WO2020238189A1

WO2020238189A1 - Preparation method of antioxidant 3,5-methyl ester

Info

Publication number: WO2020238189A1
Application number: PCT/CN2019/128315
Authority: WO
Inventors: 郭骄阳; 赵崇鑫
Original assignee: 江苏极易新材料有限公司
Priority date: 2019-05-31
Filing date: 2019-12-25
Publication date: 2020-12-03
Also published as: CN110092717B; CN110092717A

Abstract

Disclosed is a preparation method of an antioxidant 3,5-methyl ester, comprising the following steps: preparation of a catalyst and preparation of the antioxidant 3,5-methyl ester. Using methyl 3-(4-hydroxyphenyl)propionate as raw material, an alkylation reaction with tert-butanol is performed under the action of a catalyst and under microwave conditions so as to obtain the antioxidant 3,5-methyl ester. The present invention uses readily-available, low-cost clay to produce a novel reusable catalyst, avoiding wastage of catalyst. By using methyl 3-(4-hydroxyphenyl)propionate and tert-butanol as raw materials, a self-polymerization side reaction of the raw materials is avoided. The antioxidant 3,5-methyl ester prepared therefrom has high yield and excellent quality.

Description

A kind of preparation method of antioxidant 3,5-methyl ester

Technical field

The invention relates to the technical field of fine chemicals, in particular to a preparation method of antioxidant 3,5-methyl ester.

Background technique

Antioxidants have good oxidation resistance, stable oxidation stability and thermal stability, good compatibility with polymers, extremely low volatility, and are not easy to lose due to volatilization at high temperatures. It can effectively prevent the damage of light, heat and oxygen to the polymer, and significantly improve the performance of the polymer; delay or prevent the oxidation or automatic oxidation process of synthetic materials, thereby prolonging the service life of the material, without pollution and coloring. It can be widely used in general plastics, engineering plastics, synthetic rubber, fiber, resin, ink, coating and other industries, and its application involves almost all polymer products. Polyphenol antioxidants 1010 and 1076 are currently the leading products of excellent antioxidants, and their consumption accounts for about 40% of the total consumption of antioxidants.

Antioxidant 3,5-methyl ester is a good hindered phenolic antioxidant. It has good anti-aging function for polyethylene, polypropylene, polyvinyl chloride and other plastics, animal oil, rubber and other organic polymer compounds. . In addition, the antioxidant 3,5-methyl ester is not only the main intermediate for the production of antioxidant 1010, but also the main intermediate for the production of high-end antioxidants such as antioxidants 259, 697, 1024, 1035, 1076, 1098 and 3125. . The existing antioxidant 3,5-methyl ester preparation method uses 2,6-di-tert-butylphenol and methyl acrylate as raw materials and potassium tert-butoxide as a catalyst to prepare antioxidants under certain temperature conditions 3,5-Methyl ester. In this process, the use of potassium tert-butoxide increases the production cost; and due to the limitation of catalyst activity conditions, the reaction temperature needs to be controlled between 80-130°C. Under this temperature condition, methyl acrylate is prone to self-polymerization and formation Dimer or multimer, the dimer reacts with 2,6-di-tert-butylphenol to generate diester, which increases by-products, thereby affecting the quality and yield of antioxidant 3,5-methyl; To make 2,6-di-tert-butylphenol fully react, use excessive methyl acrylate, which undoubtedly increases the possibility of side reactions and production costs, and affects the quality and quality of antioxidant 3,5-methyl ester Yield.

Therefore, in order to reduce the production cost and avoid the self-polymerization of methyl acrylate, it is of positive significance to invent a new type of catalyst using methyl p-hydroxyphenylpropionate to prepare the antioxidant 3,5-methyl ester.

Summary of the invention

The purpose of the present invention is to shorten the reaction time, reduce the occurrence of side reactions, reduce production costs, and increase the yield of antioxidant 3,5-methyl ester during the process of preparing antioxidant 3,5-methyl ester. quality.

In order to achieve the above objective, the present invention provides the following technical solution, a preparation method of antioxidant 3,5-methyl ester, using methyl p-hydroxyphenylpropionate as a raw material, pretreated clay as a catalyst, under microwave conditions Next, carry out alkylation reaction with tert-butanol to obtain antioxidant 3,5-methyl ester.

