A method and device for synthesizing 4,4'-dihydroxybiphenyl

Abstract

The present invention relates to the technical field of preparation of 4,4'-dihydroxybiphenyl, and more particularly to a method and device for synthesizing 4,4'-dihydroxybiphenyl. The synthesis method is: a high boiling point solvent is obtained after a solvent and a boiling point auxiliary agent are mixed uniformly; 3,3',5,5'-tetra-tert-butylbiphenol and a high boiling point solvent are mixed to obtain a first solution; Lewis acid and a reducing auxiliary agent are mixed with a high boiling point solvent to obtain a second solution; the first solution is placed in a synthesis device, and the second solution is dripped into the first solution under nitrogen protection, and the reaction is continued after the dropwise addition until no isobutylene gas is produced to obtain a reaction completion liquid; the reaction completion liquid is filtered and dried after standing and crystallizing, and 4,4'-dihydroxybiphenyl is obtained. The present invention can improve the catalytic efficiency of the de-tert-butylation reaction, improve product yield, purity and color, and can effectively separate and recover the isobutylene produced in the reaction process, which is green and environmentally friendly.

Description

Technical Field

[0001] The invention relates to the technical field of 4,4'-dihydroxybiphenyl preparation, and in particular to a method and device for synthesizing 4,4'-dihydroxybiphenyl. Background Art

[0002] 4,4'-dihydroxybiphenyl (DOD), also known as 4,4'-biphenyldiphenol, 4,4'-diphenol, 4,4'-biphenyl alcohol, etc., is commonly known as antioxidant 4,4'-dihydroxybiphenyl. 4,4'-dihydroxybiphenyl is a widely used fine chemical that can be used as an antioxidant for rubber and plastics, an oil stabilizer, and a basic raw material for the synthesis of new functional materials. Due to its excellent heat resistance, 4,4'-dihydroxybiphenyl can be used as a modified monomer for polyurethane, epoxy resin, polyester, etc. Liquid crystal polymers produced using it as a raw material are widely used in electronics, telecommunications, aerospace, composite materials, etc.

[0003] Liquid Crystal Polyester (LCP) is a new type of high-performance engineering plastic developed in the 1980s, referred to as LCP. LCP has a very unique molecular structure and thermal behavior, which makes it widely used in high-tech fields such as electrical electronics, aerospace, and optical fiber, and has developed very rapidly. Liquid crystal polymers can also play a role in fiber reinforcement and synthesize blended materials with a variety of plastics. The rigidity, strength and heat resistance of this blended material have been greatly improved. Due to the excellent performance and wide application range of LCP, major LCP manufacturers have invested heavily in research and development in order to expand the market and gain a larger market share. Among them, Asia is the fastest growing market for LCP demand in the world. Many scientific research institutions and universities in my country have set up factories for industrial production. However, as a monomer of high molecular liquid crystal polymer, it needs to have a very high purity. The domestic high-purity 4,4'-dihydroxybiphenyl market has been in short supply. The research and development of high-purity 4,4'-dihydroxybiphenyl has a very broad prospect.

[0004] Yang Shanyue et al. used high temperature to carry out the de-tert-butylation reaction, placed the oxidative coupling reduction product of 2,6-di-tert-butylphenol, 3,3',5,5'-tetra-tert-butylbiphenol (TBBP), in a reactor, heated to 300°C to remove the raw materials, then heated to 320°C for 4h to de-tert-butylate, and then distilled under reduced pressure to obtain 4,4'-biphenol. This method is simple to operate, but the reaction conditions are harsh and the equipment requirements are strict, so it is not suitable for industrial production.

[0005] Jiang Zhongliang and others dissolved 3,3',5,5'-tetra-tert-butylbiphenol, the oxidative coupling reduction product of 2,6-di-tert-butylphenol, in m-xylene, used p-toluenesulfonic acid as a catalyst, and heated the reaction to 130-140°C under nitrogen protection. The product yield was about 80%, the crude product had low purity and poor color, and required further refining to meet the needs of high molecular liquid crystal polymers.

