Method for preparing p-isopropenylphenol

Abstract

The invention provides a method for preparing p-isopropenylphenol, which is characterized by comprising the following steps: S1, carrying out nucleophilic addition reaction on 4-hydroxyacetophenone and a tetrahydrofuran solution of alkyl magnesium halide in a solvent 1 to obtain 4-(2-hydroxypropyl-2-yl) phenol; and S2, carrying out an elimination reaction on the 4-(2-hydroxypropyl-2-yl) phenol and beta zeolite in a solvent 2 to obtain the p-isopropenyl phenol. The preparation method provided by the invention only comprises two steps of reaction, is simple and efficient, is strong in atom economy, and is relatively high in yield and purity of the obtained target product; in addition, beta zeolite is used as a catalyst, is green and efficient, and can be recycled, so that the production cost is reduced, and the generation of solid wastes and acid-base wastewater is reduced; the two-step reaction and post-treatment conditions are mild, the operation is simple, and the method is suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of chemical synthesis, and particularly relates to a method for preparing p-isopropenyl phenol. BACKGROUND

[0002] As an important phenolic derivative, p-isopropenyl phenol has unique application value in the fields of organic synthesis, polymer materials and special chemicals due to the presence of phenolic hydroxyl and isopropenyl functional groups in its molecular structure.

[0003] The prior art mainly prepares p-isopropenyl phenol by a bisphenol A mother liquor method and a ketone-phosphorus reagent method. The bisphenol A mother liquor method uses the crystallization mother liquor in the production process of bisphenol A as a raw material, and generates p-isopropenyl phenol by heating and decomposition with an alkaline catalyst (such as sodium hydroxide, potassium carbonate, etc.). However, the bisphenol A mother liquor has complex components, contains a large amount of unreacted phenol, bisphenol A isomers (such as 2,4'-BPA) and by-products (such as chroman, indan, etc.), resulting in low selectivity (usually less than 70%) of the target product, and the product is prone to deterioration due to high activity. In addition, this method consumes a large amount of alkaline catalyst, and the catalyst is added in solid form, which is easy to scab and block the reactor under high temperature and reduced pressure conditions, affecting the stability of continuous production. The ketone-phosphorus reagent method introduces isopropenyl by Wittig reaction of a ketone compound (such as p-hydroxyacetophenone) with a phosphorus reagent (such as methyltriphenylphosphonium bromide). Although this method can achieve high selectivity, it has the defects of low yield, complicated reaction steps (requiring multi-step purification), serious pollution due to large amount of phosphorus reagent used, high cost of three wastes treatment, and increased operation difficulty due to decomposition of intermediates and products caused by light and heat.

[0004] The preparation process of p-isopropenyl phenol has long faced technical bottlenecks, and the existing methods generally have problems such as high cost, low yield and serious environmental pollution, which are difficult to meet the needs of industrial production. Therefore, it is of great significance to develop a preparation method with lower cost, higher yield, controllable product quality and more green environmental protection. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a method for preparing p-isopropenyl phenol, which has lower cost, higher yield, high product quality and is more green and environmentally friendly.

[0006] In order to achieve the above-mentioned purpose of the application, the present application provides the following technical solutions:

[0007] The present application provides a method for preparing p-isopropenyl phenol, comprising the following steps:

[0008] S1: carrying out a nucleophilic addition reaction of 4-hydroxyacetophenone and an alkyl magnesium halide in a tetrahydrofuran solution in solvent 1 to obtain 4-(2-hydroxyprop-2-yl)phenol;

[0009] S2: carrying out an elimination reaction of 4-(2-hydroxyprop-2-yl)phenol and a β zeolite in solvent 2 to obtain p-isopropenylphenol.

[0010] Preferably, in step S1, the alkyl magnesium halide is selected from methyl magnesium chloride and methyl magnesium bromide.

[0011] Preferably, in step S1, the solvent 1 is selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran and toluene.

[0012] Preferably, in step S1, the temperature of the nucleophilic addition reaction is 15-55℃.

[0013] Preferably, in step S1, the molar ratio of 4-hydroxyacetophenone to the alkyl magnesium halide is 1:1.5-3.

[0014] Preferably, in step S2, the solvent 2 is tetrahydrofuran, methyl tert-butyl ether or 2-methyltetrahydrofuran.

[0015] Preferably, in step S2, the temperature of the elimination reaction is 40-70℃.

