Method for preparing sulfonium salt from functional ionic liquid

Abstract

The invention discloses a method for preparing sulfonium salt from functional ionic liquid. The method comprises the following steps: S1, mixing iodobenzene / iodobenzene, benzene / methylbenzene, ionic liquid and trifluoromethanesulfonate / perfluorobutyl sulfonate, and reacting with hydrogen peroxide for 12-24 hours to obtain a mixed solution; and S2, recovering the aromatic hydrocarbon in the mixed solution obtained in the step S1 until no fraction exists, adding phenyl sulfide, heating, reacting for 12-24 hours, and after the reaction is finished, purifying to obtain the triaryl sulfonium salt. The method is simple in process operation and low in equipment requirement, and the functional ionic liquid adopted in the reaction is a green solvent, is non-oxidative, non-combustible and non-volatile, has good stability and can be recycled and reused for multiple times; (methyl) benzene and iodo (methyl) benzene generated in the process reaction and post-treatment process can be recycled and reused, so that the production cost is greatly reduced; the total yield of the target product synthesized by the method can reach 80%, the purity of the product can also reach 99% or above, the three wastes generated in the production process are few, no acid wastewater is generated, the method is environment-friendly, the industrial feasibility is high, the method can be applied to industrial production on a large scale, and the ever-increasing market requirements are met.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, and in particular to a method for preparing sulfonium salts using functional ionic liquids. Background Art

[0002] Aryl sulfonium salt is a commonly used cationic photoinitiator. Compared with free radical photoinitiators, cationic photoinitiators have less oxygen inhibition, can polymerize quickly even in the air, have fast curing speed, low volume shrinkage of the cured coating, low toxicity, good mechanical properties, etc. At present, the cost of preparing aryl sulfonium salts is relatively high, and more "three wastes" are generated during the production process;

[0003] In 2004, Imazeki.S et al. published a method for preparing sulfonium salts in the paper "Facile method for the preparation of triarylsulfonium bromides using grignard reagents and chlorotrimethylsilaneas an activator". This method uses dichlorothionyl and aryl Grignard reagents as raw materials, trimethylsilane chloride as an activator, and generates arylsulfonium salts under acidic conditions. However, this method uses Grignard reagents and requires a reaction environment that is free of water and oxygen, which is very restrictive and cannot be industrialized.

[0004] In 2014, Yoo.BJ et al. published a method for preparing sulfonium salt in the paper "Triphenylsulfonium salt methacrylate bound polymer resist for electron beam lithography". This method uses diphenyl sulfoxide, trifluoromethylsulfonic anhydride and toluene as raw materials to generate aromatic sulfonium salt under low temperature conditions of -78°C. However, this method uses an ultra-low temperature environment and has many limitations. In addition, this method produces isomers, which makes it difficult to purify the product and cannot be industrialized.

[0005] In 2022, Takenaga Naoko et al. published a method for preparing sulfonium salts in the paper "Catalytic and non-catalytic selectivearyl transfer from (mesityl)iodonium(Ⅲ)salts to diarylsulfide compounds". This method uses benzene sulfide, iodonium salt, and copper trifluoromethanesulfonate as raw materials to generate aromatic sulfonium salts. However, this method introduces heavy metal ion copper during the reaction process, and the use of the highly toxic 1.2-dichloroethane as a solvent will adversely affect the product quality. Summary of the invention

[0006] The invention provides a method for preparing sulfonium salts by using a novel functional ionic liquid, which solves the disadvantages of high cost, high solvent toxicity and pollution in the traditional method.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A method for preparing sulfonium salts from functional ionic liquids comprises the following steps:

[0009] S1: mixing iodobenzene / iodotoluene, benzene / toluene, ionic liquid, trifluoromethanesulfonate / perfluorobutylsulfonate and reacting with hydrogen peroxide for 12-24 hours to obtain a mixed solution;

[0010] S2, recovering benzene / toluene in the mixed solution obtained in step S1 until there is no fraction, adding diphenyl sulfide, heating and reacting for 12-24 hours, and after the reaction is completed, purifying to obtain triarylsulfonium salt.

[0011] Furthermore, the iodobenzene is iodobenzene, and the iodotoluene is one of 2-iodotoluene, 3-iodotoluene and 4-iodotoluene.

