A catalyst for preparing 1,3-dicyclopropyl-2-buten-1-one and a method for preparing 1,3-dicyclopropyl-2-buten-1-one

Abstract

The application discloses a catalyst for preparing 1,3-dicyclopropyl-2-buten-1-one and a preparation method of 1,3-dicyclopropyl-2-buten-1-one, the catalyst comprises a carrier loaded with an active component; the carrier is porous structure Al2O3 prepared by calcining Al(NO3)3.9H2O, has a specific surface area of 260-430 m 2 / g; and the active component is selected from a combination of one or more of Sc, Y, La, Ce, Pr and Nd. The preparation method comprises: under the condition that a water absorbent is present, cyclopropyl methyl ketone is subjected to aldol self-condensation reaction under the catalysis of the catalyst to prepare 1,3-dicyclopropyl-2-buten-1-one. In the application, the catalyst adopts a rare earth oxide with moderate alkalinity which is loaded on the Al2O3 carrier, and the specific surface area of the carrier is large, so that the distribution uniformity of the catalyst in the liquid phase reaction system can be enhanced, the aldol condensation reaction can be more effectively promoted, the water absorbent is added in the reaction process, the water absorbent can react with the water generated by the aldol condensation reaction, the reaction equilibrium is pushed to move to the right, and the purpose of improving the reaction yield is achieved.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically, it relates to a catalyst for preparing 1,3-bicyclopropyl-2-buten-1-one and a method for preparing 1,3-bicyclopropyl-2-buten-1-one. Background Technology

[0002] Liquid fuels in aerospace are the energy source for propulsion systems and the working fluid for engines. The vast majority of existing fuels are derived from petroleum refining and distillation. While abundant and inexpensive, these fuels have limitations due to their low density and calorific value, and their molecular structure cannot be altered, thus failing to meet the higher performance requirements of propulsion systems. Therefore, developing new fuel synthesis technologies is of paramount importance.

[0003] As a method to increase molecular weight and density, carbon chain growth reactions can effectively improve the calorific value of fuels, thereby enhancing fuel performance. Aldol condensation is a crucial means of C / C bond formation and carbon chain growth. Cyclopropyl ketone, a commonly used pharmaceutical raw material, possesses a three-membered ring structure and additional strain energy. Through aldol self-condensation, eliminating one molecule of water yields the product 1,3-biscyclopropyl-2-buten-1-one. This product also possesses the high-energy structure of cyclopropane and can be used in the preparation of liquid hydrocarbon fuels, improving key properties such as calorific value and density; it is an important synthetic intermediate.

[0004] Cyclopropyl methyl ketone (CMK) exhibits significant steric hindrance, rendering commonly used aldol condensation reaction conditions, such as those using inorganic base catalysts like sodium hydroxide, potassium phosphate, and cesium carbonate, insufficiently active to generate 1,3-dicyclopropyl-2-buten-1-one. Furthermore, superbases such as sodium methoxide, potassium tert-butoxide, and lithium diisopropylaminodioxide, while generating 1,3-dicyclopropyl-2-buten-1-one, also promote a Michael addition reaction between 1,3-dicyclopropyl-2-buten-1-one and CMK, leading to trimers or even polymers, severely reducing the reaction's selectivity.

[0005] Because the equilibrium of the aldol self-condensation reaction of ketones is heavily biased towards the reactants, at least one product must be removed during the reaction to promote the forward reaction. In existing techniques, Soviet researchers used potassium hydroxide as both a catalyst and a dehydrating agent to prepare 1,3-bicyclopropyl-2-buten-1-one by heating under reflux, but the yield was only 20% and the selectivity was less than 40%, wasting raw materials and generating difficult-to-treat solid alkali and polymer waste. Other methods utilize solid dehydrating agents such as aluminum tert-butoxide or calcium hydride to catalyze this reaction, achieving yields exceeding 50%, but these substances deteriorate upon absorbing water and cannot be recycled. All existing methods suffer from low yields and selectivity, easy catalyst deactivation, and the inability to recycle and reuse catalysts, generating large amounts of waste and hindering cost reduction.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the shortcomings of the prior art and provide a catalyst for the preparation of 1,3-bicyclopropyl-2-buten-1-one and a method for preparing 1,3-bicyclopropyl-2-buten-1-one. The catalyst has higher catalytic activity and more uniform distribution in the liquid-phase reaction system. With the addition of a dehydrating agent to the reaction system, the reaction equilibrium is shifted to the right, which improves the yield and selectivity of the reaction. The catalyst is not lost and is easy to separate after the reaction, resulting in less waste. This provides a feasible solution for large-scale industrial production.

