CN115232010A - Method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction - Google Patents
Method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction Download PDFInfo
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Abstract
The invention discloses a method for preparing 1-fluoro-4-nitronaphthalene by a microchannel reaction, which comprises the following steps: mixing 1-fluoronaphthalene with a first organic solvent to prepare a raw material solution; mixing nitric acid and sulfuric acid to prepare a nitrifying liquid; respectively pumping the raw material liquid and the nitrifying liquid into a microchannel reactor for reaction to obtain reaction liquid; separating the reaction solution through a liquid separation tank to obtain a waste acid solution and an organic phase; and adding the concentrated organic phase into a second organic solvent for recrystallization to obtain the target product. The invention uses the microchannel reactor to realize uniform and efficient heat exchange in the reaction process, and improves the safety of preparing the 1-fluoro-4-nitronaphthalene.
Description
Technical Field
The invention relates to the technical field of chemical synthesis, in particular to a method for preparing 1-fluoro-4-nitronaphthalene through a microchannel reaction.
Background
Currently, the synthesis of 1-fluoro-4-nitronaphthalene mainly comprises three methods: electrochemical nitration, acetic acid-nitric acid nitration, sulfuric acid-nitric acid nitration.
In the electrochemical nitration method, acetonitrile is used as solvent and lithium tetrafluoroborate is used as electrolyte in the preparation process, and 1-fluoronaphthalene and nitrous acid are addedAdding isoamyl ester into the anode chamber at a current density of 10A/cm 2 The reaction is carried out under the condition of (1) to obtain a mixture of 4-nitro-1-fluoronaphthalene and 8-nitro-1-fluoronaphthalene, and 42 percent of 4-nitro-1-fluoronaphthalene and 28 percent of 8-nitro-1-fluoronaphthalene products are obtained after column chromatography. The method has the disadvantages of high production cost, low yield, difficult separation of mixed products and unsuitability for industrialized production.
In the acetic acid-nitric acid nitration method, 1-fluoronaphthalene is added into glacial acetic acid in the preparation process, 75% concentrated nitric acid is added, and the reaction is carried out for 2 hours at 70 ℃. After the reaction is finished, neutralizing the reaction solution with sodium hydroxide, extracting with ethyl acetate, washing with saturated saline solution, separating, drying with anhydrous sodium sulfate, performing suction filtration and concentration, and performing silica gel column chromatography on the obtained product to obtain a product, wherein the yield is about 72 percent, the reaction temperature is high, the explosion risk exists, the post-treatment operation is complex, and the method is not beneficial to industrial mass production.
In the sulfuric acid-nitric acid nitration method, a sulfuric acid-nitric acid mixed acid system is utilized to carry out nitration on fluoronaphthalene, and the mixed acid has the advantages of strong nitration capability, high reaction speed and high production capacity, so that the method is a main nitration process at present. Nitration reactions with mixed sulfuric-nitric acid systems are inherently hazardous, however, because they are generally highly exothermic and use strongly corrosive, toxic nitrating agents. It is therefore well known that nitration reactions are difficult to scale up and are one of the most dangerous reactions in chemical manufacture, and therefore conventional tank reactions present a significant safety risk.
Disclosure of Invention
The invention mainly aims to provide a method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction, and aims to solve the problem of high risk when a sulfuric acid-nitric acid mixed acid system is used for carrying out nitration on fluoronaphthalene.
In order to achieve the above object, the present invention provides a method for preparing 1-fluoro-4-nitronaphthalene by a microchannel reaction, the method comprising:
mixing 1-fluoronaphthalene with a first organic solvent to prepare a raw material solution;
mixing nitric acid and sulfuric acid to prepare a nitrifying liquid;
respectively pumping the raw material liquid and the nitrifying liquid into a microchannel reactor for reaction to obtain reaction liquid;
separating the reaction solution by a liquid separation tank to obtain a waste acid solution and an organic phase;
and adding the concentrated organic phase into a second organic solvent for recrystallization to obtain the target product.
