Method for preparing p-(1-ethoxyethoxy) styrene

Abstract

The invention discloses a method for preparing p-(1-ethoxyethoxy) styrene, and belongs to the technical field of organic compound preparation. The method comprises the following steps: reacting p-hydroxystyrene with vinyl ethyl ether in an organic solvent under the catalysis of a catalyst to generate p-(1-ethoxyethoxy) styrene; the catalyst is a composite catalyst containing a sulfonic acid pyridine salt catalyst and a phase transfer catalyst. Compared with the prior art, the method has the advantages that the compound catalyst containing the faintly acid pyridine sulfonate catalyst and the phase transfer catalyst is used for replacing the pyridine sulfonate catalyst in the prior art, so that lower reaction cost, shorter reaction time, higher yield and higher purity can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of organic compound preparation, and in particular to a method for preparing p-(1-ethoxyethoxy)styrene. Background Art

[0002] p-(1-ethoxyethoxy)styrene is a commonly used raw material in the field of photoresists. The commonly used synthesis route is as follows: p-hydroxystyrene and ethyl vinyl ether are used as raw materials to react under the action of p-toluenesulfonic acid to produce 1-(1-ethoxyethoxy)-4-vinylbenzene. This synthesis method has many by-products, low purity, low yield, difficult operation in industrial application, high cost, low safety, and easy polymerization during the reaction.

[0003] Chinese patent application CN115974659A discloses a method for synthesizing 1-(1-ethoxyethoxy)-4-vinylbenzene. Specifically, the method comprises adding p-hydroxystyrene, a sulfonic acid pyridinium salt catalyst and a first inhibitor to an organic solution A, and then adding ethyl vinyl ether to carry out acetalization reaction to obtain a reaction solution; then purifying the reaction solution to obtain 1-(1-ethoxyethoxy)-4-vinylbenzene; the sulfonic acid pyridinium salt catalyst is selected from at least one of p-toluenesulfonic acid pyridinium salt, trifluoromethanesulfonic acid pyridinium salt or methanesulfonic acid pyridinium salt; and the first inhibitor is selected from phenothiazine, p-hydroxyanisole or p-methoxyphenol. The method also includes a purification step: a1) concentrating and removing the organic solution A in the reaction solution, and adding an organic solvent B; a2) washing the solution obtained in step a1) with an aqueous NaOH solution or a KOH solution; a3) washing the solution obtained in step a2) with a saturated NaCl solution or a saturated KCl solution, separating and removing the aqueous phase, drying, adding a second inhibitor, and distilling under reduced pressure to obtain 1-(1-ethoxyethoxy)-4-vinylbenzene; the second inhibitor is selected from phenothiazine, p-hydroxyanisole or p-methoxyphenol. The synthesis method uses a sulfonic acid pyridinium salt catalyst with weaker acidity and milder properties to replace the p-toluenesulfonic acid catalyst with stronger acidity, thereby improving the stability of the product 1-(1-ethoxyethoxy)-4-vinylbenzene, which contains an acid-labile group, i.e., an acetal structure, and is easily hydrolyzed in an acidic environment. The synthesis method also requires the addition of an inhibitor to prevent the raw materials and products containing unsaturated bonds from being unstable and polymerizing during the reaction. The patent's Examples 2 and 3 show that the yields of 1-(1-ethoxyethoxy)-4-vinylbenzene are 85% and 83% respectively when the reaction is carried out overnight at 25°C using pyridinium p-toluenesulfonate as a catalyst and phenothiazine or p-hydroxyanisole as an inhibitor. The above method for preparing 1-(1-ethoxyethoxy)-4-vinylbenzene has the disadvantages of being unfavorable for industrial large-scale preparation, including: requiring a long reaction time, high cost, and the yield still needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems existing in the prior art and provide a method for preparing p-(1-ethoxyethoxy)styrene. The present invention uses a composite catalyst comprising a weakly acidic pyridinium sulfonate catalyst and a phase transfer catalyst to replace the pyridinium sulfonate catalyst in the prior art, and compared with the prior art, lower reaction cost, shorter reaction time, higher yield, higher purity, etc. can be achieved.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] A method for preparing p-(1-ethoxyethoxy)styrene comprises the following steps: reacting p-hydroxystyrene with vinyl ethyl ether in an organic solvent under the catalysis of a catalyst to produce p-(1-ethoxyethoxy)styrene; the catalyst is a composite catalyst comprising at least a sulfonate pyridinium salt catalyst and a phase transfer catalyst; preferably, the catalyst is a composite catalyst consisting of a sulfonate pyridinium salt catalyst and a phase transfer catalyst.