[0008] To solve the above-mentioned technical problems, the basic concept of the technical solution adopted by the present invention is as follows:

[0009] The present invention provides a catalyst for preparing 1,3-bicyclopropyl-2-buten-1-one, comprising a support and an active component supported on the support;

[0010] The carrier is a porous Al2O3, obtained by calcination of Al(NO3)3·9H2O, with a microstructure of 260–430 μm. 2 Specific surface area per g;

[0011] The active component is selected from one or more combinations of Sc, Y, La, Ce, Pr, and Nd.

[0012] In this invention, the catalyst is a supported catalyst. The active component exists as an oxide on the support, possessing both acidic and basic properties. Therefore, when used as a catalyst, it can activate the ketone carbonyl group and deprotonate it, effectively promoting the aldol condensation reaction. Furthermore, the basicity of rare earth oxides is weaker than that of alkali metals, alkaline earth metal oxides, and hydroxides. Under suitable reaction conditions, this prevents the product from further reacting with cyclopropyl ketone to form a polymer, thus reducing side reactions and increasing the yield.

[0013] Using porous Al2O3 prepared by calcination of Al(NO3)3·9H2O as a support for loading active components is beneficial to increasing the specific surface area of ​​the support. On the one hand, it enhances the uniformity of catalyst distribution in the liquid phase reaction system, and on the other hand, it can increase the loading of active components and make them uniformly dispersed, thereby significantly improving catalytic performance.

[0014] In a further embodiment, the carrier is prepared by calcining Al(NO3)3·9H2O in a muffle furnace at a temperature of 400–650°C;

[0015] Preferably, the calcination temperature is 500℃.

[0016] In the above scheme, the specific surface area of ​​the carrier can reach 260–430 m². 2 At a concentration of / g, the catalyst can achieve uniform dispersion in the liquid-phase reaction system, is less prone to aggregation and deactivation, and has a longer lifespan. Simultaneously, it can achieve higher loading of active components, and the active components are more easily and uniformly dispersed in the support, resulting in better catalytic performance. Furthermore, the catalyst possesses suitable acidity and basicity to activate the ketone carbonyl group and deprotonate it, respectively, ensuring effective promotion of the aldol condensation reaction.

[0017] In a preferred embodiment, the catalyst is a powder catalyst.

[0018] In one specific embodiment, the powder catalyst is prepared by an equal-volume impregnation method. That is, the corresponding metal nitrate aqueous solution is prepared according to the percentage of the active component to the carrier mass. The powdered Al2O3 carrier is added to the metal nitrate aqueous solution at one time under vigorous stirring. After the mixture returns to room temperature, it is vacuum dried and then heated to 400-650°C in an air atmosphere using a muffle furnace at a heating rate of 5-30°C / min. It is calcined at this temperature for a period of time and then cooled to room temperature to obtain the spherical powder catalyst.

[0019] In the above scheme, the catalyst preparation method is simple, it can be prepared in batches for industrial scale-up, and its acid-base strength is reasonable. It is also easy to regenerate by air calcination, does not easily accumulate carbon, and has good recyclability.

[0020] In a further embodiment, the active component is selected from one or more combinations of Y, La, Ce, Pr, and Nd;

[0021] Preferably, the active component is selected from one or more combinations of La, Ce, and Pr;

[0022] More preferably, the active ingredient is La.

[0023] In the above schemes, when the active components are Y, La, Ce, Pr, and Nd, the yields of 1,3-bicyclopropyl-2-buten-1-one are all above 85%, and the selectivity is above 99%. Among these, when the active components are La, Ce, and Pr, the reaction yield can be further increased to over 90%. When the active component is La, the catalyst exhibits the strongest basicity and highest activity, achieving a balance between reaction yield and selectivity, thus demonstrating the optimal catalytic effect.

[0024] In a further embodiment, the active component accounts for 1% to 12% of the mass percentage of the carrier, preferably 6% to 12%, and more preferably 12%.

