A process for the preparation of a fluorine-containing diene compound

Abstract

The present application provides a preparation method of fluorine-containing diene compound, which comprises the step of adding I(CF2CF2) n I with ethylene to obtain ICH2CH2(CF2CF2) n CH2CH2I, wherein a catalyst CuI is added in the addition reaction; the fluorine-containing diene compound has a general chemical formula of CH2=CH(CF2CF2) n CH=CH2, and n=1, 2, 3. By adding the catalyst CuI in the addition reaction, the present application increases the selectivity of the main product ICH2CH2(CF2CF2) n CH2CH2I to more than 98%, and reduces the by-product ICH2CH2(CF2CF2) n I, greatly improves the generation of ICH2CH2(CF2CF2) n CH2CH2I, and further guarantees the subsequent preparation of the fluorine-containing diene compound with high purity.

Description

Technical Field

[0001] This invention relates to the field of fluorine compound preparation, and more particularly to a method for preparing a fluorine diene compound. Background Technology

[0002] Fluorinated dienes have the following general formula: CH2=CH(CF2CF2) n CH=CH2, where n=1,2,3. Fluorinated dienes are not only used in the production of fluorinated elastomers, but also as monomer precursors for block copolymers, silicon-containing polymers, or films, making them important chemical intermediates.

[0003] Currently, the preparation method for this fluorinated diene compound is as follows: using elemental iodine and tetrafluoroethylene as raw materials, a diiodoperfluoroalkane compound I (CF2CF2) is obtained through an iodination reaction. n I, then diiodoperfluoroalkane I (CF2CF2) n The addition of ethylene (I) yields the product with the general formula ICH2CH2(CF2CF2). n The compound CH2CH2I, in the presence of a solvent, at a certain temperature and under the action of a strong base, undergoes dehydrogenation to produce a fluorinated diene compound.

[0004] However, I(CF2CF2) n The addition reaction of ethylene with iodine usually yields ICH2CH2(CF2CF2). n CH2CH2I and ICH2CH2(CF2CF2) n A mixture of I requires ICH2CH2(CF2CF2) to be added. n CH2CH2I is first separated from the reaction system through extraction and recrystallization, and then subjected to the de-HI reaction. The process is complex and the overall yield is not high. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing fluorinated diene compounds, which can obtain the target fluorinated diene compounds simply and efficiently.

[0006] This invention provides a method for preparing a fluorinated diene compound, comprising: I(CF2CF2) n I reacts with ethylene in an addition reaction to give ICH2CH2(CF2CF2). n In the CH2CH2I step, the catalyst CuI is added to the addition reaction;

[0007] The general chemical formula of the fluorinated diene compound is CH2=CH(CF2CF2). n CH=CH2, n=1,2,3.

[0008] This invention achieves the main product ICH2CH2(CF2CF2) by adding the catalyst CuI to the addition reaction. n The selectivity of CH2CH2I is increased to over 98%, reducing the byproduct ICH2CH2(CF2CF2). n The generation of I greatly increases the yield of ICH2CH2(CF2CF2). n The purity of CH2CH2I is crucial for the subsequent preparation of high-purity fluorinated diene compounds CH2=CH(CF2CF2). n CH=CH2, n=1,2,3 provides a guarantee.

[0009] Furthermore, after the addition reaction is completed, no post-processing is performed; instead, the de-HI reaction is carried out directly while the fluorinated diene compound of the product is distilled.

[0010] In existing technologies, after the addition reaction is complete, it is necessary to remove ICH2CH2(CF2CF2). n CH2CH2I is first separated from the reaction system through extraction and recrystallization, and then subjected to a de-HI reaction. However, in this invention, no post-processing is performed after the addition reaction. The de-HI reaction is carried out directly while the fluorinated diene compound is distilled. This can effectively reduce the production process and the purity of the obtained product is also high. That is, the target fluorinated diene compound can be prepared simply and in high yield, which is suitable for large-scale production.

[0011] To achieve the simplified reaction process described above, the addition reaction is carried out in a distillation vessel.

