Method for carrying out telomerization reaction by using microchannel

Abstract

The invention discloses a method for carrying out telomerization reaction by using a microchannel, which comprises the following specific steps: step 1, drying a solvent and a catalyst to ensure that the solvent and the catalyst do not contain water; 2, a reaction device is a micro-channel reactor, a solvent and a catalyst are uniformly stirred and then enter the micro-channel reactor through a peristaltic pump, acyl fluoride enters the micro-channel reactor through the peristaltic pump, and hexafluoropropylene oxide enters the micro-channel reactor in a gas form; 3, the microchannel reactor reacts at the temperature of-20 DEG C to 20 DEG C, and the length of a microchannel is 50 m; after the reaction, obtaining a layered solution, and taking lower-layer liquid as a target product.

Description

Technical Field

[0001] The present application relates to the technical field of organic synthesis, and in particular to a method for performing a telomerization reaction using a microchannel. Background Art

[0002] Perfluoroelastomer is composed of tetrafluoroethylene, perfluorinated methyl vinyl ether and a small amount of CF2=CF-OR f The ternary copolymer composed of X's curing point monomer (CSM) is the best variety of fluoroelastomers in terms of chemical resistance and temperature resistance. Among them, the fluoroelastomer containing cyanide curing points can form a triazine cross-linked network structure under the action of a catalyst, allowing the material to operate continuously at a temperature as high as 315°C with little performance loss and excellent compression permanent deformation performance. The synthesis route of the ternary copolymer is as follows:

[0003]

[0004] When n=2 in CN-CSM, the performance of the synthesized fluoroelastomer is the best. f -[(CF2-O-CF(CF3)] n In the polymerization synthesis of COF, the regulation of the degree of polymerization n is extremely critical, but the current existing technology is not ideal for the regulation of the degree of polymerization n. In the existing technology, the synthesis route of CN-CSM is as follows:

[0005]

[0006] Wherein, X=COOR, CN. Summary of the invention

[0007] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a method for performing polymerization reaction using a microchannel to solve the problems in the prior art of low yield of the product with n=2 and unsatisfactory control effect on n in the preparation of CN-CSM.

[0008] In order to solve the above technical problems, this application adopts the following technical solutions:

[0009] A method for telomerization reaction using a microchannel, the specific steps are as follows:

[0010] Step 1: Dry the solvent and catalyst to ensure that there is no moisture in the solvent and catalyst;

[0011] Step 2: The reaction device is a microchannel reactor, the solvent and the catalyst are stirred evenly and then enter the microchannel reactor through a peristaltic pump, the acyl fluoride enters the microchannel reactor through the peristaltic pump, and the hexafluoropropylene oxide enters the microchannel reactor in the form of gas; wherein the catalyst is tetramethylethylenediamine or triethylamine, and the solvent is one of tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, and acetonitrile; the molar ratio of acyl fluoride to catalyst is 1:(0.02-0.1), and the volume ratio of solvent to catalyst is (15-25):1; the gas flow rate of hexafluoropropylene oxide is 5-15 mL / min;

[0012] Step 3: The microchannel reactor is reacted at -20°C to 20°C, and the length of the microchannel is 50 meters; after the reaction, a layered solution is obtained, and the lower layer liquid is the target product.

[0013] Preferably, in step 1, the solvent is dried with calcium hydride for 10 hours, then redistilled and 4A molecular sieve is added thereto for standby use; the 4A molecular sieve is dried at 800° C. for 6 hours, and 100 g of 4A molecular sieve is added to every 500 mL of solvent or catalyst.

[0014] Preferably, in step 2, the structural formula of the acyl fluoride is as follows:

[0015] X is -OMe or -CN.

[0016] Preferably, according to the ratio of gas chromatographic peak area, in the target product, the product with a polymerization degree of 2 accounts for at least 20% of the target product.

[0017] Preferably, in step 2, a cross-shaped mixer is provided at the feed inlet of the microchannel reactor, and the mixer has a first feed inlet, a second feed inlet, a third feed inlet and a discharge port; the discharge port is fluidly connected to the feed inlet of the microchannel reactor; the solvent and the catalyst are mixed and fluidly enter from the first feed inlet, the acyl fluoride enters from the second feed inlet, and the hexafluoropropylene oxide enters from the third feed inlet; the solvent, the catalyst, the acyl fluoride and the hexafluoropropylene oxide are mixed in the mixer and then enter the microchannel reactor.

