Preparation method of 1, 3-dicyclopropyl-2-butene-1-one compound

Abstract

The invention provides a preparation method of a 1, 3-dicyclopropyl-2-butene-1-one compound, belongs to the technical field of organic synthesis catalytic materials, and aims to solve the technical problem of low yield of ketene compounds. The preparation method of the ketene compound comprises the following steps: mixing cyclopropyl methyl ketone and a diaspore catalyst, and carrying out condensation reaction to generate 1, 3-dicyclopropyl-2-butene-1-ketone. The preparation method of the diaspore catalyst is simple and suitable for large-scale preparation. The surface of the material is rich in hydroxyl, and the material has the advantages of strong alkalinity, high catalytic efficiency and stable cycle activity. The diaspore has higher conversion efficiency and selectivity for self-condensation of cyclopropyl methyl ketone molecules, and can realize higher conversion rate under mild conditions.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis catalytic materials, and in particular relates to a method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound. Background Art

[0002] With the rapid development of my country's aerospace industry, the volume of payloads and launches has increased annually, posing a challenge to the development of propellants. Syntin, a high-energy fuel containing a cyclopropane structure, boasts a calorific value of 46 MJ / L, significantly superior to the traditional fuel RJ-4 (calorific value of 39 MJ / L). Developing Syntin as a replacement for traditional fuels will help advance my country's aerospace industry.

[0003] The route of synthesizing Syntin from the cheap industrial raw material cyclopropyl methyl ketone has the advantage of high atomic utilization. The traditional route is to subject the raw materials to ketone hydrazine condensation reaction, internal cyclization reaction and denitrogenation reaction. The second step of this route is a homogeneous catalytic reaction induced by strong acid, which has the problems of low selectivity of dimerization product (selectivity is 61%) and poor catalyst recycling performance. In order to synthesize Syntin by multiple routes, a reaction route with 1,3-dicyclopropyl-2-butene-1-one (enone) as an intermediate was developed, such as Figure 1 As shown. Cyclopropyl methyl ketone self-condenses and dehydrates to produce enone, and then synthesizes the product through condensation reaction of enone with hydrazine and denitrogenation reaction. According to previous explorations, the selectivity of the second and third steps of the reaction reached more than 90%. For the first step reaction, it is difficult to activate the C=O bond and α-H bond due to the large steric hindrance of cyclopropyl methyl ketone due to its cyclopropane structure. Traditional homogeneous catalysts (HCl, KOH, aluminum tert-butoxide) rely on the adsorption / collision of active sites with cyclopropyl methyl ketone molecules, which are prone to polymerization and difficulty in catalyst separation. For example, Patent Publication No. CN114478223A discloses a 1,3-dicyclopropyl-2-butene-1-one and a preparation method thereof. Cyclopropyl methyl ketone is used as a raw material, cyclopropyl methyl ketone is added to the reaction flask, and then an alkaline substance that can both dehydrate and absorb water and act as a catalyst is selected for condensation reaction.

[0004] Heterogeneous catalysts have the advantages of easy regulation of active site structure and easy separation of catalysts. For example, Patent Publication No. CN 118287162A discloses a catalyst for preparing 1,3-dicyclopropyl-2-butene-1-one and a method for preparing 1,3-dicyclopropyl-2-butene-1-one. The catalyst comprises a carrier loaded with an active component; the carrier is a porous Al2O3 prepared by calcining Al(NO3)3·9H2O, with a molecular weight of 260 to 430 nm. 2 / g specific surface area; the active component is selected from a combination of one or more of Sc, Y, La, Ce, Pr, and Nd. The catalyst carrier lacks catalytic properties. The preparation method comprises: in the presence of a water absorbent, cyclopropyl ketone undergoes an aldol self-condensation reaction under the catalytic action of a catalyst to produce 1,3-dicyclopropyl-2-butene-1-one. However, this patent still requires the use of acetonitrile as a dehydrating agent, which still presents issues such as separation difficulties and environmental issues. Summary of the Invention

[0005] In response to the above technical problems, the present invention proposes a method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound, which has the advantages of easy regulation of the active site structure and easy separation of the catalyst, and can improve the selectivity and cyclic stability of the product enone.

