Method for synthesizing 4-tert-butoxystyrene

Abstract

The invention provides a method for synthesizing 4-tert-butoxystyrene, which comprises the following steps: firstly, synthesizing 4-tert-butoxyacetophenone by taking 4-hydroxyacetophenone and isobutene as raw materials; 4-tert-butoxyacetophenone and hydrogen are used as raw materials, a phenanthroline-iridium complex is used as a hydrogenation catalyst, and 4-tert-butoxyphenyl methyl alcohol is synthesized; and dehydrating the 4-tert-butoxy phenyl methyl alcohol to generate the 4-tert-butoxy styrene. 4-tert-butoxystyrene is synthesized through three-step reaction of tert-butoxylation, catalytic hydrogenation and catalytic dehydration, a phenanthroline-iridium complex is adopted as a hydrogenation catalyst in catalytic hydrogenation, tert-butoxystyrene functional groups cannot be affected during carbonyl hydrogenation, and 4-tert-butoxystyrene can be synthesized under mild conditions. And 4-tert-butoxy phenyl methyl alcohol is prepared with high selectivity.

Description

Technical Field

[0001] The invention belongs to the technical field of photoresist material preparation, relates to 4-tert-butoxystyrene, and specifically relates to a method for synthesizing 4-tert-butoxystyrene. Background Art

[0002] Photoresist, also known as photoresist, refers to a corrosion-resistant thin film material whose solubility changes through irradiation or radiation of ultraviolet light, electron beam, particle beam, x-ray, etc. Photoresist is a key material for completing the photolithography process in microelectronics manufacturing, and it determines the development level of microelectronics technology. From the development trend of photoresist, at present, both domestically and abroad, ultraviolet photoresist has entered a mature stage and has been mass-produced, but the localization process of 248nm deep ultraviolet photoresist is relatively slow. With the continuous deepening of the research on phenolic resin system photoresist, it is found that the resin material polymerized with 4-tert-butoxystyrene as the main monomer has good light transmittance at 248nm, contains a large number of benzene rings in its structure, has strong etching resistance, and has the potential to be developed by alkaline water, making it an ideal main resin material for 248nm deep ultraviolet photoresist, and has been industrialized in some developed countries. Therefore, the development of the synthesis process of 4-tert-butoxystyrene is of great significance in China.

[0003] There are few methods for synthesizing 4-tert-butoxystyrene in the prior art. The Chinese patent with application number CN202310086049.2 reports a method for synthesizing 4-tert-butoxystyrene, which uses bromobenzene as the starting material, etherifies under heating conditions of potassium tert-butoxide, cuprous iodide and dimethyl sulfoxide to obtain phenyl tert-butyl ether; then uses N-bromosuccinimide to carry out bromination reaction to obtain 4-tert-butoxybromobenzene, and finally 4-tert-butoxybromobenzene and vinyl magnesium chloride are coupled under the action of palladium catalyst to obtain 4-tert-butoxystyrene. The above method uses expensive reagents such as bromobenzene and N-bromosuccinimide, and the synthesis cost is high; the use of strong bases such as potassium tert-butoxide and dimethyl sulfoxide will produce a large amount of wastewater; the palladium-catalyzed vinyl magnesium chloride coupling reaction has high equipment requirements and is difficult to operate; the above factors seriously restrict the industrial application of the method. Chinese patent application number CN201810185891.0 reports a method for preparing 3-tert-butoxystyrene and its derivatives, which involves the preparation of a Grignard reagent and a nickel-catalyzed Kumada coupling reaction, and has high operating requirements, great safety risks, and high synthesis costs. Summary of the invention

[0004] In view of the defects and shortcomings of the prior art, the purpose of the present invention is to provide a method for synthesizing 4-tert-butoxystyrene, so as to solve the technical problems in the prior art of synthesizing 4-tert-butoxystyrene, such as harsh reaction conditions, complex process routes, high operating requirements, great safety risks and large amounts of three wastes.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A method for synthesizing 4-tert-butoxystyrene comprises the following steps: firstly, using 4-hydroxyacetophenone and isobutylene as raw materials to synthesize 4-tert-butoxyacetophenone; then, using 4-tert-butoxyacetophenone and hydrogen as raw materials and using a phenanthroline-iridium complex as a hydrogenation catalyst to synthesize 4-tert-butoxyphenylmethyl alcohol; and then, dehydrating 4-tert-butoxyphenylmethyl alcohol to generate 4-tert-butoxystyrene.