Optionally, the first organic solvent is at least one of dichloromethane, dichloroethane, and chloroform.
Optionally, the mass concentration of the first organic solvent in the raw material liquid is 12% to 65%.
Optionally, the molar ratio of the nitric acid to the sulfuric acid is 1 to 1, the mass concentration of the sulfuric acid is 75 to 98%, and the mass concentration of the nitric acid is 60 to 98%.
Optionally, the dosage ratio of the raw material liquid and the nitrifying liquid is the molar ratio of the 1-fluoronaphthalene to the nitric acid, and is 1 to 1.
Optionally, the residence time of the raw material liquid and the nitrifying liquid in the microchannel reactor is 30-90 s, and the reaction temperature is 30-110 ℃.
Optionally, the organic phase is concentrated by evaporation or precipitation at a reduced temperature.
Optionally, the evaporation concentration treatment is performed under reduced pressure, and the evaporated solvent is recycled.
Optionally, the second organic solvent comprises methanol, ethanol, and propanol.
Optionally, the amount of the second organic solvent is 0.5 to 3 times of the mass of the concentrated organic phase.
According to the method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction, the pumping amount of the raw material liquid and the nitrifying liquid is controlled, so that the amount of materials for reaction in the microchannel reactor is small, the reaction temperature is controlled by utilizing the efficient heat transfer capacity of the microchannel reactor, the risk of explosion or thermal runaway is reduced, the safety of the preparation process is improved, the reaction in the microchannel reactor is continuously carried out, the operation controllability is stronger compared with the operation controllability in a batch processing environment, and the method has great advantages under the condition of large-scale industrial production.
Drawings
FIG. 1 is a schematic flow chart of an embodiment of the method for preparing 1-fluoro-4-nitronaphthalene by microchannel reaction according to the present invention;
FIG. 2 is a schematic view of a microchannel reactor used in the process for preparing 1-fluoro-4-nitronaphthalene according to the present invention;
FIG. 3 is a schematic structural diagram of a rhombic reaction channel used in the method for preparing 1-fluoro-4-nitronaphthalene by microchannel reaction according to the invention.
The implementation, functional features and advantages of the present invention will be further described with reference to the accompanying drawings.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with examples, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
It should be noted that if the description of "first", "second", etc. is provided in the embodiment of the present invention, the description of "first", "second", etc. is only for descriptive purposes and is not to be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, the expression "and/or" as used throughout is meant to encompass three juxtaposed aspects, exemplified by "A and/or B" and encompasses either A aspect, or B aspect, or both A and B aspects. Technical solutions between various embodiments may be combined with each other, but must be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
In the sulfuric acid-nitric acid nitration method, the nitration of fluoronaphthalene is performed using a sulfuric acid-nitric acid mixed acid system, but the nitration reactions under the sulfuric acid-nitric acid mixed acid system are inherently dangerous because they are generally highly exothermic and use a strongly corrosive, toxic nitrating agent, and therefore it is well known that the nitration reactions are difficult to scale up and are one of the most dangerous reactions in chemical manufacturing, and thus the conventional tank reaction has a great safety risk. In addition, the product 4-nitro-1-fluoronaphthalene of the reaction has strong volatility, can cause strong stimulation, causes stinging sensation and anaphylactic reaction due to skin stimulation, causes lacrimation due to severe stimulation to eyes, and therefore, the production process of the product is extremely unfriendly to operators and environment. In addition, in order to ensure stable product quality in the nitration of 1-fluoronaphthalene, precise control of the temperature and stoichiometry of the starting material should be ensured, since fluctuations in the reaction temperature and the amount of nitric acid lead to residual or excessive nitration of the starting material 1-fluoronaphthalene to give the dinitrate by-product 1-fluoro-2, 4-dinitronaphthalene.