[0006] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0007] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound is characterized in that cyclopropyl methyl ketone and a diaspore catalyst are mixed to carry out a condensation reaction to generate 1,3-dicyclopropyl-2-butene-1-one.

[0008] The preparation method of the diaspore catalyst comprises: dissolving aluminum salt in water to prepare an aluminum salt solution, adding a precipitant and a morphology control agent to obtain aluminum hydroxide gel; subjecting the aluminum hydroxide gel to a hydrothermal reaction, washing, drying and grinding to obtain aluminum hydroxide powder; and subjecting the precursor to an alkali etching treatment, washing and drying, to obtain the diaspore catalyst.

[0009] The aluminum salt is any one of aluminum sulfate 18hydrate, hydrated aluminum nitrate, aluminum chloride, and aluminum acetate; and the concentration of the aluminum salt solution is 0.01-0.1 mol / L.

[0010] The precipitant is ammonia water, and the molar ratio of ammonia monohydrate to aluminum salt in the ammonia water is not greater than 1.

[0011] The morphology control agent is ammonium fluoride or sodium borofluoride; the mass ratio of the morphology control agent to the aluminum salt is 0.01-0.1:1.

[0012] The temperature of the hydrothermal reaction is 110-180° C., and the time is 4 hours.

[0013] The alkaline etching treatment comprises the following steps: adding aluminum hydroxide powder into an alkaline solution for etching.

[0014] The alkali in the alkaline solution is an organic base; the organic base is any one of tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide;

[0015] The concentration of the alkaline solution is 10%-25wt%; the etching time is 0.5-3h.

[0016] The method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound according to claim 1, characterized in that the amount of the diaspore catalyst added is 1-15wt% of the cyclopropyl methyl ketone; the condensation reaction temperature is 90-160°C, and the time is 1-10h.

[0017] Beneficial effects of the present invention:

[0018] (1) The present invention obtains diaspore catalyst by etching amorphous aluminum hydroxide. An aluminum salt solution is mixed with a precipitant to obtain aluminum hydroxide gel, which is then hydrothermally heated, washed, and dried to obtain amorphous aluminum hydroxide. The aluminum hydroxide is subjected to organic alkali etching treatment, and macromolecular organic functional groups are adsorbed near the Al ions to prevent the loss of Al ions. Strong alkaline groups act on the hydroxyl groups of the aluminum hydroxide to promote dehydration. Some hydroxyl groups of the aluminum hydroxide are retained and the coordination number of the Al atoms is reduced, thereby strengthening its surface alkalinity. A large number of hydroxyl groups on the surface act as Bronsted bases and promote the activation of α-H bonds in cyclopropyl methyl ketone. A structurally stable diaspore can be formed through the chemical precipitation-hydrothermal-alkali etching process, which prevents the catalyst from undergoing structural changes during the reaction and maintains stable catalytic activity.

[0019] (2) The diaspore catalyst prepared by the present invention has a hydroxyl-rich structure, providing a large number of basic sites. The catalyst structure is stable and suitable for multiple recycling and large-scale industrial application.

[0020] (3) The efficiency and circulation activity of the self-condensation of cyclopropyl methyl ketone to ketene catalyzed by the diaspore prepared in the present invention are significantly improved. In a condensation reflux reactor, tests show that the ketene selectivity reaches up to 92% and the conversion rate reaches up to 55%. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is the reaction route for preparing Syntin from 1,3-dicyclopropyl-2-butene-1-one.

[0023] Figure 2 This is an activity diagram of the diaspore catalyst prepared in the present invention under different temperature conditions.

[0024] Figure 3 Activity graph of the boehmite catalyst prepared in the present application under different catalyst dosage conditions.

[0025] Figure 4 Activity graph of the boehmite catalyst prepared in the present application under different reaction time conditions.

[0026] Figure 5 Cycle activity graph of the boehmite catalyst prepared in the present application.

[0027] Figure 6 XRD graph of the boehmite catalyst prepared in the present application.

[0028] Figure 7 FTIR graph of the boehmite catalyst prepared in the present application.