[0012] Furthermore, the distillation vessel is made of Hastelloy C276.

[0013] Furthermore, the addition reaction is carried out at a temperature of 180–220°C for 5–8 hours, involving the reaction of ethylene with I(CF2CF2). n The molar ratio of I is 3 to 5:1.

[0014] In a preferred embodiment of the present invention, the reaction temperature of the addition reaction is 200°C.

[0015] In a specific embodiment of the present invention, the preparation method includes the following steps:

[0016] (1) Using tetrafluoroethylene as a raw material, it reacts with iodine to obtain the general formula I(CF2CF2). n Compounds of I, where n = 1, 2, 3;

[0017] (2) Add the catalyst CuI to the distillation vessel and dissolve I(CF2CF2). nI reacts with ethylene in an addition reaction to give the product with the general formula ICH2CH2(CF2CF2). n Compounds of CH2CH2I, where n = 1, 2, 3;

[0018] (3) Add solvent and strong base to the distillation vessel to carry out the de-HI reaction and simultaneously distill the fluorinated diene compound of the product.

[0019] In step (1), the reaction temperature of tetrafluoroethylene with iodine is 150-180℃, the reaction time is 1-3h, and the molar ratio is 1.2-3.5:1.

[0020] In step (3), the solvent is one or more of ethanol, ethylene glycol, and isopropanol.

[0021] In step (3), the strong base is NaOH, KOH or triethylamine.

[0022] In step (3), the reaction temperature is 80–120°C, and the strong base reacts with ICH2CH2(CF2CF2). n The molar ratio of CH2CH2I is 1.2 to 1.5:1.

[0023] This invention provides a method for preparing a fluorinated diene compound by adding a catalyst CuI to the addition reaction, thereby producing the main product ICH2CH2(CF2CF2). n The selectivity of CH2CH2I is increased to over 98%, reducing the byproduct ICH2CH2(CF2CF2). n The generation of I greatly increases the yield of ICH2CH2(CF2CF2). n The purity of CH2CH2I is crucial for the subsequent preparation of high-purity fluorinated diene compounds CH2=CH(CF2CF2). n CH=CH2, n=1,2,3 provides a guarantee. Attached Figure Description

[0024] Figure 1 The GCMS spectrum of CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2 obtained in Example 3;

[0025] Figure 2 The 1H NMR spectrum of CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2 obtained in Example 3;

[0026] Figure 3 The 13C NMR spectrum of CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2 obtained in Example 3;

[0027] Figure 4The image shows the 19F NMR spectrum of CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2 obtained in Example 3. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0029] For any experimental steps or conditions not specified in the following examples, the procedures or conditions should be performed according to the conventional experimental procedures described in the literature in this field. Reagents and instruments whose manufacturers are not specified can be obtained commercially.

[0030] The tetrafluoroethylene used in the examples was manufactured by Zhonghao Chenguang Chemical Research Institute Co., Ltd.

[0031] Elemental iodine was purchased from Qingdao Tuohai Iodine Products Co., Ltd.

[0032] The ethylene was purchased from Chengdu Jinhong Chemical Co., Ltd.

[0033] CuI, KOH, ethanol, and isopropanol were purchased from Chengdu Kelong Chemical Co., Ltd.

[0034] Example 1

[0035] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CH=CH2, the specific steps of which are as follows:

[0036] 3500g (13.8mol) of I2 was added to a 5L Hastelloy C276 reactor. After purging and replacing with high-purity N2 three times, 1656g (16.6mol) of TFE (tetrafluoroethylene) was added. The reactor was heated to 150°C with stirring and the reaction was stopped after 2 hours. The reactor was then cooled to room temperature and the unreacted TFE was discharged.

[0037] 18g (0.09mol) of CuI was added, and after purging and replacing it three times with high-purity N2, 1160g (41.4mol) of ethylene was added, and the temperature was raised to 200℃ and reacted for 5h.

[0038] After the reaction was completed, 927 g (16.6 mol) of solid KOH and 8000 g of isopropanol solution were added to the reactor. The mixture was refluxed at 80 °C for 20 min with stirring. The product was collected at a reflux ratio of 4:2.

