A catalyst for cyclopropyl methyl ketone condensation reaction and a preparation method of 1,3-bicyclopropyl-2-buten-1-one

Abstract

The application discloses a catalyst for cyclopropyl methyl ketone condensation reaction and a preparation method of 1,3-bicyclopropyl-2-butene-1-ketone. The catalyst is a supported catalyst. The activity of the catalyst is improved through cooperation of a porous carrier and an active component. The catalyst can catalyze self-hydroxy aldehyde condensation reaction of cyclopropyl methyl ketone. The method comprises the following steps: separately injecting cyclopropyl methyl ketone and the catalyst into a fixed bed reactor, controlling mass space velocity of the cyclopropyl methyl ketone, condensing and collecting, post-treating the product and obtaining 1,3-bicyclopropyl-2-butene-1-ketone. The application adopts the fixed bed reactor to make the cyclopropyl methyl ketone flow in one direction in the reaction tube and contact the catalyst, promotes the reaction equilibrium to move to the right and reduces the possibility of generating by-products. The progress of the reaction process is controlled by adjusting the mass space velocity of the cyclopropyl methyl ketone, so that the cyclopropyl methyl ketone fully contacts the catalyst and reacts, and the yield and selectivity of the product are improved as a whole.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic synthesis, and particularly relates to a catalyst for a cyclopropyl methyl ketone condensation reaction and a preparation method of 1,3-bicyclopropyl-2-buten-1-one. BACKGROUND

[0002] 1,3-bicyclopropyl-2-buten-1-one is a product obtained from cyclopropyl methyl ketone via a self-aldol condensation reaction and elimination of one molecule of water. The substance has a special aroma and can be used as a perfume or an additive. It can also be used for the synthesis of flavonoid substances and serves as an important pharmaceutical intermediate. Due to the cyclopropane high-energy structure, it can also be used for the preparation of liquid hydrocarbon fuels to improve key performance such as calorific value. Therefore, 1,3-bicyclopropyl-2-buten-1-one has a relatively wide range of applications.

[0003] Cyclopropyl methyl ketone has special stability. The commonly used aldol condensation reaction conditions, such as alkali catalysts such as sodium carbonate, calcium hydroxide, and sodium methoxide, have insufficient activity and cannot catalyze the reaction. The self-aldol condensation reaction of ketones is seriously biased to the left side of the balance, which means that a batch reactor cannot drive the balance to move to the right.

[0004] In the prior art, Russian researchers have used inexpensive potassium hydroxide as a catalyst to prepare 1,3-bicyclopropyl-2-buten-1-one by high-temperature distillation, but the yield is only 20%, the selectivity is less than 40%, and the material utilization efficiency is not high. Some use calcium hydride to catalyze the reaction, and the yield can reach 50%, but calcium hydride loses its effectiveness when it absorbs water, and the exothermic reaction produces hydrogen gas, which poses a safety hazard. Some use tert-butyl aluminum as a high-efficiency condensing agent to prepare 1,3-bicyclopropyl-2-buten-1-one, which can achieve a yield of 74% and a selectivity of >99%. However, tert-butyl aluminum is very expensive, about 150,000 yuan / kg, so this method is not suitable for large-scale application.

[0005] Therefore, the present application is proposed. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the shortcomings of the prior art and provide a catalyst for a cyclopropyl methyl ketone condensation reaction. The catalyst is a supported catalyst. Through the cooperation of the porous support and the active component, the number of catalytic sites is increased. The catalyst has high activity, is not prone to agglomeration and deactivation, has low cost, can catalyze the self-aldol condensation reaction of cyclopropyl methyl ketone, effectively improves the yield and selectivity of the reaction product, is easy to separate after the reaction, has little pollution, has low requirements for the device, and lays a foundation for large-scale industrial production in the future.

[0007] To solve the above technical problems, the basic idea of the technical solution of the present application is as follows:

[0008] A catalyst for the condensation reaction of cyclopropyl methyl ketone, said catalyst being a supported catalyst comprising a support and an active component supported on the support;

[0009] The carrier has a porous structure and is selected from one or more combinations of Al2O3, MgO, SiO2, TiO2, and ZrO2;

[0010] The active component is selected from one or more combinations of Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, and Ce.

[0011] Furthermore, the active component is selected from one or more combinations of Mg, Ca, Sr, Ba, Sc, Y, La, and Ce;

[0012] Preferably, the active component is selected from one or more combinations of Mg, Ca, Sc, and Y;

[0013] More preferably, the active component is Sc.

