Composite catalyst and preparation method thereof and synthesis method of p-methoxycinnamate compounds

Abstract

The present invention provides a composite catalyst and a preparation method thereof and a synthesis method of p-methoxycinnamate compounds, wherein the composite catalyst includes a carrier modified by a modifier and a metal salt and a choline substance supported by the carrier. In the presence of the composite catalyst of the present invention, a Claison-Schmidt condensation reaction is catalyzed between aromatic aldehyde compounds and acetate compounds to obtain p-methoxycinnamate. The composite catalyst provided by the present invention has high reactivity and selectivity, a stable catalyst structure, and active ingredients are not easily lost, and the recycling of the catalyst can be achieved without frequent replacement of the catalyst. The operation is simple, and the operation is conducive to continuous industrial production, significantly improving equipment utilization. The use of the composite catalyst provided by the present invention can make the preparation of p-methoxycinnamate compounds react under relatively mild reaction conditions, without corrosion to the equipment, and without wastewater or waste salt generation, which is green and environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the field of organic synthesis, and particularly relates to a composite catalyst and a preparation method thereof, and a synthesis method of p-methoxycinnamate compounds. Background Art

[0002] Most p-methoxycinnamate esters, such as methyl p-methoxycinnamate, ethyl p-methoxycinnamate, isoamyl p-methoxycinnamate, and 2-ethylhexyl p-methoxycinnamate, are excellent absorbers in the UVB region, are non-irritating to the skin, and are safe, making them ideal sunscreens. They are commonly used in cosmetics, textiles, polymers, and other products. Among them, isoamyl p-methoxycinnamate and 2-ethylhexyl p-methoxycinnamate are the most commonly used.

[0003] Octylmethoxycinnamate, also known as OMC, is one of the most commonly used sunscreens in the world. It has an excellent UV absorption curve between 280 and 310 nm, high absorptivity, good safety, minimal toxicity, and excellent solubility in oily materials. Therefore, it is widely used in daily chemicals, plastics, rubber, coatings, and other fields. As an oil-soluble liquid UVB absorber, it can be compounded with various sunscreens.

[0004] Isoamyl p-methoxycinnamate, also known as IMC, is present in small quantities in the roots of Kaempferia galanga. Its synthetic counterpart is similar to its natural equivalent. It has good compatibility with common cosmetic ingredients, is easily biodegradable, and is environmentally compatible. It is commonly used in sunscreen products in EU countries.

[0005] Taking the synthesis of isooctyl p-methoxycinnamate as an example, there are many methods for the synthesis of isooctyl p-methoxycinnamate at home and abroad. According to the main raw materials, they can be mainly divided into the following four types: p-methoxystyrene method, p-methoxyaniline method, p-methoxyhalobenzene method and p-methoxybenzaldehyde method.

[0006] The Knoevenagel reaction uses p-methoxybenzaldehyde as a raw material to produce OMC. Using p-methoxybenzaldehyde and malonic acid and its derivatives as raw materials, under the action of a catalyst such as pyridine, p-methoxycinnamic acid is first produced. After the reaction is completed, the catalyst, piperidine, must be removed by acid washing. This operation undoubtedly produces a large amount of wastewater, which seriously pollutes the environment. OMC is then produced by esterification with isooctyl alcohol. However, malonic acid and its derivatives are relatively expensive, and the catalysts used, such as pyridine, have a strong odor and are highly toxic, which limits the feasibility of this method for industrial production.

[0007] OMC is prepared using p-methoxybenzaldehyde via the Clauson-Schmidt reaction: p-methoxybenzaldehyde and methyl acetate react using a strong base such as sodium methoxide as a catalyst. This is then acidified with hydrochloric acid or sulfuric acid to produce methyl p-methoxycinnamate. This is then transesterified with isooctyl alcohol in the presence of a catalyst such as sodium carbonate to produce OMC. After the reaction, the product must be washed with a large amount of water. This produces high-salt, high-COD wastewater, which places pressure on environmental protection treatment and pollutes the surrounding environment.