[0039] The final product collected was 1910g, with a yield of 90%, and the purity was 98% as determined by GC-MS. 19 F-NMR confirmed the structure as CH2=CHCF2CF2CH=CH2.

[0040] Example 2

[0041] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CF2CF2CH=CH2, and the specific steps are as follows:

[0042] 3500g (13.8mol) of I2 was added to a 5L Hastelloy C276 reactor. After purging and replacing with high-purity N2 three times, 3174g (31.7mol) of TFE was added. The reactor was heated to 150℃ with stirring and the reaction was stopped after 2 hours. The reactor was then cooled to room temperature and the unreacted TFE was discharged.

[0043] Add 18g (0.09mol) CuI, purge and replace with high-purity N2 three times, then add 1160g (41.4mol) ethylene, and heat to 200℃ to react for 5h.

[0044] After the reaction was completed, 927 g (16.6 mol) of solid KOH and 8000 g of ethylene glycol solution were added to the reactor. The mixture was refluxed at 90 °C for 20 min with stirring. The product was collected at a reflux ratio of 4:2.

[0045] The final product collected was 2800g, with a yield of 80%, and the purity was 96.5% as determined by GC-MS. 19 F-NMR determined the structure to be CH2=CHCF2CF2CF2CF2CH=CH2.

[0046] Example 3

[0047] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2, and the specific steps are as follows:

[0048] 3500g (13.8mol) of I2 was added to a 5L Hastelloy C276 reactor. After purging and replacing with high-purity N2 three times, 4830g (48.3mol) of TFE was added. The reactor was heated to 150℃ with stirring and the reaction was stopped after 2 hours. The reactor was then cooled to room temperature and the unreacted TFE was discharged.

[0049] Add 18g (0.09mol) CuI, purge and replace with high-purity N2 three times, then add 1160g (41.4mol) ethylene, and heat to 200℃ to react for 5h.

[0050] After the reaction was completed, 927 g (16.6 mol) of solid KOH and 8000 g of ethylene glycol solution were added to the reactor. The mixture was refluxed at 120 °C for 20 min with stirring. The product was collected at a reflux ratio of 4:2.

[0051] The final product collected was 4495g, with a yield of 92%, and the purity was 98% as determined by GC-MS. 19 F-NMR determined the structure to be CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2.

[0052] Figure 1 This is the GCMS spectrum of the product obtained in this embodiment. Figure 2 The image shows the 1H NMR spectrum of the product obtained in this embodiment. Figure 3 This is the 13C NMR spectrum. Figure 4 This is the 19F NMR spectrum.

[0053] Example 4

[0054] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CF2CF2CH=CH2, and the specific steps are as follows:

[0055] 3500g (13.8mol) of I2 was added to a 5L Hastelloy C276 reactor. After purging and replacing with high-purity N2 three times, 3174g (31.7mol) of TFE was added. The reactor was heated to 150℃ with stirring and the reaction was stopped after 2 hours. The reactor was then cooled to room temperature and the unreacted TFE was discharged.

[0056] Add 18g (0.09mol) CuI, purge and replace with high-purity N2 three times, then add 1932g (69mol) ethylene, and heat to 200℃ to react for 6h;

[0057] After the reaction was completed, 927 g (16.6 mol) of solid KOH and 8000 g of ethanol solution were added to the reaction vessel. The mixture was refluxed at 90 °C for 20 min with stirring. The product was collected at a reflux ratio of 4:2.

[0058] The final product collected was 3360g, with a yield of 96%, and the purity was 96.5% as determined by GC-MS. 19 F-NMR determined the structure to be CH2=CHCF2CF2CF2CF2CH=CH2.

