Synthetic method of p-tert-butylcatechol
By using a composite catalyst, the combination of multi-stage pore β zeolite and carboxymethyl chitosan is solved in the prior art, the cost, low yield and environmental pollution of synthesis of tert-butyl catechol is high, and an efficient and environmentally friendly synthesis process is achieved.
Patent Information
- Application Number
- CN202411790579.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-06
- Publication Date
- 2025-03-14
AI Technical Summary
The prior art has problems such as high production costs, low product yield, relatively low quality indicators and serious environmental pollution when synthesizing tert-butyl catechol.
Using a composite catalyst, a multi-stage porous β zeolite was prepared by treating the β zeolite with sodium hydroxide and ammonium chloride, and co-precipitated with carboxymethyl chitosan and oxides, and a composite catalyst with high catalytic activity and high life was prepared. The catalyst reacts with catechol and isobutene in an environment of 110 to 130°C, and catalytic efficiency is improved through multi-stage pore structure and hydroxylation reaction.
The synthesis of tert-butylcatechol with high catalytic activity and high yield has been achieved, the product quality has been improved, and the catalyst can be recycled, reducing production costs and environmental pollution.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of industrial catalysis, and particularly relates to a method for synthesizing p-tert-butylcatechol. Background Art
[0002] 4-tert-Butylcatechol is an important organic fine chemical product with a wide range of applications in the chemical industry. As a polymerization inhibitor, it can be used in monomers such as styrene, butadiene, chloroprene and isoprene, as well as vinyl chloride, vinyl pyridine, α-olefins, nonene, cyclopentadiene, acrylic acid, methacrylic acid and similar compounds, chlorinated olefins and polyurethanes.
[0003] In recent years, with the development of my country's petrochemical industry, especially the successive start-up of styrene production facilities in some oil companies, the domestic demand for tert-butylcatechol has also greatly increased. The current synthesis routes mainly include: (1) using catechol as the starting material, and undergoing an acid-catalyzed ring tert-butylation reaction with isobutylene; (2) using catechol as the starting material, and undergoing an acid-catalyzed ring tert-butylation reaction with tert-butyl alcohol; (3) using tert-butylphenol as the starting material, and undergoing hydrogen peroxide oxidation. (4) using tert-butylbenzene as the starting material, and undergoing chlorination and hydrolysis. The first method usually uses liquid strong acids such as sulfuric acid, phosphoric acid or sulfonic acid as catalysts. These strong acids are very corrosive to equipment, and a large amount of phenol-containing wastewater is generated, which not only wastes raw materials but also pollutes the environment. The raw material tert-butyl alcohol of the second method is relatively expensive, the yield of p-tert-butylcatechol of the third method is relatively low, the cost is relatively high, and the economic benefits are low, while the fourth method pollutes the environment during the production process. As the requirements for the environment become increasingly stringent, this method is generally not adopted.
[0004] At present, the mainstream process for synthesizing p-tert-butylcatechol is the catalytic synthesis of catechol phosphoric acid method and sulfuric acid method. These two catalytic synthesis methods are to add isobutylene in the presence of phosphoric acid or sulfuric acid and a catalyst to achieve synthesis, and then obtain the finished product through layering, neutralization, washing and vacuum distillation. These existing methods have the problems of high production costs, low product yields and relatively low quality indicators. Unless further treatment is carried out and the amount of acid or salt discharged is large, it will cause serious environmental pollution.
[0005] Therefore, providing a method for synthesizing p-tert-butylcatechol with high catalytic activity and long life is an urgent problem to be solved in the art. Summary of the invention
[0006] The purpose of the present invention is to overcome the problems existing in the above process route and provide a method for synthesizing p-tert-butylcatechol with high catalytic activity and long life.