[0014] In the above schemes, the active components, when loaded onto the support, exist in the form of oxides, all possessing certain acidity and basicity. These properties respectively activate the ketone carbonyl group and deprotonate it, effectively promoting the aldol condensation reaction. Among these, when the active component is Sc, the acidity and basicity of its oxide are optimally matched, and the basicity is not too strong, preventing further reaction between the product and cyclopropylmethyl ketone, thus improving the product yield and selectivity.

[0015] Furthermore, the active component accounts for 0.5% to 12% of the mass of the carrier, preferably 5% to 10%, and more preferably 5%.

[0016] In the above scheme, within the aforementioned limits, the reaction yield increases with the increase of the loading of the active component. However, after the loading reaches 5%, further increasing the loading of the active component has no significant effect on improving the reaction yield. Considering the relatively high price of metal nitrates, under the premise of ensuring high product yield and selectivity without increasing costs, an excessively high loading is not used. Instead, the active component is selected to account for 5% of the mass of the support.

[0017] Furthermore, the support is selected from one or more combinations of Al2O3, MgO, and SiO2;

[0018] Preferably, the carrier is Al2O3.

[0019] In the above schemes, the Al2O3, MgO, SiO2, TiO2, and ZrO2 specified in this invention, as porous supports, can effectively increase the specific surface area, thereby increasing the loading of active components and making them uniformly dispersed. This increases the number of catalytic sites, significantly improves catalytic performance, and the prepared catalyst is not prone to agglomeration or deactivation, has a long lifespan, and possesses suitable acidity and basicity to activate ketone carbonyl groups and deprotonate them, respectively, effectively promoting aldol condensation reactions. Among these, when the support is Al2O3, the acidity and basicity of Al2O3 are most appropriately matched, which is more conducive to the deprotonation reaction of the raw materials and can play a better role in activating ketone carbonyl groups, significantly improving the yield and selectivity of the product.

[0020] Preferably, the catalyst is a spherical catalyst.

[0021] In the above scheme, the preparation method of the spherical catalyst is the equal volume impregnation method, that is, the corresponding metal nitrate aqueous solution is prepared according to the percentage of the active component to the mass of the support, the spherical support is added to the metal nitrate aqueous solution at one time under vigorous stirring, the mixture is returned to room temperature, vacuum dried, and then calcined in a tube furnace at a certain heating rate in an argon atmosphere to a specified temperature for a period of time. After cooling to room temperature, the spherical catalyst is obtained.

[0022] The catalyst is simple to prepare, can be mass-produced for industrial scale-up, has reasonable acid and base strength, is easy to regenerate by air calcination, does not easily accumulate carbon, and has good recyclability.

[0023] This invention employs a supported solid base catalyst for catalytic reaction, which not only catalyzes the self-aldol condensation reaction of cyclopropyl methyl ketone, effectively improving the yield and selectivity of the reaction product, but also, through the combination of a porous support and active components, increases the catalytic sites compared to traditional free inorganic solid base catalysts, making it less prone to catalyst agglomeration and deactivation. The catalyst is easy to separate after the reaction, produces less pollution, and has low equipment requirements, laying the foundation for future large-scale industrial production.

[0024] A method for preparing 1,3-bicyclopropyl-2-buten-1-one, using a catalyst for the condensation reaction of cyclopropyl methyl ketones as described above, the method comprising:

[0025] 1,3-Bicyclopropyl-2-buten-1-one was prepared by a self-aldol condensation reaction of cyclopropylmethyl ketone under the catalysis of a catalyst, wherein the reaction temperature of the self-aldol condensation reaction was 200℃~320℃.

[0026] Preferably, the reaction temperature is 260℃~280℃.

[0027] In the above scheme, at the specified temperature, cyclopropyl methyl ketone can undergo an aldol condensation reaction under the catalysis of the catalyst. The high temperature can prevent the water generated by the aldol condensation reaction from accumulating on the catalyst surface and inhibiting the reaction. However, if the reaction temperature is too high, some cyclopropyl methyl ketone will undergo an isomerization reaction to generate 2-methyl-4,5-dihydrofuran, reducing the selectivity of the product. If the reaction temperature is too low, the reaction will be too slow, reducing the production efficiency.

[0028] Furthermore, the reaction time for the aldol condensation reaction is 0.15 h to 4 h;

[0029] Preferably, the reaction time is 0.4h to 2h, and more preferably 1h.

[0030] In the above scheme, the reaction time refers to the contact time between a unit mass of cyclopropyl methyl ketone and the catalyst. Within the defined reaction time, cyclopropyl methyl ketone and the catalyst can be fully contacted, allowing the catalytic reaction to proceed without over-reaction, ensuring the utilization rate of raw materials and the yield of products, and improving product selectivity. If the reaction time is too short, the raw materials cannot be converted in time, resulting in a low yield; if the reaction time is too long, by-products are easily generated, reducing product selectivity and increasing energy consumption and cost.

