Preparation method of 2, 6-di-tert-butyl-4-phenyl-2, 5-cyclohexadienyl-1-ketone

Abstract

The invention discloses a preparation method of 2, 6-di-tert-butyl-4-phenyl-2, 5-cyclohexadienyl-1-one, which comprises the following steps of: adding a catalyst and a catalyst into a reaction kettle; relates to the field of organic synthesis. The 2, 6-di-tert-butyl-4-phenyl-2, 5-cyclohexadienyl-1-ketone is prepared by taking secondary amine as a catalyst, taking 2, 6-di-tert-butylphenol and benzaldehyde as raw materials and taking di-n-butylamine as a catalyst and adopting a one-pot boiling mode, the conversion rate of the main raw materials in the whole reaction stage reaches 98%, the product purity reaches 99.5%, and the yield of the 2, 6-di-tert-butyl-4-phenyl-2, 5-cyclohexadienyl-1-ketone is high. The preparation method has the advantages of high raw material utilization rate, high product yield, less waste and environmental protection. Secondly, the sulfonic acid modified zeolite is subjected to acid steam roasting treatment, so that groups of the sulfonic acid modified zeolite are uniformly distributed on the surface and in pores of the zeolite, and the thermal stability and the chemical stability of the modified zeolite are effectively improved; the liquid exchanged by the sulfonic acid modified zeolite is distilled and purified to recover the di-n-butylamine, so that the loss rate of the di-n-butylamine sulfate is further reduced, the recovery rate is up to 95-97.1%, and the purposes of feeding the next batch and recycling are achieved.

Description

Technical Field

[0001] The invention relates to the field of organic synthesis, and in particular to a method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone. Background Art

[0002] 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone is an orange-yellow crystal that is insoluble in water and has a melting point of 74-75°C. As a new type of polymerization inhibitor, 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone has excellent performance, and compared with other types of polymerization inhibitors, it has the characteristics of low toxicity and green environmental protection, and has broad application prospects.

[0003] The traditional Mannich reaction requires high temperature or high pressure conditions, which not only increases the complexity and cost of the operation, but also easily produces by-products under long-term high temperature and high pressure conditions. It may also affect the safety of the reaction and produce a large amount of volatile pollutants. Usually, the reaction requires further complex and tedious transformation or treatment to remove the by-products in order to meet the purity requirements of the final product, thus increasing the chemical steps and costs. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one, which has the advantages of high utilization rate of raw materials and auxiliary materials, good continuous productivity, low pollution, low cost, and high product yield, purity and content.

[0005] The above-mentioned object of the present invention is achieved through the following technical scheme: in the reaction stage, the one-pot feeding operation is simple and convenient, with good safety, and gas chromatography is used to monitor the reaction conversion.

[0006] Preferably, a method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone, the specific preparation method is as follows:

[0007] S1: Reaction stage: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde were added to the reactor in sequence, and the mixture was mechanically stirred at 50-80 r / min for 10 min, and then the stirring speed was increased to 150-200 r / min. While stirring, the temperature of the reaction system was raised to reflux and water separation for 20-24 h; after the water separation was completed, the pH of the reaction solution after cooling was adjusted with 20wt% dilute sulfuric acid, and di-n-butylamine was salted and entered the water phase, and the water phase and the organic phase were separated by a water separator, and the organic phase was distilled under reduced pressure conditions of 40-50 kPa and 30°C to obtain a crude product;

[0008] S2: Refining stage: The crude product obtained in the reaction stage is added with methanol at a ratio of 1 g crude product / 50 mL, and the temperature is raised to 40-45°C. After the crude product is completely dissolved, the solution is cooled to 5-10°C, and the solid is centrifuged at a speed of 10000 r / min for 20-25 min to obtain the solid, and then dried in a 25°C forced air oven for 30 min to obtain the final product;