[0012] Furthermore, the ionic liquid is at least one of an imidazole ionic liquid, a pyridine ionic liquid, and a quaternary ammonium ionic liquid.

[0013] Furthermore, the molar ratio of iodobenzene / iodotoluene, benzene / toluene, hydrogen peroxide, trifluoromethanesulfonate / perfluorobutylsulfonate and phenylene sulfide is 1:(3-5):(3-5):(1.05-2):(1.0-1.5).

[0014] Furthermore, the concentration of the hydrogen peroxide is 50-90%.

[0015] Furthermore, in S1, the reaction temperature is 0-40°C; in S2, the reaction temperature is 80-160°C.

[0016] Furthermore, in S1, the trifluoromethanesulfonate is at least one of potassium trifluoromethanesulfonate and sodium trifluoromethanesulfonate, and the perfluorobutylsulfonate is at least one of sodium perfluorobutylsulfonate and potassium perfluorobutylsulfonate.

[0017] The beneficial effects of the present invention are:

[0018] 1. The method for preparing sulfonium salts from functional ionic liquids disclosed in the present invention has simple process operation and low equipment requirements. The functional ionic liquid used in the reaction is a green solvent that is non-oxidizing, non-combustible, non-volatile, has good stability and can be recycled and reused multiple times. The (methyl)benzene and iodo (methyl)benzene produced during the process reaction and post-treatment can be recycled and reused, which greatly reduces the production cost;

[0019] 2. The total yield of the target product synthesized by this method can reach 80%, and the purity of the product can reach more than 99%. The "three wastes" generated in the production process are small, and no acidic wastewater is generated. It is environmentally friendly and has high industrial feasibility. It can be used on a large scale in industrial production to meet the growing market demand. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 The triphenylsulfonium trifluoromethanesulfonate prepared in Example 1 of the present invention 1 H-NMR spectrum;

[0022] Figure 2 The triphenylsulfonium trifluoromethanesulfonate prepared in Example 1 of the present invention 19 F-NMR spectrum;

[0023] Figure 3 The diphenyl (4-methylphenyl) sulfonium trifluoromethyl sulfonate prepared in Example 2 of the present invention 1 H-NMR spectrum;

[0024] Figure 4 The triphenylsulfonium perfluorobutyl sulfonate prepared in Example 3 of the present invention 19 F-NMR nuclear magnetic spectrum. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The reaction formula involved in the present invention is as follows:

[0027]

[0028] Examples of related structures of imidazole ionic liquids, pyridine ionic liquids, and quaternary ammonium ionic liquids (including but not limited to):

[0029]

[0030] Example 1: Preparation of triphenylsulfonium trifluoromethanesulfonate

[0031] Weigh 27.3 g of benzene, 20.4 g of iodobenzene, 60 g of imidazole ionic liquid, and 19.7 g of potassium trifluoromethanesulfonate, mix them and heat them to 40 ° C. and stir them evenly. Add 15.84 g of 75% H2O2 aqueous solution dropwise, keep warm at 40 ° C. for 12 h, then take samples for GC detection and analysis until the iodobenzene content is <0.5%. After reducing pressure and recovering excess benzene until there is no fraction, add 22.8 g of phenylene sulfide, keep warm at 120 ° C. for 16 h, then take samples for HPLC detection and analysis until the intermediate iodonium salt content is <0.5%, cool to 50 ° C, add 100 g of water, stir for 1.0 h, filter, wash the filter cake once with 50 g of 50 ° C water, dry, and crystallize the crude product with ethyl acetate / n-hexane 1:2 to obtain 33.5 g of white solid triphenylsulfonium trifluoromethanesulfonate, content: 99.2%, yield: 80%, melting point 134-135 ° C. Ionic liquids can be used multiple times after being processed.

[0032] The white solid obtained above was 1 H-NMR and 19 F-NMR nuclear magnetic analysis, the results are as follows Figure 1 As shown, the NMR data is 1 H-NMR (400MHZ,CDCl3)7.66-7.78 (m,15H), such as Figure 2 As shown, the NMR data is 19 F-NMR (376MHZ,CDCl3):δ-78.1.