[0031] Furthermore, the mass of the catalyst is 1% to 40% of the mass of cyclopropyl methyl ketone;

[0032] Preferably, the mass of the catalyst is 6% to 10% of the mass of cyclopropyl methyl ketone, more preferably 6%.

[0033] In the above schemes, when the mass of the catalyst and the mass of cyclopropyl methyl ketone are within the above-defined range, the catalyst has a good catalytic effect on cyclopropyl methyl ketone, which can effectively catalyze and induce the self-aldol condensation reaction of cyclopropyl methyl ketone, reduce the generation of by-products, facilitate post-processing, and achieve high production efficiency. However, if the amount of catalyst used is large, its adsorption of raw materials will increase, resulting in deep reactions, generating by-products, reducing selectivity, and making post-reaction processing difficult. If the amount of catalyst used is small, the reaction time will be prolonged, reducing production efficiency.

[0034] Furthermore, the reaction pressure is 0.1MPa to 2MPa, preferably 0.1MPa to 1.2MPa. If the pressure is too high, the pressure-bearing requirements of the reactor inner wall material will be further increased, which may easily lead to safety hazards.

[0035] Furthermore, the purity of the cyclopropyl methyl ketone is not less than 98.5%.

[0036] In the above scheme, the purity of the raw material cyclopropyl methyl ketone is relatively high, which is conducive to the smooth progress of the reaction and prevents the presence of impurities such as 2-methylfuran and acetyl-n-propanol in the raw material with low purity, which can easily cause catalyst coking and affect catalytic efficiency; moreover, the raw material cyclopropyl methyl ketone is an industrial raw material and is easy to purchase.

[0037] Furthermore, the method includes the following steps:

[0038] The catalyst was loaded into the reaction tube of the fixed-bed reactor, the temperature was adjusted to the reaction temperature, and after the reaction tube was kept at a constant temperature, cyclopropyl methyl ketone was introduced into the reaction tube and the mass hourly space velocity of cyclopropyl methyl ketone was controlled. The product was collected by condensation and post-processing to obtain 1,3-biscyclopropyl-2-buten-1-one.

[0039] In the above scheme, by using a gas-solid phase fixed-bed reactor, the raw material cyclopropyl methyl ketone flows unidirectionally in the fixed-bed reaction tube and contacts the catalyst. The product 1,3-bicyclopropyl-2-buten-1-one is generated and flows out immediately, thereby controlling the contact reaction time between the raw material and the catalyst and pushing the reaction equilibrium to the right, reducing the possibility of the product continuing to participate in the reaction and generating by-products.

[0040] Specifically, cyclopropyl methyl ketone can be first injected into the feed tank of a fixed-bed reactor, purged with inert gas, and kept at a constant temperature. Then, the catalyst is loaded into the reaction tube of the fixed-bed reactor, purged with inert gas, and kept at a constant temperature to the reaction temperature. After the reaction tube is kept at a constant temperature, inert gas is introduced, and the gas flow meter is turned on and adjusted to control the mass hourly space velocity of cyclopropyl methyl ketone. The product is then condensed and collected. The product is post-processed to obtain 1,3-biscyclopropyl-2-buten-1-one.

[0041] The cyclopropyl methyl ketone is highly flammable. During the reaction, an inert gas is used for protection, preferably N2. At the same time, an inert gas is introduced as a carrier gas to drive the cyclopropyl methyl ketone through the catalyst to react. The inert gas is a high-purity gas and will not affect the occurrence of the reaction or the formation of products.

[0042] It should be noted that cyclopropyl methyl ketone can also be injected first into a storage tank outside the fixed-bed reactor. Then, a feedstock flow pipeline can be connected between the storage tank and the fixed-bed reaction tube. Before the reaction, the storage tank and feedstock flow pipeline should be treated with inert gas purging, temperature insulation, and pressure control to ensure that the cyclopropyl methyl ketone can smoothly enter the reaction tube and contact the catalyst for reaction. Simultaneously, feedstock can be transported using methods other than carrier gas, allowing for reasonable and controllable contact time between the feedstock and catalyst, ensuring that the product flows out immediately upon formation.

[0043] Furthermore, the mass hourly space velocity (MSV) of the cyclopropyl methyl ketone is 0.1 h⁻¹. -1 ~2.5h -1 ;

[0044] Preferably, the mass hourly space velocity (MSV) of the cyclopropyl methyl ketone is 0.4 h⁻¹. -1 ~1h -1 Preferably 0.4h -1 .