[0025] Tests revealed that when the loading of the active component (i.e., the percentage of the active component by mass of the support) was limited to the above range, the reaction yield increased with increasing the loading of the active component. However, after the loading reached 12%, further increasing the loading of the active component did not improve the reaction yield. Therefore, under the premise of ensuring high product yield and selectivity, a mass percentage of the active component in the support of 12% is preferred.

[0026] The present invention also provides a method for preparing 1,3-bicyclopropyl-2-buten-1-one, comprising: under the presence of a desiccant, cyclopropyl methyl ketone undergoes an aldol self-condensation reaction under the catalysis of the catalyst described above for preparing 1,3-bicyclopropyl-2-buten-1-one, to prepare 1,3-bicyclopropyl-2-buten-1-one;

[0027] The reaction temperature for the aldol self-condensation reaction is 100–160°C, preferably 120–160°C, and more preferably 120°C.

[0028] In this invention, 1,3-biscyclopropyl-2-buten-1-one is prepared by catalyzing the aldol self-condensation reaction of cyclopropyl methyl ketone using the aforementioned catalyst, which effectively improves the yield and selectivity of the reaction product. The catalyst employs a porous support and active components, which, compared to traditional free inorganic solid base catalysts, increases the number of catalytic sites, reduces catalyst agglomeration, minimizes catalyst deactivation, facilitates separation after the reaction, minimizes waste, and simplifies the process, laying the foundation for large-scale industrial production.

[0029] The reaction process is carried out in the presence of a desiccant. The water generated by the aldol self-condensation reaction of cyclopropyl methyl ketone can react with the desiccant and be removed from the reaction system. This can shift the equilibrium of the aldol self-condensation reaction to the right, thereby increasing the reaction yield.

[0030] In addition, within the above-mentioned limited reaction temperature, cyclopropyl methyl ketone can undergo aldol self-condensation reaction under the catalysis of the catalyst. However, if the reaction temperature is too high, side reactions will occur, reducing the reaction selectivity; if the reaction temperature is too low, the reaction will be too slow, reducing production efficiency.

[0031] In a further embodiment, the mass of the catalyst is 1% to 5% of the mass of cyclopropyl methyl ketone;

[0032] Preferably, the mass of the catalyst is 3% of the mass of cyclopropyl methyl ketone.

[0033] In this invention, when the mass of the catalyst and the mass of cyclopropyl methyl ketone are within the above-mentioned limits, the catalyst has a good catalytic effect, can effectively reduce the generation of by-products, and is convenient for post-processing and has high production efficiency. If the amount of catalyst used is too large, it will lead to a decrease in product selectivity; while if the amount of catalyst used is too small, it will prolong the reaction time and reduce production efficiency.

[0034] In a further embodiment, the absorbent is acetonitrile.

[0035] Acetonitrile is a green, low-boiling-point, volatile solvent that can be easily removed by atmospheric distillation and recycled. In this invention, acetonitrile is selected as the desiccant, which makes it easy to remove unreacted acetonitrile after the reaction is complete, and the unreacted acetonitrile can be recycled, which helps to reduce costs.

[0036] Specifically, in the above scheme, the water generated from the self-condensation of cyclopropyl methyl ketone aldehyde can react with acetonitrile on the catalyst surface to selectively produce acetamide. Acetamide has a solubility in water exceeding 2 g / mL and can be easily removed by washing with water, thus readily separating it from the water-insoluble product 1,3-bicyclopropyl-2-buten-1-one. Acetamide is mainly used as an organic solvent, and can also be used as a plasticizer and peroxide stabilizer, an anti-acid agent in cosmetics, and an antidote for organofluorine pesticides, exhibiting a wide range of applications. After the reaction, the generated acetamide is separated and collected, serving as a byproduct in the preparation of 1,3-bicyclopropyl-2-buten-1-one.

[0037] Although other nitrile solvents can also react with water, such as butyronitrile and benzonitrile, they are often highly toxic, or some solvents have high boiling points and are difficult to separate. Therefore, acetonitrile was chosen as the desiccant.

[0038] In a preferred embodiment, the molar ratio of acetonitrile to cyclopropane ketone is 1.0 to 2.0:1, preferably 1.2:1.

