Method for producing divinyl-substituted aromatic compounds

Abstract

To provide a method for producing a divinyl-substituted aromatic compound safely and inexpensively, with a short induction period, using Grignard reaction.SOLUTION: The present invention provides a method for producing a divinyl-substituted aromatic compound represented by the formula (4), using a product of formula (3), resulting from the reaction between the metal Mg and a vinyl-substituted aromatic halide in the presence of a compound of formula (1): R1-Mg-X1.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 This disclosure relates to a method for producing divinyl-substituted aromatic compounds using the Grinia reaction. [Background technology] 【0002】 Non-patent document 1 describes that when vinyl benzyl chloride is added dropwise to a tetrahydrofuran solution containing metallic magnesium, a Grignier reagent is produced, and bis(vinylphenyl)ethane is obtained by a homocoupling reaction of the produced Grignier reagent. 【0003】 However, it is known that the reaction to produce the Grignier reagent from metallic magnesium does not proceed in the presence of water in the system. Furthermore, because metallic magnesium is covered with a passivation film, it is known that time (induction period) is required for the metallic magnesium to be activated and for the reaction to produce the Grignier reagent to begin. Moreover, once the reaction starts, it can proceed rapidly and generate a large amount of heat, which is dangerous and has been a problem. 【0004】 Methods for shortening the aforementioned induction period include pulverizing metallic magnesium under a nitrogen atmosphere and adding iodine, methyl iodide, ethyl bromide, 1,2-dibromoethane, etc. However, these methods were unsuitable for industrialization due to their high cost and low reproducibility. [Prior art documents] [Non-patent literature] 【0005】 [Non-Patent Document 1] W.-H.Li,et al. Journal of Polymer Science: Part A: Polymer Chemistry, Vol.32, 2023-2027(1994) [Overview of the Initiative] [Problems that the invention aims to solve] 【0006】 Therefore, an object of the present disclosure is to provide a method for producing a divinyl-substituted aromatic compound safely and at low cost with a short induction period using a Grignard reaction. 【Means for Solving the Problems】 【0007】 As a result of intensive studies to solve the above problems, the inventors of the present invention have found that when an aliphatic Grignard reagent is added to a system in which metallic magnesium is reacted with a vinyl-substituted aromatic halide, the induction period is shortened and a vinyl-substituted aromatic Grignard reagent can be obtained promptly, and that when a vinyl-substituted aromatic halide is reacted with the obtained vinyl-substituted aromatic Grignard reagent, a divinyl-substituted aromatic compound can be efficiently obtained. The present disclosure has been completed based on these findings. 【0008】 That is, the present disclosure provides a method for producing a divinyl-substituted aromatic compound including the following steps 1 and 2. Step 1: In the presence of a compound represented by the following formula (1) R 1 -Mg-X 1 (1) (wherein R 1 represents an alkyl group having 1 to 5 carbon atoms, and X 1 represents a halogen atom) react a compound represented by the following formula (2) 【Chemical formula】 (wherein R 2 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and X 2 represents a halogen atom) with metallic magnesium to obtain a compound represented by the following formula (3) 【Chemical formula】 (wherein R 2 , X 2 are the same as defined above). Step 2: React the compound represented by the formula (3) with the following formula (2’)​ [Chemical formula] (In the formula, R 3 represents a single bond or an alkylene group having 1 to 5 carbon atoms, and X 3 represents a halogen atom) React the compound represented by the following formula (4) [Chemical formula] (In the formula, R 2 , R 3 are the same as described above) to obtain a divinyl-substituted aromatic compound represented by the following formula. 【0009】 The present disclosure also provides a method for producing the divinyl-substituted aromatic compound, wherein the reaction in Step 1 is carried out under the condition that 0.01 to 0.20 mol of the compound represented by the formula (1) is present per 1 mol of magnesium metal. 