[0045] In the above scheme, the mass hourly space velocity (MHSV) refers to the mass of reactant passing through a unit volume of catalyst per unit time. The flow rate and velocity of the carrier gas are controlled by a gas flow meter, thereby adjusting the MHSV of cyclopropyl methyl ketone (CMK) to regulate the contact time between CMK and the catalyst. This ensures sufficient contact between CMK and the catalyst, improving feedstock utilization and product yield. If the MHSV of CMK is too high, insufficient contact between CMK and the catalyst will result in low feedstock utilization and product yield. If the MHSV of CMK is too low, the contact time between CMK and the catalyst will be too long, leading to excessive adsorption, deep reaction, and the formation of polymers that rapidly deposit carbon, affecting the catalytic performance of the catalyst. Simultaneously, the product 1,3-biscyclopropyl-2-buten-1-one will continue to undergo a Michael addition reaction with CMK, reducing product selectivity.

[0046] Furthermore, the condensation temperature during product collection is -30℃ to 20℃.

[0047] In the above schemes, a suitable condensation temperature is beneficial for product collection, improving product yield and selectivity. If the temperature is too low, a larger condensation power is required, increasing energy consumption and cost; if the temperature is too high, unreacted raw materials will be partially lost due to incomplete liquefaction, reducing the recovery rate of raw materials.

[0048] Furthermore, the post-processing includes: adding a desiccant to the collected liquid, filtering and collecting the filtrate, distilling under reduced pressure, and collecting the fraction at 10 Pa and 120 °C, which is 1,3-bicyclopropyl-2-buten-1-one.

[0049] In the above scheme, the post-processing includes drying, filtration, and purification. Specifically, the desiccant is added to the collected liquid in batches and stirred until the newly added desiccant no longer absorbs water or clumps. The filtrate is then collected by filtration and vacuum distillation. The fraction collected at 0.1 MPa and 114 °C is the unreacted cyclopropylmethyl ketone. The fraction collected at 10 Pa and 120 °C is the 1,3-bicyclopropyl-2-buten-1-one.

[0050] The method of the present invention yields 1,3-bicyclopropyl-2-buten-1-one with a yield of up to 94% and a selectivity of up to 99%, improving atom economy and minimizing environmental pollution.

[0051] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0052] 1. This invention uses a supported solid base catalyst for catalytic reaction, which can not only catalyze the self-aldol condensation reaction of cyclopropyl methyl ketone, effectively improving the yield and selectivity of the reaction product, but also, through the combination of porous support and active components, increases the catalytic sites compared with traditional free inorganic solid base catalysts, making it less prone to catalyst agglomeration, less prone to catalyst deactivation, easy to separate after the reaction, less polluting, and with low requirements for equipment.

[0053] 2. This invention employs a gas-solid phase fixed-bed reactor, which allows the raw material cyclopropyl methyl ketone to flow unidirectionally in the fixed-bed reaction tube and contact the catalyst. The product 1,3-biscyclopropyl-2-buten-1-one is generated and flows out immediately, thereby shifting the reaction equilibrium to the right, reducing the possibility of the product continuing to participate in the reaction and generating byproducts, and improving the product yield and selectivity.

[0054] 3. This invention controls the reaction process by adjusting the mass hourly space velocity of cyclopropyl methyl ketone, ensuring sufficient contact between cyclopropyl methyl ketone and the catalyst without excessive adsorption leading to deep reactions and polymer formation, thereby improving the overall yield and selectivity of the product.

[0055] 4. The gas-solid phase fixed-bed reactor used in this invention improves the product yield and selectivity, simplifies the operation process, facilitates process scale-up, and has low cost, laying the foundation for subsequent large-scale production of products.

[0056] The specific embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Attached Figure Description

[0057] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0058] Figure 1 This is the 1H NMR spectrum (600MHz, CDCl3) of 1,3-bicyclopropyl-2-buten-1-one in this invention.

[0059] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0060] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below with reference to some embodiments. Those skilled in the art will understand that the following embodiments are only used to explain the technical principles of this invention and are not intended to limit the scope of protection of this invention. For example, although this application describes the steps of the method of this invention in a specific order, these orders are not restrictive. Those skilled in the art can perform the steps in different orders without departing from the basic principles of this invention.

[0061] It should be noted that:

[0062] Methods for calculating product yield and selectivity:

[0063] Yield and selectivity were determined by gas chromatography (flame ionization detector), and the peak areas of the raw materials, main products and by-products were normalized.

[0064] Product yield = main product peak area / total peak area;

[0065] Raw material conversion rate = 1 - raw material peak area / total peak area;

[0066] Product selectivity = Product yield / Raw material conversion rate.