[0016] Preferably, in step S2, the mass ratio of 4-(2-hydroxyprop-2-yl)phenol to the β zeolite is 1:0.05-0.5.

[0017] Preferably, in step S2, after the elimination reaction, further comprising post-treatment of the obtained elimination reaction liquid, the post-treatment comprising:

[0018] a) carrying out solid-liquid separation on the obtained elimination reaction liquid;

[0019] b) sequentially carrying out concentration, crystallization and filtration on the obtained filtrate;

[0020] c) drying the obtained crystals.

[0021] Preferably, in step S2, the crystallization comprises: mixing the concentrated filtrate with n-heptane, n-hexane or petroleum ether, and carrying out crystallization.

[0022] Technical effects

[0023] Compared with the prior art, the present application has the beneficial effects that the present application provides a method for preparing p-isopropenyl phenol. The intermediate 4-(2-hydroxypropan-2-yl)phenol is obtained by nucleophilic addition reaction of 4-hydroxyacetophenone and tetrahydrofuran solution of alkyl magnesium halide, and then p-isopropenyl phenol is obtained by elimination reaction with beta zeolite as catalyst and dehydrating agent. The preparation method has only two steps of reaction, is simple and efficient, has strong atom economy, and has relatively high yield and purity of the target product. In addition, the beta zeolite is used as the catalyst, which is green and efficient, and can be recycled and reused, thereby reducing the cost, reducing the generation of solid waste and acid and alkali wastewater, further reducing the post-treatment cost, and being suitable for industrial production. DETAILED DESCRIPTION

[0024] The present application will be described in detail below by way of examples, but it does not mean any unfavorable limitation of the present application. The present application has been described in detail herein, and the specific embodiment modes thereof are also disclosed. It will be obvious to those skilled in the art that various changes and improvements can be made to the specific embodiment modes of the present application without departing from the spirit and scope of the present application.

[0025] Unless otherwise specified, the present application has no special requirements for the source of the raw materials used, and commercially available goods known to those skilled in the art can be used.

[0026] The present application provides a method for preparing p-isopropenyl phenol, comprising the following steps:

[0027] S1: nucleophilic addition reaction of 4-hydroxyacetophenone and tetrahydrofuran solution of alkyl magnesium halide in solvent 1 to obtain 4-(2-hydroxypropan-2-yl)phenol;

[0028] S2: elimination reaction of 4-(2-hydroxypropan-2-yl)phenol and beta zeolite in solvent 2 to obtain p-isopropenyl phenol.

[0029] In the present application, the alkyl magnesium halide in step S1 is preferably selected from methyl magnesium chloride and methyl magnesium bromide, and more preferably is methyl magnesium chloride.

[0030] In the present application, the solvent 1 in step S1 is preferably one or more of tetrahydrofuran, 2-methyltetrahydrofuran and toluene.

[0031] In the present application, the temperature of the nucleophilic addition reaction in step S1 is preferably 15-55℃, and more preferably 15-45℃.

[0032] In the present application, the molar ratio of 4-hydroxyacetophenone to alkyl magnesium halide in step S1 is preferably 1:1.5-3, and more preferably 1:2-3.

[0033] After the nucleophilic addition reaction, the obtained nucleophilic addition reaction solution is preferably subjected to post-treatment in the present application; in the present application, the post-treatment preferably comprises the following steps:

[0034] After controlling the temperature of the nucleophilic addition reaction solution at 20-40℃, the acidic solution is added dropwise, the solution is allowed to stand and separate into layers, and the organic phase is collected; the organic phase is washed with the basic solution, allowed to stand and separate into layers, and the organic phase is collected again; the organic phase is subjected to concentration, beating, and filtration in sequence to obtain 4-(2-hydroxypropan-2-yl)phenol.

[0035] In the present application, the acidic solution is preferably a citric acid solution or an ammonium chloride solution, and more preferably a 10% mass fraction citric acid solution or a 20% mass fraction ammonium chloride solution; the unreacted alkyl magnesium halide Grignard reagent and the basic by-product are neutralized by adding the acidic solution during the post-treatment in the present application.

[0036] In the present application, the basic solution is preferably a sodium carbonate solution or a sodium bicarbonate solution, and more preferably a 5% mass fraction sodium bicarbonate solution; the added acidic solution is neutralized by adding the basic solution during the post-treatment in the present application.

[0037] In the present application, the solvent used for beating is preferably petroleum ether or n-heptane, and more preferably n-heptane.

