A method for preparing diether fluorene using microchannel reaction

Abstract

This invention discloses a method for preparing diether fluorene using microchannel reaction, comprising the following steps: (1) mixing 9-fluorenone, phenoxyethanol, and a co-catalyst at a certain temperature to form a uniform mobile phase 1, and using a strong acid catalyst as a mobile phase 2; (2) injecting mobile phase 1 and mobile phase 2 into a microchannel at a certain flow rate ratio and total volumetric flow rate to form a droplet flow for reaction, and diffusing the obtained product to a liquid-liquid separator, where the liquid and liquid phases are separated to obtain an ethyl acetate phase and an aqueous phase. The aqueous phase is used to recover the strong acid, and the ethyl acetate phase is concentrated and crystallized to obtain high-purity diether fluorene. This invention is the first to utilize microfluidic technology to prepare diether fluorene using 9-fluorenone and phenoxyethanol as the main reactants. The process is simple, energy-efficient, has a short reaction time, is green and safe, and is economical, making it suitable for large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology, specifically relating to a method for preparing diether fluorene using microchannel reaction. Background Technology

[0002] With the increasing demand for polymer optical resin materials such as polycarbonate, polyacrylate, and epoxy resin in my country, the market application prospects of bis(ether)fluorene (BPEF) are very promising. The research and development of synthesis technologies for bis(ether)fluorene and its downstream products is also a new topic in my country. Strengthening the research and development of bis(ether)fluorene synthesis technology is of great significance to my country's scientific and technological, high-tech fields, and social development and progress, in order to promote the development of functional polymer materials and optical film materials in China and drive technological development in related fields.

[0003] Currently, there are two main routes for the synthesis of diether fluorene:

[0004] Route 1: Using 9,9-bis(4-hydroxyphenyl)fluorene as a starting material, react with ethylene glycol carbonate, ethylene oxide, or 2-haloethanol to prepare diether fluorene. In this route, the expensive starting material 9,9-bis(4-hydroxyphenyl)fluorene significantly increases the synthesis cost of diether fluorene, making this route uncompetitive in the market.

[0005]

[0006] Route 2: Using 9-fluorenone as a raw material, reacting it with phenoxyethanol to prepare diether fluorene. This route has become the main research focus for the synthesis of diether fluorene due to its low overall cost. Specifically, there are reports [Green Chem. 2000, 2, 157-160; Bull. Chem. Soc. Jpn. 1933, 66, 2016-2032] on the synthesis of diether fluorene using supported heteropolyacids as catalysts. However, in this method, the catalyst preparation is too complex, the reaction temperature is too high (>170℃), the reaction yield is low, the recrystallization purification effect is not ideal, and the product purity is not good enough. Other reports [Japanese Patent 1994, 211729; CN 103058833 A; Japanese Patent Application Publication No. 7-165657; CN 101724159 B; Chem. Lett. 1998, 1055-1056] describe the use of concentrated sulfuric acid and a mercapto compound as catalyst and co-catalyst, respectively, to catalyze the synthesis of diether fluorene from 9-fluorenone and phenoxyethanol. In this method, concentrated sulfuric acid is inexpensive and readily available, and the yield of diether fluorene is high. However, to eliminate the influence of water, a byproduct generated during the reaction, a large excess of concentrated sulfuric acid (generally 2-5 times the molar amount of the starting material 9-fluorenone) is usually added. This allows the concentrated sulfuric acid to synergistically remove water, thereby promoting the smooth progress of the reaction. WO 2022 / 073343 A1 discloses a method for preparing diether fluorene from 9-fluorenone and phenoxyethanol using cyclohexane as a solvent and concentrated sulfuric acid and mercapto compounds as catalysts. This method utilizes the formation of an azeotrope between cyclohexane and water, thereby removing the byproduct water from the reaction system, promoting the reaction, and significantly reducing the amount of concentrated sulfuric acid catalyst required. However, this method introduces a large amount of additional organic solvent, and the reflux reaction time is long (24 hours), making it uneconomical and environmentally unfriendly.

[0007]

[0008] In summary, compared to Route 1, Route 2, with its cheaper and more readily available raw materials, has gained favor among researchers. However, Route 2 still faces certain challenges. For instance, it currently requires the addition of excessive amounts of phenoxyethanol (current technologies typically add more than 3.5 times the stoichiometric amount of 9-fluorenone), which increases the costs of raw materials and phenoxyethanol recovery. Furthermore, existing technologies all require the use of large quantities of strong acids, such as concentrated sulfuric acid, posing significant risks to large-scale production. Summary of the Invention

[0009] To address the aforementioned technical problems, the present invention aims to provide a method for preparing diether fluorene using microchannel reaction. This invention is the first to utilize microfluidic technology to prepare diether fluorene using 9-fluorenone and phenoxyethanol as the main reactants. The process is simple, energy-efficient, has a short reaction time, is green and safe, and is economical, making it suitable for large-scale production.