[0006] In summary, in the prior art, the de-tert-butylation method of 3,3',5,5'-tetra-tert-butylbiphenol, the oxidative coupling reduction product of 2,6-di-tert-butylphenol, is a more mainstream method for preparing 4,4'-dihydroxybiphenyl. However, this method has more steps, more types of reagents are added, and the yield is relatively low. Therefore, it is necessary to improve the method to improve the catalytic efficiency, product yield, purity and chromaticity. In addition, during the de-tert-butylation reaction, nitrogen needs to be introduced for protection. The nitrogen and isobutylene generated by the reaction form a mixed gas that is discharged from the reactor, which will cause pollution to the environment. Therefore, a synthesis device capable of separating and recovering nitrogen and isobutylene is required. Summary of the invention

[0007] To solve at least one of the above problems, the present invention provides a method for synthesizing 4,4'-dihydroxybiphenyl, comprising the following steps:

[0008] Step S100, uniformly mixing the solvent and the boiling point aid to obtain a mixed solvent;

[0009] Step S200, 3,3',5,5'-tetra-tert-butylbiphenol and a mixed solvent are mixed and stirred uniformly to obtain a first solution;

[0010] Step S300, mixing the Lewis acid and the reducing auxiliary agent with the mixed solvent and stirring them uniformly to obtain a second solution;

[0011] Step S400, placing the first solution into a synthesis device, stirring under nitrogen protection, heating to a reaction temperature, and then dropping the second solution into the first solution. After the dropping is complete, the reaction is continued at the reaction temperature, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed solution;

[0012] Step S500, the reaction solution is allowed to stand at a precipitation temperature, and after crystals are precipitated, they are filtered and dried to obtain 4,4'-dihydroxybiphenyl.

[0013] In the above technical scheme, the solvent and the boiling point auxiliary agent are mixed to obtain a mixed solvent with a boiling point greater than the reaction temperature. Of course, when the boiling point of the solvent itself is greater than the reaction temperature (such as a sulfone solvent), there is no need to add a boiling point auxiliary agent; 3,3',5,5'-tetra-tert-butylbiphenol is dissolved in part of the mixed solvent, and the Lewis acid and the reducing auxiliary agent as a catalyst are dissolved in the remaining part of the mixed solvent, and then the two are mixed by dropwise addition under a nitrogen atmosphere to perform a de-tert-butylation reaction of 3,3',5,5'-tetra-tert-butylbiphenol. During the reaction, the de-tert-butylation reaction is carried out. The tert-butyl group is free in the mixed solvent. The tert-butyl group is unstable in the mixed solvent and will be quickly converted into gaseous isobutylene and escape. Since the mixed solvent is continuously added to the reaction solution in a dropwise manner, the tert-butyl group can be quickly captured by the added mixed solvent, and the free tert-butyl group content in the reaction solution is greatly reduced, which promotes the reaction to be complete. At the same time, the reducing auxiliary agent can inhibit the generation of oxidation products during the reaction, and no isomers or by-products that are difficult to remove are generated. After the reaction is completed, high-purity and good-color 4,4'-dihydroxybiphenyl can be directly obtained.

[0014] Preferably, in step S100, the solvent is at least one of m-xylene, mixed xylenes, partial trimethylol, mixed trimethylol, cyclopentane sulfone and dimethyl sulfoxide; the boiling point aid is at least one of tridecane, tetradecane and pentadecane; in step S300, the Lewis acid is at least one of sulfuric acid, p-toluenesulfonic acid and methanesulfonic acid; the reducing auxiliary agent is at least one of thiosulfate compounds, sulfite compounds, metal borohydride compounds, hypophosphorous acid compounds and phosphoric acid compounds.

[0015] Preferably, in step S100, the mass ratio of the solvent to the boiling point aid is 1:(0-1); the mass ratio of the mixed solvent in step S100 to the mixed solvent in step S200 is 1:(2-4); in step S300, the amount of Lewis acid added is 0.5-5wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol; the amount of reducing auxiliary agent added is 0.5-5wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol.

[0016] Preferably, in step S100, the mass ratio of the solvent to the boiling point aid is 1:(2 / 3-1), the mass ratio of the mixed solvent in step S100 to the mixed solvent in step S200 is 1:(2-2.75), and in step S300, the amount of Lewis acid added is (1-1.5) wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol; the amount of reducing aid added is (1-2) wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol.

[0017] Preferably, in step S400, the reaction temperature is 120-180°C, the second solution is added dropwise for 5-80 minutes, and the reaction time is 1-8 hours.

[0018] Preferably, in step S400, the reaction temperature is 150-160°C, the dropwise addition time of the second solution is 53-65 minutes, and the reaction time is 2.8-3 hours.

[0019] Preferably, in step S400, the stirring speed is 100-800 rpm, the nitrogen flow rate is 25-1000 mL / min, and in step S500, the crystal precipitation temperature is -10-25°C, the crystal precipitation time is 1-15 h, the drying temperature is 60-120°C, and the drying time is 1-6 h.