[0007] To achieve the above object, the technical solution of the present invention includes the following contents:
[0008] One of the purposes of the present invention is to provide a synthesis of p-tert-butylcatechol, comprising the following steps:
[0009] The catechol, the composite catalyst and the mixed solvent A are mixed and stirred for 20 to 40 minutes, an inert gas is introduced to drive out the air and then isobutylene is introduced, and the mixture is reacted in an environment of 110 to 130° C. for 4 to 6 hours, and the reaction liquid and the composite catalyst are separated by filtration. The reaction liquid is purified to obtain the p-tert-butylcatechol.
[0010] Furthermore, the preparation of the composite catalyst comprises the following steps:
[0011] The beta zeolite is calcined at 450-500°C for 2-3 hours, then added to a sodium hydroxide solution, and stirred at 75-85°C for 30-60 minutes to obtain an intermediate product A, and the intermediate product A is dispersed in an ammonium chloride solution and subjected to an exchange reaction at 75-85°C for 2-3 hours. After the reaction is completed, a hierarchical pore beta zeolite is obtained;
[0012] Disperse carboxymethyl chitosan in mixed solvent B, add 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and 4-dimethylaminopyridine, stir and activate the reaction at 23-25°C for 0.5-1.5h, add hierarchical pore β zeolite in an inert gas protection environment after the reaction, stir and react for 20-24h to obtain hierarchical pore β zeolite wrapped with carboxymethyl chitosan;
[0013] Cerium chloride heptahydrate, ammonium metatungstate hydrate and hierarchical pore beta zeolite wrapped with carboxymethyl chitosan are dispersed in deionized water, the pH is adjusted to 10-12, the temperature is raised to 70-90° C. and stirred for reaction for 10-12 hours, and after the reaction is completed, the composite catalyst is obtained by filtering, washing, drying and roasting.
[0014] Furthermore, the weight ratio of the beta zeolite to the sodium hydroxide solution is 1-1.5:15-20.
[0015] Furthermore, the molar concentration of the sodium hydroxide solution is 0.2M.
[0016] Furthermore, the weight ratio of the intermediate product A to the ammonium chloride solution is 1-1.5:20-30.
[0017] Furthermore, the molar concentration of the ammonium chloride solution is 1M.
[0018] Furthermore, the mixed solvent B is prepared from deionized water and dimethyl sulfoxide in a weight ratio of 1:1.
[0019] Furthermore, the weight ratio of the carboxymethyl chitosan to the hierarchical pore beta zeolite is 2.5-5:1-1.5.
[0020] Furthermore, the weight ratio of the carboxymethyl chitosan, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and 4-dimethylaminopyridine is 1:0.29-0.43:0.23-0.34.
[0021] Furthermore, the weight ratio of the cerium chloride heptahydrate, ammonium metatungstate hydrate and the hierarchical pore beta zeolite wrapped with carboxymethyl chitosan is 1:2-5:8.5-9.
[0022] Furthermore, the molar ratio of catechol to isobutylene is 1:1 to 1.2.
[0023] Furthermore, the usage of the composite catalyst is 1% to 1.5% of the weight of catechol.
[0024] Furthermore, the mixed solvent A is prepared from toluene and dimethyl sulfoxide in a weight ratio of 9:1.
[0025] Furthermore, the inert gas is argon or nitrogen.
[0026] The second object of the present invention is to provide p-tert-butylcatechol synthesized by a method for synthesizing p-tert-butylcatechol.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] (1) Hierarchical pore β-zeolite is obtained by treating β-zeolite with sodium hydroxide solution and ammonium chloride solution, which increases the specific surface area and pore volume of β-zeolite. Hierarchical pore β-zeolite coated with carboxymethyl chitosan is prepared by esterification of silanol groups on the surface of hierarchical pore β-zeolite with carboxyl groups in carboxymethyl chitosan, which can protect the hierarchical pore β-zeolite from interference by the alkaline environment in subsequent reactions. Subsequently, cerium dioxide and tungsten trioxide are introduced by coprecipitation to prepare a composite catalyst. The prepared composite catalyst has high catalytic activity and reusability.