[0029] Figure 8 CO2-TPD graph of the boehmite catalyst prepared in the present application.

[0030] Figure 9 Activity graph of the activated alumina catalyst prepared in Comparative Example 1.

[0031] Figure 10 Activity graph of the KOH-modified aluminum hydroxide prepared in Comparative Example 2. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those of ordinary skill in the art without any creative effort belong to the protection scope of the present application.

[0033] Example 1

[0034] A preparation method of a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps:

[0035] Dissolve 1 g of aluminum nitrate hydrate (4.695 mmol) into water to prepare a 0.08 mol / L solution, add 2 mL of 30 wt% ammonia water, stir for 30 min, then continue to add 0.02 g of ammonium fluoride powder and stir for another 30 min to obtain an aluminum hydroxide gel. Move the gel into an autoclave and react in an oven at 180℃ for 4 h. After natural cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2 g of aluminum hydroxide into 20 mL of tetramethylammonium hydroxide for alkali etching treatment, stir vigorously for 0.5 h, then wash, dry and grind to obtain a boehmite catalyst.

[0036] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst with cyclopropyl methyl ketone at a mass ratio of 5% and reacting in an oil bath at 160° C. for 5 hours.

[0037] Example 2

[0038] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0039] Dissolve 1g of hydrated aluminum nitrate (4.695mmol) in water to form a 0.08mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30min. Then, add 0.02g of sodium fluoroborate powder and continue stirring for 30min to obtain aluminum hydroxide gel. Transfer the gel to a hydrothermal kettle and react in an oven at 180℃ for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetramethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0040] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst with cyclopropyl methyl ketone at a mass ratio of 5% and reacting in an oil bath at 160° C. for 5 hours.

[0041] Example 3

[0042] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0043] Dissolve 1g of hydrated aluminum nitrate (4.695mmol) in water to form a 0.08mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30min. Then, add 0.02g of sodium fluoroborate powder and continue stirring for 30min to obtain aluminum hydroxide gel. Transfer the gel to a hydrothermal kettle and react in a 160℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetramethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0044] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst with cyclopropyl methyl ketone at a mass ratio of 5% and reacting in an oil bath at 140° C. for 5 hours.

[0045] Example 4

[0046] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0047] Dissolve 1g of hydrated aluminum nitrate (4.695mmol) in water to form a 0.08mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30min. Then, add 0.02g of sodium fluoroborate powder and continue stirring for 30min to obtain aluminum hydroxide gel. Transfer the gel to a hydrothermal kettle and react in a 160℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetramethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0048] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst with cyclopropyl methyl ketone at a mass ratio of 8% and reacting in an oil bath at 120° C. for 5 hours.

[0049] Example 5

[0050] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0051] Dissolve 1g of hydrated aluminum nitrate (4.695mmol) in water to form a 0.08mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30min. Then add 0.03g of ammonium fluoride powder and continue stirring for 30min to obtain aluminum hydroxide gel. Move the gel into a hydrothermal kettle and react in a 140℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. Under room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetramethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0052] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst with cyclopropyl methyl ketone at a mass ratio of 5% and reacting in an oil bath at 120° C. for 8 hours.

[0053] Example 6

[0054] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0055] Dissolve 1g of aluminum sulfate 18hydrate (1.5mmol) in water to form a 0.05mol / L solution, add 2mL of 30wt% ammonia water and stir for 30min, then continue to add 0.05g of ammonium fluoride powder and continue stirring for 30min to obtain aluminum hydroxide gel. Move the gel into a hydrothermal kettle and react in a 160℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. Under room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetramethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0056] The above-mentioned diaspore catalyst and cyclopropyl methyl ketone were mixed in a mass ratio of 10%, and reacted in an oil bath at 100° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0057] Example 7

[0058] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0059] Dissolve 1g of aluminum chloride (7.499mmol) in water to make a 0.05mol / L solution, add 2mL of 30wt% ammonia water and stir for 30min, then add 0.05g of ammonium fluoride powder and continue stirring for 30min to obtain aluminum hydroxide gel. Move the gel into a hydrothermal kettle and react in a 120℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetraethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0060] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst and cyclopropyl methyl ketone in a mass ratio of 10% and reacting them in an oil bath at 130° C. for 6 hours.

