A method for preparing 4,4'-dihydroxybiphenyl compound

Abstract

A method for preparing a 4,4'-dihydroxybiphenyl compound relates to a method for preparing an organic compound. The method uses 2,6-di-tert-butylphenol as a raw material and a new copper complex as a catalyst to efficiently generate 3,3',5,5'-tetra-tert-butylbiphenyl, which is de-tert-butylated to generate 4,4'-dihydroxybiphenyl. 4,4'-dihydroxybiphenyl is an important organic intermediate, often used as a rubber antioxidant and plastic antioxidant, for colorless vulcanized rubber products, rubber products for food packaging and medical latex products, and also for sulfur chloride cold vulcanized products, such as medical gloves. At the same time, it is also a dye intermediate and a stabilizer for petroleum products, such as a stabilizer for synthetic photosensitive materials and lubricating greases. In terms of synthetic polymers, due to its excellent heat resistance, it is often used as a modified monomer for polyesters, polyurethanes, polycarbonates, polysulfones and epoxy resins, etc., to manufacture excellent engineering plastics and composite materials.

Description

Technical Field

[0001] The invention relates to a method for preparing an organic compound, in particular to a method for preparing a 4,4'-dihydroxybiphenyl compound. Background Art

[0002] In recent years, rubber has been widely used in daily life, medical and health industry, transportation, industry, agriculture, scientific experiments, national defense, aerospace and other fields due to its excellent wear resistance, heat resistance, acid and alkali resistance, plasticity and other characteristics. However, as rubber continues to age during use, its performance will gradually weaken, so it is necessary to add some antioxidants to the rubber to slow down its aging and extend the service life of rubber and its products, such as adding 4,4'-dihydroxybiphenyl. Because of its odorless, tasteless and non-toxic characteristics, it is widely used in light-colored vulcanized products, food packaging glue, medical latex products and other aspects. In addition, due to its high heat resistance, 4,4'-dihydroxybiphenyl can be used as a modified monomer of polyester or resin to manufacture excellent composite materials and engineering plastics. Liquid crystal polymers synthesized from 4,4'-dihydroxybiphenyl and its derivatives can also be spun to make high-strength fibers, such as optical fiber reinforcement materials, composite materials and ropes. At the same time, 4,4'-dihydroxybiphenyl can also be used as dye intermediates, synthetic photosensitive materials, stabilizers for petroleum products (such as stabilizers for lubricating greases), plastic antioxidants, etc.

[0003] 4,4'-Dihydroxybiphenyl and its derivatives are an important class of compounds. They are widely present in biologically active molecules and are a class of valuable intermediates in the chemical and pharmaceutical industries. The main disadvantages of the traditional method of synthesizing 4,4'-dihydroxybiphenyl include strict reaction conditions, poor compatibility with functionalized functional groups, and a small range of substrate applicability. In this context, a large number of scientific experiments are devoted to studying various effective methods for synthesizing 4,4'-dihydroxybiphenyl. For example, Tong Zhibiao, Geng Bin, etc. successively used the method of sulfonation followed by hydrolysis to prepare 4,4'-dihydroxybiphenyl. This process has the advantages of simple synthesis route and high yield, so it is widely used in industrial production, but a large amount of concentrated acid and strong base are consumed during the reaction process, causing great environmental pollution. John H. Golbeck et al. used fungi to catalyze biphenyl to synthesize 4,4'-dihydroxybiphenyl in one step. Although the reaction steps are reduced, specific fungi need to be cultured in advance. This process is time-consuming and has high requirements for the culture environment. In addition, the fungi used in the experiment have poor selectivity and are easy to catalyze the production of multiple hydroxybiphenyls, and the yield of the target product is low. Therefore, this method is limited to laboratory synthesis and is difficult to promote industrialization. Alessandro Prastaro et al. used scarce and expensive palladium complexes as catalysts, and para-hydroxyphenylboronic acid and para-halogenated phenol as substrates to produce 4,4'-dihydroxybiphenyl by self-coupling or cross-coupling. Although metal catalysts have the characteristics of accelerating chemical reactions without participating in the final changes themselves, they will still be inactivated after repeated use. In view of the scarce resources and high prices of catalysts for such reactions, such synthesis methods are not suitable for large-scale industrial production. Takahashi Katsunori et al. studied the oxidative coupling of alkylphenols in the presence of oxidants such as oxygen or hydrogen peroxide, and then obtained biphenyl derivatives by dealkylation. However, due to the complex process and many reaction steps of such methods, the final yield of the target product is directly affected. GW Gray et al. used this reaction mechanism to diazotize and hydrolyze benzidine to obtain 4,4'-dihydroxybiphenyl. However, due to the instability of diazonium salts, the reaction needs to be carried out at low temperature (below 5°C), and both benzidine and sodium nitrite are highly toxic, and diazonium salts are easy to decompose and explode, which is not conducive to its promotion in industrial production. In foreign countries, 4,4'-dihydroxybiphenyl is mainly prepared by three steps of oxidative coupling, reduction and dealkylation of 2,6-di-tert-butylphenol, and the reaction operation process is complicated and energy-intensive.

