprous bromide and third hydrobromic acid for reaction. The invention adopts the process of serial connection of continuous flow diazotization and intermittent bromination, and optimizes reaction parameters to continuously carry out diazotization and bromination, and the reaction yield is not lower than the level of the existing intermittent process.
Description
Technical Field
The invention relates to a preparation method of o-bromobenzotrifluoride.
Background
O-bromotrifluorotoluene, also known as 2-bromotrifluorotoluene, is water white or pale yellow liquid and is an important pesticide and medical intermediate. With the continuous expansion of the application, the market demand is also expanded.
O-trifluoromethylaniline is a byproduct of a trifluoromethylaniline production line, and the purity of the o-trifluoromethylaniline reaches 99.5 percent, but the o-trifluoromethylaniline has small application range, small market demand and low price. By using o-trifluoromethylaniline as a raw material, o-bromobenzotrifluoride having a higher commercial value can be prepared.
At present, the production of o-bromobenzotrifluoride is mainly carried out in a batch reactor, but the batch process has long feeding and discharging time, the reaction time is hour-level, and the production efficiency is low. In addition, the production of o-bromotrifluorotoluene can be subjected to a diazotization process, the process belongs to a dangerous chemical process which is mainly regulated by the state, when the process is carried out in an intermittent reaction kettle, the volume of the reactor is generally large, the temperature control accuracy is low, and the material proportioning accuracy is low, so that the diazotization reaction is violent, the heat release is large, the problem of easy explosion exists, a large amount of toxic and explosive gas can be generated sometimes, and a fire disaster is caused, and the process has a large safety risk.
In order to overcome the above-mentioned disadvantages of the batch reactor in the production of ortho-bromotrifluorotoluene, a continuous flow reactor may be considered. However, for the continuous flow reactor, the reaction raw materials are all fluid, and the generation of solid is not allowed, otherwise, the equipment is blocked, and the reaction cannot be normally carried out. In fact, salt precipitation easily occurs in the production process of o-bromobenzotrifluoride, which hinders the application of the continuous flow reactor in the reaction system.
It is therefore of great importance to develop a preparation process that allows the production of ortho-bromobenzotrifluoride to proceed normally in a continuous flow reactor.
Disclosure of Invention
The invention aims to solve the technical problem that in the prior art, the preparation of the o-bromobenzotrifluoride generally adopts a batch kettle type reaction, and the risk of severe diazotization reaction, easy explosion and the like exists, and provides a continuous flow method for producing the o-bromobenzotrifluoride.
In the research process, the applicant of the invention finds that salt precipitation is easily generated in the continuous flow reaction process and blocks the continuous flow reactor if the kettle type reaction of the o-bromobenzotrifluoride is simply adjusted to the continuous flow reaction, so that the production cannot be normally carried out in the continuous flow reactor.
The inventor creatively adopts the process of serial connection of continuous flow diazotization and intermittent bromination through a large number of experiments, and optimizes the raw material proportion, the salt-forming reaction temperature, the feeding sequence and the reaction conditions, so that the salt-forming reaction and the diazotization reaction can be continuously carried out, the concept that the continuous flow reaction can not be carried out on solid materials is broken through, and the reaction yield is not lower than the existing intermittent process level.
The invention solves the technical problems through the following technical scheme:
the preparation method of the o-bromotrifluorotoluene comprises the following steps:
(1) sequentially introducing first hydrobromic acid, a sodium nitrite solution and a reaction solution A into a continuous flow reactor, and carrying out a mixed reaction to obtain a diazonium salt solution;
the reaction liquid A is obtained by mixing and reacting second hydrobromic acid and an o-trifluoromethylaniline solution; the temperature of the mixed reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution is 25-35 ℃;
the mass percentage of hydrogen bromide in the second hydrobromic acid is 20-40%; the molar ratio of the hydrogen bromide in the second hydrobromic acid to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is (4-15): 1;
(2) and mixing the diazonium salt solution with cuprous bromide and third hydrobromic acid for reaction.