[0008] Alternatively, methyl acetate and isooctyl alcohol undergo an ester exchange reaction catalyzed by p-toluenesulfonic acid to produce isooctyl acetate. This is then condensed with p-methoxybenzaldehyde under the catalysis of liquid sodium methoxide to produce isooctyl p-methoxycinnamate. The amount of liquid sodium methoxide (at a concentration of 25-31%) is 25-65% by weight of the methoxybenzaldehyde used. After the condensation reaction, a fixed amount of glacial acetic acid is added to neutralize the remaining sodium methoxide in the reaction system. This reaction produces a large amount of sodium p-toluenesulfonate and sodium acetate waste salts, which not only poses a significant environmental burden but also makes the catalyst difficult to recycle and reuse, resulting in poor economic efficiency.

[0009] Therefore, in the prior art, the condensation method for preparing isooctyl p-methoxycinnamate from p-anisaldehyde and octyl acetate often uses sodium or potassium alcoholate as a catalyst, resulting in low yield, poor selectivity, numerous side reactions, inability to recycle the catalyst, and large amounts of wastewater. Therefore, there is considerable room for improvement. Therefore, it is necessary to adopt some effective strategies to increase the yield of p-methoxycinnamate esters, enable the reaction to proceed under mild reaction conditions, reduce wastewater and salt, and reduce production and environmental pressures. Summary of the Invention

[0010] In view of the deficiencies of the prior art, the object of the present invention is to provide a composite catalyst and a preparation method thereof, and a preparation method of p-methoxycinnamate compounds.

[0011] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0012] In one aspect, the present invention provides a composite catalyst comprising a carrier modified by a modifier and a metal salt and a choline substance supported by the carrier.

[0013] The composite catalyst of the present invention has high reaction activity and selectivity, a stable catalyst structure, and active components are not easily lost. The catalyst can be recycled without frequent catalyst replacement, is simple to operate, is conducive to continuous industrial production, and significantly improves equipment utilization. The composite catalyst can be used to catalyze the Clauson-Schmidt condensation reaction to prepare p-methoxycinnamate compounds, enables the reaction to proceed under relatively mild conditions, does not corrode equipment, and does not generate wastewater or waste salt, thereby being environmentally friendly.

[0014] Preferably, the modifying agent is an organosiloxane.

[0015] Preferably, the modifier is selected from one or a combination of at least two of vinyl pentamethyldisiloxane, hexaethyldisiloxane, 1,1,1,3,5,5,5-heptamethyltrisiloxane, polyphenylmethylsiloxane, polymethylhydrogensiloxane, hexamethyldisiloxane, hexamethoxydisiloxane, pentamethyldisiloxane, dodecamethylpentasiloxane, decamethyltetrasiloxane, hexamethylcyclotrisiloxane, octamethyltrisiloxane, and polydimethylsiloxane.

[0016] The organosiloxane can reduce the surface tension of the resin carrier, allowing good contact between the carrier and the active component, strengthening the bonding strength between the active component and the carrier, and inhibiting the agglomeration of the active component, thereby reducing the loss of the active component during the reaction, slowing down the deactivation of the catalyst, and realizing the recycling of the catalyst. The frequent replacement of the catalyst is no longer necessary, further reducing production costs.

[0017] Preferably, the carrier is a macroporous adsorption resin, preferably one or a combination of at least two of D3520, D141, S-8, HPD300, HZ801, XAD16N or DM11.

[0018] Preferably, the mass ratio of the modifier to the carrier is 1 to 5:1, for example, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1 or 5:1, etc., preferably 2 to 4:1.

[0019] Preferably, the mass ratio of the metal salt to the carrier is 0.01-0.09:1, for example, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1 or 0.09:1, preferably 0.03-0.07:1, more preferably 0.03-0.05:1.

[0020] Preferably, the metal salt is any one or a combination of at least two of zinc (Zn), iron (Fe), copper (Cu), cobalt (Co), nickel (Ni) hydrochloride or hydrates of the hydrochloride.

[0021] Preferably, the choline substance is one or a combination of at least two of choline chloride, β-methylcholine chloride, benzoylcholine chloride, butyrylcholine chloride, choline chloride, phosphorylcholine or acetylcholine chloride.

