CN110143878B - Preparation method of methyl p-methoxycinnamate - Google Patents
Preparation method of methyl p-methoxycinnamate Download PDFInfo
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Abstract
The invention discloses a preparation method of methyl p-methoxycinnamate. Adding methyl acetate, methanol, sodium methoxide and cyclic ether into a condensation reaction kettle, and reacting at reflux temperature; then adding p-methoxybenzaldehyde, simultaneously circulating the reaction liquid through a reaction bed filled with a catalyst, after the p-methoxybenzaldehyde is added, carrying out reflux and heat preservation to continue the reaction, and separating and removing water generated in the reaction. The method has the advantages that the use amount of the catalyst can be reduced to a very low level by adding and removing the generated water through methanol and cyclic ether, the 3-methoxy-3-p-methoxyphenyl methyl propionate generated in the reaction process is timely converted into p-methoxy methyl cinnamate by circulating the reaction liquid through a reaction bed filled with a metal oxide catalyst, the purity and the yield of the product are improved, meanwhile, an acid-base neutralization process is not needed, redundant wastewater and other solid wastes are not generated, and compared with the traditional process, the method has equivalent or higher conversion rate and selectivity, lower production cost and more environmental protection.
Description
Technical Field
The invention belongs to the field of chemical industry, relates to a preparation method of p-methoxy cinnamate, and particularly relates to a preparation method of methyl p-methoxy cinnamate.
Background
P-methoxycinnamate, especially the higher esters of p-methoxycinnamate, are excellent UV absorbers and are useful as chemical sunscreens. Methyl p-methoxycinnamate is a raw material for synthesizing higher p-methoxycinnamate, and has important application in the pharmaceutical field.
At present, the mainstream preparation method of p-methoxy cinnamate in industry is that p-methoxy benzaldehyde is used as a raw material and is prepared through a Claisen-Schmidt reaction route:
the p-methoxybenzaldehyde and methyl acetate are subjected to catalytic reaction in a conventional hydrocarbon solvent by using strong bases such as sodium methoxide and the like as catalysts, the reaction is carried out for 2-6 hours at the temperature of 40-65 ℃, and then a corresponding product is obtained after post-treatment.
Chinese patent CN105503596 discloses a preparation method of sunscreen isooctyl p-methoxycinnamate, which adopts the Claisen-Schmidt route to uniformly mix and stir p-methoxybenzaldehyde, methyl acetate, sodium alkoxide solution and isooctyl alcohol, and react for 3-8 hours at 55-75 ℃. And then adjusting the pH value to 12-14 by using a non-oxidizing acid, reducing the pressure, heating to 70-110 ℃, reacting for 2-8, recovering the low-boiling-point solvent, washing the reaction solution to be neutral by using an acid, removing the solvent, rectifying to obtain isooctyl p-methoxycinnamate, and recovering isooctyl alcohol. The patent reports that the total yield is 87-90%, which reaches a relatively ideal level, but the molar ratio of sodium methoxide to isooctyl p-methoxycinnamate as a catalyst is (1-1.2): 1, the catalyst has large dosage and high cost, and simultaneously, a large amount of acid is needed to neutralize the alkalinity of a system after the reaction is finished, so that a large amount of waste water is generated, and the environmental protection cost is increased.
US patent No. 5527947 discloses an improved process for the preparation of cinnamate compounds which comprises: (a) dissolving C1-C4 alkoxybenzaldehyde and C1-C4 alkyl acetate in a conventional hydrocarbon solvent; (b) reacting the resulting solution under mild conditions and in the presence of a strong alkali metal base; (c) acidifying the resulting mixture; (d) esterifying said acetic acid and stripping the esterified acetic acid from the mixture; (e) reacting the remaining C1-C4 alkoxycinnamic acid C1-C4 alkyl esters and C1-C4 alkoxycinnamic acids with C5-C14 alkanols in the presence of said strong alkali metal salt of polybasic acid suspension; (f) recovering the product. The total yield reported by the patent is 83-87%, the generation amount of waste liquid is greatly reduced by ingenious solvent circulation, but the molar ratio of sodium methoxide serving as a catalyst to isooctyl p-methoxycinnamate is 1.06: 1, the problems of large catalyst dosage and high catalyst cost still exist, and the patent does not mention the specific content of 3-alkoxy-3-p-methoxyphenyl propionate.
