A process for the preparation of high purity trans-4-propionylcyclohexylbenzene

Abstract

The application discloses a preparation method of high-purity trans-4-propionylcyclohexylbenzene, and belongs to the technical field of liquid crystal material preparation. The method is based on dynamic synergy of three-stage gradient temperature control, seed addition in batches and intermittent stirring, and in a single petroleum ether solvent system, crystal growth is induced through ultralow-temperature cyclic crystallization and precise temperature control; in combination with a matching filter-drying integrated machine, continuous operation of low-temperature solid-liquid separation and vacuum drying is realized. The application significantly improves the purity and yield stability of the product, and one-time high-purity crystals are obtained, overcoming the problems of incomplete impurity separation, high energy consumption and large batch fluctuation in the traditional process, and simultaneously adapting to the industrial production demand, and providing a green and efficient high-purity preparation path for liquid crystal intermediates.

Description

Technical Field

[0001] This invention relates to the field of organic compound crystallization technology and liquid crystal material preparation technology, and to a method for preparing a key raw material for trans-4-(4-n-propylcyclohexyl)phenol, a liquid crystal intermediate, specifically a method for preparing high-purity trans-4-propionylcyclohexylbenzene. Background Technology

[0002] Trans-4-propionylcyclohexylbenzene (3OP) is a core intermediate in the synthesis of liquid crystal materials, and its purity directly determines the performance of downstream products. Currently, the industrial method using aluminum trichloride catalyzing a one-step synthesis of propionyl chloride, cyclohexene, and benzene results in a crude product with significantly insufficient effective 3OP content and contamination with various cis isomers, unreacted raw materials, and multi-substituted byproducts. Directly using this low-purity crude product for subsequent reactions not only leads to low raw material utilization and increased energy consumption but also causes equipment malfunctions due to impurity deposition.

[0003] While existing ultra-low temperature recrystallization processes can achieve partial purification, they still have shortcomings that need improvement: First, process parameters rely excessively on operational experience, and the solvent ratio and seed control lack quantitative standards, resulting in poor product yield stability; second, traditional mixed solvent systems suffer from low crystallization efficiency and loose crystal structure, making it difficult to achieve efficient separation of impurities; third, conventional temperature control technology cannot accurately maintain the ultra-low temperature crystallization environment required for 3OP, leading to frequent occurrences of impurity encapsulation in crystals.

[0004] Although existing technologies have improved purification efficiency through solvent combination optimization, they have failed to overcome the technical barriers of synergistic technology involving seed-stage induction, temperature gradient control, and dynamic stirring strategies. In addition, the separation and drying steps involved in the process need to be carried out on different equipment, which makes the material transfer and separation dehydration operations more complicated and further reduces production efficiency.

[0005] To address the problems of incomplete impurity separation, insufficient process controllability, and high energy and material losses in existing technologies, a high-purity trans-4-propionylcyclohexylbenzene preparation technology integrating three-stage gradient temperature control, multi-stage seed addition, and vacuum filtration and drying is urgently needed. Summary of the Invention

[0006] The purpose of this invention is to address the technical problems of low yield, insufficient purity, high energy consumption, and poor batch stability in existing trans-4-propionylcyclohexylbenzene preparation processes. This invention provides a data-driven, ultra-low temperature recrystallization synergistic optimization method. Through the dynamic coupling of phased seed crystal addition, gradient temperature control, and intermittent stirring, it achieves efficient preparation of high-purity trans-4-propionylcyclohexylbenzene crystals (≥85.0%), reducing energy consumption and adapting to 50-500 kg-scale industrial production, thus promoting the upgrading of green manufacturing technology for liquid crystal intermediates. A second objective of this invention is the design of an integrated vacuum filtration and drying machine to complement the improved process, further enhancing production efficiency.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing high-purity trans-4-propionylcyclohexylbenzene, comprising the following steps:

[0008] a) Solvent mixing: Mix crude trans-4-propionylcyclohexylbenzene with petroleum ether at a volume ratio of 1:0.6 to 1.5, and stir until completely dissolved to form a homogeneous solution;

[0009] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min, seed crystals are added in batches, and stirring is started. The amount of seed crystals added is 2.5 to 10% of the crude trans-4-propionylcyclohexylbenzene. The temperature is then further cooled to -40℃±2℃ and maintained for 50-60 min.

[0010] c) Gradient pre-crystallization strengthening:

[0011] First stage: Heat to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchoring for 20min at a stirring speed of 100rpm±10rpm; cool to -35℃±1℃ at a rate of 1℃ / min, stir with anchoring for 20min at a stirring speed of 100rpm±10rpm; repeat the above operation process for a total of 5 heating and cooling operations.

[0012] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 50-60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0013] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash solution accounting for 30%~50% of the crude trans-4-propionylcyclohexylbenzene mass.

[0014] e) Vacuum drying: The filter cake is dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain trans-4-propionylcyclohexylbenzene crystals with a purity ≥85.0%.

[0015] As a further aspect of the present invention: in step a), the petroleum ether is a reagent-grade solvent with a distillation range of 90℃ to 120℃; when the purity of the crude trans-4-propionylcyclohexylbenzene is <60%, it needs to be pretreated by washing with water. The treatment steps are as follows: mix the crude product with deionized water at a mass ratio of 1:3, shake for 10 minutes and separate into layers, take the organic phase and remove the solvent under reduced pressure until the water content is ≤0.5wt%.

