A method for preparing 1,2-bis(4-vinylphenyl)ethane
Compound 2 is generated by reacting compound 1 with p-toluenesulfonylhydrazine and then undergoing an elimination reaction under alkaline conditions. This solves the problem of low purity and yield of 1,2-bis(4-vinylphenyl)ethane in the prior art, and achieves the preparation of high purity and high yield, which is suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- JINAN DINGHAO PHARM TECH CO LTD
- Filing Date
- 2026-04-15
- Publication Date
- 2026-07-03
Smart Images
Figure CN122010660B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic chemistry, and in particular to a method for preparing 1,2-bis(4-vinylphenyl)ethane. Background Technology
[0002] 1,2-Bis(4-vinylphenyl)ethane, as an important difunctional styrene monomer, is widely used in 3D printing crosslinking resins, electronic packaging materials, high-frequency substrates, photoresist resins, printed circuit board (PCB) laminates, and other fields. It has good mechanical properties, heat resistance, low dielectric constant and low dielectric loss.
[0003] In the prior art, the synthesis methods include the following:
[0004] (1) Wittig reaction method: Chinese invention patent CN120794805A discloses a method for synthesizing 1,2-bis(4-vinylphenyl)ethane, which uses 1,2-bis(p-formaldehyde phenyl)ethane as a raw material and reacts it with methyltriphenylphosphine halide under strong alkaline conditions to prepare 1,2-bis(4-vinylphenyl)ethane. However, this method has high raw material costs, complex post-reaction processing, and may produce isomer impurities.
[0005] (2) Metal Coupling Method: Chinese invention patent CN119263950A discloses a method for synthesizing 1,2-bis(4-vinylphenyl)ethane. Using p-halobenzyl halide as a raw material, 1,2-bis(4-halophenyl)ethane is obtained through a self-coupling reaction catalyzed by magnesium or zinc. This 1,2-bis(4-vinylphenyl)ethane is then coupled with a vinyl Grignard reagent or vinyl chloride to prepare 1,2-bis(4-vinylphenyl)ethane. However, this method has high raw material costs, uses highly toxic vinyl chloride and easily explosive metals, posing safety hazards. Furthermore, the reaction conditions are strict and the operation is complex.
[0006] (3) Acid-catalyzed dehydration method: Chinese invention patent CN113372187A discloses an industrial synthesis method for BVPE, which involves reducing compound 1 and then reacting it with p-toluenesulfonic acid as a catalyst. Chinese invention patent CN115385767A discloses a method for preparing divinyl aromatic compounds, which involves reducing compound 1 and then reacting it with p-toluenesulfonic acid pyridinium salt as a catalyst. The above methods have simple preparation processes, but require strict control of the concentration of the acid catalyst and the reaction time. Since the product is prone to polymerization under acidic conditions, it is difficult to obtain high-purity monomers, resulting in low yields, which are not suitable for industrialization.
[0007] Therefore, there is an urgent need to develop a new method for preparing 1,2-bis(4-vinylphenyl)ethane. Summary of the Invention
[0008] To address the aforementioned technical problems, this invention provides a method for preparing 1,2-bis(4-vinylphenyl)ethane. The method of this invention features mild reaction conditions, simple operation, high product purity, and high yield, making it suitable for industrial production.
[0009] In a first aspect, the present invention provides a method for preparing 1,2-bis(4-vinylphenyl)ethane, wherein the reaction formula is as follows:
[0010]
[0011] The preparation method includes the following steps:
[0012] (1) Compound 1, p-toluenesulfonylhydrazine, and organic solvent 1 were mixed and reacted to obtain compound 2;
[0013] (2) The compound 2 is reacted in organic solvent 2 under the action of alkali and polymerization inhibitor to generate 1,2-bis(4-vinylphenyl)ethane.