[0067] Catalyst preparation:

[0068] Activation of the support: Weigh out Al2O3 support (40-mesh spherical, with a specific surface area of ​​approximately 180 m²). 2 / g, with an average pore size of approximately 50nm) 1.0kg, is placed in an alumina crucible, placed in a muffle furnace, heated to 400℃ at 30℃ / min in a dry air atmosphere and held for 1h, cooled to room temperature, and then taken out for use.

[0069] Impregnation: Weigh 376.7 g of Sc(NO3)3·6H2O, dissolve it in 400 mL of deionized water with vigorous stirring, and after the solution returns to room temperature, immediately add it all to a beaker containing Al2O3 support. Sonicate for 20 min to ensure the impregnation solution is evenly distributed on the surface of the support. Dry at 120℃ for 1 h to evaporate the moisture.

[0070] Calcination: Take out the dried catalyst precursor, put it into a corundum crucible, place it in a muffle furnace, heat it to 600℃ at 10℃ / min in air atmosphere and hold it for 4h, cool it to room temperature, take out the sample and weigh it to a total of 1040.5g, which is the spherical catalyst of 5%Sc@Al2O3.

[0071] Example 1

[0072] (1) 1.5 kg of raw material cyclopropyl methyl ketone was injected into the raw material tank of the fixed bed reactor, N2 was replaced 3 times, and the temperature was kept at 114℃.

[0073] (2) 90.0 g of the 5% Sc@Al2O3 spherical catalyst prepared above was loaded into the fixed bed reaction tube, and after being replaced with N2 three times, the temperature was kept at 280℃.

[0074] (3) After the reaction tube is kept at a constant temperature, high-purity N2 carrier gas is introduced, and the gas flow meter is turned on and adjusted to control the mass hourly space velocity (MSV) of cyclopropyl methyl ketone to be 0.4 h⁻¹. -1 To maintain the contact time between a unit mass of cyclopropylmethyl ketone and the catalyst for 1 hour, the product within 6 hours was collected by condensation.

[0075] (4) After the reaction is complete, the collected liquid is dried with anhydrous magnesium sulfate and filtered to remove insoluble matter; the fraction collected at 0.1 MPa and 114 °C is the unreacted cyclopropylmethyl ketone; the fraction collected at 10 Pa and 120 °C is 1,3-bicyclopropyl-2-buten-1-one.

[0076] Comparative Example 1

[0077] Based on Example 1, the spherical catalyst was replaced with potassium hydroxide, while other preparation conditions remained unchanged.

[0078] Comparative Example 2

[0079] Based on Example 1, the spherical catalyst was replaced with a macroporous basic resin catalyst, while other preparation conditions remained unchanged.

[0080] Comparative Example 3

[0081] 1.5 kg of cyclopropyl methyl ketone was added to a batch reactor, along with 90.0 g of spherical catalyst, wherein the active component was Sc and the support was Al2O3, with the active component accounting for 5% of the mass of the support. The stirring speed was 120 rpm, the reaction temperature was 280℃, the pressure was 0.3 MPa, and the reaction time was 6 h. The product was obtained after post-treatment.

[0082] Experimental Example 1

[0083] This experiment tested the yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one in Example 1, Comparative Examples 1 to 3. The test results are shown in Table 1.

[0084] Table 1

[0085]

[0086] As shown in Table 1, Example 1 was prepared according to the method of the present invention. A gas-solid phase fixed-bed reactor was used to allow the raw material cyclopropyl methyl ketone to flow unidirectionally in the fixed-bed reaction tube and contact the catalyst. The product 1,3-biscyclopropyl-2-buten-1-one was generated and flowed out immediately, thereby shifting the reaction equilibrium to the right, reducing the possibility of the product continuing to participate in the reaction and generating by-products, and improving the product yield and selectivity. The reaction progress was controlled by adjusting the mass hourly space velocity of cyclopropyl methyl ketone, so that cyclopropyl methyl ketone could be fully contacted with the catalyst, but without excessive adsorption and deep reaction to generate polymers, thus improving the overall product yield and selectivity. By using a supported solid base catalyst for catalytic reaction, not only can the self-aldol condensation reaction of cyclopropyl methyl ketone be catalyzed, effectively improving the yield and selectivity of the reaction product, but also, through the combination of porous support and active components, compared with traditional free inorganic solid base catalysts, the number of catalytic sites is increased, catalyst agglomeration is not easy to occur, catalyst deactivation is not easy, catalyst effect is good, and the catalyst life is as long as 1500h at high temperature, which can be reused without frequent replacement, effectively reducing costs. The combination of fixed-bed reactor, mass hourly space velocity, and catalyst type achieved a synergistic effect, which improved the overall yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one.

