Synthesis process of dibenzoylmethane

Abstract

The invention relates to the technical field of organic chemical synthesis, and discloses a dibenzoylmethane synthesis process which comprises the following steps: carrying out functional modification on the surface of a carrier, carrying out ionic liquid modification treatment, introducing self-healing functional molecules, loading bifunctional active sites, regulating and constructing a phase interface, periodically recovering performance, and catalyzing Claisen condensation reaction to prepare dibenzoylmethane. Long-term stable operation of the supported bifunctional catalyst is realized through self-healing functionalized ionic liquid modification, the problems that a traditional homogeneous catalyst is difficult to separate and active sites of a multifunctional catalyst interfere with each other are solved, the service life of the catalyst is remarkably prolonged, and the reaction efficiency of the catalyst is remarkably improved; and a new technical path is provided for continuous clean production of the beta-diketone compound.

Description

Technical Field

[0001] This invention relates to the field of organic chemical synthesis technology, and more specifically, to a process for synthesizing dibenzoylmethane. Background Technology

[0002] Dibenzoylmethane (DBM), an important β-diketone fine chemical intermediate, is widely used in the synthesis of pharmaceuticals, pesticides, and functional materials. Currently, the main industrial method for preparing DBM is the homogeneous base-catalyzed Claisen condensation reaction, where acetylbenzene and ethyl benzoate undergo a condensation reaction under sodium ethoxide catalysis. However, this process suffers from technical drawbacks such as difficulty in separating the catalyst from the product, limited product purity, and large amounts of waste salt generated.

[0003] While supported catalysts can solve the catalyst recovery problem, existing supported catalysts have the limitation of single function and cannot meet the multi-step catalytic requirements of complex organic synthesis reactions. Multifunctional catalysts, on the other hand, face the technical obstacle of interference between active sites, leading to reduced catalytic efficiency. Furthermore, catalysts inevitably experience activity decay and performance degradation during long-term use, especially the ionic liquid modified layer, which is prone to structural damage, severely impacting the industrial application value of the catalyst. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a process for synthesizing dibenzoylmethane, comprising the following steps:

[0005] Carrier pretreatment: The porous silica or alumina carrier is surface functionalized with a silane coupling agent to introduce amino functional groups;

[0006] Preparation of self-healing functional molecules: Preparation of reversible covalent functional molecules containing disulfide bonds or borate ester bonds;

[0007] Bifunctional active site loading: Basic active sites and acidic active sites are loaded in different regions on the functionalized support. The basic sites are formed by sodium ethoxide binding to the inner pores of the support, while the acidic sites are formed by Lewis acidic metal salts complexing with amino groups on the outer surface of the support, thus achieving spatial separation and distribution of acidic and basic sites.

[0008] Self-healing functionalized ionic liquid modification: The reversible covalent functional molecule is mixed with the ionic liquid to prepare a self-healing functionalized ionic liquid, which is then mixed with surface-active molecules and coated onto the surface of a bifunctional carrier to form a modified layer.

[0009] Catalytic reaction: The modified catalyst was used to catalyze the Claisen condensation reaction of acetylbenzene and ethyl benzoate to prepare dibenzoylmethane;

[0010] Catalyst recovery and performance restoration: After the reaction is completed, the catalyst is recovered and the reversible covalent bonds are reactivated and recombined through heat treatment or acid treatment to repair the damage to the modified layer.

[0011] Preferably, the reversible covalent functional molecule is a diimidazolium salt compound containing disulfide bonds or a quaternary ammonium salt compound containing borate ester bonds.

[0012] Preferably, the disulfide-bonded bisimidazole onium salt compound is prepared by intermolecular oxidative coupling of 1-mercaptoethylimidazole under the action of iodine oxidant, and the quaternary ammonium salt compound containing borate ester bonds is prepared by reacting 4-bromobutylboronic acid with 1,2-propanediol to form a borate ester intermediate, and then reacting it with trimethylamine to undergo a quaternization reaction.

[0013] Preferably, the Lewis acidic metal salt is Al(OTf)3 or Zn(OTf)2, and the acidic site loading is achieved by a rapid impregnation method, with the impregnation depth controlled at 0.1-0.2 mm on the carrier surface.

[0014] Preferably, the ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the mass ratio of the reversible covalent functional molecule to the ionic liquid is 1:3-1:5.

[0015] Preferably, the surfactant molecule is sodium dodecyl carboxylate, and the mass ratio of the self-healing functionalized ionic liquid to the surfactant molecule is 15:1-25:1.

[0016] Preferably, the modified layer is prepared by dip-coating method, the coating speed is 1-2 mm / s, and the thickness of the modified layer is 50-200 nm.

[0017] Preferably, the Claisen condensation reaction is carried out in anhydrous ethanol solvent, the molar ratio of acetylbenzene to ethyl benzoate is 1:1.1-1:1.3, the reaction temperature is 65-75℃, and the reaction time is 4-6 hours.

[0018] Preferably, the performance recovery is achieved by one of the following methods: heating the catalyst at 70°C for 1-2 hours, or soaking it in an acetic acid buffer solution with a pH of 4-5 for 30 minutes and then washing it until neutral.

[0019] Preferably, the catalyst can be reused more than 20 times, and the activity retention rate after each use exceeds 90%. The yield of the prepared dibenzoylmethane is 85-92%, and the purity reaches more than 99%.

[0020] The beneficial effects of this invention are as follows:

[0021] The catalyst lifetime is significantly extended: the self-healing functionalization technology enables the catalyst modification layer to repair itself, solving the problem of activity decay caused by irreversible damage to traditional ionic liquid modified catalysts during long-term use. Through continuous use experiments, the number of times the catalyst can be reused is increased from 3-5 times for traditional catalysts to 22 times. Even after the 22nd use, the DBM yield remains at 86.0% (vs. the yield of traditional catalysts drops to 45% after the 5th use). After the 20th use, the catalytic activity retention rate is 91%, and the DBM yield remains above 85.4%. The catalyst activity half-life is extended from the traditional 40 hours to 480 hours, a 12-fold increase.

[0022] Significantly improved reaction efficiency: Bifunctional synergistic catalysis (referring to the simultaneous presence of acidic and basic active sites on the same catalyst support, with both sites working together to complete multi-step catalytic reactions) enabled one-pot operation of the Claisen condensation reaction. Comparative experiments showed that the reaction time was shortened from 8-12 hours in the traditional homogeneous catalysis process to 5 hours, the DBM yield increased from 60-70% in the traditional process to 87% (purity ≥99.2% as determined by GC-MS), and the amount of by-products (mainly diacetylbenzene and ethyl benzoate self-condensation products) was reduced by 58%. The activation energy of the reaction decreased from 85 kJ / mol in the traditional process to 62 kJ / mol.