[0014] In the above technical solution, step (1) is a hydrazination reaction, in which compound 1 (1,2-bis(4-acetylphenyl)ethane) reacts with p-toluenesulfonylhydrazine under suitable conditions to generate a stable dihydrazone intermediate, namely compound 2. This step realizes the conversion from carbonyl to hydrazone, providing a key precursor for the subsequent elimination reaction, and the reaction conditions are mild, the conversion rate is high, and the intermediate is easy to separate and purify.
[0015] Step (2) is a base-induced elimination reaction. The base acts on the β-methylene group of the hydrazone in compound 2, causing it to lose a proton, thereby initiating an elimination reaction. After two eliminations, two vinyl groups are generated, ultimately yielding 1,2-bis(4-vinylphenyl)ethane.
[0016] Optionally, the equivalent of p-toluenesulfonyl hydrazine is 2-3 eq; preferably, the equivalent of p-toluenesulfonyl hydrazine is 2.4-2.6 eq.
[0017] In the above technical solution, using 2-3 eq equivalents of p-toluenesulfonyl hydrazine ensures complete reaction of both carbonyl groups and avoids raw material residue. Preferably, 2.4-2.6 eq equivalents can reduce the post-processing burden caused by excess reagent while maintaining high conversion rates.
[0018] Optionally, the organic solvent 1 is any one of 1,2-dichloroethane, ethanol, and methanol; preferably, the organic solvent 1 is 1,2-dichloroethane.
[0019] In the above technical solution, the selected organic solvent 1 can effectively dissolve the reactants and promote the homogeneous reaction. Among them, 1,2-dichloroethane, due to its moderate polarity and boiling point, can effectively promote the reaction and maintain the stability of the system at reflux temperature.
[0020] Optionally, the reaction temperature in step (1) is 60-90℃ and the reaction time is 1-4 h.
[0021] In the above technical solution, sufficient reaction kinetics can be provided within the reaction temperature range to accelerate the hydrazination reaction, while avoiding side reactions caused by excessively high temperatures. A reaction time of 1-4 hours ensures complete reaction, and the reaction endpoint can be controlled by HPLC monitoring.
[0022] Optionally, the alkali has an equivalent of 5-7 eq, and the alkali is at least one selected from potassium carbonate, sodium tert-butoxide, sodium methoxide, and sodium hydroxide; preferably, the alkali is sodium tert-butoxide.
[0023] In the above technical solution, under the action of a strong base, the methylene group at the β-position of the hydrazone in compound 2 undergoes deprotonation, initiating an elimination reaction to form a corresponding carbanion. This carbanion promotes the elimination of the hydrazone, generating nitrogen gas and p-toluenesulfinate, and forming a vinyl group, while simultaneously forming a carbon-carbon double bond. The stronger the base, the faster the reaction rate and the higher the conversion rate. Sodium tert-butoxide, with its moderate base and good solubility, can efficiently promote elimination without triggering excessive side reactions, resulting in high yield and purity.
[0024] Optionally, the polymerization inhibitor is 1.5-2% of the mass of compound 2, and the polymerization inhibitor is p-tert-butylcatechol.
[0025] In the above technical solution, the polymerization inhibitor is used to capture any free radicals that may be generated, inhibit the polymerization of vinyl monomers during the reaction or post-processing, and ensure the stability and purity of the product monomer form.
[0026] Optionally, the organic solvent 2 is any one of N,N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; preferably, the organic solvent 2 is N,N-dimethylformamide.
[0027] In the above technical solutions, these polar aprotic solvents can effectively dissolve compound 2 and the base, promote homogeneous reactions, and provide a stable high-temperature reaction environment. Among them, N,N-dimethylformamide has good solubility for the reactants and the most suitable boiling point.
[0028] Optionally, the reaction temperature in step (2) is 80-100℃ and the reaction time is 4-6 h.
[0029] In the above technical solution, the reaction temperature and time range provides good kinetic conditions for the elimination reaction, ensuring that the hydrazone intermediate is completely converted into the target olefin, while avoiding decomposition or side reactions caused by excessively high temperature or time.
[0030] Secondly, the present invention provides a 1,2-bis(4-vinylphenyl)ethane prepared by the above method, wherein the purity of the 1,2-bis(4-vinylphenyl)ethane is ≥92% and the yield is ≥71%.