[0087] Although a fixed-bed reactor was also used in Comparative Example 1, the catalyst used was potassium hydroxide, which had insufficient catalyst activity and poor catalytic effect, resulting in low yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one.

[0088] Similarly, although a fixed-bed reactor was also used in Comparative Example 2, the catalyst used was a macroporous basic resin catalyst. Macroporous basic resins deactivate quickly at high temperatures, with a lifespan of only about 10 minutes. Therefore, the reaction time between the raw materials and the catalyst was very short, resulting in a very low product yield. Furthermore, the need to frequently replace the catalyst made the operation cumbersome and significantly increased the cost, making it unsuitable for large-scale industrial production.

[0089] In Comparative Example 3, a batch reactor was used to prepare 1,3-bicyclopropyl-2-buten-1-one. Due to the severe left-hand bias in the self-aldol condensation reaction equilibrium of the ketone, and the induction reactor's inability to shift the equilibrium to the right, the generated product could not be discharged in time, resulting in over-reaction and low yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one.

[0090] Experiment Example 2

[0091] As described in Example 1, to investigate the effect of the catalyst active component on the aldol condensation of cyclopropylmethyl ketone, only the catalyst active component was changed while other conditions remained the same, resulting in Examples 2 to 17, as shown in the table below:

[0092] Table 2

[0093]

[0094] As shown in Table 2, when the support is constant (Al2O3) and the active components are Rb, Cs, Mg, Ca, Sr, Ba, Sc, Y, La, and Ce, all of these components can catalyze the aldol condensation reaction of cyclopropyl methyl ketone, with yields of 1,3-bicyclopropyl-2-buten-1-one exceeding 20% ​​and selectivity exceeding 70%. When the active components are Mg, Ca, Sr, Ba, Sc, Y, La, and Ce, the selectivity for 1,3-bicyclopropyl-2-buten-1-one exceeds 90%. When the active components are Mg, Ca, Sc, and Y, the yields of 1,3-bicyclopropyl-2-buten-1-one exceed 50% and the selectivity exceeds 95%. In particular, when the active component is Sc, the yield of 1,3-bicyclopropyl-2-buten-1-one reaches as high as 94%, and the selectivity reaches as high as 99%. This is because the oxide of Sc has both suitable basicity and acidity, which respectively play the roles of deprotonation and activation of ketone carbonyl group, resulting in the highest product yield; and the basicity is not too strong, so as not to cause the product to continue to react with cyclopropylmethyl ketone, resulting in high selectivity.

[0095] However, when the active components are Li, Na, K, V, Nb, Fe, Zn, etc., the deprotonation and activation of the ketone carbonyl group are not obvious due to the unsuitable acidity or basicity of the oxides. Therefore, although it can catalyze the aldol condensation reaction of cyclopropyl methyl ketone, the yield of 1,3-bicyclopropyl-2-buten-1-one is very low and the selectivity is also low.

[0096] Experimental Example 3

[0097] As described in Example 1, to investigate the effect of the catalyst support on the self-aldol condensation of cyclopropyl methyl ketone, only the catalyst support was changed while other conditions remained the same, resulting in Examples 18 to 21, as shown in the table below:

[0098] Table 3

[0099]

[0100] As shown in Table 3, when the active component Sc remains constant, and the catalyst support is Al2O3, MgO, SiO2, TiO2, or ZrO2, the yield of 1,3-bicyclopropyl-2-buten-1-one is above 20%, and the selectivity is above 70%. When the catalyst support is Al2O3, MgO, or SiO2, the selectivity of 1,3-bicyclopropyl-2-buten-1-one is above 95%, especially when the catalyst support is Al2O3, the yield of 1,3-bicyclopropyl-2-buten-1-one reaches as high as 94%, and the selectivity reaches as high as 99%. This is because, compared to Al2O3, although MgO support is strongly basic, it is not easy to form, and the prepared catalyst is prone to agglomeration, resulting in reduced catalytic activity and thus lower product yield. Meanwhile, SiO2, TiO2, and ZrO2 supports are more acidic, which is not conducive to the deprotonation reaction of the raw materials, thus reducing the product yield.

[0101] Sc is basic and Al2O3 is acidic. The combination of the two has a synergistic effect, and the prepared catalyst has more suitable acidity and basicity. It can play a good role in activating the carbonyl group of ketone and deprotonating it, promoting the aldol condensation reaction and improving the yield and selectivity of the product.

