A process for the preparation of 1-methylbenzocyclobutene

Abstract

The application belongs to the technical field of dielectric material monomer synthesis, and discloses a preparation method of 1-methylbenzocyclobutene. The application adopts 1-hydroxybenzocyclobutene as raw material, and reacts with p-toluenesulfonyl chloride (TsCl) to generate 1-p-toluenesulfonyloxybenzocyclobutene. Then, the 1-p-toluenesulfonyloxybenzocyclobutene reacts with methylmagnesium chloride under the action of a catalyst to obtain the target product 1-methylbenzocyclobutene. The target product is synthesized under relatively mild conditions mainly by controlling the reaction temperature, the feeding sequence and the feeding ratio. The process operation is simple, the experimental condition is mild, the product yield is high, and the method is suitable for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of dielectric material monomer synthesis, and particularly relates to a preparation method of 1-methylbenzocyclobutene. BACKGROUND

[0002] 1-methylbenzocyclobutene is a dielectric material monomer, has excellent physical properties, chemical stability and high-temperature stability, and can be widely applied to the fields of electronics, microelectronics industry manufacturing and the like. At present, the preparation methods of 1-methylbenzocyclobutene are generally divided into two kinds, one is to react 1-hydroxymethylbenzocyclobutene with p-toluenesulfonyl chloride and then reduce by using lithium aluminum hydride, or to prepare by hydrogen reduction of 1-vinylbenzocyclobutene, both of which involve reduction reaction, and the industrial scale-up has high risk coefficient, is inconvenient to prepare, and has low production efficiency. SUMMARY

[0003] The present application aims to provide a preparation method of 1-methylbenzocyclobutene to solve the technical problems in the background.

[0004] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0005] A preparation method of 1-methylbenzocyclobutene, comprising the following steps:

[0006] S1: preparing raw materials;

[0007] The raw materials include 1-hydroxybenzocyclobutene, dichloromethane, triethylamine, p-toluenesulfonyl chloride, tetrahydrofuran, iron acetylacetone, methyl magnesium chloride THF solution, saturated ammonium chloride solution and ethyl acetate;

[0008] S2: preparing 1-p-toluenesulfonyloxybenzocyclobutene;

[0009] A reaction bottle is prepared, 1-hydroxybenzocyclobutene and dichloromethane are added into the reaction bottle, the solution is stirred to make the 1-hydroxybenzocyclobutene completely dissolved in the dichloromethane, then triethylamine is added, then p-toluenesulfonyl chloride is added, then the reaction is kept for 1-2 hours to obtain a reaction liquid, whether the chemical reaction is completely finished is detected, the reaction liquid after the chemical reaction is completely finished is poured into ice water, stirred for 30 minutes, and then separated into layers, the reaction liquid after the separation is extracted to obtain organic phase and aqueous phase, and the organic phase is washed, dried, filtered, concentrated to obtain 1-p-toluenesulfonyloxybenzocyclobutene.

[0010] S3: preparing 1-methylbenzocyclobutene;

[0011] Prepare three flasks, add 1-p-tolylsulfonyloxy benzocyclobutene obtained in step S2 into the flasks, then add tetrahydrofuran, then stir to completely dissolve 1-p-tolylsulfonyloxy benzocyclobutene, then add acetylacetone iron, cool the system to-20℃, then drop methyl magnesium chloride THF solution into the flask, and let it react for 2 hours at-30℃ to-20℃ to obtain the primary product, detect whether the chemical reaction is completely finished, pour the primary product into saturated ammonium chloride solution for acidification, and after the primary product is completely acidified, add ethyl acetate to the primary product, stir and stand, and wait for the solution to separate into organic phase and aqueous phase, separate the organic phase and the aqueous phase, extract the aqueous phase with ethyl acetate again to obtain the residual organic phase in the aqueous phase, and combine the obtained organic phases, wash, dry, and concentrate and distill to obtain 1-methyl benzocyclobutene.