[0038] In the present application, the beating operation temperature is preferably 10-30℃.

[0039] In the present application, the solvent 2 used in step S2 is preferably tetrahydrofuran, methyl tert-butyl ether, or 2-methyltetrahydrofuran.

[0040] In the present application, the temperature of the elimination reaction in step S2 is preferably 40-70℃, and more preferably 45-65℃.

[0041] In the present application, the mass ratio of 4-(2-hydroxypropan-2-yl)phenol to the β zeolite in step S2 is preferably 1:0.05-0.5, and more preferably 1:0.05-0.3.

[0042] After the elimination reaction in step S2, the obtained elimination reaction solution is preferably subjected to post-treatment in the present application; in the present application, the post-treatment preferably comprises the following steps:

[0043] a) subjecting the obtained elimination reaction solution to solid-liquid separation;

[0044] b) subjecting the obtained filtrate to concentration, crystallization, and filtration in sequence;

[0045] c) drying the obtained crystals.

[0046] The present application does not have special requirements for the solid-liquid separation mode, and any solid-liquid separation mode known to those skilled in the art can be used, and the specific mode is filtration.

[0047] The obtained elimination reaction liquid is subjected to solid-liquid separation, and beta zeolite is recovered, and filtrate is collected.

[0048] The obtained filtrate is added with phenolic polymerization inhibitor dibutyl hydroxytoluene, so as to prevent the product from polymerizing with p-isopropenyl phenol.

[0049] The concentration method is not particularly required in the present application, and a concentration method known to those skilled in the art can be used. In the present application, the concentration is preferably concentration to 20-30% of the original volume.

[0050] In the present application, the crystallization in step S2 is preferably crystallization of the concentrated filtrate mixed with n-heptane, n-hexane or petroleum ether, and is more preferably crystallization of the concentrated filtrate mixed with n-heptane.

[0051] In the present application, the crystallization temperature is preferably 0-10°C.

[0052] The mixing method is not particularly required in the present application, and a mixing method known to those skilled in the art can be used, such as stirring mixing.

[0053] The synthesis method of p-isopropenyl phenol in the present application will be described in detail below with reference to specific examples in the present application.

[0054] The present application provides the following synthesis route of p-isopropenyl phenol,

[0055]

[0056] Example 1

[0057] First step: synthesis of 4-(2-hydroxypropan-2-yl)phenol

[0058] A 4-hydroxyacetophenone (136.1g 1.00mol) solution in 950mL of tetrahydrofuran was placed in a reaction bottle, and the bottle was replaced with nitrogen, stirring was started, and the temperature of the reaction system was adjusted to 15-45°C; a methyl magnesium chloride (152.56g 2.04mol) solution in 700mL of tetrahydrofuran was added dropwise, and after the dropwise addition was completed, the temperature of the reaction system was controlled at 35-55°C, and the reaction was carried out for 12 hours. Sampling detection showed that the reaction reached the end point; a 10% citric acid solution was added dropwise while the temperature was controlled at 20-40°C, and after the dropwise addition was completed, the mixture was allowed to stand and separate into layers; the organic layer was washed with a 5% sodium bicarbonate solution, and the mixture was allowed to stand and separate into layers; the organic layer was concentrated under reduced pressure until no distillate was obtained, n-heptane was added at a temperature of 10-30°C, and then the mixture was filtered, and the filter cake was collected, thereby obtaining 136.8g of 4-(2-hydroxypropan-2-yl)phenol, with a yield of 90.0% and a purity of 98.2%.

[0059] Second step: synthesis of p-isopropenyl phenol

[0060] Into the reaction flask was added 4-(2-hydroxypropan-2-yl)phenol (136.8 g 0.89 mol), 700 mL of tetrahydrofuran and 13.68 g of beta zeolite, nitrogen was replaced to open the stirring and adjust the temperature of the reaction system to 55-65 °C; control the temperature of the reaction system at 55-65 °C for 4 hours, sample detection, reaction to the end; cooling to 20-30 °C, filter recovery beta zeolite, collect the filtrate; the filtrate was added dibutyl hydroxyl toluene, concentrated under reduced pressure to no fraction, the addition of n-heptane control temperature 0-10 °C crystallization 1 hour, filtration, filter cake was dried under reduced pressure to obtain 97.7 g of p-isopropenyl phenol, yield 81.0 %, purity 99.2 %.