[0102] Experiment Example 4

[0103] As described in Example 1, to investigate the effect of the mass percentage of the active component in the carrier on the self-aldol condensation effect of cyclopropylmethyl ketone, only the mass percentage of the active component in the carrier was changed, while other conditions remained the same, resulting in Examples 22 to 27, as shown in the table below:

[0104] Table 4

[0105]

[0106] As can be seen from the data in Table 4, when the mass percentage of the active component in the support is 0.5-12% as specified in this application, the selectivity for preparing 1,3-bicyclopropyl-2-buten-1-one is 99%, and the yield increases linearly; especially when the mass percentage of the active component in the support is 5-12% as specified in this application, the yield for preparing 1,3-bicyclopropyl-2-buten-1-one is higher than 90%.

[0107] As shown in Table 4, when the active component accounts for 5% of the support mass, the product yield reaches 94% and the selectivity reaches 99%. Further increasing the loading of the active component beyond 10% does not significantly improve the product yield and selectivity. Therefore, a loading of 5%–10% of the support mass is preferred. However, compared to a loading of 5%, increasing the loading has little effect on improving the reaction yield. Furthermore, considering the relatively high price of metal nitrates, to ensure high product yield and selectivity without increasing costs, an excessively high loading is avoided; instead, a loading of 5% of the support mass is chosen.

[0108] If the mass percentage of the active component in the support is too low, as in Example 22, the catalytic activity of the catalyst is insufficient, resulting in a decrease in the catalytic effect and affecting the product yield and production efficiency. On the other hand, if the mass percentage of the active component in the support is too high, the active sites will change from a single layer to multiple layers, making them prone to aggregation. Even if the loading of the active component is increased, it will have little effect on the catalyst activity and will increase the cost.

[0109] Experimental Example 5

[0110] As described in Example 1, to investigate the effect of reaction temperature on the aldol condensation of cyclopropylmethyl ketone, only the reaction temperature was changed while other conditions remained the same, resulting in Examples 28 to 36, as shown in the table below:

[0111] Table 5

[0112]

[0113]

[0114] As can be seen from the data in Table 5, when the reaction temperature is 200–320℃, the yield of 1,3-bicyclopropyl-2-buten-1-one is above 40%, and the selectivity is above 80%. When the reaction temperature is 200–300℃, the selectivity of 1,3-bicyclopropyl-2-buten-1-one is above 90%. In particular, when the reaction temperature is 260–280℃, the yield of 1,3-bicyclopropyl-2-buten-1-one is above 80%, and the selectivity is 99%. Especially when the reaction temperature is 280℃, the yield of 1,3-bicyclopropyl-2-buten-1-one reaches as high as 94%, and the selectivity reaches as high as 99%.

[0115] However, if the reaction temperature is too high, as in Examples 34 to 36, some of the cyclopropyl methyl ketones will undergo isomerization to generate 2-methyl-4,5-dihydrofuran, reducing the selectivity of the reaction; while if the reaction temperature is too low, the reaction will be too slow.

[0116] Experimental Example 6

[0117] Following the preparation process described in Example 1, by changing the percentage of catalyst mass to cyclopropyl methyl ketone mass while keeping other conditions the same, Examples 37 to 41 were obtained, as shown in the table below:

[0118] Table 6

[0119]

[0120] As shown in Table 6, when the mass of the catalyst is 1%–40% of the mass of cyclopropyl methyl ketone, the product yield gradually increases with increasing catalyst mass. However, when the percentage of catalyst mass in cyclopropyl methyl ketone exceeds 10%, increasing catalyst mass has no significant effect on improving product yield; instead, it reduces product selectivity. Therefore, to ensure the desired product is obtained, the preferred catalyst mass percentage is between 6% and 10% of the mass of cyclopropyl methyl ketone. At this range, both product yield and selectivity are greater than 90%. In particular, when the catalyst mass percentage in cyclopropyl methyl ketone is 6%, the prepared product achieves a yield of 94% and a selectivity of 99%.

[0121] If the mass percentage of the catalyst relative to the mass of cyclopropyl methyl ketone is too high, i.e., when the amount of catalyst used is large, its adsorption of the raw materials increases, which will promote deep reactions between the raw materials and / or products, generating by-products, reducing the selectivity for preparing 1,3-biscyclopropyl-2-buten-1-one, and is not conducive to post-reaction processing; if the mass percentage of the catalyst relative to the mass of cyclopropyl methyl ketone is too low, as in Example 37, it will reduce the product yield, prolong the reaction time, and reduce production efficiency.