[0039] In the above scheme, to ensure the reaction yield for preparing 1,3-bicyclopropyl-2-buten-1-one, acetonitrile needs to be in excess with cyclopropyl methyl ketone to fully absorb the water generated in the reaction. However, excessive acetonitrile will dilute the reaction system and reduce the reaction rate.

[0040] In a further embodiment, the reaction time of the aldol self-condensation reaction is 0.5 to 6 hours, preferably 3 to 4 hours, and more preferably 4 hours.

[0041] In the above scheme, the reaction time refers to the contact time between the reactants 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, thus 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.

[0042] In a further embodiment, the reaction pressure is 0.1 MPa to 5 MPa, preferably 0.1 MPa to 1.2 MPa.

[0043] In one specific implementation, the reactants are loaded into a reaction vessel for reaction. If the reaction pressure is too high, the pressure-bearing requirements of the inner wall material of the reaction vessel need to be further improved; insufficient pressure-bearing capacity will pose a safety hazard.

[0044] In a further embodiment, the purity of the cyclopropyl ketone is not less than 98.5%, and the purity of the acetonitrile is not less than 98%.

[0045] In the above scheme, the high purity of the raw material cyclopropyl ketone is beneficial to the smooth progress of the reaction. Low purity will prolong the reaction time and may even poison the catalyst. Furthermore, both cyclopropyl ketone and acetonitrile are industrial raw materials, readily available for purchase.

[0046] In a further embodiment, the preparation method includes the following steps:

[0047] Add cyclopropanone, dehydrating agent and catalyst to the reactor, adjust the temperature to the reaction temperature, and maintain the temperature to carry out the reaction;

[0048] After the reaction was completed, the reaction solution with the catalyst removed was post-treated to obtain the product 1,3-bicyclopropyl-2-buten-1-one.

[0049] In one specific implementation, after loading the catalyst and reactants into the reactor, N2 replacement is performed, and then the reaction temperature is adjusted. After maintaining the reactor at a constant temperature, the reaction is continued until completion. Afterward, the catalyst is separated by filtration, and the reaction solution is distilled to remove unreacted cyclopropyl ketone and acetonitrile. Finally, acetamide is removed by washing with water to obtain 1,3-bicyclopropyl-2-buten-1-one.

[0050] In the above scheme, stirring is applied in the reactor to ensure that cyclopropyl methyl ketone and acetonitrile are in full contact with the catalyst, generating 1,3-bicyclopropyl-2-buten-1-one and acetamide. Because the water generated by the self-condensation of cyclopropyl methyl ketone aldehydes can be efficiently removed, the reaction equilibrium is continuously shifted to the right, increasing the yield of 1,3-bicyclopropyl-2-buten-1-one.

[0051] In a further embodiment, the post-processing includes: distilling the reaction solution using a spiked distillation column to distill off fractions at atmospheric pressure of 81±1℃ and 114±1℃; adding deionized water to the residue; shaking and separating the liquid to release the lower aqueous phase; and the upper organic phase is the product 1,3-bicyclopropyl-2-buten-1-one.

[0052] Preferably, the fractions distilled at atmospheric pressure at 81±1℃ and 114±1℃ are collected separately.

[0053] In the above scheme, the fractions distilled at atmospheric pressure (81±1℃ and 114±1℃) are unreacted acetamide and cyclopropyl ketone, respectively, which can be collected and recycled. The lower aqueous phase obtained after washing with deionized water is an aqueous solution of acetamide.

[0054] The preparation of 1,3-bicyclopropyl-2-buten-1-one according to the preparation method of the present invention yielded a reaction yield of up to 97% and a selectivity of up to 99%.

[0055] By adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0056] 1. In this invention, rare earth metals supported on porous Al2O3 are used as catalysts to catalyze the aldol self-condensation reaction of cyclopropyl methyl ketone to prepare 1,3-biscyclopropyl-2-buten-1-one. The basicity is reasonable, which can avoid the formation of polymers and improve the reaction selectivity.