[0022] The choline-like substance and the active metal ion form a deep eutectic complex with properties similar to those of an ionic liquid through coordination bonds, while also possessing acid-base active centers, which play a synergistic catalytic role. Furthermore, the coordination-active oxygen atoms in the organosiloxane can coordinately bond with the active metal atoms to form a three-dimensional polynuclear metal complex with a defined molecular structure. These complexes possess porosity and low density, providing more highly active sites for the reaction and resulting in a catalyst with higher catalytic activity and selectivity.

[0023] Therefore, the macroporous resin support, modifier, active metal component, and choline-based substance in the catalyst provided by the present invention act synergistically, rather than as a sum of the effects of individual components. Therefore, the components of the catalyst of the present invention should not be viewed separately but as a complete whole, and not all random combinations will achieve optimal experimental results.

[0024] Preferably, the molar ratio of the metal salt to the choline substance is 1:1-5, for example, 1:1, 1:1.2, 1:1.5, 1:1.8, 1:2, 1:2.5, 1:2.8, 1:3, 1:3.5, 1:3.8, 1:4, 1:4.5, 1:4.8, 1:5, etc., preferably 1:1-4, more preferably 1:2-3.

[0025] On the other hand, the present invention provides a method for preparing the composite catalyst as described above, the preparation method comprising the following steps:

[0026] (1) The modifier and the carrier are mixed in a first solvent and reacted to obtain a carrier modified by the modifier;

[0027] (2) mixing the metal salt and the choline substance in a second solvent to obtain a mixed solution;

[0028] (3) Adding the carrier modified by the modifying agent obtained in step (1) to the mixed solution obtained in step (2), stirring, adsorbing, filtering, removing the solvent, and drying to obtain the composite catalyst.

[0029] Preferably, the reaction temperature in step (1) is 60°C to 120°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C or 120°C, preferably 80°C to 100°C.

[0030] Preferably, the reaction time in step (1) is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, preferably 2 to 3 hours.

[0031] Preferably, in step (1), the first solvent is selected from one or a combination of at least two of water, ethanol, methanol or isopropanol.

[0032] In step (1), the modifier and the carrier are stirred and dispersed uniformly in a first solvent, and filtered to obtain a carrier modified by the modifier.

[0033] Preferably, in step (2), the second solvent is selected from one or a combination of at least two of water, ethanol, methanol or isopropanol.

[0034] In the present invention, the metal salt and the choline substance are stirred and mixed in the second solvent to obtain a mixed solution.

[0035] Preferably, the mixing in step (2) is carried out at a temperature of 60°C to 120°C (e.g., 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C or 120°C), preferably 80°C to 120°C; and the mixing time is 2 to 5 hours (e.g., 2 hours, 3 hours, 4 hours or 5 hours), preferably 2 to 4 hours.

[0036] Preferably, the stirring in step (3) is carried out at a temperature of 30-60°C (e.g., 30°C, 35°C, 40°C, 45°C, 50°C, 55°C or 60°C), preferably 30-50°C; the stirring time is 2-6 hours (e.g., 2 hours, 3 hours, 4 hours, 5 hours or 6 hours), preferably 4-6 hours.

[0037] On the other hand, the present invention provides a method for preparing a p-methoxycinnamate compound, comprising the following steps: catalyzing a Claison-Schmidt condensation reaction of an aromatic aldehyde compound and an ester compound in the presence of a catalyst to obtain p-methoxycinnamate, wherein the catalyst is the composite catalyst described above.

[0038] The present invention uses a composite catalyst to prepare p-methoxycinnamate compounds, so that the reaction is carried out under relatively mild conditions, the product can be produced in high yield, and there is no corrosion to equipment, no wastewater or waste salt is generated, and it is environmentally friendly. The general reaction formula of the present invention is as follows:

[0039]

[0040] wherein R1 is selected from hydrogen or methoxy, and R2 is selected from hydrogen, C1-C10 (e.g., C1, C2, C3, C4, C5, C6, C7, C8, C9 or C10) linear or branched alkyl.

[0041] Preferably, the aromatic aldehyde compound is benzaldehyde and / or p-anisaldehyde.

[0042] Preferably, the ester compound is one or a combination of at least two of methyl acetate, ethyl acetate, butyl acetate, isooctyl acetate, isopentyl acetate or diethyl malonate.

[0043] Preferably, the mass ratio of the composite catalyst to the aromatic aldehyde compound is 0.03-0.09:1, for example, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1 or 0.09:1, preferably 0.05-0.09:1.