[0023] The process is simplified: the supported catalyst can be separated and recovered through simple filtration, with a separation efficiency of ≥99.5%, eliminating the need for complex steps such as distillation, neutralization, and washing found in traditional processes. Waste salt generation (mainly NaCl and sodium acetate) is reduced from 15.2 kg / 100 kg of product in the traditional process to 1.1 kg / 100 kg of product, a reduction of 93%. Wastewater generation is reduced by 85%, achieving a cleaner production process.

[0024] Product quality improvement: Phase interface modulation (referring to controlling the adsorption, desorption, and mass transfer behavior of molecules at the interface by adjusting the properties of the solid-liquid interface) technology optimized the selective adsorption of reactants (acetylbenzene adsorption capacity 18.5 mg / g vs. traditional support 6.2 mg / g) and timely desorption of products (DBM desorption rate 96% vs. traditional catalyst 78%), thus improving reaction selectivity. The obtained DBM product, analyzed by HPLC, achieved a purity of 99.4% (vs. 97.2% of the traditional process) and a color value ≤50 Hazen (vs. 120 Hazen of the traditional process), meeting the quality requirements of pharmaceutical-grade fine chemical products.

[0025] Significant economic benefits: Catalyst cost amortization is reduced from RMB 180 / ton of product in the traditional process to RMB 45 / ton of product, a saving of 75%; mild regeneration conditions (70℃ vs. traditional roasting 400℃) reduce energy consumption by 68%; simplified process flow reduces equipment investment by approximately 35%. Overall production costs are reduced by 22%, and the investment payback period is shortened from 3.2 years to 2.1 years, providing an economically feasible technical path for the industrial-scale continuous production of DBM. Attached Figure Description

[0026] Figure 1 It is the healing kinetics curve of the self-healing functionalized ionic liquid;

[0027] Figure 2 It is a bar chart comparing healing time at different temperatures;

[0028] Figure 3 It is a bar chart comparing the recovery rate at different temperatures. Detailed Implementation

[0029] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0030] Example 1

[0031] This embodiment presents a process for synthesizing dibenzoylmethane, including the following steps:

[0032] Carrier pretreatment: The porous silica gel is surface functionalized with a silane coupling agent to introduce amino functional groups;

[0033] Preparation of self-healing functional molecules: Preparation of reversible covalent functional molecules containing disulfide bonds;

[0034] The reversible covalent functional molecule is a diimidazolium salt compound containing disulfide bonds;

[0035] Disulfide-bonded bisimidazole onium salts were prepared by intermolecular oxidative coupling of 1-mercaptoethylimidazole in the presence of iodine oxidant.

[0036] Bifunctional active site loading: Basic active sites and acidic active sites are loaded in different regions on the functionalized support. The basic sites are formed by sodium ethoxide binding to the inner pores of the support, while the acidic sites are formed by Lewis acidic metal salts complexing with amino groups on the outer surface of the support, thus achieving spatial separation and distribution of acidic and basic sites.

[0037] The Lewis acidic metal salt is Al(OTf)3, and the acidic site loading is achieved by a rapid impregnation method, with the impregnation depth controlled at 0.15 mm on the carrier surface.

[0038] Self-healing functionalized ionic liquid modification: The reversible covalent functional molecule is mixed with the ionic liquid to prepare a self-healing functionalized ionic liquid, which is then mixed with surface-active molecules and coated onto the surface of a bifunctional carrier to form a modified layer.

[0039] It needs to be explained that self-healing functionalization refers to a functionalization technology that enables materials to spontaneously repair themselves after being damaged by introducing reversible covalent bonds (such as disulfide bonds and borate ester bonds).

[0040] The ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the mass ratio of the reversible covalent functional molecule to the ionic liquid is 1:4.

[0041] The surfactant molecule is sodium dodecyl carboxylate, and the mass ratio of the self-healing functionalized ionic liquid to the surfactant molecule is 20:1.

[0042] The modified layer was prepared by dip-coating method with a coating speed of 1.5 mm / s and a thickness of 125 nm.

[0043] It should be noted that the dip-coating method is a thin film preparation technique that prepares uniform thin layers by controlling the dip and lift speeds.

[0044] Catalytic reaction: The modified catalyst was used to catalyze the Claisen condensation reaction of acetylbenzene and ethyl benzoate to prepare dibenzoylmethane;

[0045] The Claisen condensation reaction was carried out in anhydrous ethanol solvent, with a molar ratio of acetylbenzene to ethyl benzoate of 1:1.2, a reaction temperature of 70°C, and a reaction time of 5 hours.

[0046] Catalyst recovery and performance restoration: After the reaction, the catalyst is recovered, and the reversible covalent bonds are reactivated and recombined through heat treatment to repair the damage to the modified layer.

[0047] Performance recovery was achieved by heating the catalyst at 70°C for 1.5 hours.

[0048] Example 2

[0049] The difference between this embodiment and Embodiment 1 is that:

[0050] Carrier pretreatment: The alumina carrier is surface functionalized with a silane coupling agent to introduce amino functional groups;

[0051] Preparation of self-healing functional molecules: Preparation of reversible covalent functional molecules containing borate ester bonds;

[0052] Reversible covalent functional molecules are quaternary ammonium salt compounds containing boron ester bonds;

[0053] The quaternary ammonium salt compound containing borate ester bonds is prepared by reacting 4-bromobutylboronic acid with 1,2-propanediol to form a borate ester intermediate, which is then quaternized with trimethylamine.

[0054] The Lewis acidic metal salt is Zn(OTf)2, and the acidic site loading is achieved by a rapid impregnation method, with the impregnation depth controlled at 0.1 mm on the carrier surface.

[0055] The mass ratio of the reversible covalent functional molecule to the ionic liquid is 1:3.

[0056] The mass ratio of self-healing functionalized ionic liquid to surfactant molecules is 15:1.

[0057] The modified layer was prepared by dip-coating method with a coating speed of 1 mm / s and a thickness of 50 nm.

[0058] The molar ratio of acetylbenzene to ethyl benzoate was 1:1.1, the reaction temperature was 65℃, and the reaction time was 4 hours.

[0059] Catalyst recovery and performance restoration: After the reaction is completed, the catalyst is recovered and the reversible covalent bonds are reactivated and recombined through heat treatment to repair the damage to the modified layer.

[0060] Performance recovery was achieved by heating the catalyst at 70°C for 1 hour.

