A continuous process for the synthesis of cyclopentadiene trimer

Abstract

This invention provides a continuous synthesis method for cyclopentadiene trimer, comprising the following steps: mixing dicyclopentadiene, an organic solvent, and a Lewis acid catalyst, and then feeding the mixture into a tubular reactor for reaction, followed by sequential atmospheric distillation and vacuum distillation to obtain the cyclopentadiene trimer; the organic solvent is one or more selected from cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile; the Lewis acid catalyst is one or more selected from aluminum trichloride, ferric chloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride. This invention, by selecting appropriate solvents and Lewis acids, enables the reaction to occur with higher selectivity and reduces side reactions. Subsequent purification by vacuum distillation can reduce the decomposition of TCPD and the formation of other byproducts during distillation.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and particularly relates to a continuous synthesis method for cyclopentadiene trimer. Background Technology

[0002] Hydrogenated cyclic olefin ring-opening polymers, as a type of thermoplastic polymer with many advantages such as excellent heat resistance, high transparency, low birefringence, low water absorption, and high rigidity, have replaced glass and other plastic packaging materials in recent years and are widely used in medical, pharmaceutical, and cosmetic fields such as pre-filled syringes, plastic vials, infusion bags, contrast agents, and hyaluronic acid packaging bottles.

[0003] However, to ensure that the material has a high refractive index and a high Abbe number after molding, appropriate monomers must be selected for polymerization. Among them, cyclopentadiene trimer (TCPD) can effectively improve the refractive index of the material, and its structure does not contain benzene rings, so it will not cause problems such as a decrease in the Abbe number of the material or affect color difference.

[0004] Meanwhile, cyclopentadiene trimer, as an important organic synthesis intermediate, can be used as a high-density hydrocarbon fuel after hydrogenation; the density of tetrahydrocyclopentadiene trimer is 1.04 g / cm³. 3 It has a density higher than traditional aviation kerosene (0.775 g / cm³). 3 With a yield of over 34.2%, tetrahydrocyclopentadiene trimer is the best low-cost way to improve missile speed and range, especially given the limitations of fuel tanks in military and aviation applications.

[0005] Existing synthetic methods, such as the Diels-Alder (DA) reaction route of cyclopentadiene (CPD) and dicyclopentadiene (DCPD), involve high reaction temperatures. US3701812 discloses a method for synthesizing cyclopentadiene trimers, which involves reacting at 260–310 °C and 3.2–3.8 MPa for 5–25 min, achieving a conversion rate of 40–50%. However, due to the high reaction temperature, this method not only increases energy consumption in production but also generates more other byproducts, reducing the yield. Summary of the Invention

[0006] The purpose of this invention is to provide a continuous synthesis method for cyclopentadiene trimer. The continuous synthesis method of this invention can effectively improve the yield of cyclopentadiene trimer at a lower temperature, while reducing the generation of by-products.

[0007] This invention provides a continuous synthesis method for cyclopentadiene trimer, comprising the following steps:

[0008] Dicyclopentadiene, organic solvent and Lewis acid catalyst are mixed and fed into a tubular reactor for reaction, and then subjected to atmospheric distillation and vacuum distillation in sequence to obtain cyclopentadiene trimer;

[0009] The organic solvent is one or more of cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propylbenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile;

[0010] The Lewis acid catalyst is one or more of aluminum trichloride, ferric trichloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride.

[0011] Preferably, the mass ratio of the dicyclopentadiene to the solvent is (0.5-5):1.

[0012] Preferably, the molar ratio of the dicyclopentadiene to the Lewis acid catalyst is (10-1000):1.

[0013] Preferably, the reaction temperature is 70–220°C; and the residence time in the tubular reactor is 0.5–10 hours.

[0014] Preferably, the reaction pressure is 1 to 5 MPa.

[0015] Preferably, the bottom temperature of the atmospheric distillation column is 100–250°C, and the top temperature is 50–150°C.

[0016] Preferably, the temperature of the bottom of the vacuum distillation column is 90–140°C, and the temperature of the top of the column is 50–100°C.

[0017] Preferably, the vacuum degree of the reduced pressure distillation is 1 to 20 kPa.

