CN112374970A

CN112374970A - Synthesis of biphenols

Info

Publication number: CN112374970A
Application number: CN202011394759.4A
Authority: CN
Inventors: 黄楠楠; 徐永海; 姚林山; 牛立中
Original assignee: Fuyu County Agricultural Technology Extension Center; Heilongjiang University; Heilongjiang University of Chinese Medicine
Current assignee: Fuyu County Agricultural Technology Extension Center; Heilongjiang University; Heilongjiang University of Chinese Medicine
Priority date: 2020-12-02
Filing date: 2020-12-02
Publication date: 2021-02-19
Anticipated expiration: 2040-12-02
Also published as: CN112374970B

Abstract

The invention discloses a green process route of biphenol. Biphenyl is adopted to prepare the diphenylethanone through Friedel-crafts acylation reaction, wherein, the waste water containing aluminum trichloride generated by Friedel-crafts acylation hydrolysis can be processed to obtain polyaluminium chloride, which is widely used for sewage treatment. The obtained acetophenone is subjected to Baeyer-Villiger oxidation rearrangement reaction to obtain the biphenyl acetic ester, an oxidant used in the Baeyer-Villiger oxidation rearrangement reaction is a maleic anhydride/hydrogen peroxide system, and maleic anhydride can be obtained again by a reaction by-product maleic acid through dehydration treatment, so that the reutilization of the oxidant is realized. And finally, hydrolyzing the biphenyl acetic ester with alkaline water to obtain the final product of the diphenol. The synthesis process designed by the invention is a safe, green and environment-friendly process route, has mild reaction and controllable reaction process, and has high industrial value.

Description

Synthesis of biphenols

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a synthesis process of biphenol.

Background

Biphenol is also called p-phenylphenol and has a molecular formula of C₆H₅C₆H₄OH, the structural formula is as follows:

biphenol is a nearly white crystal, insoluble in water, soluble in ethanol, caustic soda solution and various organic solvents. The biphenol is an important novel fine chemical intermediate, and the red light sensitizing dye and the green light sensitizing dye synthesized by the product are one of the main raw materials of a color film and can be used as an analysis reagent; it can also be used for preparing oil soluble resin and emulsifier, and used as corrosion-resistant paint component, printing and dyeing carrier, etc. In summary, biphenol is widely used in the fields of dyes, pesticides, antiseptics, paints, printing and dyeing auxiliaries, photosensitive materials, and the like.

In view of potential application of diphenol, the demand of diphenol in China is increasing year by year, and at present, in the aspect of synthesis, a plurality of defects exist, and as for a typical method of industrial synthesis, for example:

the cyclohexanone phenol method is used for preparing the diphenol. Specifically, phenol and cyclohexanone are first condensed to produce 1, 1-bis- (4-hydroxyphenyl) cyclohexane, which is separated from the reaction system and heated under the action of hydrogen transfer catalyst to produce cracking dehydrogenation reaction, and the excessive phenol in the first step may be used as hydrogen absorbent in the second step. After the reaction is completely finished, the reaction product does not need to be separated and purified, so the method is simpler and better in economy, and has the defects that the activity of the used Pd/C catalyst has great influence on the reaction, the reaction time is longer, and the method is gradually replaced by a biphenyl sulfonation alkali fusion method at present.

The biphenyl sulfonation alkali fusion method for producing the p-phenylphenol has been industrialized for many years abroad, for example, Bayer company in Germany, three photochemical companies in Japan and the like are adopted to produce the p-phenylphenol by the method, and the technology is relatively mature. The method comprises the steps of sulfonating biphenyl by sulfuric acid, diluting a sulfonated mixture by water, partially neutralizing by a sodium hydroxide solution, and then filtering and drying to obtain sodium salt of sulfonic acid; then the sodium sulfonate salt reacts with alkali melt for a long time at high temperature (at least 350 ℃), and the reaction solution is poured into hot water after the reaction. The process is not satisfactory in both purity and yield. The production environment in the operation process is hard and the safety is poor due to the adoption of high temperature and post-treatment in the reaction process. The salts generated in the sulfonation process of biphenyl contain sodium sulfate, sodium sulfite and sodium bisulfite, and the latter two salts have reducibility, which brings great difficulty in the aspect of salt treatment.

For the above reasons, it is highly desirable to provide a safe, environmentally friendly, green process for the synthesis of biphenols.