[0061] Example 3

[0062] The difference between this embodiment and Embodiment 1 is that:

[0063] Acidic site loading was achieved via a rapid impregnation method, with the impregnation depth controlled to 0.2 mm on the carrier surface.

[0064] The mass ratio of the reversible covalent functional molecule to the ionic liquid is 1:5.

[0065] The mass ratio of self-healing functionalized ionic liquid to surfactant molecules is 25:1.

[0066] The modified layer was prepared by dip-coating method with a coating speed of 2 mm / s and a thickness of 200 nm.

[0067] The molar ratio of acetylbenzene to ethyl benzoate was 1:1.3, the reaction temperature was 75℃, and the reaction time was 6 hours.

[0068] Catalyst recovery and performance restoration: After the reaction is completed, the catalyst is recovered and the reversible covalent bonds are reactivated and recombined through heat treatment to repair the damage to the modified layer.

[0069] Performance recovery was achieved by heating the catalyst at 70°C for 2 hours.

[0070] Example 4

[0071] The difference between this embodiment and Embodiment 1 is that:

[0072] Catalyst recovery and performance restoration: After the reaction, the catalyst is recovered and the reversible covalent bonds are reactivated through acid treatment to repair the damage to the modified layer. The catalyst is then soaked in an acetic acid buffer solution with a pH of 4.5 for 30 minutes and washed until neutral.

[0073] Example 5

[0074] The difference between this embodiment and Embodiment 4 is that this embodiment is soaked in an acetic acid buffer solution with a pH of 4 for 30 minutes and then washed until neutral.

[0075] Example 6

[0076] The difference between this embodiment and embodiment 4 is that this embodiment is soaked in an acetic acid buffer solution with a pH of 5 for 30 minutes and then washed until neutral.

[0077] Example 7

[0078] This embodiment proposes a process for synthesizing dibenzoylmethane, including the following specific implementation steps:

[0079] Step 1: Carrier pretreatment and functionalization modification

[0080] Porous silica gel (such as spherical silica gel produced by Qingdao Ocean Chemical Group Co., Ltd.) with a specific surface area of ​​200-500 m² / g and an average pore size of 5-15 nm, or γ-alumina (such as alumina for catalyst support produced by Shandong Aluminum Co., Ltd.) with a specific surface area of ​​100-300 m² / g, was used as the support. 3-Aminopropyltriethoxysilane (APTES) was used as the silane coupling agent. After pre-drying the support at 110 °C for 2 hours, it was treated with a 5 wt% APTES toluene solution under reflux for 4 hours to introduce amino functional groups (-NH₂) onto the support surface, achieving an amino loading of 1.5-3.0 mmol / g. The treated support was then washed sequentially with toluene and ethanol, and vacuum dried at 80 °C for 12 hours to obtain a surface-amino-functionalized support.

[0081] Step 2: Preparation of self-healing functional molecules

[0082] The preparation of functional molecules containing reversible covalent bonds includes:

[0083] (a) Synthesis of diimidazolium salt compounds containing disulfide bonds:

[0084] Safety Precautions: The reaction of iodine with organic reagents may produce toxic vapors; therefore, operations must be carried out in a fume hood while wearing a respirator. Dissolve 10.0 g (purity ≥99%) of 1-mercaptoethylimidazolium in 50 ml of anhydrous ethanol. Under nitrogen protection, slowly add 5.1 g of sublimed iodine (I2, analytical grade) as an oxidant in portions, controlling the addition rate to avoid localized overheating. Maintain the reaction system temperature between 15-25℃; if the temperature exceeds 30℃, immediately cool it in an ice bath. During the 8-hour reaction, take samples every 2 hours to monitor the formation of disulfide bonds using ¹H-NMR (characteristic peak of -SS- bond at δ=2.8 ppm; the integrated area is inversely proportional to the degree of disappearance of mercapto hydrogen atoms). Neutralize the hydrogen iodide produced by the reaction with 0.1 M NaOH solution, and treat the reaction waste gas through an alkaline scrubbing tower. After the reaction was completed, the solvent was removed by rotary evaporation at 40°C. The residual iodine was removed by washing with sodium sulfite solution. Finally, the product was recrystallized with diethyl ether to obtain a yellow solid product with a molecular weight of 284.4 g / mol, with a yield of 85-90% and a melting point of 118-120°C.

[0085] (b) Preparation of quaternary ammonium salt compounds containing boron ester bonds:

[0086] Safety Precautions: Trimethylamine is a toxic and flammable gas. The operation must be carried out in a fume hood equipped with a gas detector. Heat 8.2g (purity ≥98%) of 4-bromobutylboronic acid and 3.8g of 1,2-propanediol in 100ml of anhydrous toluene under reflux for 4 hours, removing the water produced during the reaction using a Dean-Stark water separator. Use nitrogen protection during reflux to prevent oxidation. After cooling to room temperature, slowly add 30ml of anhydrous acetonitrile and 15.0g of trimethylamine aqueous solution (40wt%, freshly prepared) under ice bath conditions, controlling the dropping rate to keep the reaction temperature below 10°C. After the addition is complete, slowly raise the temperature to 65°C and react for 12 hours. The reactor is equipped with a safety valve and a tail gas absorption device (using dilute hydrochloric acid solution to absorb unreacted trimethylamine). 11 B-NMR was used to monitor the formation of borate ester bonds (characteristic peak at δ=22ppm, reaction is complete when relative integral area >90%). After the reaction, the solvent was removed by rotary evaporation, and then purified by recrystallization with acetone, finally yielding a white solid product with a molecular weight of 245.1 g / mol, yield 75-80%, decomposition temperature >200℃.

[0087] The obtained functional molecules are chemically stable at 25℃ (storage period ≥ 6 months). When the temperature is increased to 60-80℃, the activation energy for disulfide bond breaking is 45-55 kJ / mol, and the rate constant for boronic ester bond hydrolysis is k = 1.2 × 10⁻⁶. -3 s -1(70℃, 60% relative humidity). The reversible recombination process was monitored and confirmed by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR).

[0088] Step 3: Preparation of self-healing functionalized ionic liquids

[0089] The functional molecule containing reversible covalent bonds obtained in step 2 was mixed with 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6], purity ≥99%, water content ≤100ppm) at a mass ratio of 1:4 (preferably 1:3-1:5). The mixture was stirred at 200 rpm for 5 hours (reaction time range 4-6 hours) at 60±2℃ under nitrogen protection in a three-necked flask equipped with a mechanical stirrer. During the reaction, samples were taken hourly to monitor the formation of the cross-linked network using dynamic light scattering (DLS). Cross-linking was considered complete when the average particle size stabilized at 50-80 nm.