[0018] This invention provides a continuous synthesis method for cyclopentadiene trimer, comprising the following steps: mixing dicyclopentadiene, an organic solvent, and a Lewis acid catalyst, and then feeding the mixture into a tubular reactor for reaction, followed by sequential atmospheric and vacuum distillation to obtain the cyclopentadiene trimer; the organic solvent is one or more selected from cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile; the Lewis acid catalyst is one or more selected from aluminum trichloride, ferric chloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride. This invention, by selecting appropriate solvents and Lewis acids, can effectively improve the formation of dienophilic substrates, thereby reducing the LUMO energy of the dienophiles, resulting in higher selectivity of the reaction, reducing side reactions, and, through continuous synthesis in a tubular reactor, effectively increasing the yield of cyclopentadiene trimer at lower temperatures. Then, by using vacuum distillation to purify the product, the decomposition of TCPD and the formation of other byproducts during the distillation process can be reduced, resulting in high-purity cyclopentadiene trimer (TCPD) at the polymerization grade. Detailed Implementation

[0019] This invention provides a continuous synthesis method for cyclopentadiene trimer, comprising the following steps:

[0020] Dicyclopentadiene, organic solvent and Lewis acid catalyst are mixed and fed into a tubular reactor for reaction, and then subjected to atmospheric distillation and vacuum distillation in sequence to obtain cyclopentadiene trimer;

[0021] The organic solvent is one or more of cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propylbenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile;

[0022] The Lewis acid catalyst is one or more of aluminum trichloride, ferric trichloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride.

[0023] In this invention, the dicyclopentadiene trimer has the structure shown in Formula I.

[0024]

[0025] In this invention, the purity of the dicyclopentadiene is preferably 95% or more, more preferably 98% or more, and most preferably 99.5% or more.

[0026] In this invention, the organic solvent is preferably one or more of cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile; the Lewis acid catalyst is preferably one or more of aluminum trichloride, ferric chloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride.

[0027] In this invention, the mass ratio of dicyclopentadiene to solvent is preferably (0.5-5):1, more preferably (1-4):1, such as 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, and preferably within the range of any of the above values ​​as the upper or lower limit; the molar ratio of dicyclopentadiene to Lewis acid catalyst is preferably (10-1000):1, more preferably (20-100):1, such as 10:1, 20:1, 50:1, 100:1, 200:1, 300:1, 400:1, 500:1, 600:1, 700:1, 800:1, 900:1, 1000:1, and preferably within the range of any of the above values ​​as the upper or lower limit.

[0028] This invention involves mixing dicyclopentadiene (DCPD) with an organic solvent and a Lewis acid, and then introducing the mixture into a tubular reactor via a liquid-phase injection pump. The reactor is pre-emptively purged with solvent to remove oxygen from the reaction system. The tubular reactor is equipped with a heating device, set at a temperature of 70–220°C; the pressure is adjusted from 1–5 MPa via a back pressure valve; and Aspen software is used to simulate and calculate the rate at which the feed liquid is pumped into the reactor, controlling the reaction time to 0.5–10 hours. After the reaction system stabilizes, samples are taken at the sampling port, and the content of each component in the product is analyzed using gas chromatography.

[0029] In this invention, the reaction temperature is preferably 70–220°C, more preferably 100–200°C, such as 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, preferably within the range of any of the above values ​​as the upper or lower limit; the reaction pressure is preferably 1–5 MPa, more preferably 2–4 MPa, most preferably 2–3 MPa; the residence time of the mixture in the tubular reactor is preferably 0.5–10 hours, more preferably 1–9 hours, such as 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, preferably within the range of any of the above values ​​as the upper or lower limit.

[0030] After the reaction is completed, the product is transported to an atmospheric distillation column for preliminary runoff removal of light components. Specifically, this removal involves removing residual cyclopentadiene, organic solvents, and other low-boiling-point components from the product. Then, the product is separated by vacuum distillation. The distilled components are collected at the top of the column and detected by gas chromatography to obtain high-purity cyclopentadiene trimer.