Japanese patent JPS617236A describes a process for the preparation of cinnamate esters by a condensation reaction between benzaldehyde and an acetate ester using a metal alkoxide as a base. However, since 4.7 to 12.5% of 3-methoxy-3-phenylpropionate is produced as a by-product, the method requires a purification step such as distillation in order to separate cinnamate from the reaction mixture. Therefore, this method has problems such as low yield, difficult purification and disposal of by-products.
Japanese patent JP3786528B2 discloses a process for preparing cinnamate esters which comprises condensing benzaldehyde with methyl acetate in the presence of a base. And then treating the reaction mixture with liquid acid after adding no additional solvent or adding additional solvent so as to convert the 3-alkoxy-3-phenyl propionate in the mixture into corresponding cinnamate, wherein the reaction liquid before treatment contains 7-16% of 3-alkoxy-3-phenyl propionate in a molar ratio. The total yield is 82-97.5%, but the dosage of the metal alkoxide of the catalyst is preferably 1-2 equivalents of benzaldehyde, the dosage of the catalyst is large, the cost of the catalyst is high, and a large amount of acid is needed to neutralize the alkalinity of a system after the reaction is finished, so that a large amount of waste water is generated, and the environmental protection cost is increased.
German patent EP0165521 discloses a method for preparing an optionally substituted cinnamate and an optionally substituted β -alkoxy- β -phenylpropionate, the molar ratio of the amount of the added catalyst to benzaldehyde is 1.1:1, the amount of the added catalyst is large, the cost of the catalyst is high, a large amount of waste water is generated in the acid-base neutralization process, the environmental protection cost is increased, and an alkali metal hydroxide is required to be added to treat a reaction solution in order to prepare the optionally substituted β -alkoxy- β -phenylpropionate into the optionally substituted cinnamate.
German patent DE3028417 discloses a process for the preparation of p-methoxycinnamate in a molar ratio of catalyst addition to p-methoxybenzaldehyde of 0.67:1, which, although reduced compared to other patent disclosures, still results in higher catalyst addition and higher costs, and also results in large amounts of waste water during neutralization, which increases environmental costs.
In order to improve the yield and purity of methyl p-methoxycinnamate, JP617236 discloses a method of separating methyl 3-methoxy-3-p-methoxyphenylpropionate, which reduces the reaction yield, JP283462 discloses a method of converting methyl 3-methoxy-3-p-methoxyphenylpropionate into methyl p-methoxycinnamate by treating a reaction solution containing methyl 3-methoxy-3-p-methoxyphenylpropionate after the reaction with a liquid acid, which improves the reaction yield but involves a multiple acid-base neutralization process and increases the amount of salt-containing wastewater, and EP0165521 discloses a method of converting methyl 3-methoxy-3-p-methoxyphenylpropionate into methyl p-methoxycinnamate by treating a reaction solution containing methyl 3-methoxy-3-p-methoxyphenylpropionate after the reaction with a basic hydroxide, the same problem is found in patent JP 283462.
In view of the shortcomings of this route, it is very necessary to develop a process that is low in catalyst cost and safe and environmentally friendly. The process has the advantages of equivalent or higher conversion rate and selectivity, lower production cost and more environmental protection, so as to overcome the technical defects of the process.
Disclosure of Invention
The invention aims to provide a preparation method of methyl p-methoxycinnamate, which has equivalent or higher conversion rate and selectivity, lower production cost and more environmental protection compared with the traditional process.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
a process for the preparation of methyl p-methoxycinnamate comprising the steps of:
a) adding methyl acetate, methanol, sodium methoxide and cyclic ether into a condensation reaction kettle, stirring at a reflux temperature, and keeping the temperature for 0.2-1 h;
b) adding p-methoxybenzaldehyde into a condensation reaction kettle, simultaneously circulating a reaction solution through a reaction bed filled with a catalyst, carrying out reflux heat preservation after the p-methoxybenzaldehyde is added, continuing to react for 0.5-5 h, and separating and removing water generated in the reaction process through a rectifying tower, a condensation heat exchanger and an inorganic pervaporation membrane device.
The reaction route of the invention is shown as the following formula:
in the process of preparing the methyl p-methoxycinnamate, water is generated, and the sodium methoxide is very easy to generate methanol and sodium hydroxide when contacting with the water, so the following reactions are inevitable:
CH3ONa+H2O→CH3OH+NaOH
in order to achieve the purpose of the invention, the inventor skillfully adds a certain amount of methanol to ensure that the addition amount of sodium methoxide in the reaction process is in a very low level, so the following reaction is crucial to the invention:
CH3OH+NaOH→CH3ONa+H2O
the addition of methanol resulted in a significant decrease in the main reaction rate of p-methoxybenzaldehyde and methyl acetate, and a decrease in the product selectivity, which was not thought by the inventors. After many experimental investigations, the inventors have surprisingly found that the problem of the reduced reaction rate due to the addition of methanol can be solved by adding a specific cyclic ether in a suitable amount to the system.