[0016] As a further embodiment of the present invention: in step b), the seed crystal is prepared by dissolving pure trans-4-propionylcyclohexylbenzene in petroleum ether at a volume ratio of 1:2 and recrystallizing at -20℃ to -25℃; the purity of the pure trans-4-propionylcyclohexylbenzene is ≥90% and the particle size is 50 to 100 μm; the solvent consists only of petroleum ether and has a boiling range of 90℃ to 120℃.

[0017] The seed crystals are added in batches as described in step b): the seed crystals are added in three equal amounts, with a total addition amount of 2.5% to 10% of the crude trans-4-propionylcyclohexylbenzene mass, with an interval of 5 minutes between each addition; the stirring is carried out using an anchor stirrer with a speed of 100 rpm ± 10 rpm and a stirring power of 0.5 to 1.5 kW / m³.

[0018] As a further embodiment of the present invention: steps d) and e) are operated using an integrated vacuum filtration and drying machine, the integrated vacuum filtration and drying machine including a first reaction chamber, a connecting pipe fixedly connected to the bottom end of the first reaction chamber, a second reaction chamber fixedly connected to the bottom end of the connecting pipe, and a discharge port fixedly connected to the bottom end of the second reaction chamber. The first reaction chamber is subjected to vacuum filtration by a vacuum filtration mechanism, and the second reaction chamber is subjected to drying by a drying mechanism.

[0019] As a further embodiment of the present invention: the filtration mechanism includes a filtration bottle disposed within the inner cavity of the first reaction chamber. A drain pipe is fixedly connected to the bottom end of the filtration bottle, and a first suction pipe is fixedly connected to one side of the filtration bottle. A valve is installed on the outer wall of the drain pipe. The drain pipe and the first suction pipe extend to the outside of the first reaction chamber. A connecting seat is fixedly connected to the top end of the filtration bottle. A connecting block is fixedly connected to the inner wall of the connecting seat. A filter plate is fixedly connected to the outer wall of the connecting block. A movable cylinder is disposed above the connecting seat. A movable tube is fixedly connected to the top end of the movable cylinder. The movable tube is slidably connected to the first reaction chamber. A hopper is fixedly connected to the top end of the movable tube. A horizontal plate is fixedly connected to the outer wall of the movable tube. A first motor is installed at the top end of the first reaction chamber. A first threaded rod is connected to the output end of the first motor and passes through the horizontal plate.

[0020] As a further embodiment of the present invention: the drying mechanism includes a second motor, which is mounted on one side of the first reaction chamber. A second threaded rod is connected to the output end of the second motor. A shield extending from the connecting pipe is slidably connected inside the connecting pipe. The second threaded rod passes through the shield. A pusher extending into the inner cavity of the first reaction chamber is fixedly connected to the outer wall of the shield. A through hole is provided on the outer wall of the shield. A second suction pipe and an inlet pipe are fixedly connected to one side of the outer wall of the second reaction chamber. The bottom end of the inner wall of the second reaction chamber is fixedly located at the top end of the discharge port. A square frame is connected, and a constant-temperature electric heater is provided on the inner wall of the square frame. A rotating plate is rotatably connected inside the square frame, and a baffle is rotatably connected to the inner wall of the discharge port. A spur gear is fixedly connected to one end of both the rotating plate and the baffle. A toothed rod is slidably connected to the discharge port and the inside of the square frame. A third motor is installed on one outer wall of the discharge port. A third threaded rod is connected to the output end of the third motor and passes through the toothed rod. The spur gear contacts the toothed rod. A partition 615 is fixedly connected to the top of the toothed rod and extends into the inner cavity of the air inlet pipe.

[0021] As a further embodiment of the present invention: the inner wall of the movable cylinder is in contact with the outer wall of the filter plate, the outer wall of the movable cylinder is in contact with the inner wall of the connecting seat, both the inner and outer walls of the movable cylinder are provided with sealing rings, and the outer wall of the horizontal plate is provided with a first threaded hole, which matches the first threaded rod.

[0022] As a further embodiment of the present invention: the outer wall of the shielding frame is provided with a second threaded hole, which matches the second threaded rod.

[0023] As a further embodiment of the present invention: the rack is L-shaped and the bottom end of the lower horizontal bar is provided with a third threaded hole, the third threaded hole is matched with the third threaded rod, and the outer wall of the upper vertical bar of the rack is provided with a tooth groove, the tooth groove meshing with the spur gear.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. The method for preparing high-purity trans-4-propionylcyclohexylbenzene described in this invention significantly improves purification efficiency and crystal quality. This invention utilizes a dynamic synergy of gradient temperature control via cyclic operation within a -40℃ to -25℃ range and intermittent anchor stirring to purify crude trans-4-propionylcyclohexylbenzene with an initial content of 60% to over 85.0% in a single step, achieving a yield of 76.6%, an absolute improvement of 14.2 percentage points compared to the traditional process (yield 62.4%). This meets the 24-month storage stability requirements for liquid crystal materials and completely solves the technical bottleneck of traditional processes requiring multiple purifications and prone to deterioration after storage.