[0004] At present, its high-purity products are mainly used for the synthesis of liquid crystal polymers. 4,4'-dihydroxybiphenyl is widely used, but due to the limitations of technology, production, process, environmental protection and other aspects, the current domestic production capacity of high-purity 4,4'-dihydroxybiphenyl has been very low and in short supply. Summary of the invention

[0005] The object of the present invention is to provide an efficient method for preparing a 4,4'-dihydroxybiphenyl compound. The present invention uses a copper catalyst to prepare the above compound, and the reaction is carried out under normal pressure air. The present invention uses 2,6-di-tert-butylphenol as a raw material, and a copper complex as a catalyst to efficiently generate 3,3',5,5'-tetra-tert-butylbiphenol, and then de-tert-butylates to generate 4,4'-dihydroxybiphenyl. The two-step method efficiently prepares 4,4'-dihydroxybiphenyl, and has good industrial application prospects.

[0006] The technical solution adopted by the present invention is:

[0007] A method for preparing a 4,4'-dihydroxybiphenyl compound comprises the following steps: using 2,6-di-tert-butylphenol as a raw material, using a cuprous chloride / tetramethylguanidine complex as a catalyst, and air as an oxidant to synthesize 3,3',5,5'-tetra-tert-butylbiphenol by oxidative coupling, and adding p-toluenesulfonic acid to 3,3',5,5'-tetra-tert-butylbiphenol to perform de-tert-butylation to generate 4,4'-dihydroxybiphenyl. The reaction route is as follows:

[0008]

[0009] The above-mentioned method for preparing a 4,4'-dihydroxybiphenyl compound, wherein the copper complex is a cuprous chloride / tetramethylguanidine complex

[0010] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the copper complex catalyst is cuprous chloride / tetramethylguanidine in a molar ratio of 1:1.

[0011] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the oxidant is air.

[0012] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the reaction temperature is 150°C-210°C, and the preferred reaction temperature is 180°C.

[0013] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the reaction solvent is propylene carbonate, N,N-dimethylaniline, N-methylpyrrolidone and 2-cyanopyridine, and the preferred reaction solvent is 2-cyanopyridine.

[0014] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the amount of the catalyst is 1-10 wt%, preferably 1 wt%.

[0015] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the gas flow rate is 0.1-1 mL / min, and the preferred gas flow rate is 0.1 mL / min.

[0016] In the above-mentioned method for preparing a 4,4'-dihydroxybiphenyl compound, the reaction time is 5-15 h, and the preferred reaction time is 8 h.

[0017] In the above-mentioned method for preparing a 4,4'-dihydroxybiphenyl compound, the product recrystallization solvent is ethanol.

[0018] In the above-mentioned method for preparing 4,4'-dihydroxybiphenyl compounds, the second-step catalyst is p-toluenesulfonic acid.

[0019] The above-mentioned method for preparing a 4,4'-dihydroxybiphenyl compound is characterized in that the reaction pressure is at normal pressure.

[0020] The beneficial effects of the present invention are:

[0021] The invention uses cuprous chloride / tetramethylguanidine as a catalyst, has good innovation and high reaction efficiency.

[0022] The invention uses cuprous chloride / tetramethylguanidine catalyst for the reaction of synthesizing 4,4'-dihydroxybiphenyl compound, and the catalyst has high activity, good stability and high economy.

[0023] The method of the invention is used to synthesize 4,4'-dihydroxybiphenyl compounds, with fewer reaction steps and lower energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a comparative state diagram of 4,4'-dihydroxybiphenyl of the present invention. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below by way of examples, but the examples are not intended to limit the present invention.

[0026] Example 1 Synthesis of 4,4'-dihydroxybiphenyl

[0027] The structural formula of 4,4'-dihydroxybiphenyl is shown below:

[0028]

[0029] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 180°C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 99%. 3,3',5,5'-tetra-tert-butylbiphenol was dealkylated under the catalysis of p-toluenesulfonic acid to obtain an off-white solid, which was recrystallized from ethanol solvent to obtain a white solid 4,4'-dihydroxybiphenyl.