It is also essential to the present invention that the water produced by the reaction of p-methoxybenzaldehyde and methyl acetate and/or the water produced by the reaction of methanol and sodium hydroxide be removed efficiently and in a timely manner.
In the process of preparing the methyl p-methoxycinnamate, a byproduct, namely 3-methoxy-3-p-methoxyphenyl methyl propionate is also generated:
in order to obtain the methyl p-methoxycinnamate with high yield and high purity and simultaneously not increase the quantity of three wastes, the method adopted by the invention is to circulate reaction liquid through a reaction bed filled with a specific metal oxide catalyst in the reaction process and convert the methyl 3-methoxy-3-p-methoxyphenylpropionate generated in the reaction process into the methyl p-methoxycinnamate in time.
The traditional process route has the advantages that the addition amount of sodium alkoxide serving as a catalyst is very large, the molar ratio of the sodium alkoxide to a substrate p-methoxybenzaldehyde is generally more than 1:1, most of the sodium alkoxide can react with water generated in the reaction and cannot play a role in catalysis, and meanwhile, in order to obtain p-methoxycinnamate with high yield and high purity, liquid acid and/or alkaline hydroxide are/is required to be used for treating a reaction mixture, so that the waste liquid amount is huge.
The method can skillfully solve the problem of failure caused by the reaction of the sodium alkoxide and the water, further greatly reduce the using amount of the catalyst and reduce the cost of the catalyst, and can obtain the methyl p-methoxycinnamate with high yield and high purity under the condition of not using liquid acid and/or alkaline hydroxide to treat the reaction mixture, thereby greatly reducing the treatment cost of three wastes.
According to the method, the methanol and the specific cyclic ether are added, water generated in the reaction process is removed in time, the use amount of a catalyst sodium methoxide is reduced, the reaction liquid is circulated through a reaction bed filled with a specific metal oxide catalyst, the 3-methoxy-3-p-methoxyphenyl methyl propionate generated in the reaction process is converted into the p-methoxy methyl cinnamate in time, the purity and the yield of the product p-methoxy methyl cinnamate are improved, an acid-base neutralization process is not needed, the use amount of the catalyst can be greatly reduced through the route, the acid-base neutralization is not needed, no extra waste water or other solid wastes are generated, and the production cost is saved, so that the purpose of the invention is achieved.
The molar ratio of methyl acetate to p-methoxybenzaldehyde in the step a) is 1.1-10: 1, preferably 2-8: 1.
The molar ratio of the methanol to the p-methoxybenzaldehyde in the step a) is 2-100: 1, preferably 5-15: 1.
The cyclic ether in step a) is preferably dioxane, trioxane, 1, 3-dioxane, 1, 3-dioxolane, more preferably 1, 3-dioxolane.
The molar ratio of the cyclic ether to the methanol in the step a) is 0.2-1: 1, preferably 0.4-0.6: 1.
The molar ratio of the sodium methoxide to the p-methoxybenzaldehyde in the step a) is 0.05-0.5: 1, preferably 0.15-0.3: 1.
The charging time of the p-methoxybenzaldehyde in the step b) is 0.5-2 hours, and preferably 1-1.5 hours.
Preferably, the feeding temperature of the p-methoxybenzaldehyde in the step b) and the holding temperature after the feeding are both reflux temperatures.
Preferably, the reflux heat preservation time after the p-methoxybenzaldehyde is added in the step b) is preferably 1-3 h.
The temperature and pressure of the reaction bed in step b) preferably correspond to the condensation reactor temperature and pressure.
The filling volume of the catalyst in the reaction bed in the step b) is preferably 1/10-1/3, more preferably 1/6-1/4 of the total volume of the materials added into the condensation reaction kettle.
The circulation flow of the reaction liquid in the step b) is preferably selected to ensure that the reaction liquid is circulated once every 5-10 minutes.