[0057] 2. In this invention, the catalyst support is prepared by calcining Al(NO3)3·9H2O, which has a porous structure and a large specific surface area. On the one hand, it increases the uniformity of catalyst distribution in the liquid-phase reaction system, making it less prone to agglomeration, which is conducive to the full contact between cyclopropyl methyl ketone and the catalyst and ensures the catalytic effect. On the other hand, it can increase the loading of active components and make them uniformly dispersed, thereby significantly improving catalytic performance. The catalyst is not easily deactivated and has a long lifespan, which can effectively promote the aldol condensation reaction.

[0058] 3. In this invention, a desiccant is added to the reaction system, especially acetonitrile, which can react with the water generated by the self-condensation reaction of aldol, pushing the reaction equilibrium to the right and increasing the yield of the product; at the same time, the acetamide generated by the reaction of acetonitrile and water has a wide range of industrial applications and can be easily recycled.

[0059] 4. The process used in this invention improves the yield and selectivity of the product, makes the reaction system easy to separate, is simple in process, and is easy to operate, which is conducive to process scale-up and has low cost, laying the foundation for subsequent large-scale industrial production of the product.

[0060] The specific embodiments of the present invention will be described in further detail below. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0062] Example 1

[0063] A. Catalyst preparation:

[0064] (1) Support preparation: 2000g of Al(NO3)3·9H2O support was weighed, placed in a corundum crucible, and placed in a muffle furnace. The temperature was increased to 500℃ at 30℃ / min and held for 4h in a dry air atmosphere. After cooling to room temperature, 272g of white powder was obtained, which is the Al2O3 support. The specific surface area of ​​the Al2O3 support was measured to be 282m². 2 / g;

[0065] (2) Impregnation: Weigh 102g of La(NO3)3·6H2O, dissolve it in 218mL of deionized water, and immediately add the entire solution to a beaker containing the above Al2O3 support. Sonicate for 20min to make the impregnation solution evenly distributed on the surface of the support. Dry it in a forced air at 120℃ for 1h to obtain the catalyst precursor.

[0066] (3) Calcination: Take out the dried catalyst precursor, put it into the corundum crucible, place it in the muffle furnace, heat it to 600℃ at 5℃ / min in a dry air atmosphere and keep it at 4h, cool it to room temperature, take out the sample and weigh a total of 310g, which is the 12% La@Al2O3 powder catalyst.

[0067] B. Preparation of 1,3-bicyclopropyl-2-buten-1-one:

[0068] (1) 1.20 kg of cyclopropyl methyl ketone, 703 g of acetonitrile, and 36 g of 12% La@Al2O3 powder catalyst were loaded into a 2.5 L reactor, replaced with N2 three times, heated to 120 °C and kept at that temperature, and stirred vigorously for 4 h.

[0069] (2) Cool to room temperature and filter to separate the catalyst; transfer the reaction solution into a 2.5L round bottom flask, heat and distill, and use a 300mm spiked distillation column to collect the fractions at 81℃±1℃ and 114℃±1℃ under normal pressure, which are the unreacted acetonitrile and cyclopropionate ketone.

[0070] (3) Transfer the residual liquid to a 2.5L separatory funnel, add 750mL of deionized water, shake, let stand for 1h, separate the liquid, and release the lower aqueous phase liquid, which is the acetamide aqueous solution. The upper organic phase is the product 1,3-bicyclopropyl-2-buten-1-one.

[0071] Comparative Example 1

[0072] Based on Example 1, the 12% La@Al2O3 powder catalyst was replaced with granular KOH, and other preparation conditions remained unchanged. 1,3-Bicyclopropyl-2-buten-1-one was prepared according to steps (1) to (3) of step B in Example 1.

[0073] Comparative Example 2

[0074] Based on Example 1, the 12% La@Al2O3 powder catalyst was replaced with powdered La2O3, and other preparation conditions remained unchanged. 1,3-Bicyclopropyl-2-buten-1-one was prepared according to steps (1) to (3) of step B in Example 1.

[0075] Comparative Example 3

[0076] Based on Example 1, acetonitrile was not added in step (1) of step B, and other preparation conditions remained unchanged, to prepare 1,3-bicyclopropyl-2-buten-1-one.

[0077] Comparative Example 4

[0078] Based on Example 1, step (1) in step A is omitted, and the Al2O3 carrier in step (2) is replaced with spherical Al2O3 (40 mesh spherical, with a specific surface area of ​​approximately 180 m²). 2 / g, with an average pore size of approximately 50 nm), and with all other preparation conditions remaining unchanged, 1,3-bicyclopropyl-2-buten-1-one was finally obtained.