[0029] (2) During the use of the composite catalyst, the quaternary ammonium salt chitosan swells to form a fluffy network structure, gradually exposing the acid sites of the hierarchical pore β zeolite; in addition, while tungsten trioxide enhances the surface acidity of cerium dioxide, there is a synergistic effect between cerium and tungsten, which further improves the acid catalytic activity of the composite catalyst.
[0030] (3) The composite catalyst used in the present invention is easy to separate, has high activity and high selectivity, has few impurities, and has a high product yield; and the composite catalyst can be recycled for multiple times, and after a simple treatment after the catalytic activity decreases, it can still maintain a high catalytic activity. DETAILED DESCRIPTION
[0031] The technical solution of the present invention will be clearly and completely described below through the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.
[0032] Unless otherwise specified, the raw materials and reagents used in the present invention are commercially available or can be prepared by known methods.
[0033] Preparation Example 1:
[0034] The preparation of mixed solvent A comprises the following steps:
[0035] 900 parts by weight of toluene and 100 parts by weight of dimethyl sulfoxide were stirred at 35° C. for 10 minutes to prepare a mixed solvent A.
[0036] Preparation Example 2:
[0037] The preparation of mixed solvent B comprises the following steps:
[0038] 50 parts by weight of deionized water and 50 parts by weight of dimethyl sulfoxide were stirred at 25° C. for 3 minutes to prepare a mixed solvent B.
[0039] Preparation Example 3:
[0040] The preparation of the composite catalyst comprises the following steps:
[0041] 1.5 parts by weight of β zeolite was calcined at 500° C. for 2 h, then added to 20 parts by weight of 0.2 M sodium hydroxide solution, and stirred at 75° C. for 30 min to obtain an intermediate product A. 1 part by weight of the intermediate product A was dispersed in 30 parts by weight of 1 M ammonium chloride solution, and two ion exchange reactions were carried out at 85° C., each reaction lasting 1.5 h. After the reaction, a hierarchical pore β zeolite was obtained. 5 parts by weight of carboxymethyl chitosan was dispersed in 50 parts by weight of the mixed solvent B obtained in Preparation Example 2, and then 2.15 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.7 parts by weight of 4-dimethylaminopropylcarbodiimide were added. Methylaminopyridine, stirring and reacting at 25°C for 1h, after the reaction is completed, 1.5 parts by weight of multi-level porous β zeolite is added in a nitrogen protection environment, and the stirring reaction is carried out for 22h to obtain the multi-level porous β zeolite wrapped by carboxymethyl chitosan; 1 part by weight of cerium chloride heptahydrate, 5 parts by weight of ammonium metatungstate hydrate and 8.5 parts by weight of multi-level porous β zeolite wrapped by carboxymethyl chitosan are dispersed in 50 parts by weight of deionized water, after adjusting the pH to 10, the temperature is raised to 90°C, and the stirring reaction is carried out for 12h. After the reaction is completed, the mixture is filtered and washed, dried in an environment of 110°C for 12h, and then calcined in an environment of 500°C for 2h, and then ground and screened with a 60-mesh screen to obtain a composite catalyst.
[0042] Preparation Example 4:
[0043] The preparation of the composite catalyst includes the following processes:
[0044] 1.3 parts by weight of β-zeolite was calcined at 450° C. for 2.5 h, added to 18 parts by weight of 0.2 M sodium hydroxide solution, and stirred at 80° C. for 60 min to obtain an intermediate product A. 1.3 parts by weight of the intermediate product A was dispersed in 25 parts by weight of 1 M ammonium chloride solution and subjected to two ion exchange reactions at 75° C., each reaction lasting 1 h. After the reaction, a hierarchical pore β-zeolite was obtained. 4 parts by weight of carboxymethyl chitosan was dispersed in 50 parts by weight of the mixed solvent B obtained in Preparation Example 2, and 1.16 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.92 parts by weight of 4- dimethylaminopyridine, stirring and reacting at 23°C for 0.5h, after the reaction is completed, 1.2 parts by weight of multi-level porous β zeolite is added in an argon protection environment, and the reaction is stirred for 20h to obtain carboxymethyl chitosan-coated multi-level porous β zeolite; 1 part by weight of cerium chloride heptahydrate, 4 parts by weight of ammonium metatungstate hydrate and 8.7 parts by weight of carboxymethyl chitosan-coated multi-level porous β zeolite are dispersed in 50 parts by weight of deionized water, the pH is adjusted to 11, the temperature is raised to 80°C, and the reaction is stirred for 11h. After the reaction is completed, it is filtered, washed, dried at 105°C for 11h, and then calcined at 460°C for 2.5, ground and screened with a 50-mesh sieve to obtain a composite catalyst.