Disclosure of Invention

In order to overcome the above problems, the present inventors have conducted intensive studies to develop a green process route for biphenol. Biphenyl is adopted to prepare the diphenylethanone through Friedel-crafts acylation reaction, wherein, the waste water containing aluminum trichloride generated by Friedel-crafts acylation hydrolysis can be processed to obtain polyaluminium chloride, which is widely used for sewage treatment. The obtained acetophenone is subjected to Baeyer-Villiger oxidation rearrangement reaction to obtain the biphenyl acetic ester, an oxidant used in the Baeyer-Villiger oxidation rearrangement reaction is a maleic anhydride/hydrogen peroxide system, and maleic anhydride can be obtained again by a reaction by-product maleic acid through dehydration treatment, so that the reutilization of the oxidant is realized. And finally, hydrolyzing the biphenyl acetic ester with alkaline water to obtain the final product of the diphenol. The synthesis process designed by the invention is a safe, green and environment-friendly process route, has mild reaction and controllable reaction process, and has high industrial value.

The invention aims to provide a synthesis process of biphenol, which comprises the following steps:

step 1, preparing the acetophenone biphenyl;

step 2, oxidizing and rearranging the acetophenone to obtain biphenyl acetate;

and 3, performing hydrolysis reaction on the biphenyl acetic ester to obtain the biphenol.

Wherein, step 1 includes the following steps:

step 1-1, adding biphenyl, acetyl chloride, a catalyst and an organic solvent into a reactor for reaction;

and 1-2, after the reaction is finished, carrying out post-treatment to obtain the acetophenone biphenyl.

Wherein, in the step 1-1,

the organic solvent is used as an inert solvent, preferably an aprotic organic solvent, and more preferably dichloroethane;

the catalyst is preferably any one or more of ferric oxide, potassium bromide, aluminum trichloride and ferric trichloride, and more preferably aluminum trichloride.

Wherein, in step 1-2, the post-processing comprises: stirring, standing, separating and washing.

Wherein, step 2 includes:

step 2-1, adding the diphenoxyethyl ketone, the oxidant and the organic solvent into a reactor for reaction;

step 2-2, after the reaction is finished, carrying out post-treatment to obtain biphenyl acetic ester;

optionally, subjecting the biphenyl acetic acid ester obtained in the step 2-2 to secondary oxidation rearrangement.

Wherein, in the step 2-1,

the organic solvent is an aprotic organic solvent, and is more preferably the same as the organic solvent used for synthesizing the acetophenone biphenyl.

The oxidizing agent comprises acid anhydride, peracid, inorganic strong acid and peroxide, preferably acid anhydride and hydrogen peroxide as an oxidation reaction system, and more preferably maleic anhydride and hydrogen peroxide.

Wherein, in step 2-2, the post-processing comprises: filtering, standing and separating.

Wherein, step 3 comprises the following steps:

step 3-1, feeding materials into a reactor for reaction;

step 3-2, acidifying the solution obtained in the step 3-1, and adjusting the pH value;

and 3-3, carrying out post-treatment to obtain the diphenol.

Wherein, in step 3-1, the material charged in the reactor comprises a biphenylacetic acid ester, a hydrocarbon derivative, a base and a solvent.

Another aspect of the present invention is to provide a biphenol prepared according to the synthesis process of the first aspect of the present invention.

The invention has the advantages that:

1. when the invention synthesizes diphenol, biphenyl is adopted at the front end to prepare the diphenoyl-ethanone through Friedel-crafts acylation reaction, wherein, aluminum trichloride generated by Friedel-crafts acylation hydrolysis can be processed to obtain polyaluminium chloride, which is widely used for sewage treatment and reduces the generation of three wastes from the source.

2. In the reaction process, the biphenyl acetic ester is prepared through Baeyer-Villiger oxidation rearrangement reaction, the oxidant used in the oxidation rearrangement reaction is a maleic anhydride/hydrogen peroxide system, and maleic anhydride can be obtained again through dehydration treatment of a by-product of the reaction, so that the reutilization of the oxidant is realized.

3. The catalyst used in the invention can be used for sewage treatment after treatment, and the generation of waste water and waste residue is reduced.

4. The invention has simple post-treatment process after the reaction is finished when the diphenol is synthesized, thereby fundamentally solving the problems of more three wastes and serious environmental pollution in the traditional process.