[0020] The present invention provides a synthesis device of 4,4'-dihydroxybiphenyl, which is used for synthesizing a reaction completion liquid in step S400. The synthesis device comprises a stirred reactor, which is respectively connected to a dropping tank and an isobutylene separation device, wherein a flow valve is provided on the dropping tank, and the isobutylene separation device comprises a first separation tank filled with an isobutylene solvent for separating isobutylene and nitrogen, and a second separation tank for separating isobutylene and the isobutylene solvent.

[0021] Preferably, the second separation tank comprises a heating tank, the top of the heating tank is provided with an isobutylene solution inlet and an isobutylene gas outlet, the bottom is provided with an isobutylene solvent outlet, the outer wall is covered with a phase change heat storage layer, and the outer wall of the phase change heat storage layer is provided with a heating coil connected to the nitrogen / isobutylene outlet of the stirred reactor.

[0022] Preferably, the first separation tank comprises a cooling tank, an isobutylene solvent is arranged inside the cooling tank, a liquid inlet pipe and a nitrogen / isobutylene inlet pipe extending below the liquid surface are arranged on the top, an isobutylene solution outlet is arranged at the bottom, a nitrogen outlet is arranged above the side wall, and a cooling coil and an air inlet coil tightly fitted to each other are arranged on the outer wall, one end of the air inlet coil is connected to the heating coil, and the other end is connected to the nitrogen / isobutylene inlet pipe, and the liquid inlet pipe is connected to the isobutylene solvent outlet through a pump.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] 1. Mixing the solvent and the boiling point additive can obtain a mixed solvent with a boiling point greater than the reaction temperature, thereby avoiding the azeotropic formation of the solvent and isobutylene during the reaction and facilitating the separation and recovery of isobutylene;

[0025] 2. The Lewis acid catalyst and the reducing auxiliary agent work synergistically, which can increase the rate of the de-tert-butylation reaction while inhibiting the oxidation reaction during the de-tert-butylation process, thereby improving the purity and color of the reaction product;

[0026] 3. Dissolve 3,3',5,5'-tetra-tert-butylbiphenol in a mixed solvent, dissolve a Lewis acid and a reducing auxiliary agent as a catalyst in the mixed solvent, and then, under a nitrogen atmosphere, capture the tert-butyl group removed by the reaction by dropwise adding the mixed solvent and the catalyst, thereby accelerating the conversion rate of the tert-butyl group to isobutylene and promoting the complete reaction without generating isomers or by-products that are difficult to remove. After the reaction is completed, high-purity and good-color 4,4'-dihydroxybiphenyl can be directly obtained;

[0027] 4. The synthesis device is equipped with a dropping tank and an isobutylene separation device. The dropping tank can effectively control the dropping time, improve the reaction control accuracy, and obtain a high-purity reaction product. The isobutylene separation device first passes the nitrogen and isobutylene mixed gas discharged during the reaction into a first separation tank containing an isobutylene solvent to separate the isobutylene solution from the nitrogen, and then passes the obtained isobutylene solution into a second separation tank to separate the isobutylene and isobutylene solvent by heating, which effectively avoids environmental pollution, saves energy consumption, and reduces production costs;

[0028] In summary, the present invention can improve the catalytic efficiency of the de-tert-butylation reaction, improve the product yield, purity and color, and can effectively separate and recover the isobutylene generated in the reaction process, which is green and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the structure of the synthesis device in the present invention;

[0030] Figure 2 is a three-dimensional cross-sectional view of the first separation tank;

[0031] Figure 3 This is the exploded view of the center tube;

[0032] Figure 4 It is a three-dimensional cross-sectional view of the first separation tank from another angle.

[0033] Description of reference numerals:

[0034] 1. Stirring reactor, 11. Second solution feed port, 12. Nitrogen / isobutylene outlet, 13. Isobutylene detector, 2. Dropping tank, 21. Flow valve, 3. First separation tank, 31. Cooling tank, 311. Tank body, 3111. First separation zone, 3112. Second separation zone, 3113. Third separation zone, 312. Tank cover, 3121. Closed cavity, 3122. Sliding hole, 32. Liquid inlet pipe, 321. Main pipe, 322. Branch pipe, 33. Nitrogen / isobutylene inlet pipe, 34. Isobutylene solution outlet, 35. Nitrogen outlet, 36. Cooling Coil, 37, air inlet coil, 38, cylinder, 4, second separation tank, 41, heating tank, 42, isobutylene solution inlet, 43, isobutylene gas outlet, 44, isobutylene solvent outlet, 45, phase change heat storage layer, 46, heating coil, 5, center tube, 51, cylinder, 511, upper cover, 512, small cylindrical section, 513, conical section, 514, large cylindrical section, 52, partition, 521, sealing plug, 53, circular filter screen, 54, arc filter screen, 6, first bellows, 7, second bellows, 8, disc gas distributor, 9, arc gas distributor. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is described below in conjunction with the accompanying drawings and embodiments:

[0036] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so that people familiar with this technology can understand and read them, and are not used to limit the conditions under which the present invention can be implemented. Any structural modification, change in proportional relationship or adjustment of size should fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0037] At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content. Example 1

[0038] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0039] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0040] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0041] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0042] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0043] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 2

[0044] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0045] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of tetradecane are uniformly mixed to obtain a mixed solvent;

[0046] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0047] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0048] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0049] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 3

[0050] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0051] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of tridecane are uniformly mixed to obtain a mixed solvent;

[0052] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0053] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0054] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0055] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 4

[0056] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0057] Step S100, 15 parts by mass of m-xylene, 10 parts by mass of pentadecane and 5 parts by mass of tetradecane are uniformly mixed to obtain a mixed solvent;

[0058] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0059] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0060] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0061] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 5

[0062] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0063] Step S100, 15 parts by mass of m-xylene, 8 parts by mass of pentadecane, 4 parts by mass of tetradecane and 3 parts by mass of tridecane are uniformly mixed to obtain a mixed solvent;

[0064] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0065] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0066] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0067] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 6

[0068] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0069] Step S100, 15 parts by mass of m-xylene, 5 parts by mass of pentadecane, 8 parts by mass of tetradecane and 2 parts by mass of tridecane are uniformly mixed to obtain a mixed solvent;

[0070] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0071] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0072] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0073] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 7

[0074] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0075] Step S100, 15 parts by mass of m-xylene, 12 parts by mass of tetradecane and 3 parts by mass of tridecane are uniformly mixed to obtain a mixed solvent;

[0076] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0077] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0078] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0079] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 8

[0080] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0081] Step S100, 18 parts by mass of m-xylene and 12 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0082] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0083] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0084] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0085] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 9

[0086] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0087] Step S100, 15 parts by mass of mixed xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0088] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0089] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0090] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0091] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 10

[0092] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0093] Step S100, 15 parts by mass of trimethylol and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0094] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0095] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0096] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0097] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 11

[0098] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0099] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0100] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 8 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0101] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 22 parts by mass of a mixed solvent to obtain a second solution;

[0102] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0103] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 12

[0104] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0105] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0106] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0107] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0108] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 100 mL / min, the stirring speed is 400 rpm, heating to 150° C. and then dripping the second solution into the first solution, the dripping time is 65 min, and after the dripping is completed, continuing the reaction at 150° C. for 3 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0109] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 13

[0110] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0111] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0112] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0113] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0114] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 100 mL / min, the stirring speed is 400 rpm, heating to 160° C. and then dripping the second solution into the first solution, the dripping time is 53 min, and after the dripping is completed, continuing the reaction at 160° C. for 2.8 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0115] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 14

[0116] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0117] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0118] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0119] Step S300, 0.45 parts by mass of sulfuric acid and 0.6 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0120] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 600 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0121] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 15

[0122] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0123] Step S100, 20 parts by mass of m-xylene and 10 parts by mass of pentadecane are mixed evenly to obtain a mixed solvent;

[0124] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0125] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0126] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0127] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Example 16

[0128] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0129] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0130] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 6 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0131] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 24 parts by mass of a mixed solvent to obtain a second solution;

[0132] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0133] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 17

[0134] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0135] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0136] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0137] Step S300, 0.15 parts by mass of sulfuric acid and 0.15 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0138] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0139] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 18

[0140] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0141] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0142] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0143] Step S300, 1.5 parts by mass of sulfuric acid and 1.5 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0144] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0145] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 19

[0146] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0147] Step S100, 15 parts by mass of trimethylolbenzene and 15 parts by mass of tridecane are uniformly mixed to obtain a mixed solvent;

[0148] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0149] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0150] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0151] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 20

[0152] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0153] Step S100, using 30 parts by mass of sulfolane as a mixed solvent;

[0154] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0155] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0156] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0157] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 21

[0158] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0159] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0160] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0161] Step S300, 0.3 parts by mass of p-toluenesulfonic acid and 0.3 parts by mass of sodium thiosulfate are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0162] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0163] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 22

[0164] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0165] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0166] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0167] Step S300, 0.3 parts by mass of methanesulfonic acid and 0.3 parts by mass of sodium hypophosphite are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0168] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0169] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 23