[0044] Preferably, the molar ratio of the aromatic aldehyde compound to the ester compound is 1:1-3, for example, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, preferably 1:1-2, more preferably 1:1.2-1.6.

[0045] Preferably, the temperature of the condensation reaction is 40°C to 80°C, such as 40°C, 45°C, 48°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C, preferably 40°C to 60°C.

[0046] Preferably, the condensation reaction time is 1 to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours or 5 hours, preferably 2 to 4 hours.

[0047] In the present invention, the Clauson-Schmidt condensation reaction is carried out with or without a solvent. If a solvent is used, water, ethanol, isopropanol, methanol and other low-toxic or non-toxic solvents can be selected, preferably water.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] (1) The composite catalyst provided by the present invention has high reaction activity and selectivity, a stable catalyst structure, and the active components are not easily lost. The catalyst can be recycled without frequent catalyst replacement. The operation is simple, which is conducive to continuous industrial production and significantly improves equipment utilization.

[0050] (2) The composite catalyst provided by the present invention can be used to prepare methoxycinnamate compounds under relatively mild reaction conditions, without causing corrosion to the equipment, and without generating wastewater or waste salt, thereby being environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 is an electron microscope photograph of catalyst 1;

[0052] Figure 2 The mass spectrum of the product obtained in Application Example 1 (Figure A) is compared with the standard spectrum of the substance in the mass spectrum library (Figure B);

[0053] Figure 3 This is the gas phase spectrum of the product obtained in Application Example 1. DETAILED DESCRIPTION

[0054] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0055] Catalyst Preparation Example 1

[0056] (1) Add polydimethylsiloxane (30 g) and carrier HPD300 (10 g) to 30 mL of purified water in a mass ratio of 3:1. Start stirring and heat to 100 °C. Keep stirring for 3 hours, then cool to room temperature and filter to obtain the modified carrier.

[0057] (2) At room temperature, add ZnCl₂ (1.042 g, 7.64 mmol) and choline chloride (3.202 g) to 40 mL of purified water in a mass ratio of 1:3. Stir the mixture and raise the temperature to 100°C. Stir and maintain the mixture for 3 hours to obtain a mixed solution.

[0058] (3) Add the modified carrier in (1) to the mixed solution in (2), cool to 40°C, and stir for 5 hours. Filter while hot, and dry the filter cake to constant weight to obtain catalyst 1.

[0059] The catalyst 1 was characterized by scanning electron microscopy (instrument model: JEOL JSM-6701F). Figure 1 As shown in the electron microscope photograph magnified 10,000 times, it can be seen that the active components are distributed on the surface and in the pores of the carrier, and the dispersion is almost uniform, exposing more active sites. The catalyst shows high activity and selectivity.

[0060] Catalyst Preparation Examples 2-11

[0061] Examples 2 to 11 provide a method for preparing a composite catalyst, respectively. The only difference compared to Example 1 is that the ZnCl2 metal salt in Example 1 is replaced by FeCl3 (1.452 g, 8.95 mmol), FeCl3·6H2O (2.420 g, 8.95 mmol), FeCl2 (1.135 g, 8.95 mmol), CuCl2 (1.058 g, 7.87 mmol), CuCl2·2H2O (1.341 g, 7.87 mmol), CuCl (0.779 g, 7.87 mmol), CoCl2·6H2O (2.019 g, 8.48 mmol), CoCl2 (1.102 g, 8.48 mmol), NiCl2 (1.104 g, 8.52 mmol), and NiCl2·6H2O (2.025 g, 8.52 mmol), respectively, and the types and amounts of choline chloride, carrier, and modifier are kept unchanged.

[0062] Examples 12 to 15

[0063] Examples 12 to 15 provide a method for preparing a composite catalyst, respectively. The only difference from Example 1 is that the mass ratios of the active metal element to the carrier are 0.01:1, 0.03:1, 0.07:1, and 0.09:1, respectively, and the amounts of metal salt and choline chloride added are adjusted as shown in Table 1.