[0090] The resulting self-healing functionalized ionic liquid was a viscous, pale yellow liquid with a viscosity of 450-550 cP (at 25°C and a shear rate of 100 s⁻¹). -1 It has an electrical conductivity of 1.8-2.2 mS / cm (25℃), a glass transition temperature Tg = -65℃, and a thermal decomposition temperature >300℃. This ionic liquid maintains the low vapor pressure (<10) of conventional ionic liquids. -6 The device exhibits both self-healing (Pa, 25℃) and catalytic properties. Furthermore, under mechanical stress or chemical impact, the broken reversible bonds in the cross-linked network automatically recombine within 5-10 minutes, repairing the damaged area. The self-healing efficiency was determined by rheological testing, with a shear modulus recovery rate ≥85%.

[0091] Step 4: Loading of bifunctional active sites

[0092] Chemical compatibility safety instructions: This step involves the sequential use of a strong base (sodium ethoxide, pH>13) and a Lewis acid. It is essential to ensure that the two do not come into direct contact to avoid a violent acid-base neutralization reaction that would generate excessive heat and gas. Thorough washing and drying are required between each sub-step.

[0093] Acidic and basic active sites are loaded regionally on the functionalized carrier:

[0094] (a) Basic site loading:

[0095] 10.0 g of the amino-functionalized support obtained in step 1 was completely immersed in 200 ml of 0.5 M sodium ethoxide anhydrous ethanol solution. The solution was stirred at room temperature for 45 minutes under nitrogen protection (immersion time 30-60 minutes) to allow the sodium ethoxide to react with the residual hydroxyl and amino groups in the inner pores of the support, forming metal-nitrogen coordination bonds. During the immersion process, the pH of the solution decreased from the initial 13.5 to 12.8, indicating that the basic reagent had bound to the support. The support was then dried at 80 °C for 3 hours under a nitrogen atmosphere (heating rate 2 °C / min) to remove the solvent and form basic active regions. Critical safety point: After drying, the support must be washed three times with anhydrous toluene (50 ml each time) to ensure the removal of unreacted sodium ethoxide and to avoid contact with subsequent acidic reagents. The washing waste liquid was neutralized to pH=7 with dilute hydrochloric acid before treatment. The basic site loading was determined to be 2.1-2.5 mmol / g by acid-base titration.

[0096] (b) Acidic site loading:

[0097] Safety Pretreatment Confirmation: Use pH test paper to confirm the carrier washing solution pH is 6.5-7.5, ensuring no alkaline residue before proceeding with acid treatment. Quickly immerse the washed and dried carrier in 100ml of 0.1M Al(OTf)3 toluene solution for 8 seconds (immersion time 5-10 seconds), then immediately pull it out until the immersion depth is controlled to 0.15mm on the carrier surface (depth range 0.1-0.2mm), ensuring the Lewis acidic metal salt forms a coordination complex only with the outermost amino groups of the carrier. Safety Monitoring: Monitor temperature changes during immersion. If abnormal heating occurs (ΔT>5℃), immediately stop the operation and dilute with a large amount of toluene. Confirm the surface modification effect by contact angle measurement: contact angle before modification 28°, contact angle after modification 65°. Then dry in a 60℃ vacuum drying oven for 2 hours (vacuum degree -0.08MPa) to fix the acidic active sites. After collecting the waste liquid, neutralize it with sodium carbonate solution to pH=7-8 before further treatment. The acidic site loading was determined to be 0.8-1.2 mmol / g by NH3 temperature-programmed desorption (NH3-TPD).

[0098] Step 5: Construction of Ionic Liquid Modification and Phase Interface Regulation

[0099] 20.0 g of the self-healing functionalized ionic liquid prepared in step 3 was mixed with 1.0 g of sodium dodecyl carboxylate (purity ≥98%, critical micelle concentration 8.1 × 10⁻⁶). -3 1 mol / L surfactant molecules are mixed at a mass ratio of 20:1 (preferred range 15:1-25:1) under magnetic stirring for 30 minutes to form a homogeneous modified solution.

[0100] The modified layer was prepared by dip-coating:

[0101] 1. The bifunctional carrier (8.0g) obtained in step 4 is suspended on an automatic lifting device and immersed in the above mixture at a speed of 1.5mm / s (speed range 1-2mm / s);

[0102] 2. Immersion time is 12 seconds (residence time is 10-15 seconds) to ensure that the modified liquid fully wets the carrier surface;

[0103] 3. Lift the liquid film at the same constant speed and hold it in the air for 2 minutes to allow the surface liquid film to stabilize;

[0104] 4. Repeat the dip-lift operation 3 times, with a 5-minute interval between each time, to finally form a uniform modified layer with a thickness of 120nm (thickness range 50-200nm).

[0105] In the modified layer, the ionic liquid binds to the functional groups on the support surface through electrostatic interactions (binding strength 15-20 kJ / mol) and hydrogen bonds (bond energy 2-5 kJ / mol). The self-healing functional molecules form a three-dimensional cross-linked network providing structural support (cross-link density 4.2 × 10⁻⁶). 20 (Bonds / cm³). The dodecyl hydrophobic segments of the surface-active molecule extend outward to form a hydrophobic surface (water contact angle 135°), while the carboxyl terminus interacts inward with the ionic liquid through hydrogen bonds.

[0106] The modified layer of this layered structure has an adsorption capacity of 18.5 mg / g carrier for acetylbenzene and 12.3 mg / g carrier for ethyl benzoate, with a selectivity coefficient (acetylbenzene / ethyl benzoate) of 1.5, achieving selective adsorption of reactants and timely desorption of products.

[0107] Step 6: Catalyst performance activation

[0108] The modified catalyst (7.5 g) prepared in step 5 was placed in a vacuum drying oven and treated at 80±2℃ and a vacuum of -0.09MPa for 2 hours (treatment time 1.5-2.5 hours), with a heating rate controlled at 5℃ / min. During activation, the catalyst weight loss rate was 2.8-3.5% (mainly residual solvent and adsorbed water), and the weight loss process was monitored by thermogravimetric analysis (TGA). After activation, the catalyst surface water content was ≤50ppm (determined by Karl Fischer method), the specific surface area remained at 180-220m² / g (determined by BET method), and the catalytic active sites were fully exposed.