[0079] Experimental Example 1

[0080] This experiment tested the yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one in Example 1 and Comparative Examples 1-4. The test results are shown in Table 1 below.

[0081] Table 1

[0082]

[0083] In Example 1, using the preparation method of the present invention, the yield of 1,3-bicyclopropyl-2-buten-1-one was as high as 97%, and the selectivity was greater than 99%, indicating that the scheme of the present invention effectively improves the yield and selectivity.

[0084] In contrast, the catalyst used in Comparative Example 1 was KOH, which was too alkaline. As a large amount of polymer was generated, the yield and selectivity of 1,3-bicyclopropyl-2-buten-1-one were both low.

[0085] In Comparative Example 2, powdered La2O3 was used as a catalyst. Although it had high selectivity, the specific surface area of ​​powdered La2O3 was very small and it was easy to agglomerate, resulting in insufficient catalytic sites and a very low yield.

[0086] In Comparative Example 3, no acetonitrile was added. Since the equilibrium of the aldol self-condensation reaction was severely biased to the left, it was impossible to shift the equilibrium to the right without removing the product water, resulting in an extremely low yield.

[0087] In Comparative Example 4, spherical Al2O3 was used as the catalyst support. The specific surface area of ​​this spherical Al2O3 was significantly lower than that of the porous Al2O3 support used in this application. Due to the poor dispersibility of the spherical Al2O3, it was found during the actual preparation process that the catalyst easily agglomerated, leading to insufficient contact between the catalyst and the reaction liquid, resulting in a low final yield. This indicates that the catalyst using spherical Al2O3 as the support is not suitable for liquid-phase reactions.

[0088] Experimental Example 2

[0089] This experimental example was used to investigate the effect of the active component of the catalyst on the self-condensation effect of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the rare earth element in the nitrate in step A (2) was changed to change the active component of the catalyst. The other preparation steps and processes were the same as in Example 1, resulting in Examples 2-7.

[0090] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 2 below.

[0091] Table 2

[0092]

[0093] As shown in Table 2, when the active components are Sc, Y, La, Ce, Pr, and Nd, they can all catalyze the aldol self-condensation reaction of cyclopropyl methyl ketone, with yields of 1,3-biscyclopropyl-2-buten-1-one exceeding 76% and selectivity exceeding 99%. This is because rare earth oxides possess both suitable basicity and acidity, which respectively deprotonate and activate the ketone carbonyl group, resulting in high product yields; and the basicity is not too strong, preventing further reaction between the product and cyclopropyl methyl ketone, thus ensuring high selectivity.

[0094] Furthermore, when the active components are Y, La, Ce, Pr, and Nd, a yield of not less than 87% can be achieved; when the active components are La, Ce, and Pr, a yield of not less than 91% can be achieved; and under the same conditions, when La is selected as the active component, the yield is as high as 97%, which is the highest yield.

[0095] Experimental Example 3

[0096] This experimental example was used to investigate the effect of the loading of the active component of the catalyst on the self-condensation effect of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the amount of La(NO3)3·6H2O in step (2) of step A was changed to change the mass percentage of the active component in the support. The other preparation steps and processes were the same as in Example 1, resulting in Examples 8-13.

[0097] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 3 below.

[0098] Table 3

[0099]

[0100] As shown in Table 3, when the mass percentage of the active component in the support is between 1% and 12%, the selectivity for preparing 1,3-bicyclopropyl-2-buten-1-one is greater than 99%, and the yield increases significantly. In particular, when the mass percentage of the active component in the support is between 6% and 12%, the yield of 1,3-bicyclopropyl-2-buten-1-one is higher than 80%. When the mass percentage of the active component in the support is 12%, the yield of the product reaches as high as 97%, and the selectivity reaches as high as 99%. However, further increasing the loading of the active component does not further improve the yield.

[0101] Therefore, to ensure high product yield and selectivity without increasing costs, it is unnecessary to use excessively high loading rates. Instead, the active component should be controlled to account for 12% of the mass percentage of the support. If the active component accounts for too low a mass percentage of the support, the catalyst activity will be insufficient, leading to a decrease in yield.

