Continuous preparation method and device of 5-methyl-3-hexene-2-ketone

Abstract

The invention provides a continuous preparation method and device of 5-methyl-3-hexene-2-ketone, and relates to the technical field of organic synthesis. The method comprises the following steps: continuously introducing acetone, isobutyraldehyde and a catalyst for mixing, carrying out aldol condensation reaction, continuously discharging the obtained reaction liquid containing 5-methyl-3-hexene-2-ketone, and carrying out liquid-liquid separation to respectively obtain a water phase and an organic phase; the catalyst in the water phase is recycled and reused for the aldol condensation reaction; the organic phase is subjected to rectification, and a recovery raw material and 5-methyl-3-hexene-2-ketone are obtained respectively; the recycled raw material is used for the aldol condensation reaction. According to the method provided by the invention, efficient, stable, controllable, low-energy-consumption, economical, safe and continuous industrial production of the 5-methyl-3-hexene-2-ketone can be realized. According to the invention, the temperature and the stirring speed of aldol condensation reaction are controlled to be 50-200r / min, so that the yield, the selectivity and the purity of the product are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a continuous preparation method and device for 5-methyl-3-hexene-2-one. Background Art

[0002] 5-Methyl-3-hexen-2-one ((CH3)2CHCH=CHCOCH3) is a colorless to pale yellow liquid with a fruity and floral aroma. It is soluble in alcohol and ether but insoluble in water. It is stable at room temperature and pressure, with a boiling point of 150°C. 5-Methyl-3-hexen-2-one is an important α,β-unsaturated ketone compound. The structural characteristics of the ketone group and conjugated double bonds in its molecule make it highly active in selective reduction reactions, making it a key intermediate in the synthesis of methyl isoamyl ketone (4-methyl-2-pentanone). Methyl isoamyl ketone is a key raw material for high-end rubber antioxidants and is widely used in solvents, fragrances, and pharmaceuticals.

[0003] At present, the industrial production of 5-methyl-3-hexen-2-one mainly relies on a batch process, which usually uses isovaleraldehyde and acetone as raw materials, and obtains the product through aldol condensation, acid-catalyzed dehydration and multi-step purification. However, the traditional batch process has the following problems: (1) The process adopts batch feeding and processing, and the reaction conditions are difficult to maintain completely consistent, resulting in large fluctuations in product quality between different batches, affecting downstream applications, and low production efficiency, making it difficult to achieve continuous and stable industrial production; (2) The reaction process has high requirements for temperature, material ratio and stirring uniformity, which is prone to local overheating and increased side reactions, resulting in a large number of by-products, reduced product yield (below 40%), low selectivity (below 60%), and increased difficulty in subsequent separation and purification; (3) The batch production mode leads to high energy consumption and large solvent loss. Therefore, it is urgent to develop an efficient, stable and continuously operating process, which has important industrial application value for improving the production efficiency of 5-methyl-3-hexen-2-one, reducing energy consumption and optimizing product quality. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a continuous preparation method and apparatus for 5-methyl-3-hexen-2-one. The preparation method provided by the present invention can achieve efficient, low-energy, continuous production of 5-methyl-3-hexen-2-one, and has high product yield, high selectivity, and high purity.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a continuous preparation method of 5-methyl-3-hexen-2-one, comprising the following steps:

[0007] Continuously introducing acetone, isobutyraldehyde and a catalyst into the mixture to carry out an aldol condensation reaction to obtain a reaction solution containing 5-methyl-3-hexen-2-one; the aldol condensation reaction is carried out at a temperature of 50 to 180° C.; the aldol condensation reaction is carried out under stirring at a stirring speed of 50 to 200 r / min;

[0008] The reaction liquid containing 5-methyl-3-hexen-2-one is continuously discharged and subjected to liquid-liquid separation to obtain an aqueous phase and an organic phase respectively; the catalyst in the aqueous phase is recovered and reused in the aldol condensation reaction;

[0009] The organic phase is distilled to obtain a recovered raw material and 5-methyl-3-hexene-2-one respectively; the recovered raw material is used for the aldol condensation reaction.

[0010] Preferably, the molar ratio of isobutyraldehyde to acetone is 0.5-1.6:1.