Generally, hydrobromic acid and o-trifluoromethylaniline are mixed to easily form salt, form viscous suspension and cannot enter the continuous flow reactor, and the inventors of the present invention surprisingly found that the continuous flow reactor can be effectively prevented from being blocked at 10 ℃ to 35 ℃ by setting the concentration of the second hydrobromic acid, the molar ratio of hydrogen bromide in the second hydrobromic acid to o-trifluoromethylaniline in the o-trifluoromethylaniline solution, the temperature of the mixing reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution, and the feeding sequence.
In the present invention, preferably, in step (1), the second hydrobromic acid enters the continuous flow reactor through a heater.
In the present invention, preferably, in step (1), the o-trifluoromethylaniline solution enters the continuous flow reactor after passing through a heater.
In the present invention, in the step (1), the temperature of the second hydrobromic acid is preferably 25 to 35 ℃.
In the present invention, preferably, in the step (1), the temperature of the o-trifluoromethylaniline solution is 25 to 35 ℃.
In the present invention, preferably, in step (1), the second hydrobromic acid passes through the heater and enters a static mixer, and then enters the continuous flow reactor.
In the present invention, preferably, in step (1), the o-trifluoromethylaniline solution enters a static mixer after passing through a heater, and then enters the continuous flow reactor.
In the present invention, preferably, in the step (1), the mixing reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution is performed in the static mixer.
Preferably, in step (1), the molar ratio of the hydrogen bromide in the second hydrobromic acid to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is 7.5:1.
preferably, in step (1), the molar ratios of the hydrogen bromide in the second hydrobromic acid, the sodium nitrite in the sodium nitrite solution and the o-trifluoromethylaniline in the o-trifluoromethylaniline solution are (4-15): (1-1.08): 1, more preferably 7.5:1.05: 1.
Preferably, in step (1), the mass percent and flow rate of hydrogen bromide in the first hydrobromic acid and the second hydrobromic acid are the same.
Preferably, in step (1), the mass percentages of hydrogen bromide in the first hydrobromic acid and the second hydrobromic acid are both 25%.
Preferably, in step (1), the flow rates of the first hydrobromic acid and the second hydrobromic acid are 3400 g/h-7000 g/h, such as 4796 g/h.
Preferably, in step (1), the flow rate ratio of the first hydrobromic acid and the second hydrobromic acid to the sodium nitrite solution is (4.9-10.7): 1.
in the present invention, in step (1), the solvent of the sodium nitrite solution is preferably water.
Preferably, in the step (1), the mass percentage of the sodium nitrite in the sodium nitrite solution is 10 to 40%, and more preferably 30%.
In the present invention, in step (1), the solvent of the o-trifluoromethylaniline solution is preferably toluene and/or xylene.
Preferably, the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is 30 to 60% by mass, and more preferably 44.4% by mass.
Preferably, in the step (1), the feeding flow rate of the o-trifluoromethylaniline solution is 500-1000 g/h, such as 700 g/h.
In the present invention, in the step (1), the flow rate ratio of the o-trifluoromethylaniline solution to the sodium nitrite solution is preferably (1.7-2.3): 1.
In the present invention, preferably, in step (1), when the first hydrobromic acid and the sodium nitrite solution generate a reddish brown gas, the reaction solution a is introduced to perform a mixing reaction.
In the present invention, preferably, in step (1), the continuous flow reactor is one or more of a static mixer, a microchannel reactor or a tubular reactor, and more preferably, a microchannel reactor. Those skilled in the art will appreciate that a continuous reaction system may be formed by connecting in parallel one or more of the continuous flow reactors described above, depending on the scale of production.
In the present invention, in the step (1), the temperature of the mixing reaction of the sodium nitrite solution and the reaction solution a is preferably-10 to 10 ℃, and more preferably-5 to 0 ℃.