[0007] In some embodiments, the sulfonate pyridinium salt catalyst is selected from any one or any combination of pyridinium p-toluenesulfonate, pyridinium trifluoromethanesulfonate, and pyridinium methanesulfonate.

[0008] In some embodiments, the phase transfer catalyst is selected from any one of polyethers, cyclic crown ethers, quaternary ammonium salts, tertiary amines, quaternary ammonium bases, and quaternary phosphonium salts.

[0009] In some embodiments, the polyether is selected from polyethylene glycol or polyethylene glycol dialkyl ether.

[0010] In some embodiments, the cyclic crown ether is selected from any one of 18-crown-6, 15-crown-5, and cyclodextrin.

[0011] In some embodiments, the quaternary ammonium salt is selected from tetrabutylammonium bromide or tetrabutylammonium hydrogen sulfate.

[0012] In some embodiments, the tertiary amine is selected from pyridine or tributylamine.

[0013] In some embodiments, the organic solvent is ethyl acetate.

[0014] In some embodiments, the weight ratio of the p-hydroxystyrene to the vinyl ethyl ether is 1:2-1:4, and the range between any two of the above values ​​can also be selected, for example; the weight ratio is 1:2-1:3, 1:3-1:4. In a specific embodiment, the weight ratio of the p-hydroxystyrene to the vinyl ethyl ether can be selected as 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc.; the amount of the catalyst used is 1-2% of the weight of the p-hydroxystyrene. In a specific embodiment, the amount of the catalyst used is It can be selected as 1%, 1.5%, 2% and the like of the weight of the p-hydroxystyrene; the molar ratio of the sulfonate pyridinium salt catalyst to the phase transfer catalyst in the composite catalyst is 1:0.5-1:3, and a range between any two of the aforementioned values ​​can also be selected, for example; the molar ratio is 1:0.5-1:1, 1:1-1:2, 1:2-1:3. In a specific embodiment, the molar ratio of the sulfonate pyridinium salt catalyst to the phase transfer catalyst in the composite catalyst can be selected as 1:0.5, 1:1, 1:2, 1:3 and the like.

[0015] In some embodiments, the reaction temperature is 20-30° C., and the reaction time is 4-7 hours.

[0016] The beneficial effects of the present invention are as follows:

[0017] The present invention uses a composite catalyst comprising a weakly acidic sulfonic acid pyridinium salt catalyst and a phase transfer catalyst to replace the sulfonic acid pyridinium salt catalyst in the prior art. Compared with the prior art which requires overnight reaction at 25° C., the reaction time of the present invention is significantly shortened to only 4-7 hours, and the yield is higher. According to experiments, the sulfonic acid pyridinium salt catalyst p-toluenesulfonic acid pyridinium salt and the phase transfer catalyst 18-crown ether-6 are combined as the composite catalyst, and the yield of the target product can reach 92.8%.

[0018] The invention develops a high-yield reaction process for p-(1-ethoxyethoxy)styrene by adjusting a series of reaction elements such as the amount of catalyst used (feeding amount), reaction temperature, reaction time, raw material feeding ratio, composition of the composite catalyst, etc. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments.

