Disclosure of Invention
The invention provides a method for synthesizing 4,4 '-dihydroxybiphenyl, which has the advantages of high efficiency, high yield and low tar byproduct, and aims to solve the problems of low yield, low reaction efficiency and environmental pollution of the existing method for synthesizing 4, 4' -dihydroxybiphenyl.
A method for synthesizing 4, 4' -dihydroxybiphenyl using a loop reactor, the method comprising the steps of:
firstly, adding phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding a Lewis acid catalyst, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system at the temperature of 90-120 ℃ for 4-8 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in an organic solvent, sequentially adding an alkali catalyst and an oxidant, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 50-100 ℃, reacting for 2-4 h, then heating to 180-200 ℃, reacting for 3-5 h, cooling, and filtering to obtain tetra-tert-butyl biphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent, adding a strong acid catalyst, controlling the temperature to be 120-160 ℃ for reaction, then obtaining 4, 4' -dihydroxy biphenyl by adopting a recrystallization method or a sublimation method, cooling and recovering isobutene generated by the reaction, and completing the process;
step two, the structural formula of the di-tert-butylphenol is as follows:
step three, the structural formula of the tetra-tert-butyl biphenyl diphenol is as follows:
fourthly, the structural formula of the 4, 4' -dihydroxybiphenyl is as follows:
the reaction scheme equation is as follows:
among the above-mentioned technical scheme, the reation kettle who disposes return circuit reaction system includes reation kettle and return circuit reaction system, and return circuit reaction system includes venturi ejector, return circuit circulating pump and heat exchanger. Under the action of the loop circulating pump, the fluid in the kettle is continuously sprayed out through the nozzle of the venturi ejector, and at the nozzle, gas is continuously sucked due to low pressure, and reaction liquid and reaction gas are continuously mixed in the venturi ejector, so that the reaction efficiency is accelerated, the mass transfer ratio (the volume ratio of the gas to the liquid) of the reaction is 0.5-2, and the mass transfer ratio of the common stirring reaction is 0.15-0.35, and the reaction efficiency is greatly improved by a loop reaction system under the comparison.
Optionally, under the condition that the circulating pump is not started, only stirring is started to carry out the reaction, and the rotating speed is 30-60 r/min.
In the above technical scheme, the strong acid catalyst and the mixed solvent in the step four can be recycled for further use.
In the technical scheme, the isobutene generated by the reaction in the fourth step can be recovered by refrigeration and used for the reaction of the second step and phenol to synthesize the di-tert-butylphenol.
The invention has the beneficial effects that:
(1) the invention provides a method for synthesizing 4, 4' -dihydroxybiphenyl by adopting a loop reactor, wherein a reaction device is provided with a loop reaction system, so that the mass transfer rate of gas-liquid phase reaction can be greatly improved, the reaction efficiency is improved, the reaction time can be shortened by 60 percent, the energy consumption of the reaction is correspondingly reduced, and the production cost is reduced. Meanwhile, the external heat exchanger can take away part of reaction heat release, reduce reaction risk and improve the safety coefficient of the reaction.
(2) According to the invention, the mixed solvent of alkane and aromatic ring is used in the tetra-tert-butyl diphenol dealkylation reaction, the reaction temperature is low (120-160 ℃), the byproduct tar is avoided being generated under the high temperature (200 ℃), and meanwhile, the self-polymerization of isobutene molecules generated by the reaction can be avoided and isobutene can be recycled for the reaction with phenol, so that the product economy is improved. After the 4, 4' -dihydroxybiphenyl product prepared by the method is refined in a recrystallization or sublimation mode, the product purity is more than 99.5 percent, and the requirements of polymer-grade industrial products are met.
In the invention, the used strong acid catalyst has a generally higher price, and can be recovered by adding water to dissolve the catalyst after the reaction is finished and the temperature is reduced, so that the method accords with the concept of green chemistry and can also reduce the production cost.
The verification proves that the total yield of the method is more than 90 percent, and the purity of the high-purity 4, 4' -dihydroxybiphenyl prepared by the method reaches more than 99.5 percent.
The method is used for preparing the 4, 4' -dihydroxybiphenyl.
Detailed Description
The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.