[0026] 2. The method for preparing high-purity trans-4-propionylcyclohexylbenzene described in this invention achieves breakthroughs in industrial adaptability and production economy. The flexible throughput design of 50-500 kg seamlessly adapts to GLR series crystallizers (50-1000L specifications), achieving precise temperature control of ±1℃ and accurate matching of stirring power from 0.5 kW / m³ to 1.5 kW / m³. Adding seed crystals in three equal increments (5 min apart) avoids localized oversaturation and reduces impurity encapsulation. It achieves batch-to-batch purity variation ≤1.5% (RSD=0.8%) and yield fluctuation standard deviation ≤1.2%, breaking through the industry's 5% fluctuation threshold.

[0027] 3. Green environmental protection and industrial chain synergy optimization produce high-purity products (≥85.0%), and MSDS-certified petroleum ether solvent is used throughout the process, with VOCs emissions <10mg / m³.

[0028] 4. A combined filtration and drying machine was designed to complement the improved process. This equipment incorporates a filtration mechanism and a drying mechanism. The movable cylinder is inserted into the inner wall of the connecting seat, and the filter plate enters the inner cavity of the movable cylinder, forming a cavity between the movable cylinder and the filter plate. The solution prepared in step c) is poured into the cavity, and the first suction pipe removes the air from the filtration bottle, thus performing the filtration operation. After completion, the liquid in the filtration bottle can be discharged through the drain pipe by opening the valve. After filtration is completed, the first motor is started to move the movable cylinder above the connecting seat. At this time, the filter cake is located at the top of the filter plate. Then, petroleum ether pre-cooled to -10℃ can be poured into the hopper and poured onto the filter cake through the movable pipe. The filter cake falls to the top of the rotating plate for drying. This design facilitates integrated filtration and drying operations in one machine, reducing transfer links and equipment footprint, and further improving operational efficiency. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the integrated vacuum filtration and drying machine described in this invention;

[0030] Figure 2 This is a schematic diagram of the internal structure of the first reaction chamber of the integrated vacuum filtration and drying machine of the present invention;

[0031] Figure 3 This is a schematic diagram of the internal structure of the filtration flask of the integrated filtration and drying machine described in this invention;

[0032] Figure 4 This is a schematic diagram of the internal structure of the second reaction chamber of the integrated filtration and drying machine of the present invention;

[0033] Figure 5 This is a schematic diagram of the shielding frame of the integrated vacuum filtration and drying machine described in this invention;

[0034] Figure 6 This is a schematic diagram of the installation of the toothed rod of the integrated vacuum filtration and drying machine described in this invention;

[0035] Figure 7 This is a schematic diagram of the toothed rod of the integrated vacuum filtration and drying machine described in this invention.

[0036] In the diagram: 1. First reaction chamber; 2. Connecting pipe; 3. Second reaction chamber; 4. Discharge port; 5. Vacuum filtration mechanism; 501. Vacuum filtration flask; 502. Connecting seat; 503. Drain pipe; 504. Valve; 505. First suction pipe; 506. Hopper; 507. Movable pipe; 508. Movable cylinder; 509. Horizontal plate; 510. First motor; 511. First threaded rod; 512. Connecting block; 513. Filter plate; 6. Drying mechanism; 601. Second motor; 602. Second threaded rod; 603. Baffle frame; 604. Push frame; 605. Through hole; 606. Second exhaust pipe; 607. Inlet pipe; 608. Square frame; 609. Rotating plate; 610. Baffle; 611. Spur gear; 612. Third motor; 613. Third threaded rod; 614. Gear rack; 615. Partition plate; 7. Sealing ring. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0038] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," "linked," and "set up" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. The following describes embodiments of the invention based on its overall structure. Example 1

[0039] a) Solvent mixing: Take 20g of crude 3OP with a purity of 58.2% and mix it with 20mL of petroleum ether at a volume ratio of 1:1. Stir until completely dissolved to form a homogeneous solution.

[0040] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with equal amounts added in three separate additions, and stirring is started. The total amount added is 1g (5% of the crude mass), with each addition 5min apart. An anchor stirrer is used for stirring at a speed of 100rpm±10rpm and a stirring power of 0.5kw / m³. The temperature is then further reduced to -40℃±2℃ and held for 60min.

[0041] c) Gradient pre-crystallization strengthening:

[0042] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0043] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0044] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 50% (10g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0045] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain 10.15 g of product with a purity of 87.8% and a yield of 76.6% (100% RH).

[0046] Please refer to this carefully. Figures 1 to 3 Steps d) and e) are performed using an integrated vacuum filtration and drying machine. The integrated vacuum filtration and drying machine includes a first reaction chamber 1, with a connecting pipe 2 fixedly connected to the bottom of the first reaction chamber 1. A second reaction chamber 3 is fixedly connected to the bottom of the connecting pipe 2, and a discharge port 4 is fixedly connected to the bottom of the second reaction chamber 3. The first reaction chamber 1 undergoes vacuum filtration via a vacuum filtration mechanism 5, and the second reaction chamber 3 undergoes drying via a drying mechanism 6. The vacuum filtration mechanism 5 includes a vacuum filtration bottle 501, which is located within the inner cavity of the first reaction chamber 1. A drain pipe 503 is fixedly connected to the bottom of the vacuum filtration bottle 501, and a first suction pipe 505 is fixedly connected to one side of the vacuum filtration bottle 501. A valve 504 is installed on the outer wall of the drain pipe 503. The drain pipe 503 and the first... A suction pipe 505 extends to the outside of the first reaction chamber 1. A connecting seat 502 is fixedly connected to the top of the filtration bottle 501. A connecting block 512 is fixedly connected to the inner wall of the connecting seat 502. A filter plate 513 is fixedly connected to the outer wall of the connecting block 512. A movable cylinder 508 is provided above the connecting seat 502. A movable tube 507 is fixedly connected to the top of the movable cylinder 508. The movable tube 507 is slidably connected to the first reaction chamber 1. A hopper 506 is fixedly connected to the top of the movable tube 507. A horizontal plate 509 is fixedly connected to the outer wall of the movable tube 507. A first motor 510 is installed at the top of the first reaction chamber 1. A first threaded rod 511 is connected to the output end of the first motor 510. The first threaded rod 511 passes through the horizontal plate 509.