5. The method for synthesizing the diphenol is simple, mild in condition, easy to control and safe in intermediate reaction process, and has high industrial value.

Drawings

FIG. 1 shows the nuclear magnetic hydrogen spectrum of biphenol obtained in example 1 of the present invention.

Detailed Description

The invention is explained in more detail below with reference to the figures and examples. The features and advantages of the present invention will become more apparent from the description.

The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

According to the present invention, a first aspect provides a process for synthesizing a biphenol, the process comprising the steps of:

step 1, preparing the acetophenone.

In a further preferred embodiment, step 1 comprises the steps of:

step 1-1, adding biphenyl, acetyl chloride and an organic solvent into a reactor for reaction.

In step 1-1, the organic solvent serves as an inert solvent to provide a reaction system for the reaction, and preferably the organic solvent is an aprotic organic solvent, such as: dichloromethane, dichloroethane, nitrobenzene, nitromethane, petroleum ether, carbon tetrachloride, etc., more preferably dichloroethane.

In the step 1-1, the inventor researches and discovers that the raw material biphenyl has better solubility in dichloroethane, the dichloroethane is used as a reaction system solvent, the reaction condition and the process are simpler and safer, meanwhile, the reaction process is more stable, and the dichloroethane is used as the reaction system solvent, does not participate in the reaction and is beneficial to the reaction.

In step 1-1, optionally, a catalyst is also added to the reactor. The catalyst is preferably any one or more of ferric oxide, potassium bromide, aluminum trichloride and ferric trichloride, and more preferably aluminum trichloride.

In the invention, the aluminum trichloride is preferably used as a reaction catalyst, so that the reaction process can be accelerated, the acetophenone required by the reaction is conveniently recovered, and the polyaluminum chloride can be obtained by further treatment and used for sewage treatment, the generation of three wastes is reduced from the source, and the method is very environment-friendly.

In a further preferred embodiment, the catalyst is added in batches, and a great deal of practice proves that the disadvantage of uncontrollable reaction due to too fast reaction caused by adding the catalyst in batches can be effectively avoided, the temperature change of the system is small, and the generation of byproducts is properly reduced.

In a further preferred embodiment, the catalyst is added under ice bath conditions at a temperature of less than 18 ℃, preferably less than 12 ℃, more preferably between 0 and 10 ℃, sufficient to ensure that the reaction proceeds such that the reaction is milder and the production of by-products is further reduced.

In step 1-1, the molar ratio of biphenyl to acetyl chloride to catalyst is 0.5-2:0.5-3:0.1-2, preferably 0.8-1.5:0.8-2:0.5-1.5, more preferably 1:1:1.05, wherein the molar amount of biphenyl is based on the molar amount of its molecules, the molar amount of acetyl chloride is based on the molar amount of its molecules, and the molar amount of catalyst is based on the molar amount of its molecules.

In the invention, with the increase of the addition amount of the catalyst, the reaction rate is effectively accelerated, and the selectivity of the acetophenone biphenyl is improved, but the reaction is not greatly influenced by the excessive catalyst, and the workload of the post-treatment is increased.

In step 1-1, the catalyst is added completely, the reaction is preferably continued at room temperature, the reaction time is less than 3 hours, preferably less than 2 hours, and more preferably 30 minutes, the reaction process is simple, the time is short, and the product is easy to obtain.

In step 1-1, the reactor is not limited to any vessel in which a reaction can be carried out, and preferably, the reactor is a flask, and more preferably, the reactor is a four-neck flask, so that reactants can be added at any time during the reaction.

In a preferred embodiment, biphenyl is subjected to friedel-crafts acylation to obtain acetophenone, and the reaction occurring in step 1-1 is represented by formula (1):

In step 1-2, the post-processing comprises: stirring, standing, separating and washing.

In the step 1-2, standing and layering, wherein the supernatant contains the catalyst, and the catalyst is further treated and can be recycled; the lower layer liquid is further washed and used for the subsequent reaction for preparing the target product diphenol.

In the step 1, the acetophenone obtained by the reaction contains organic solvents such as dichloroethane and the like, but no further treatment is needed, because the solvents are added in the subsequent reaction, and practical researches prove that the residual liquid obtained in the step 1 is directly used for synthesizing the target product diphenol in the subsequent reaction, the quality of the diphenol is not influenced, the production and quality requirements of the diphenol are completely met, the used catalyst can be recycled, the generation of three wastes is reduced from the source, and the energy consumption is reduced.