According to the above technical scheme, the specific steps are:

(1) Preparation of the catalyst: take the clay, mix the clay with a certain concentration of p-toluenesulfonic acid aqueous solution under microwave radiation, and then centrifuge the mixture and wash it with distilled warm water for at least three times. Until the centrifuged water is neutral. The treated clay is dried under certain microwave conditions and then ground into fine powder to obtain the pretreated clay, which is used as a catalyst for later use.

(2) Preparation of antioxidant 3,5-methyl ester: add methyl p-hydroxyphenylpropionate, tert-butanol and catalyst to the reactor vessel, and irradiate the reaction mixture under microwave for alkylation reaction, and the reaction is completed After cooling the sample, the catalyst was filtered out, and extracted with cyclohexanol to obtain the antioxidant 3,5-methyl ester.

The particle size of the above clay is 100-200 mesh.

The above-mentioned novel catalyst is pretreated clay, and its dosage is 0.47-0.71 times the weight of tert-butanol.

The above-mentioned pretreated clay is obtained by treating the clay with an aqueous solution of p-toluenesulfonic acid.

The concentration of the above-mentioned p-toluenesulfonic acid aqueous solution is 0.1-1.0M.

In the preparation of the above catalyst, the microwave power is 500-1000W, the microwave temperature is 373K, the heating time is 4-6h, and the particle size is 75-100 μm.

The molar ratio of the methyl p-hydroxyphenylpropionate to the tert-butanol is 1:2 to 1:3, and more preferably, the molar ratio of the methyl p-hydroxyphenylpropionate to the tert-butanol is 1:2.5.

The alkylation reaction time is 2-6h; the microwave temperature of the alkylation reaction is 373-473K.

The reactor used in the experiment is equipped with a PTFE-coated magnetic stirring rod, and the outer layer is equipped with a ring-shaped condensation device.

Compared with the prior art, the beneficial effect of the present invention is: a new process for preparing the antioxidant 3,5-methyl ester by using methyl p-hydroxyphenylpropionate by using a new type of catalyst Ester and tert-butanol are used as raw materials to avoid the side reactions of the raw materials themselves; the microwave reaction conditions are used to shorten the reaction time; clay is a generally available and low-cost substance, which reduces the cost of raw materials for the reaction; Clay is a catalyst, which can be used repeatedly to reduce the waste of catalyst; the antioxidant 3,5-methyl ester prepared by this method has a high yield and excellent quality.

Description of the drawings

Figure 1 is the preparation chemical reaction formula of the antioxidant 3,5-methyl ester of the present invention.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.

The chemical composition of the clay used in the following examples is 50.83% SiO ₂ , 5.90% Al ₂ O ₃ , 1.13% CaO, 9.94% Fe ₂ O ₃ , 0.090% K ₂ O, 0.734% MgO, 3.77% Na ₂ O, 0.11 %P ₂ O ₅ and 0.714%TiO ₂ .

Example 1:

Preparation of the catalyst: Take 1g of 100 mesh clay and add it to a microwave stirring vessel. Under the conditions of a microwave power of 500-1000W and a microwave temperature of 323K, turn on the magnetic stirring, and mix the clay evenly with a 0.1M p-toluenesulfonic acid aqueous solution After 4 hours of treatment, after the clay and the p-toluenesulfonic acid aqueous solution are evenly mixed, the mixture is centrifuged on a centrifugal machine and washed with distilled warm water for three times until the centrifugal water is neutral. The centrifuged clay was dried under 373K microwave conditions for 2 hours, and then ground into a fine powder with a particle size of 75 μm to obtain a catalyst.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 2.8g (40mmol) of tert-butanol and 1.3g of catalyst into the reactor vessel, turn on the magnetic stirring, and make stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried with anhydrous sodium sulfate, concentrated and spin-dried for purification to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 84.6%, and the purity of the antioxidant 3,5-methyl ester was 80.1%.

Example 2:

Preparation of the catalyst: Take 1g of 100 mesh clay and add it to a microwave stirring vessel. Under the conditions of a microwave power of 500-1000W and a microwave temperature of 323K, turn on magnetic stirring, and treat the clay with 0.2M p-toluenesulfonic acid aqueous solution for 4h After the clay and the p-toluenesulfonic acid aqueous solution are evenly mixed, the mixture is centrifuged on a centrifugal machine and washed with distilled warm water for three times until the centrifugal water is neutral. The centrifuged clay was dried under 373K microwave conditions for 2 hours, and then ground into a fine powder with a particle size of 75 μm to obtain a catalyst.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 2.8g (40mmol) of tert-butanol and 1.3g of catalyst into the reactor vessel, turn on the magnetic stirring, and make stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 85.9%, and the purity of the antioxidant 3,5-methyl ester was 81.6%.