[0007] The chemical structure of the phenanthroline-iridium complex is shown in the following formula I:

[0008]

[0009] In Formula I:

[0010] R1 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl;

[0011] R2 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl;

[0012] R3 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl.

[0013] The present invention also has the following technical features:

[0014] Preferably, the phenanthroline-iridium complex is selected from the phenanthroline-iridium complex Cat 2 shown in Formula I-2 and the phenanthroline-iridium complex Cat 3 shown in Formula I-3:

[0015]

[0016] Specifically, the molar ratio of 4-tert-butoxyacetophenone to the hydrogenation catalyst is 1:(0.01-0.05). Preferably, the mass ratio of 4-tert-butoxyacetophenone to phenanthroline-iridium complex Cat 2 is 19:1.1; the mass ratio of 4-tert-butoxyacetophenone to phenanthroline-iridium complex Cat 3 is (19-96):(0.64-3.2).

[0017] Specifically, the method comprises the following steps:

[0018] Step 1, synthesis of 4-tert-butoxyacetophenone:

[0019] 4-Hydroxyacetophenone and a first acid catalyst are added to a first reaction solvent, and isobutylene gas is introduced to cause an etherification reaction to generate a crude product of 4-tert-butoxyacetophenone; the first acid catalyst is selected from trifluoromethanesulfonic acid, methanesulfonic acid, sulfuric acid, acetic acid, and trifluoroacetic acid; and the first reaction solvent is selected from one or more of dichloromethane, dichloroethane, ethyl acetate, and tetrahydrofuran.

[0020] Step 2, synthesis of 4-tert-butoxyphenyl methyl alcohol:

[0021] The 4-tert-butoxyacetophenone prepared in step 1 is dissolved in a second reaction solvent, and a hydrogenation reaction is carried out under a hydrogen atmosphere to generate a crude product of an intermediate 4-tert-butoxyphenylmethyl alcohol; the second reaction solvent is selected from one or more of methanol, ethanol and water.

[0022] Step 3, synthesis of 4-tert-butoxystyrene:

[0023] The 4-tert-butoxyphenyl methyl alcohol prepared in step 2 is dissolved in a third reaction solvent, and a dehydration reaction is carried out under the action of a second acid catalyst to generate a crude product of 4-tert-butoxystyrene; the second acid catalyst is selected from a hydrochloric acid dioxane solution, pyridine hydrochloride, stannous chloride, bismuth trifluoromethanesulfonate, and hydrochloric acid; and the third reaction solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and toluene.

[0024] Specifically, in step 1, the reaction temperature of the etherification reaction is 0-40°C, and the reaction time is 4-8 hours. Preferably, the reaction temperature of the etherification reaction is 15-25°C, and the reaction time is 5-6 hours.

[0025] Specifically, in step 1, the molar ratio of 4-hydroxyacetophenone to the first acid catalyst is 1:(0.02-0.06). Preferably, the mass ratio of 4-hydroxyacetophenone to trifluoromethanesulfonic acid is (68-136):(1.2-1.5); the mass ratio of 4-hydroxyacetophenone to methanesulfonic acid is 68:1.2.

[0026] Specifically, in step 2, the reaction temperature of the hydrogenation reaction is 30-80°C, and the reaction time is 3-8 hours. Preferably, the reaction temperature of the hydrogenation reaction is 60°C, and the reaction time is 4-6 hours.

[0027] Specifically, in step 2, the pressure of the hydrogen atmosphere is 0.1-0.8 MPa, preferably 0.2 MPa.