[0009] S3: Recovery stage: Add sulfonic acid modified zeolite to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1g modified zeolite / 20-25mL aqueous phase, oscillate in a constant temperature water bath at 30°C for 2h at a speed of 150r / min, and then use a sand core funnel to separate the solid and liquid to obtain dilute sulfuric acid and sulfonic acid modified zeolite respectively; use a sand core funnel to rinse and filter the sulfonic acid modified zeolite, first rinse with 1000mL deionized water for 3-5 times, and then rinse with 1000-1 The mixture was eluted with 500 mL of anhydrous ethanol, the eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide, and then added into a distillation flask for distillation purification, heated at 60-70°C for 60 min, the temperature was gradually increased to 78°C, heated for 1 h to collect ethanol, and then the temperature was gradually increased to 159°C, refluxed for 2-3 h to recover di-n-butylamine; the collected dilute sulfuric acid was added into a distillation flask, evaporated at 105-120°C for 60-90 min, and sulfuric acid was recovered.

[0010] Preferably, the main raw material conversion rate in S1 can reach 98%.

[0011] Preferably, the molar ratio of 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde in S1 is 1:0.5:1.2.

[0012] Preferably, the reflux water separation reaction in S1 is heated to 90-100°C.

[0013] Preferably, the acid adjustment temperature of the reaction solution in S1 is controlled at 70-80°C.

[0014] Preferably, the amount of sulfuric acid in S1 is 0.51 equivalents of the amine.

[0015] Preferably, after the solvent is distilled off under reduced pressure in S1, a proper amount of purified water is added to the crude product in the kettle to evaporate it, and the benzaldehyde is collected and extracted to recover it, and then recycled to the next batch of feed.

[0016] Preferably, the crude product in S2 is added with an alcohol solvent to heat and dissolve, and then cooled and crystallized. The product has good properties, and the finished product obtained by drying has high purity and good color, and is not easy to agglomerate during long-term storage.

[0017] Preferably, the preparation method of the sulfonic acid modified zeolite in S3 is: placing the zeolite in a roasting furnace at 1-5 m 38-10 wt % sulfuric acid vapor is introduced at a volume flow rate of / h, and calcined at 280-300°C for 4-5h to obtain the sulfonic acid modified zeolite.

[0018] Preferably, the recovery rate of the amine in S3 can reach 95-97.1%, and the amine can be recycled and directly used for the next batch of feed.

[0019] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0020] The present invention adopts a one-pot cooking method, uses a secondary amine as a catalyst, and uses 2,6-di-tert-butylphenol and benzaldehyde as raw materials to prepare 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone, thereby achieving a high raw material utilization rate, a high product yield, less waste, and a green and environmentally friendly preparation process effect;

[0021] Firstly, the present invention uses 2,6-di-tert-butylphenol and benzaldehyde as raw materials, adds di-n-butylamine to carry out Mannich reaction, generates corresponding Mannich base, makes Mannich base in-situ deamination, combines Mannich reaction into one step by one-pot method, thereby greatly shortens reaction time, reduces loss of intermediates, effectively reduces reaction steps, and reduces process cost; after reducing pressure on organic phase to evaporate solvent, obtains crude 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone, heats and dissolves in alcohol solvent, cools and centrifuges to obtain refined finished product, and the conversion rate of main raw materials in the whole reaction stage reaches 98%;

[0022] Secondly, a sulfonic acid modified zeolite rich in sulfonic acid groups is prepared by subjecting the zeolite to an acidic steam calcination treatment. The acidic steam calcination treatment allows the acidic steam to fully infiltrate the zeolite pores, which is beneficial for the groups to be evenly distributed on the surface and inside the pores of the zeolite, thereby effectively improving the thermal stability and chemical stability of the modified zeolite. The pH value of the reaction system is adjusted by dilute sulfuric acid, and di-n-butylamine enters the water phase after salt formation. The liquid separated by the water separator uses the sulfonic acid modified zeolite to absorb and exchange the organic ammonium ions in the water phase. The solution is collected and concentrated to a certain extent, and the obtained dilute sulfuric acid is added back to the system for adjusting the pH value of the reaction system. At the same time, -SO3 The H group is conducive to the adsorption and diffusion of di-n-butylamine sulfate, thereby improving the efficiency of ion exchange; the organic ammonium ions above are eluted by an alcohol solvent, the eluate is collected and the pH value is adjusted to 12 with liquid alkali, and then distilled and purified to recover di-n-butylamine, thereby effectively reducing the loss rate of di-n-butylamine sulfate, so that the recovery rate is as high as 95-97.1%, thereby achieving the purpose of inputting into the next batch of materials and recycling; at the same time, after the organic phase is decompressed and the solvent is evaporated, the excess benzaldehyde in the solvent is evaporated cleanly by purified water, and the benzaldehyde is extracted and recovered by using an organic solvent, so as to be recycled and input into the next batch of materials for reaction. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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 ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] In order to more clearly illustrate the method provided by the present invention, the following examples are used to describe in detail. In the following examples and comparative examples, the purity of 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one and the recovery rate of di-n-butylamine are calculated as follows:

[0025] 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadien-1-one purity (%) = actual 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadien-1-one mass / theoretical 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadien-1-one mass × 100%

[0026] Recovery rate of di-n-butylamine (%) = mass of di-n-butylamine recovered / mass of di-n-butylamine added in the reaction × 100%

[0027] Example 1; S1: Reaction stage: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde were added to the reactor in a molar ratio of 1:0.5:1.2, and the mixture was mechanically stirred at 75 r / min for 10 min, and then the stirring speed was increased to 160 r / min. While stirring, the temperature of the reaction system was raised to 90°C and refluxed for 20 h; after the water separation was completed, the temperature was adjusted to 80°C with 20wt% dilute sulfuric acid, and the pH of the reaction solution was adjusted to 80°C. The amount of dilute sulfuric acid used was 0.51 equivalents of di-n-butylamine. The di-n-butylamine was salified and entered the aqueous phase. The aqueous phase and the organic phase were separated by a water separator, and the organic phase was distilled under reduced pressure conditions of 40 kPa and 30°C to obtain a crude product;

[0028] S2: Refining stage: The crude product obtained in the reaction stage is added with methanol at a ratio of 1 g crude product / 50 mL, and the temperature is raised to 40°C. After the crude product is completely dissolved, the solution is cooled to 10°C, and the solid is centrifuged at a speed of 10,000 r / min for 20 min to obtain the solid, and then dried in a 25°C forced air oven for 30 min to obtain the final product;

[0029] S3: Recovery stage: The preparation method of sulfonic acid modified zeolite is as follows: zeolite is placed in a roasting furnace at 1.5 m 38 wt % sulfuric acid vapor was introduced at a volume flow rate of / h, and calcined at 280°C for 4h to obtain sulfonic acid modified zeolite; sulfonic acid modified zeolite was added to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1 g modified zeolite / 25 mL aqueous phase, and oscillated for 2h in a constant temperature water bath at 30°C at a speed of 150r / min, and then solid-liquid separation was performed using a sand core funnel to obtain dilute sulfuric acid and sulfonic acid modified zeolite respectively; the sulfonic acid modified zeolite was rinsed and filtered using a sand core funnel, and first 100 The mixture was rinsed with 1000 mL of deionized water for 3 times, then eluted with 1200 mL of anhydrous ethanol, the eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide, and the liquid was added into a distillation flask for distillation purification. After heating at 60 ° C for 60 min, the temperature was gradually increased to 78 ° C, and the ethanol was collected after heating for 1 h. The temperature was gradually increased to 159 ° C, and refluxed for 2 h to recover di-n-butylamine. The collected dilute sulfuric acid was added into a distillation flask, evaporated at 105 ° C for 75 min, and the sulfuric acid was recovered.