【0010】 The present disclosure also provides a method for producing the divinyl-substituted aromatic compound, wherein the reaction in Step 1 is carried out under a temperature condition of 10 °C or lower. [Advantages of the Invention] 【0011】 In the present disclosure, an aliphatic Grignard reagent such as methylmagnesium chloride is present in the system where magnesium metal reacts with a vinyl-substituted aromatic halide. Then, when water is present in the reaction system, the aliphatic Grignard reagent reacts with water, whereby water can be removed from the system. In addition, the passive film covering the surface of magnesium metal is removed by reacting with the aliphatic Grignard reagent. As a result, magnesium metal is rapidly activated, so that even at a mild temperature, it reacts with a vinyl-substituted aromatic halide to form a vinyl-substituted aromatic Grignard reagent. Therefore, according to the method for producing a divinyl-substituted aromatic compound of the present disclosure, a divinyl-substituted aromatic compound can be rapidly produced by a Grignard reaction under mild conditions. [Embodiments for Carrying Out the Invention] 【0012】 [Method for producing divinyl-substituted aromatic compounds] The method for producing divinyl-substituted aromatic compounds according to this disclosure comprises the following steps 1 and 2. The production method may also include steps other than those described in steps 1 and 2. 【0013】 (Process 1) Step 1 is a step in which a compound represented by formula (1) is reacted with metallic magnesium (Mg) in the presence of a compound represented by formula (2) to obtain a compound represented by formula (3). [ka] 【0014】 In the above formula, R 1 R represents an alkyl group having 1 to 5 carbon atoms. 2 X represents a single bond or an alkylene group having 1 to 5 carbon atoms. 1 , X 2 These represent the same or different halogen atoms. 【0015】 The aforementioned R 1 Examples of C1-C5 alkyl groups in this context include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, and pentyl groups. 【0016】 The aforementioned R 2 Examples of alkylene groups having 1 to 5 carbon atoms include linear or branched alkylene groups such as methylene, methylmethylene, dimethylmethylene, ethylene, propylene, and trimethylene. 【0017】 The aforementioned X 1 , X 2 The halogen atoms in this context include fluorine, chlorine, bromine, and iodine atoms. 【0018】 The compound represented by formula (2) has one vinyl group bonded to the benzene ring in formula (2). The bond position of the vinyl group is R 2 -X 2 The group is in the ortho, meta, or para position. The para position is preferred. The benzene ring may also have other substituents besides the vinyl group. Other substituents include, for example, C 1-5 Alkyl alkyl group, C 6-10 Aryl group, C 7-12 Aralkyl group, hydroxyl group, C 1-5 Alkoxy group, C 6-10 Aryloxy group, C 7-12 Aralkyloxy group, C 1-5 Examples include acyloxy groups. Furthermore, aromatic or non-aromatic hydrocarbon rings or aromatic or non-aromatic heterocycles may be fused to the benzene ring. 【0019】 The amount of compound represented by formula (1) used is, for example, 0.01 to 0.20 moles, preferably 0.01 to 0.10 moles, and particularly preferably 0.03 to 0.07 moles, per mole of metallic magnesium. When the compound represented by formula (1) is used within this range, metallic magnesium is rapidly activated, and the reaction with the compound represented by formula (2) proceeds rapidly. If the amount of compound represented by formula (1) present in the system falls below this range, the reaction between the compound represented by formula (2) and metallic magnesium tends to be suppressed, especially if water is present in the system. Conversely, if the amount of compound represented by formula (1) present in the system exceeds this range, the amount of by-products tends to increase. 【0020】 The amount of compound represented by formula (2) used is, for example, 0.90 to 1.10 moles, preferably 1.00 to 1.05 moles, per mole of metallic magnesium. 【0021】 The above reaction can be carried out in the presence of a solvent. Examples of the solvent include ether-based solvents such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, and cyclopentyl methyl ether. These can be used individually or in combination of two or more. 【0022】 The solvent preferably has a low water content, with the water content being, for example, 0.1% by weight or less, and more preferably 0.05% by weight or less, of the total amount of the solvent. 