[0047] In this embodiment: During filtration, the first motor 510 is started, which drives the first threaded rod 511 to rotate. The rotation of the first threaded rod 511 causes the horizontal plate 509 to move. The movement of the horizontal plate 509 causes the hopper 506, the movable tube 507, and the movable cylinder 508 to move synchronously. The movable cylinder 508 moves and inserts into the inner wall of the connecting seat 502. The filter plate 513 enters the inner cavity of the movable cylinder 508, forming a cavity between the movable cylinder 508 and the filter plate 513. The solution prepared in step c) is poured into the hopper. Inside 506, the air enters the cavity through the movable tube 507. The first suction tube 505 removes the air from the filtration bottle 501, thus performing the filtration operation. After completion, the liquid in the filtration bottle 501 can be discharged through the drain tube 503 by opening the valve 504. After filtration is completed, the first motor 510 is started to move the movable cylinder 508 to the top of the connecting seat 502. At this time, the filter cake is located at the top of the filter plate 513. Then, petroleum ether pre-cooled to -10℃ can be poured into the hopper 506 and poured onto the filter cake through the movable tube 507.

[0048] Please refer to this carefully. Figures 4 to 7 The drying mechanism 6 includes a second motor 601, which is mounted on one side of the first reaction chamber 1. The output end of the second motor 601 is connected to a second threaded rod 602. A shielding frame 603 extending out of the connecting pipe 2 is slidably connected inside the connecting pipe 2. The second threaded rod 602 passes through the shielding frame 603. A pusher frame 604 extending into the inner cavity of the first reaction chamber 1 is fixedly connected to the outer wall of the shielding frame 603. A through hole 605 is opened on the outer wall of the shielding frame 603. A second suction pipe 606 and an inlet pipe 607 are fixedly connected to one side of the outer wall of the second reaction chamber 3. A square frame 608 is fixedly connected to the bottom of the inner wall of the second reaction chamber 3 at the top of the discharge port 4. A constant temperature electric heater is provided on the inner wall of the rectangular frame 608; a rotating plate 609 is rotatably connected inside the rectangular frame 608; a baffle 610 is rotatably connected to the inner wall of the discharge port 4; a spur gear 611 is fixedly connected to one end of both the rotating plate 609 and the baffle 610; a toothed rod 614 is slidably connected between the discharge port 4 and the interior of the rectangular frame 608; a third motor 612 is installed on one outer wall of the discharge port 4; a third threaded rod 613 is connected to the output end of the third motor 612; the third threaded rod 613 passes through the toothed rod 614; the spur gear 611 contacts the toothed rod 614; a partition 615 is fixedly connected to the top of the toothed rod 614; the partition 615 extends into the inner cavity of the air inlet pipe 607.

[0049] In this embodiment: After rinsing the filter cake, the second motor 601 is started. The operation of the second motor 601 drives the second threaded rod 602 to rotate. The rotation of the second threaded rod 602 drives the shielding frame 603 to move. The displacement of the shielding frame 603 drives the pushing frame 604 to move. The pushing frame 604 contacts the filter cake and pushes the filter cake off the filter plate 513 and into the connecting pipe 2. At this time, the displacement of the shielding frame 603 drives the through hole 605 to move into the inner cavity of the connecting pipe 2, opening the connecting pipe 2. The filter cake enters the second reaction chamber 3 through the connecting pipe 2 and falls to the top of the rotating plate 609. Then, the second motor 601 drives the shielding frame 603 to reset and close the connecting pipe 2. The second exhaust pipe 606 extracts the gas in the second reaction chamber 3 to form a vacuum of -0.09MPa. The constant temperature electric heater set on the inner wall of the square frame 608 operates, so that the filter cake can be dried for 4 hours at a temperature of 25℃±2℃. After drying is completed, the third motor 612 is started. The operation of the third motor 612 drives the third threaded rod 613 to rotate. The rotation of the third threaded rod 613 drives the rack 614 to move. The movement of the rack 614 drives the spur gear 611 to rotate. The rotation of the spur gear 611 drives the rotating plate 609 and the baffle 610 to rotate synchronously. The rotation of the rotating plate 609 causes the material to fall. The rotation of the baffle 610 drives the discharge port 4 to open. The material falls through the discharge port 4. At the same time, the movement of the rack 614 drives the partition 615 to move, opening the air inlet pipe 607. Nitrogen gas enters the second reaction chamber 3 through the air inlet pipe 607, preventing outside air from entering the second reaction chamber 3 through the discharge port 4, which facilitates the integrated filtration and drying operation.