[0030] Example 2; S1: Reaction stage: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde were added to the reactor in a molar ratio of 1:0.5:1.2, and the mixture was mechanically stirred at 70 r / min for 10 min, and then the stirring speed was increased to 175 r / min. While stirring, the temperature of the reaction system was raised to 95°C and refluxed for 24 h; after the water separation, the temperature was adjusted to 75°C with 20wt% dilute sulfuric acid to adjust the pH of the reaction solution, the amount of dilute sulfuric acid was 0.51 equivalents of di-n-butylamine, and the di-n-butylamine was salted and entered the aqueous phase, and the aqueous phase and the organic phase were separated by a water separator, and the organic phase was distilled under reduced pressure conditions of 50 kPa and 30°C to obtain a crude product;

[0031] S2: Refining stage: The crude product obtained in the reaction stage is added with methanol at a ratio of 1 g crude product / 50 mL, and the temperature is raised to 45°C. After the crude product is completely dissolved, the solution is cooled to 8°C, and the solid is centrifuged at a speed of 10,000 r / min for 25 min to obtain the solid, and then dried in a 25°C forced air oven for 30 min to obtain the final product;

[0032] S3: Recovery stage: The preparation method of sulfonic acid modified zeolite is as follows: zeolite is placed in a roasting furnace at 3m 310 wt% sulfuric acid vapor was introduced at a volume flow rate of / h, and calcined at 300°C for 5h to obtain sulfonic acid modified zeolite; sulfonic acid modified zeolite was added to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1g modified zeolite / 20mL aqueous phase, and oscillated for 2h in a constant temperature water bath at 30°C at a speed of 150r / min, and then solid-liquid separation was performed using a sand core funnel to obtain dilute sulfuric acid and sulfonic acid modified zeolite respectively; the sulfonic acid modified zeolite was rinsed and filtered with a sand core funnel, and first 10 The mixture was rinsed with 100 mL of deionized water for 5 times, and then eluted with 1500 mL of anhydrous ethanol. The eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide, and then the liquid was added to a distillation flask for distillation purification. After heating at 65 ° C for 60 min, the temperature was gradually increased to 78 ° C, and the ethanol was collected after heating for 1 h. The temperature was gradually increased to 159 ° C, and refluxed for 3 h to recover di-n-butylamine; the collected dilute sulfuric acid was added to a distillation flask, evaporated at 110 ° C for 70 min, and sulfuric acid was recovered.

[0033] Example 3; S1: Reaction stage: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde were added to the reactor in a molar ratio of 1:0.5:1.2, and the mixture was mechanically stirred at 80 r / min for 10 min, and then the stirring speed was increased to 200 r / min. While stirring, the temperature of the reaction system was raised to 100°C and refluxed for 22 h; after the water separation was completed, the temperature was adjusted to 70°C with 20wt% dilute sulfuric acid, and the pH of the reaction solution was adjusted. The amount of dilute sulfuric acid was 0.51 equivalents of di-n-butylamine. The di-n-butylamine was salified and entered the aqueous phase. The aqueous phase and the organic phase were separated by a water separator. The organic phase was distilled under reduced pressure conditions of 45 kPa and 30°C to obtain a crude product;

[0034] S2: Refining stage: The crude product obtained in the reaction stage is added with methanol at a ratio of 1 g crude product / 50 mL, and the temperature is raised to 40°C. After the crude product is completely dissolved, the solution is cooled to 5°C, and the solid is centrifuged at a speed of 10,000 r / min for 20 min to obtain the solid, and then dried in a 25°C forced air oven for 30 min to obtain the final product;

[0035] S3: Recovery stage: The preparation method of sulfonic acid modified zeolite is as follows: zeolite is placed in a roasting furnace at 5m 38 wt % sulfuric acid vapor was introduced at a volume flow rate of / h, and calcined at 290°C for 4h to obtain sulfonic acid modified zeolite; sulfonic acid modified zeolite was added to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1 g modified zeolite / 25 mL aqueous phase, and oscillated for 2h in a constant temperature water bath at 30°C at a speed of 150r / min, and then solid-liquid separation was performed using a sand core funnel to obtain dilute sulfuric acid and sulfonic acid modified zeolite respectively; the sulfonic acid modified zeolite was rinsed and filtered using a sand core funnel, first with 1000 mL of deionized water for 5 times, then eluted with 1000 mL of anhydrous ethanol, collected the eluate and adjusted the pH to 12 with 0.1 mol / L sodium hydroxide, then added the liquid into a distillation flask for distillation purification, heated at 65°C for 60 min, gradually raised the temperature to 78°C, heated for 1 h to collect ethanol, then gradually raised the temperature to 159°C, refluxed for 2.5 h to recover di-n-butylamine; added the collected dilute sulfuric acid into a distillation flask, evaporated at 120°C for 60 min, and recovered sulfuric acid.