The composition of the catalyst filled in the reaction bed in the step b) is as follows: 53.1-81.6% of gamma-alumina, 3.2-6.4% of calcium oxide, 3-6.5% of magnesium oxide, 0.5-2.2% of cerium oxide, 50-500 ppm of manganese oxide, preferably 105-315 ppm, 30-400 ppm of rhenium oxide, preferably 50-215 ppm, and 10.2-32.3% of alumina sol.
Preferably, the mass ratio of manganese oxide to rhenium oxide in the catalyst filled in the reaction bed in the step b) is 0.3-10, preferably 0.5-6.
A process for preparing the catalyst of step b) of the present invention, comprising the steps of:
1) uniformly mixing gamma-alumina and polyethylene glycol; then adding calcium oxide, magnesium oxide, cerium oxide, manganese oxide and rhenium oxide into the mixture, and uniformly mixing;
2) adding alumina sol into the mixture obtained in the step 1), forming, drying and roasting to obtain the catalyst.
In the preparation method of the catalyst, the dosage of each substance is as follows: calculated by the total weight of each substance,
50-80% of gamma-alumina, 2-7% of polyethylene glycol, 3-6% of calcium oxide, 3-6% of magnesium oxide, 0.5-2% of cerium oxide, 50-500 ppm of manganese oxide, preferably 100-300 ppm, 30-400 ppm of rhenium oxide, preferably 50-200 ppm, and 10-30% of aluminum sol (based on the mass of solids in the aluminum sol).
Preferably, in the preparation method of the catalyst, the mass ratio of the manganese oxide to the rhenium oxide is 0.3-10, and preferably 0.5-6.
The manganese oxide and the rhenium oxide with a certain proportion are added, so that a synergistic catalytic effect can be achieved with the main active component in the catalyst, and the activity of the catalyst for removing the 3-methoxyl group in the 3-methoxyl-3-p-methoxyl phenyl methyl propionate is obviously improved.
The polyethylene glycol in the step 1) is used for pore forming, the number average molecular weight is preferably 1000-6000, and other organic pore forming agents can be used for substitution.
The aluminum sol has the function of a binder, has the solid content of 20-25 wt%, and can be replaced by other binders.
The forming mode of the catalyst in the step 2) can be rolling balls or extrusion strips, and the extrusion strips are preferred.
The drying temperature in the step 2) is 95-110 ℃, preferably 98-102 ℃, and the drying time is 12-24 hours, preferably 15 hours.
The roasting temperature in the step 2) is 450-650 ℃, the roasting time is 10-15 hours, and preferably the roasting time is 10-12 hours at 580-620 ℃.
The present invention can be carried out under a pressurized, normal pressure or reduced pressure condition, and is preferably carried out under a nitrogen atmosphere.
Drawings
FIG. 1 is a schematic flow diagram of one embodiment of the process of the present invention.
Wherein, 1: p-methoxybenzaldehyde; 2: a condensation reaction kettle; 3: a rectifying tower; 4: a condensing heat exchanger; 5: inorganic pervaporation membrane devices; 6: water; 7: a reflux pump; 8: a circulation pump; 9: a reaction bed; 10: and (6) discharging.
Detailed Description
The present invention is further illustrated by the following examples, but is not limited thereto.
The quantitative analysis of each organic matter involved in the invention is carried out on an Agilent 7890B type gas chromatography, and the analysis conditions of the gas chromatography are as follows:
a chromatographic column: agilent HP-5 capillary chromatographic column (specification of 30m × 0.32mm × 0.25 μm)
Sample inlet temperature: 280 deg.C
The split ratio is as follows: 30: 1
Column flow rate: 1.5ml/min
Column temperature: 0.5min at 100 DEG C
Increasing the temperature to 260 ℃ at 15 ℃/min and keeping the temperature for 8min
Detector temperature: 280 ℃, hydrogen flow rate: 35ml/min
Air flow rate: 350ml/min
The invention is further illustrated by the following specific examples.
Preparing a catalyst:
example 1:
529.7 g of gamma-alumina powder and 70 g of polyethylene glycol (molecular weight 1000) powder are uniformly mixed, then 30 g of calcium oxide powder, 60 g of magnesium oxide powder, 10 g of cerium oxide, 100 mg of manganese oxide and 200 mg of rhenium oxide powder are sequentially added into the mixture of the gamma-alumina powder and the polyethylene glycol, the mixture is uniformly stirred, then a solution containing 300 g of aluminum sol is added, the catalyst is formed by an extrusion process, the drying is carried out at 100 ℃ for 15 hours, and the roasting is carried out at 600 ℃ for 10 hours, so as to obtain the catalyst 1.