[0012] Preferably, in step S2, the mass-volume ratio of 1-hydroxybenzocyclobutene to dichloromethane is 1g:5-10mL, and the molar ratio of 1-hydroxybenzocyclobutene, triethylamine, and p-toluenesulfonyl chloride is 1:1.2-1.7:1-1.4.

[0013] Preferably, in step S3, the mass-volume ratio of 1-p-tolylsulfonyloxy benzocyclobutene to tetrahydrofuran is 1g:5-8mL, and the molar ratio of 1-p-tolylsulfonyloxy benzocyclobutene, acetylacetone iron, and methyl magnesium chloride THF solution is 1:0.005-0.01:1.0-1.5.

[0014] Preferably, in step S2, p-toluenesulfonyl chloride is added in batches, and the temperature during the feeding process is-10℃ to-5℃.

[0015] Preferably, in step S2, the organic phase is first washed with HCl, then washed with saturated sodium bicarbonate aqueous solution, and finally washed with saturated brine, and dried by anhydrous magnesium sulfate.

[0016] Preferably, in step S3, methyl magnesium chloride THF solution is dropped into the flask using a constant pressure dropping funnel, and the temperature of the reaction system during the dropping of methyl magnesium chloride THF solution is-30℃ to-20℃.

[0017] Preferably, in steps S2 and S3, thin layer chromatography is used to detect whether the reaction is completely finished.

[0018] Preferably, in step S3, the organic phase is washed with saturated brine, dried by anhydrous sodium sulfate, and purified by reduced pressure distillation using a high vacuum oil pump.

[0019] The technical scheme produces the beneficial effects that:

[0020] (1) the technical scheme changes the preparation raw material, adopts 1-hydroxybenzocyclobutene as the raw material, reacts with p-toluenesulfonyl chloride and other substances to generate the target product (1-methylbenzocyclobutene), through setting the reaction temperature and the feeding step, 1-methylbenzocyclobutene is synthesized under relatively mild conditions, the raw material cost is low and convenient to obtain, the production cost is greatly reduced; the experimental condition is mild, the process operation is simple, the industrial amplification risk coefficient is greatly reduced, and the industrial production is suitable; the feeding proportion of each substance is optimized, the product generation rate is greatly improved, and the preparation efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The nuclear magnetic resonance hydrogen spectrum of 1-methylbenzocyclobutene synthesized by the application; DETAILED DESCRIPTION

[0022] The applicant will further illustrate the application in detail by combining specific examples, and the purpose is to enable those skilled in the art to more clearly understand the application, but the following content should not be understood as limiting the scope of the claims of the application. If not specifically indicated, the technical means used in the examples are conventional means known to those skilled in the art, and the materials, reagents and the like used can be obtained from commercial channels: Example 1

[0023] A preparation method of 1-methylbenzocyclobutene, comprising the following steps:

[0024] S1: preparing raw materials;

[0025] The raw materials include 1-hydroxybenzocyclobutene, dichloromethane, triethylamine, p-toluenesulfonyl chloride, tetrahydrofuran, acetylacetone iron, methyl magnesium chloride THF solution, saturated ammonium chloride solution and ethyl acetate; the rest of the experimental instruments such as reaction bottles, flasks and the like are also prepared before starting operation, and the raw materials prepared in the application S1 are the substances prepared for the chemical reaction of the target product;

[0026] S2: preparing 1-p-toluenesulfonyloxybenzocyclobutene;

[0027] A 250ml reaction flask was prepared, 1-hydroxybenzocyclobutene 12.0g (100mmol) was added into the reaction flask, then 100ml dichloromethane was added, the solution was stirred to make 1-hydroxybenzocyclobutene completely dissolved in dichloromethane, then 20.85ml triethylamine (150mmol) was added, then 22.88g p-toluenesulfonyl chloride (120mmol) was added, the p-toluenesulfonyl chloride was added in batches, the temperature of the added liquid was controlled at -10℃, that is, the solution in the reaction flask was reduced to -10℃, then the tosyl chloride was added into the reaction flask, the temperature of the reaction system was kept at -10℃ when the tosyl chloride was added, then the substances in the reaction flask were incubated in an ice-salt bath at -10℃ for 1-2 hours, thin layer chromatography was used to detect whether the reaction was completely carried out, and the reaction liquid was obtained after the chemical reaction was completely finished;