In the present invention, in the step (1), the time for the mixing reaction of the sodium nitrite solution and the reaction solution a is preferably 1 to 30 seconds, for example, 6 seconds.
In the present invention, preferably, in the step (1), the pressure of the mixing reaction of the sodium nitrite solution and the reaction liquid a is 0.1 to 0.3MPa, for example, 0.15 MPa; the pressure is known to those skilled in the art as gauge pressure.
In the present invention, preferably, in the step (1), the preparation method of o-bromotrifluorotoluene further includes performing liquid separation treatment on the diazonium salt solution.
In the present invention, in step (1), preferably, the solvent of the first hydrobromic acid and the solvent of the second hydrobromic acid are both water.
The liquid separation treatment may be conventional in the art. The liquid separation treatment is used to remove the organic phase of the diazonium salt solution.
In the present invention, preferably, in the step (2), the cuprous bromide and the third hydrobromic acid are present in the form of a mixed solution.
Preferably, in the step (2), when the cuprous bromide and the third hydrobromic acid exist in the form of a mixed solution, the solvent of the mixed solution of the cuprous bromide and the third hydrobromic acid is water.
Preferably, in the step (2), the mass percentage of the cuprous bromide in the mixed solution of the cuprous bromide and the third hydrobromic acid is 5% to 30%, and more preferably 16.7%.
In the present invention, the concentration of the third hydrobromic acid may be any concentration, and preferably, the mass percentage of hydrogen bromide in the third hydrobromic acid may be 0 to 48%; in the case of 0, the reaction yield and the reaction rate are slightly lowered, but the essence of the improvement of the present invention is not affected. Preferably, in the step (2), the mass percentage of hydrogen bromide in the mixed solution of cuprous bromide and the third hydrobromic acid is 40% to 48%, and more preferably 48%.
In the present invention, in the step (2), the temperature of the mixing reaction is preferably 30 to 50 ℃, and more preferably 40 ℃.
In the present invention, it is preferable that in the step (2), the pressure of the mixing reaction is-20 kPa to 10kPa, more preferably-10 kPa; the pressure is known to those skilled in the art as gauge pressure.
In the present invention, in the step (2), the molar ratio of the cuprous bromide to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is preferably (0.1 to 1):1, and more preferably 0.21. The amount of cuprous bromide used will affect the yield and purity of ortho-bromotrifluorotoluene.
In the present invention, preferably, in the step (2), the mixing reaction is performed in a batch tank reactor.
In the present invention, preferably, in the step (2), the diazonium salt solution is introduced into the third hydrobromic acid and the cuprous bromide which are mixed in advance.
As known by persons skilled in the art, after the step (2), collecting a product at the outlet of the tank reactor for detection, and determining that the product is qualified.
In the present invention, preferably, the preparation method of o-bromotrifluorotoluene further comprises post-treatment operations of liquid separation, alkali washing, water washing, reduced pressure concentration and rectification in sequence.
The post-treatment operations of the liquid separation, the alkaline washing, the water washing, the vacuum concentration and the rectification can all be conventional in the art.
Through the liquid separation, alkali washing, water washing and decompression concentration post-treatment, the third hydrobromic acid and the cuprous bromide can be recycled for cyclic utilization; the ortho-bromobenzotrifluoride with high purity is obtained through the rectification operation.
On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.
The reagents and starting materials used in the present invention are commercially available.
The positive progress effects of the invention are as follows:
(1) according to the invention, by setting reaction conditions such as the concentration of the second hydrobromic acid, the ratio of the second hydrobromic acid to the o-trifluoromethylaniline, the temperature of the mixed reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution, the feeding sequence and the like, the blockage of the continuous flow reactor can be avoided, the normal operation of the production of the o-bromobenzotrifluoride in the continuous flow reactor can be realized, and the continuous operation of the reaction can be ensured.
(2) The method can obtain the o-bromobenzotrifluoride with the purity of 99.8 percent, the yield is 91.78 percent, the purity of the o-bromobenzotrifluoride prepared by the existing batch process is 99 percent, the yield is 91 percent, and the yield and the purity of the method are equivalent to the existing process level.