[0011] Preferably, the catalyst comprises a nitrogen-containing compound.

[0012] Preferably, the ratio of the total mass of the acetone and isobutyraldehyde to the mass of the catalyst is 97-99:1-3.

[0013] Preferably, the aldol condensation reaction is carried out at a pressure of 0.1 to 0.3 MPa and for a time of 1 to 4 hours.

[0014] Preferably, the distillation comprises:

[0015] The organic phase is subjected to a first rectification to obtain a first distillate and a recovered raw gas; the recovered raw gas is reused in the aldol condensation reaction step;

[0016] subjecting the first distillate to a second distillation to obtain a second distillate;

[0017] The second distillate is subjected to a third distillation to obtain 5-methyl-3-hexen-2-one.

[0018] Preferably, the first distillation is carried out in a first distillation tower, the top temperature of the first distillation tower is 56-70°C, and the bottom temperature of the tower is 80-100°C;

[0019] The second distillation is carried out in a second distillation tower, the top temperature of the second distillation tower is 50-80°C, and the bottom temperature of the tower is 100-130°C;

[0020] The third distillation is carried out in a third distillation tower, the tower top temperature of the third distillation tower is 120-140°C, and the tower top temperature is 150-180°C.

[0021] The present invention also provides a device used in the continuous preparation method described in the above technical solution, comprising a synthesis reactor R01, wherein the synthesis reactor R01 is provided with a stirring device;

[0022] A liquid-liquid separator S01 whose feed port is connected to the discharge port of the synthesis reactor R01; a bottom discharge port of the liquid-liquid separator S01 is connected to a catalyst concentration tank V05, and a discharge port of the catalyst concentration tank V05 is connected to the feed port of the synthesis reactor R01;

[0023] A distillation tower whose feed inlet is connected to the organic phase outlet of the liquid-liquid separator S01.

[0024] Preferably, the distillation tower includes a first distillation tower T01, a second distillation tower T02 and a third distillation tower T03 connected in sequence;

[0025] The feed inlet of the first distillation tower T01 is connected to the organic phase outlet of the liquid-liquid separator S01, and the top discharge port of the first distillation tower T01 is connected to the feed inlet of the synthesis reactor R01 through a second delivery pump P02.

[0026] Preferably, the device further comprises a catalyst preparation tank V01, an acetone storage tank V02, an isobutyraldehyde storage tank V03 and a proportioning tank V04; the discharge ports of the catalyst preparation tank V01 and the proportioning tank V04 are connected to the feed port of the synthesis reactor R01; the discharge ports of the acetone storage tank V02 and the isobutyraldehyde storage tank V03 are connected to the feed port of the proportioning tank V04;

[0027] A first delivery pump P01 is also provided on the pipeline connecting the synthesis reactor R01 and the liquid-liquid separator S01.

[0028] The present invention adopts a continuous batch reaction, using isovaleraldehyde and acetone as raw materials, and carries out an aldol condensation reaction in the presence of a catalyst to generate a β-hydroxyketone intermediate ((CH3)2CHCH(OH)CH2COCH3), and selective dehydration is achieved under suitable catalytic conditions to obtain the target product. Compared with traditional batch processes, the continuous preparation method provided by the present invention can achieve stable feeding and output, uniform and controllable reaction conditions, few by-products, high product yield, high selectivity, and high purity, and simplifies the subsequent separation and purification process, improves the stability and economy of the overall process, and is conducive to industrial-scale production to meet the needs of high-end rubber antioxidants and fine chemical industries. The conversion rate of isobutyraldehyde is greater than 70%, and the raw material conversion rate is high. The catalyst and unreacted raw materials can be efficiently recycled and reused, while achieving stable and continuous production of 5-methyl-3-hexen-2-one, greatly improving production efficiency and process stability. The present invention controls the temperature and stirring speed of the aldol condensation reaction to 50-200 r / min, thereby improving its product yield, selectivity and purity.