[0028] Specifically, in step 3, the reaction temperature of the dehydration reaction is 80-120° C., and the reaction time is 4-10 hours. Preferably, the reaction temperature of the dehydration reaction is 90-100° C., and the reaction time is 6-8 hours.

[0029] Specifically, in step 3, the molar ratio of the 4-tert-butoxyphenylmethyl alcohol to the second acid catalyst is 1:(0.01-0.05). Preferably, the mass ratio of 4-tert-butoxyphenylmethyl alcohol to trifluoromethanesulfonic acid is (68-136):(1.2-1.5); the mass ratio of 4-hydroxyacetophenone to methanesulfonic acid is 68:1.2.

[0030] Specifically, the step 1 also includes the following process: adding 30wt.% sodium hydroxide solution and water to the crude product of 4-tert-butoxyacetophenone in an ice water bath, adjusting the pH value to 11, controlling the internal temperature to 15-25°C, stirring for 10-60 minutes and then standing to separate the layers, back-extracting the aqueous phase with dichloromethane, combining the organic phases, adding sodium sulfate to dry; after drying, filtering out the sodium sulfate, performing reduced pressure distillation on the filtrate, beating the obtained solid slurry with petroleum ether, and filtering to obtain the pure product of 4-tert-butoxyacetophenone.

[0031] Specifically, the step 2 also includes the following process: distilling the crude product of 4-tert-butoxystyrene under reduced pressure to remove the solvent, adding n-hexane to the mother liquor and stirring it, filtering it, eluting the filter cake with n-hexane, distilling the filtrate under reduced pressure to remove the solvent, and performing short-range reduced pressure distillation again to obtain a pure product of 4-tert-butoxyphenyl methyl alcohol.

[0032] Specifically, the step three also includes the following process: adding water and ethyl acetate to the crude product of 4-tert-butoxystyrene, stirring thoroughly and then standing to separate the layers, stripping the aqueous phase with ethyl acetate, combining the organic phases, washing with saturated brine, and adding sodium sulfate to dry; after drying, filtering out the sodium sulfate, distilling the filtrate to remove the ethyl acetate, adding the inhibitor 4-tert-butylcatechol, and purifying again by short-range vacuum distillation to obtain pure 4-tert-butoxystyrene.

[0033] The beneficial technical effects of the present invention compared with the prior art are as follows:

[0034] (I) The present invention adopts a three-step reaction of "tert-butoxylation-catalytic hydrogenation-catalytic dehydration" to synthesize 4-tert-butoxystyrene, wherein the "catalytic hydrogenation" uses a phenanthroline-iridium complex as a hydrogenation catalyst, which will not affect the tert-butoxy functional group when hydrogenating the carbonyl group, and can prepare 4-tert-butoxyphenyl methyl alcohol with high selectivity under mild conditions.

[0035] (II) The present invention provides a universal green synthesis method for aryl alkyl methanol compounds, which has the advantages of simple process route, mild reaction conditions, less three wastes, high atom economy, etc., and is in line with the development trend of green chemical industry.

[0036] (III) The product yield of the present invention is high, and the finally obtained 4-tert-butoxystyrene has high purity and can be used to prepare 248nm deep ultraviolet photoresist. DETAILED DESCRIPTION

[0037] It should be noted that all raw materials and reagents used in the present invention, unless otherwise specified, are raw materials and reagents known in the art. For example, phenanthroline-iridium complex is a compound known in the prior art, which is recorded in Chinese patent application number 201810576123.8.

[0038] In accordance with the above technical scheme, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention.

[0039] Embodiment 1:

[0040] This embodiment provides a method for synthesizing 4-tert-butoxyacetophenone, which comprises the following steps:

[0041] Step 1.1, etherification reaction: add 136g of 4-hydroxyacetophenone, 1.5g of trifluoromethanesulfonic acid and 400g of dichloromethane to a 1L autoclave, stir until the solid is dissolved, cool in an ice-water bath, introduce isobutylene gas, maintain the system pressure at 0.15MPa, maintain the system temperature at 20±5°C, react for 6h, take samples for central control, the conversion rate of raw material 4-hydroxyacetophenone is 92.3%, stop the reaction, and obtain a crude product of 4-tert-butoxyacetophenone.