[0010] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0011] A method for preparing dietherfluorene using microchannel reaction includes the following steps:

[0012] (1) 9-fluorenone, phenoxyethanol and co-catalyst are stirred and mixed evenly at a certain temperature to form mobile phase 1, and strong acid catalyst is used as mobile phase 2.

[0013] (2) Mobile phase 1 and mobile phase 2 are injected into the microchannel at a certain flow rate ratio and total volume flow rate to form droplet flow for reaction. The resulting product diffuses into a liquid-liquid separator pre-filled with ethyl acetate and water. After liquid-liquid two-phase separation, ethyl acetate phase and water phase are obtained. The water phase is used to recover strong acid, and the ethyl acetate phase is concentrated and crystallized to obtain high-purity diether fluorene.

[0014] Preferably, the molar ratio of 9-fluorenone, phenoxyethanol, and co-catalyst is 1:2:(0.002-0.2).

[0015] Preferably, the co-catalyst is a thiol compound selected from at least one of 3-mercaptopropionic acid, thioglycolic acid, 3-mercaptopropanol, and 4-mercaptobutanol.

[0016] Preferably, in step (1), the mixing temperature of 9-fluorenone, phenoxyethanol and co-catalyst is 40-90°C.

[0017] In the above method, the strong acid catalyst can be an organic acid compound or an inorganic acid compound, preferably concentrated sulfuric acid or methanesulfonic acid.

[0018] In the above method, the flow rate ratio of mobile phase 1 to mobile phase 2 is 1:0.1 to 1:4, and the total volumetric flow rate is 2 to 30 ml / min; the total volumetric flow rate is controlled by an injection pump.

[0019] In the above method, the temperature of the microchannel reaction is consistent with the temperature at which 9-fluorenone, phenoxyethanol, and the co-catalyst are mixed.

[0020] Preferably, the diameter of the microchannel is 1 to 3 mm.

[0021] In the above method, the reaction pressure of the microchannel is 0.1–0.5 MPa, and the reaction time is 20–60 min.

[0022] In the above method, the microchannel is made of a hydrophobic material, such as polydimethylsiloxane (PDMS), polytetrafluoroethylene, polymethyl methacrylate (PMMA), stainless steel, etc., preferably polytetrafluoroethylene.

[0023] The beneficial effects of this invention are:

[0024] This invention uses microchannel reaction to prepare diether fluorene, which can effectively control the reaction of 9-fluorenone and phenoxyethanol at the theoretical stoichiometric ratio. At the same time, microchannel droplet reaction can effectively reduce the risks of large-scale use of strong acids. The reaction conditions are mild and the product yield is high.

[0025] Specifically, compared with the prior art, the present invention has the following advantages:

[0026] (1) This invention is the first to use microfluidic technology to prepare diether fluorene with 9-fluorenone and phenoxyethanol as the main reaction raw materials. The process is simple, energy consumption is low, reaction time is short, green and safe, economical and suitable for large-scale production.

[0027] (2) The present invention uses microchannel reaction to prepare diether fluorene, which effectively overcomes the problem of high raw material and phenoxyethanol recovery costs caused by the need to add excessive phenoxyethanol in the prior art, and makes the post-processing of diether fluorene simpler and more economical.

[0028] (3) The present invention uses microchannel reaction to prepare diether fluorene, which effectively overcomes the safety problem of large-scale use of strong acids such as concentrated sulfuric acid in the prior art;

[0029] (4) The present invention uses microchannel reaction to prepare diether fluorene. The system through microchannels and liquid-liquid separator can easily separate diether fluorene.

[0030] (5) The present invention uses microchannel reaction to prepare bis-ether fluorene, and the resulting product has high yield and high purity, and is suitable for further use in the preparation of epoxy resin, polycarbonate, polyaromatic ester, polyether and other polymer materials, and can be applied in aerospace, electronics, automobile manufacturing and other fields. Attached Figure Description

[0031] Figure 1 This is the reaction apparatus used in the method for preparing dietherfluorene using microchannel reaction of the present invention.

[0032] Figure 2 The liquid phase spectrum of the product diether fluorene obtained in Example 1 of this invention is shown. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0034] This invention provides a method for preparing diether fluorene using a microchannel reaction, and provides specific embodiments of the method. The synthesis of diether fluorene using 9-fluorenone and phenoxyethanol as raw materials is currently the main method on the market. However, existing technologies still require the addition of excess phenoxyethanol (generally more than 3.5 times the stoichiometry of 9-fluorenone). This excess phenoxyethanol necessitates additional recovery and purification processes, which increases the cost of raw materials and phenoxyethanol recovery to some extent. Furthermore, existing technologies all require the use of large amounts of strong acids such as concentrated sulfuric acid, which poses significant safety risks for large-scale production.