[0064] Table 1

[0065]

[0066] Examples 16 to 21

[0067] Examples 16 to 21 provide a method for preparing a composite catalyst, respectively. The only difference compared to Example 1 is that the choline chloride in Example 1 is replaced with β-methylcholine chloride (3.524 g), benzoylcholine chloride (5.589 g), butyrylcholine chloride (4.809 g), choline chloride (3.625 g), phosphorylcholine (5.036 g), and acetylcholine chloride (4.166 g), respectively, and the types and amounts of metal salts, carriers, and modifiers are kept unchanged.

[0068] Examples 22 to 25

[0069] Examples 22 to 25 provide a composite catalyst, respectively. The only difference from Example 1 is that the amount of choline chloride added is adjusted, as shown in Table 2, so that the mass ratios of choline chloride to metal salt are 1:1, 2:1, 4:1, and 5:1, respectively.

[0070] Table 2

[0071]

[0072] Examples 26-29

[0073] Examples 26 to 29 provide a composite catalyst, respectively. The only difference compared with Example 1 is that the amount of the modifier added is adjusted, as shown in Table 3, so that the mass ratios of the modifier and the carrier are 1:1, 2:1, 4:1, and 5:1, respectively.

[0074] Table 3

[0075]

[0076] Examples 30-41

[0077] The present embodiments 30 to 41 provide a composite catalyst, which differs from embodiment 1 only in that the modifiers in embodiment 1 are replaced by vinyl pentamethyl disiloxane, hexaethyl disiloxane, 1,1,1,3,5,5,5-heptamethyl trisiloxane, polyphenylmethylsiloxane (CAS No. 9005-12-3 ; Aladdin), polymethylhydrogensiloxane (CAS No.: 63148-57-2 ; Aladdin), hexamethyldisiloxane, pentamethyldisiloxane, hexamethoxydisiloxane, dodecamethylpentasiloxane, decamethyltetrasiloxane, hexamethylcyclotrisiloxane, octamethyltrisiloxane, and keep the quality of the modifier unchanged.

[0078] Examples 42 to 57

[0079] Examples 42 to 57 provide a method for preparing a composite catalyst, respectively. The only difference from Example 1 is adjusting the temperature and time of the reaction between the metal salt and choline chloride, the temperature and time of the reaction between the support and the modifier, and the temperature and time of the adsorption and stirring of the support, as shown in Table 4.

[0080] Table 4

[0081]

[0082] Examples 58-63

[0083] Examples 58 to 63 provide a composite catalyst, respectively. The only difference compared with Example 1 is that the carrier in Example 1 is replaced with D3520, D141, S-8, HZ801, XAD16N, and DM11, respectively, while keeping the quality of the carrier unchanged.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing a composite catalyst. The difference between the preparation method and Example 1 is that choline chloride is not added. The preparation method comprises the following steps:

[0086] Polydimethylsiloxane (30 g) and the carrier HPD300 (10 g) were added to 30 mL of purified water in a 3:1 mass ratio. Stirring was initiated, the mixture was heated to 100°C, stirred for 3 hours, cooled to room temperature, and filtered to obtain the modified carrier. ZnCl2 (1.042 g, 7.64 mmol) was then added, the temperature was lowered to 40°C, and stirred for 5 hours. The mixture was filtered while hot, and the filter cake was dried to constant weight to obtain the catalyst of Comparative Example 1.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing a composite catalyst. The difference between the preparation method and Example 1 is that no modifier is added. The preparation method comprises the following steps:

[0089] At room temperature, add ZnCl2 (1.042 g, 7.64 mmol) and choline chloride (3.202 g) to 40 mL of purified water in a 1:3 mass ratio. Stirring was initiated and the temperature was raised to 100°C. After stirring for 3 hours, the carrier HPD300 (10 g) was added. The temperature was lowered to 40°C and stirred for 5 hours. The mixture was filtered while hot and the filter cake was dried to constant weight to obtain the catalyst for Comparative Example 2.

[0090] Comparative Example 3

[0091] At room temperature, add ZnCl2 (1.042 g, 7.64 mmol) and choline chloride (3.202 g) to 40 mL of purified water in a 1:3 mass ratio. Stirring was initiated and the mixture was heated to 100°C. After stirring for 3 hours, polydimethylsiloxane (30 g) was added and stirred at 100°C for 3 hours to obtain a mixed solution. Excess water was removed to obtain a viscous liquid, thus obtaining the catalyst for Comparative Example 3.