Example 3:

Preparation of the catalyst: Take 1g of 100 mesh clay and add it to a microwave stirring vessel. Under the conditions of a microwave power of 500-1000W and a microwave temperature of 323K, turn on magnetic stirring, and treat the clay with a 0.5M p-toluenesulfonic acid aqueous solution. After the clay and the p-toluenesulfonic acid aqueous solution are evenly mixed, the mixture is centrifuged on a centrifuge and washed with distilled warm water for three times until the centrifuged water is neutral. The centrifuged clay was dried under 373K microwave conditions for 2 hours, and then ground into a fine powder with a particle size of 75 μm to obtain a catalyst.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 2.8g (40mmol) of tert-butanol and 1.3g of catalyst into the reactor vessel, turn on the magnetic stirring, and make stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 87.8%, and the purity of the antioxidant 3,5-methyl ester was 84.5%.

Example 4:

Preparation of the catalyst: Take 1g of 100 mesh clay and add it to a microwave stirring vessel. Under the conditions of microwave power of 500-1000W and microwave temperature of 323K, turn on magnetic stirring, and treat the clay with 1.0M p-toluenesulfonic acid aqueous solution. After the clay and the p-toluenesulfonic acid aqueous solution are evenly mixed, the mixture is centrifuged on a centrifuge and washed with distilled warm water for three times until the centrifuged water is neutral. The resulting centrifuged clay was dried under 373K microwave conditions for 2 hours, and then ground into a fine powder with a particle diameter of 75 μm to obtain a catalyst.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 2.8g (40mmol) of tert-butanol and 1.3g of catalyst into the reactor vessel, turn on the magnetic stirring, and make stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 88.0%, and the purity of the antioxidant 3,5-methyl ester was 84.3%.

Example 5:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.3g of catalyst to the reactor vessel, turn on the magnetic stirring, and stir The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 90.1%, and the purity of the antioxidant 3,5-methyl ester was 90.0%.

Example 6:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 4.2g (60mmol) of tert-butanol and 1.3g of catalyst to the reactor vessel, turn on the magnetic stirring, and stir The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 90.6%, and the purity of the antioxidant 3,5-methyl ester was 90.1%.

Example 7:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 93.4%, and the purity of the antioxidant 3,5-methyl ester was 93.1%.

Example 8:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.9g of catalyst into the reactor vessel, turn on the magnetic stirring, and stir The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 2h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 95.0%, and the purity of the antioxidant 3,5-methyl ester was 93.1%.

Example 9:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 99.2%, and the purity of the antioxidant 3,5-methyl ester was 98.7%.

Example 10:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes. After the mixing is uniform, the microwave heating device is turned on, and the reaction mixture is microwaved at 423K for 6 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 98.9%, and the purity of the antioxidant 3,5-methyl ester was 98.6%.

Example 11:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, so that the reaction mixture is microwaved at 373K for 4h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 81.4%, and the purity of the antioxidant 3,5-methyl ester was 75.6%.

Example 12:

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 473K for 4h. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 99.7%, and the purity of the antioxidant 3,5-methyl ester was 98.2%.

Example 13:

The catalyst filtered off after the reaction in Example 9 was used and dried as the catalyst of Example 13.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 98.1%, and the purity of the antioxidant 3,5-methyl ester was 98.0%.

Example 14:

The catalyst filtered off after the reaction in Example 13 was used and dried as the catalyst of Example 14.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 98.0%, and the purity of the antioxidant 3,5-methyl ester was 98.0%.

Example 15:

The catalyst filtered out after the reaction in Example 14 was used and dried as the catalyst of Example 15.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 97.8%, and the purity of the antioxidant 3,5-methyl ester was 97.9%.

Example 16:

The catalyst filtered off after the reaction in Example 15 was used and dried as the catalyst of Example 16.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 97.9%, and the purity of the antioxidant 3,5-methyl ester was 97.6%.

Example 17:

The catalyst filtered off after the reaction in Example 16 was used and dried as the catalyst of Example 17.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 97.5%, and the purity of the antioxidant 3,5-methyl ester was 97.4%.

Example 18:

The catalyst filtered off after the reaction in Example 17 was used and dried as the catalyst of Example 18.