Example 2:
769.6 g of gamma-alumina powder and 35 g of polyethylene glycol (molecular weight 3000) powder are uniformly mixed, 60 g of calcium oxide powder, 30 g of magnesium oxide powder, 5 g of cerium oxide, 300 mg of manganese oxide and 100 mg of rhenium oxide powder are sequentially added into the mixture of the gamma-alumina powder and the polyethylene glycol, the mixture is uniformly stirred, a solution containing 100 g of alumina sol is added, the catalyst is formed by an extrusion process, the mixture is dried at 100 ℃ for 15 hours and is roasted at 600 ℃ for 10 hours, and the catalyst 2 is obtained.
Example 3:
uniformly mixing 500 g of gamma-alumina powder and 60 g of polyethylene glycol (molecular weight 4000), sequentially adding 60 g of calcium oxide powder, 60 g of magnesium oxide powder, 20 g of cerium oxide, 200 mg of manganese oxide and 150 mg of rhenium oxide powder into the mixture, uniformly stirring, adding a solution containing 300 g of aluminum sol, carrying out catalyst molding by an extrusion process, drying at 100 ℃ for 15 hours, and roasting at 600 ℃ for 10 hours to obtain a catalyst 3.
Example 4:
799.65 g of gamma-alumina powder and 20 g of polyethylene glycol (molecular weight of 6000) powder are uniformly mixed, then 40 g of calcium oxide powder, 30 g of magnesium oxide powder, 10 g of cerium oxide, 300 mg of manganese oxide and 50 mg of rhenium oxide powder are sequentially added into the mixture of the gamma-alumina powder and the polyethylene glycol, the mixture is uniformly stirred, then a solution containing 100 g of aluminum sol is added, the catalyst is formed by an extrusion process, the mixture is dried for 15 hours at 100 ℃, and the dried mixture is roasted for 10 hours at 600 ℃, so that the catalyst 4 is obtained.
The catalyst composition is shown in table 1.
TABLE 1 compositions of catalysts 1-4
Comparative example 1:
the conditions were identical to those of example 1 except that no manganese oxide powder was added, to give comparative catalyst 1.
Comparative example 2:
the conditions were identical to those of example 1, except that no rhenium oxide powder was added, giving comparative catalyst 2.
Comparative example 3:
the conditions were identical to those of example 1 except that no manganese oxide or rhenium oxide powder was added, giving comparative catalyst 3.
The comparative catalyst composition is shown in table 2.
TABLE 2 comparative catalysts 1-3 compositions
Preparation of methyl p-methoxycinnamate:
example 5:
296 g of methyl acetate, 80 g of methanol, 8.1 g of sodium methoxide solid and 92.5 g of 1, 3-dioxygen pentacyclic are added into a condensation reaction kettle, stirring and heat preservation are carried out at the reflux temperature for 0.2h, 68 g of p-methoxybenzaldehyde is added into the reaction kettle through a pipeline, simultaneously, a circulating pump is started to circulate reaction liquid through a reaction bed filled with 90.8 ml of catalyst 1, the circulation amount is 6.54 kg/h, the feeding time is 1h, the reflux and heat preservation are continued for 1h after the feeding is finished, water generated in the reaction process is timely removed through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device, and products are separated by cooling after the reaction is finished, so that 86.4 g of p-methoxycinnamic acid methyl ester (the yield is 90 wt%, the purity of the p-methoxy-3-p-methoxyphenylpropionic acid methyl ester is not detected) is obtained, and the purity is 99.78 wt%.
Example 6:
adding 222 g of methyl acetate, 240 g of methanol, 4.05 g of sodium methoxide solid and 333 g of 1, 3-dioxygen pentacyclic into a condensation reaction kettle, stirring and preserving heat for 0.5h at the reflux temperature, adding 68 g of p-methoxybenzaldehyde into the reaction kettle through a pipeline, starting a circulating pump to circulate reaction liquid through a reaction bed filled with 173.4 ml of catalyst 2, wherein the circulation amount is 7.43 kg/h, the feeding time is 1.2h, continuously refluxing and preserving heat for 1.5h after the feeding is finished, separating water generated in the reaction process through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device and timely removing the water, and cooling and separating the product after the reaction is finished to obtain 90.3 g of methyl p-methoxycinnamate (the yield is 94.1 wt%, the content of 3-methoxy-3-p-methoxyphenylpropionic acid methyl ester is not detected), and the purity is 99.75 wt%.