[0028] The reaction liquid was poured into 200ml ice water, stirred for 30 minutes, and then separated into layers. The separated reaction liquid was extracted to obtain organic phase and aqueous phase, and then the organic phase was washed with 100ml 1N HCl, 100ml saturated sodium bicarbonate aqueous solution and saturated brine in turn, and then dried with anhydrous magnesium sulfate. Then it was filtered and concentrated to remove the solvent to obtain 1-p-toluenesulfonyloxybenzocyclobutene.

[0029] S3: Preparation of 1-methylbenzocyclobutene;

[0030] A three-necked flask was prepared, 1-p-toluenesulfonyloxybenzocyclobutene 13.72g (50mmol) obtained in step S2 was added into the flask, then 60ml tetrahydrofuran was added, then the 1-p-toluenesulfonyloxybenzocyclobutene was stirred to dissolve, then 0.088g acetylacetone iron (0.25mmol) was added, the reaction system was cooled to -20℃, that is, the reaction substances in the flask were cooled to -20℃, then 32.5ml 2M methylmagnesium chloride THF solution (65mmol) was added into the flask, the methylmagnesium chloride THF solution was added into the flask by constant pressure dropping funnel, and the temperature of the reaction system was kept at -20℃ during the dropping process of the methylmagnesium chloride THF solution; then the solution was reacted at -20℃ for 2 hours, and whether the chemical reaction was completely finished was detected by thin layer chromatography, and the preliminary product was obtained after the reaction was completely finished;

[0031] The primary product is then slowly poured into 100 ml of saturated ammonium chloride solution for acidification, and after the acidification is complete, an acidified primary product is obtained. 60 ml of ethyl acetate is added to the acidified primary product, which is stirred and then allowed to stand, waiting for the solution to separate into layers, and then extracted to obtain an organic phase and an aqueous phase. The obtained aqueous phase is again extracted with 100 ml of ethyl acetate, and the organic phases obtained by the two extractions are combined. The organic phase is washed with saturated brine, dried with anhydrous sodium sulfate, and concentrated to remove the solvent to obtain a crude product, which is then subjected to reduced pressure distillation by a high vacuum oil pump to obtain the target product 1-methylbenzocyclobutene in the form of an oily liquid 4.72 g, with a total yield of 70%.

[0032] The temperature control of the reaction system described above is controlled by an ice-salt bath, which is a general conventional technique in the art and will not be described here. Example 2

[0033] A method for preparing 1-methylbenzocyclobutene, comprising the following steps:

[0034] S1: preparing raw materials;

[0035] The raw materials include 1-hydroxybenzocyclobutene, dichloromethane, triethylamine, p-toluenesulfonyl chloride, tetrahydrofuran, iron acetylacetone, methyl magnesium chloride THF solution, saturated ammonium chloride solution, and ethyl acetate. The remaining experimental instruments such as reaction bottles, flasks, etc. are also prepared before starting the operation. The raw materials prepared in S1 of the present application are substances required for the preparation of the target product chemical reaction;

[0036] S2: preparing 1-p-toluenesulfonyloxybenzocyclobutene;

[0037] A 250 ml reaction bottle is prepared, 1-hydroxybenzocyclobutene 12.0 g (100 mmol) is added to the reaction bottle, then 100 ml of dichloromethane is added, the solution is stirred to make the 1-hydroxybenzocyclobutene completely dissolved in the dichloromethane, then 20.85 ml of triethylamine (150 mmol) is added, then 22.88 g of p-toluenesulfonyl chloride (115 mmol) is added. When adding p-toluenesulfonyl chloride, 22.88 g of p-toluenesulfonyl chloride is added to the reaction bottle in batches, and the addition temperature is controlled at -10°C, that is, the solution in the reaction bottle is reduced to -10°C, then the p-toluenesulfonyl chloride is added to the reaction bottle, and the temperature of the reaction system is maintained at -10°C when the p-toluenesulfonyl chloride is added. Then the substances in the reaction bottle are incubated at -10°C in an ice-salt bath for 1-2 hours. Thin layer chromatography is used to detect whether the reaction is completely carried out. After the chemical reaction is completely finished, a reaction liquid is obtained.