[0031] In this invention, the bottom temperature of the atmospheric distillation column is preferably 100–250°C, more preferably 120–150°C, such as 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, preferably within the range of any of the above values ​​as the upper or lower limit; the top temperature is preferably 50–150°C, more preferably 100–120°C, such as 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, preferably within the range of any of the above values ​​as the upper or lower limit.

[0032] This invention employs vacuum distillation, which effectively avoids the decomposition of reaction products at high temperatures, thereby improving product yield and purity. In this invention, the bottom temperature of the vacuum distillation column is preferably 90–140°C, more preferably 100–130°C, such as 90°C, 100°C, 110°C, 120°C, 130°C, and 140°C, preferably within a range where any of the above values ​​is the upper or lower limit. The top temperature of the vacuum distillation column is preferably 50–100°C, more preferably 60–90°C, such as 50°C, 60°C, 70°C, 80°C, and 90°C. The temperature is 100℃, preferably within the range of any of the above values ​​as the upper or lower limit; the vacuum degree of the vacuum distillation column is preferably 1 to 20 kPa, more preferably 1 to 10 kPa, such as 1 kPa, 2 kPa, 3 kPa, 4 kPa, 5 kPa, 6 kPa, 7 kPa, 8 kPa, 9 kPa, 10 kPa, 11 kPa, 12 kPa, 13 kPa, 14 kPa, 15 kPa, 16 kPa, 17 kPa, 18 kPa, 19 kPa, 20 kPa, preferably within the range of any of the above values ​​as the upper or lower limit.

[0033] This invention provides a continuous synthesis method for cyclopentadiene trimer, comprising the following steps: mixing dicyclopentadiene, an organic solvent, and a Lewis acid catalyst, and then feeding the mixture into a tubular reactor for reaction, followed by sequential atmospheric and vacuum distillation to obtain the cyclopentadiene trimer; the organic solvent is one or more selected from cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile; the Lewis acid catalyst is one or more selected from aluminum trichloride, ferric chloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride. This invention, by selecting appropriate solvents and Lewis acids, can effectively improve the formation of dienophilic substrates, thereby reducing the LUMO energy of the dienophiles, resulting in higher selectivity of the reaction, reducing side reactions, and, through continuous synthesis in a tubular reactor, effectively increasing the yield of cyclopentadiene trimer at lower temperatures. Then, by using vacuum distillation to purify the product, the decomposition of TCPD and the formation of other byproducts during the distillation process can be reduced, resulting in high-purity cyclopentadiene trimer (TCPD) at the polymerization grade.

[0034] The analysis of the samples was performed using an Agilent 8860-GC gas chromatograph with an HP-5 (30m × 32μm × 0.25um) column. The injection port temperature was 180℃, and the detector FID temperature was 250℃.

[0035] The heating conditions were as follows: initial temperature 50℃, hold for 5 min, then increase to 170℃ at 10℃ / min, then increase to 300℃ at 20℃ / min, and hold for 11 min.

[0036] To further illustrate the present invention, the following detailed description of a continuous synthesis method for cyclopentadiene trimer provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] A 2 kg solution was prepared in advance with a toluene:DCPD mass ratio of 1:1. Boron trifluoride diethyl ether with a molar ratio of DCPD:boron trifluoride diethyl ether = 500:1 was added to the solution. After mixing thoroughly, the solution was pumped into a tubular reactor at a rate of 2.7 ml / min using a liquid phase pump. The temperature inside the tubular reactor was 190℃, and the pressure was set to 1 MPa through a back pressure valve. The raw material solution was sampled and analyzed after 30 minutes in the reactor.

[0039] Example 2

[0040] The reaction product was prepared using the same method as in Example 1, except that the solution mixed with DCPD was replaced with propylbenzene.

[0041] Example 3

[0042] The reaction product was prepared using the same method as in Example 1, except that the solution mixed with DCPD was replaced with a mixture of acetonitrile and benzene in a ratio of 3:1.

[0043] Example 4

[0044] The reaction product was prepared using the same method as in Example 2, except that the Lewis acid mixed therein was replaced with aluminum trichloride.