[0050] Please refer to this carefully. Figures 1 to 3 The inner wall of the movable cylinder 508 is in contact with the outer wall of the filter plate 513, and the outer wall of the movable cylinder 508 is in contact with the inner wall of the connecting seat 502. Both the inner and outer walls of the movable cylinder 508 are provided with sealing rings 7. The outer wall of the horizontal plate 509 is provided with a first threaded hole, which matches the first threaded rod 511.

[0051] In this embodiment: the first motor 510 drives the first threaded rod 511 to rotate, the rotation of the first threaded rod 511 drives the horizontal plate 509 to move, the displacement of the horizontal plate 509 drives the hopper 506, the movable tube 507 and the movable cylinder 508 to move synchronously, the movable cylinder 508 is inserted into the inner wall of the connecting seat 502, the filter plate 513 enters the inner cavity of the movable cylinder 508, a cavity is formed between the movable cylinder 508 and the filter plate 513, and the sealing ring 7 is used to improve the sealing between the movable cylinder 508 and the connecting seat 502 and the filter plate 513 respectively.

[0052] Please refer to this carefully. Figures 4 to 7 The outer wall of the shield 603 is provided with a second threaded hole, which matches the second threaded rod 602.

[0053] In this embodiment: the second motor 601 drives the second threaded rod 602 to rotate, the rotation of the second threaded rod 602 drives the shielding frame 603 to move, and the movement of the shielding frame 603 drives the pusher frame 604 to move.

[0054] Please refer to this carefully. Figures 4 to 7 The rack 614 is L-shaped and the bottom end of the lower crossbar is provided with a third threaded hole, which matches the third threaded rod 613. The outer wall of the upper vertical rod of the rack 614 is provided with a tooth groove, which meshes with the spur gear 611.

[0055] In this embodiment: the third motor 612 drives the third threaded rod 613 to rotate, the rotation of the third threaded rod 613 drives the rack 614 to move, the movement of the rack 614 drives the spur gear 611 to rotate, and the rotation of the spur gear 611 drives the rotating plate 609 and the baffle 610 to rotate synchronously. Example 2

[0056] a) Solvent mixing: Take 500 kg of 3OP crude product with a purity of 58.5% and mix it with 400 L of petroleum ether (volume ratio 1:0.8). Stir until completely dissolved to form a homogeneous solution.

[0057] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with equal amounts added in three separate additions, and stirring is started. The total amount added is 5% (25kg) of the crude mass, with each addition 5min apart. An anchor stirrer is used for stirring at a speed of 100rpm±10rpm and a stirring power of 1.2kw / m³. The temperature is then further reduced to -40℃±2℃ and held for 60min.

[0058] c) Gradient pre-crystallization strengthening:

[0059] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0060] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0061] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 40% (200kg) of the crude trans-4-propionylcyclohexylbenzene mass.

[0062] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain a product with a purity of 86.7% and a yield of 75.3% (100% RH).

[0063] The equipment used is the same as in Example 1, and will not be described again here. Example 3

[0064] a) Solvent mixing: Take 20g of crude 3OP with a purity of 60.0% and mix it with 12mL of petroleum ether at a volume ratio of 1:0.6. Stir until completely dissolved to form a homogeneous solution.

[0065] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with the seed crystals added in three equal amounts, the total amount added being 5% (1g) of the crude mass, with each addition 5min apart. An anchor stirrer is used for stirring, with a speed of 100rpm±10rpm and a stirring power of 1.5kw / m³. The temperature is then further cooled to -40℃±2℃ and held for 60min.

[0066] c) Gradient pre-crystallization strengthening:

[0067] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0068] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0069] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 30% (6g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0070] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain 8.92 g of product with a purity of 85.6% and a yield of 70.5% (100% RH).

[0071] The equipment used is the same as in Example 1, and will not be described again here. Example 4

[0072] a) Solvent mixing: Same as step a) in Example 1;

[0073] b) Low-temperature pre-crystallization: Same as step b) in Example 1;

[0074] c) Gradient pre-crystallization strengthening: Same as step c) in Example 1;

[0075] d) Low-temperature solid-liquid separation: The filtration mechanism in the integrated filtration and drying machine ( Figure 2 The filter cake was pre-cooled to -10℃ (refrigerated for 30 minutes) using petroleum ether for rinsing. Filtration was performed using a vacuum filtration and drying integrated machine at -10℃±2℃. Filtration pressures were set to -0.08MPa, -0.09MPa, and -0.10MPa for testing. The surface temperature of the filter cake was monitored throughout the process.

[0076] At a pressure of -0.08 MPa, the filtration time was 7.8 minutes, and the filter cake remained intact.

[0077] At a pressure of -0.09 MPa, the filtration time was 5.2 minutes, and the filter cake remained intact.

[0078] At a pressure of -0.10 MPa, the filtration time was 4.5 minutes, and the filter cake remained intact.

[0079] Petroleum ether showed no freezing phenomenon, and the surface temperature of the filter cake was monitored to be ≤-8℃.

[0080] e) Vacuum drying: Same as step e) in Example 1. Example 5

[0081] a) Solvent mixing: Take 20g of crude 3OP with a purity of 58.2% and mix it with 20mL of petroleum ether at a volume ratio of 1:1. Stir until completely dissolved to form a homogeneous solution.