[0102] Test Example 4

[0103] This experiment was conducted to investigate the effect of reaction temperature on the self-condensation of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the reaction temperature in step B (1) was changed, while the other preparation steps and processes were the same as in Example 1, resulting in Examples 14-16.

[0104] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 4 below.

[0105] Table 4

[0106]

[0107] As can be seen from the data in Table 4, when the reaction temperature is 100-160℃, the yield of 1,3-bicyclopropyl-2-buten-1-one is above 60%; among them, when the reaction temperature is 120-160℃, the yield can reach 90% or above; especially when the reaction temperature is 120℃, the yield is as high as 97% and the selectivity is as high as 99%.

[0108] However, at reaction temperatures of 140℃ or 160℃, the selectivity decreases compared to the reaction temperature of 120℃. This shows that if the reaction temperature is too high, polymers are easily formed, reducing the selectivity of the reaction. Conversely, if the reaction temperature is too low, the reaction will be too slow, reducing production efficiency.

[0109] Experimental Example 5

[0110] This experimental example was used to investigate the effect of catalyst dosage on the self-condensation effect of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the amount of catalyst added in step B (1) was changed, and the other preparation steps and processes were the same as in Example 1, resulting in Examples 17-21.

[0111] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 5 below.

[0112] Table 5

[0113]

[0114] As can be seen from the data in Table 5, when the mass of the catalyst is 0.2% to 5% of the mass of cyclopropyl methyl ketone, the yield of the product gradually increases with the increase of the catalyst mass. However, when the mass of the catalyst accounts for more than 3% of the mass of cyclopropyl methyl ketone, the increase of the catalyst mass has no significant effect on the yield of the product, but instead reduces the selectivity of the product.

[0115] This is because if the mass percentage of the catalyst relative to the mass of cyclopropyl methyl ketone is too high, i.e., when the catalyst dosage is large, its adsorption of the raw materials increases, which can promote deep reactions between the raw materials and / or products, generating byproducts, reducing the selectivity for preparing 1,3-dicyclopropyl-2-buten-1-one, and also hindering post-reaction processing. Conversely, if the mass percentage of the catalyst relative to the mass of cyclopropyl methyl ketone is too low, as in Example 17, it will reduce the product yield, prolong the reaction time, and decrease production efficiency. Therefore, while ensuring the acquisition of the target product, the mass percentage of the catalyst relative to the mass of cyclopropyl methyl ketone is controlled to be 1% to 5%, preferably 3%.

[0116] Experimental Example 6

[0117] This experiment was used to investigate the effect of reaction time on the self-condensation effect of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the stirring reaction time in step B (1) was changed, and the other preparation steps and processes were the same as in Example 1, resulting in Examples 22-27.

[0118] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 6 below.

[0119] Table 6

[0120]

[0121] As can be seen from the data in Table 6, the product yield gradually increases with the extension of reaction time. When the reaction time reaches 4 hours, the yield increases to 97%, and the yield no longer increases after further extending the reaction time. If the reaction time is too short, the raw materials are not fully converted, and the yield decreases; if the reaction time is too long, the yield cannot be further increased, resulting in energy waste and reduced production efficiency. Therefore, in this invention, the reaction time is preferably controlled between 3 and 4 hours, with the optimal reaction time being 4 hours.

[0122] Experimental Example 7

[0123] This experimental example was used to investigate the effect of the type of desiccant on the self-condensation effect of cyclopropane ketone aldehyde. Specifically, referring to the preparation process of Example 1, only the acetonitrile in step B (1) was replaced with other desiccant, and the other preparation steps and processes were the same as in Example 1, resulting in Examples 28-36.

[0124] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 7 below.

[0125] Table 7

[0126]

[0127] As can be seen from the data in Table 7, acetonitrile achieves high yield and selectivity when used as a desiccant. The yields of other desiccant agents do not exceed those of acetonitrile, and benzonitrile and butyronitrile are highly toxic and unsuitable for mass production. Aluminum isopropoxide and titanium isopropoxide are also too expensive and unsuitable for mass production.

[0128] Experimental Example 8

[0129] This experimental example was used to investigate the effect of the amount of desiccant on the self-condensation effect of cyclopropane acetal. Specifically, referring to the preparation process of Example 1, only the amount of acetonitrile added in step B (1) was changed, and the other preparation steps and processes were the same as in Example 1, resulting in Examples 37-42.