And 2, oxidizing and rearranging the acetophenone to obtain the biphenyl acetic ester.

In a further preferred embodiment, step 2 comprises:

and 2-1, adding the diphenoxyethyl ketone, the oxidant and the organic solvent into the reactor for reaction.

In step 2-1, the organic solvent is an aprotic organic solvent, for example: dichloromethane, dichloroethane, nitrobenzene, nitromethane, petroleum ether, carbon tetrachloride and the like, and more preferably the same organic solvent as used for synthesizing the acetophenone biphenyl, so as to avoid introducing other impurities.

In step 2-1, the oxidizing agent includes an acid anhydride, a peracid, a strong inorganic acid, a peroxide, for example: peroxysulfuric acid, peroxyacetic acid, peroxytrifluoroacetic acid, maleic anhydride, hydrogen peroxide and the like, so that the acetophenone is subjected to Baeyer-Villiger oxidation rearrangement, the anhydride and the hydrogen peroxide are preferably used as an oxidation reaction system, and the maleic anhydride and the hydrogen peroxide are more preferably used.

In step 2-1, maleic anhydride and hydrogen peroxide are preferred as the oxidation reaction system. In the reaction process of synthesizing ester, in order to improve the yield of ester, the reaction needs to be moved rightwards, maleic anhydride is used as an oxidant, the reaction is mild, and the maleic anhydride can properly remove water generated in the reaction, so that the reaction balance is broken, the reaction is promoted to move rightwards, and the reaction yield is improved. In the reaction process, maleic acid generated by the reaction of maleic anhydride can be obtained only by dehydration treatment after the reaction is finished, and the maleic anhydride can be directly applied to the reaction process of the next batch, so that zero emission of three wastes is realized, and the method has great significance for industrial industry.

In the step 2-1, hydrogen peroxide is used as an oxidant, so that the generation of unnecessary side reactions in chemical synthesis can be effectively reduced and avoided, the reaction vessel is not corroded, the environmental pollution is little, and when the oxidizing capability of the reaction vessel is consumed, only water is generated, so that the expensive cost of wastewater treatment can be reduced.

In step 2-1, the molar ratio of the oxidizing agent maleic anhydride to hydrogen peroxide is 0.1-2:0.3-3, preferably 0.5-1.2:0.8-2, more preferably 1:1, wherein the molar amount of maleic anhydride is the molar amount of its molecules and the molar amount of hydrogen peroxide is the molar amount of its molecules.

In the present invention, the inventors have studied and found that, when the molar ratio of maleic anhydride to hydrogen peroxide is 0.1 to 2:0.3 to 3, particularly 1:1, the conversion of acetophenone is highest, and excessive maleic anhydride or hydrogen peroxide increases the amount of by-products and is disadvantageous in the post-reaction treatment.

In a further preferred embodiment, the acetophenone, maleic anhydride and organic solvent formed in the reaction of step 1 are added to a reaction vessel, and hydrogen peroxide is added at low temperature. Wherein the cryogenic temperature does not exceed 20 ℃, preferably is below 15 ℃, more preferably is below 10 ℃. Hydrogen peroxide is very easily decomposed, and in order to effectively control the reaction rate, it is preferable to add hydrogen peroxide to the reactor in a dropwise manner at a low temperature.

In step 2-1, preferably after the above-mentioned liquids are mixed uniformly, a catalyst is added thereto and the reaction is continued for 5 to 24 hours, preferably 8 to 16 hours, more preferably 9 to 13 hours, for example 12 hours, the longer the reaction time, the more sufficient the reaction, but the too long reaction time is not of practical significance.

The catalyst is preferably one or more of zinc powder, zinc chloride, ferric chloride and stannous chloride, and more preferably zinc powder.

In the invention, the inventor researches and discovers that the zinc powder is preferably used as a catalyst for the oxidation reaction, so that the reaction process can be effectively accelerated, and more importantly, the reaction is more thorough.

In a further preferred embodiment, the acetophenone undergoes Baeyer-Villiger oxidative rearrangement to give the biphenyl acetate, and the reaction occurring in step 2-1 is as shown in formula (2):

and 2-2, after the reaction is finished, carrying out post-treatment to obtain the biphenyl acetic ester.