[0045] Preparation Example 5:
[0046] The preparation of the composite catalyst includes the following processes:
[0047] 1.1 parts by weight of β-zeolite was calcined at 460° C. for 2 h, then added to 16 parts by weight of 0.2 M sodium hydroxide solution, and stirred at 80° C. for 50 min to obtain an intermediate product A. 1.2 parts by weight of the intermediate product A was dispersed in 25 parts by weight of 1 M ammonium chloride solution, and two ion exchange reactions were carried out at 80° C., each reaction lasting 1.2 h. After the reaction, a hierarchical pore β-zeolite was obtained. 3 parts by weight of carboxymethyl chitosan was dispersed in 50 parts by weight of the mixed solvent B obtained in Preparation Example 2, and then 1.05 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.9 parts by weight of 4- dimethylaminopyridine, stirring and reacting at 24°C for 1.5 hours, after the reaction is completed, add 1.3 parts by weight of multi-level porous β zeolite in a nitrogen protection environment, and stir and react for 24 hours to obtain multi-level porous β zeolite wrapped with carboxymethyl chitosan; disperse 1 part by weight of cerium chloride heptahydrate, 3 parts by weight of ammonium metatungstate hydrate and 8.6 parts by weight of multi-level porous β zeolite wrapped with carboxymethyl chitosan in 50 parts by weight of deionized water, adjust the pH to 11, heat to 75°C, stir and react for 11 hours, filter and wash after the reaction, dry in a 105°C environment for 11 hours, and then roast in a 450°C environment for 3 hours, grind and sieve with a 50-mesh screen to obtain a composite catalyst.
[0048] Preparation Example 6:
[0049] The preparation of the composite catalyst includes the following processes:
[0050] 1 part by weight of β-zeolite was calcined at 450° C. for 3 h, then added to 15 parts by weight of 0.2 M sodium hydroxide solution, and stirred at 85° C. for 40 min to obtain an intermediate product A. 1.5 parts by weight of the intermediate product A was dispersed in 20 parts by weight of 1 M ammonium chloride solution, and two ion exchange reactions were carried out at 75° C., each reaction lasting 1.5 h. After the reaction, a hierarchical pore β-zeolite was obtained. 2.5 parts by weight of carboxymethyl chitosan was dispersed in 50 parts by weight of the mixed solvent B obtained in Preparation Example 2, and 0.95 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 0.7 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added. 1 part of 4-dimethylaminopyridine, stirred and reacted at 25°C for 1h, after the reaction was completed, 1 part of multi-level porous β zeolite was added in an argon protection environment, and stirred and reacted for 20h to obtain carboxymethyl chitosan-coated multi-level porous β zeolite; 1 part of cerium chloride heptahydrate, 2 parts of ammonium metatungstate hydrate and 9 parts of multi-level porous β zeolite coated with carboxymethyl chitosan were dispersed in 50 parts of deionized water, the pH was adjusted to 12, the temperature was raised to 90°C, stirred and reacted for 10h, after the reaction was completed, the mixture was filtered and washed, dried at 100°C for 10h, and then calcined at 500°C for 2h, ground and screened with a 40-mesh screen to obtain a composite catalyst.