The embodiment of the invention provides a method for preparing 1-fluoro-4-nitronaphthalene through a microchannel reaction, and referring to fig. 1, fig. 1 is a flow schematic diagram of an embodiment of the method for preparing 1-fluoro-4-nitronaphthalene through the microchannel reaction.
In this embodiment, the method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction includes:
step S10, mixing 1-fluoronaphthalene with a first organic solvent to prepare a raw material solution;
the synthetic route adopted in this example is:
the first organic solvent does not participate in the chemical reaction of the 1-fluoronaphthalene and the nitric acid, and can dissolve in the 1-fluoronaphthalene and the 1-fluoro-4-nitronaphthalene to prevent the 1-fluoro-4-nitronaphthalene from being separated out in a solid form to block the microchannel. Under stirring, 1-fluoronaphthalene is mixed with a first organic solvent to prepare a raw material solution. The first organic solvent is at least one of dichloromethane, dichloroethane and chloroform. The mass concentration of the first organic solvent in the raw material liquid is 12-65%. Preferably, the mass concentration of the first organic solvent in the raw material liquid is 40% to 60%.
Step S20, mixing nitric acid and sulfuric acid to prepare a nitrifying liquid;
in the reaction process, sulfuric acid can be used as a catalyst, so that the nitration reaction speed can be accelerated. Mixing nitric acid and sulfuric acid under stirring to prepare nitrifying liquid. The molar ratio of the nitric acid to the sulfuric acid is 1-1. Preferably, the mass concentration of the sulfuric acid is 80-98%.
S30, respectively pumping the raw material liquid and the nitrifying liquid into a microchannel reactor for reaction to obtain reaction liquid;
fig. 2 is a schematic combination diagram of a microchannel reactor, and as shown in fig. 2, a continuous flow reactor is a position where a raw material liquid and a nitrifying liquid react, a material preparation tank a is the raw material liquid, a material preparation tank B is the nitrifying liquid, the material preparation tank a and the material preparation tank B are respectively connected with a constant flow pump, the raw material liquid and the nitrifying liquid are respectively pumped into the continuous flow reactor through the constant flow pumps to react, and a reaction liquid generated after the reaction flows into a liquid separation tank.
FIG. 3 is a schematic diagram showing the structure of a reaction channel, and as shown in FIG. 3, the reaction channel in a continuous reactor may be composed of a plurality of connected rhomboid elementary channels. The rhombic element channel can reduce the flow resistance of liquid in the channel, so that the liquid can smoothly pass through the channel, the local accumulation of heat in the reaction process is prevented, and the heat dissipation is accelerated.
The dosage ratio of the raw material liquid and the nitrifying liquid is the molar ratio of the 1-fluoronaphthalene to the nitric acid, and is 1-1. Preferably, the molar ratio of 1-fluoronaphthalene to nitric acid is 1.1 to 1. The constant flow pump can control the flow rates of the raw material liquid and the nitrifying liquid, the flow rate of the raw material liquid is 0mL/min to 100mL/min, and the flow rate of the nitrifying liquid is 0mL/min to 100mL/min. The molar ratio of 1-fluoronaphthalene to nitric acid can be controlled by adjusting the flow rates of the raw material liquid and the nitrifying liquid respectively.
The residence time of the raw material liquid and the nitrifying liquid in the microchannel reactor for reaction is 30-90 s, and the reaction temperature is 30-110 ℃. Preferably, the residence time is 42s to 65s and the reaction temperature is 40 ℃ to 90 ℃. Residence time refers to the time of the feed liquid and the nitrified liquid in the continuous flow reactor.