In step 2-2, the post-processing comprises: filtering, standing and separating.

In the step 2-2, the filter cake obtained by filtering is collected, processed and recycled; and standing the filtrate to obtain a lower layer solution, namely the reaction solution biphenyl acetic ester required by the subsequent reaction.

In a preferred embodiment, the biphenylacetic acid ester obtained in step 2-2 is subjected to a secondary oxidative rearrangement.

In step 2, the inventors have studied and found that, after the primary oxidation rearrangement reaction is completed, a part of the acetophenone remains unreacted, and in order to improve the conversion of the acetophenone and the selectivity and yield of the phenylacetate, the phenylacetate obtained above is preferably subjected to secondary oxidation.

Further, an oxidant and a catalyst are added into the reaction liquid biphenyl acetic ester, the operation step of the step 2-1 is repeated, and preferably, in order to reduce side reactions and avoid introducing new impurities, the oxidant and the catalyst are selected from the same type as the oxidant and the catalyst used in the step 2-1.

Wherein the oxidant is preferably maleic anhydride and hydrogen peroxide system, the molar weight ratio of maleic anhydride to hydrogen peroxide is 0.1-2:0.3-3, preferably 0.5-1.2:0.8-2, more preferably 1:1, wherein the molar weight of maleic anhydride is the molar weight of its molecules and the molar weight of hydrogen peroxide is the molar weight of its molecules.

Furthermore, after the reaction is finished, the organic solvent and the felbinate are obtained through separation and purification, the felbinate participates in the subsequent reaction process, and the organic solvent is directly used for the next batch of reaction.

In a further preferred embodiment, step 3 comprises the steps of:

and 3-1, adding materials into the reactor to perform reaction.

In step 3-1, the feed to the reactor comprises biphenyl acetate, a hydrocarbon derivative, a base and a solvent.

Among them, the hydrocarbon derivatives are preferably alcohols including methanol, butanol, isopropanol, and ethylene glycol, and more preferably methanol. The methanol is cheap and easy to obtain and recover, and the biphenyl acetic ester has good solubility in the methanol and cannot influence the reaction.

Wherein, the biphenyl acetic ester is hydrolyzed in alkaline environment to generate biphenyl phenolate. The alkali is strong alkali, including potassium hydroxide, sodium hydroxide, lithium hydroxide, sodium carbonate, preferably strong alkali metal hydroxide, more preferably sodium hydroxide.

In the step 3-1, sodium hydroxide is used as an alkali-soluble solvent, so that the biphenyl phenolate with higher quality can be obtained.

Wherein, the solvent is water or deionized water, preferably water, and the source is wide.

In step 3-1, a base and a solvent provide a base-soluble environment for the biphenyl acetate.

In step 3-1, the above-mentioned raw materials are charged into a reactor and reacted under reflux.

And 3-2, acidifying the solution obtained in the step 3-1, and adjusting the pH.

In step 3-2, an acidic solution is selected for acidification, wherein the acidic solution is a strong acid, preferably an inorganic strong acid, and more preferably hydrochloric acid.

In the invention, the inventor researches and discovers that the pH value of the system is adjusted to 3-4 by hydrochloric acid, which is beneficial to improving the quality and yield of the finished product of the diphenol.

In a further preferred embodiment, the biphenyl acetic acid ester is hydrolyzed in an alkali-soluble environment to obtain biphenol salt, and the biphenyl salt is acidified to obtain biphenol, wherein the reaction is represented by the formula (3):

and 3-3, carrying out post-treatment to obtain the diphenol.

In step 3-3, the post-processing comprises: stirring, filtering, washing with water, drying and recrystallizing.

Among them, the solvent used for the recrystallization is preferably an alcohol, such as isopropyl alcohol.

According to the present invention, a second aspect provides a diphenol prepared according to the synthesis process of the first aspect of the present invention.

The synthesis process of the diphenol provided by the invention realizes the reutilization of the catalyst and the oxidant, the reaction process does not involve high-temperature reaction, and compared with the prior large-scale preparation of the diphenol by the biphenyl sulfonation alkali fusion method, the synthesis process of the diphenol has the advantages of less pollution, mild reaction, controllable reaction process and simple equipment, and has very high industrial value.