[0061] Example 8

[0062] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0063] Dissolve 1g of aluminum sulfate 18hydrate (1.5mmol) in water to form a 0.05mol / L solution, add 2mL of 30wt% ammonia water and stir for 30min, then continue to add 0.05g of sodium fluoroborate powder and continue stirring for 30min to obtain aluminum hydroxide gel. Move the gel into a hydrothermal kettle and react in a 160℃ oven for 4h. After naturally cooling to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. Under room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetrabutylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0064] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst and cyclopropyl methyl ketone in a mass ratio of 12%, and reacting them in an oil bath at 120° C. for 10 hours.

[0065] Example 9

[0066] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps:

[0067] Dissolve 1g of aluminum acetate (4.899mmol) in water to make a 0.02mol / L solution, add 2mL of 30wt% ammonia water and stir for 30min, then add 0.05g of ammonium fluoride powder and continue stirring for 30min to obtain aluminum hydroxide gel. Move the gel into a hydrothermal kettle and react in a 120℃ oven for 4h. After cooling naturally to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. At room temperature, slowly add 2g of aluminum hydroxide to 20mL of tetraethylammonium hydroxide for alkaline etching. After vigorously stirring for 0.5h, wash, dry and grind to obtain diaspore catalyst.

[0068] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the above-mentioned diaspore catalyst and cyclopropyl methyl ketone in a mass ratio of 15% and reacting them in an oil bath at 110° C. for 8 hours.

[0069] Example 10

[0070] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 10%, and reacting the mixture in an oil bath at 90° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0071] Example 11

[0072] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 10%, and reacting the mixture in an oil bath at 100° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0073] Example 12

[0074] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 10%, and reacting the mixture in an oil bath at 120° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0075] Example 13

[0076] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 10%, and reacting the mixture in an oil bath at 130° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0077] Example 14

[0078] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 10%, and reacting the mixture in an oil bath at 140° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0079] Figure 2 The activity of the diaspore catalysts in Examples 9-14 at different temperatures is shown. Catalyst performance was evaluated within the 90-140°C range, with other temperature adjustments remaining consistent. With increasing temperature, the conversion of cyclopropyl methyl ketone increases, attributed to molecular collisions and increased product desorption. Rapid collisions and desorption between reactant molecules and the catalyst's active sites conform to thermodynamic principles. The selectivity for ketene decreases with increasing temperature, attributed to the formation of polymeric products. The C=O bond of the ketene continues to be activated by the active sites, undergoing a condensation reaction with the protonated cyclopropyl methyl ketone.

[0080] Example 15

[0081] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 1%, and reacting the mixture in an oil bath at 120° C. for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0082] Example 16

[0083] A method for preparing a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone according to a mass ratio of 5%, and obtaining the target product 1,3-dicyclopropyl-2-buten-1-one after 8 hours of reaction in a 120°C oil bath.

[0084] Example 17

[0085] A method for preparing a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone according to a mass ratio of 8%, and obtaining the target product 1,3-dicyclopropyl-2-buten-1-one after 8 hours of reaction in a 120°C oil bath.

[0086] Example 18

[0087] A method for preparing a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone according to a mass ratio of 12%, and obtaining the target product 1,3-dicyclopropyl-2-buten-1-one after 8 hours of reaction in a 120°C oil bath.

[0088] Example 19

[0089] A method for preparing a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone according to a mass ratio of 15%, and obtaining the target product 1,3-dicyclopropyl-2-buten-1-one after 8 hours of reaction in a 120°C oil bath.

[0090] Figure 3 A graph of the activity of the diaspore catalyst in Examples 15-19 under different catalyst dosages. As the catalyst dosage increases, the number of active sites increases, the conversion rate of cyclopropyl methyl ketone increases, which is attributed to the increase in intermolecular collision efficiency. The decrease in enone selectivity is attributed to the timely desorption of enone after adsorption saturation, which leads to continuous reaction with cyclopropyl methyl ketone.