[0036] Comparative Example 1; The difference between Comparative Example 1 and Example 2 is that the reaction stage is different, and the reaction stage is changed to: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde are added in the reactor in a molar ratio of 1:0.3:1.5, and the mixture is mechanically stirred at 70 r / min for 10 minutes, and then the stirring speed is increased to 175 r / min. While stirring, the temperature of the reaction system is raised to 95°C and refluxed for 24 hours; after the water separation is completed, the temperature is adjusted to 75°C with 20wt% dilute sulfuric acid, and the pH of the reaction solution is adjusted to 75°C. The amount of dilute sulfuric acid used is 0.51 equivalents of di-n-butylamine. Di-n-butylamine is salified and enters the aqueous phase. The aqueous phase and the organic phase are separated by a water separator, and the organic phase is distilled under reduced pressure conditions of 50 kPa and 30°C to obtain a crude product; the remaining steps are the same as Example 2.

[0037] Comparative Example 2; The difference between Comparative Example 2 and Example 2 is that the reaction stage is different, and the reaction stage is changed to: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde are added in sequence in a molar ratio of 1:0.5:1.2 in the reactor, and the mixture is mechanically stirred at 70 r / min for 10 minutes, and then the stirring speed is increased to 175 r / min. While stirring, the temperature of the reaction system is raised to 95°C and refluxed for 24 hours; after the water separation is completed, the temperature is adjusted to 70°C with 10wt% dilute sulfuric acid, and the pH of the reaction solution is adjusted to 70°C. The amount of dilute sulfuric acid used is 0.25 equivalents of di-n-butylamine. Di-n-butylamine is salified and enters the aqueous phase. The aqueous phase and the organic phase are separated by a water separator, and the organic phase is distilled under reduced pressure conditions of 50 kPa and 30°C to obtain a crude product; the remaining steps are the same as Example 2.

[0038] Comparative Example 3: The difference between Comparative Example 3 and Example 2 is that the recovery stage is different. The recovery stage is changed to: zeolite is added to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1g zeolite / 20mL aqueous phase, and oscillated for 2h in a constant temperature water bath at 30°C at a speed of 150r / min, and then solid-liquid separation is performed using a sand core funnel to obtain a liquid and zeolite respectively; the zeolite is rinsed and filtered while being rinsed with 1000mL deionized water 5 times, and then eluted with 1500mL anhydrous ethanol, the eluate is collected and the pH is adjusted to 12 with 0.1mol / L sodium hydroxide, and then the liquid is added to a distillation flask for distillation and purification, and the temperature is gradually increased to 78°C after heating at 65°C for 60min, and the ethanol is collected after heating for 1h, and then the temperature is gradually increased to 159°C, and the di-n-butylamine is recovered by reflux for 3h; the remaining steps are the same as Example 2.

[0039] Comparative Example 4; The difference between Comparative Example 4 and Example 2 is that the recovery stage is different. The recovery stage is changed to: the zeolite is added to 10wt% dilute sulfuric acid and soaked at room temperature for 5h to obtain a modified zeolite, and the modified zeolite is added to the aqueous phase separated by the water separator in the reaction stage according to the ratio of 1g modified zeolite / 20mL aqueous phase, and oscillated for 2h under a constant temperature water bath at 30°C, the speed is 150r / min, and then the solid-liquid separation is performed with a sand core funnel to obtain a liquid and a modified zeolite respectively; the modified zeolite is washed and filtered with a sand core funnel, and the first The mixture was rinsed with 1000 mL of deionized water for 5 times, and then eluted with 1500 mL of anhydrous ethanol. The eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide. The liquid was added to a distillation flask for distillation purification. After heating at 65° C. for 60 min, the temperature was gradually increased to 78° C., and the ethanol was collected after heating for 1 h. The temperature was gradually increased to 159° C., and refluxed for 3 h to recover di-n-butylamine. The collected liquid was added to a distillation flask, evaporated at 110° C. for 70 min, and sulfuric acid was recovered. The remaining steps were the same as those in Example 2.