[0031] In summary, the present invention has at least one of the following beneficial technical effects:
[0032] 1. This invention adopts a new route to prepare 1,2-bis(4-vinylphenyl)ethane by reacting compound 1 with p-toluenesulfonylhydrazine to obtain compound 2 under alkaline conditions, which fundamentally avoids the problem of easy polymerization of products in traditional acid-catalyzed dehydration processes, and makes the reaction more controllable.
[0033] 2. By optimizing the alkaline reaction system, the elimination reaction is efficiently promoted under mild conditions, and the reaction yield and product purity are significantly improved compared with existing acid catalysis technologies.
[0034] 3. The 1,2-bis(4-vinylphenyl)ethane monomer prepared by the above method has high purity and few polymerization impurities. When used as a crosslinking agent in photoresists, high-frequency resins and other fields, it can impart better dielectric properties and thermal stability to the materials.
[0035] 4. The method of the present invention is simple to operate, the raw materials are readily available, there is no need to use highly toxic substances or easily explosive reagents, the reaction conditions are mild, there is little waste, the production safety is high, and it is suitable for large-scale industrial production. Attached Figure Description
[0036] Figure 1 The image shows the HPLC spectrum of 1,2-bis(4-vinylphenyl)ethane synthesized in Example 4. Detailed Implementation
[0037] The present invention will be further described in detail below with reference to the embodiments.
[0038] All materials used in the following examples are commercially available. p-Toluenesulfonylhydrazine was purchased from Shanghai Dibo Biotechnology Co., Ltd., and Compound 1 was prepared in-house with a purity >99%.
[0039] This invention provides a method for preparing 1,2-bis(4-vinylphenyl)ethane (compound 3), the reaction formula of which is as follows:
[0040]
[0041] Example 1: This example provides a method for preparing 1,2-bis(4-vinylphenyl)ethane.
[0042] The preparation method includes the following steps:
[0043] S1. At 25°C, 300 mL of ethanol was added to a 1 L three-necked flask, followed by 30 g (0.11 mol, 1.0 eq) of compound 1 and 52 g (0.28 mol, 2.5 eq) of p-methylbenzenesulfonyl hydrazine. The temperature was raised to 88°C and maintained for 1 h. HPLC analysis showed that the reaction was complete. 300 mL of methanol was added to the system and stirred for 0.5 h. The mixture was filtered to obtain 106 g of white wet product, which was dried at 50°C to obtain 65 g of compound 2.
[0044] S2. At 25°C, 1 g (1.66 mmol, 1 eq) of compound 2 and 1.4 g of potassium carbonate (9.9 mmol, 6 eq) were added to 10 mL of N,N-dimethylformamide, followed by 20 mg of p-tert-butylcatechol. The mixture was stirred at 100°C for 6 h, and the reaction was confirmed to be complete by HPLC. The reaction solution was then slowly added to 50 mL of water and extracted twice with 30 mL of 1,2-dichloroethane. The organic phases were combined, concentrated, and then 20 mL of methanol was added. The mixture was stirred for 0.5 h, filtered, and dried at 45°C to obtain 0.29 g of 1,2-bis(4-vinylphenyl)ethane.
[0045] Example 2: This example provides a method for preparing 1,2-bis(4-vinylphenyl)ethane.
[0046] The preparation method includes the following steps:
[0047] S1. At 25°C, 300 mL of methanol was added to a 1 L three-necked flask, followed by 30 g (0.11 mol, 1.0 eq) of compound 1 and 52 g (0.28 mol, 2.5 eq) of p-methylbenzenesulfonyl hydrazine. The temperature was raised to 88°C and maintained for 1 h. HPLC analysis showed that the reaction was complete. 300 mL of methanol was added to the system and stirred for 0.5 h. The mixture was filtered to obtain 106 g of white wet product, which was dried at 50°C to obtain 65 g of compound 2.