(3) The invention can realize the accurate input of materials by adopting a continuous reaction technology, further, the excellent mass transfer and heat transfer capacity of the microreactor can be utilized to quickly remove the reaction heat, the liquid holding volume in unit time is small, and the danger degree of the diazotization reaction is greatly reduced.
(4) The invention adopts a continuous reaction technology, can realize automation, avoids the consumption of batch process feeding and discharging time, further has the on-line reaction time of a micro-channel reactor of second level, greatly improves the reaction efficiency and simultaneously reduces the number of operators.
Drawings
FIG. 1 is a schematic flow diagram of the production process of the present invention;
reference numerals:
11 a first hydrobromic acid delivery pump, 12 a sodium nitrite solution delivery pump, 13 an o-trifluoromethylaniline solution delivery pump, and 14 a second hydrobromic acid delivery pump; 21 a first heater, 22 a second heater, 23 a third heater; 31 a first static mixer, 32 a second static mixer; 4, a micro-channel reactor; 5 a batch type reaction kettle.
Detailed Description
The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.
In the following examples and comparative examples, the purity of o-bromotrifluorotoluene was determined by GC external standard method. The method specifically comprises the following steps: 1.0g of a sample was taken and diluted to 50ml with methanol, and analyzed by GC, and the content of each substance was quantified by the area normalization method. GC instrument model: agilent 7820A; the type of the chromatographic column: DB-1701(30m 320um 0.25 um); carrier gas high purity nitrogen (0.9999); a detector: a FID detector; flow rate of hydrogen: 30 ml/min; air: 300 ml/min; nitrogen gas: 1.0 ml/min; the split ratio is as follows: 30: 1; tail-blow flow: 25 ml/min; temperature column temperature: keeping at 80 deg.C for 2min, and increasing to 260 deg.C at a rate of 30 deg.C/min for 2 min; the gasification temperature: 250 ℃; detector temperature: 300 ℃; the calculation method is a peak area normalization method.
Example 1
Combining the process shown in the figure 1, preparing a cuprous bromide/third hydrobromic acid mixed solution in a batch type reaction kettle 5, wherein the cuprous bromide accounts for 16.7% (wt), the hydrogen bromide accounts for 48% (wt), and the temperature is controlled to 40 ℃ for standby;
respectively preparing 44.4 percent (wt) o-trifluoromethylaniline/toluene solution, 25 percent (wt) hydrobromic acid and 30 percent (wt) sodium nitrite solution in a preparation kettle for later use.
Starting a 25% (wt) first hydrobromic acid delivery pump 11, preheating to 35 ℃ by a first heater 21, feeding the first hydrobromic acid into a microchannel reactor 4 by a static mixer 31, and controlling the temperature of the microchannel reactor 4 to be-5-0 ℃; after 25 percent (wt) of first hydrobromic acid flows out of the microchannel reactor 4, starting a 30 percent (wt) sodium nitrite solution delivery pump 12, feeding the microchannel reactor 4, and controlling the temperature of the microchannel reactor 4 to be-5-0 ℃; after the outlet of the microchannel reactor 4 generates the reddish brown gas, a 44.4% (wt) o-trifluoromethylaniline/toluene solution delivery pump 13 is started, the red brown gas is preheated to 35 ℃ by a second heater 22, and then enters a static mixer 32 to carry out a salt forming reaction with the second hydrobromic acid which is delivered by a second hydrobromic acid delivery pump 14 and preheated by a third heater 23, the temperature of the static mixer 32 is controlled to be 25-35 ℃ during the salt forming reaction, the salified material enters the microchannel reactor 4 to carry out a diazotization reaction, and the temperature of the microchannel reactor 4 is controlled to be-5-0 ℃.
In the practical operation process, the pipelines of the first hydrobromic acid and the second hydrobromic acid can be combined into one for convenient operation, namely, two pipelines are combined into one.