The first embodiment is as follows: the embodiment relates to a method for synthesizing 4, 4' -dihydroxybiphenyl by adopting a loop reactor, which comprises the following steps:
firstly, adding phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding a Lewis acid catalyst, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system at the temperature of 90-120 ℃ for 4-8 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in an organic solvent, sequentially adding an alkali catalyst and an oxidant, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 50-100 ℃, reacting for 2-4 h, then heating to 180-200 ℃, reacting for 3-5 h, cooling, and filtering to obtain tetra-tert-butyl biphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent, adding a strong acid catalyst, controlling the temperature to be 120-160 ℃ for reaction, then obtaining 4, 4' -dihydroxy biphenyl by adopting a recrystallization method or a sublimation method, cooling and recovering isobutene generated by the reaction, and completing the process;
step two, the structural formula of the di-tert-butylphenol is as follows:
step three, the structural formula of the tetra-tert-butyl biphenyl diphenol is as follows:
fourthly, the structural formula of the 4, 4' -dihydroxybiphenyl is as follows:
the second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: step one, a reaction kettle for configuring a loop reaction system comprises a reaction kettle 1 and the loop reaction system, wherein the loop reaction system comprises a Venturi ejector 3, a loop circulating pump 4 and a heat exchanger 2; the venturi ejector 3 is arranged at the top end of the reaction kettle 1, an inlet of the venturi ejector 3 is communicated with an outlet of the heat exchanger 2, an outlet at the bottom of the reaction kettle 1 is communicated with an inlet at the bottom of the heat exchanger 2, and a loop circulating pump 4 is arranged on a pipeline communicated with the outlet at the bottom of the reaction kettle 1 and the inlet at the bottom of the heat exchanger 2. The rest is the same as the first embodiment.
The third concrete implementation mode: the present embodiment differs from the first or second embodiment in that: and step two, the Lewis acid catalyst is one or a mixture of more of ferric chloride, aluminum chloride, zinc chloride, isopropyl aluminum and phenyl aluminum, and the dosage of the Lewis acid catalyst is 0.1-10% of the mass of the phenol. The other is the same as in the first or second embodiment.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: and in the second step, the mass ratio of the isobutene to the phenol is 1: 1.2-1.7. The others are the same as in one of the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: and step three, the organic solvent is ethanol, isopropanol, butanol, isobutanol, amyl alcohol, octanol, ethyl acetate, toluene, xylene, p-methyl phenol or m-methyl phenol, and the dosage of the organic solvent is 200-450% of the mass of the di-tert-butyl phenol. The other is the same as one of the first to fourth embodiments.
The sixth specific implementation mode: the difference between this embodiment and one of the first to fifth embodiments is: and step three, the oxidant is oxygen-containing mixed gas or oxygen, and the oxygen-containing mixed gas is nitrogen and oxygen mixed gas or air. The other is the same as one of the first to fifth embodiments.
The seventh embodiment: the difference between this embodiment and one of the first to sixth embodiments is: and step three, the alkali catalyst is one or a mixture of more of sodium methoxide, sodium ethoxide, sodium tert-butoxide, sodium hydroxide, potassium carbonate, sodium carbonate, diisopropylamine, triethylamine, tetramethylethylenediamine and diethylenetriamine, and the amount of the alkali catalyst is 0.5-5% of the mass of the di-tert-butylphenol. The other is the same as one of the first to sixth embodiments.
The specific implementation mode is eight: the present embodiment differs from one of the first to seventh embodiments in that: the mixed solvent is the mixture of a benzene solvent and an alkane solvent, wherein the mass ratio of the benzene solvent to the alkane solvent is 1: 3-6; the benzene solvent is benzene, toluene or xylene, and the alkane solvent is octane, nonane, decane or undecane. The other is the same as one of the first to seventh embodiments.
The specific implementation method nine: the present embodiment differs from the first to eighth embodiments in that: and fourthly, the mass ratio of the tetra-tert-butyl biphenyl diphenol solution to the mixed solvent is 1 to (2-5.5). The rest is the same as the first to eighth embodiments.
The detailed implementation mode is ten: the present embodiment differs from one of the first to ninth embodiments in that: and step four, the strong acid catalyst is one or a mixture of more of concentrated sulfuric acid, benzenesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid, trifluoromethanesulfonic acid, chlorosulfonic acid and phosphoric acid, and the dosage of the strong acid catalyst is 0.2-20% of the mass of the tetra-tert-butyl diphenol. The other is the same as one of the first to ninth embodiments.