[0018] Compared with the prior art, this application has the following beneficial effects:

[0019] 1. The present application has conducted an in-depth study on the prior art and applied a microchannel reactor to the telomerization reaction of acyl fluoride and hexafluoropropylene oxide. The extremely high heat and mass transfer efficiency of the microchannel reactor is utilized to enable the reaction conditions to be accurately controlled within a very narrow temperature range. At the same time, the gaseous sulfuric acid of hexafluoropropylene oxide can be adjusted as needed, thereby achieving a high degree of controllability of the reaction conditions, helping to reduce the occurrence of side reactions and improving the selectivity and yield of the target product.

[0020] 2. After the microchannel reactor is adopted in the present application, the product system is mainly concentrated in the range of n=0 to 3, especially the product with n=2 accounts for a significantly increased proportion. Compared with the products prepared by the traditional kettle reactor, the product with n=2 accounts for less than 20%. The method described in the present application not only increases the proportion of the target product, but also effectively reduces the generation of oligomers and other by-products.

[0021] 3. The method described in the present application is easier to operate, reduces the influence of human factors on the experimental results, and the whole process has a high degree of automation and is easy to monitor and adjust. At the same time, the miniaturization of the microchannel reactor enables it to simulate industrial production conditions on a laboratory scale, greatly simplifies the transition process from laboratory to industrial production, reduces the difficulty of scale-up production, and has a good prospect for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a flow chart of a method for performing telomerization reaction using a microchannel. DETAILED DESCRIPTION

[0023] This application will combine the embodiments of this application and the accompanying drawings to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on this application belong to the scope of protection of this application.

[0024] Unless otherwise indicated in specific cases in this application, the numerical ranges listed herein include the upper and lower limits, as well as all integers and fractions within the range, and are not limited to the specific values ​​listed when defining the range.

[0025] 1. A method for telomerization reaction using microchannels

[0026] Step 1: Dry the solvent and catalyst to ensure that there is no moisture in the solvent and catalyst;

[0027] Step 2: The reaction device is a microchannel reactor, the solvent and the catalyst are stirred evenly and then enter the microchannel reactor through a peristaltic pump, the acyl fluoride enters the microchannel reactor through the peristaltic pump, and the hexafluoropropylene oxide enters the microchannel reactor in the form of gas; wherein the catalyst is tetramethylethylenediamine or triethylamine, and the solvent is one of tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, and acetonitrile; the molar ratio of acyl fluoride to catalyst is 1:(0.02-0.1), and the volume ratio of solvent to catalyst is (15-25):1; the gas flow rate of hexafluoropropylene oxide is 5-15 mL / min;

[0028] Step 3: The microchannel reactor is reacted at -20°C to 20°C, and the length of the microchannel is 50 meters; after the reaction, a layered solution is obtained, and the lower layer liquid is the target product.

[0029] When studying the prior art, the present application found that, with reference to US4345092A and US4138426A, inorganic salts were used as catalysts in a kettle reactor to screen the conditions for the telomerization reaction, but the screening results showed that no matter what the reaction conditions were, the products of n=1 to 8 were present in the obtained product system, and the mass proportion of the products of n=2 in the product system was less than 20%. For this reason, the present application considers replacing the catalyst and using tertiary amine as a catalyst. However, when the present application uses tertiary amine as a catalyst to feed the reactor, it is found that the solvent, acyl fluoride, and catalyst are first put into the kettle, and when the gas is finally introduced, a large amount of acyl fluoride and tertiary amine will release heat violently, which will cause the safety of the entire reaction process to be affected, so if tertiary amine is used as a catalyst, it is not suitable to react in the reactor. Finally, the present application considers replacing the reactor to conduct experiments, and uses a microchannel reactor for the telomerization reaction of acyl fluoride and hexafluoropropylene oxide. The present application also unexpectedly discovered that if an inorganic salt is used as a catalyst, clogging is very likely to occur in the microchannel. At this time, the use of a tertiary amine as a catalyst can not only solve the problem of microchannel clogging, but also the solvent, acyl fluoride, catalyst, and gas in the microchannel reactor react slowly and in small amounts. The microchannel reactor has extremely high heat and mass transfer efficiency, which can completely avoid the occurrence of violent heat release.

[0030] In some embodiments of the present application, in step 2, the molar ratio of acyl fluoride to catalyst is 1: (0.02-0.1), more preferably 1: 0.05, the amount of catalyst is controlled, and this low amount of catalyst can ensure the smooth progress of the reaction without introducing too many impurities, reducing the generation of by-products. Therefore, the molar ratio of acyl fluoride to catalyst can be 1: 0.02, 1: 0.05, 1: 0.08, 1: 0.1, etc., and all ranges and sub-ranges between the above values; the volume ratio of solvent to catalyst is (15-25): 1, preferably 20: 1, therefore, the volume ratio of solvent to catalyst can be 15: 1, 20: 1, 25: 1, etc., and all ranges and sub-ranges between the above values; it should be understood that in the embodiment, any of the above ranges can be combined with any other ranges.