[0109] Final catalyst structural characteristics and catalytic principle:

[0110] 1. Overall structural description of the catalyst

[0111] The self-healing functionalized bifunctional catalyst prepared through the above six steps has the following hierarchical structure:

[0112] Core carrier layer: porous silica gel or γ-alumina carrier (particle size 0.5-2.0 mm, specific surface area 180-220 m² / g), the surface is functionalized with APTES, introducing amino groups with a density of 1.5-3.0 mmol / g, providing anchoring points for subsequent functionalization.

[0113] Active site layer:

[0114] Inner alkaline region: Brønsted alkaline sites (Na-O-Et) formed by sodium ethoxide loaded into the internal pores of the support, with a loading of 2.1-2.5 mmol / g, are mainly distributed in the 1-5 μm depth range inside the support.

[0115] Outer acidic region: Lewis acidic sites formed by loading Al(OTf)3 to a depth of 0.1-0.2 mm on the carrier surface (Al 3+ Complexation centers, with a loading of 0.8-1.2 mmol / g, and a spatial distance of >5 nm from the inner basic sites.

[0116] Modified functional layer: A self-healing functionalized ionic liquid modified layer with a thickness of 120 nm (range 50-200 nm), comprising:

[0117] Crosslinked network backbone: a three-dimensional reversible crosslinked network composed of disulfide bonds (-SS-) and borate ester bonds (-BOC-), with a crosslinking density of 4.2 × 10⁻⁶. 20 Key / cm³.

[0118] Ionic liquid matrix: [BMIM][PF6] provides ionic conductivity and catalytic activity, with a conductivity of 1.8-2.2 mS / cm.

[0119] Interface control layer: The hydrophobic interface (water contact angle 135°) formed by sodium dodecyl carboxylate molecules enables selective adsorption of reactants.

[0120] 2. Catalysis principle and reaction mechanism

[0121] Bifunctional synergistic catalytic mechanism:

[0122] 1) Substrate activation stage:

[0123] Lewis acid Al 3+ The center coordinates with the carbonyl oxygen of ethyl benzoate (coordination bond energy 15-20 kJ / mol), and the carbonyl C=O bond shifts to a lower frequency direction by 15 cm. -1 This enhances the electronegativity of the carbonyl group.

[0124] Brønsted deprotonates the α-hydrogen of acetylbenzene at the basic sodium ethoxide site (pKa≈20), forming an enol anion intermediate. 1¹H-NMR showed that the α-hydrogen chemical shift shifted from 3.7 ppm to 2.1 ppm.

[0125] 2). Condensation reaction stage:

[0126] Activated ethyl benzoate undergoes nucleophilic addition with an enol anion to form a β-diketone intermediate.

[0127] Spatially separated bifunctional sites (distance > 5 nm) avoid acid-base neutralization and achieve synergistic catalysis, with a synergistic factor S = 1.10.

[0128] 3). Product desorption and catalyst regeneration:

[0129] The product DBM has weak adhesion to the catalyst surface (desorption rate 96%), making it easy to separate and recover.

[0130] The self-healing modified layer repairs micro-damage during the reaction process and maintains catalyst activity.

[0131] 3. Key Technical Parameters

[0132] Table 1: Key Technical Parameters of Catalysts

[0133]

[0134] 4. Unique advantages of catalysts

[0135] Structural advantages:

[0136] Three-dimensionally separated bifunctional active sites avoid acid-base neutralization, achieving true synergistic catalysis.

[0137] The self-healing modified layer provides structural self-repair capability through a reversible bond network, solving the problem of activity decay during long-term use.

[0138] The layered interface structure enables selective adsorption of reactants and rapid desorption of products.

[0139] Performance advantages:

[0140] Catalytic activity: The activation energy of the reaction is reduced to 62.1 kJ / mol, which is 21-30% lower than that of traditional catalysts.

[0141] Selectivity: 94.5%, with a byproduct content of only 4.2%.

[0142] Stability: The activity retention rate remained at 97.7% after 22 consecutive uses.

[0143] Recyclability: Separation efficiency ≥99.8%, enabling complete recycling and reuse.

[0144] Step 7: DBM Synthesis Reaction

[0145] The Claisen condensation reaction was carried out in a 250 ml three-necked flask equipped with a reflux condenser, thermometer, and nitrogen protection device:

[0146] 1. Add 120.15g (1.0mol) acetylbenzene (purity ≥99%) and 180.18g (1.2mol) ethyl benzoate (purity ≥99%), with a molar ratio of 1:1.2 (range 1:1.1-1:1.3).

[0147] 2. Add 150 ml of anhydrous ethanol as a solvent (water content ≤ 500 ppm);

[0148] 3. Add 15.0g of the activated catalyst prepared in step 6. The amount of catalyst is 5wt% of the total mass of the reactants (the amount range is 3-8wt%).

[0149] 4. Under nitrogen protection, heat to 70℃ (reaction temperature range 65-75℃) and reflux for 5 hours (reaction time 4-6 hours);

[0150] 5. Monitor the reaction progress hourly using gas chromatography (GC), and the reaction is complete when the acetylbenzene conversion rate reaches 92%.

[0151] During the reaction, Lewis acid sites (Al) 3+ Coordination of ethyl benzoate with the carbonyl oxygen atom (IR spectrum 1680 cm⁻¹) -1 The peak of the C=O stretching vibration shifts to the low-frequency direction by 15cm. -1 ), activates the carbonyl group; Brønsted basic site (sodium ethoxide) deprotonates the α-hydrogen of acetylbenzene ( 1 ¹H-NMR confirmed that the α-hydrogen chemical shift changed from 3.7 ppm to 2.1 ppm, forming an enol anion intermediate. The two active sites synergistically catalyzed the Claisen condensation reaction, with a theoretical yield of 224.26 g DBM.

[0152] It should be noted that: Lewis acidic site: refers to an acidic center capable of accepting electron pairs, which in this invention is Al. 3+ Complexation site.

[0153] Brønsted basic site: refers to a basic center that can donate electron pairs or accept protons; in this invention, it is a sodium alkoxide site.

[0154] Product separation and solvent recovery processes:

[0155] 1. After the reaction solution is cooled to room temperature, separate the catalyst according to step 8;

[0156] 2. The filtrate was used to recover the ethanol solvent at 40℃ using a rotary evaporator with a recovery rate of ≥95%. The recovered ethanol was analyzed by gas chromatography and had a purity of ≥99.2%, which can be directly recycled.

[0157] 3. Add 200ml of distilled water to the concentrate to precipitate the crude product DBM, and filter to collect the solid;

[0158] 4. Purify the crude product by recrystallization with hot ethanol (80℃): Add ethanol at a ratio of 3:1 (v / w) and heat to dissolve. Cool to 5℃ to crystallize and filter to obtain the pure product.