[0170] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0171] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0172] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0173] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0174] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 100 mL / min, the stirring speed is 400 rpm, heating to 155° C. and then dripping the second solution into the first solution, the dripping time is 5 min, and after the dripping is completed, continuing the reaction at 155° C. for 8 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0175] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 24

[0176] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0177] Step S100, 15 parts by mass of xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0178] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0179] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0180] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 100 mL / min, the stirring speed is 400 rpm, heating to 120° C. and then dripping the second solution into the first solution, the dripping time is 80 min, and after the dripping is completed, continuing the reaction at 120° C. for 2 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0181] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 25

[0182] This embodiment prepares a 4,4-dihydroxybiphenyl, comprising the following steps:

[0183] Step S100, using 30 parts by mass of dimethyl sulfoxide as a mixed solvent;

[0184] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0185] Step S300, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of a mixed solvent to obtain a second solution;

[0186] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 400 mL / min, the stirring speed is 800 rpm, heating to 180° C. and then dripping the second solution into the first solution, the dripping time is 30 min, and after the dripping is completed, continuing the reaction at 180° C. for 4 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0187] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl. Embodiment 26

[0188] Combined with Figure 1-4 The present embodiment provides a synthesis device of 4,4'-dihydroxybiphenyl, the synthesis device comprising a stirred reactor 1, the stirred reactor 1 is respectively connected to a dropping tank 2 and an isobutylene separation device, the dropping tank 2 is provided with a flow valve 21, the isobutylene separation device comprises a first separation tank 3 filled with isobutylene solvent for separating isobutylene and nitrogen and a second separation tank 4 for separating isobutylene and isobutylene solvent.

[0189] In the above technical scheme, the unmentioned parts are all conventional settings in the prior art. For example, the top of the stirred reactor 1 is provided with a first solution feed port, a second solution feed port 11, a nitrogen inlet, a stirring drive motor and a nitrogen / isobutylene outlet 12 provided with an isobutylene detector 13, a stirring paddle is provided inside, a heating jacket is provided on the side wall, and a discharge port is provided at the bottom; the second solution feed port 11 is connected to the dropping tank 2, the nitrogen / isobutylene outlet 12 is connected to the isobutylene separation device, and switch valves can be provided on each connecting pipeline of the stirred reactor 1, the dropping tank 2 and the isobutylene separation device in a conventional manner; the stirred reactor 1 is filled with the first solution, the dropping tank 2 is filled with the second solution, the dripping speed of the second solution into the stirred reactor 1 is controlled by the flow valve 21, the isobutylene detector 13 detects the isobutylene content in the mixed gas discharged from the nitrogen / isobutylene outlet 12, and when the isobutylene content is zero , the reaction is finished; the isobutylene separation device is used to separate the discharged isobutylene and nitrogen. The isobutylene separation device can directly use a condenser to liquefy isobutylene and separate it from nitrogen. However, the temperature of the mixed gas of isobutylene and nitrogen is above 100°C when it is discharged, and the condensation point of isobutylene is -140°C. Therefore, the energy consumption is extremely high when the condenser is used for condensation separation. Based on this, the first separation tank 3 and the second separation tank 4 are used in this embodiment to separate. First, the isobutylene in the mixed gas is dissolved in the isobutylene solvent in the first separation tank 3 to form an isobutylene solution, the isobutylene is separated from the nitrogen, and then the isobutylene solution is passed into the second separation tank 4. The isobutylene and the isobutylene solvent are separated by heating, which greatly saves energy consumption. The isobutylene solvent uses a liquid organic solvent with a large difference in boiling point from isobutylene, including but not limited to carbon tetrachloride and tetrahydrofuran.

[0190] The second separation tank 4 includes a heating tank 41, the top of the heating tank 41 is provided with an isobutylene solution inlet 42 and an isobutylene gas outlet 43, the bottom is provided with an isobutylene solvent outlet 44, the outer wall is covered with a phase change heat storage layer 45, and the outer wall of the phase change heat storage layer 45 is provided with a heating coil 46 connected to the nitrogen / isobutylene outlet 12 of the stirred reactor 1.

[0191] In the above technical scheme, the high-temperature mixed gas flowing out of the stirred reactor 1 is passed into the heating coil 46, the phase change heat storage layer 45 absorbs the heat of the mixed gas in the heating coil 46 to store energy, the temperature of the mixed gas is reduced, and the mixed gas after cooling is passed into the first separation tank 3, the solubility of low-temperature isobutylene in the isobutylene solvent is increased, the separation efficiency is improved, and the separated nitrogen is collected. After the separation is completed, the isobutylene solution in the first separation tank 3 is passed into the second separation tank 4, at which time the phase change heat storage layer 45 releases heat energy to heat the isobutylene solution, so that isobutylene is separated from the isobutylene solvent, the separated isobutylene is collected, and the isobutylene solvent is passed into the first separation tank 3 again for reuse. The material selection of the phase change heat storage layer needs to match the boiling point of the isobutylene solvent, so as to avoid the temperature of the phase change heat storage layer being too high when releasing heat and exceeding the boiling point of the isobutylene solvent.