[0029] Compared with the traditional batch process, the device provided by the present invention is a continuous batch device, which can realize the continuous batch reaction of 5-methyl-3-hexen-2-one and achieve efficient, stable, controllable, low-energy, economical, safe and continuous industrial production of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The device used for the continuous preparation of 5-methyl-3-hexen-2-one in the present invention comprises: V01 for a catalyst preparation tank; V02 for an acetone storage tank; V03 for an isobutyraldehyde storage tank; V04 for a proportioning tank; V05 for a catalyst concentration tank; R01 for a reactor; P01 for a first delivery pump; P02 for a second delivery pump 2; S01 for a liquid-liquid separator; T01 for a first distillation tower; T02 for a second distillation tower; and T03 for a third distillation tower.

[0031] Figure 2 Graph showing the effects of the isobutyraldehyde / acetone molar ratio and reaction time on the reaction results in the examples. DETAILED DESCRIPTION

[0032] The present invention provides a continuous preparation method of 5-methyl-3-hexen-2-one, comprising the following steps:

[0033] Continuously introducing acetone, isobutyraldehyde and a catalyst into the mixture to carry out an aldol condensation reaction to obtain a reaction solution containing 5-methyl-3-hexen-2-one; the aldol condensation reaction is carried out at a temperature of 50 to 180° C.; the aldol condensation reaction is carried out under stirring at a stirring speed of 50 to 200 r / min;

[0034] The reaction liquid containing 5-methyl-3-hexen-2-one is continuously discharged and subjected to liquid-liquid separation to obtain an aqueous phase and an organic phase respectively; the catalyst in the aqueous phase is recovered and reused in the aldol condensation reaction;

[0035] The organic phase is distilled to obtain a recovered raw material and 5-methyl-3-hexene-2-one respectively; the recovered raw material is used for the aldol condensation reaction.

[0036] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0037] The invention continuously introduces acetone, isobutyraldehyde and a catalyst into the mixture to carry out an aldol condensation reaction to obtain a reaction liquid containing 5-methyl-3-hexen-2-one.

[0038] In the present invention, the molar ratio of isobutyraldehyde to acetone is 0.5-1.6:1, and in specific embodiments can be 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1 or 1.6:1.

[0039] In the present invention, the catalyst preferably includes a nitrogen-containing compound, more preferably includes one or more of ureaacetic acid, tetramethylammonium chloride, ammonium acetate and triethylammonium chloride.

[0040] In the present invention, the ratio of the total mass of the acetone and isobutyraldehyde to the mass of the catalyst is preferably 97-99:1-3, and in specific embodiments can be 97:1, 98:1, 99:1, 97:2, 98:2, 99:2, 97:3, 98:3 or 99:3.

[0041] In the present invention, the temperature of the aldol condensation reaction is 50-180°C, and in specific embodiments, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C or 180°C; the pressure of the aldol condensation reaction is preferably 0.1-0.3 MPa, and in specific embodiments, it can be 0.1 MPa, 0.15 MPa, 0.2 MPa, 0.25 MPa or 0.3 MPa; the aldol condensation reaction is carried out under a pressure of 0.1-0.3 MPa. The reaction time is preferably 1 to 4 hours, and in specific embodiments, it can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. The aldol condensation reaction is carried out under stirring, and the stirring speed is 50 to 200 r / min, preferably 80 to 140 r / min, and in specific embodiments, it can be 50 r / min, 80 r / min, 100 r / min, 120 r / min, 140 r / min, 150 r / min, 180 r / min, or 200 r / min. The present invention controls the temperature, time, and stirring speed of the aldol condensation reaction, reduces the generation of by-products, and improves the product yield, selectivity, and purity.

[0042] After obtaining a reaction liquid containing 5-methyl-3-hexen-2-one, the present invention continuously discharges the reaction liquid containing 5-methyl-3-hexen-2-one and performs liquid-liquid separation to obtain an aqueous phase and an organic phase, respectively. The catalyst in the aqueous phase is recovered and reused in the aldol condensation reaction. In the present invention, the method for recovering the catalyst in the aqueous phase preferably includes concentrating the aqueous phase to obtain the recovered catalyst.

[0043] After obtaining the organic phase, the present invention performs rectification on the organic phase to obtain a recovered raw material and 5-methyl-3-hexene-2-one respectively; the recovered raw material is used for the aldol condensation reaction.