[0048] S2. At 25°C, 1 g (1.66 mmol, 1 eq) of compound 2 and 535 mg sodium methoxide (9.9 mmol, 6 eq) were added to 10 mL of dimethyl sulfoxide, followed by 20 mg of p-tert-butylcatechol. The mixture was stirred at 100°C for 6 h. The reaction was confirmed to be complete by HPLC. The reaction solution was slowly added to 50 mL of water and extracted twice with 30 mL of 1,2-dichloroethane. The organic phases were combined, concentrated, and then 20 mL of methanol was added. The mixture was stirred for 0.5 h, filtered, and dried at 45°C to obtain 0.31 g of 1,2-bis(4-vinylphenyl)ethane.
[0049] Example 3: This example provides a method for preparing 1,2-bis(4-vinylphenyl)ethane.
[0050] The preparation method includes the following steps:
[0051] S1. At 25°C, 300 mL of 1,2-dichloroethane was added to a 1 L three-necked flask, followed by the addition of 30 g (0.11 mol, 1.0 eq) of compound 1 and 52 g (0.28 mol, 2.5 eq) of p-methylbenzenesulfonyl hydrazine. The temperature was raised to 88°C and maintained for 1 h. HPLC analysis showed that the reaction was complete. 300 mL of methanol was added to the system and stirred for 0.5 h. The mixture was filtered to obtain 106 g of white wet product, which was dried at 50°C to obtain 65 g of compound 2.
[0052] S2. At 25°C, 1 g (1.66 mmol, 1 eq) of compound 2 and 396 mg of sodium hydroxide (9.9 mmol, 6 eq) were added to 10 mL of dimethylacetamide, followed by 20 mg of p-tert-butylcatechol. The mixture was stirred at 100°C for 6 h. The reaction was confirmed to be complete by HPLC. The reaction solution was slowly added to 50 mL of water and extracted twice with 30 mL of 1,2-dichloroethane. The organic phases were combined, concentrated, and then 20 mL of methanol was added. The mixture was stirred for 0.5 h, filtered, and dried at 45°C to obtain 0.28 g of 1,2-bis(4-vinylphenyl)ethane.
[0053] Example 4: This example provides a method for preparing 1,2-bis(4-vinylphenyl)ethane.
[0054] The preparation method includes the following steps:
[0055] S1. At 25°C, 300 mL of 1,2-dichloroethane was added to a 1 L three-necked flask, followed by the addition of 30 g (0.11 mol, 1.0 eq) of compound 1 and 52 g (0.28 mol, 2.5 eq) of p-methylbenzenesulfonyl hydrazine. The temperature was raised to 88°C and maintained for 1 h. HPLC analysis showed that the reaction was complete. 300 mL of methanol was added to the system and stirred for 0.5 h. The mixture was filtered to obtain 106 g of white wet product, which was dried at 50°C to obtain 65 g of compound 2.
[0056] S2. At 25°C, 1 g (1.66 mmol, 1 eq) of compound 2 and 951 mg of sodium tert-butoxide (9.9 mmol, 6 eq) were added to 10 mL of dimethylacetamide, followed by 20 mg of p-tert-butylcatechol. The mixture was stirred at 100°C for 6 h. The reaction was confirmed to be complete by HPLC. The reaction solution was slowly added to 50 mL of water and extracted twice with 30 mL of 1,2-dichloroethane. The organic phases were combined, concentrated, and then 20 mL of methanol was added. The mixture was stirred for 0.5 h, filtered, and dried at 45°C to obtain 0.32 g of 1,2-bis(4-vinylphenyl)ethane.
[0057] Comparative Example 1: This comparative example provides a method for preparing comparative 1,2-bis(4-vinylphenyl)ethane.
[0058] The preparation steps are as follows:
[0059] 1 g (3.7 mmol, 1.0 eq) of compound 2A was dissolved in 10 mL of xylene, 20 mg of p-tert-butylcatechol was added, followed by 32 mg of p-toluenesulfonic acid (0.05 eq). Under nitrogen protection, the mixture was heated to 140 °C and reacted for 2 h. The reaction mixture was then cooled to 20 °C, filtered, and the xylene was concentrated. The residue was crystallized from 10 mL of methanol, filtered, and dried at 45 °C to give 0.49 g of 1,2-bis(4-vinylphenyl)ethane.
