Method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicalite

Abstract

The invention discloses a method for synthesizing p-hydroxyanisole by catalyzing anisole oxidation by TS-1 titanium silicon molecular sieve, which comprises the following steps: 1) anisole, acetonitrile, tert-butyl alcohol, TS-1 titanium silicon molecular sieve are added to a reaction vessel, and the reaction is stirred at 45-55°C under temperature control; 2) TS-1 titanium silicon molecular sieve is filtered; temperature control is 0-10°C, and a reducing agent is added to quench the oxidizability; dry tert-butyl alcohol and acetonitrile are concentrated; organic solvent extraction is used; washing; dry organic phase is concentrated; 3) vacuum decompression distillation is performed, and fractions are collected to obtain a product. The present invention utilizes relatively low-priced anisole as a raw material, and TS-1 titanium silicon molecular sieve catalyst is used as a core to cause the production of p-hydroxyanisole without black oil in the reaction, and acetonitrile and tert-butyl alcohol solvents bring the p-hydroxyanisole yield to 93%, and the selectivity is as high as 97%, which greatly improves the selectivity and conversion rate of the reaction, reduces the impact of black oil on the reaction system and the recycling of the catalyst, and has the characteristics of simple process, high yield and good quality.

Description

Technical Field

[0001] The invention relates to a method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicon molecular sieve, and belongs to the technical field of organic synthesis. Background Art

[0002] p-Hydroxyanisole, also known as p-methoxyphenol, hydroquinone monomethyl ether, white flakes or waxy crystals, molecular formula: C7H802, molecular weight: 124.14, CAS number: 150-76-5, melting point 52.5℃ (55-57℃), boiling point 243℃, relative density 1.55 (20 / 20℃). It is easily soluble in ethanol, ether, acetone, benzene and ethyl acetate, and slightly soluble in water. The biggest advantage of this product is that the monomer after adding MEHQ does not need to be removed when copolymerizing with other monomers, and can be directly copolymerized by ternary. It is not only used as an inhibitor for vinyl plastic monomers, UV inhibitors, dye intermediates, and for the synthesis of edible oils and cosmetic antioxidants BHA, but also an important intermediate for fine chemical products such as medicines, spices, pesticides, etc., and has a wide range of uses.

[0003] The p-hydroxyanisole synthetic method mainly contains anisole method, hydroquinone method and benzaldehyde method. At present, mainly with hydroquinone method and p-aminoanisole diazotization method at home and abroad, wherein the hydroquinone method adopts dimethyl sulfate, and this method has the disadvantages of being highly toxic, foul smell, and low yield of product that is easy to pollute the environment, and the methanol catalysis method has the same problem of three wastes pollution and serious equipment corrosion in the production process as the p-aminoanisole diazotization method. The method that existing anisole is oxidized to p-hydroxyanisole has the following problems:

[0004] 1. Black tar polymers appear in the copper salt catalytic oxidation system, which seriously affects the product yield and purification effect. The catalyst is difficult to recover and reuse;

[0005] 2. The conversion rate and selectivity of the anisole reaction under a single solvent are low, and efficient selection cannot be achieved. Many side reactions occur, such as oxidation to synthesize o-hydroxyanisole and coupling reactions between products. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a method for synthesizing p-hydroxyanisole by oxidizing anisole with TS-1 titanium silicalite catalyzed by acetonitrile and tert-butyl alcohol, and the yield and selectivity are improved. The synthesis method is green and clean, and the process is simple. The catalyst reduces black tar pollution and can be reused, thus saving costs.

[0007] To achieve the above object, the technical solution of the present invention is:

[0008] The method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicalite comprises the following steps:

[0009] (1) Add anisole, acetonitrile, tert-butyl alcohol, TS-1 titanium silicalite molecular sieve, and oxidant into a reaction vessel, control the temperature at 45-55°C, and stir to react for 6-10 hours;

[0010] Wherein, the volume ratio of anisole to acetonitrile is 1:1-5, the volume ratio of acetonitrile to tert-butyl alcohol is 6-10:1, and the mass ratio of anisole to TS-1 titanium silicalite molecular sieve is 1:0.05-0.2;

[0011] In this step, the reaction is carried out under a nitrogen atmosphere;

[0012] Specifically, the oxidant is hydrogen peroxide, the hydrogen peroxide is 35% hydrogen peroxide, and the molar ratio of anisole to 35% hydrogen peroxide is 1:1.2~2.