The concrete implementation mode eleven: the present embodiment differs from one of the first to tenth embodiments in that: the purity of the 4, 4' -dihydroxybiphenyl obtained in the fourth step is more than 99.5%. The rest is the same as one of the first to tenth embodiments.
The following examples and comparative experiments were used to verify the beneficial effects of the present invention:
example 1:
this example is a process for the synthesis of 4, 4' -dihydroxybiphenyl using a loop reactor, comprising the steps of:
firstly, adding 500kg of phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding 10kg of aluminum chloride, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 100-120 ℃, and reacting for 6 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 2500kg of isobutanol, adding 44kg of sodium hydroxide, continuously introducing oxygen, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 70-80 ℃, reacting for 2 hours, introducing nitrogen to exhaust oxygen, heating to 180-200 ℃, reacting for 3.5 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl diphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent of toluene and nonane, wherein the mass ratio of toluene to nonane in the mixed solvent is 1: 5; then slowly adding 165kg of concentrated sulfuric acid, controlling the temperature to be 120-135 ℃, reacting for 5 hours, cooling to room temperature, carrying out centrifugal filtration to obtain a crude product, recovering the mixed solvent, recrystallizing the crude product by using ethanol to obtain 416kg of high-purity white crystals of 4, 4' -dihydroxybiphenyl, wherein the purity is 99.8%, and the yield is 84%; freezing and recovering isobutene generated in the reaction.
The liquid chromatogram of the product prepared in this example is shown in FIG. 2, which is obtained by testing Shimadzu LC-20AT apparatus, Lichrospher C18 column (4.6 mm. times.250 mm, 5 μm), mobile phase methanol: 1:1 for water, the sample volume tested was 20 μ L, the detector wavelength was 230nm, as can be seen, there were three characteristic peaks in total, as specified in table 1 below,
TABLE 1
Example 2:
this example is a process for the synthesis of 4, 4' -dihydroxybiphenyl using a loop reactor, comprising the steps of:
firstly, adding 800kg of phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding 2kg of isopropyl aluminum, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 90-110 ℃, and reacting for 4.5 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 4500kg of amyl alcohol, adding 85kg of potassium carbonate, continuously introducing oxygen, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 70-80 ℃, reacting for 3.5 hours, introducing nitrogen to exhaust oxygen, heating to 185-200 ℃, reacting for 4.5 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl diphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent of toluene and undecane, wherein the mass ratio of toluene to undecane in the mixed solvent is 1: 3; slowly adding 17kg of methanesulfonic acid, controlling the temperature to be 130-160 ℃, reacting for 3.5h, cooling to room temperature, performing centrifugal filtration to obtain a crude product, recovering the mixed solvent, recrystallizing the crude product by using ethyl acetate to obtain 720kg of high-purity white crystal 4, 4' -dihydroxybiphenyl, wherein the purity is 99.6%, and the yield is 91%; freezing and recovering isobutene generated in the reaction.
Example 3:
this example is a process for the synthesis of 4, 4' -dihydroxybiphenyl using a loop reactor, comprising the steps of:
firstly, adding 600kg of phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding 6kg of aluminum chloride and 7kg of phenyl aluminum, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 90-110 ℃, and reacting for 4 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 4500kg of octanol, adding 10kg of sodium methoxide, continuously introducing oxygen, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 70-90 ℃, reacting for 2.5 hours, then introducing nitrogen to exhaust oxygen, heating to 185-200 ℃, reacting for 4 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl diphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent of xylene and undecane, wherein the mass ratio of the xylene to the undecane in the mixed solvent is 1: 3; then slowly adding a mixture of 26kg of benzenesulfonic acid and 26kg of p-toluenesulfonic acid, controlling the temperature to be 140-160 ℃, reacting for 3.5h, cooling to room temperature, adding 100kg of water, carrying out centrifugal filtration to obtain a crude product, recovering a water-containing mixed solvent, and recrystallizing the crude product with methanol to obtain 540kg of high-purity white crystal 4, 4' -dihydroxybiphenyl with the purity of 99.7% and the yield of 90%; freezing and recovering isobutene generated in the reaction.