[0122] Experimental Example 7

[0123] By changing the mass hourly space velocity (MHSV) of cyclopropyl methyl ketone, the contact reaction time between cyclopropyl methyl ketone and the catalyst can be controlled. Following the preparation process described in Example 1, to investigate the effect of MHSV on the self-aldol condensation of cyclopropyl methyl ketone, the MHSV was changed while other conditions remained constant, resulting in Examples 42 to 46, as shown in the table below:

[0124] Table 7

[0125]

[0126] As can be seen from the data in Table 7, when the mass hourly space velocity is 0.1 h⁻¹ -1 ~2.5h -1The selectivity for preparing 1,3-bicyclopropyl-2-buten-1-one gradually increased, with the yield initially increasing and then decreasing, but the yield of the product remained above 60%, and the selectivity remained above 80%; when the mass hourly space velocity (HHSV) was 0.4 h⁻¹. -1 ~1h -1 The selectivity for preparing 1,3-bicyclopropyl-2-buten-1-one was 99%, and the yield was above 80%; especially when the mass hourly space velocity (HHSV) was 0.4 h⁻¹. -1 When preparing 1,3-bicyclopropyl-2-buten-1-one, the yield was as high as 94% and the selectivity was as high as 99%.

[0127] If the mass hourly space velocity (MHSV) of cyclopropyl methyl ketone is too high, as in Example 46, it will lead to insufficient contact between cyclopropyl methyl ketone and the catalyst, resulting in low utilization of raw materials and low product yield. If the MHSV of cyclopropyl methyl ketone is too low, as in Example 42, it will easily cause excessive adsorption of cyclopropyl methyl ketone and the catalyst, resulting in deep reaction, the formation of polymers and rapid coking, which will affect the catalytic performance of the catalyst. At the same time, the product 1,3-biscyclopropyl-2-buten-1-one will continue to undergo Michael addition reaction with cyclopropyl methyl ketone, which will reduce the product yield and selectivity.

[0128] It should be noted that, Figure 1 The image shows the 1H NMR spectrum (600MHz, CDCl3) of 1,3-bicyclopropyl-2-buten-1-one. The peak with a chemical shift of 6.27 ppm corresponds to sp2 CH, i.e., a hydrogen atom directly bonded to a carbon-carbon double bond, confirming that the product is 1,3-bicyclopropyl-2-buten-1-one and that its structure is correct, as shown below:

[0129]

[0130] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing 1,3-bicyclopropyl-2-buten-1-one, characterized in that, The preparation method involves using a catalyst for the condensation reaction of cyclopropyl methyl ketone, wherein cyclopropyl methyl ketone undergoes an aldol condensation reaction under the catalysis of the catalyst to prepare 1,3-biscyclopropyl-2-buten-1-one, and the reaction temperature of the aldol condensation reaction is 200℃~320℃. The specific steps are as follows: a catalyst is loaded into the reaction tube of the fixed-bed reactor, the temperature is adjusted to the reaction temperature, the reaction tube is kept at a constant temperature, cyclopropyl methyl ketone is introduced into the reaction tube and the mass hourly space velocity of cyclopropyl methyl ketone is controlled, the product is collected by condensation, and the product is post-processed to obtain 1,3-biscyclopropyl-2-buten-1-one. The mass hourly space velocity (MSV) of the cyclopropyl methyl ketone is 0.4 h⁻¹. -1 ; The catalyst is a supported catalyst, comprising a support and an active component supported on the support; The carrier has a porous structure and is selected from Al2O3; the active component is Sc.

2. The preparation method according to claim 1, characterized in that, The active component accounts for 0.5% to 12% of the mass of the carrier.

3. The preparation method according to claim 1, characterized in that, The active component accounts for 5% to 10% of the mass of the carrier.

4. The preparation method according to claim 1, characterized in that, The active component accounts for 5% of the mass percentage of the carrier.

5. The preparation method according to any one of claims 1-4, characterized in that, The reaction temperature for the aldol condensation reaction is 260℃~280℃.

6. The preparation method according to any one of claims 1-4, characterized in that, The reaction time for the aldol condensation reaction is 0.15 h to 4 h.

7. The preparation method according to any one of claims 1-4, characterized in that, The reaction time for the aldol condensation reaction is 0.4 h to 2 h.

8. The preparation method according to any one of claims 1-4, characterized in that, The reaction time for the aldol condensation reaction is 1 hour.

9. The preparation method according to any one of claims 1-4, characterized in that, The mass of the catalyst is 1% to 40% of the mass of cyclopropyl methyl ketone.

10. The preparation method according to any one of claims 1-4, characterized in that, The mass of the catalyst is 6% to 10% of the mass of cyclopropyl methyl ketone.

11. The preparation method according to any one of claims 1-4, characterized in that, The mass of the catalyst is 6% of the mass of cyclopropyl methyl ketone.

12. The preparation method according to any one of claims 1-4, characterized in that, The post-processing includes: adding a desiccant to the collected liquid, filtering and collecting the filtrate, distilling under reduced pressure, and collecting the fraction at 10 Pa and 120 °C, which is 1,3-bicyclopropyl-2-buten-1-one.

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