[0082] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with the seed crystals added in three equal amounts, the total amount added being 2.5% (0.5g) of the crude mass, with each addition 5min apart. An anchor stirrer is used for stirring, with a speed of 100rpm±10rpm and a stirring power of 1kw / m³. The temperature is then further reduced to -40℃±2℃ and held for 60min.

[0083] c) Gradient pre-crystallization strengthening:

[0084] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0085] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0086] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 50% (10g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0087] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain 9.25 g of product with a purity of 85.1% and a yield of 72.3% (100% RH).

[0088] The equipment used is the same as in Example 1, and will not be described again here. Example 6

[0089] a) Solvent mixing: Take 20g of crude 3OP with a purity of 58.2% and mix it with 20mL of petroleum ether at a volume ratio of 1:1. Stir until completely dissolved to form a homogeneous solution.

[0090] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with the seed crystals added in three equal amounts, the total amount added being 10% (2.0g) of the crude mass, with each addition 5min apart. An anchor stirrer is used for stirring, with a rotation speed of 100rpm±10rpm and a stirring power of 0.5-1.5kw / m³. The temperature is then further cooled to -40℃±2℃ and held for 60min.

[0091] c) Gradient pre-crystallization strengthening:

[0092] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0093] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0094] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 50% (10g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0095] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain 10.12 g of product with a purity of 86.9% and a yield of 74.8% (100% RH).

[0096] The equipment used is the same as in Example 1, and will not be described again here. Example 7

[0097] a) Solvent mixing: Take 20g of crude 3OP with a purity of 58.2% and mix it with 30mL of petroleum ether at a volume ratio of 1:1.5. Stir until completely dissolved to form a homogeneous solution.

[0098] b) Ultra-low temperature pre-crystallization: The solution obtained in step a) is cooled to -25℃±2℃ at a rate of 1℃ / min. Seed crystals are added in batches, with the seed crystals added in three equal amounts, the total amount added being 5% (1g) of the crude mass, with each addition 5min apart. An anchor stirrer is used for stirring, with a speed of 100rpm±10rpm and a stirring power of 0.5-1.5kw / m³. The temperature is then further cooled to -40℃±2℃ and held for 60min.

[0099] c) Gradient pre-crystallization strengthening:

[0100] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0101] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0102] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 50% (10g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0103] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain 8.92 g of product with a purity of 85.3% and a yield of 71.6% (100% RH).

[0104] The equipment used is the same as in Example 1, and will not be described again here.

[0105] Comparative Example 1: Seed crystals added at once

[0106] a) Solvent mixing: Take 20g of crude 3OP with a purity of 58.2% and mix it with 20mL of petroleum ether at a volume ratio of 1:1. Stir until completely dissolved to form a homogeneous solution.

[0107] b) Ultra-low temperature pre-crystallization: Cool the solution obtained in step a) to -25℃±2℃ at a rate of 1℃ / min, add seed crystals all at once, the total amount added is 5% (1g) of the crude mass; continue to cool to -40℃±2℃ and hold for 60min;

[0108] c) Gradient pre-crystallization strengthening:

[0109] First stage: Repeat the following procedure 5 times: heat up to -25℃±1℃ at a rate of 0.5℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm; then cool down to -35℃±1℃ at a rate of 1℃ / min, stir with anchor for 20min at a stirring speed of 100rpm±10rpm.

[0110] Second stage: Cool down to -40℃±1℃ at a rate of 1℃ / min and hold for 60min. Turn on anchor stirring for 2min every 10min, stirring speed 100rpm±10rpm, for a total of 5 intermittent stirrings.

[0111] d) Low-temperature solid-liquid separation: Filter under vacuum at -10℃±2℃, with a filtration pressure of -0.08MPa~-0.1MPa and a filtration time of ≤10min. The filter cake is washed three times with petroleum ether pre-cooled to -10℃, with each wash liquid amounting to 50% (10g) of the crude trans-4-propionylcyclohexylbenzene mass.

[0112] e) Vacuum drying: The filter cake was dried for 4 hours under vacuum of -0.09 MPa, temperature of 25℃±2℃, nitrogen protection, and humidity ≤10%RH to obtain a product with a purity of 83.9% and a yield of 68.1% (100% RH).

[0113] The equipment used is the same as in Example 1, and will not be described again here.

[0114] Comparative Example 2: Traditional Mixed Solvent Process

[0115] a) Solvent mixing: Take 20g of 60% purity Workshop 3OP crude product, use 20ml of petroleum ether / isopropanol (1:1) mixed solvent to dissolve it, stir until completely dissolved to form a homogeneous solution;

[0116] b) Ultra-low temperature pre-crystallization: Without adding seed crystals, the solution is directly frozen to -40°C and held for 12 hours;

[0117] c) Gradient pre-crystallization strengthening: Not performed;

[0118] d) Low-temperature solid-liquid separation: filtration was performed at 25℃±2℃ (other parameters are the same as in Example 1);

[0119] e) Vacuum drying: Same as step e) in Example 1.

[0120] The product has a purity of 78.8%, a yield of 62.4% (100% purity), and a solids content of 77.9%.

[0121] Comparative Example 3: Direct Ultra-Low Temperature Freeze-Crystallization Process

[0122] a) Solvent mixing: Same as step a) in Example 1;

[0123] b) Ultra-low temperature pre-crystallization: Without adding seed crystals, the solution is directly frozen to -40°C and held for 12 hours;

[0124] c) Gradient pre-crystallization strengthening: Not performed;

[0125] d) Low-temperature solid-liquid separation: Same as step d) in Example 1;

[0126] e) Vacuum drying: Same as step e) in Example 1.