[0042] Step 1.2, post-treatment: In an ice-water bath, add 1.6 g of 30 wt.% sodium hydroxide solution and 40 g of water to the crude product of 4-tert-butoxyacetophenone, adjust the pH to 11, control the internal temperature to 20±2°C, stir thoroughly for 30 min, re-measure the pH if it remains unchanged, let stand to separate, extract the aqueous phase once with 40 g of dichloromethane, combine the organic phases, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, and distill the filtrate under reduced pressure. The resulting solid slurry is slurried with 400 g of petroleum ether and filtered to obtain 165 g of a white solid product.

[0043] Product identification: The white solid product was identified by nuclear magnetic resonance spectroscopy, and the results are as follows: 1H NMR (500MHz, CDCl3) δ7.89 (d, J = 8.6 Hz, 2H), 7.03 (d, J = 8.6 Hz, 2H), 2.56 (s, 3H), 1.42 (s, 9H). 13 C NMR (126MHz, CDCl3) δ197.0, 160.4, 131.8, 129.8, 122.3, 79.6, 28.9, 26.4. From the above NMR data, it can be seen that the target product 4-tert-butoxyacetophenone was synthesized in this embodiment. In this embodiment, the final product yield was 86% and the LC purity was 98.3%.

[0044] Embodiment 2:

[0045] This embodiment provides a method for synthesizing 4-tert-butoxyacetophenone, which comprises the following steps:

[0046] Step 1.1, etherification reaction: add 68g of 4-hydroxyacetophenone, 1.2g of methanesulfonic acid and 200g of dichloroethane to a 500mL autoclave, stir until the solid is dissolved, cool in an ice-water bath, introduce isobutylene gas, maintain the system pressure at 0.15MPa, maintain the system temperature at 20±5°C, react for 6h, take samples for central control, the conversion rate of raw material 4-hydroxyacetophenone is 90.2%, stop the reaction, and obtain a crude product of 4-tert-butoxyacetophenone.

[0047] Step 1.2, post-treatment: In an ice-water bath, add 1.9 g of 30 wt.% sodium hydroxide solution and 20 g of water to the crude product of 4-tert-butoxyacetophenone, adjust the pH to 11, control the internal temperature to 20±2°C, stir thoroughly for 30 min, re-measure the pH if it remains unchanged, let stand to separate, extract the aqueous phase once with 20 g of dichloromethane, combine the organic phases, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, and distill the filtrate under reduced pressure. The resulting solid slurry is slurried with 200 g of petroleum ether and filtered to obtain 74.8 g of a white solid product.

[0048] Product identification: The white solid product was identified by nuclear magnetic resonance spectroscopy, and the result was the same as that in Example 1. From the nuclear magnetic resonance data, it can be seen that the target product 4-tert-butoxyacetophenone was synthesized in this example. In this example, the final product yield was 78% and the LC purity was 98.1%.

[0049] Embodiment 3:

[0050] This embodiment provides a method for synthesizing 4-tert-butoxyacetophenone, which comprises the following steps:

[0051] Step 1.1, etherification reaction: add 68g of 4-hydroxyacetophenone, 0.8g of trifluoromethanesulfonic acid and 200g of dichloroethane to a 500mL autoclave, stir until the solid is dissolved, cool in an ice-water bath, introduce isobutylene gas, maintain the system pressure at 0.3MPa, maintain the system temperature at 20±5°C, react for 5h, take samples for central control, the conversion rate of raw material 4-hydroxyacetophenone is 93.4%, stop the reaction, and obtain a crude product of 4-tert-butoxyacetophenone.

[0052] Step 1.2, post-treatment: In an ice-water bath, add 0.9 g of 30 wt.% sodium hydroxide solution and 20 g of water to the crude product of 4-tert-butoxyacetophenone, adjust the pH to 11, control the internal temperature to 20 ± 2 ° C, stir thoroughly for 30 min, re-measure the pH unchanged, stand and separate, extract the aqueous phase once with 20 g of dichloromethane, combine the organic phases, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, and distill the filtrate under reduced pressure. The resulting solid slurry is slurried with 200 g of petroleum ether and filtered to obtain 84.6 g of a white solid product.