[0031] In some embodiments of the present application, in step 3, the microchannel reactor is reacted at -20°C to 20°C, and the temperature can be -20°C, -15°C, -10°C, 0°C, 10°C, 20°C, etc., and all ranges and sub-ranges between the above values. It should be understood that in the embodiments, any of the above ranges can be combined with any other ranges.

[0032] In some embodiments of the present application, in step 1, the solvent is dried with calcium hydride for 10 hours, then redistilled and 4A molecular sieve is added thereto for standby use; the 4A molecular sieve is dried at 800°C for 6 hours, and 100g of 4A molecular sieve is added to every 500mL of solvent or catalyst. Since both the raw materials and the reaction products are acyl fluoride compounds, they are easily converted into carboxylic acids when exposed to water, so the water content in the reaction system needs to be strictly controlled to ensure that no water enters the reaction system.

[0033] In some embodiments of the present application, in step 2, the structural formula of the acyl fluoride is as follows:

[0034] X is -OMe or -CN.

[0035] In some embodiments of the present application, according to the gas chromatographic peak area ratio, in the target product, the product with a polymerization degree of 2 accounts for at least 20% of the target product.

[0036] In some embodiments of the present application, in step 2, a cross-type mixer is provided at the feed port of the microchannel reactor, and the mixer has a first feed port, a second feed port, a third feed port and a discharge port; the discharge port is connected to the fluid of the feed port of the microchannel reactor; the solvent and the catalyst are mixed and fluid enter from the first feed port, the acyl fluoride enters from the second feed port, and the hexafluoropropylene oxide enters from the third feed port, and a gas mass flowmeter is also provided at the third feed port for detecting the flow rate of hexafluoropropylene oxide; the solvent, the catalyst, the acyl fluoride and the hexafluoropropylene oxide are mixed in the mixer and enter the microchannel reactor. The solvent, the catalyst, the acyl fluoride and the hexafluoropropylene oxide are pre-mixed by the cross-type mixer before entering the microchannel reactor, so that the acyl fluoride and the catalyst are slowly contacted to avoid violent heat release and ensure the safe conduct of the reaction.

[0037] 2. Embodiment

[0038] Example 1

[0039] Step 1: The solvent was dried with calcium hydride for 24 hours, redistilled and stored with 4A molecular sieves for later use. The 4A molecular sieves were dried at 800°C for 6 hours, and 100 g of 4A molecular sieves were added to every 500 mL of solvent or catalyst for later use.

[0040] Step 2: Microchannel reactor feeding:

[0041] First feed port: Dissolve 1 mmol of catalyst in 20 mL of solvent, stir evenly, and feed through a peristaltic pump.

[0042] The second feed port: 20 mmol acyl fluoride, fed by a peristaltic pump; an acyl fluoride compound in which X is -OMe was used.

[0043] The third feed inlet: hexafluoropropylene oxide gas is fed through a gas mass flow meter.

[0044] The liquid and gas enter the microchannel reactor after passing through a cross-shaped mixer and react at a low temperature of -10°C. After the reaction, a layered solution is obtained, and the lower layer of liquid is the target product.

[0045] According to the steps of Example 1, when the reaction solvent is diethylene glycol dimethyl ether and the catalyst is tetramethylethylenediamine, the proportions of each compound in the target product system are as follows:

[0046] Table 1

[0047]

[0048] According to the steps of Example 1, when the reaction solvent is tetraethylene glycol dimethyl ether and the catalyst is tetramethylethylenediamine, the proportions of each compound in the target product system are as follows:

[0049] Table 2

[0050]

[0051] According to the steps of Example 1, when the reaction solvent is tetraethylene glycol dimethyl ether and the catalyst is triethylamine, the proportions of each compound in the target product system are as follows:

[0052] Table 3

[0053]

[0054] Comparative Example

[0055] The above reaction was carried out in a reactor, and a three-necked flask was used as the reactor. The catalyst was placed in the three-necked flask. The three ports were connected to a vacuum pump, a pressure gauge, and a thermometer, respectively, and solvents, catalysts, and acyl fluorides were added in sequence. Vacuum was evacuated and hexafluoropropylene oxide (HFPO) was replaced three times. Stirring was turned on, and HFPO was introduced under negative pressure. The vacuum degree of the system and the absorption amount of HFPO were adjusted by a vacuum regulator. After the reaction was completed, the reaction mixture was transferred to a separatory funnel to separate the solvent layer and the fluorocarbon layer, and the fluorocarbon layer product was subjected to gas phase detection. With CsF as the main catalyst, the reaction conditions of acyl fluoride and HFPO were screened, including the amount of catalyst, the absorption amount of HFPO, the reaction solvent, the reaction temperature, etc., as shown in Table 4:

[0056] Table 4

[0057] Comparative Example CsF dosage HFPO absorption Reaction solvent Reaction temperature 1 0.05 2.0equiv. Tetraglyme -10℃ 2 0.1 2.0equiv. Tetraglyme -10℃ 3 0.2 2.0equiv. Tetraglyme -10℃ 4 0.2 1.2equiv. Tetraglyme -10℃ 5 0.2 1.5equiv. Tetraglyme -10℃ 6 0.2 1.8equiv. Tetraglyme -10℃ 7 0.2 1.5equiv. diglyme -10℃ 8 0.2 1.5equiv. <![CDATA[CH3CN]]> -10℃ 9 0.2 1.5equiv. THF -10℃ 10 0.2 1.5equiv. Tetraglyme 0℃ 11 0.2 1.5equiv. Tetraglyme 10℃ 12 0.2 1.5equiv. Tetraglyme 25℃

[0058] See Table 5 for specific results.

[0059] Table 5

[0060]

[0061] Comparing the embodiments with the comparative examples, it can be seen that:

[0062] (1) Since the comparative example uses a traditional reactor, even if the reaction temperature and the amount of catalyst are optimized, the effect is not ideal, and the selectivity and yield of the product are still low, especially the proportion of products with n=4 and higher polymerization degree is always high, and the overpolymerization phenomenon is more serious; while the embodiment well suppresses the occurrence of overpolymerization phenomenon. In the products prepared in the embodiment, the n value is maintained between 1 and 3, and no products with other n values ​​appear. This shows that in the products prepared in the embodiment, the n value distribution is narrower than that in the comparative example, and also shows that the method described in the present application can improve the selectivity of the reaction and reduce the generation of products with other polymerization degrees.

[0063] (2) Although the proportion of the product with n=2 in some comparative examples is more than 20%, such as comparative examples 5 and 10-12, the products prepared in these comparative examples still contain a considerable amount of products with a polymerization degree of n=4 or above; while in the examples, no products with a polymerization degree of n=4 or above are generated at all. It can be seen that the use of a microchannel reactor can well control the polymerization reaction, so that the content of the product with n=2 in the final product is significantly increased, and can even reach more than 50%.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application rather than to limit the technical solution. Ordinary technicians in this field should understand that those modifications or equivalent substitutions of the technical solution of the present application that do not depart from the purpose and scope of the technical solution of the present application should be included in the scope of the claims of the present application.

Claims

1. A method for telomerization reaction using a microchannel, characterized in that: The specific steps are as follows: Step 1: Dry the solvent and catalyst to ensure that there is no moisture in the solvent and catalyst; Step 2: The reaction device is a microchannel reactor, the solvent and the catalyst are stirred evenly and then enter the microchannel reactor through a peristaltic pump, the acyl fluoride enters the microchannel reactor through the peristaltic pump, and the hexafluoropropylene oxide enters the microchannel reactor in the form of gas; wherein the catalyst is tetramethylethylenediamine or triethylamine, and the solvent is one of tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran, and acetonitrile; the molar ratio of acyl fluoride to catalyst is 1:(0.02-0.1), and the volume ratio of solvent to catalyst is (15-25):1; the gas flow rate of hexafluoropropylene oxide is 5-15 mL / min; Step 3: The microchannel reactor is reacted at -20°C to 20°C, and the length of the microchannel is 50 meters; after the reaction, a layered solution is obtained, and the lower layer liquid is the target product.

2. The method according to claim 1, characterized in that: In step 1, the solvent is dried with calcium hydride for 10 hours, then redistilled and 4A molecular sieve is added thereto for standby use; the 4A molecular sieve is dried at 800° C. for 6 hours, and 100 g of 4A molecular sieve is added to every 500 mL of solvent or catalyst.

3. The method according to claim 1, characterized in that: In step 2, the structural formula of the acyl fluoride is as follows: X is -OMe or -CN.

4. The method according to claim 2, characterized in that: According to the ratio of gas chromatography peak area, among the target products, the product with a polymerization degree of 2 accounts for at least 20% of the target products.

5. The method according to claim 1, characterized in that: In step 2, a cross-shaped mixer is provided at the feed inlet of the microchannel reactor, and the mixer has a first feed inlet, a second feed inlet, a third feed inlet and a discharge port; the discharge port is fluidly connected to the feed inlet of the microchannel reactor; the solvent and the catalyst are mixed and fluidly enter from the first feed inlet, the acyl fluoride enters from the second feed inlet, and the hexafluoropropylene oxide enters from the third feed inlet; the solvent, the catalyst, the acyl fluoride and the hexafluoropropylene oxide are mixed in the mixer and then enter the microchannel reactor.

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