[0038] The reaction solution is poured into 200 ml of ice water, stirred for 30 minutes, and allowed to separate into layers. The separated reaction solution is extracted to obtain an organic phase and an aqueous phase. The organic phase is then washed with 100 ml of 1N HCl, 100 ml of saturated sodium bicarbonate aqueous solution, and saturated brine, respectively. The washed organic phase is then dried over anhydrous magnesium sulfate, filtered, and concentrated to remove the solvent, thereby obtaining 1-p-tolylsulfonyloxybenzocyclobutene.

[0039] S3: Preparation of 1-methylbenzocyclobutene

[0040] A three-necked flask is prepared, and 13.72 g (50 mmol) of 1-p-tolylsulfonyloxybenzocyclobutene obtained in step S2 is added to the flask. Then, 60 ml of tetrahydrofuran is added, and the 1-p-tolylsulfonyloxybenzocyclobutene is stirred to be dissolved. Then, 0.088 g of iron acetylacetonate (0.25 mmol) is added, and the reaction system is cooled to -20°C. Then, 32.5 ml of 2M methylmagnesium chloride THF solution (65 mmol) is added to the flask using a constant pressure dropping funnel. During the addition of the methylmagnesium chloride THF solution, the temperature of the reaction system is maintained at -20°C. Then, the temperature of the reaction system is lowered to -25°C, and the reaction system is allowed to react at -25°C for 2 hours. Whether the chemical reaction is completed is determined by thin layer chromatography. After the reaction is completed, a preliminary product is obtained.

[0041] Then, the preliminary product is slowly poured into 100 ml of saturated ammonium chloride solution to be acidified. After the acidification is completed, an acidified preliminary product is obtained. Then, 60 ml of ethyl acetate is added to the acidified preliminary product, which is stirred and allowed to stand. After the solution is separated into layers, an organic phase and an aqueous phase are extracted. The obtained aqueous phase is again extracted with 100 ml of ethyl acetate. The organic phases obtained by the two extractions are combined, washed with saturated brine, dried over anhydrous sodium sulfate, concentrated to remove the solvent, and then distilled under reduced pressure using a high vacuum oil pump, thereby obtaining the target product 1-methylbenzocyclobutene as an oily liquid. The total yield is 68%.

[0042] As can be seen from the comparison between Example 2 and Example 1, when the reaction temperature is changed, the chemical reaction of the substance is affected, thereby affecting the conversion rate of the finished product. Example 3

[0043] A method for preparing 1-methylbenzocyclobutene includes the following steps:

[0044] S1: Preparation of raw materials

[0045] The raw materials include 1-hydroxybenzocyclobutene, dichloromethane, triethylamine, p-toluenesulfonyl chloride, tetrahydrofuran, acetylacetone iron, methyl magnesium chloride THF solution, saturated ammonium chloride solution and ethyl acetate; the remaining experimental instruments such as reaction bottles, flasks, etc. are also prepared together before starting the operation, and the raw materials prepared in S1 of the application are the substances required for the preparation of the target product chemical reaction;

[0046] S2: Preparation of 1-p-toluenesulfonyloxybenzocyclobutene;