[0053] Product identification: The white solid product was identified by nuclear magnetic resonance spectroscopy, and the result was the same as that in Example 1. From the nuclear magnetic resonance data, it can be seen that the target product 4-tert-butoxyacetophenone was synthesized in this example. In this example, the final product yield was 88% and the LC purity was 98.3%.

[0054] Embodiment 4:

[0055] This embodiment provides a method for synthesizing 4-tert-butoxyphenyl methyl alcohol, which uses 4-tert-butoxyacetophenone prepared in Examples 1 to 3, and comprises the following steps:

[0056] Step 2.1, hydrogenation reaction: add 96 g of 4-tert-butoxyacetophenone, 3.2 g of phenanthroline-iridium complex Cat 3 and 300 g of methanol into a 500 mL autoclave, replace the system with a hydrogen atmosphere, maintain the system pressure at 0.2 MPa, maintain the system temperature at 60°C, react for 6 hours, take samples for control, and stop the reaction when the conversion rate of the raw material 4-tert-butoxyacetophenone is greater than 99%, to obtain a crude product of 4-tert-butoxystyrene;

[0057] Step 2.2, post-treatment: The crude product of 4-tert-butoxystyrene is distilled under reduced pressure to remove the solvent, 300 g of n-hexane is added to the mother liquor and stirred for 10 min, filtered, the filter cake is rinsed with 30 g of n-hexane, the filtrate is distilled under reduced pressure to remove the solvent, and short-path reduced pressure distillation is performed again to obtain 91.3 g of colorless liquid product.

[0058] Product identification: The white solid product was identified by nuclear magnetic resonance spectroscopy, and the results are as follows: 1H NMR (500MHz, CDCl3) δ7.27-7.19(m,2H),7.00-6.88(m,2H),4.83(q,J=6.4Hz,1H),2.09(s,1H),1.46(d,J=6.4Hz,3H),1.33(s,9H). 13 C NMR (126MHz, CDCl3) δ154.6, 140.7, 126.0, 124.1, 78.4, 70.0, 28.8, 25.0. From the above NMR data, it can be seen that the target product 4-tert-butoxyphenylmethyl alcohol was synthesized in this embodiment. In this embodiment, the final product yield was 94% and the LC purity was 98.5%.

[0059] Embodiment 5:

[0060] This embodiment provides a method for synthesizing 4-tert-butoxyphenyl methyl alcohol, which uses 4-tert-butoxyacetophenone prepared in Examples 1 to 3, and comprises the following steps:

[0061] Step 2.1, hydrogenation reaction: 19 g 4-tert-butoxyacetophenone, 1.1 g phenanthroline-iridium complex Cat 2 and 30 g methanol were added to a 100 mL autoclave, the system was replaced with a hydrogen atmosphere, the system pressure was maintained at 0.2 MPa, the system temperature was maintained at 60° C., the reaction was continued for 6 h, sampling was performed for mid-control, the conversion rate of the raw material 4-tert-butoxyacetophenone was 98.4%, the reaction was stopped, and a crude product of 4-tert-butoxystyrene was obtained;

[0062] Step 2.2, post-treatment: The crude product of 4-tert-butoxystyrene is distilled under reduced pressure to remove the solvent, 30 g of n-hexane is added to the mother liquor and stirred for 10 min, filtered, the filter cake is rinsed with 10 g of n-hexane, the filtrate is distilled under reduced pressure to remove the solvent, and short-range reduced pressure distillation is performed again to obtain 17.5 g of colorless liquid product.

[0063] Product identification: The colorless liquid product was identified by NMR spectroscopy, and the result was the same as that in Example 4. From the NMR data, it can be seen that the target product 4-tert-butoxyphenylmethyl alcohol was synthesized in this example. In this example, the final product yield was 90% and the LC purity was 98.1%.