Examples

Example 1

150ml of dichloroethane, 30.8g of biphenyl and 15.7g of acetyl chloride are added into a 500ml four-mouth bottle, 28.8g of aluminum trichloride is added in batches under the cooling of an ice bath, and the temperature is controlled between 0 and 10 ℃. After the addition, the stirring is continued for 0.5 hour, the ice bath is removed, the temperature is naturally raised to the room temperature, the stirring is continued for 0.5 hour, and the liquid phase monitoring is carried out. After the reaction is finished, pouring the obtained solution into 150ml of ice water, stirring for 20min, and standing for layering. The lower layer was washed with water, the organic layer was distilled off to about 1/3, and the remaining residue was used directly in the next reaction.

Adding the solution after the reaction treatment in the previous step, 40g of maleic anhydride and 100ml of dichloroethane into a 500ml four-mouth bottle, cooling to below 10 ℃, dropwise adding 27.2g of 50% hydrogen peroxide, controlling the temperature to be between 0 and 10 ℃, continuously stirring for 2.0h after the addition is finished, and adding 0.5g of zinc powder. Stirring for 12.0 hours at room temperature, detecting the product content by a liquid phase to be about 85%, filtering the obtained solution, standing the filtrate, removing a water layer to obtain a reaction liquid of the next reaction, refluxing and dewatering filter cake maleic acid by dimethylbenzene to obtain maleic anhydride, directly using the maleic anhydride in the reaction process of secondary oxidation, and directly using the redundant maleic anhydride in the next reaction.

Adding 20g of maleic anhydride obtained by the reaction treatment in the previous step into the obtained reaction liquid, dropwise adding 13.6g of hydrogen peroxide with the concentration of 50% and 0.2g of zinc powder, repeating the first dropwise adding and reaction process, after the reaction is finished, evaporating dichloroethane at normal pressure, and then evaporating the solvent under reduced pressure to obtain a light yellow solid, wherein the evaporated dichloroethane is directly added into the next batch for reaction.

The above pale yellow solid, 100ml of methanol, 24g of sodium hydroxide and 100ml of water were put into a 500ml reaction flask, and reacted under reflux for 1.0 hour, and the reaction was monitored in the liquid phase. After the reaction conversion is finished, cooling to below 20 ℃, dropwise adding 60ml of 35% hydrochloric acid, adjusting the pH value to be between 3 and 4, stirring for 0.5 hour, filtering, washing with water, and drying to obtain about 28.0g of crude diphenol product.

And (3) further carrying out recrystallization treatment on the crude diphenol product: pulping treatment with isopropanol, and filtering and drying white powdery solid diphenol about 25.0 g.

The biphenol obtained was characterized by a nuclear magnetic hydrogen spectrum as shown in FIG. 1, further demonstrating the final product structure obtained.

The invention has been described in detail with reference to the preferred embodiments and illustrative examples. It should be noted, however, that these specific embodiments are only illustrative of the present invention and do not limit the scope of the present invention in any way. Various modifications, equivalent substitutions and alterations can be made to the technical content and embodiments of the present invention without departing from the spirit and scope of the present invention, and these are within the scope of the present invention. The scope of the invention is defined by the appended claims.

Claims

1. A process for synthesizing biphenol, characterized in that said process comprises the following steps:

step 1, preparing the acetophenone biphenyl;

step 2, oxidizing and rearranging the acetophenone to obtain biphenyl acetate;

2. The process according to claim 1, wherein step 1 comprises the steps of:

3. The process according to claim 2, wherein, in step 1-1,

4. A process according to claim 2 or 3, characterized in that in step 1-2, the post-treatment comprises: stirring, standing, separating and washing.

5. The process of claim 1, wherein step 2 comprises:

6. The process according to claim 5, characterized in that in step 2-1, the organic solvent is an aprotic organic solvent, more preferably the same organic solvent as used for the synthesis of diphenophenone;

7. The process according to claim 5 or 6, characterized in that in step 2-2, the post-treatment comprises: filtering, standing and separating.

8. The process according to claim 1, wherein step 3 comprises the steps of:

step 3-1, feeding materials into a reactor for reaction;

and 3-3, carrying out post-treatment to obtain the diphenol.

9. The process of claim 8, wherein in step 3-1, the materials added to the reactor comprise biphenyl acetate, a hydrocarbon derivative, a base, and a solvent.

10. Biphenol produced according to the synthesis process of one of claims 1 to 9.