[0092] Comparative Example 4

[0093] Polydimethylsiloxane (30 g) and carrier HPD300 (10 g) were added to 30 mL of purified water in a mass ratio of 3:1. Stirring was started, the temperature was raised to 100° C., and the mixture was kept warm and stirred for 3 hours, then cooled to room temperature. Choline chloride (3.202 g) was added, and the mixture was kept warm and stirred at 100° C. for 3 hours. The mixture was cooled to 40° C. and kept warm and stirred for 5 hours. The mixture was filtered while hot, and the filter cake was dried to constant weight to obtain the catalyst of Comparative Example 4.

[0094] Comparative Example 5

[0095] (1) Add polydimethylsiloxane (30 g) and silicon dioxide (10 g) to 30 mL of purified water in a mass ratio of 3:1. Start stirring and heat to 100 °C. Keep stirring for 3 hours, then cool to room temperature and filter to obtain the modified carrier.

[0096] (2) At room temperature, add ZnCl₂ (1.042 g, 7.64 mmol) and choline chloride (3.202 g) to 40 mL of purified water in a mass ratio of 1:3. Stir the mixture and raise the temperature to 100°C. Stir and maintain the mixture for 3 hours to obtain a mixed solution.

[0097] The modified carrier in (1) was added to the mixed solution in (2), cooled to 40°C, and stirred for 5 hours. The mixture was filtered while hot, and the filter cake was dried to constant weight to obtain the catalyst of Comparative Example 5.

[0098] Application Example 1

[0099] Catalyst 1 (1.0 g, 1.0% catalyst concentration) and octyl acetate (151.84 g, 0.8814 mol) were added sequentially to a 500 mL four-necked flask. After heating to 60°C, p-anisaldehyde (100 g, 0.7345 mol) was added dropwise over 1 hour. After complete addition of p-anisaldehyde, the reaction was incubated for 3 hours. The reaction solution was sampled via a bottom-dip tube in the reactor and analyzed by GC. The conversion of the raw p-anisaldehyde was 97.10%, yielding the product, isooctyl p-methoxycinnamate (OMC), with a selectivity of 98.30%.

[0100] Then, 203.08 g of pure isooctyl p-methoxycinnamate OMC was obtained by distillation with a purity of >99.5% and a yield of 95.21%.

[0101] Mass spectrum:

[0102] Mass spectrometer: Agilent 5977C;

[0103] Detection conditions: column type DB~17 (30m×0.32mm×0.25μm); injector: 250℃; detector: 300℃; column temperature: 70℃ for 2 min, then increase to 250℃ at 40℃ / min and hold for 20 min, total run time 26.5 min.

[0104] Figure 2 The mass spectrum of 2-ethylhexyl 4-methoxycinnamate obtained in Application Example 1 (Figure A) is compared with the standard spectrum (Figure B) No. 150019. It can be seen that they are completely consistent with the standard spectrum, proving that the target product 2-ethylhexyl 4-methoxycinnamate is produced in the reaction product, with a corresponding molecular weight of 290.1.

[0105] Figure 3 This is the gas phase spectrum of isooctyl p-methoxycinnamate obtained in Application Example 1. The content is 99.51%, which meets the standard. The gas phase detection conditions are:

[0106] Gas chromatograph: Fuli 9790;

[0107] Detection conditions: column type DB~17 (30m×0.32mm×0.25μm); injector: 250℃; detector: 300℃; column temperature: 70℃ for 2 min, then increase to 250℃ at 40℃ / min and hold for 20 min, total run time 26.5 min.

[0108] Application Examples 2~5

[0109] The only difference between Application Examples 2 to 5 and Application Example 1 is that the amount of catalyst 1 is changed to 3.0%, 5.0%, 7.0%, and 9.0%, respectively. The corresponding catalyst amounts are 3.0g, 5.0g, 7.0g, and 9.0g, respectively. The rest are the same as Application Example 1. The results are shown in Table 5.