[0044] In the present invention, the distillation preferably includes: subjecting the organic phase to a first distillation to obtain a first distillate and a recovered raw gas, respectively; recycling the recovered raw gas to the aldol condensation reaction step; subjecting the first distillate to a second distillate to obtain a second distillate; and subjecting the second distillate to a third distillation to obtain 5-methyl-3-hexen-2-one.

[0045] In the present invention, the first distillation is preferably carried out in a first distillation tower, and the top temperature of the first distillation tower is preferably 56-70°C, and in specific embodiments it can be 56°C, 58°C, 60°C, 62°C, 65°C, 68°C or 70°C; the bottom temperature of the first distillation tower is preferably 80-100°C, and in specific embodiments it can be 80°C, 82°C, 85°C, 88°C, 90°C, 92°C, 95°C, 98°C or 100°C.

[0046] In the present invention, the second distillation is preferably carried out in a second distillation tower, the top temperature of the second distillation tower is preferably 50-80° C., and in specific embodiments, it can be 50° C., 55° C., 60° C., 65° C., 70° C., 75° C., or 80° C.; the bottom temperature of the second distillation tower is preferably 100-130° C., and in specific embodiments, it can be 100° C., 105° C., 110° C., 115° C., or 120° C. In the present invention, low-boiling impurities are separated through the second distillation.

[0047] In the present invention, the third distillation is preferably carried out in a third distillation tower. The top temperature of the third distillation tower is preferably 120-140°C, and in specific embodiments, it can be 120°C, 125°C, 130°C, 135°C, or 140°C. The top temperature of the third distillation tower is preferably 150-180°C, and in specific embodiments, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, or 180°C. In the present invention, the gas component obtained by the third distillation is liquefied to obtain 5-methyl-3-hexen-2-one. The invention separates high-boiling-point impurities through the third distillation.

[0048] The acetone and isobutyraldehyde raw materials used in the present invention are relatively widely available, providing a stable raw material supply for chemical production. Under appropriate reaction conditions, they exhibit good reactivity and are suitable for scale-up production. Furthermore, the entire preparation process utilizes a continuous synthesis process, enabling precise control of the reaction time at each stage. This facilitates controlling the aldol condensation reaction time, reducing impurity generation, and thereby improving the purity, selectivity, and yield of 5-methyl-3-hexen-2-one. Compared to traditional batch production processes, this process utilizes a continuous kettle reaction mode, enabling efficient recycling of raw materials and catalysts while achieving stable and continuous production of 5-methyl-3-hexen-2-one, significantly improving production efficiency and process stability.

[0049] The present invention also provides a device for the continuous preparation method described in the above technical solution (see the structural diagram Figure 1 ), comprising a synthesis reactor R01, wherein the synthesis reactor R01 is provided with a stirring device;

[0050] A liquid-liquid separator S01 whose feed port is connected to the discharge port of the synthesis reactor R01; a bottom discharge port of the liquid-liquid separator S01 is connected to a catalyst concentration tank V05, and a discharge port of the catalyst concentration tank V05 is connected to the feed port of the synthesis reactor R01;

[0051] A distillation tower whose feed inlet is connected to the organic phase outlet of the liquid-liquid separator S01.

[0052] The device provided by the present invention includes a synthesis reactor R01, which is provided with a feed port and a discharge port. The feed port includes a catalyst inlet and a mixed raw material inlet; and a stirring device is provided in the synthesis reactor R01.

[0053] The device provided by the present invention preferably further includes a catalyst preparation tank V01, an acetone storage tank V02, an isobutyraldehyde storage tank V03 and a proportioning tank V04; the discharge port of the catalyst preparation tank V01 is connected to the catalyst inlet of the synthesis reactor R01; the discharge port of the proportioning tank V04 is connected to the mixed raw material inlet of the synthesis reactor R01; and the discharge ports of the acetone storage tank V02 and the isobutyraldehyde storage tank V03 are both connected to the feed port of the proportioning tank V04.

[0054] The apparatus provided herein also includes a liquid-liquid separator S01, which is equipped with a feed inlet, an aqueous phase outlet, and an organic phase outlet. The feed inlet of the liquid-liquid separator S01 is connected to the outlet of the synthesis reactor R01. A first delivery pump P01 is preferably also provided on the pipeline connecting the synthesis reactor R01 and the liquid-liquid separator S01. In the present invention, the bottom outlet of the liquid-liquid separator S01 is connected to a catalyst concentration tank V05, and the outlet of the catalyst concentration tank V05 is connected to the catalyst inlet of the synthesis reactor R01.