[0047] A 250ml reaction bottle is prepared, 1-hydroxybenzocyclobutene 12.0g (100mmol) is added to the reaction bottle, then 100ml dichloromethane is added, the solution is stirred to make 1-hydroxybenzocyclobutene completely dissolved in dichloromethane, then 22.24ml triethylamine (160mmol) is added, then 24.80g p-toluenesulfonyl chloride (130mmol) is added, the p-toluenesulfonyl chloride is added in batches to the reaction bottle, the temperature of the added material is controlled at -10℃, that is, the solution in the reaction bottle is reduced to -10℃, then the p-toluenesulfonyl chloride is added to the reaction bottle, the temperature of the reaction system is kept at -10℃ when the p-toluenesulfonyl chloride is added, then the substances in the reaction bottle are incubated in an ice-salt bath at -10℃ for 1-2 hours, thin layer chromatography is used to detect whether the reaction is completely carried out, and the reaction liquid is obtained after the chemical reaction is completely finished;

[0048] The reaction liquid is poured into 200ml ice water, stirred for 30 minutes, and then separated into layers, and the separated reaction liquid is extracted to obtain organic phase and aqueous phase, then the organic phase is washed with 100ml 1N HCl, 100ml saturated sodium bicarbonate aqueous solution and saturated brine in turn, then the washed organic phase is dried by anhydrous magnesium sulfate, then filtered and concentrated to remove the solvent, to obtain 1-p-toluenesulfonyloxybenzocyclobutene.

[0049] S3: Preparation of 1-methylbenzocyclobutene;

[0050] Prepare three mouth flask, to flask add 1-p-tolylsulfonyloxy benzocyclobutene 13.72 g (50 mmol) obtained in step S2, then add 60 ml tetrahydrofuran, then stir to dissolve 1-p-tolylsulfonyloxy benzocyclobutene, then add 0.088 g acetylacetone iron (0.25 mmol), the reaction system is cooled to-20 DEG C, that is, the reaction material in the flask is cooled to-20 DEG C, then add 30 ml 2M methyl magnesium chloride THF solution (60 mmol) to the flask, the methyl magnesium chloride THF solution is added dropwise into the flask using constant pressure dropping funnel, the temperature of the methyl magnesium chloride THF solution is kept at-20 DEG C during the dropwise addition; then the solution is reacted at-20 DEG C for 2 hours, whether the chemical reaction is completely finished is detected by thin layer chromatography, after the reaction is completely finished, the preliminary product is obtained;

[0051] Then the preliminary product is slowly poured into 100 ml saturated ammonium chloride solution for acidification, after the acidification is completed, the acidified preliminary product is obtained, 60 ml ethyl acetate is added to the acidified preliminary product, after stirring, it is placed, and then the solution is layered, and then the organic phase and the aqueous phase are extracted, the obtained aqueous phase is extracted again with 100 ml ethyl acetate, the organic phases obtained by twice extraction are combined, the organic phase is washed with saturated brine, dried with anhydrous sodium sulfate, and concentrated to remove the solvent to obtain a crude product, and then the target product 1-methyl benzocyclobutene is obtained by reduced pressure distillation through a high vacuum pump, and an oily liquid 4.63 g is obtained, and the total yield is 68.7%.

[0052] The technical scheme provided in the application changes the raw material and method for preparing the target product, and the target product is prepared by a brand new method. By limiting the reaction temperature, the feeding steps and the proportion of the raw materials, 1-methyl benzocyclobutene is synthesized under relatively mild conditions. The raw material used is low in cost and easy to obtain, which greatly reduces the production cost. The experimental conditions are mild, the process operation is simple, the risk coefficient of industrial amplification is greatly reduced, and the industrial production is suitable. The proportion of each substance is optimized, the product yield is greatly improved, and the preparation efficiency is improved.

[0053] The above is only an embodiment of the application, and the specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical scheme of the application, some modifications and improvements can be made, which should also be considered as the protection scope of the application, which will not affect the effect and practicality of the application. The protection scope claimed in the application should be subject to the content of its claims, and the specific implementation mode and the like in the description can be used to explain the content of the claims.