Example 7:
adding 222 g of methyl acetate, 160 g of methanol, 5.4 g of sodium methoxide solid and 148 g of 1, 3-dioxygen pentacyclic into a condensation reaction kettle, stirring and preserving heat for 0.2h at the reflux temperature, adding 68 g of p-methoxybenzaldehyde into the reaction kettle through a pipeline, starting a circulating pump to circulate reaction liquid through a reaction bed filled with 150.9 ml of catalyst 3, wherein the circulation amount is 3.62 kg/h, the feeding time is 1.5h, continuously refluxing and preserving heat for 1h after the feeding is finished, separating water generated in the reaction process through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device and timely removing the water, and cooling and separating products after the reaction is finished to obtain 89.3 g of methyl p-methoxycinnamate (the yield is 93 wt%, the purity of the methyl p-methoxyphenylpropionate containing 3-methoxy-3-p-methoxyphenylpropionate is not detected) and 99.68 wt%.
Example 8:
185 g of methyl acetate, 128 g of methanol, 8.1 g of sodium methoxide solid and 176 g of dioxane are added into a condensation reaction kettle, stirring and heat preservation are carried out at the reflux temperature for 0.6h, 68 g of p-anisaldehyde is added into the reaction kettle through a pipeline, meanwhile, a circulating pump is started to circulate reaction liquid through a reaction bed filled with 113 ml of catalyst 4, the circulating amount is 6.78 kg/h, the feeding time is 1h, the reflux and heat preservation are continued for 2h after the feeding is finished, water generated in the reaction process is separated and timely removed through a rectifying tower, a condensation heat exchanger and an inorganic pervaporation membrane device, and products are separated by cooling after the reaction is finished to obtain 85.4 g of p-anisic methyl cinnamate (the yield is 89 wt%, the content of 3-methoxy-3-p-anisic methyl propionate is not detected), and the purity is 99.80 wt%.
Example 9:
148 g of methyl acetate, 192 g of methanol, 8.1 g of sodium methoxide solid and 216 g of trioxane are added into a condensation reaction kettle, stirring and heat preservation are carried out for 1h at the reflux temperature, 68 g of p-methoxybenzaldehyde is added into the reaction kettle through a pipeline, meanwhile, a circulating pump is started to circulate reaction liquid through a reaction bed filled with 158 ml of catalyst 1, the circulating amount is 5.42 kg/h, the feeding time is 1.5h, the reflux and heat preservation are continued for 1h after the feeding is finished, water generated in the reaction process is separated and timely removed through a rectifying tower, a condensation heat exchanger and an inorganic pervaporation membrane device, and products are separated by cooling after the reaction is finished, so that 86.4 g of p-methoxy methyl cinnamate (the yield is 90 wt%, the content of 3-methoxy-3-p-methoxy phenyl methyl propionate is not detected) and the purity is 99.76 wt% is obtained.
Example 10:
adding 222 g of methyl acetate, 240 g of methanol, 6.75 g of sodium methoxide solid and 396 g of 1, 3-dioxane into a condensation reaction kettle, stirring and preserving heat for 0.8h at a reflux temperature, adding 68 g of p-methoxybenzaldehyde into the reaction kettle through a pipeline, starting a circulating pump to circulate reaction liquid through a reaction bed filled with 155.5 ml of catalyst 2, wherein the circulation amount is 5.6 kg/h, the feeding time is 1.3h, continuously refluxing and preserving heat for 3h after the feeding is finished, separating water generated in the reaction process through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device and timely removing the water, and cooling and separating a product after the reaction is finished to obtain 83.5 g of methyl p-methoxycinnamate (the yield is 87 wt%, the purity of the product is 99.73 wt%, and the content of the methyl 3-methoxy-3-p-methoxyphenyl propionate is not detected).
Example 11:
adding 74 g of methyl acetate, 80 g of methanol, 8.1 g of sodium methoxide solid and 92.5 g of 1, 3-dioxy pentacyclic into a condensation reaction kettle, stirring and preserving heat for 1h at the reflux temperature, adding 68 g of p-methoxybenzaldehyde into the reaction kettle through a pipeline, starting a circulating pump to circulate reaction liquid through a reaction bed filled with 64.5 ml of catalyst 3, wherein the circulating amount is 3.87 kg/h, the feeding time is 1.5h, continuously refluxing and preserving heat for 2h after the feeding is finished, separating water generated in the reaction process through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device, removing the water in time, and cooling and separating the product after the reaction is finished to obtain 81.6 g of p-methoxycinnamic acid methyl ester (the yield is 85 wt%, and the purity of 3-methoxy-3-p-methoxyphenylpropionic acid methyl ester is not detected) and 99.79 wt%.