[0091] Example 20

[0092] A method for preparing a 1,3-dicyclopropyl-2-buten-1-one compound, comprising the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone according to a mass ratio of 12%, and obtaining the target product 1,3-dicyclopropyl-2-buten-1-one after 4 hours of reaction in a 120°C oil bath.

[0093] Example 21

[0094] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 12%, and reacting the mixture in an oil bath at 120° C. for 6 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0095] Example 22

[0096] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 12%, and reacting the mixture in an oil bath at 120° C. for 10 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0097] Example 23

[0098] A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound comprises the following steps: mixing the diaspore catalyst prepared in Example 9 with cyclopropyl methyl ketone in a mass ratio of 12%, and reacting the mixture in an oil bath at 120°C for 12 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0099] Figure 4 Figure 2 is the activity diagram of the diaspore catalyst under different reaction times in Examples 18 and 20-23. The activity of the catalyst in 4-12h was investigated. The catalytic activity increased gradually in 4-10h and then approached stability. The reaction of cyclopropyl methyl ketone dehydration to synthesize ketene is reversible. After a period of reaction, the positive reaction approaches equilibrium, so the yield no longer increases over time. Since the abundant hydroxyl groups on the catalyst surface produce stronger alkaline active sites, the catalytic efficiency is higher, so extending the reaction time causes side reactions (polymeric compounds) to occur.

[0100] To further explore the stability of the diaspore catalyst, the diaspore catalyst prepared in Example 9 was mixed with cyclopropyl methyl ketone at a mass ratio of 10%. After reacting in an oil bath at 120°C for 8 hours, the target product 1,3-dicyclopropyl-2-butene-1-one was obtained. The diaspore catalyst was then filtered out and washed, and the above experiment was repeated as a catalyst. The results are shown in Figure 2. Figure 5 As shown in the figure, the conversion rate and product selectivity of the catalyst hardly decreased after 5 cycles, indicating that it has good stability.

[0101] Comparative Example 1

[0102] An active Al2O3 catalyst, the preparation method comprises the following steps:

[0103] Dissolve 1g of aluminum sulfate 18hydrate (1.5mmol) in water to make a 0.05mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30 minutes. Then, add 0.05g of sodium borofluoride powder and continue stirring for 30 minutes to obtain an aluminum hydroxide gel. The gel is transferred to a hydrothermal reactor and reacted in a 160°C oven for 4 hours. After cooling naturally to room temperature, it is washed, dried, and ground to obtain aluminum hydroxide powder. The aluminum hydroxide powder is calcined in a vacuum atmosphere to obtain an active Al2O3 catalyst.

[0104] The active Al2O3 catalyst and cyclopropyl methyl ketone were mixed at a mass ratio of 10%, and the mixture was reacted in an oil bath at 120°C for 8 hours to obtain the target product 1,3-dicyclopropyl-2-butene-1-one.

[0105] Comparative Example 2

[0106] A catalyst for inorganic base-modified aluminum hydroxide, the preparation method of which comprises the following steps:

[0107] Dissolve 1g of aluminum sulfate 18hydrate (1.5mmol) in water to make a 0.05mol / L solution. Add 2mL of 30wt% ammonia water and stir for 30min. Then add 0.05g of sodium borofluoride powder and continue stirring for 30min to obtain aluminum hydroxide gel. Transfer the gel to a hydrothermal kettle and react in a 160℃ oven for 4h. After cooling naturally to room temperature, wash, dry and grind to obtain aluminum hydroxide powder. Dissolve 1.2g of aluminum hydroxide powder in 0.1mol / L KOH solution and stir for 3h. After washing and drying, obtain an inorganic base-modified aluminum hydroxide catalyst.

[0108] The target product 1,3-dicyclopropyl-2-butene-1-one was obtained by mixing the inorganic base-modified aluminum hydroxide catalyst and cyclopropyl methyl ketone at a mass ratio of 10% and reacting them in an oil bath at 120° C. for 8 hours.