[0064] In this embodiment, the NMR data of phenanthroline-iridium complex Cat 2 are as follows:

[0065] 1 H NMR (500MHz, D2O) δ7.46 (t, J = 8Hz, 2H), 7.03 (d, J = 7Hz, 2H), 6.42 (d, J = 7Hz, 2H), 1.49 (s, 15H). 13C{1H}NMR(125.8MHz,D2O)δ170.6,156.9,139.3,128.6,116.8,107.4,85.6,9.39.

[0066] Embodiment 6:

[0067] This embodiment provides a method for synthesizing 4-tert-butoxyphenyl methyl alcohol, which uses 4-tert-butoxyacetophenone prepared in Examples 1 to 3, and comprises the following steps:

[0068] Step 2.1, hydrogenation reaction: 19 g 4-tert-butoxyacetophenone, 0.64 g phenanthroline-iridium complex Cat 3 and 15 g methanol / 15 g water mixed solvent were added to a 100 mL autoclave, the system was replaced with a hydrogen atmosphere, the system pressure was maintained at 0.2 MPa, the system temperature was maintained at 60° C., the reaction was continued for 4 h, sampling was performed for mid-control, the conversion rate of the raw material 4-tert-butoxyacetophenone was 99.0%, the reaction was stopped, and a crude product of 4-tert-butoxystyrene was obtained;

[0069] Step 2.2, post-treatment: The crude product of 4-tert-butoxystyrene is distilled under reduced pressure to remove the solvent, 30 g of n-hexane is added to the mother liquor and stirred for 10 min, filtered, the filter cake is rinsed with 10 g of n-hexane, the filtrate is distilled under reduced pressure to remove the solvent, and short-range reduced pressure distillation is performed again to obtain 18 g of colorless liquid product.

[0070] Product identification: The colorless liquid product was identified by NMR spectroscopy, and the result was the same as that in Example 4. From the NMR data, it can be seen that the target product 4-tert-butoxyphenylmethyl alcohol was synthesized in this example. In this example, the final product yield was 93% and the LC purity was 98.2%.

[0071] Embodiment 7:

[0072] This embodiment provides a method for synthesizing 4-tert-butoxystyrene, which uses 4-tert-butoxyphenylmethyl alcohol prepared in Examples 4 to 6, and comprises the following steps:

[0073] Step 3.1, dehydration reaction: 77.7 g of 4-tert-butoxyphenyl methyl alcohol was dissolved in 250 g of dimethyl sulfoxide, 5 mL of 4 M hydrochloric acid dioxane solution was added, and the mixture was reacted at 90° C. for 6 h. The conversion rate of the raw material 4-tert-butoxyphenyl methyl alcohol was 97.6%, and a crude product of 4-tert-butoxystyrene was obtained;

[0074] Step 3.2, post-treatment: add 500 mL of water and 500 mL of ethyl acetate to the crude product of 4-tert-butoxystyrene, stir thoroughly and let stand to separate the layers, back-extract the aqueous phase once with 500 mL of ethyl acetate, combine the organic phases, wash twice with 200 mL of saturated brine, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, distill the filtrate to remove ethyl acetate, add 1.3 g of inhibitor 4-tert-butylcatechol, and purify again by short-range vacuum distillation to obtain 62 g of colorless liquid product.

[0075] Product identification: The above colorless liquid product was identified by nuclear magnetic resonance spectroscopy, and the results are as follows 1 H NMR(500MHz, CDCl3) δ7.31(d,J=8.6Hz,2H),6.94(d,J=8.5Hz,2H),6.68(dd,J=17.6, 10.9Hz, 1H), 5.65 (dd, J=17.6, 1.0Hz, 1H), 5.16 (dd, J=10.9, 1.0Hz, 1H), 1.34 (s, 9H). 13 CNMR (126MHz,CDCl3)δ155.2,136.3,132.8,126.7,124.1,112.5,78.6,28.9. From the above NMR data, it can be seen that the target product 4-tert-butoxystyrene is synthesized in this embodiment. In this embodiment, the final product yield is 88% and the LC purity is 98.8%.