[0030] 1 H NMR data ( Figure 1 ): 1 H NMR (CDCl 3 , 500 MHz) δ (ppm): 9.35 (s, 2 H), 7.37 (d, J = 8.8 Hz, 4H), 6.79 (d, J = 8.4 Hz, 4H).

[0031] Comparative Example 1 Synthesis of 4,4'-dihydroxybiphenyl

[0032] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, and 0.1 g of cuprous chloride were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 180°C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 45%.

[0033] Comparative Example 2 Synthesis of 4,4'-dihydroxybiphenyl

[0034] 10 g of 2,6-di-tert-butylphenol and 50 mL of 2-cyanopyridine were added to a 100 mL round-bottom flask, followed by air, heating and stirring. The reaction temperature was controlled at 180°C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. No 3,3',5,5'-tetra-tert-butylbiphenol compound was obtained.

[0035] Comparative Example 3 Synthesis of 4,4'-dihydroxybiphenyl

[0036] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by oxygen, heating and stirring. The reaction temperature was controlled at 180 °C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 72%.

[0037] Comparative Example 3 Synthesis of 4,4'-dihydroxybiphenyl

[0038] 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added to a 100 mL round-bottom flask, followed by nitrogen gas, heating and stirring. The reaction temperature was controlled at 180 °C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. No 3,3',5,5'-tetra-tert-butylbiphenol compound was obtained.

[0039] Comparative Example 4 Synthesis of 4,4'-dihydroxybiphenyl

[0040] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 180 °C, the gas flow rate was controlled at 1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 78%.

[0041] Comparative Example 5 Synthesis of 4,4'-dihydroxybiphenyl

[0042] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 150 °C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 62%.

[0043] Comparative Example 6 Synthesis of 4,4'-dihydroxybiphenyl

[0044] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 210°C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 70%.

[0045] Comparative Example 7 Synthesis of 4,4'-dihydroxybiphenyl

[0046] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of propylene carbonate, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 180 °C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, which was 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 64%.

[0047] Comparative Example 8 Synthesis of 4,4'-dihydroxybiphenyl

[0048] In a 100 mL round-bottom flask, 10 g of 2,6-di-tert-butylphenol, 50 mL of N,N-dimethylaniline, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine were added in sequence, followed by air, heating and stirring. The reaction temperature was controlled at 180 °C, the gas flow rate was controlled at 0.1 mL / min, and the reaction was stopped after 8 hours. The solvent was evaporated to obtain a red powdery solid, 3,3',5,5'-tetra-tert-butylbiphenol, with a reaction yield of 48%.

[0049] The above examples show that the method for preparing a 4,4'-dihydroxybiphenyl compound of the present invention uses cuprous chloride / tetramethylguanidine complex as a catalyst, air as an oxidant, and 2,6-di-tert-butylphenol as a starting material to prepare 3,3',5,5'-tetra-tert-butylbiphenol in one step, and 3,3',5,5'-tetra-tert-butylbiphenol is dealkylated under the action of p-toluenesulfonic acid to obtain a 4,4'-dihydroxybiphenyl compound. The three-step synthesis process route for preparing 4,4'-dihydroxybiphenyl by oxidative coupling of 2,6-di-tert-butylphenol, which is currently industrialized abroad, is simplified.

Claims

1. A method for preparing a 4,4'-dihydroxybiphenyl compound, characterized in that: The method comprises the following steps: adding 10 g of 2,6-di-tert-butylphenol, 50 mL of 2-cyanopyridine, 0.1 g of cuprous chloride and 0.17 g of tetramethylguanidine in a 100 mL round-bottom bottle, then introducing air, heating and stirring; controlling the reaction temperature at 180°C, the gas flow rate at 0.1 mL / min, and stopping the reaction after 8 hours of reaction; evaporating the solvent to obtain a red powdery solid, which is 3,3',5,5'-tetra-tert-butylbiphenol, and the reaction yield is 99%; dealkylating 3,3',5,5'-tetra-tert-butylbiphenol under the catalysis of p-toluenesulfonic acid to obtain an off-white solid, and the off-white solid is recrystallized with an ethanol solvent to obtain a white solid 4,4'-dihydroxybiphenyl, wherein the structural formula of the 4,4'-dihydroxybiphenyl is: .

Images