[0055] The device provided by the present invention also includes a distillation tower whose feed port is connected to the top discharge port of the liquid-liquid separator S01. In the present invention, the distillation tower preferably includes a first distillation tower T01, a second distillation tower T02, and a third distillation tower T03 connected in sequence. In the present invention, the feed port of the first distillation tower T01 is connected to the organic phase outlet of the liquid-liquid separator S01, and the top discharge port of the first distillation tower T01 is connected to the feed port of the synthesis reactor R01 via a second delivery pump P02. In the present invention, the feed port of the second distillation tower T02 is connected to the bottom discharge port of the first distillation tower T01. In the present invention, the feed port of the third distillation tower T03 is connected to the bottom discharge port of the second distillation tower T02.

[0056] The following combination Figure 1 The continuous preparation method of 5-methyl-3-hexen-2-one is described in detail. The present invention delivers acetone and isobutyraldehyde to a proportioning tank V04, and continuously introduces them into a reactor R01 with a catalyst for aldol condensation reaction to obtain a reaction liquid containing 5-methyl-3-hexen-2-one. A first delivery pump P01 delivers the reaction liquid containing 5-methyl-3-hexen-2-one to a liquid-liquid separator S01 for liquid-liquid separation, thereby obtaining an aqueous phase and an organic phase, respectively. The aqueous phase is delivered to a catalyst concentration tank V05 for concentration, and the recovered catalyst is delivered to a catalyst preparation tank V01 for reuse. The method comprises the following steps: conveying the organic phase to a first distillation tower T01 for a first distillation to obtain a first distillate and a recovered raw gas; conveying the recovered raw gas to a proportioning tank V04 via a second delivery pump P02 and reused in the aldol condensation reaction; conveying the first distillate to a second distillation tower T02 for a second distillation to obtain a second distillate; conveying the second distillate to a third distillation tower T03 for a third distillation, and liquefying the obtained gas components to obtain 5-methyl-3-hexen-2-one.

[0057] The device provided by the present invention is used to prepare 5-methyl-3-hexen-2-one, which overcomes many limitations of batch production in kettles and achieves the goal of efficient, stable and safe production of 5-methyl-3-hexen-2-one. The present invention uses acetone and isobutyraldehyde as raw materials, which are mixed with a catalyst and then enter a synthesis kettle. The synthesis kettle is heated to a set temperature by steam to trigger the reaction, and the pressure in the kettle first increases and then decreases. After a certain period of reaction, the feeding and discharging are carried out synchronously, and the product flows through a delivery pump into a separator, where the aqueous phase (catalyst aqueous solution) and the organic phase are efficiently separated, thereby realizing the recycling of the catalyst. The separated organic phase enters a distillation tower in turn, and is separated from low to high according to the boiling point, and finally a high-purity 5-methyl-3-hexen-2-one product is obtained, realizing continuous kettle production.

[0058] To further illustrate the present invention, the continuous preparation method and apparatus for 5-methyl-3-hexen-2-one provided by the present invention are described in detail below with reference to the following examples, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] use Figure 1 The device shown continuously prepares 5-methyl-3-hexen-2-one, and the specific steps are as follows:

[0061] Acetone and isobutyraldehyde were transferred to a proportioning tank V04 in a 1:1 molar ratio. The catalyst (ammonium acetate, containing 1 wt% of the total catalyst content) was then continuously introduced into reactor R01 until half of the reactor was filled. The reactor was then heated to 60°C, stirred at 80 rpm, and held for 3 hours. During the reaction, the pressure within the reactor increased and then decreased (by 0.1 to 0.3 MPa). Subsequently, the feed and discharge ports of reactor R01 were simultaneously opened, and the resulting reaction liquid containing 5-methyl-3-hexen-2-one was transferred to a liquid-liquid separator S01 using a first transfer pump P01 for liquid-liquid separation, yielding an aqueous phase and an organic phase. The aqueous phase was then transferred to a catalyst concentration tank V05 for concentration, and the recovered catalyst was transferred to a catalyst preparation tank V01 for reuse in the aldol condensation reaction.