Step S40, carrying out liquid separation on the reaction liquid through a liquid separation tank to obtain a waste acid liquid and an organic phase;
the reaction solution which is not separated may contain 1-fluoro-4-nitronaphthalene, 1-fluoronaphthalene, sulfuric acid, nitric acid, the first organic solvent, water, and a nitration by-product of 1-fluoronaphthalene. After the liquid separation, the waste acid liquid contains sulfuric acid and nitric acid, and the main component is sulfuric acid. The sulfuric acid in the waste acid solution can be recycled after concentration treatment. The organic phase mainly contains organic components such as 1-fluoro-4-nitronaphthalene and a first organic solvent.
The organic phase can be concentrated by evaporation or cooled for precipitation. When the evaporation concentration mode is used, the evaporation process is carried out under the reduced pressure condition, and the evaporated solvent can be recycled to obtain the oily concentrated solution. When the mode of temperature reduction precipitation is used, the precipitated solid is the object of subsequent recrystallization treatment.
And S50, adding the concentrated organic phase into a second organic solvent for recrystallization to obtain a target product.
The organic phase after concentration treatment is oily concentrated solution or solid obtained in the above steps. The second organic solvent used for recrystallization is an alcohol, and can be methanol, ethanol and propanol, and methanol is preferably used. The dosage of the second organic solvent is 0.5 to 3 times of the mass of the concentrated organic phase. Preferably, the amount of the second organic solvent used is 1.2 to 2 times the mass of the organic phase after the concentration treatment. In the recrystallization process, the target product 1-fluoro-4-nitronaphthalene is obtained after crystallization, centrifugation and drying.
The method for preparing 1-fluoro-4-nitronaphthalene through microchannel reaction provided by the embodiment adopts rhombic microchannel reaction equipment, can accurately add reaction raw materials by controlling the flow rate, ensure that a small amount of the reaction raw materials participate in the reactor, simultaneously control the reaction temperature by utilizing the efficient heat transfer capacity of the reactor, reduce the risk of explosion or thermal runaway, ensure safe reaction process and convenient post-treatment, and can obtain a product with the purity of up to 99% through further recrystallization.
Example 1
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of dichloroethane is 60%;
(2) The mass concentration of nitric acid in the raw material tank B is 65%, the mass concentration of sulfuric acid is 96%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.
(3) Respectively pumping the raw material solution and the nitrifying solution into a reactor through a constant flow pump, and controlling the dichloroethane solution of 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 30 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separation tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.3 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 81% and purity of 98%.
Example 2
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of the dichloroethane is 60%;
(2) The mass concentration of nitric acid in the raw material tank B is 65%, the mass concentration of sulfuric acid is 96%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.5.
(3) Respectively pumping the raw material liquid and the nitrifying liquid into a reactor by a constant flow pump, and controlling the dichloroethane solution of the 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 30 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separating tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.3 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 72% and purity of 97%.
Example 3
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of dichloroethane is 60%;
(2) The mass concentration of the nitric acid in the raw material tank B is 65%, the mass concentration of the sulfuric acid is 96%, and the molar ratio of the nitric acid to the sulfuric acid is 1.
(3) Respectively pumping the raw material solution and the nitrifying solution into a reactor through a constant flow pump, and controlling the dichloroethane solution of 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 40 ℃, reaction residence time 50s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separating tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 84% and purity of 99%.
Example 4
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of the dichloroethane is 40%;
(2) The mass concentration of nitric acid in the raw material tank B is 65%, the mass concentration of sulfuric acid is 96%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.
(3) Respectively pumping the raw material liquid and the nitrifying liquid into a reactor by a constant flow pump, and controlling the dichloroethane solution of the 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 40 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separation tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 72% and purity of 96%.
Example 5
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of the dichloroethane is 60%;
(2) The mass concentration of nitric acid in the raw material tank B is 65%, the mass concentration of sulfuric acid is 80%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.
(3) Respectively pumping the raw material liquid and the nitrifying liquid into a reactor by a constant flow pump, and controlling the dichloroethane solution of the 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 40 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separating tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 65% and purity of 95%.
Example 6
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of the dichloroethane is 60%;
(2) The mass concentration of nitric acid in the raw material tank B is 65%, the mass concentration of sulfuric acid is 96%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.