[0061] Example 2

[0062] First step: synthesis of 4-(2-hydroxypropan-2-yl)phenol

[0063] Into the reaction flask was added 4-hydroxyacetophenone (136.1 g 1.00 mol), 950 mL of tetrahydrofuran solution, nitrogen was replaced to open the stirring and adjust the temperature of the reaction system to 15-45 °C; dropwise addition of methyl magnesium chloride (152.56 g 2.04 mol) tetrahydrofuran solution (700 mL), dropwise addition was completed, control the temperature of the reaction system at 35-55 °C, reaction 12 hours. Sample detection, reaction to the end; control the temperature 20-40 °C dropwise addition of 10 % mass fraction of citric acid solution, dropwise addition was completed, static stratification; organic layer was washed with 5 % mass fraction of sodium bicarbonate solution, static stratification; organic layer was concentrated under reduced pressure to no fraction, the addition of n-heptane to 10-30 °C temperature under the pulp, then filtration, collected filter cake, obtained 139.9 g of 4-(2-hydroxypropan-2-yl)phenol, yield 92.0 %, purity 98.6 %.

[0064] Second step: synthesis of p-isopropenyl phenol

[0065] Into the reaction flask was added 4-(2-hydroxypropan-2-yl)phenol (139.9 g 0.9 mol), 700 mL of tetrahydrofuran and 6.84 g of beta zeolite, nitrogen was replaced to open the stirring and adjust the temperature of the reaction system to 55-65 °C; control the temperature of the reaction system at 55-65 °C for 4 hours, sample detection, reaction to the end; cooling to 20-30 °C, filter recovery beta zeolite, collect the filtrate; the filtrate was added dibutyl hydroxyl toluene, concentrated under reduced pressure to no fraction, the addition of n-heptane control temperature 0-10 °C crystallization 1 hour, filtration, filter cake was dried under reduced pressure to obtain 99.9 g of p-isopropenyl phenol, yield 78.0 %, purity 99.1 %.

[0066] Example 3

[0067] Step 1: Synthesis of 4-(2-hydroxypropyl)phenol

[0068] Into a reaction flask was placed 4-hydroxyacetophenone (136.1 g 1.00 mol), 950 mL of tetrahydrofuran solution, and the system was stirred under nitrogen and the temperature was adjusted to 15-45 °C. A solution of methyl magnesium chloride (152.56 g 2.04 mol) in tetrahydrofuran (700 mL) was added dropwise. After the addition was completed, the temperature of the reaction system was controlled at 35-55 °C and the reaction was allowed to proceed for 12 hours. The reaction was sampled and detected to determine the end point. A 10% citric acid solution was added dropwise while the temperature was controlled at 20-40 °C. After the addition was completed, the system was allowed to stand and separate into layers. The organic layer was washed with a 5% sodium bicarbonate solution and allowed to stand and separate into layers. The organic layer was concentrated under reduced pressure until no distillate was obtained. N-heptane was added and the system was slurried at a temperature of 10-30 °C. The system was then filtered and the filter cake was collected to obtain 133.8 g of 4-(2-hydroxypropyl)phenol at a yield of 88.0% and a purity of 99.1%.

[0069] Step 2: Synthesis of p-isopropenylphenol

[0070] Into a reaction flask was placed 4-(2-hydroxypropyl)phenol (133.8 g 0.88 mol), 700 mL of tetrahydrofuran, and 26.8 g of beta zeolite. The system was stirred under nitrogen and the temperature was adjusted to 45-55 °C. The temperature of the reaction system was controlled at 45-55 °C and the reaction was allowed to proceed for 4 hours. The reaction was sampled and detected to determine the end point. The temperature was then lowered to 20-30 °C and the beta zeolite was recovered by filtration. The filtrate was collected. Dibutylhydroxytoluene was added to the filtrate and the system was concentrated under reduced pressure until no distillate was obtained. N-heptane was added and the system was crystallized at a temperature of 0-10 °C for 1 hour. The system was filtered and the filter cake was dried under reduced pressure to obtain 97.9 g of p-isopropenylphenol at a yield of 83.0% and a purity of 99.3%.