Example 12:
adding 111 g of methyl acetate, 160 g of methanol, 4.05 g of sodium methoxide solid and 185 g of 1, 3-dioxygen pentacyclic into a condensation reaction kettle, stirring and preserving heat for 0.5h at a reflux temperature, adding 68 g of p-methoxybenzaldehyde into the reaction kettle through a pipeline, starting a circulating pump to circulate reaction liquid through a reaction bed filled with 132 ml of catalyst 4, wherein the circulation amount is 4.53 kg/h, the feeding time is 1.2h, continuously refluxing and preserving heat for 3h after the feeding is finished, separating water generated in the reaction process through a rectifying tower, a condensing heat exchanger and an inorganic pervaporation membrane device, removing the water in time, cooling and separating a product after the reaction is finished to obtain 84.5 g of methyl p-methoxycinnamate (the yield is 88 wt%, the purity is 99.85 wt%, and the content of the methyl 3-methoxy-3-p-methoxyphenylpropionate is not detected).
Comparative example 4:
the same procedure as in example 5 was repeated except that methanol was not added, to give 28.8 g of methyl p-methoxycinnamate (yield: 30% by weight, no methyl 3-methoxy-3-p-methoxyphenylpropionate contained therein) in a purity of 99.73% by weight.
Comparative example 5:
the same procedure as in example 5 was repeated except that the cyclic ether was not added, to give 62.4 g of methyl p-methoxycinnamate (yield 65% by weight, no methyl 3-methoxy-3-p-methoxyphenylpropionate contained therein) in a purity of 99.76% by weight.
Comparative example 6:
the same procedure as in example 5 was repeated except that water produced in the reaction was not removed, to obtain 19.2 g of methyl p-methoxycinnamate (yield: 20% by weight, no methyl 3-methoxy-3-p-methoxyphenylpropionate contained therein) in a purity of 99.78% by weight.
Comparative example 7:
the conditions were identical with those of example 5 except that the reaction mixture was not treated with a reaction bed, to give 69.2 g of methyl p-methoxycinnamate (yield: 72.1% by weight) and purity: 99.73% by weight, yielding 17.5 g of methyl 3-methoxy-3-p-methoxyphenylpropionate.
Comparative example 8:
the conditions were identical to those of example 5 except that catalyst 1 was replaced with comparative catalyst 1, to give 78.7 g of methyl p-methoxycinnamate (yield 82% by weight), purity 99.75% by weight, and to give 10 g of methyl 3-methoxy-3-p-methoxyphenylpropionate.
Comparative example 9:
the conditions were identical to those in example 5 except that the catalyst 1 was replaced with the comparative catalyst 2, to give 76.8 g of methyl p-methoxycinnamate (yield 80% by weight) with a purity of 99.73% by weight, giving 11 g of methyl 3-methoxy-3-p-methoxyphenylpropionate.
Comparative example 10:
the conditions were identical to those in example 5 except that the catalyst 1 was replaced with the comparative catalyst 3, to give 73 g of methyl p-methoxycinnamate (yield 76% by weight), purity 99.77% by weight, and 13.5 g of methyl 3-methoxy-3-p-methoxyphenylpropionate.
Comparative example 11:
the same procedures used in example 5 were repeated except for replacing 1, 3-dioxolane with tetrahydrofuran (90 g) in an equimolar ratio to give 67.2 g of methyl p-methoxycinnamate (yield: 70% by weight, no methyl 3-methoxy-3-p-methoxyphenylpropionate contained therein was detected) in a purity of 99.78% by weight.
Finally, it should be noted that the above-mentioned embodiments only illustrate the preferred embodiments of the present invention, and do not limit the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that various changes and modifications can be made by modifying the technical solution of the present invention or equivalent substitutions within the scope of the present invention defined by the claims.