[0127] The product yielded 7.74g after drying, with a purity of 85.2% and a yield of 55.0% (100% basis).

[0128] Comparative Example 4: Seedless Process

[0129] a) Solvent mixing: Same as step a) in Example 1;

[0130] b) Ultra-low temperature pre-crystallization: Without adding seed crystals, the solution is directly frozen to -40°C and held for 12 hours;

[0131] c) Gradient pre-crystallization strengthening: Same as step c) in Example 1;

[0132] d) Low-temperature solid-liquid separation: Same as step d) in Example 1;

[0133] e) Vacuum drying: Same as step e) in Example 1.

[0134] The product has a purity of 79.1% and a yield of 62.6% (100% purity).

[0135] Performance testing

[0136] The trans-4-propionylcyclohexylbenzene (3OP) crystals prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to product purity analysis, yield calculation (based on a percentage basis), temperature control accuracy monitoring, intermittent stirring efficiency, low-temperature filtration performance, and vacuum drying efficiency testing, using the following methods:

[0137] 1. Product purity analysis: High performance liquid chromatography (HPLC, Agilent 1260 Infinity II, C18 column 4.6×250mm, mobile phase methanol:water = 85:15 (v / v), flow rate 1.0mL / min, column temperature 30℃, detection wavelength 254nm); Calculation: main peak area normalization method, purity = (target peak area / total peak area) × 100%.

[0138] 2. Calculation of 100% yield: Yield = (mass of dried crystals × HPLC purity) / (mass of crude product × initial purity of crude product) × 100%.

[0139] 3. Temperature control accuracy monitoring: The multi-channel temperature recorder (Fluke 2680A) collects temperature data in real time during the gradient cycle (-40℃↔-25℃↔-35℃) and calculates the ±1℃ deviation compliance rate.

[0140] 4. Intermittent stirring efficiency: The consistency of the particle size distribution between the seed crystals (50-100μm) and the product crystals was compared using a laser particle size analyzer (Malvern Mastersizer 3000).

[0141] 5. Low-temperature filtration performance: Filtration time: The pressure sensor (-0.10MPa to -0.08MPa) records the time taken to reach the specified vacuum level; Filter cake temperature stability: The infrared thermal imager (FLIR T540) monitors the surface temperature difference of the filter cake during the rinsing process (required ≤±2℃).

[0142] 6. Vacuum drying efficiency: The online moisture analyzer (Mettler Toledo C30S) monitors the drying endpoint (humidity ≤10%RH) and records the time to reach the target.

[0143] The performance test results are shown in Table 1 below:

[0144] Table 1: Test Results of Process Performance in the Preparation of Trans-4-Propionylcyclohexylbenzene

[0145] In summary, this invention systematically overcomes the bottlenecks of traditional purification processes for trans-4-propionylcyclohexylbenzene through a three-stage gradient temperature control cycle, dynamic synergy of seed addition and intermittent stirring, combined with an integrated filtration and drying system. This achieves efficient preparation of high-purity crystals (≥85.0%), overcoming technical challenges such as multiple purifications, yield fluctuations, and high energy consumption. The industrial adaptability is significantly improved, with a flexible throughput design seamlessly matching 50-500kg production. Batch-to-batch stability is enhanced through quantified process parameters. Furthermore, the use of a single petroleum ether solvent system and continuous equipment integration throughout the process reduces VOC emissions and material transfer losses, providing a green, stable, and low-consumption new manufacturing path for liquid crystal intermediates.

[0146] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A process for the preparation of high purity trans-4-propionylcyclohexylbenzene, characterized in that, The method comprises the following steps: a) solvent mixing: mixing the crude trans-4-propionylcyclohexylbenzene with petroleum ether at a volume ratio of 1:0.6-1.5, stirring until completely dissolved to form a uniform solution; b) ultra-low temperature pre-crystallization: cooling the solution obtained in step a) to -25℃±2℃ at a rate of 1℃ / min, adding crystal seeds in batches, the total amount of crystal seeds being 2.5-10 wt% of the mass of the crude trans-4-propionylcyclohexylbenzene, and continuing to cool to -40℃±2℃ and keeping for 50-60 min; c) gradient pre-crystallization strengthening: first stage: operating 5 times in the following program: increasing the temperature to -25℃±1℃ at a rate of 0.5℃ / min, anchor stirring for 20 min at a stirring speed of 100rpm±10rpm; then decreasing the temperature to -35℃±1℃ at a rate of 1℃ / min, anchor stirring for 20 min at a stirring speed of 100rpm±10rpm; second stage: further decreasing the temperature to -40℃±1℃ at a rate of 1℃ / min and keeping for 50-60 min, opening the anchor stirring for 2 min every 10 min at a stirring speed of 100rpm±10rpm, for a total of 5 times of intermittent stirring; d) low-temperature solid-liquid separation: suction filtration at an environment of -10℃±2℃, the suction filtration pressure being -0.08MPa--0.1MPa, the suction filtration time being ≤10 min, and the filter cake being rinsed with petroleum ether pre-cooled to -10℃ for 3 times, the amount of rinsing liquid for each time being 30%-50% of the mass of the crude product; e) vacuum drying: drying the filter cake under the conditions of a vacuum degree of -0.09MPa, a temperature of 25℃±2℃, nitrogen protection, and a humidity of ≤10%RH for 4h to obtain trans-4-propionylcyclohexylbenzene crystals with a purity of ≥85.0%; In the step b), the crystal seeds are added in batches, and the crystal seeds are added in equal amounts in 3 times with an interval of 5 min; the stirring is performed by using an anchor stirrer, the stirring power is 0.5-1.5kw / m³, and the rotating speed is 100rpm±10rpm; In the step a), the petroleum ether is a reagent grade solvent with a distillation range of 90℃-120℃; when the purity of the crude trans-4-propionylcyclohexylbenzene is <60%, water washing pretreatment is required, and the processing steps are as follows: mixing the crude product with deionized water at a mass ratio of 1:3, shaking for 10 min, and then separating the layers, and taking the organic phase to remove the solvent under reduced pressure until the water content is ≤0.5wt%.

2. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 1, wherein, The steps d) and e) are performed by using a suction filtration and drying integrated machine, the suction filtration and drying integrated machine comprises a first reaction tank (1), a connecting pipe (2) is fixedly connected to the bottom end of the first reaction tank (1), a second reaction tank (3) is fixedly connected to the bottom end of the connecting pipe (2), a discharge port (4) is fixedly connected to the bottom end of the second reaction tank (3), the first reaction tank (1) is subjected to suction filtration operation by a suction filtration mechanism (5), and the second reaction tank (3) is subjected to drying operation by a drying mechanism (6).

3. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 2, wherein, The suction filtering mechanism (5) comprises a suction filtering bottle (501), the suction filtering bottle (501) is arranged in the inner cavity of the first reaction box (1), the bottom end of the suction filtering bottle (501) is fixedly connected with a liquid discharge pipe (503), one side of the suction filtering bottle (501) is fixedly connected with a first air suction pipe (505), the outer wall of the liquid discharge pipe (503) is mounted with a valve (504), the liquid discharge pipe (503) and the first air suction pipe (505) extend to the outside of the first reaction box (1), the top end of the suction filtering bottle (501) is fixedly connected with a connecting seat (502), the inner wall of the connecting seat (502) is fixedly connected with a connecting block (512), the outer wall of the connecting block (512) is fixedly connected with a filter plate (513), the top of the connecting seat (502) is provided with a movable cylinder (508), the top end of the movable cylinder (508) is fixedly connected with a movable pipe (507), the movable pipe (507) is slidably connected with the first reaction box (1), the top end of the movable pipe (507) is fixedly connected with a hopper (506), the outer wall of the movable pipe (507) is fixedly connected with a horizontal plate (509), the top end of the first reaction box (1) is mounted with a first motor (510), the output end of the first motor (510) is connected with a first threaded rod (511), and the first threaded rod (511) penetrates through the horizontal plate (509).

4. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 3, wherein, The drying mechanism (6) comprises a second motor (601), the second motor (601) is installed on one side of the first reaction box (1), the output end of the second motor (601) is connected with a second threaded rod (602), the inside of the connecting pipe (2) is slidably connected with a shielding frame (603) extending out of the connecting pipe (2), the second threaded rod (602) penetrates the shielding frame (603), the outer wall of the shielding frame (603) is fixedly connected with a pushing frame (604) extending to the inner cavity of the first reaction box (1), the outer wall of the shielding frame (603) is provided with a through hole (605), one side of the outer wall of the second reaction box (3) is fixedly connected with a second air exhaust pipe (606) and an air inlet pipe (607), the inner wall bottom end of the second reaction box (3) is fixedly connected with a square frame (608) at the top end of the discharge port (4), the inside of the square frame (608) is rotatably connected with a rotating plate (609), and the inner wall of the square frame (608) is provided with a constant temperature electric heater; the inner wall of the discharge port (4) is rotatably connected with a baffle (610), one end of the rotating plate (609) and the baffle (610) is fixedly connected with a straight gear (611), the inside of the discharge port (4) and the square frame (608) is slidably connected with a toothed rod (614), one side of the outer wall of the discharge port (4) is installed with a third motor (612), the output end of the third motor (612) is connected with a third threaded rod (613), the third threaded rod (613) penetrates the toothed rod (614), the straight gear (611) is in contact with the toothed rod (614), and the top end of the toothed rod (614) is fixedly connected with a partition plate (615) extending to the inner cavity of the air inlet pipe (607).

5. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 3 wherein, The inner wall of the movable cylinder (508) is attached to the outer wall of the filter plate (513), the outer wall of the movable cylinder (508) is attached to the inner wall of the connecting seat (502), the inner wall and the outer wall of the movable cylinder (508) are provided with sealing rings (7), and the outer wall of the horizontal plate (509) is provided with a first threaded hole matched with the first threaded rod (511).

6. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 4 wherein, The outer wall of the shielding frame (603) is provided with a second threaded hole matched with the second threaded rod (602).

7. The process for the preparation of high purity trans-4-propionylcyclohexylbenzene as claimed in claim 4 wherein, The toothed rod (614) is L-shaped, the bottom end of the lower horizontal rod is provided with a third threaded hole matched with the third threaded rod (613), and the outer wall of the upper vertical rod of the toothed rod (614) is provided with a gear slot engaged with the straight gear (611).

Images