[0062] The organic phase is transferred to the first distillation tower T01 for primary distillation, yielding a primary distillate and a recovered feed gas. The recovered feed gas is transferred to the proportioning tank V04 via the second transfer pump P02 and reused in the aldol condensation reaction. The primary distillate is transferred to the second distillation tower T02 for secondary distillation, yielding a secondary distillate. The secondary distillate is transferred to the third distillation tower T03 for third distillation, and the resulting gaseous components are liquefied to yield 5-methyl-3-hexen-2-one. The top temperature of the first distillation tower T01 is approximately 56-70°C, the bottom temperature is 80-100°C, and the operating pressure is 0.1-0.15 MPa. The top temperature of the second distillation tower T02 is 50-80°C, the bottom temperature is 100-130°C, and the operating pressure is 0.1-0.15 MPa. The top temperature of the third distillation tower T03 is 120-140°C, the bottom temperature is 150-180°C, and the operating pressure is 0.1-0.15 MPa. In this example, the conversion rate of isobutyraldehyde is 73%, the yield of 5-methyl-3-hexen-2-one is 49.4%, the purity is 45.8%, and the selectivity is 67.7%.

[0063] Examples 2 to 7

[0064] 5-Methyl-3-hexen-2-one was prepared according to Example 1. The preparation conditions are shown in Table 1. Other preparation conditions are the same as those in Example 1. The reaction results are shown in Table 1. Figure 2 and Table 1.

[0065] Table 1 Reaction conditions of Examples 1 to 7

[0066]

[0067] By comparing Examples 1 to 3, it can be seen that the appropriate temperature in Example 2 provides the highest conversion rate and yield, indicating that for this reaction, the higher the temperature, the better. By comparing Examples 1 to 3, it can be seen that the combination of moderate temperature and fast stirring rate has the best effect, while the effects of too high temperature (Example 3) and lower temperature (Example 1) are slightly worse. An appropriate molar ratio helps to improve the conversion rate and yield of the reaction. A higher molar ratio can increase the concentration of the reactants and promote the reaction, but if the molar ratio is too high, it may lead to the formation of by-products, thereby affecting the selectivity of the reaction and the purity of the product. In addition, too high a temperature can easily trigger side reactions, leading to the formation of impurities, thereby reducing the selectivity and purity of the product. Therefore, the molar ratio and temperature should be kept within an appropriate range to optimize the reaction effect and ensure the quality of the product.

[0068] As the molar ratio of isobutyraldehyde to acetone increases, the conversion of isobutyraldehyde significantly improves. For example, when the molar ratio increases from 1.2:1 to 1.6:1, the conversion of isobutyraldehyde increases from 74.2% to 88.2%. However, the product selectivity and the yield of 5-methyl-3-hexen-2-one both show a downward trend. For example, at 1.2:1, the product selectivity is 65.3% and the yield is 48.5%, while at 1.6:1, the product selectivity and yield drop to 62.1% and 60.6%, respectively. This indicates that while increasing the molar ratio can promote the conversion of isobutyraldehyde, it may trigger side reactions, resulting in reduced selectivity for the target product. Therefore, balancing the conversion rate and the yield of the target product, the optimal isobutyraldehyde to acetone molar ratio was determined to be 1.4:1.

[0069] As the reaction time increases, the isobutyraldehyde conversion rate, product selectivity, and yield of 5-methyl-3-hexen-2-one all improve. For example, when the reaction time increases from 3 hours to 4 hours, the isobutyraldehyde conversion rate rises from 74.2% to 88.2%, the product selectivity increases from 50.1% to 62.1%, and the yield of the target product also increases from 48.5% to 60.6%. This shows that extending the reaction time can make the reaction more complete, promote the formation of the target product, and improve the overall yield. Therefore, when optimizing process parameters, it is necessary to comprehensively consider the impact of reaction time on reaction results to achieve more efficient continuous production.

[0070] In summary, the continuous preparation method and apparatus for 5-methyl-3-hexen-2-one provided by the present invention overcome the limitations of existing processes by optimizing reaction conditions, catalytic system, and apparatus design, achieve stable, controllable, efficient, and continuous production of the target product, improve overall economic efficiency, and contribute to promoting the widespread application of 5-methyl-3-hexen-2-one in the fields of fine chemicals and high-end materials.