[0109] The diaspore catalyst prepared in Example 9 and the Al2O3 catalyst prepared in Comparative Example 1 were characterized. Figure 6-8 As stated. Figure 6 This is the XRD pattern of the diaspore catalyst prepared in Example 9. The diffraction peaks at 14.5°, 28.2°, 38.4°, 49.3°, 66.9°, 67.7°, and 68.5° are attributed to the (020), (120), (031), (200), (022), (171), and (260) crystal planes of AlO(OH), respectively, corresponding to standard card PDF No. 83-2384. The unit cell structure is orthorhombic, with space group Amam(63) and unit cell dimensions of 3.6936*12.214*2.8679. The diffraction peaks are slightly spread out, which is attributed to the small crystal size.

[0110] Figure 7 This is the FTIR spectrum of the diaspore catalyst prepared in Example 9. Located at 3200-3500 cm -1 The characteristic peaks are attributed to surface hydroxyl groups, which are the key to the formation of B acid sites. Compared with activated alumina, the diaspore prepared by etching has a stronger hydroxyl signal peak, proving that it is more basic.

[0111] Figure 8 This is the CO2-TPD graph of the diaspore catalyst prepared in Example 9. The desorption peak at 50-150°C is attributed to physically adsorbed CO2. The desorption peak at 300-420°C is attributed to the chemical adsorption formed by the surface hydroxyl groups of diaspore and CO2. The desorption peak at 420-500°C is attributed to the characteristic peak formed by the adsorption of CO2 on the basic sites formed by lattice oxygen. It is noted that the alkalinity is significantly improved due to the large number of hydroxyl groups bonded to the surface of diaspore. Compared with activated alumina that relies on a small amount of hydroxyl groups adsorbed on the surface, the etching method can significantly improve the alkalinity of the catalyst surface.

[0112] Figure 9 The activity diagram of the catalysts in Comparative Example 1 and Example 13 shows that the conversion rate using the diaspore catalyst is 45%, which is 6.4 times that of the activated alumina.

[0113] Figure 10 The activity diagram of the catalysts in Comparative Example 2 and Example 13 shows that the conversion rate using the diaspore catalyst is 45%, which is 3.7 times that of the inorganic base-modified aluminum hydroxide.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a 1,3-dicyclopropyl-2-butene-1-one compound, characterized in that: Cyclopropyl methyl ketone and diaspore catalyst are mixed to carry out condensation reaction to generate 1,3-dicyclopropyl-2-butene-1-one.

2. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 1, characterized in that: The preparation method of the diaspore catalyst comprises: dissolving aluminum salt in water to prepare an aluminum salt solution, adding a precipitant and a morphology control agent to obtain aluminum hydroxide gel; subjecting the aluminum hydroxide gel to a hydrothermal reaction, washing, drying and grinding to obtain aluminum hydroxide powder; and subjecting the precursor to an alkali etching treatment, washing and drying, to obtain the diaspore catalyst.

3. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 2, wherein: The aluminum salt is any one of aluminum sulfate 18hydrate, hydrated aluminum nitrate, aluminum chloride, and aluminum acetate; and the concentration of the aluminum salt solution is 0.01-0.1 mol / L.

4. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 3, characterized in that: The precipitant is ammonia water, and the molar ratio of ammonia monohydrate to aluminum salt in the ammonia water is not greater than 1.

5. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 4, characterized in that: The morphology control agent is ammonium fluoride or sodium borofluoride; the mass ratio of the morphology control agent to the aluminum salt is 0.01-0.1:

1.

6. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 5, characterized in that: The temperature of the hydrothermal reaction is 110-180° C., and the time is 4 hours.

7. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 6, characterized in that: The alkaline etching treatment comprises the following steps: adding aluminum hydroxide powder into an alkaline solution for etching.

8. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 7, characterized in that: The alkali in the alkaline solution is an organic base; the organic base is any one of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrabutylammonium hydroxide.

9. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to claim 8, characterized in that: The concentration of the alkaline solution is 10%-25wt%; the etching time is 0.5-3h.

10. The method for preparing 1,3-dicyclopropyl-2-butene-1-one compound according to any one of claims 1 to 9, characterized in that: The addition amount of the diaspore catalyst is 1-15 wt% of the cyclopropyl methyl ketone; the temperature of the condensation reaction is 90-160° C., and the time is 1-10 hours.

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