[0192] The first separation tank 3 includes a cooling tank 31, in which isobutylene solvent is arranged, a liquid inlet pipe 32 and a nitrogen / isobutylene inlet pipe 33 extending below the liquid surface are arranged on the top, an isobutylene solution outlet 34 is arranged on the bottom, a nitrogen outlet 35 is arranged on the top of the side wall, and a cooling coil 36 and an air inlet coil 37 that fit closely to each other are arranged on the outer wall, one end of the air inlet coil 37 is connected to the heating coil 46, and the other end is connected to the nitrogen / isobutylene inlet pipe 33, and the liquid inlet pipe 32 is connected to the isobutylene solvent outlet 44 through a pump.

[0193] In the above technical solution, the mixed gas enters the air inlet coil 37 from the heating coil 46, and then enters the first separation tank 3 from the nitrogen / isobutylene inlet pipe 33. A cooling coil 36 is arranged on the first separation tank 3. The cooling coil 36 can be connected to a low-energy cooling water circulation system. The cooling coil 36 cools the air inlet coil 37 and the first separation tank 3 at the same time, so that the temperature of the mixed gas and the isobutylene solvent is further reduced, and the solubility and separation efficiency of isobutylene are further improved.

[0194] The cooling tank 31 adopts a three-stage gradient separation mode. A central tube 5 is provided in the cooling tank 31. The central tube 5 includes a cylinder 51 with an opening at the bottom and two partitions 52 vertically arranged on the outer wall of the cylinder 51. The central tube 5 seals and separates the cooling tank 31 into a first separation zone 3111 located at the center and a second separation zone 3112 and a third separation zone 3113 located on both sides.

[0195] The nitrogen / isobutylene inlet pipe 33 is arranged in the first separation zone 3111, the nitrogen outlet 35 is arranged in the third separation zone 3113, the first bellows 6 connects the gas phase zone of the first separation zone 3111 and the liquid phase zone of the second separation zone 3112, and the second bellows 7 connects the gas phase zone of the second separation zone 3112 and the liquid phase zone of the third separation zone 3113.

[0196] In the above technical scheme, the cooling tank 31 is separated into three separation zones by the central tube 5, the mixed gas is firstly separated in the first separation zone 3111, the mixed gas after the first separation enters the second separation zone 3112 through the first bellows 6, and is separated in the second separation zone 3112 for the second separation, and the mixed gas after the second separation enters the third separation zone 3113 through the second bellows 7, and is separated in the third separation zone 3113 for the third separation, and the nitrogen is collected after the separation is completed, and the separation is performed by the three-stage gradient separation mode, which can improve the separation effect of isobutylene and nitrogen. The second bellows 7 can directly pass through the partition 52 to connect to the gas phase zone of the second separation zone 3112, or the structure in the present embodiment can be adopted, and an arc-shaped air guide pipe is set at the air inlet end of the second bellows 7, and the air guide pipe is coaxially fixed on the central tube 5, and two through holes connected to the gas phase zone of the second separation zone 3112 are respectively set on the two partitions 52, and the two ends of the air guide pipe are sealed and docked with the through holes on the partition 52, and the center is connected to the tube body of the second bellows 7.

[0197] The nitrogen / isobutylene inlet pipe 33 is connected to the disc gas distributor 8, the first bellows 6 and the second bellows 7 are respectively connected to the arc-shaped gas distributor 9, and the cylinder 51 includes an upper cover 511, a small cylindrical section 512, a conical section 513 and a large cylindrical section 514 from top to bottom. The inner ring wall of the small cylindrical section 512 is provided with a circular filter screen 53, and the outer ring wall is provided with two arc-shaped filter screens 54. The circular filter screen 53 and the arc-shaped filter screen 54 are located above the disc gas distributor 8 and the arc-shaped gas distributor 9 in the liquid phase region, and the large cylindrical section 514 and the partition 52 are sealed and inserted between the two arc-shaped gas distributors 9.