[0040] Comparative Example 5; The difference between Comparative Example 5 and Example 2 is that the recovery stage is different, and the recovery stage is changed to: Amberlite IR-120 cation exchange resin is added to the aqueous phase separated by the water separator in the reaction stage according to the ratio of 1gAmberlite IR-120 cation exchange resin / 20mL aqueous phase, and oscillated for 2h in a constant temperature water bath at 30°C, with a speed of 150r / min, and then solid-liquid separation is performed with a sand core funnel to obtain a liquid and an Amberlite IR-120 cation exchange resin, respectively; Amberlite The IR-120 cation exchange resin was rinsed and filtered at the same time, first rinsed with 1000 mL of deionized water for 5 times, and then eluted with 1500 mL of anhydrous ethanol, the eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide, and the liquid was added to a distillation flask for distillation purification, heated at 65°C for 60 min, the temperature was gradually increased to 78°C, heated for 1 h to collect ethanol, and then the temperature was gradually increased to 159°C, refluxed for 3 h to recover di-n-butylamine; the collected liquid was added to a distillation flask, evaporated at 110°C for 70 min, and sulfuric acid was recovered; the remaining steps were the same as in Example 2.

[0041] Comparative Example 6; The difference between Comparative Example 6 and Example 2 is that the recovery stage is different, and the recovery stage is changed to: in the aqueous phase separated by the water separator in the reaction stage according to 1g ZSM-5 molecular sieves were added in a ratio of ZSM-5 molecular sieves / 20 mL of aqueous phase, and the mixture was oscillated in a constant temperature water bath at 30° C. for 2 h at a speed of 150 r / min. A sand core funnel was then used to perform solid-liquid separation to obtain a liquid and a ZSM-5 molecular sieve, respectively. The ZSM-5 molecular sieves were rinsed and filtered with a sand core funnel, first rinsed with 1000 mL of deionized water for 5 times, and then eluted with 1500 mL of anhydrous ethanol. The eluate was collected and the pH was adjusted to 12 with 0.1 mol / L of sodium hydroxide, and then the liquid was added to a distillation flask for distillation and purification. After heating at 65° C. for 60 min, the temperature was gradually increased to 78° C., and ethanol was collected after heating for 1 h. The temperature was gradually increased to 159° C., and the mixture was refluxed for 3 h to recover di-n-butylamine. The collected liquid was added to a distillation flask, evaporated at 110° C. for 70 min, and sulfuric acid was recovered. The remaining steps were the same as those in Example 2.

[0042] Effect example

[0043] Table 1 below shows the results of the purity of 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one and the recovery rate of di-n-butylamine in Examples 1 to 3 of the present invention and Comparative Examples 1 to 4.

[0044] Table 1

[0045]

[0046] From the comparison of the experimental data of the purity of 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone and the recovery rate of di-n-butylamine in the embodiment and the comparative example, it can be found that the present invention combines the Mannich reaction into a one-step process through a one-pot method, thereby greatly shortening the reaction time, reducing the loss of intermediates, effectively reducing the reaction steps, and reducing the process cost. The refined finished product is obtained by heating, dissolving, cooling, and centrifuging in an alcohol solvent, and the conversion rate of the main raw material in the whole reaction stage reaches 98%; the sulfonic acid modified zeolite treated by acid steam roasting has its groups evenly distributed on the surface of the zeolite and inside the pores, thereby effectively improving the thermal stability and chemical stability of the modified zeolite, and the liquid exchanged with the sulfonic acid modified zeolite is distilled and purified to recover di-n-butylamine, thereby effectively reducing the loss rate of di-n-butylamine sulfate, so that the recovery rate is as high as 95-97.1%, thereby achieving the purpose of feeding the next batch of materials and recycling; at the same time, the -SO3H group is conducive to the adsorption and diffusion of di-n-butylamine sulfate, thereby improving the efficiency of ion exchange.