Preparation of antioxidant 3,5-methyl ester: Add 2g (20mmol) of methyl p-hydroxyphenylpropionate, 3.5g (50mmol) of tert-butanol and 1.6g of catalyst into the reactor vessel, turn on the magnetic stirring, and make the stirring The speed is controlled at 500r/min, and the raw materials and the catalyst are mixed uniformly by pre-stirring for 10 minutes, and the microwave heating device is turned on after the mixing is uniform, and the reaction mixture is microwaved at 423K for 4 hours. After the reaction was completed, the condensing device was turned on to cool the reaction mixture, and the mixture was extracted with 10 mL of cyclohexanol, and the catalyst was filtered out. The organic phase obtained by extraction is dried over anhydrous sodium sulfate and then concentrated and spin-dried to obtain antioxidant 3,5-methyl ester. Among them, the reaction mixture was sampled and quantitatively analyzed by gas chromatography. The conversion rate of methyl p-hydroxyphenylpropionate was 97.1%, and the purity of the antioxidant 3,5-methyl ester was 97.0%.

It can be seen from the experimental data that the catalytic effect obtained by treating the clay with 0.5M p-toluenesulfonic acid aqueous solution is better (see Example 1-4); the increase in the amount of the reactant tert-butanol in the experiment has little effect on the reaction (See Examples 3, 5, 6); The amount of catalyst used in the experiment has a certain effect on the conversion rate of methyl p-hydroxyphenylpropionate, but the purity of the antioxidant 3,5-methyl has little effect (see Example 5, 7, 8); With the extension of the reaction time, the conversion rate of methyl p-hydroxyphenylpropionate and the purity of the antioxidant 3,5-methyl ester can be increased. When the reaction time reaches 4h, the reaction The increase of time has little effect on the product (see Examples 7, 9, 10); the decrease of microwave temperature affects the progress of the reaction, and the increase of microwave temperature has little effect on the product yield (see Examples 7, 11, 12); The use of recycled catalysts for the preparation of antioxidant 3,5-methyl ester has little effect on the results (see Examples 13-18).

Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. Alternatives and modifications, the scope of the present invention is defined by the appended claims and their equivalents.

Claims

A preparation method of antioxidant 3,5-methyl ester is characterized in that it comprises the following steps:

(1) Preparation of the catalyst: take the clay, mix the clay with a certain concentration of p-toluenesulfonic acid aqueous solution under microwave radiation, and then centrifuge the mixture and wash it with distilled warm water for at least three times. Until the centrifugal water is neutral; after microwave treatment, the treated clay is ground into fine powder, and the pretreated clay is obtained as a catalyst for later use;

(2) Preparation of antioxidant 3,5-methyl ester: add methyl p-hydroxyphenylpropionate, tert-butanol and a new type of catalyst into the reactor vessel, and irradiate the reaction mixture under microwaves for alkylation reaction. After completion, the sample was cooled, the catalyst was filtered, and extracted with cyclohexanol to obtain the antioxidant 3,5-methyl ester.
The method for preparing antioxidant 3,5-methyl ester according to claim 1, wherein the particle size of the clay selected in the step (1) is 100-200 mesh.
The method for preparing an antioxidant 3,5-methyl ester according to claim 1, characterized in that the amount of catalyst in the step (2) is 0.47-0.71 times the weight of tert-butanol.
The method for preparing antioxidant 3,5-methyl ester according to claim 1, wherein the concentration of the p-toluenesulfonic acid aqueous solution is 0.1-1.0M.
The method for preparing antioxidant 3,5-methyl ester according to claim 1, wherein the microwave power is 500-1000W, the microwave temperature is 373K, and the heating time is 4-6h in the preparation of the catalyst. , The particle size is 75-100μm.
The method for preparing an antioxidant 3,5-methyl ester according to claim 1, wherein the molar ratio of the methyl p-hydroxyphenylpropionate to tert-butanol is 1:2-1: 3.
The method for preparing antioxidant 3,5-methyl ester according to claim 7, wherein the molar ratio of the methyl p-hydroxyphenylpropionate to tert-butanol is 1:2.5.
The method for preparing an antioxidant 3,5-methyl ester according to claim 1, wherein the alkylation reaction time is 2-6 hours.
The method for preparing antioxidant 3,5-methyl ester according to claim 1, wherein the microwave temperature of the alkylation reaction is 373-473K.