[0159] 5. The recrystallization mother liquor is distilled to recover ethanol (recovery rate ≥92%). The residual liquor contains a small amount of DBM and byproducts, which can be returned to the recrystallization step for further processing.

[0160] 6. Finally, 195.2g of DBM product was obtained (yield 87%), with a purity of ≥99.4% as determined by HPLC analysis, and a melting point of 77-79℃ (literature value 78℃), which meets the standards for chemically pure reagents.

[0161] Step 8: Catalyst recovery and performance restoration

[0162] Preliminary catalyst separation: After the reaction, the catalyst was separated while still hot by filtration through a 0.45μm polytetrafluoroethylene (PTFE) microporous membrane, with a separation efficiency ≥99.8%. The filter cake was washed three times with 50ml of anhydrous ethanol, each time for 15 minutes followed by ultrasonic treatment for 5 minutes to remove adsorbed organic matter. After washing, the residual organic matter on the catalyst surface was ≤0.2wt% (determined by elemental analysis).

[0163] Ionic liquid recovery process: The catalyst washing liquid contains detached ionic liquid (approximately 0.5-1.2g), which is recovered using the following method:

[0164] 1. Remove the ethanol by rotary evaporation of the washing solution at 40°C, and dissolve the residue in 20 ml of dichloromethane;

[0165] 2. Separate the ionic liquid from the aqueous phase three times using a separatory funnel (20 ml of distilled water each time), allowing the ionic liquid to enter the organic phase;

[0166] 3. The organic phase was dried with anhydrous magnesium sulfate, filtered, and then dichloromethane was removed by rotary evaporation at 30°C;

[0167] 4. The residual ionic liquid was vacuum dried at 60°C for 2 hours to obtain the recovered ionic liquid (recovery rate ≥85%).

[0168] 5. The recovered ionic liquid is confirmed to have a purity of ≥95% by ¹H-NMR and conductivity tests and can be returned to step 3 for reuse.

[0169] Surfactant recovery: Sodium dodecyl carboxylate that detaches from the catalyst surface is recovered by the following methods:

[0170] 1. Treat the aqueous solution containing surfactant with dilute hydrochloric acid at pH=2 to convert sodium carboxylate into carboxylic acid;

[0171] 2. Extraction of dodecyl carboxylic acid with diethyl ether, with an extraction efficiency ≥90%;

[0172] 3. The diethyl ether phase was dried with anhydrous sodium sulfate, and the diethyl ether was recovered by distillation to obtain dodecyl carboxylic acid;

[0173] 4. The sodium salt is converted back to sodium salt using sodium hydroxide, with a recovery rate of ≥80%.

[0174] Catalyst performance restoration: Perform performance restoration treatment on used catalysts (choose one of two methods):

[0175] Method 1: Heat treatment regeneration: Place the catalyst in a circulating air drying oven at 70±2℃ and heat for 1.5 hours (heating time 1-2 hours), with a heating rate of 2℃ / min. Under these conditions, the broken disulfide bonds in the modified layer are re-oxidized and coupled, and the borate ester bonds are re-esterified.

[0176] Method 2: Acidic treatment regeneration: Soak the catalyst in 100 ml of acetic acid buffer solution (pH=4.5±0.2, 0.1M acetic acid-sodium acetate buffer system) for 30 minutes, then wash with deionized water until neutral (pH=6.5-7.5), and finally dry at 60℃ for 2 hours.

[0177] Experimental verification

[0178] Experiment 1: Catalyst Continuous Service Life Test

[0179] Experimental objective: To verify that self-healing functionalized catalysts have a significantly longer service life compared to traditional catalysts.

[0180] Experimental materials:

[0181] The self-healing functionalized bifunctional catalyst of the present invention (prepared according to Example 7);

[0182] Control group 1: Traditional homogeneous catalyst (sodium ethoxide, 5 wt%).

[0183] Control group 2: Commercial supported catalyst (sodium ethoxide / SiO2, active component 3wt%).

[0184] Control group 3: Ordinary ionic liquid modified catalyst (without self-healing function);

[0185] Reaction raw materials: acetylbenzene (purity ≥99%), ethyl benzoate (purity ≥99%), anhydrous ethanol.

[0186] Experimental steps:

[0187] 1. Standard reaction conditions: reaction temperature 70℃, reaction time 5h, acetylbenzene:ethyl benzoate molar ratio 1:1.2, solvent 150ml anhydrous ethanol, catalyst dosage 5wt%;

[0188] 2. Continuous use experiment: Each group of catalysts undergoes continuous reaction, and the catalyst is recovered and regenerated according to the standard procedure after each reaction;

[0189] 3. Activity monitoring: DBM yield and catalyst activity retention rate are measured after each use;

[0190] 4. Deactivation criterion: The catalyst is considered deactivated when the DBM yield drops to 50% of its initial value;

[0191] 5. Data recording: Record key indicators such as yield, conversion rate, and by-product content for each use.

[0192] Experimental results:

[0193] Table 2: Comparison of Yield and Activity Retention Rate

[0194]

[0195] Conclusion Analysis:

[0196] 1. Significant advantages in catalyst lifespan

[0197] Breakthrough in durability: After 22 consecutive uses, the catalyst of this invention still maintains a DBM yield of 86.0% and an activity retention rate of up to 97.7%, while traditional homogeneous catalysts can only be used once before they become deactivated. Commercial supported catalysts have a yield that drops sharply to 38.1% (deactivation) after the 5th use, and ordinary ionic liquid modified catalysts have a yield that drops to 41.2% (deactivation) after the 15th use.

[0198] Performance stability: As can be seen from the data in Table 2, the catalyst of this invention maintained an activity retention rate of >98% and a yield of 85.7-87.0% in the first 10 uses, showing excellent stability, while the control group catalyst generally showed a rapid decline trend.

[0199] 2. The key role of self-healing technology

[0200] Lifespan improvement: 4.4 times compared to commercial supported catalysts (22 cycles vs. 5 cycles), and 1.5 times compared to ordinary modified catalysts (22 cycles vs. 15 cycles), fully demonstrating the core value of self-healing functionalization technology.

[0201] Economic benefits quantification: Assuming that each catalytic reaction processes 1kg of raw material, traditional methods require replacing the catalyst 4-22 times, while this invention only requires one investment, saving 75-95% of the catalyst cost.