Example 4:
this example is a process for the synthesis of 4, 4' -dihydroxybiphenyl using a loop reactor, comprising the steps of:
firstly, adding 600kg of phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding 6kg of aluminum chloride and 7kg of phenyl aluminum, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 90-110 ℃, and reacting for 4 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 4500kg of octanol, adding 10kg of sodium methoxide, continuously introducing oxygen, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 70-90 ℃, reacting for 2.5 hours, then introducing nitrogen to exhaust oxygen, heating to 185-200 ℃, reacting for 4 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl diphenol;
fourthly, dissolving the tetra-tert-butyl biphenyl diphenol in the water-containing mixed solvent recovered in the third embodiment, and distilling off water at the temperature of 120 ℃; then slowly adding a mixture of 26kg of benzenesulfonic acid and 26kg of p-toluenesulfonic acid, controlling the temperature to be 140-160 ℃, reacting for 4 hours, cooling to room temperature, adding 100kg of water, carrying out centrifugal filtration to obtain a crude product, recovering a mixed solvent, recrystallizing the crude product by using methanol to obtain 540kg of high-purity white crystal 4, 4' -dihydroxybiphenyl, wherein the purity is 99.6%, and the yield is 89.3%; freezing and recovering isobutene generated in the reaction.
Example 5:
the present embodiment is different from the third embodiment in that: and step four, sublimating the crude product by using a sublimation device, controlling the temperature to be 220-320 ℃, and sublimating to obtain 510kg of high-purity white crystal 4, 4' -dihydroxybiphenyl, wherein the purity is 99.8 percent, and the total yield is 85.9 percent.
Example 6:
this example is a process for the synthesis of 4, 4' -dihydroxybiphenyl using a loop reactor, comprising the steps of:
firstly, adding 500kg of phenol into a reaction kettle provided with a loop reaction system;
secondly, introducing nitrogen for evacuation, adding 5kg of zinc chloride and 6kg of phenyl aluminum, introducing isobutene, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 90-110 ℃, and reacting for 4 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 200kg of p-methylphenol, adding 33kg of potassium hydroxide, continuously introducing air, reacting by using a reaction kettle provided with a loop reaction system, controlling the temperature to be 70-90 ℃, reacting for 4 hours, introducing nitrogen to exhaust oxygen, heating to 185-200 ℃, reacting for 5 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl diphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent of benzene and decane, wherein the mass ratio of the benzene to the decane in the mixed solvent is 1: 5; then slowly adding a mixture of 32kg of chlorosulfonic acid and 32kg of p-toluenesulfonic acid, controlling the temperature to be 135-160 ℃, reacting for 6.5h, cooling to room temperature, adding 80kg of water, carrying out centrifugal filtration to obtain a crude product, recovering a water-containing mixed solvent, and recrystallizing the crude product with ethyl acetate to obtain 440kg of high-purity white crystal 4, 4' -dihydroxybiphenyl with the purity of 99.5% and the yield of 88.9%; freezing and recovering isobutene generated in the reaction.
Control experiment
Firstly, adding 800kg of phenol into a common reaction kettle;
secondly, introducing nitrogen for evacuation, adding 2kg of isopropyl aluminum, introducing isobutene, controlling the temperature to be 90-110 ℃, and reacting for 9 hours to obtain di-tert-butylphenol;
dissolving di-tert-butylphenol in 4500kg of amyl alcohol, adding 85kg of potassium carbonate, continuously introducing oxygen, controlling the temperature to be 70-80 ℃, reacting for 3.5 hours, then introducing nitrogen to exhaust oxygen, heating to 185-200 ℃, reacting for 6 hours, cooling to room temperature, and filtering to obtain tetra-tert-butyl biphenyl diphenol;
dissolving tetra-tert-butyl biphenyl diphenol in a mixed solvent of toluene and undecane, wherein the mass ratio of toluene to undecane in the mixed solvent is 1: 5; slowly adding 17kg of methanesulfonic acid, controlling the temperature to be 130-160 ℃, reacting for 9 hours, cooling to room temperature, performing centrifugal filtration to obtain a crude product, recovering the mixed solvent, recrystallizing the crude product by using ethyl acetate to obtain 630kg of high-purity white crystal 4, 4' -dihydroxybiphenyl, wherein the purity is 98.9%, and the yield is 79.6%; freezing and recovering isobutene generated in the reaction.
In the second and third steps of the experiment, the reaction is carried out by only starting stirring under the condition of not starting a circulating pump, and the rotating speed is controlled to be 30-60 r/min.