[0020] Examples 1-3

[0021] The raw materials involved in this embodiment are p-hydroxystyrene and vinyl ethyl ether, the proportions are shown in Table 1, the catalyst used is shown in Table 2, and the organic solvent is ethyl acetate. The reaction formula is as follows:

[0022]

[0023] Reaction steps: Under the conditions of 25°C and normal pressure, 15g of p-hydroxystyrene (industrial pure) is dissolved in 30mL of ethyl acetate (industrial pure), added to a 200mL three-necked flask, then 45g of vinyl ethyl ether (industrial pure), and finally 0.225g of catalyst is added, and then stirred continuously at 100-200rpm. After reacting for 5h, the reaction solution is added to a 1L separatory funnel, washed with pure water 8 times, the upper organic layer is taken for GC measurement, the amount of the product is detected, and after separating the lower layer of water, the crude p-(1-ethoxyethoxy) styrene is concentrated by rotary evaporation at 40°C to obtain the crude p-(1-ethoxyethoxy) styrene, and then enters the first molecular distillation to remove the residual water and other small molecules. The oil phase after removing the small molecules is transported to the second molecular distillation, and the product p-(1-ethoxyethoxy) styrene is treated as a small molecule component, distilled and condensed into a small molecule collection tube, and the distilled product is pure p-(1-ethoxyethoxy) styrene, with a yield of 92.8% and a purity of 99.5%.

[0024] Table 1

[0025] Molecular weight (g / mol) Weight(g) p-Hydroxystyrene 120.15 15 Ethyl vinyl ether 72.11 45 catalyst 515.62 0.225

[0026] Table 2

[0027] catalyst Yield (%) Example 1 Pyridinium p-toluenesulfonate + 18-crown ether-6 (phase transfer catalyst) 92.8 Example 2 Pyridinium p-toluenesulfonate + polyethylene glycol (phase transfer catalyst) 76.3 Example 3 Pyridinium p-toluenesulfonate + Tetrabutylammonium bromide (phase transfer catalyst) 83.0 Comparative Example 1 Pyridinium p-toluenesulfonate 73.5 Comparative Example 2 18-Crown ether-6(phase transfer catalyst) 52.9 Comparative Example 3 Polyethylene glycol (phase transfer catalyst) 45.4 Comparative Example 4 Tetrabutylammonium bromide (phase transfer catalyst) 48.0

[0028] Note: In Table 2, the molar ratio of pyridinium p-toluenesulfonate to 18-crown ether-6 in Example 1, the molar ratio of pyridinium p-toluenesulfonate to polyethylene glycol in Example 2, and the molar ratio of pyridinium p-toluenesulfonate to tetrabutylammonium bromide in Example 3 are all 1:1. The examples and comparative examples in Table 2 differ only in the catalyst, and the other reaction conditions are the same.

[0029] The present embodiment investigates the impact of preparing p-(1-ethoxyethoxy) styrene reaction yield by using phase-transfer catalyst and p-toluenesulfonic acid pyridinium salt to be compounded into composite catalyst.Wherein, the phase-transfer catalyst used in embodiment 1 is cyclic crown ether, the phase-transfer catalyst used in embodiment 2 is polyether, and the phase-transfer catalyst used in embodiment 3 is quaternary ammonium salt.As shown in the results of table 2, compared with using p-toluenesulfonic acid pyridinium salt as catalyst alone, after compounding phase-transfer catalyst 18-crown ether-6 and tetrabutylammonium bromide as composite catalyst, yield is significantly improved, and after compounding phase-transfer catalyst polyethylene glycol as composite catalyst, yield improvement is not obvious.Meanwhile, as can be seen from the data comparison of comparative example 2-4, using phase-transfer catalyst alone as catalyst, yield is relatively low.It can be seen that p-toluenesulfonic acid pyridinium salt and phase-transfer catalyst can cooperate with each other, so as to effectively improve the yield of p-(1-ethoxyethoxy) styrene.

[0030] Among the three phase transfer catalysts in Examples 1-3, the cyclic crown ether phase transfer catalyst 18-crown ether-6 in Example 1 achieved the highest yield of the target product, which was significantly higher than the quaternary ammonium salt phase transfer catalyst tetrabutylammonium bromide in Example 3, while the polyether phase transfer catalyst polyethylene glycol in Example 2 did not achieve good improvement.