[0045] Example 4

[0046] The reaction product was prepared using the same method as in Example 2, except that the Lewis acid mixed therein was replaced with a mixed catalyst of aluminum trichloride and zinc chloride.

[0047] Example 5

[0048] The reaction product was prepared using the same method as in Example 1, except that the reaction temperature was changed to 150°C and the residence time in the reactor was changed to 90 min.

[0049] Example 6

[0050] The reaction product was prepared using the same method as in Example 1, except that the reaction pressure was changed to 3 MPa.

[0051] Comparative Example 1

[0052] The reaction product was prepared using the same method as in Example 1, except that Lewis acid was not added during the reaction.

[0053] Comparative Example 2

[0054] The reaction product was prepared using the same method as in Example 1, except that the solution mixed with DCPD was replaced with N,N-dimethylformamide (DMF).

[0055] The results of the continuous synthesis are shown in Table 1.

[0056] Table 1. Mass percentage of each component of TCPD synthesized under different conditions.

[0057]

[0058] Example 7

[0059] The product prepared in Example 1 was placed in the reboiler of a distillation column. The reboiler temperature was set at 135°C, the top temperature at 122°C, and the reflux ratio at 1:1. Cyclopentadiene and solvent were collected from the top of the product; this portion of the product could be recovered and used in the synthesis of TCPD. The reboiler product was then transferred to a vacuum distillation column. The reboiler temperature was set at 110°C, the top temperature at 65°C, and the vacuum degree at 5 kPa. A reflux ratio of 3:1 was used for collection. The remaining dicyclopentadiene was collected, and polymer-grade cyclopentadiene trimer was obtained from the top of the column. The collected dicyclopentadiene could be recovered and used in the synthesis reaction.

[0060] Comparative Example 3

[0061] The product prepared in Example 1 was placed in the reboiler of a distillation column. The reboiler temperature was set to 135°C, the top temperature to 122°C, and the reflux ratio to 1:1. Cyclopentadiene and solvent were obtained from the top of the column. Then, the reboiler temperature was raised to 210°C, and the top temperature was controlled at 190°C to obtain cyclopentadiene trimer.

[0062] The obtained cyclopentadiene trimer was also analyzed by gas chromatography, and the results are shown in Table 2.

[0063] Table 2. Mass percentages of each component in the products of Example 7 and Comparative Example 1.

[0064] main components Example 7 Comparative Example 3 cyclopentadiene 0％ 0.009％ exo-DCPD 0.164％ 0.314％ endo-DCPD 0.175％ 0.266％ TCPD (Structure Total) 99.543％ 98.142％ Tetramers and other byproducts 0.118％ 1.269％

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for the continuous synthesis of cyclopentadiene trimer, comprising the following steps: Dicyclopentadiene, organic solvent and Lewis acid catalyst are mixed and fed into a tubular reactor for reaction, and then subjected to atmospheric distillation and vacuum distillation in sequence to obtain cyclopentadiene trimer; The organic solvent is one or more of cyclohexane, n-heptane, dichloromethane, benzene, toluene, xylene, ethylbenzene, propylbenzene, o-dichlorobenzene, ethyl acetate, isobutyl acetate, and acetonitrile; The Lewis acid catalyst is one or more of aluminum trichloride, ferric trichloride, boron trifluoride diethyl ether, methyl aluminum dichloride, and zinc chloride; The mass ratio of dicyclopentadiene to solvent is (0.5~5):1, the reaction temperature is 70~220℃, the residence time in the tubular reactor is 0.5~10 hours, and the reaction pressure is 1~5MPa.

2. The continuous synthesis method according to claim 1, characterized in that, The molar ratio of dicyclopentadiene to Lewis acid catalyst is (10~1000):

1.

3. The continuous synthesis method according to claim 1, characterized in that, The temperature of the bottom of the atmospheric distillation column is 100~250℃, and the temperature of the top of the column is 50~150℃.

4. The continuous synthesis method according to claim 3, characterized in that, The temperature of the bottom of the vacuum distillation column is 90~140℃; the temperature of the top of the column is 50~100℃.

5. The continuous synthesis method according to claim 4, characterized in that, The vacuum degree of the reduced pressure distillation is 1~20 kPa.

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