[0060] The properties of 1,2-bis(4-vinylphenyl)ethane obtained by the preparation methods of Examples 1-4 above and the comparative 1,2-bis(4-vinylphenyl)ethane obtained by the preparation method of Comparative Example 1 are shown in Table 1.
[0061] Table 1
[0062]
[0063] Note:
[0064] 1. Yield Calculation: The total yield is calculated based on the initial feed amount of compound 1.
[0065] 2. Purity determination: The purity was determined by high performance liquid chromatography (HPLC) with area normalization method.
[0066] 3. Appearance differences: The products of all embodiments of the present invention are white regular crystals, while the product of Comparative Example 1 is yellowish in color and viscous in its initial state, indicating that it contains more polymeric impurities.
[0067] As shown in Table 1, the alkaline elimination routes provided in Examples 1-4 of this invention significantly outperform traditional acid-catalyzed dehydration routes in terms of yield (71-84%) and purity (92.8-99.3%) of 1,2-bis(4-vinylphenyl)ethane. For example, Comparative Example 1 showed a yield of 56% and a purity of 88.1%. Example 4, using sodium tert-butoxide as the base, demonstrated the best performance, achieving a high yield of 84% and a high purity of 99.3%. Figure 1 The HPLC chromatogram shows a sharp, symmetrical main peak at a retention time of 18.156 minutes, with no other obvious impurity peaks. The purity, calculated using the area normalization method, is greater than 99%, fully demonstrating that the method of this invention can effectively suppress side reactions and obtain extremely high-purity target products. This represents a significant technological advancement in solving product polymerization and improving product quality.
[0068] Furthermore, the products of the embodiments of the present invention are all easily processed solid crystals, while the products of the comparative examples have problems of viscosity and dark color, which further confirms that alkaline conditions can effectively suppress polymerization side reactions from the source, and are more conducive to product separation and purification in industrial production.
[0069] The above examples and data fully demonstrate that the method provided by the present invention has outstanding advantages such as mild reaction conditions, simple operation, high product purity, and high yield. It successfully overcomes the inherent defects of existing acid catalysis technology routes and provides a new and better technical solution for the industrial production of 1,2-bis(4-vinylphenyl)ethane.
[0070] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. A process for the preparation of 1,2-bis(4-vinylphenyl)ethane, characterized in that, The reaction formula is as follows: , The method steps are as follows: (1) Compound 1 and p-toluenesulfonylhydrazine were mixed in an organic solvent to obtain compound 2; (2) The compound 2 is reacted in an organic solvent under the action of an alkali and a polymerization inhibitor to generate 1,2-bis(4-vinylphenyl)ethane; The alkali has an equivalent of 5-7 eq, and the alkali is at least one of potassium carbonate, sodium tert-butoxide, sodium methoxide, and sodium hydroxide; the polymerization inhibitor has a mass of 1.5-2% of the mass of compound 2, and the polymerization inhibitor is p-tert-butylcatechol.
2. The method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 1, characterized in that, The equivalent of p-toluenesulfonyl hydrazine is 2-3 eq.
3. The method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 2, characterized in that, The equivalent of p-toluenesulfonyl hydrazine is 2.4-2.6 eq.
4. The method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 1, characterized in that, The organic solvent in step (1) is any one of 1,2-dichloroethane, ethanol, and methanol.
5. A method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 1, characterized in that, The reaction temperature in step (1) is 60-90℃ and the reaction time is 1-4 h.
6. The method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 1, characterized in that, The organic solvent in step (2) is any one of N,N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide.
7. The method for preparing 1,2-bis(4-vinylphenyl)ethane according to claim 1, characterized in that, The reaction temperature in step (2) is 80-100℃ and the reaction time is 4-6 h.