[0035] Based on the above problems, this invention innovatively uses microchannel reaction to prepare diether fluorene, which can effectively control the reaction of 9-fluorenone and phenoxyethanol in the theoretical stoichiometric ratio. At the same time, microchannel droplet reaction can effectively reduce the risks of large-scale use of strong acids, the reaction conditions are mild, and the yield of the product is high.

[0036] The method for preparing diether fluorene using microchannel reaction of the present invention employs the following... Figure 1 The apparatus shown performs the following steps:

[0037] (1) After stirring and mixing 9-fluorenone, phenoxyethanol and co-catalyst at a certain temperature, they are placed in the first container 1 at the same temperature as the mobile phase 1, and the strong acid catalyst is placed in the second container 2 as the mobile phase 2.

[0038] (2) Mobile phase 1 and mobile phase 2 are injected into microchannel 3 at a certain flow rate ratio and total volume flow rate to form droplet flow for reaction. The resulting product diffuses into liquid-liquid separator 4 which is pre-filled with ethyl acetate and water in a volume ratio of 1:1. After liquid-liquid two-phase separation, ethyl acetate phase and water phase are obtained. The water phase is used to recover strong acid, and the ethyl acetate phase is concentrated and crystallized to obtain high-purity diether fluorene.

[0039] In this invention, the theoretical stoichiometric ratio of 9-fluorenone to phenoxyethanol is 1:2. Based on this, a co-catalyst is added. The molar ratio of 9-fluorenone, phenoxyethanol, and co-catalyst is preferably 1:2:(0.002-0.2), more preferably 1:2:(0.008-0.1), and most preferably 1:2:(0.01-0.05).

[0040] In the above method, the co-catalyst is a thiol compound, preferably at least one of 3-mercaptopropionic acid, thioacetic acid, 3-mercaptopropanol, and 4-mercaptobutanol.

[0041] In step (1), the mixing temperature of 9-fluorenone, phenoxyethanol, and co-catalyst is 40-90°C, which is the same as the temperature of the first container.

[0042] In the above method, the strong acid catalyst can be an organic acid compound or an inorganic acid compound, preferably concentrated sulfuric acid or methanesulfonic acid.

[0043] In the above method, the flow rate ratio of mobile phase 1 to mobile phase 2 is 1:0.1 to 1:4, and the total volumetric flow rate is 2 to 30 ml / min; the total volumetric flow rate is controlled by an injection pump. More preferably, the flow rate ratio of mobile phase 1 to mobile phase 2 is 1:0.2 to 1:3, and the total volumetric flow rate is 4 to 25 ml / min; most preferably, the flow rate ratio of mobile phase 1 to mobile phase 2 is 1:0.5 to 1:2, and the total volumetric flow rate is 6 to 20 ml / min.

[0044] In the above method, the temperature of the microchannel reaction is consistent with the temperature at which 9-fluorenone, phenoxyethanol, and the co-catalyst are mixed.

[0045] In this invention, the diameter of the microchannel is 1-3 mm; in the above method, the reaction pressure of the microchannel is 0.1-0.5 MPa, and the reaction time is 20-60 min; the reaction temperature of the microchannel is consistent with the mixing temperature of 9-fluorenone, phenoxyethanol, and the co-catalyst, as well as the temperature of the first container.

[0046] In this invention, the microchannel is made of a hydrophobic material, such as polydimethylsiloxane (PDMS), polytetrafluoroethylene, polymethyl methacrylate (PMMA), stainless steel, etc., preferably polytetrafluoroethylene.

[0047] The diether fluorene prepared by this invention can be further used to prepare high molecular materials such as epoxy resin, polycarbonate, polyaromatic ester, and polyether, and applied in fields such as aerospace, electronics, and automobile manufacturing.

[0048] To further illustrate the present invention, the following describes in detail a method for preparing dietherfluorene using microchannel reaction, provided by the present invention, with reference to embodiments.

[0049] Example 1

[0050] 0.1 mol of 9-fluorenone, 0.2 mol of phenoxyethanol, and 0.001 mol of 3-mercaptopropionic acid co-catalyst were stirred evenly at 65°C and then placed in a first container at the same temperature as mobile phase 1. Concentrated sulfuric acid (98%) was placed in a second container as mobile phase 2. Mobile phases 1 and 2 were injected into a 2 mm diameter polytetrafluoroethylene microchannel using two separate syringe pumps at a flow rate ratio of 1:1. The reaction temperature was 65°C, the total flow rate was 12 ml / min, the reaction time was 40 min, and the reaction pressure was 0.3 MPa. The reaction system leaving the microchannel was separated into layers in a liquid-liquid separator pre-filled with ethyl acetate and water at a volume ratio of 1:1. The ethyl acetate layer was concentrated and crystallized to obtain the product dietherfluorene with a yield as high as 97% and a melting point of 119-120°C. Its liquid chromatography results are as follows: Figure 2 As shown, the liquid chromatography conditions were: mobile phase - methanol, column type - Shimadzu, Shim-pack VP-ODS250L*4.6P / N 228-34937-92; the liquid chromatogram data are shown in Table 1. From the liquid chromatogram, it can be concluded that the purity of the diether fluorene is as high as 99.91%.