After the system is stabilized, the outlet of the microchannel reactor 4 is connected into a batch reactor 5 in which a cuprous bromide (16.7 wt%)/third hydrobromic acid (48 wt%) mixed solution is positioned, so as to carry out bromination reaction, and the temperature of the bromination reaction is controlled to be 40 ℃. Wherein the molar ratio of cuprous bromide in the cuprous bromide (16.7 wt%)/third hydrobromic acid (48 wt%) mixed solution to o-trifluoromethylaniline in the o-trifluoromethylaniline solution is 0.21: 1.
After the diazonium salt solution in the batch reaction kettle 5 is added with a specified amount, the outlet of the microchannel reactor 4 is connected into another batch reaction kettle with the same load, and the reaction is kept to be continuously carried out.
Wherein the flow rate of the first hydrobromic acid and the second hydrobromic acid is 4796 g/h; the flow rate of the sodium nitrite solution is 447 g/h; the feeding flow rate of the o-trifluoromethylaniline solution is 700 g/h; the time of the mixing reaction of the sodium nitrite solution and the reaction liquid A is 6s, and the pressure is 0.15 MPa; the pressure of the bromination reaction was-10 kPa.
And (3) carrying out bromination reaction in a batch type reaction kettle 5 which is connected with a specified amount of diazonium salt, and continuously stirring and preserving heat until the detection is qualified by central control.
And (4) carrying out liquid separation, alkali washing, water washing and reduced pressure concentration on the bromination reaction solution to obtain a crude product, and recycling the third hydrobromic acid and cuprous bromide for cyclic utilization.
Rectifying the crude product to obtain the final product 2-bromotrifluorotoluene, namely the o-bromotrifluorotoluene.
Examples 2 to 5 and comparative examples 1 to 3
The results are shown in Table 1 below, except for the data shown in the following table, which are similar to those of example 1.
TABLE 1
Claims (10)
1. The preparation method of o-bromotrifluorotoluene is characterized by comprising the following steps:
(1) sequentially introducing first hydrobromic acid, a sodium nitrite solution and a reaction solution A into a continuous flow reactor, and carrying out a mixed reaction to obtain a diazonium salt solution;
the reaction liquid A is obtained by mixing and reacting second hydrobromic acid and an o-trifluoromethylaniline solution; the temperature of the mixed reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution is 25-35 ℃;
the mass percentage of hydrogen bromide in the second hydrobromic acid is 20-40%; the molar ratio of the hydrogen bromide in the second hydrobromic acid to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is (4-15): 1;
(2) and mixing the diazonium salt solution with cuprous bromide and third hydrobromic acid for reaction.
2. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in the step (1), the second hydrobromic acid enters the continuous flow reactor through a heater;
in the step (1), the o-trifluoromethylaniline solution enters the continuous flow reactor through a heater;
in the step (1), the temperature of the second hydrobromic acid is 25-35 ℃;
in the step (1), the temperature of the o-trifluoromethylaniline solution is 25-35 ℃.
3. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in the step (1), the second hydrobromic acid enters a static mixer through a heater and then enters the continuous flow reactor;
in the step (1), the o-trifluoromethylaniline solution enters a static mixer after passing through a heater and then enters the continuous flow reactor.
4. The method for producing ortho-bromotrifluorotoluene according to claim 3, wherein the method for producing ortho-bromotrifluorotoluene satisfies one or more of the following conditions:
in the step (1), the mixing reaction of the second hydrobromic acid and the o-trifluoromethylaniline solution is carried out in the static mixer.
5. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in step (1), the mass percent and flow rate of hydrogen bromide in the first hydrobromic acid and the second hydrobromic acid are the same;
in step (1), the solvent of the first hydrobromic acid and the solvent of the second hydrobromic acid are both water.