[0076] Embodiment 8:

[0077] This embodiment provides a method for synthesizing 4-tert-butoxystyrene, which uses 4-tert-butoxyphenylmethyl alcohol prepared in Examples 4 to 6, and comprises the following steps:

[0078] Step 3.1, dehydration reaction: 20 g of 4-tert-butoxyphenyl methyl alcohol was dissolved in 60 g of dimethyl sulfoxide, 5.8 g of pyridine hydrochloride was added, and the reaction was carried out at 90° C. for 6 h. The conversion rate of the raw material 4-tert-butoxyphenyl methyl alcohol was 95.7%, and the reaction was stopped to obtain a crude product of 4-tert-butoxystyrene;

[0079] Step 3.2, post-treatment: add 100 mL of water and 100 mL of ethyl acetate to the crude product of 4-tert-butoxystyrene, stir thoroughly and let stand to separate the layers, back-extract the aqueous phase once with 100 mL of ethyl acetate, combine the organic phases, wash twice with 50 mL of saturated brine, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, distill the filtrate to remove ethyl acetate, add 0.6 g of inhibitor 4-tert-butylcatechol, and purify again by short-range vacuum distillation to obtain 15 g of colorless liquid product.

[0080] Product identification: The colorless liquid product was identified by NMR spectroscopy, and the result was the same as that in Example 7. From the NMR data, it can be seen that the target product 4-tert-butoxystyrene was synthesized in this example. In this example, the final product yield was 85% and the LC purity was 98.6%.

[0081] Embodiment 9:

[0082] This embodiment provides a method for synthesizing 4-tert-butoxystyrene, which uses 4-tert-butoxyphenylmethyl alcohol prepared in Examples 4 to 6, and comprises the following steps:

[0083] Step 3.1, dehydration reaction: 20 g of 4-tert-butoxyphenyl methyl alcohol was dissolved in 20 g of N, N-dimethylformamide, 0.95 g of stannous chloride was added, and the reaction was carried out at 100° C. for 8 h. The conversion rate of the raw material 4-tert-butoxyphenyl methyl alcohol was 90.4%, and the reaction was stopped to obtain a crude product of 4-tert-butoxystyrene;

[0084] Step 3.2, post-treatment: add 50 mL of water and 50 mL of ethyl acetate to the crude product of 4-tert-butoxystyrene, stir thoroughly and let stand to separate the layers, back-extract the aqueous phase once with 50 mL of ethyl acetate, combine the organic phases, wash twice with 25 mL of saturated brine, add sodium sulfate and dry for 30 min, filter out the sodium sulfate, distill the filtrate to remove ethyl acetate, add 0.6 g of inhibitor 4-tert-butylcatechol, and purify again by short-range vacuum distillation to obtain 14 g of colorless liquid product.

[0085] Product identification: The colorless liquid product was identified by NMR spectroscopy, and the result was the same as that in Example 7. From the NMR data, it can be seen that the target product 4-tert-butoxystyrene was synthesized in this example. In this example, the final product yield was 80% and the LC purity was 97.7%.

[0086] Comparative Example 1:

[0087] This comparative example provides a method for synthesizing 4-tert-butoxyphenylmethyl alcohol, which is basically the same as Example 4, except that a phenanthroline-iridium complex Cat 1 is used as a hydrogenation catalyst, and the chemical structure of the phenanthroline-iridium complex Cat 1 is shown in Formula I-1:

[0088]

[0089] In this comparative example, the final product yield is 73% and the LC purity is 95%. From the above results, it can be seen that the product yield of this comparative example is lower than that of Example 4.

[0090] Comparative Example 2:

[0091] This comparative example provides a method for synthesizing 4-tert-butoxyphenylmethyl alcohol, which is basically the same as Example 4, except that 5 wt.% of palladium on carbon is used as a hydrogenation catalyst.

[0092] In this comparative example, the final product yield is 37% and the LC purity is 91%. From the above results, it can be seen that the product yield of this comparative example is lower than that of Example 4.