[0051] Preparation Example 7:
[0052] The preparation of the composite catalyst includes the following processes:
[0053] 1.5 parts by weight of β-zeolite was calcined at 500°C for 5h, added to 20 parts by weight of 0.2M sodium hydroxide solution, and stirred at 75°C for 30min to obtain intermediate product A; 1 part by weight of intermediate product A was dispersed in 30 parts by weight of 1M ammonium chloride solution and subjected to two ion exchange reactions at 85°C, each reaction lasting 1.5h. After the reaction, hierarchical pore β-zeolite was obtained; 1 part by weight of cerium chloride heptahydrate, 5 parts by weight of ammonium metatungstate hydrate and 8.5 parts by weight of hierarchical pore β-zeolite were dispersed in 50 parts by weight of deionized water, the pH was adjusted to 10, the temperature was raised to 90°C, the reaction was stirred for 12h, after the reaction was completed, the mixture was filtered and washed, dried at 110°C for 12h, calcined at 500°C for 2h, ground and sieved with a 60-mesh screen to obtain a composite catalyst.
[0054] Preparation Example 8:
[0055] The preparation of the composite catalyst comprises the following steps:
[0056] 1.5 parts by weight of β zeolite was calcined at 500° C. for 2 h, then added to 20 parts by weight of 0.2 M sodium hydroxide solution, and stirred at 75° C. for 30 min to obtain an intermediate product A. 1 part by weight of the intermediate product A was dispersed in 30 parts by weight of 1 M ammonium chloride solution, and two ion exchange reactions were carried out at 85° C., each reaction lasting 1.5 h. After the reaction, a hierarchical pore β zeolite was obtained. 5 parts by weight of carboxymethyl chitosan was dispersed in 50 parts by weight of the mixed solvent B obtained in Preparation Example 2, and then 2.15 parts by weight of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride and 1.7 1.5 parts by weight of 4-dimethylaminopyridine were added in a nitrogen atmosphere for stirring and reacting for 1 hour. After the reaction was completed, 1.5 parts by weight of multi-level porous β-zeolite were added and stirred for reaction for 22 hours to obtain carboxymethyl chitosan-coated multi-level porous β-zeolite. 1 part by weight of cerium chloride heptahydrate and 8.5 parts by weight of multi-level porous β-zeolite coated with carboxymethyl chitosan were dispersed in 50 parts by weight of deionized water, the pH value was adjusted to 10, the temperature was raised to 90°C, the reaction was stirred for 12 hours, after the reaction was completed, the catalyst was filtered and washed, dried at 110°C for 12 hours, calcined at 500°C for 2 hours, ground and sieved with a 60-mesh screen to obtain a composite catalyst.
[0057] Embodiment 1:
[0058] A synthesis of p-tert-butylcatechol comprises the following steps:
[0059] 170 parts by weight of catechol, 2.55 parts by weight of the composite catalyst prepared in Preparation Example 3 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 30 minutes, nitrogen was introduced to drive out the air, and then 102 parts by weight of isobutylene were introduced, and the mixture was reacted at 110°C for 6 hours. After the reaction was completed, the mixture was cooled to 23°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 5, and the mixture was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0060] Embodiment 2:
[0061] A synthesis of p-tert-butylcatechol comprises the following steps:
[0062] 160 parts by weight of catechol, 1.6 parts by weight of the composite catalyst prepared in Preparation Example 4 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 30 minutes, argon gas was introduced to drive out the air, and then 88 parts by weight of isobutylene were introduced, and the reaction was carried out at 100°C for 5 hours. After the reaction was completed, the mixture was cooled to 24°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 5, and the reaction solution was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0063] Embodiment 3:
[0064] A synthesis of p-tert-butylcatechol comprises the following steps:
[0065] 140 parts by weight of catechol, 1.68 parts by weight of the composite catalyst prepared in Preparation Example 5 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 40 minutes, argon gas was introduced to drive out the air, and then 84 parts by weight of isobutylene were introduced, and the mixture was reacted at 90°C for 6 hours. After the reaction was completed, the mixture was cooled to 25°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 5.5, and the mixture was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0066] Embodiment 4:
[0067] A synthesis of p-tert-butylcatechol comprises the following steps:
[0068] 130 parts by weight of catechol, 1.56 parts by weight of the composite catalyst prepared in Preparation Example 6 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 20 minutes, nitrogen was introduced to drive out the air, and then 75.4 parts by weight of isobutylene were introduced, and the reaction was carried out at 100°C for 4 hours. After the reaction was completed, the mixture was cooled to 25°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 6, and the reaction solution was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0069] Comparative Example 1:
[0070] A synthesis of p-tert-butylcatechol comprises the following steps:
[0071] 170 parts by weight of catechol, 2.55 parts by weight of the composite catalyst prepared in Preparation Example 7 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 30 minutes, nitrogen was introduced to drive out the air, and then 102 parts by weight of isobutylene were introduced, and the mixture was reacted at 110°C for 6 hours. After the reaction was completed, the mixture was cooled to 23°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 5, and the mixture was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0072] Comparative Example 2:
[0073] A synthesis of p-tert-butylcatechol comprises the following steps:
[0074] 170 parts by weight of catechol, 2.55 parts by weight of the composite catalyst prepared in Preparation Example 8 and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 30 minutes, nitrogen was introduced to drive out the air, and then 102 parts by weight of isobutylene were introduced, and the reaction was carried out at 110°C for 6 hours. After the reaction was completed, the mixture was cooled to 23°C, and the reaction solution and the composite catalyst were separated by filtration. The pH of the reaction solution was adjusted to 5, and the reaction solution was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times and then the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by atmospheric distillation, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0075] Comparative Example 3:
[0076] A synthesis of p-tert-butylcatechol comprises the following steps:
[0077] 170 parts by weight of catechol, 2.55 parts by weight of β zeolite and 1000 parts by weight of the mixed solvent A prepared in Preparation Example 1 were mixed and stirred for 30 minutes, nitrogen was introduced to drive out the air, and then 102 parts by weight of isobutylene were introduced, and the reaction was carried out at 110° C. for 6 hours. After the reaction was completed, the reaction mixture was cooled to 23° C. and filtered to obtain a reaction solution and a composite catalyst. The pH of the reaction solution was adjusted to 5, and the reaction solution was allowed to stand for stratification. The aqueous layer was extracted with ether for multiple times, and the organic phases were combined. The organic phases were washed, dried, and filtered, and the mixed solvent A was recovered by distillation under normal pressure, and then reduced pressure distillation was performed to obtain p-tert-butylcatechol.
[0078] Performance Test:
[0079] (1) Detection of catechol conversion rate and p-tert-butylcatechol yield:
[0080] Gas chromatography detection conditions for p-tert-butylcatechol: chromatographic column SPB-1; injection port temperature 260°C, split ratio 20:1; programmed temperature, initial temperature 160°C, maintained for 2 min, then increased to 270°C at a heating rate of 15°C / min, maintained at 270°C for 3 min; detector temperature 290°C, the detection results are shown in Table 1.
[0081] Table 1. Detection of conversion rate of catechol and yield of p-tert-butyl catechol
[0082]
[0083] As can be seen from Table 1, the conversion rate of catechol can reach more than 75% and the yield of the product p-tert-butylcatechol can reach more than 93% when the composite catalyst is used to synthesize p-tert-butylcatechol in Examples 1 to 4 of the present invention. However, the conversion rate of catechol and the yield of p-tert-butylcatechol synthesized by the synthesis method of Comparative Examples 1 to 3 are much lower than those of the synthesis method of Examples 1 to 4 of the present invention.
[0084] (2) Recyclability test of composite catalyst:
[0085] The composite catalysts obtained by filtration and separation in Examples 1 to 4 and Comparative Examples 1 to 3 were washed with deionized water and dried at 90° C. for 6 h, and then used again to synthesize p-tert-butylcatechol for repeatability testing. The test results are shown in Table 2.