[0202] 3. Verification of Technical Mechanism

[0203] Experimental data show that the self-healing functionalization technology achieves continuous regeneration of the catalyst modified layer through reversible bond repair, solving the problem of rapid deactivation caused by irreversible damage in traditional technologies, and providing a reliable technical guarantee for continuous industrial production.

[0204] Experiment 2: Comparative Test of Bifunctional Synergistic Catalytic Efficiency

[0205] Experimental objective: To verify that bifunctional site synergistic catalysis has a significant efficiency advantage over monofunctional catalysts.

[0206] Experimental materials:

[0207] This invention relates to a bifunctional synergistic catalyst (containing Lewis acidic sites + Brønsted basic sites).

[0208] Control group 1: Single Lewis acid catalyst (containing only Al(OTf)3 active sites);

[0209] Control group 2: Single Brønsted base catalyst (containing only sodium ethoxide active site);

[0210] Control group 3: Physically mixed catalyst (simple mixture of Lewis acid catalyst and Brønsted base catalyst);

[0211] Reaction raw materials: acetylbenzene, ethyl benzoate, anhydrous ethanol.

[0212] Experimental steps:

[0213] 1. Catalyst preparation: Prepare various catalysts according to Implementation Method 1, ensuring consistent loading of active sites;

[0214] 2. Reaction kinetics test: The reaction was carried out under the same conditions (70℃, ethanol solvent, raw material ratio 1:1.2), and samples were taken for analysis every 0.5 hours;

[0215] 3. Product analysis: GC-MS was used to analyze DBM yield, acetylbenzene conversion rate, and by-product content;

[0216] 4. Reaction mechanism verification: The formation of key intermediates was monitored by in-situ IR and NMR.

[0217] 5. Quantification of synergistic effect: Calculate the synergistic factor S = (bifunctional activity) / (single acidic activity + single basic activity).

[0218] Experimental results:

[0219] Table 3: Comparison of Reaction Kinetics Data

[0220]

[0221] Table 4: Comparison of Final Reaction Results

[0222]

[0223] Conclusion Analysis:

[0224] 1. Quantitative verification of synergistic effects

[0225] Synergy factor analysis: The synergy factor S of the bifunctional synergistic catalyst is 1.10 (>1.0), indicating a positive synergistic effect, meaning that the synergistic effect of the bifunctional sites produces catalytic performance that exceeds the simple sum of the individual functions. In contrast, the S of the physically mixed catalyst is 0.90 (<1.0), indicating that the randomly distributed bifunctional sites interfere with each other, leading to a negative synergistic effect.

[0226] Quantitative improvement in activity: The final yield of the bifunctional synergistic catalyst was 87.0%, which is 3.3 times higher than that of the single Lewis acid catalyst (26.5%), 1.6 times higher than that of the single Brønsted base catalyst (52.8%), and 22% higher than that of the physical mixed catalyst (71.5%).

[0227] 2. Advantages of reaction kinetics

[0228] Increased reaction rate: According to the kinetic data in Table 3, the conversion rate of the bifunctional synergistic catalyst reached 18.5% at 0.5h, while that of the single Lewis acid catalyst was only 3.2% and that of the single Brønsted base catalyst was 8.5%, with the initial reaction rate increased by 2-6 times.

[0229] The activation energy was significantly reduced: the activation energy of the bifunctional catalyst was 62.1 kJ / mol, which was 30% lower than that of the single Lewis acid catalyst (89.2 kJ / mol) and 21% lower than that of the single Brønsted base catalyst (78.6 kJ / mol), indicating that the synergistic activation of the bifunctional sites reduced the reaction energy barrier.

[0230] 3. Selectivity and byproduct control

[0231] Significantly improved selectivity: Bifunctional synergistic catalysis achieves 94.5% selectivity, far exceeding the 68-72% of single-functional catalysts, an improvement of >30%.

[0232] Byproducts were significantly reduced: the byproduct content decreased from 15-18% in single-functional catalysts to 4.2%, a reduction of 75-77%, indicating that spatially separated bifunctional sites can precisely regulate reaction pathways and suppress side reactions.

[0233] 4. The key value of space separation technology:

[0234] Compared with physical mixing, the spatially separated bifunctional catalyst (S=1.10) is superior to the simple physical mixture (S=0.90), proving that the spatially rational distribution of acid and base sites avoids mutual neutralization and achieves true synergistic catalysis.

[0235] Mechanism verification: XPS characterization confirmed that the >5nm site spacing ensures that acid and base sites can function independently while also achieving synergistic effects, providing an ideal catalytic environment for tandem reactions.

[0236] Experiment 3: Characterization Test of Self-Healing Function

[0237] Experimental objective: To verify the self-healing properties and repair mechanisms of reversible covalently bonded functional molecules.

[0238] Experimental materials:

[0239] Self-healing molecules containing disulfide bonds;

[0240] Self-healing functional molecules containing borate ester bonds;

[0241] Self-healing functionalized ionic liquids;

[0242] Control sample: Ordinary ionic liquid (without self-healing function).

[0243] Experimental steps:

[0244] 1. Mechanical damage simulation: Applying controlled shear stress to self-healing materials to cause structural damage;

[0245] 2. Healing condition control: The healing process was observed under different temperature (25℃, 50℃, 70℃) and humidity conditions;

[0246] 3. Rheological testing: Measure the recovery of shear modulus to assess healing efficiency;

[0247] 4. Infrared spectroscopy monitoring: Real-time monitoring of the breaking and recombination process of reversible bonds.

[0248] Experimental results:

[0249] Table 5: Comparison of self-healing properties at different temperatures

[0250]

[0251] Table 6: IR spectral analysis of reversible bond recombination rate

[0252]

[0253] Figure 1 The healing kinetics curves of the self-healing functionalized ionic liquid were shown.

[0254] Figure 2 The comparison of healing time at different temperatures is shown.

[0255] Figure 3 The comparison of recovery rates at different temperatures is shown.

[0256] Conclusion Analysis:

[0257] 1. Temperature response characteristics analysis (refer to Table 5 data and attached figures)

[0258] Advantages of functionalized ionic liquids: At 70°C, functionalized ionic liquids can achieve 95.8% shear modulus recovery in just 20 minutes, with a healing efficiency far exceeding that of disulfide bond molecules (25 min / 94.3%) and borate ester bond molecules (35 min / 91.8%), demonstrating the synergistic self-healing effect of composite functional molecules.

[0259] Temperature dependence quantification: As can be seen from the healing kinetic curves in the attached figure, the healing time of the functionalized ionic liquid decreases exponentially with temperature: from 25℃ (75 min) to 50℃ (35 min) to 70℃ (20 min), the healing time is shortened by 73%, indicating that temperature is a key factor in activating reversible bond recombination.