[0198] In the above technical scheme, the disc gas distributor 8 and the arc-shaped gas distributor 9 are used together to cover the bottom of the cooling tank 31, further improving the gas distribution effect. At the same time, the two arc-shaped gas distributors 9 can clamp and hold the central tube 5, position the central tube 5, and improve the stability of the use of the central tube 5. The cylinder body 51 adopts a narrow upper and wide lower structural design, which can improve the primary separation effect in the first separation zone 3111 and reduce the subsequent separation pressure. The circular filter screen 53 and the arc-shaped filter screen 54 can refine the bubbles in the liquid phase and further improve the separation effect. In this embodiment, the disc gas distributor 8 adopts a structure connected by multiple stages of circular rings, covering the bottom of the first separation zone 3111. It should be noted that the disc gas distributor 8 can adopt any disc-type gas distribution structure in the prior art, as long as it can cover the bottom of the first separation zone 3111. The arc-shaped gas distributor 9 adopts an arc-shaped structure, the inner wall of which is close to the central tube 5, and the outer wall and the bottom are close to the cooling tank 31, covering the bottom of the second separation zone 3112 and the third separation zone 3113.

[0199] In a specific structure, a sealing plug 521 for sealing the isobutylene solution outlet 34 is provided at the bottom of a partition 52, the cooling tank 31 includes a tank body 311 and a tank cover 312, the tank cover 312 is provided with a closed cavity 3121 for the central tube 5 to slide up and down, the bottom is provided with a sliding hole 3122 for slidingly matching with the central tube 5, the top is provided with a cylinder 38, a liquid inlet pipe 32 and a nitrogen / isobutylene inlet pipe 33, the output end of the cylinder 38 is connected to the central tube 5, the liquid inlet pipe 32 includes a main pipe 321 connected to the isobutylene solvent outlet 44 and three branch pipes 322 connected to the first separation zone 3111, the second separation zone 3112 and the third separation zone 3113.

[0200] In the above technical scheme, the central tube 5 can move up and down under the control of the cylinder 38. When the mixed gas in the cooling tank 31 is separated, the cylinder 38 controls the central tube 5 to move up, and the sealing plug 521 at the bottom of the partition 52 is away from the isobutylene solution outlet 34. The first separation zone 3111, the second separation zone 3113 and the third separation zone 3113 are connected at the bottom. The isobutylene solutions in the three separation zones are mixed and flow out from the isobutylene solution outlet 34, which improves the discharge efficiency. After the discharge is completed, the cylinder 38 controls the central tube 5 to move down, and the sealing plug at the bottom of the partition 52 blocks the isobutylene solution outlet 34. Three independent separation zones are re-formed inside the cooling tank 31. The isobutylene solution outlet 34 is arranged below the partition 52, and its opening and closing is controlled by the partition 52, which can reduce the number of switch valves used.

[0201] Comparative Example 1

[0202] This comparative example prepares a 4,4-dihydroxybiphenyl, which is different from Example 1 in that the reducing auxiliary agent sodium borohydride is not added in step S300, and comprises the following steps:

[0203] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0204] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of a mixed solvent are mixed and stirred to obtain a first solution;

[0205] Step S300, 0.3 parts by mass of sulfuric acid and 20 parts by mass of a mixed solvent are mixed and stirred uniformly to obtain a second solution;

[0206] Step S400, placing the first solution into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and then dripping the second solution into the first solution for 60 min, and continuing the reaction at 155° C. for 3 h after the dripping is completed, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0207] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl.

[0208] Comparative Example 2

[0209] This comparative example prepares a 4,4-dihydroxybiphenyl, which is different from Example 1 in that a conventional one-time addition method is used for the reaction instead of a dropwise addition method, and includes the following steps:

[0210] Step S100, 15 parts by mass of m-xylene and 15 parts by mass of pentadecane are uniformly mixed to obtain a mixed solvent;

[0211] Step S200, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol, 0.3 parts by mass of sulfuric acid and 30 parts by mass of a mixed solvent are mixed and stirred to obtain a reaction solution;

[0212] Step S300, placing the reaction liquid into a synthesis device, starting stirring under nitrogen protection, with a nitrogen flow rate of 100 mL / min and a stirring speed of 400 rpm, heating to 155° C. and reacting for 4 hours, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed liquid;

[0213] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl.