【0023】 The amount of solvent used is, for example, about 2.5 to 3.5 times the weight of the total amount of the compound represented by formula (2) and metallic magnesium. If the amount of solvent used exceeds this range, the concentration of the reactants decreases, and the reaction rate tends to decrease. 【0024】 The reaction atmosphere is not particularly limited as long as it does not inhibit the reaction, and may be any atmosphere such as a nitrogen atmosphere or an argon atmosphere. 【0025】 When the above reaction is carried out in the presence of a solvent, it is preferable to first dissolve the metallic magnesium and the compound represented by formula (1) in the solvent by heating and stirring, and then add the compound represented by formula (2). 【0026】 The reaction temperature between the compound represented by formula (2) and metallic magnesium is, for example, 20°C or lower (e.g., 0 to 20°C), preferably 15°C or lower, and particularly preferably 10°C or lower. Although the reaction in step 1 is an exothermic reaction, in the manufacturing method of this disclosure, since metallic magnesium is activated using the compound represented by formula (1), the reaction can be started at a low temperature. Furthermore, the amount of heat generated can be suppressed, and the reaction can proceed safely. 【0027】 The reaction time is, for example, about 0.5 to 20 hours. 【0028】 The reaction can be carried out using any method, such as batch, semi-batch, or continuous. The end of the reaction can be determined by checking the remaining amount of the compound represented by formula (2) using GC analysis or the like. After the reaction is complete, the reaction product, the compound represented by formula (3), may be subjected to general separation and purification treatments (e.g., precipitation, washing, filtration, etc.). Alternatively, the reaction in step 2 may be carried out without separating and purifying the compound represented by formula (3). In other words, the reactions in steps 1 and 2 may be carried out in a single pot. 【0029】 (Process 2) Step 2 is a step in which the compound represented by formula (3) obtained in Step 1 is reacted (coupling reaction) with the compound represented by the following formula (2') to obtain a divinyl-substituted aromatic compound represented by the following formula (4). [ka] 【0030】 In the above formula, R 2 , R 3 These are identical or different, representing a single bond or an alkylene group having 1 to 5 carbon atoms. 2 , X 3 These represent halogen atoms, either identical or distinct. Note that R 2 , X 2 The same applies as above. 【0031】 The aforementioned R 3 The alkylene group having 1 to 5 carbon atoms in the above R is 2 Similar examples include alkylene groups with 1 to 5 carbon atoms. 【0032】 The aforementioned X 3 The halogen atom in is the X 1 , X 2 A similar example can be given to halogen atoms. 【0033】 The compound represented by formula (2') may be the same compound as the compound represented by formula (2), or it may be a different compound. It can be appropriately selected depending on the divinyl-substituted aromatic compound to be produced. 【0034】 The amount of compound represented by formula (2') used is, for example, 0.9 to 1.1 moles, preferably 0.95 to 1.05 moles, per mole of the compound represented by formula (3). 【0035】 The above reaction can be carried out in the presence of a solvent. Examples of the solvent include ether-based solvents such as diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, dioxane, 1,2-dimethoxyethane, and cyclopentyl methyl ether. These can be used individually or in combination of two or more. 【0036】 The solvent preferably has a low water content, with the water content being, for example, 0.1% by weight or less, and more preferably 0.05% by weight or less, of the total amount of the solvent. 【0037】 The amount of solvent used is, for example, about 2.5 to 3.5 times the total amount of the compound represented by formula (2') and the compound represented by formula (3). If the amount of solvent used exceeds this range, the concentration of the reactants decreases, and the reaction rate tends to decrease. 【0038】 The reaction atmosphere is not particularly limited as long as it does not inhibit the reaction, and may be any atmosphere such as a nitrogen atmosphere or an argon atmosphere. 【0039】 The reaction temperature is, for example, 20°C or lower (e.g., 0-20°C), preferably 15°C or lower, and particularly preferably 10°C or lower. 