[0031] Embodiment 4-5

[0032] Based on Example 1, this example further investigates the effect of using equimolar amounts of different cyclic crown ether transfer catalysts (15-crown ether-5, cyclodextrin) on the yield of the p-(1-ethoxyethoxy)styrene preparation reaction. Except for the catalyst type, the other reaction conditions are the same as those in Example 1. The results are shown in Table 3.

[0033] Table 3

[0034] catalyst Yield (%) Example 1 Pyridinium p-toluenesulfonate + 18-crown ether-6 (phase transfer catalyst) 92.8 Example 4 Pyridinium p-toluenesulfonate + 15-crown ether-5 (phase transfer catalyst) 86.1 Example 5 Pyridinium p-toluenesulfonate + cyclodextrin (phase transfer catalyst) 82.3

[0035] As shown in the results in Table 3, after pyridinium p-toluenesulfonate was compounded with 18-crown-6, 15-crown-5 and cyclodextrin to form a composite catalyst, a higher yield of the target product was achieved than when pyridinium p-toluenesulfonate was used as a catalyst, and 18-crown-6 was the most outstanding, with a yield of p-(1-ethoxyethoxy)styrene as high as 92.8%.

[0036] Embodiment 6-8

[0037] Based on Example 1, this example further investigates the effect of using different molar amounts of 18-crown ether-6 on the yield of the p-(1-ethoxyethoxy)styrene preparation reaction. Except for the different catalyst feed amounts, other reaction conditions are the same as in Example 1. The results are shown in Table 4.

[0038] Table 4

[0039] catalyst Molar Ratio Yield (%) Example 6 Pyridinium p-toluenesulfonate: 18-crown-6 1：0.5 83.0 Example 1 Pyridinium p-toluenesulfonate: 18-crown-6 1：1 92.8 Example 7 Pyridinium p-toluenesulfonate: 18-crown-6 1：2 92.9 Example 8 Pyridinium p-toluenesulfonate: 18-crown-6 1：3 92.7

[0040] As shown in the results in Table 4, as the amount of 18-crown-6 in the composite catalyst increased, the reaction yield did not increase further. When the molar ratio of pyridinium p-toluenesulfonate to 18-crown-6 was 1:1, the yield basically reached a plateau.

[0041] Examples 9-12

[0042] Based on Example 1, this example further investigates the effect of different reaction temperatures on the yield of p-(1-ethoxyethoxy)styrene preparation. Except for the different reaction temperatures, other reaction conditions are the same as those in Example 1. The results are shown in Table 5.

[0043] Table 5

[0044] Reaction temperature Yield (%) Example 9 15℃ 81.1 Example 10 20℃ 86.6 Example 1 25℃ 92.8 Embodiment 11 30℃ 92.9 Example 12 35℃ 92.8

[0045] As shown in the results of Table 5, p-(1-ethoxyethoxy)styrene basically reaches the highest yield when the reaction temperature is 25°C. When the temperature is lower than 25°C, the reaction is incomplete and the yield decreases. When the temperature is higher than 25°C, the yield does not increase substantially.

[0046] Examples 13-16

[0047] Based on Example 1, this example further investigates the effect of different reaction times on the yield of p-(1-ethoxyethoxy)styrene preparation. Except for the different reaction times, other reaction conditions are the same as those in Example 1. The results are shown in Table 6.

[0048] Table 6

[0049] Response time (hours) Yield (%) Embodiment 13 3 89.3 Embodiment 14 4 90.2 Example 1 5 92.8 Embodiment 15 6 92.8 Example 16 7 92.9

[0050] As shown in the results of Table 6, when the reaction time was shortened from 5 hours to 4 hours, the yield decreased, and when it was extended to more than 5 hours, the yield remained basically unchanged, indicating that the reaction had basically reached the reaction endpoint at 5 hours.