Claims

1. A method for preparing 1-methylbenzocyclobutene, characterized in that: The following steps are involved: S1: Prepare raw materials; The raw materials include 1-hydroxybenzocyclobutene, dichloromethane, triethylamine, p-toluenesulfonyl chloride, tetrahydrofuran, ferric acetylacetonate, methylmagnesium chloride THF solution, saturated ammonium chloride solution and ethyl acetate; S2: Preparation of 1-p-toluenesulfonyloxybenzocyclobutene; Prepare a reaction flask, add the 1-hydroxybenzocyclobutene and dichloromethane into the reaction flask, stir the solution to completely dissolve the 1-hydroxybenzocyclobutene in the dichloromethane, then add triethylamine, then add p-toluenesulfonyl chloride, and then keep the mixture at a temperature of -10°C to -5°C for 1-2 hours to obtain a reaction solution, check whether the chemical reaction is completely completed, pour the reaction solution after the chemical reaction is complete into ice water, stir for 30 minutes, let it stand and separate, extract the separated reaction solution to obtain an organic phase and an aqueous phase, wash the organic phase, dry, filter, and concentrate to obtain 1-toluenesulfonyloxybenzocyclobutene; S3: Preparation of 1-methylbenzocyclobutene; Prepare a three-necked flask, add the 1-toluenesulfonyloxybenzocyclobutene obtained in step S2 into the flask, then add tetrahydrofuran, and then stir to dissolve the 1-toluenesulfonyloxybenzocyclobutene, then add ferric acetylacetonate, cool the reaction system to -20°C, and then drop methylmagnesium chloride THF solution into the flask, wait for it to react at -30°C to -20°C for 2 hours to obtain a preliminary product, detect whether the chemical reaction is completely completed, pour the preliminary product after the chemical reaction is completely completed into a saturated ammonium chloride solution for acidification, wait until the preliminary product is completely acidified, add ethyl acetate to the preliminary product, stir and then stand, wait for the solution to separate to obtain an organic phase and an aqueous phase, separate the organic phase and the aqueous phase, extract the obtained aqueous phase with ethyl acetate to obtain an organic phase remaining in the aqueous phase, combine the obtained organic phases, wash, dry, concentrate and distill the organic phases to obtain 1-methylbenzocyclobutene; In step S2, the mass volume ratio of 1-hydroxybenzocyclobutene to dichloromethane is 1 g: 5-10 mL, and the molar ratio of 1-hydroxybenzocyclobutene, triethylamine, and p-toluenesulfonyl chloride is 1:1.2-1.7:1-1.4; In step S3, the mass volume ratio of 1-toluenesulfonyloxybenzocyclobutene to tetrahydrofuran is 1 g: 5-8 mL, and the molar ratio of 1-toluenesulfonyloxybenzocyclobutene, ferric acetylacetonate, and methylmagnesium chloride in the THF solution is 1:0.005-0.01:1.0-1.5; In step S2, p-toluenesulfonyl chloride is added in batches, and the temperature of the reaction system during the addition process is -10°C to -5°C.

2. The method for preparing 1-methylbenzocyclobutene according to claim 1, wherein In step S2, the organic phase is first washed with HCl, then washed with a saturated sodium bicarbonate aqueous solution, and finally washed with saturated brine, and dried over anhydrous magnesium sulfate.

3. The method for preparing 1-methylbenzocyclobutene according to claim 1, wherein In the step S3, the methylmagnesium chloride THF solution is dripped into the flask using a constant pressure dropping funnel, and the temperature of the reaction system is -30°C to -20°C when the methylmagnesium chloride THF solution is dripped.

4. The method for preparing 1-methylbenzocyclobutene according to claim 1, wherein In step S2 and step S3, thin layer chromatography is used to detect whether the reaction is completely completed.

5. The method for preparing 1-methylbenzocyclobutene according to claim 1, wherein In step S3, the organic phase is washed with saturated brine, dried over anhydrous sodium sulfate, and purified by reduced pressure distillation using a high vacuum oil pump.

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