[0110] Among them, taking the process of preparing isooctyl p-methoxycinnamate provided in Application Example 4 as an example, the reaction liquid after the reaction is filtered and separated, and the filtered catalyst is washed with deionized water 2 to 3 times to obtain a recovered catalyst. The recovered catalyst is again used to perform the method for preparing pseudo isooctyl p-methoxycinnamate provided in Application Example 4, and the catalyst is applied. The first use of the catalyst is applied once, the second use of the catalyst is applied twice, and so on. The conversion rate of p-methoxybenzaldehyde and the selectivity of p-methoxycinnamate are calculated, and the results are shown in Table 6.

[0111] Application Examples 6-12

[0112] The only difference between Application Examples 6 to 12 and Application Example 4 is the molar ratio of isooctyl acetate to p-anisaldehyde, which are 1.0:1, 1.4:1, 1.6:1, 1.8:1, 2.0:1, 2.5:1, and 3.0:1, respectively. The corresponding molar amounts of isooctyl acetate are 0.7345 mol, 1.0283 mol, 1.1752 mol, 1.3221 mol, 1.4690 mol, 1.8362 mol, and 2.2035 mol, respectively. The other conditions are the same as those in Application Example 4. The results are shown in Table 5.

[0113] Application Examples 13-16

[0114] Application Examples 13-16 differ from Application Example 4 only in the type of acetate used: methyl acetate (65.29 g, 0.8814 mol), ethyl acetate (77.66 g, 0.8814 mol), butyl acetate (102.38 g, 0.8814 mol), and isoamyl acetate (114.74 g, 0.8814 mol). The remaining reactions were the same as in Application Example 4. The results are shown in Table 5.

[0115] Application Examples 17-21

[0116] Application Examples 17-21 differed from Application Example 4 only in the reaction temperature and reaction time; otherwise, they were the same as in Application Example 4. The reaction temperatures for Application Examples 17 and 18 were 40°C and 80°C, respectively, with the other conditions being the same as in Application Example 4. The reaction times for Application Examples 19, 20, and 21 were 2 hours, 4 hours, and 5 hours, respectively, with the other conditions being the same as in Application Example 4. The results are shown in Table 5.

[0117] Application Examples 22~83

[0118] Application Examples 22 to 83 provide an application of a composite catalyst, respectively. The composite catalysts are sequentially prepared using the composite catalysts provided in Examples 2 to 63 above, and are used to prepare isooctyl p-methoxycinnamate. The preparation method includes:

[0119] After heating the catalyst (7.0 g, catalyst concentration 7.0%) and octyl acetate (151.84 g, 0.8814 mol) to 60°C, p-anisaldehyde (100 g, 0.7345 mol) was added dropwise over 1 hour. After the addition of p-anisaldehyde was complete, the reaction was incubated for 3 hours. After the reaction, the reaction solution was analyzed by GC, and the p-anisaldehyde conversion and selectivity for isooctyl p-methoxycinnamate were calculated. The results are shown in Table 5.

[0120] Application Comparative Examples 1 to 5

[0121] Comparative Examples 1 to 5 of this application each provide an application of a composite catalyst, differing from Application Example 4 only in that the composite catalysts provided in Comparative Examples 1 to 5 are used, respectively. After the reaction, the reaction solution was analyzed using a gas chromatograph to calculate the conversion of p-anisaldehyde and the selectivity for isooctyl p-methoxycinnamate. The results are shown in Table 5.

[0122] Table 5

[0123]

[0124]

[0125]

[0126]

[0127]

[0128] Table 6

[0129]

[0130] Application Example 84

[0131] Application Example 84 differed from Application Example 4 only in the use of 100 g of water as the solvent in a 1:1 ratio with p-anisaldehyde. All other conditions were the same as in Application Example 4. GC analysis of the reaction solution revealed a 97.30% conversion of the p-anisaldehyde starting material, yielding the product, isooctyl p-methoxycinnamate (OMC), with a selectivity of 98.80%. Rectification and purification were then performed to obtain 204.53 g of pure isooctyl p-methoxycinnamate (OMC) with a purity of >99.5% and a yield of 95.89%.