【0040】 The reaction time is, for example, about 0.5 to 20 hours. 【0041】 The reaction can be carried out using any method, such as batch, semi-batch, or continuous. After the reaction is complete, the reaction product, the divinyl-substituted aromatic compound represented by formula (4), can be separated and purified by general precipitation, washing, and filtration. 【0042】 The divinyl-substituted aromatic compounds obtained in this manner are useful, for example, as materials for forming low dielectric constant insulating layers. Furthermore, electronic components equipped with insulating layers obtained using the divinyl-substituted aromatic compounds exhibit low dielectric loss and excellent high-frequency characteristics. 【0043】 The configurations and combinations thereof described above are examples only, and additions, omissions, substitutions, and modifications to the configurations may be made as appropriate, without departing from the spirit of this disclosure. [Examples] 【0044】 The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited by these examples, but is limited only by the claims. 【0045】 Example 1 (Process 1-1) In a nitrogen-purged flask, 1.19 moles of metallic magnesium and 1270 mL of tetrahydrofuran (water content: 0.05 wt%) were charged. 0.06 moles of methylmagnesium chloride were then added, and the mixture was stirred at 66.0°C for 30 minutes. The reaction mixture temperature after stirring was 66.3°C. 【0046】 (Step 1-2) Subsequently, 1.20 moles of 4-vinylbenzyl chloride were added dropwise to the flask and stirred at 7°C. The temperature inside the flask began to rise 5 minutes after stirring began, and 10 minutes after stirring began, the reaction solution was sampled, acetone was added, and it was analyzed by GC. No peak of 4-vinylbenzyl chloride was observed, but a peak indicating the formation of the Grinia reagent was observed. 【0047】 (Process 2) Subsequently, 1.20 moles of 4-vinylbenzyl chloride were added dropwise to the flask and stirred at 8°C. As a result, 1,2-bis(p-vinylphenyl)ethane was obtained (yield: 100%). 【0048】 Comparative Example 1 (Process 1-1) The procedure was carried out in the same manner as in Example 1, except that 0.004 moles of 1,2-dibromoethane was used instead of methylmagnesium chloride. (Step 1-2) The reaction began at a flask temperature of 25°C. The reaction then ended when the flask temperature rose to 57°C. (Process 2) The procedure was carried out in the same manner as in Example 1. As a result, 1,2-bis(p-vinylphenyl)ethane was obtained (yield: 93%). 【0049】 Comparative Example 2 In a nitrogen-purged flask, 0.039 moles of methylmagnesium chloride and 22 mL of tetrahydrofuran were charged, and 0.039 moles of 4-vinylbenzyl chloride were added dropwise. The mixture was then stirred at 5°C for 180 minutes. However, 1,2-bis(p-vinylphenyl)ethane could not be obtained.

Claims

[Claim 1] A method for producing a divinyl-substituted aromatic compound, comprising the following steps 1 and 2. Step 1: The following formula (1) R １ -Mg-X １ (1) (In the formula, R １ X represents an alkyl group having 1 to 5 carbon atoms. １ (This indicates a halogen atom.) In the presence of the compound represented by the following formula (2) 【Chemistry 1】 (In the formula, R ２ X represents a single bond or an alkylene group having 1 to 5 carbon atoms. ２ (This indicates a halogen atom.) The compound represented by is reacted with metallic magnesium to produce the following compound (3) 【Chemistry 2】 (In the formula, R ２ , X ２ (The same applies as above.) This is a process to obtain a compound represented by the following: The amount of the compound represented by formula (1) used is 0.01 to 0.20 moles per mole of metallic magnesium. The amount of compound represented by formula (2) used is 0.90 to 1.10 moles per mole of metallic magnesium. Step 2: The compound represented by formula (3) and the following formula (2') 【Transformation 3】 (wherein, R ３ represents a single bond or an alkylene group having 1 to 5 carbon atoms, and X ３ represents a halogen atom) The compound represented by the following formula (4) is reacted to obtain 【Chemistry 4】 (In the formula, R ２ , R ３ (The same applies as above.) A divinyl-substituted aromatic compound represented by the formula is obtained. [Claim 2] A method for producing a divinyl-substituted aromatic compound according to claim 1, wherein the reaction in step 1 is carried out under temperature conditions of 10°C or lower.

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