[0130] In this experimental example, the yield and selectivity of the product 1,3-bicyclopropyl-2-buten-1-one were tested, and the results are shown in Table 8 below.

[0131] Table 8

[0132]

[0133] As shown in Table 8, the yield of 1,3-bicyclopropyl-2-buten-1-one increases with the increase of acetonitrile dosage. When the molar ratio reaches 1.0:1, the yield is not less than 85%. However, when the molar ratio of acetonitrile to cyclopropyl methyl ketone exceeds 1.2:1, the yield of 1,3-bicyclopropyl-2-buten-1-one no longer increases. To avoid material waste due to excessive acetonitrile dosage, the molar ratio of acetonitrile to cyclopropyl methyl ketone is controlled at 1.0 to 2.0:1, preferably at 1.2:1.

[0134] 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 reaction is carried out in a liquid-phase reaction system. Includes the following steps: Cyclopropyl methyl ketone, acetonitrile (a dehydrating agent), and catalyst were added to the reactor. The temperature was adjusted to 120-160°C and kept at that temperature. Cyclopropyl methyl ketone underwent an aldol self-condensation reaction under the catalysis of the catalyst to prepare 1,3-biscyclopropyl-2-buten-1-one. After the reaction is completed, the catalyst is separated by filtration, and the reaction solution after removing the catalyst is post-treated to obtain the product 1,3-bicyclopropyl-2-buten-1-one; wherein, the post-treatment includes removing unreacted cyclopropyl ketone and acetonitrile from the reaction solution by distillation, and then removing acetamide by washing with water. The catalyst comprises a porous Al2O3 support and an active component supported on the support; the active component is selected from one or more elements selected from Sc, Y, La, Ce, Pr and Nd, and exists in the form of oxides when supported on the support, and has certain acidity and basicity. The porous Al2O3 was prepared by calcining Al(NO3)3·9H2O in a muffle furnace under dry air atmosphere at a temperature of 400~650℃, and has a microstructure of 260~430 μm. 2 Specific surface area per g.

2. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 1, characterized in that, The reaction temperature for the aldol self-condensation reaction is 120°C.

3. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 1, characterized in that, The calcination temperature of Al(NO3)3·9H2O in the muffle furnace is 500℃.

4. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 1, characterized in that, The active component is selected from one or a combination of elements selected from Y, La, Ce, Pr, and Nd.

5. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 4, characterized in that, The active component is selected from one or more elements selected from La, Ce, and Pr.

6. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 5, characterized in that, The active component is La.

7. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 1, characterized in that, In the catalyst, the active component accounts for 1% to 12% of the mass percentage of the support.

8. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 7, characterized in that, The active component accounts for 6% to 12% of the mass of the carrier.

9. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 8, characterized in that, The active component accounts for 12% of the mass of the carrier.

10. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to any one of claims 1-9, characterized in that, The mass of the catalyst is 1% to 5% of the mass of cyclopropyl ketone.

11. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 10, characterized in that, The mass of the catalyst is 3% of the mass of cyclopropyl methyl ketone.

12. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to any one of claims 1-9, wherein the molar ratio of acetonitrile to cyclopropyl methyl ketone is 1.0~2.0:

1.

13. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 12, characterized in that, The molar ratio of acetonitrile to cyclopropionate is 1.2:

1.

14. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to any one of claims 1-9, characterized in that, The reaction time for the aldol self-condensation reaction is 0.5~6h.

15. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 14, characterized in that, The reaction time for the aldol self-condensation reaction is 3-4 hours.

16. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 15, characterized in that, The reaction time for the aldol self-condensation reaction is 4 hours.

17. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to any one of claims 1-9, characterized in that, The post-processing includes: distilling the reaction solution using a spiked distillation column to distill off fractions at atmospheric pressure of 81±1℃ and 114±1℃, adding deionized water to the residue, shaking and separating the liquid, releasing the lower aqueous phase, and the upper organic phase is the product 1,3-bicyclopropyl-2-buten-1-one.

18. The method for preparing 1,3-bicyclopropyl-2-buten-1-one according to claim 17, characterized in that, The fractions distilled at atmospheric pressure at 81±1℃ and 114±1℃ were collected separately.

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