6. The method for preparing ortho-bromotrifluorotoluene according to claim 5, wherein the method for preparing ortho-bromotrifluorotoluene satisfies one or more of the following conditions:
in the step (1), the mass percentages of hydrogen bromide in the first hydrobromic acid and the second hydrobromic acid are both 25%;
in the step (1), the molar ratio of the hydrogen bromide in the second hydrobromic acid to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is 7.5: 1;
in the step (1), the molar ratio of hydrogen bromide in the second hydrobromic acid to sodium nitrite in the sodium nitrite solution to o-trifluoromethylaniline in the o-trifluoromethylaniline solution is (4-15): (1-1.08): 1, more preferably 7.5:1.05: 1;
in the step (1), the flow rates of the first hydrobromic acid and the second hydrobromic acid are 3400 g/h-7000 g/h, preferably 4796 g/h;
in the step (1), the flow rate ratio of the first hydrobromic acid to the second hydrobromic acid to the sodium nitrite solution is (4.9-10.7): 1.
7. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in the step (1), the solvent of the sodium nitrite solution is water;
in the step (1), the mass percent of sodium nitrite in the sodium nitrite solution is 10-40%, and more preferably 30%;
in the step (1), the solvent of the o-trifluoromethylaniline solution is toluene and/or xylene;
in the step (1), the mass percent of the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is 30-60%, and preferably 44.4%;
in the step (1), the feeding flow rate of the o-trifluoromethylaniline solution is 500-1000 g/h;
in the step (1), the flow rate ratio of the o-trifluoromethylaniline solution to the sodium nitrite solution is (1.7-2.3): 1.
8. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in the step (1), when the first hydrobromic acid and the sodium nitrite solution generate reddish brown gas, introducing the reaction liquid A;
in step (1), the continuous flow reactor is one or more of a static mixer, a microchannel reactor or a tubular reactor, and is preferably a microchannel reactor;
in the step (1), the temperature of the mixed reaction of the sodium nitrite solution and the reaction solution A is-10 to 10 ℃, and is more preferably-5 to 0 ℃;
in the step (1), the mixing reaction time of the sodium nitrite solution and the reaction liquid A is 1-30 s, such as 6 s;
in the step (1), the pressure of the mixing reaction of the sodium nitrite solution and the reaction solution A is 0.1-0.3MPa, such as 0.15 MPa;
in the step (1), the preparation method of o-bromotrifluorotoluene further comprises liquid separation treatment of the diazonium salt solution.
9. The method according to claim 1, wherein the method satisfies one or more of the following conditions:
in the step (2), the cuprous bromide and the third hydrobromic acid exist in the form of a mixed solution;
in the step (2), the temperature of the mixing reaction is 30-50 ℃, and is preferably 40 ℃;
in the step (2), the pressure of the mixing reaction is-20 kPa to 10kPa, and is more preferably-10 kPa;
in the step (2), the molar ratio of the cuprous bromide to the o-trifluoromethylaniline in the o-trifluoromethylaniline solution is (0.1-1): 1, more preferably 0.21;
in the step (2), the mixing reaction is carried out in a batch kettle type reactor;
in the step (2), the diazonium salt solution is introduced into the third hydrobromic acid and the cuprous bromide which are mixed in advance;
the preparation method of the o-bromotrifluorotoluene also sequentially comprises the post-treatment operations of liquid separation, alkali washing, water washing, decompression concentration and rectification.
10. The method of producing ortho-bromotrifluorotoluene according to claim 9, wherein the method of producing ortho-bromotrifluorotoluene satisfies one or more of the following conditions:
when the cuprous bromide and the third hydrobromic acid exist in the form of a mixed solution, the solvent of the mixed solution of the cuprous bromide and the third hydrobromic acid is water;
in the mixed solution of the cuprous bromide and the third hydrobromic acid, the mass percent of the cuprous bromide is 5-30%, and more preferably 16.7%;
in the mixed solution of the cuprous bromide and the third hydrobromic acid, the mass percentage of hydrogen bromide is 40-48%, and more preferably 48%.
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