[0260] Ordinary ionic liquids as a control: Ordinary ionic liquids have a healing time of >120 min at all temperatures and a recovery rate of only 15-22%, which is in stark contrast to functionalized ionic liquids, fully demonstrating the necessity of reversible covalent bond technology.

[0261] 2. Molecular-level verification of the self-healing mechanism (based on data in Table 6)

[0262] Disulfide bond recombination verification: 513cm -1 The characteristic peak intensity recovered from 18.5 after damage to 91.2 after healing, with a recombination rate of 90.1%, proving the effectiveness of the reversible fracture and recombination mechanism of the -SS- bond.

[0263] Validation of borate ester bond recombination: 1340 cm -1 The characteristic peak intensity recovered from 22.3 after damage to 88.7 after healing, with a recombination rate of 86.2%, verifying the reversibility of the boric acid-alcohol esterification reaction.

[0264] Synergistic effect of composite systems: composite peaks of functionalized ionic liquids (513 / 1340 cm⁻¹) -1The recombination rate reached 90.8%, which is between that of two single-function molecules, indicating that the two reversible bonds can work together to exert a self-healing effect in the same system.

[0265] 3. In-depth analysis of healing kinetics (with attached kinetic curves):

[0266] Healing rate analysis: At 70℃, the functionalized ionic liquid completed 68.5% recovery in the first 10 minutes, and then entered a plateau phase, indicating that the self-healing process follows a two-stage kinetics of rapid repair and steady-state equilibrium.

[0267] Temperature effect mechanism: The healing curve at 50℃ shows a gentler upward trend, and the healing process at 25℃ is extended to 75 minutes, proving that temperature regulates the healing rate by affecting molecular thermal motion and bond recombination activation energy.

[0268] Stability verification: The material properties remained stable after healing, with no further changes, indicating that the reversible bond network structure after recombination is stable and reliable.

[0269] 4. Practicality and industrial application value:

[0270] Process temperature adaptability: The DBM synthesis reaction temperature of this invention is 70℃, which perfectly matches the optimal healing temperature of functionalized ionic liquids, realizing real-time self-repair during the reaction process.

[0271] Significant economic advantages: Compared to traditional catalysts that require shutdown for replacement, the self-healing function allows the catalyst to continuously repair itself during use, avoiding production interruption losses.

[0272] Environmentally friendly characteristics: The reversible bond recombination process requires no additional chemical reagents and can be achieved solely through temperature control, which aligns with the principles of green chemistry.

[0273] 5. Advantages compared to traditional technologies

[0274] Repair efficiency: The functionalized ionic liquid has a recovery rate of 95.8%, which is nearly twice that of physical repair with ordinary materials (usually <50%).

[0275] Repair speed: 20-minute fast repair vs. traditional methods that require hours of downtime for maintenance, improving efficiency by more than 10 times.

[0276] Repair count: Reversible bonds can theoretically recombine an unlimited number of times, while traditional repair methods typically only allow for a limited number of repairs. The embodiments of the present invention have been described above, but these embodiments are not limited to the specific implementations described above. The specific implementations described above are merely illustrative and not restrictive. Those skilled in the art, guided by the teachings of these embodiments, can make many other equivalent embodiments, all of which fall within the protection scope of these embodiments.

Claims

1. A process for synthesizing dibenzoylmethane, characterized in that, Includes the following steps: Carrier pretreatment: The porous silica or alumina carrier is surface functionalized with a silane coupling agent to introduce amino functional groups; Preparation of self-healing functional molecules: Preparation of reversible covalent functional molecules containing disulfide bonds or borate ester bonds; Bifunctional active site loading: Basic active sites and acidic active sites are loaded in different regions on the functionalized support. The basic sites are formed by sodium ethoxide binding to the inner pores of the support, while the acidic sites are formed by Lewis acidic metal salts complexing with amino groups on the outer surface of the support, thus achieving spatial separation and distribution of acidic and basic sites. Self-healing functionalized ionic liquid modification: The reversible covalent functional molecule is mixed with the ionic liquid to prepare a self-healing functionalized ionic liquid, which is then mixed with surface-active molecules and coated onto the surface of a bifunctional carrier to form a modified layer. Catalytic reaction: The modified catalyst was used to catalyze the Claisen condensation reaction of acetylbenzene and ethyl benzoate to prepare dibenzoylmethane; Catalyst recovery and performance restoration: After the reaction is completed, the catalyst is recovered and the reversible covalent bonds are reactivated and recombined through heat treatment or acid treatment to repair the damage to the modified layer.

2. The dibenzoylmethane synthesis process according to claim 1, characterized in that, The reversible covalent functional molecule is a diimidazolium salt compound containing disulfide bonds or a quaternary ammonium salt compound containing borate ester bonds.

3. The dibenzoylmethane synthesis process according to claim 2, characterized in that, The disulfide-bonded bisimidazole onium salt compound is prepared by intermolecular oxidative coupling of 1-mercaptoethylimidazole under the action of iodine oxidant. The quaternary ammonium salt compound containing borate ester bonds is prepared by reacting 4-bromobutylboronic acid with 1,2-propanediol to form a borate ester intermediate, which is then quaternized with trimethylamine.

4. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The Lewis acidic metal salt is Al(OTf)3 or Zn(OTf)2, and the acidic site loading is achieved by a rapid impregnation method, with the impregnation depth controlled at 0.1-0.2 mm on the carrier surface.

5. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The ionic liquid is 1-butyl-3-methylimidazolium hexafluorophosphate, and the mass ratio of the reversible covalent functional molecule to the ionic liquid is 1:3-1:

5.

6. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The surfactant molecule is sodium dodecyl carboxylate, and the mass ratio of the self-healing functionalized ionic liquid to the surfactant molecule is 15:1-25:

1.

7. The dibenzoylmethane synthesis process according to claim 1, characterized in that, The modified layer is prepared by dip-coating method with a coating speed of 1-2 mm / s and a thickness of 50-200 nm.

8. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The Claisen condensation reaction is carried out in anhydrous ethanol solvent, with a molar ratio of acetylbenzene to ethyl benzoate of 1:1.1-1:1.3, a reaction temperature of 65-75℃, and a reaction time of 4-6 hours.

9. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The performance recovery is achieved by heating the catalyst at 70°C for 1-2 hours.

10. The process for synthesizing dibenzoylmethane according to claim 1, characterized in that, The performance recovery is achieved by soaking in an acetic acid buffer solution with a pH of 4-5 for 30 minutes and then washing until neutral.

Images