[0214] Comparative Example 3

[0215] This comparative example prepares a 4,4-dihydroxybiphenyl, which differs from Example 1 in that no boiling point auxiliary agent pentadecane is added, and comprises the following steps:

[0216] Step S100, 30 parts by mass of 3,3',5,5'-tetra-tert-butylbiphenol and 10 parts by mass of m-xylene are mixed and stirred to obtain a first solution;

[0217] Step S200, 0.3 parts by mass of sulfuric acid and 0.3 parts by mass of sodium borohydride are mixed and stirred with 20 parts by mass of m-xylene to obtain a second solution;

[0218] Step S300, placing the first solution into a synthesis device, starting stirring under nitrogen protection, the nitrogen flow rate is 100 mL / min, the stirring speed is 400 rpm, heating to 155° C. and then dripping the second solution into the first solution, the dripping time is 60 min, and after the dripping is completed, continuing the reaction at 155° C. for 3 h, and the reaction is terminated when no isobutylene gas is generated, to obtain a reaction completed liquid;

[0219] Step S500, the reaction solution is allowed to stand at 0°C for 12 hours, and after crystals are precipitated, they are filtered and dried at 100°C for 2 hours to obtain 4,4'-dihydroxybiphenyl.

[0220] Results

[0221] The reaction products of Examples 1-25 and Comparative Examples 1-3 were tested. The test results are shown in Table 1.

[0222] Table 1 Reaction yield, product purity and color detection results

[0223]

[0224] As can be seen from Table 1, the synthesis method of the present invention can obtain white 4,4-dihydroxybiphenyl with high yield and high purity, especially by using the reaction parameters in Examples 1 to 14, that is, the mass ratio of the solvent to the boiling point aid in step S100 is 1: (2 / 3-1), the mass ratio of the mixed solvent in step S100 to the mixed solvent in step S200 is 1: (2-2.75), the amount of Lewis acid added in step S300 is (1-1.5) wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol; the amount of reducing auxiliary agent added is (1-1.5) wt% of the mass of 3,3',5,5'-tetra-tert-butylbiphenol; The mass of hydroquinone is (1-2) wt%, the reaction temperature in step S400 is 150-160°C, the dripping time of the second solution is 53-65min, and the reaction time is 2.8-3h. A pure white product with a yield of >96% and a purity of >99.6% can be obtained; in comparative example 1, no reducing auxiliary agent is added, and the obtained product has low purity and poor color. In comparative example 2, the dripping method is not adopted, but the reaction raw materials are added at one time for reaction. The obtained product has low purity and poor color. In comparative example 3, no boiling point auxiliary agent is added, and only meta-xylene is used as the solvent. The obtained product has low yield, low purity and poor color.

[0225] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention shall be equivalent replacement modes and shall be included in the protection scope of the present invention.

Claims

1. A method for synthesizing 4,4'-dihydroxybiphenyl, characterized in that: The following steps are involved: Step S100, uniformly mixing a solvent and a boiling point aid to obtain a mixed solvent; the solvent is at least one of m-xylene, mixed xylenes, partial trimethylolenes and mixed trimethylolenes; the boiling point aid is at least one of tridecane, tetradecane and pentadecane; Step S200, 3,3',5,5'-tetra-tert-butylbiphenol and a mixed solvent are mixed and stirred uniformly to obtain a first solution; Step S300, mixing and stirring the Lewis acid and the reducing auxiliary agent with the mixed solvent to obtain a second solution; the Lewis acid is at least one of sulfuric acid, p-toluenesulfonic acid and methanesulfonic acid; the reducing auxiliary agent is at least one of potassium thiosulfate, sodium bisulfite, sodium borohydride and sodium hypophosphite; Step S400, placing the first solution into a synthesis device, stirring under nitrogen protection, heating to a reaction temperature, and then dropping the second solution into the first solution. After the dropping is complete, the reaction is continued at the reaction temperature, and the reaction is terminated when no isobutylene gas is generated, thereby obtaining a reaction-completed solution; Step S500, the reaction solution is allowed to stand at a precipitation temperature, and after crystals are precipitated, they are filtered and dried to obtain 4,4'-dihydroxybiphenyl.

2. The method for synthesizing 4,4'-dihydroxybiphenyl according to claim 1, characterized in that: In step S400, the reaction temperature is 120-180°C, the second solution is added dropwise for 5-80 minutes, and the reaction time is 1-8 hours.

3. The method for synthesizing 4,4'-dihydroxybiphenyl according to claim 1, characterized in that: In step S400, the reaction temperature is 150-160°C, the second solution is added dropwise for 53-65 minutes, and the reaction time is 2.8-3 hours.

4. The method for synthesizing 4,4'-dihydroxybiphenyl according to claim 1, characterized in that: In step S400, the stirring speed is 100-800 rpm, the nitrogen flow rate is 25-1000 mL / min, and in step S500, the crystal precipitation temperature is -10-25°C, the crystal precipitation time is 1-15 h, the drying temperature is 60-120°C, and the drying time is 1-6 h.

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