[0047] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention, and any mark in the claims should not be regarded as limiting the claims involved.

Claims

1. A method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone, characterized in that: The specific preparation method is as follows: S1: Reaction stage: 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde were added to the reactor in sequence, and the mixture was mechanically stirred at 50-80 r / min for 10 min, and then the stirring speed was increased to 150-200 r / min. While stirring, the temperature of the reaction system was raised to reflux and water separation for 20-24 h; after the water separation was completed, the pH of the reaction solution after cooling was adjusted with 20wt% dilute sulfuric acid, and di-n-butylamine was salted and entered the water phase, and the water phase and the organic phase were separated by a water separator, and the organic phase was distilled under reduced pressure conditions of 40-50 kPa and 30°C to obtain a crude product; S2: Refining stage: The crude product obtained in the reaction stage is added with methanol at a ratio of 1 g crude product / 50 mL, and the temperature is raised to 40-45°C. After the crude product is completely dissolved, the solution is cooled to 5-10°C, and the solid is centrifuged at a speed of 10000 r / min for 20-25 min to obtain the solid, and then dried in a 25°C forced air oven for 30 min to obtain the final product; S3: Recovery stage: Add sulfonic acid modified zeolite to the aqueous phase separated by the water separator in the reaction stage at a ratio of 1g modified zeolite / 20-25mL aqueous phase, oscillate in a constant temperature water bath at 30°C for 2h at a speed of 150r / min, and then use a sand core funnel to separate the solid and liquid to obtain dilute sulfuric acid and sulfonic acid modified zeolite respectively; use a sand core funnel to rinse and filter the sulfonic acid modified zeolite, first rinse with 1000mL deionized water for 3-5 times, and then rinse with 1000-1 The mixture was eluted with 500 mL of anhydrous ethanol, the eluate was collected and the pH was adjusted to 12 with 0.1 mol / L sodium hydroxide, and then added into a distillation flask for distillation purification, heated at 60-70°C for 60 min, the temperature was gradually increased to 78°C, heated for 1 h to collect ethanol, and then the temperature was gradually increased to 159°C, refluxed for 2-3 h to recover di-n-butylamine; the collected dilute sulfuric acid was added into a distillation flask, evaporated at 105-120°C for 60-90 min, and sulfuric acid was recovered.

2. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one according to claim 1, characterized in that: The main raw material conversion rate in S1 can reach 98%.

3. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone according to claim 1, characterized in that: The molar ratio of 2,6-di-tert-butylphenol, di-n-butylamine and benzaldehyde in S1 is 1:0.5:1.

2.

4. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone according to claim 1, characterized in that: The temperature of the reflux water in S1 is 90-100°C.

5. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one according to claim 1, characterized in that: The temperature of the dilute sulfuric acid in S1 when adjusting the pH is controlled at 70-80°C.

6. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one according to claim 1, characterized in that: The amount of dilute sulfuric acid used in S1 is 0.51 equivalents of di-n-butylamine.

7. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one according to claim 1, characterized in that: After the solvent is distilled off under reduced pressure in S1, purified water is added to the crude product in the kettle to evaporate it, and the benzaldehyde is collected and extracted to recover it, and then recycled to the next batch of feed.

8. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-one according to claim 1, characterized in that: The crude product in S2 is added with an alcohol solvent and heated to dissolve, then cooled to crystallize. The product has good properties, and the finished product obtained by drying has high purity and good color, and is not easy to agglomerate during long-term storage.

9. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone according to claim 1, characterized in that: The preparation method of the sulfonic acid modified zeolite in S3 is as follows: placing the zeolite in a roasting furnace at 1-5 m 3 8-10 wt % sulfuric acid vapor is introduced at a volume flow rate of / h, and calcined at 280-300°C for 4-5h to obtain the sulfonic acid modified zeolite.

10. The method for preparing 2,6-di-tert-butyl-4-phenyl-2,5-cyclohexadienyl-1-ketone according to claim 1, characterized in that: The recovery rate of amine in S3 can reach 95-97.1%, and it can be recycled and directly used for the next batch of feeding.

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