[0051] Table 1

[0052] Peak Retention time area area% high high% 1 3.260 14159806 99.903 2073296 99.910 2 3.829 4624 0.033 514 0.025 3 4.001 9069 0.064 1352 0.065 total 14173498 100.000 2075162 100.000

[0053] Example 2

[0054] 0.1 mol of 9-fluorenone, 0.2 mol of phenoxyethanol, and 0.005 mol of 3-mercaptopropionic acid co-catalyst were stirred evenly at 40°C and then placed in a first container at the same temperature as mobile phase 1. Concentrated sulfuric acid (98%) was placed in a second container as mobile phase 2. Mobile phases 1 and 2 were injected into microchannels made of polytetrafluoroethylene with a diameter of 3 mm using two separate syringe pumps. The flow rate ratio of the two phases was 1:2. The reaction temperature was 40°C, the total volumetric flow rate was 6 ml / min, the reaction time was 60 min, and the reaction pressure was 0.1 MPa. The reaction system leaving the microchannels was separated into layers in a liquid-liquid separator pre-filled with ethyl acetate and water in a volume ratio of 1:1. The ethyl acetate layer was concentrated and crystallized to obtain the product dietherfluorene with a yield as high as 97.6% and a melting point of 119-120°C.

[0055] Example 3

[0056] 0.1 mol of 9-fluorenone, 0.2 mol of phenoxyethanol, and 0.003 mol of 3-mercaptopropionic acid co-catalyst were stirred evenly at 90°C and then placed in a first container at the same temperature as mobile phase 1. Concentrated sulfuric acid (98%) was placed in a second container as mobile phase 2. Mobile phases 1 and 2 were injected into microchannels made of polytetrafluoroethylene with a diameter of 2 mm using two separate syringe pumps. The flow rate ratio of the two phases was 1:0.5. The reaction temperature was 90°C, the total volumetric flow rate was 20 ml / min, the reaction time was 20 min, and the reaction pressure was 0.5 MPa. The reaction system leaving the microchannels was separated into layers in a liquid-liquid separator pre-filled with ethyl acetate and water at a volume ratio of 1:1. The ethyl acetate layer was concentrated and crystallized to obtain the product dietherfluorene with a yield as high as 96.9% and a melting point of 119-120°C.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0058] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for preparing bis-ether fluorene by microchannel reaction, characterized in that, The method comprises the following steps: (1) stirring 9-fluorenone, phenoxyethanol and a cocatalyst at a certain temperature to mix them uniformly as a mobile phase 1, and using a strong acid catalyst as a mobile phase 2; (2) injecting the mobile phase 1 and the mobile phase 2 into a microchannel at a certain flow rate ratio and total volume flow rate to form a droplet flow for reaction, and diffusing the obtained product to a liquid-liquid separator pre-added with ethyl acetate and water to separate the product into an ethyl acetate phase and a water phase, the water phase being used for recovering the strong acid, and the ethyl acetate phase being concentrated and crystallized to obtain high-purity bisphenol fluorene; The molar ratio of the 9-fluorenone, the phenoxyethanol and the cocatalyst is 1:2:(0.002-0.2). The flow rate ratio of the mobile phase 1 and the mobile phase 2 is 1:0.1-1:4, and the total volume flow rate is 2-30 ml / min.

2. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The cocatalyst is a mercapto compound selected from at least one of 3-mercaptopropionic acid, mercaptoacetic acid, 3-mercaptopropanol and 4-mercaptobutanol.

3. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, In step (1), the mixing temperature of the 9-fluorenone, the phenoxyethanol and the cocatalyst is 40-90℃.

4. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The strong acid catalyst is concentrated sulfuric acid or methyl sulfonic acid.

5. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The temperature of the microchannel reaction is consistent with the mixing temperature of the 9-fluorenone, the phenoxyethanol and the cocatalyst.

6. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The pipe diameter of the microchannel is 1-3 mm.

7. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The reaction pressure of the microchannel is 0.1-0.5 MPa, and the reaction time is 20-60 min.

8. The method for preparing bis-ether fluorene by micro-channel reaction according to claim 1, characterized in that, The material of the microchannel is polytetrafluoroethylene.

Images