[0013] (2) After the reaction is completed, cool to room temperature, filter TS-1 titanium silicalite; control the temperature at 0-10°C, add a reducing agent to quench the oxidative property; concentrate tert-butanol and acetonitrile; extract with an organic solvent; wash; and concentrate the organic phase;

[0014] Specifically, the concentration is performed by spin drying or vacuum pump reduced pressure distillation;

[0015] Specifically, in this step, the reducing agent is sodium sulfite, the organic solvent is dichloromethane, and saturated brine is added for washing.

[0016] (3) Perform reduced pressure distillation at a vacuum degree below 0.53 kPa and collect the fraction at 110-130 °C.

[0017] By adopting the synthesis method of the present invention, the conversion rate of anisole is 80-97%, the selectivity is 90-97%, and the GC purity of the product is above 99%.

[0018] Reaction equation:

[0019] 1. Main oxidation reaction:

[0020]

[0021] 2. Side oxidation reaction:

[0022]

[0023] 3. Side coupling reaction

[0024]

[0025] Compared with the prior art, the synthesis method of the present invention has the following advantages:

[0026] 1. The method of synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicalite molecular sieve uses TS-1 titanium silicalite molecular sieve catalyst to reduce the black tar produced by the product coupling reaction in the oxidation reaction system, thereby improving the yield and reducing the steps of removing the black tar, making the purification process simple and convenient.

[0027] 2. The method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicalite selects acetonitrile and tert-butanol as system solvents, wherein the ratio of acetonitrile to tert-butanol changes, and the selectivity of the corresponding anisole also changes accordingly. The combination of the two is biased towards p-hydroxyanisole to improve the selectivity of the desired product compared with a single solvent, while a single solvent will produce more 2-o-hydroxyanisole.

[0028]

[0029] The invention uses relatively low-priced anisole as a raw material and takes a TS-1 titanium silicon molecular sieve catalyst as a core, so that no black oil exists in the reaction of producing p-hydroxyanisole. Acetonitrile and tert-butyl alcohol solvents increase the yield of p-hydroxyanisole to 93%, and the selectivity is as high as 97%, which greatly improves the selectivity and conversion rate of the reaction, reduces the influence of black oil on the reaction system and the recycling of the catalyst, and has the characteristics of simple process, high yield, good quality and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0031] Figure 1 The HPLC detection chromatogram of the crude product obtained in Example 1.

[0032] Figure 2 The HPLC detection chromatogram of the product obtained in Example 1.

[0033] Figure 3 The HPLC detection chromatogram of the crude product obtained for Example 2.

[0034] Figure 4 The HPLC detection chromatogram of the product obtained in Example 2.

[0035] Figure 5 The HPLC detection chromatogram of the crude product obtained for Example 3.

[0036] Figure 6 The HPLC detection chromatogram of the product obtained in Example 3. DETAILED DESCRIPTION

[0037] In the following implementation, the materials are (name / manufacturer / model): anisole / Shanghai McLean Biochemical Technology Co., Ltd. / Lot#: C15959995, TS-1 titanium silicalite / Jiangsu Xianfeng Nanomaterial Technology Co., Ltd. / 330001, 35% hydrogen peroxide / commercially available, acetonitrile / Tianchen Qixiang New Materials Co., Ltd. / CPO2202312002, tert-butyl alcohol / Beijing Tianyu Kanghong Chemical Technology Co., Ltd. / TY20230106, dichloromethane / Shandong Jinling Chemical Co., Ltd. / 22040227.

[0038] Example 1

[0039] In a 100 ml reaction container, add 10 g (0.09 mol) of anisole, 10 mL of acetonitrile, 1 mL of tert-butyl alcohol, and 0.5 g of TS-1 titanium silicalite molecular sieve. Heat the system to 50 °C, add 10.78 g (0.11 mol) of 35% hydrogen peroxide, control the temperature at 50 °C, and stir the reaction under nitrogen atmosphere for 8 h.

[0040] Cool to room temperature and filter the molecular sieve. After controlling the temperature to 0-10°C, use sodium sulfite solution to quench the oxidation. After drying tert-butyl alcohol and acetonitrile, extract twice with 50 mL (5 Vol) of dichloromethane. Add saturated brine to wash once. Dry the organic phase to obtain the crude product. The crude product is tested and the HPLC test chromatogram of the crude product is as follows: Figure 1 As shown;

[0041] The crude product was distilled under reduced pressure at a vacuum degree of less than 0.53 kpa, and the fraction at 110-130°C was collected. The fraction had an HPLC purity of 99.84%. The conversion rate of anisole was 89%, and the selectivity was 97%. The obtained product was tested, and the HPLC test chromatogram of the product was obtained as shown in FIG. Figure 2 shown.