[0086] Table 2. Recyclability of the composite catalyst in the synthesis of tert-butyl catechol (catechol conversion rate (%))
[0087]
[0088] As shown in Table 2, in the repeatability test of the composite catalyst, compared with Comparative Examples 1 to 3, the conversion rate of catechol of the composite catalyst used in Examples 1 to 4 has been maintained at more than 73%, and the composite catalyst still maintains a high catalytic activity when used for the fourth time.
[0089] The above-described embodiments provide a detailed description of the technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected.
Claims
1. A method for synthesizing tert-butylcatechol, characterized in that: The synthesis comprises the following steps: The catechol, the composite catalyst and the mixed solvent A are mixed and stirred for 20 to 40 minutes, an inert gas is introduced to drive out the air and then isobutylene is introduced, and the mixture is reacted in an environment of 90 to 110° C. for 4 to 6 hours, and the reaction liquid and the composite catalyst are separated by filtration. The reaction liquid is purified to obtain the p-tert-butylcatechol.
2. A method for synthesizing p-tert-butylcatechol as claimed in claim 1, characterized in that: The preparation of the composite catalyst comprises the following steps: The beta zeolite is calcined at 450-500°C for 2-3 hours, then added to a sodium hydroxide solution, and stirred at 75-85°C for 30-60 minutes to obtain an intermediate product A, and the intermediate product A is dispersed in an ammonium chloride solution and subjected to an exchange reaction at 75-85°C for 2-3 hours. After the reaction is completed, a hierarchical pore beta zeolite is obtained; Dispersing carboxymethyl chitosan in mixed solvent B, adding 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and 4-dimethylaminopyridine, stirring and reacting at 23-25° C. for 0.5-1.5 h, adding hierarchical pore β zeolite in an inert gas protection environment after the reaction, stirring and reacting for 20-24 h to obtain hierarchical pore β zeolite wrapped with carboxymethyl chitosan; Cerium chloride heptahydrate, ammonium metatungstate hydrate and hierarchical pore beta zeolite wrapped with carboxymethyl chitosan are dispersed in deionized water, the pH is adjusted to 10-12, the temperature is raised to 70-90° C. and stirred for reaction for 10-12 hours, and after the reaction is completed, the composite catalyst is obtained by filtering, washing, drying and roasting.
3. A method for synthesizing p-tert-butylcatechol as claimed in claim 2, characterized in that: The weight ratio of the beta zeolite to the sodium hydroxide solution is 1-1.5:15-20.
4. A method for synthesizing p-tert-butylcatechol as claimed in claim 2, characterized in that: The weight ratio of the carboxymethyl chitosan to the hierarchical pore beta zeolite is 2.5-5:1-1.
5.
5. A method for synthesizing p-tert-butylcatechol as claimed in claim 2, characterized in that: The weight ratio of the carboxymethyl chitosan, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and 4-dimethylaminopyridine is 1:0.29-0.43:0.23-0.
34.
6. A method for synthesizing p-tert-butylcatechol as claimed in claim 2, characterized in that: The weight ratio of the cerium chloride heptahydrate, the ammonium metatungstate hydrate and the hierarchical pore beta zeolite wrapped with carboxymethyl chitosan is 1:2-5:8.5-9.
7. A method for synthesizing p-tert-butylcatechol as claimed in claim 1, characterized in that: The molar ratio of catechol to isobutylene is 1:1 to 1.
2.
8. A method for synthesizing p-tert-butylcatechol as claimed in claim 1, characterized in that: The usage of the composite catalyst is 1% to 1.5% of the weight of catechol.
9. A method for synthesizing p-tert-butylcatechol as claimed in claim 1, characterized in that The mixed solvent A is prepared by mixing toluene and dimethyl sulfoxide in a weight ratio of 9:
1.
10. p-tert-butylcatechol synthesized by the method for synthesizing p-tert-butylcatechol according to any one of claims 1 to 9.