[0071] Example 4

[0072] Step 1: Synthesis of 4-(2-hydroxypropyl)phenol

[0073] Into the reaction bottle, 4-hydroxyacetophenone (136.1g 1.00mol), 950mL tetrahydrofuran solution, nitrogen replacement, open stirring and adjust the reaction system temperature to 15-45℃; drop methyl magnesium chloride (183.24g 2.45mol) tetrahydrofuran solution (700mL), drop to the end, control the reaction system temperature at 35-55℃, reaction 12 hours. Sampling detection, reaction to the end; control temperature 20-40℃ drop 20% mass fraction of ammonium chloride solution, drop to the end, static stratification; organic layer with 5% mass fraction of sodium bicarbonate solution washing, static stratification; organic layer reduced pressure concentration to no distillate, add n-heptane to 10-30℃ temperature under the pulp, then filter, collect the filter cake, to get 141.4g of 4-(2-hydroxypropan-2-yl) phenol, yield 93.0%, purity 98.8%.

[0074] Second step: synthesis of p-isopropenyl phenol

[0075] Into the reaction bottle, 4-hydroxyacetophenone (136.1g 1.00mol), 950mL tetrahydrofuran solution, nitrogen replacement, open stirring and adjust the reaction system temperature to 15-45℃; drop methyl magnesium chloride (183.24g 2.45mol) tetrahydrofuran solution (700mL), drop to the end, control the reaction system temperature at 35-55℃, reaction 12 hours. Sampling detection, reaction to the end; control temperature 20-40℃ drop 20% mass fraction of ammonium chloride solution, drop to the end, static stratification; organic layer with 5% mass fraction of sodium bicarbonate solution washing, static stratification; organic layer reduced pressure concentration to no distillate, add n-heptane to 10-30℃ temperature under the pulp, then filter, collect the filter cake, to get 141.4g of 4-(2-hydroxypropan-2-yl) phenol, yield 93.0%, purity 98.8%.

[0076] From the above examples, the present application is obtained by 4-hydroxyacetophenone and methyl magnesium chloride tetrahydrofuran solution for nucleophilic addition reaction to obtain intermediate 4-(2-hydroxypropan-2-yl) phenol, then with β zeolite as catalyst and dehydrating agent through elimination reaction to obtain p-isopropenyl phenol, the preparation method has only two steps of reaction, simple and efficient, strong atom economy, the yield and purity of the target product are relatively high. In addition, β zeolite is used as catalyst, which is green and efficient, and can be recycled and used, thereby reducing cost and reducing the generation of solid waste and acid and alkaline wastewater. The two-step reaction and post-treatment conditions are mild, simple operation, and suitable for industrialization.

[0077] Although the above examples make a detailed description of the present application, it is only a part of the embodiments of the present application but not all the embodiments, and other embodiments can be obtained under the premise of no creativity according to the present embodiments, which all belong to the protection scope of the present application.

Claims

1. A method for preparing p-isopropenylphenol, characterized in that: The following steps are involved: S1: 4-hydroxyacetophenone and a tetrahydrofuran solution of an alkyl magnesium halide are subjected to a nucleophilic addition reaction in solvent 1 to obtain 4-(2-hydroxypropan-2-yl)phenol; S2: performing an elimination reaction between the 4-(2-hydroxypropan-2-yl)phenol and beta zeolite in solvent 2 to obtain p-isopropenylphenol.

2. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S1, the alkyl magnesium halide is selected from methyl magnesium chloride and methyl magnesium bromide.

3. The method for preparing p-isopropenylphenol according to claim 2, wherein In step S1, the solvent 1 is selected from one or more of tetrahydrofuran, 2-methyltetrahydrofuran and toluene.

4. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S1, the temperature of the nucleophilic addition reaction is 15-55°C.

5. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S1, the molar ratio of 4-hydroxyacetophenone to alkyl magnesium halide is 1:1.5-3.

6. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S2, the solvent 2 is tetrahydrofuran, methyl tert-butyl ether or 2-methyltetrahydrofuran.

7. The method for preparing p-isopropenylphenol according to claim 6, wherein In step S2, the temperature of the elimination reaction is 40-70°C.

8. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S2, the mass ratio of the 4-(2-hydroxyprop-2-yl)phenol to the beta zeolite is 1:0.05-0.

5.

9. The method for preparing p-isopropenylphenol according to claim 1, wherein In step S2, after the elimination reaction, the obtained elimination reaction liquid is subjected to post-treatment, and the post-treatment includes: a) carrying out solid-liquid separation on the obtained elimination reaction liquid; b) the obtained filtrate is concentrated, crystallized and filtered in sequence; c) drying the obtained crystals.

10. The method for preparing p-isopropenylphenol according to claim 9, wherein The crystallization comprises: mixing the concentrated filtrate with n-heptane, n-hexane or petroleum ether to perform crystallization.

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