(3) Respectively pumping the raw material liquid and the nitrifying liquid into a reactor by a constant flow pump, and controlling the dichloroethane solution of the 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 40 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separation tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 85% and purity of 97%.
Example 7
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of the dichloroethane is 60%;
(2) The mass concentration of nitric acid in the raw material tank B is 80%, the mass concentration of sulfuric acid is 96%, and the molar ratio of mixed nitric acid and sulfuric acid is 1.
(3) Respectively pumping the raw material solution and the nitrifying solution into a reactor through a constant flow pump, and controlling the dichloroethane solution of 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2, reaction temperature 40 ℃, reaction residence time 60s.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separation tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling for crystallization, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 80% and purity of 96%.
Example 8
(1) Preparing dichloroethane solution of 1-fluoronaphthalene by using the raw material tank A, wherein the mass concentration of dichloroethane is 60%;
(2) The mass concentration of the nitric acid in the raw material tank B is 65%, the mass concentration of the sulfuric acid is 96%, and the molar ratio of the nitric acid to the sulfuric acid is 1.
(3) Respectively pumping the raw material liquid and the nitrifying liquid into a reactor by a constant flow pump, and controlling the dichloroethane solution of the 1-fluoronaphthalene: nitric acid: sulfuric acid molar ratio = 1.2.
(4) And after the reaction is finished, the reaction liquid is separated in a liquid separation tank, and the waste acid is recycled after being concentrated. The organic phase was evaporated and concentrated to recover the solvent to give an oily concentrate.
(5) Adding 1.5 times of methanol into the obtained concentrated solution, heating and dissolving under stirring, cooling and crystallizing, filtering, and drying to obtain 1-fluoro-4-nitronaphthalene with yield of 68% and purity of 98%.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of other like elements in a process, method, article, or system comprising the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
The above description is only a preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by using the contents of the present specification and the accompanying drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (10)
1. A method for preparing 1-fluoro-4-nitronaphthalene through a microchannel reaction is characterized by comprising the following steps:
mixing 1-fluoronaphthalene with a first organic solvent to prepare a raw material solution;
mixing nitric acid and sulfuric acid to prepare a nitrifying liquid;
respectively pumping the raw material liquid and the nitrifying liquid into a microchannel reactor for reaction to obtain reaction liquid;
separating the reaction solution by a liquid separation tank to obtain a waste acid solution and an organic phase;
and adding the concentrated organic phase into a second organic solvent for recrystallization to obtain the target product.
2. The microchannel reaction process of claim 1 to produce 1-fluoro-4-nitronaphthalene, wherein the first organic solvent is at least one of dichloromethane, dichloroethane, and chloroform.
3. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 1, wherein the mass concentration of the first organic solvent in the raw material liquid is 12% to 65%.
4. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 1, wherein the molar ratio of the nitric acid to the sulfuric acid is 1.
5. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 1, wherein the raw material liquid and the nitrifying liquid are used in a molar ratio of 1-fluoronaphthalene to nitric acid of 1.
6. The method for preparing 1-fluoro-4-nitronaphthalene by the microchannel reaction, according to claim 1, wherein the residence time of the raw material liquid and the nitration liquid in the microchannel reactor is 30s to 90s, and the reaction temperature is 30 ℃ to 110 ℃.
7. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 1, wherein the organic phase is concentrated by evaporation or temperature reduction.
8. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 7, wherein the evaporation and concentration treatment is performed under reduced pressure, and the evaporated solvent is recycled.
9. The microchannel reaction process of claim 1 to produce 1-fluoro-4-nitronaphthalene, wherein the second organic solvent comprises methanol, ethanol, and propanol.
10. The method for preparing 1-fluoro-4-nitronaphthalene according to claim 1, wherein the amount of the second organic solvent is 0.5 to 3 times the mass of the concentrated organic phase.
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