Claims (14)
1. A preparation method of methyl p-methoxycinnamate comprises the following steps:
a) adding methyl acetate, methanol, sodium methoxide and cyclic ether into a condensation reaction kettle, stirring at a reflux temperature, and keeping the temperature for 0.2-1 h;
b) adding p-methoxybenzaldehyde into a condensation reaction kettle, circulating a reaction solution through a reaction bed filled with a catalyst, carrying out reflux heat preservation after the p-methoxybenzaldehyde is added, continuing to react for 0.5-5 h, and separating and removing water generated in the reaction process through a rectifying tower, a condensation heat exchanger and an inorganic pervaporation membrane device; the cyclic ether in step a) is selected from one or more of dioxane, trioxane, 1, 3-dioxane and 1, 3-dioxolane; the composition of the catalyst filled in the reaction bed in the step b) is as follows: calculated by the total weight of the materials, 53.1-81.6% of gamma-alumina, 3.2-6.4% of calcium oxide, 3-6.5% of magnesium oxide, 0.5-2.2% of cerium oxide, 50-500 ppm of manganese oxide, 30-400 ppm of rhenium oxide and 10.2-32.3% of alumina sol.
2. The method according to claim 1, wherein the molar ratio of methyl acetate to p-methoxybenzaldehyde in step a) is 1.1-10: 1.
3. The method according to claim 1, wherein the molar ratio of methyl acetate to p-methoxybenzaldehyde in step a) is 2-8: 1.
4. The method according to claim 1, wherein the molar ratio of methanol to p-methoxybenzaldehyde in step a) is 2-100: 1.
5. The method according to claim 1, wherein the molar ratio of methanol to p-methoxybenzaldehyde in step a) is 5-15: 1.
6. The process according to claim 1, wherein the molar ratio of cyclic ether to methanol in step a) is 0.2 to 1: 1.
7. The process according to claim 1, wherein the molar ratio of cyclic ether to methanol in step a) is 0.4 to 0.6: 1.
8. The method as claimed in claim 1, wherein the packing volume of the catalyst in the reaction bed in the step b) is 1/10-1/3 of the total volume of the materials added into the condensation reaction kettle.
9. The method as claimed in claim 1, wherein the packing volume of the catalyst in the reaction bed in the step b) is 1/6-1/4 of the total volume of the materials added into the condensation reaction kettle.
10. The method as claimed in claim 1, wherein the circulation flow rate of the reaction solution in the step b) is such that the reaction solution is circulated every 5 to 10 minutes.
11. The method as claimed in claim 1, wherein the composition of the catalyst packed in the reaction bed in the step b) is as follows: calculated by the total weight of all the substances, 53.1-81.6% of gamma-alumina, 3.2-6.4% of calcium oxide, 3-6.5% of magnesium oxide, 0.5-2.2% of cerium oxide, 105-315 ppm of manganese oxide, 50-215 ppm of rhenium oxide and 10.2-32.3% of alumina sol.
12. The method according to claim 1, wherein the mass ratio of the manganese oxide to the rhenium oxide is 0.3 to 10.
13. The method according to claim 1, wherein the mass ratio of the manganese oxide to the rhenium oxide is 0.5 to 6.
14. The method according to claim 1, wherein the preparation method of the catalyst in the step b) comprises the following steps:
1) uniformly mixing gamma-alumina and polyethylene glycol; then adding calcium oxide, magnesium oxide, cerium oxide, manganese oxide and rhenium oxide into the mixture, and uniformly mixing;
2) adding alumina sol into the mixture obtained in the step 1), forming, drying and roasting to obtain the catalyst.
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|---|---|---|---|---|
| KR950017906A (en) * | 1993-12-20 | 1995-07-20 | 하기주 | Manufacturing method of liquid ultraviolet stabilizer |
| CN1170401A (en) * | 1994-12-19 | 1998-01-14 | Isp凡·戴克股份有限公司 | Preparation of cinnamate sunscreen agents |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR950017906A (en) * | 1993-12-20 | 1995-07-20 | 하기주 | Manufacturing method of liquid ultraviolet stabilizer |
| CN1170401A (en) * | 1994-12-19 | 1998-01-14 | Isp凡·戴克股份有限公司 | Preparation of cinnamate sunscreen agents |
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| Title |
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| 《An efficient method for synthesis of 2-ethylhexyl 4-ethoxycinnamate：a raw material for the cosmetics industry》;Vasanti G. Yadav和S B Chandalia;《Indian Journal of Chemical Technology 》;19990131;第6卷(第1期);第19-23页 * |
| 《对甲氧基肉桂酸正丁酯的合成》;邢彦美等;《精细石油化工》;20100415;第27卷(第2期);第68-71页 * |
| 《对甲氧基肉桂酸甲酯的合成》;邢彦美等;《青岛科技大学学报(自然科学版)》;20100415;第31卷(第2期);第141-143、161页 * |
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