[0132] The applicant states that while the above-described embodiments illustrate the composite catalyst and the method for synthesizing p-methoxycinnamate compounds, the present invention is not limited to these embodiments. This does not necessarily mean that the present invention must rely on these embodiments in order to be implemented. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a p-methoxycinnamate compound, characterized in that: The preparation method comprises the following steps: catalyzing a Claison-Schmidt condensation reaction of an aromatic aldehyde compound and an ester compound in the presence of a catalyst to obtain p-methoxycinnamate; The general reaction formula is as follows: ； wherein R1 is selected from hydrogen or methoxy, and R2 is selected from hydrogen, C1-C10 straight or branched chain alkyl; The catalyst is a composite catalyst, which includes a carrier modified by a modifier and a metal salt and a choline substance supported by the carrier; The modifier is organic siloxane; the carrier is macroporous adsorption resin.

2. The preparation method according to claim 1, characterized in that The modifier is selected from one or a combination of at least two of vinyl pentamethyl disiloxane, hexaethyl disiloxane, 1,1,1,3,5,5,5-heptamethyl trisiloxane, polyphenylmethylsiloxane, polymethyl hydrogen siloxane, hexamethyl disiloxane, hexamethoxy disiloxane, pentamethyl disiloxane, dodecamethyl pentasiloxane, decamethyl tetrasiloxane, hexamethyl cyclotrisiloxane, octamethyl trisiloxane, and polydimethylsiloxane; The vector is one or a combination of at least two of D3520, D141, S-8, HPD300, HZ801, XAD16N or DM11; The mass ratio of the modifier to the carrier is 1-5:1; The mass ratio of the metal salt to the carrier is 0.01-0.09:1; The metal salt is any one or a combination of at least two of zinc, iron, copper, cobalt, nickel hydrochloride or hydrates of the hydrochloride; The choline substance is one or a combination of at least two of choline chloride, β-methylcholine chloride, benzoylcholine chloride, butyrylcholine chloride, choline chloride, phosphorylcholine or acetylcholine chloride; The molar ratio of the metal salt to the choline substance is 1:1-5.

3. The preparation method according to claim 2, characterized in that The mass ratio of the modifier to the carrier is 2-4:1; the mass ratio of the metal salt to the carrier is 0.03-0.07:1; and the molar ratio of the metal salt to the choline substance is 1:1-4.

4. The preparation method according to claim 2 or 3, characterized in that The mass ratio of the metal salt to the carrier is 0.03-0.05:1; the molar ratio of the metal salt to the choline substance is 1:2-3.

5. The preparation method according to claim 1, characterized in that The preparation method of the composite catalyst comprises the following steps: (1) The modifier and the carrier are mixed in a first solvent and reacted to obtain a carrier modified by the modifier; (2) mixing the metal salt and the choline substance in a second solvent to obtain a mixed solution; (3) Adding the carrier modified by the modifying agent obtained in step (1) to the mixed solution obtained in step (2), stirring, adsorbing, filtering, removing the solvent, and drying to obtain the composite catalyst.

6. The preparation method according to claim 5, characterized in that The reaction temperature in step (1) is 60°C to 120°C; The reaction time of step (1) is 1 to 5 hours; Step (1) the first solvent is selected from one or a combination of at least two of water, ethanol, methanol or isopropanol; Step (2) the second solvent is selected from one or a combination of at least two of water, ethanol, methanol or isopropanol; The mixing in step (2) is carried out at a temperature of 60°C to 120°C and for a time of 2 to 5 hours; The stirring in step (3) is carried out at a temperature of 30 to 60° C.; the stirring time is 2 to 6 hours.

7. The preparation method according to claim 5, characterized in that The reaction temperature of step (1) is 80°C to 100°C, and the reaction time of step (1) is 2 to 3 hours; The mixing in step (2) is carried out at a temperature of 80°C to 120°C and for a time of 2 to 4 hours; The stirring in step (3) is carried out at a temperature of 30-50° C., and the stirring time is 4-6 hours.

8. The preparation method according to claim 1, characterized in that The ester compound is one or a combination of at least two of methyl acetate, ethyl acetate, butyl acetate, isooctyl acetate, isopentyl acetate or diethyl malonate; The mass ratio of the composite catalyst to the aromatic aldehyde compound is 0.03-0.09:1; The molar ratio of the aromatic aldehyde compound to the ester compound is 1:1-3; The temperature of the condensation reaction is 40°C to 80°C; The condensation reaction time is 1 to 5 hours; The Claison-Schmidt condensation reaction is carried out with or without a solvent; The solvent is selected from any one of water, ethanol, isopropanol or methanol, or a combination of at least two thereof.

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