[0051] Examples 17-21

[0052] Based on Example 1, this example further investigates the effect of different weight ratios of p-hydroxystyrene to vinyl ethyl ether on the yield of p-(1-ethoxyethoxy)styrene preparation. Except for the weight ratio of the raw material feed, other reaction conditions are the same as those in Example 1. The results are shown in Table 7.

[0053] Table 7

[0054] Weight ratio of raw material input amount of p-hydroxystyrene and vinyl ethyl ether Yield (%) Embodiment 17 1：1.5 72.2 Embodiment 18 1：2 85.1 Embodiment 19 1：2.5 87.5 Example 1 1：3 92.8 Embodiment 20 1：3.5 92.9 Embodiment 21 1：4 92.8

[0055] As shown in the results of Table 7, too little vinyl ether feeding will lead to incomplete reaction and decreased yield. When the weight ratio of p-hydroxystyrene to the vinyl ether is 1:3, the yield increase basically reaches a plateau, and further increasing the vinyl ether does not significantly increase the yield of p-(1-ethoxyethoxy)styrene.

[0056] Examples 22-24

[0057] Based on Example 1, this example further investigates the effect of different feed amounts of catalyst (molar ratio of p-toluenesulfonic acid pyridinium salt: 18-crown ether-6 = 1:1) on the yield of p-(1-ethoxyethoxy)styrene preparation reaction. Except for the different feed amounts of catalyst, other reaction conditions are the same as those in Example 1. The results are shown in Table 8.

[0058] Table 8

[0059] The amount of catalyst added is the weight percentage of p-hydroxystyrene (%) Yield (%) Embodiment 22 0.5 73.6 Embodiment 23 1 85.0 Example 1 1.5 92.8 Embodiment 24 2 92.8

[0060] As shown in the results of Table 8, when a composite catalyst with a molar ratio of pyridinium p-toluenesulfonate:18-crown ether-6=1:1 is used as a catalyst, the yield reaches the highest when the amount of catalyst added is 1.5% of the weight of p-hydroxystyrene. When the amount of catalyst added is less than 1.5%, the yield decreases, and when the amount of catalyst added is more than 1.5%, the yield no longer increases.

[0061] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the definition of the claims.

Claims

1. A method for preparing p-(1-ethoxyethoxy)styrene, characterized in that: The method comprises the following steps: reacting p-hydroxystyrene with vinyl ethyl ether in an organic solvent under the catalysis of a catalyst to produce p-(1-ethoxyethoxy)styrene; the catalyst is a composite catalyst comprising at least a sulfonic acid pyridinium salt catalyst and a phase transfer catalyst.

2. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 1, characterized in that: The sulfonate pyridinium salt catalyst is selected from any one or any combination of p-toluenesulfonate pyridinium salt, trifluoromethanesulfonate pyridinium salt, and methanesulfonate pyridinium salt.

3. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 1, characterized in that: The phase transfer catalyst is selected from any one of polyether, cyclic crown ether, quaternary ammonium salt, tertiary amine, quaternary ammonium base and quaternary phosphonium salt.

4. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 3, characterized in that: The polyether is selected from polyethylene glycol or polyethylene glycol dialkyl ether.

5. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 3, characterized in that: The cyclic crown ether is selected from any one of 18-crown ether-6, 15-crown ether-5 and cyclodextrin.

6. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 3, characterized in that: The quaternary ammonium salt is selected from tetrabutylammonium bromide or tetrabutylammonium hydrogen sulfate.

7. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 3, characterized in that: The tertiary amine is selected from pyridine or tributylamine.

8. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 1, characterized in that: The organic solvent is ethyl acetate.

9. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 1, characterized in that: The weight ratio of the p-hydroxystyrene to the vinyl ethyl ether is 1:2-1:4; the amount of the catalyst used is 1-2% of the weight of the p-hydroxystyrene; the molar ratio of the sulfonic acid pyridinium salt catalyst to the phase transfer catalyst in the composite catalyst is 1:0.5-1:

3.

10. A method for preparing p-(1-ethoxyethoxy)styrene according to claim 1, characterized in that: The reaction temperature is 20-30° C., and the reaction time is 4-7 hours.

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