[0071] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A continuous preparation method of 5-methyl-3-hexen-2-one, characterized in that: The following steps are involved: Continuously introducing acetone, isobutyraldehyde and a catalyst into the mixture to carry out an aldol condensation reaction to obtain a reaction solution containing 5-methyl-3-hexen-2-one; the aldol condensation reaction is carried out at a temperature of 50 to 180° C.; the aldol condensation reaction is carried out under stirring at a stirring speed of 50 to 200 r / min; The reaction liquid containing 5-methyl-3-hexen-2-one is continuously discharged and subjected to liquid-liquid separation to obtain an aqueous phase and an organic phase respectively; the catalyst in the aqueous phase is recovered and reused in the aldol condensation reaction; The organic phase is distilled to obtain a recovered raw material and 5-methyl-3-hexene-2-one respectively; the recovered raw material is used for the aldol condensation reaction.

2. The continuous preparation method according to claim 1, wherein The molar ratio of the isobutyraldehyde to acetone is 0.5-1.6:

1.

3. The continuous preparation method according to claim 1, characterized in that The catalyst includes a nitrogen-containing compound.

4. The continuous preparation method according to any one of claims 1 to 3, characterized in that: The ratio of the total mass of the acetone and isobutyraldehyde to the mass of the catalyst is 97-99:1-3.

5. The continuous preparation method according to any one of claims 1 to 3, characterized in that: The aldol condensation reaction is carried out under a pressure of 0.1 to 0.3 MPa and for a time of 1 to 4 hours.

6. The continuous preparation method according to claim 1, characterized in that The rectification comprises: The organic phase is subjected to a first rectification to obtain a first distillate and a recovered raw gas; the recovered raw gas is reused in the aldol condensation reaction step; subjecting the first distillate to a second distillation to obtain a second distillate; The second distillate is subjected to a third distillation to obtain 5-methyl-3-hexen-2-one.

7. The continuous preparation method according to claim 6, characterized in that The first distillation is carried out in a first distillation tower, the top temperature of the first distillation tower is 56-70°C, and the bottom temperature of the tower is 80-100°C; The second distillation is carried out in a second distillation tower, the top temperature of the second distillation tower is 50-80°C, and the bottom temperature of the tower is 100-130°C; The third distillation is carried out in a third distillation tower, the tower top temperature of the third distillation tower is 120-140°C, and the tower top temperature is 150-180°C.

8. The device used in the continuous preparation method according to any one of claims 1 to 7, characterized in that: The invention comprises a synthesis reactor (R01), wherein a stirring device is provided in the synthesis reactor (R01); A liquid-liquid separator (S01) whose feed port is connected to the discharge port of the synthesis reactor (R01); the bottom discharge port of the liquid-liquid separator (S01) is connected to a catalyst concentration tank (V05), and the discharge port of the catalyst concentration tank (V05) is connected to the feed port of the synthesis reactor (R01); A distillation tower having a feed inlet connected to the organic phase outlet of the liquid-liquid separator (S01).

9. The device according to claim 8, characterized in that The distillation tower comprises a first distillation tower (T01), a second distillation tower (T02) and a third distillation tower (T03) which are connected in sequence; The feed port of the first distillation tower (T01) is connected to the organic phase outlet of the liquid-liquid separator (S01), and the top discharge port of the first distillation tower (T01) is connected to the feed port of the synthesis reactor (R01) through a second delivery pump (P02).

10. The device according to claim 8 or 9, characterized in that The device further comprises a catalyst preparation tank (V01), an acetone storage tank (V02), an isobutyraldehyde storage tank (V03) and a proportioning tank (V04); the discharge ports of the catalyst preparation tank (V01) and the proportioning tank (V04) are communicated with the feed port of the synthesis reactor (R01); the discharge ports of the acetone storage tank (V02) and the isobutyraldehyde storage tank (V03) are communicated with the feed port of the proportioning tank (V04); A first delivery pump (P01) is also provided on the pipeline connecting the synthesis reactor (R01) and the liquid-liquid separator (S01).

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