[0059] Example 5

[0060] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CH=CH2, the specific steps of which are as follows:

[0061] 3500 g (13.8 mol) of I₂ was added to a 5 L Hastelloy C276 reactor. After purging and replacing with high-purity N₂ three times, 1656 g (16.6 mol) of TFE was added. The reactor was heated to 150 °C with stirring and reacted for 2 h. The reaction was then stopped, and the reactor was cooled to room temperature to remove unreacted TFE. After purging and replacing with high-purity N₂ three times, 1160 g (41.4 mol) of ethylene was added, and the reactor was heated to 200 °C and reacted for 5 h. After the reaction was completed, 927 g (16.6 mol) of solid KOH and 8000 g of isopropanol solution were added to the reactor. The reactor was refluxed at 80 °C with stirring for 20 min. The product was collected at a reflux ratio of 4:2, and a final product of 1270 g was collected, with a yield of 60%. The purity was 98% as determined by GC-MS. 19 F-NMR confirmed the structure as CH2=CHCF2CF2CH=CH2.

[0062] Example 6

[0063] This embodiment provides a method for preparing the fluorinated diene compound CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2, and the specific steps are as follows:

[0064] 3500g (13.8mol) of I2 was added to a 5L Hastelloy C276 reactor. After purging and replacing with high-purity N2 three times, 4830g (48.3mol) of TFE was added. The reactor was heated to 150℃ with stirring and the reaction was stopped after 2 hours. The reactor was then cooled to room temperature and the unreacted TFE was discharged.

[0065] After purging and replacing with high-purity N2 three times, 1160g (41.4mol) of ethylene was added, and the temperature was raised to 200℃ and reacted for 5h.

[0066] After the reaction was completed, 2000 mL of acetonitrile was added to the reaction vessel, and stirring was started. After stirring for 20 min, the mixed solvent was released, and the mixture was extracted with n-hexane by heating. The upper oil phase was then taken and the solvent was distilled off to obtain 5471 g of white crystalline solid.

[0067] 5471g of the obtained white crystals were added to a reaction vessel, along with 927g (16.6mol) of solid KOH and 8000g of ethylene glycol solution. The reaction was carried out at 120℃ with stirring for 3 hours. After the reaction was completed, 3240g of the product was collected by distillation from the solvent, with a yield of 65%. GC-MS analysis showed that the purity was 98%. 19 F-NMR determined the structure to be CH2=CHCF2CF2CF2CF2CF2CF2CH=CH2.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a fluorinated diene compound, comprising the following steps: (1) Add the catalyst CuI to the distillation vessel and mix I(CF2CF2) n I reacts with ethylene in an addition reaction to give the product with the general formula ICH2CH2(CF2CF2). n Compounds of CH2CH2I, where n = 1, 2, 3; (2) After the addition reaction is completed, no post-processing is performed. Solvent and strong base are directly added to the distillation vessel to carry out the de-HI reaction and simultaneously distill the fluorinated diene compound of the product. The addition reaction is carried out at a temperature of 180–220°C for 5–8 hours, involving ethylene and I(CF2CF2). n The molar ratio of I is 3 to 5:1; In step (2), the de-HI reaction temperature is 80–120°C, and the strong base reacts with ICH2CH2(CF2CF2). n The molar ratio of CH2CH2I is 1.2 to 1.5:1; The general chemical formula of the fluorinated diene compound is CH2=CH(CF2CF2). n CH=CH2,n=1,2,3.

2. The method for preparing a fluorinated diene compound according to claim 1, characterized in that, The distillation vessel is made of Hastelloy C276.

3. The method for preparing a fluorinated diene compound according to claim 1, characterized in that, The preparation method uses I(CF2CF2) n I is obtained by reacting tetrafluoroethylene with iodine.

4. The method for preparing a fluorinated diene compound according to claim 3, characterized in that, The reaction temperature of tetrafluoroethylene with iodine is 150–180℃, the reaction time is 1–3 h, and the molar ratio is 1.2–3.5:

1.

5. The method for preparing a fluorinated diene compound according to claim 1, characterized in that, In step (2), the solvent is one or more of ethanol, ethylene glycol, and isopropanol.

6. The method for preparing a fluorinated diene compound according to claim 1, characterized in that, In step (2), the strong base is NaOH, KOH or triethylamine.

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