[0042] Example 2

[0043] In a 100 ml reaction vessel, 10 g (0.09 mol) of anisole, 50 mL of acetonitrile, 5 mL of tert-butyl alcohol, and 2 g of TS-1 titanium silicalite were added. The system was heated to 50 °C, 17.97 g (0.18 mol) of 35% hydrogen peroxide was added, the temperature was controlled at 50 °C, and the reaction was stirred for 8 h under a nitrogen atmosphere.

[0044] Cool to room temperature and filter the molecular sieve. After controlling the temperature to 0-10°C, use sodium sulfite solution to quench the oxidation. After drying tert-butyl alcohol and acetonitrile, extract twice with 100 mL (10 Vol) of dichloromethane. Add saturated brine to wash once. Dry the organic phase to obtain the crude product. The crude product is tested and the HPLC test chromatogram of the crude product is as follows: Figure 3 As shown;

[0045] The crude product was distilled under reduced pressure at a vacuum degree of less than 0.53 kpa, and the fraction at 110-130°C was collected. The fraction had an HPLC purity of 99.92%. The conversion rate of anisole was 93%, and the selectivity was 97%. The obtained product was tested, and the HPLC test chromatogram of the product was obtained as shown in FIG. Figure 4 shown.

[0046] Example 3

[0047] In a 250 ml reaction vessel, add 50 g (0.46 mol) of anisole, 150 mL of acetonitrile, 30 mL of tert-butyl alcohol, and 5 g of TS-1 titanium silicalite molecular sieve. Heat the system to 50 °C, add 71.86 g (0.74 mol) of 35% hydrogen peroxide, control the temperature at 45-55 °C, and react under nitrogen atmosphere with stirring for 8 h.

[0048] Cool to room temperature and filter the molecular sieve. Control the temperature to 0-10°C and then use sodium sulfite solution to quench the oxidation. After drying tert-butyl alcohol and acetonitrile, extract twice with 400mL (8 Vol) dichloromethane, add saturated brine to wash once, and dry the organic phase to obtain the crude product. The obtained crude product is tested and the HPLC test chromatogram of the crude product is as follows: Figure 5 As shown;

[0049] The crude product was distilled under reduced pressure at a vacuum degree of less than 0.53 kpa, and the fraction at 110-130°C was collected. The fraction had an HPLC purity of 99.93%. The conversion rate of anisole was 97%, and the selectivity was 97%. The obtained product was tested, and the HPLC test chromatogram of the product was obtained as shown in FIG. Figure 6 shown.

[0050] The above embodiments do not limit the present invention in any way, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicalite, characterized in that: The following steps are involved: (1) Add anisole, acetonitrile, tert-butanol, TS-1 titanium silicalite molecular sieve, and an oxidant into a reaction vessel, and stir to react at a temperature of 45 to 55° C.; wherein the volume ratio of anisole to acetonitrile is 1:1 to 5, and the volume ratio of acetonitrile to tert-butanol is 6 to 10:1; (2) Filter TS-1 titanium silicalite; control the temperature at 0-10°C, add a reducing agent to quench the oxidative property; concentrate tert-butanol and acetonitrile; extract with an organic solvent; wash; concentrate the organic phase; (3) Vacuum distillation and collecting fractions; In the step (1), the oxidant is hydrogen peroxide; In the step (2), the reducing agent is sodium sulfite, the organic solvent is dichloromethane, and the volume ratio of anisole to dichloromethane is 1:5-10.

2. The method for synthesizing p-hydroxyanisole by catalyzing the oxidation of anisole by TS-1 titanium silicon molecular sieve according to claim 1, characterized in that: In the step (1), the reaction is carried out under a nitrogen atmosphere.

3. The method for synthesizing p-hydroxyanisole by catalyzing the oxidation of anisole by TS-1 titanium silicon molecular sieve according to claim 1, characterized in that: In the step (1), the mass ratio of anisole to TS-1 titanium silicalite molecular sieve is 1:0.05-0.

2.

4. The method for synthesizing p-hydroxyanisole by oxidative oxidation of anisole catalyzed by TS-1 titanium silicon molecular sieve according to claim 1, characterized in that: The hydrogen peroxide is 35% hydrogen peroxide.

5. The method for synthesizing p-hydroxyanisole by oxidative oxidation of anisole catalyzed by TS-1 titanium silicon molecular sieve according to claim 4, characterized in that: The molar ratio of anisole to hydrogen peroxide is 1:1.2-2.

6. The method for synthesizing p-hydroxyanisole by oxidation of anisole catalyzed by TS-1 titanium silicon molecular sieve according to claim 1, characterized in that: In the step (2), saturated brine is added for washing.

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