[0093] Comparative Example 3:

[0094] This comparative example provides a method for synthesizing 4-tert-butoxyphenylmethyl alcohol, which is basically the same as Example 4, except that Raney nickel is used as a hydrogenation catalyst.

[0095] In this comparative example, the final product yield is 21% and the LC purity is 90%. From the above results, it can be seen that the product yield of this comparative example is lower than that of Example 4.

Claims

1. A method for synthesizing 4-tert-butoxystyrene, characterized in that: Firstly, 4-tert-butoxyacetophenone is synthesized from 4-hydroxyacetophenone and isobutylene; then, 4-tert-butoxyacetophenone and hydrogen are used as raw materials and phenanthroline-iridium complex is used as a hydrogenation catalyst to synthesize 4-tert-butoxyphenylmethyl alcohol; 4-tert-butoxyphenylmethyl alcohol is dehydrated to generate 4-tert-butoxystyrene; The chemical structure of the phenanthroline-iridium complex is shown in the following formula I: In Formula I: R1 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl; R2 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl; R3 is selected from one of hydroxyl, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C1-C10 alkoxy, substituted or unsubstituted C1-C10 aryl, and substituted or unsubstituted C1-C10 heteroaryl.

2. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 1, characterized in that: The phenanthroline-iridium complex is selected from the phenanthroline-iridium complex Cat 2 shown in Formula I-2 and the phenanthroline-iridium complex Cat 3 shown in Formula I-3:

3. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 1, characterized in that: The molar ratio of the 4-tert-butoxyacetophenone to the hydrogenation catalyst is 1:(0.01-0.05).

4. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 1, characterized in that: The method comprises the following steps: Step 1, synthesis of 4-tert-butoxyacetophenone: Adding 4-hydroxyacetophenone and a first acid catalyst into a first reaction solvent, introducing isobutylene gas, and causing an etherification reaction to generate a crude product of 4-tert-butoxyacetophenone; The first acid catalyst is selected from trifluoromethanesulfonic acid, methanesulfonic acid, sulfuric acid, acetic acid, trifluoroacetic acid; The first reaction solvent is selected from one or more of dichloromethane, dichloroethane, ethyl acetate and tetrahydrofuran; Step 2, synthesis of 4-tert-butoxyphenyl methyl alcohol: The 4-tert-butoxyacetophenone prepared in step 1 is dissolved in a second reaction solvent, and subjected to a hydrogenation reaction under a hydrogen atmosphere to generate a crude product of an intermediate 4-tert-butoxyphenylmethyl alcohol; The second reaction solvent is selected from one or more of methanol, ethanol and water; Step 3, synthesis of 4-tert-butoxystyrene: The 4-tert-butoxyphenylmethyl alcohol prepared in step 2 is dissolved in a third reaction solvent, and dehydrated under the action of a second acid catalyst to generate a crude product of 4-tert-butoxystyrene; The second acid catalyst is selected from dioxane hydrochloride solution, pyridine hydrochloride, stannous chloride, bismuth trifluoromethanesulfonate, and hydrochloric acid; The third reaction solvent is selected from one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and toluene.

5. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 4, characterized in that: In step 1, the reaction temperature of the etherification reaction is 0-40° C., and the reaction time is 4-8 hours.

6. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 4, characterized in that: In step 1, the molar ratio of 4-hydroxyacetophenone to the first acid catalyst is 1:(0.02-0.06).

7. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 4, characterized in that: In step 2, the reaction temperature of the hydrogenation reaction is 30-80° C., and the reaction time is 3-8 hours.

8. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 4, characterized in that: In step 2, the pressure of the hydrogen atmosphere is 0.1-0.8 MPa.

9. The method for synthesizing 4-tert-butoxystyrene as claimed in claim 4, characterized in that: In step 3, the reaction temperature of the dehydration reaction is 80-120° C., and the reaction time is 4-10 hours.

10. The method for synthesizing 4-tert-butoxystyrene according to claim 4, characterized in that: In step 3, the molar ratio of the 4-tert-butoxyphenylmethyl alcohol to the second acid catalyst is 1:(0.01-0.05).

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