[0033] Example 2 Preparation of diphenyl (4-methylphenyl) sulfonium trifluoromethanesulfonate

[0034] Weigh 32.2g of toluene, 21.8g of p-iodotoluene, 60g of quaternary ammonium salt ionic liquid, and 19.7g of potassium trifluoromethanesulfonate, mix them and heat them to 40°C and stir them evenly. Add 15.84g of 75% H2O2 aqueous solution dropwise, keep warm at 40°C for reaction for 12h, take samples for GC detection and analysis until the p-iodotoluene content is <0.5%, recover the excess toluene under reduced pressure until there is no fraction, add 22.8g of phenyl sulfide, keep warm at 100°C for reaction for 12h, take samples for HPLC detection and analysis until the intermediate iodonium salt content is <0.5%, cool to 50°C, add 100g of water, stir for 1.0h, filter, wash the filter cake once with 50g of 50°C water, dry, and crystallize the crude product with ethyl acetate / n-hexane 1:2 to obtain 31.9g of diphenyl (4-methylphenyl) sulfonium trifluoromethanesulfonate as a white solid, with a content of 99.2%, a yield of 75%, and a melting point of 100-102°C.

[0035] The white solid obtained above was1 H-NMR analysis, the results are as follows Figure 3 As shown, the NMR data is 1 H-NMR(400MHZ, CDCl3)2.44(s,3H),7.47-7.49(d,2H),7.57-7.59(d,2H),7.64-7.04(m,8H),7.15-7.37(m,2H).

[0036] Example 3: Preparation of triphenylsulfonium perfluorobutanesulfonate

[0037] Weigh 27.3 g of benzene, 20.4 g of iodobenzene, 60 g of pyridine ionic liquid, and 35.5 g of potassium perfluorobutanesulfonate, mix them and heat them to 40 ° C. and stir them evenly. Add 13.2 g of 90% H2O2 aqueous solution dropwise, keep the temperature at 40 ° C. for reaction for 12 h, then take a sample for GC detection and analysis until the iodobenzene content is <0.5%. After reducing the pressure to recover the excess benzene until there is no fraction, add 24.2 g of phenylene sulfide, keep the temperature at 120 ° C. for reaction for 16 h, then take a sample for HPLC detection and analysis until the intermediate iodonium salt content is <0.5%, cool to 50 ° C, add 100 g of toluene, stir for 1.0 h, filter, wash the filter cake once with 50 g of 50 ° C water, dry, and crystallize the crude product with ethyl acetate / n-hexane 1:2 to obtain 45.9 g of white solid triphenylsulfonium perfluorobutanesulfonate, content: 99.1%, yield: 81%, melting point 85-86 ° C.

[0038] The white solid obtained above was 19 F-NMR analysis, the results are as follows Figure 4 As shown, the NMR data is 19 F-NMR (376MHZ, CDCl3): δ-80.9, δ-114.5, δ-121.5, δ-125.9.

[0039] Example 4: Preparation of diphenyl (4-methylphenyl) sulfonium perfluorobutane sulfonate

[0040] Weigh 32.2 g of toluene, 21.8 g of p-iodotoluene, 60 g of quaternary ammonium salt ionic liquid, and 35.5 g of potassium perfluorobutanesulfonate, mix them and heat them to 40 ° C. and stir them evenly. Add 15.84 g of 75% H2O2 aqueous solution dropwise, keep the mixture at 40 ° C. for reaction for 12 h, then take a sample and perform GC detection and analysis until the p-iodotoluene content is <0.5%. After the excess toluene is recovered under reduced pressure until there is no fraction, 22.8 g of phenyl sulfide is added, and the mixture is kept at 100 ° C. for reaction for 12 h, then take a sample and perform HPLC detection and analysis until the intermediate iodonium salt content is <0.5%. Cool to 50 ° C., add 100 g of toluene, stir for 1.0 h, and stand for separation. The lower layer of the liquid is purified by column chromatography with ethyl acetate / n-hexane 1:2 to obtain 45.6 g of light yellow liquid diphenyl (4-methylphenyl) sulfonium perfluorobutanesulfonate, with a content of 98.5% and a yield of 77%.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing sulfonium salts from functional ionic liquids, characterized in that: The steps include: S1: mixing iodobenzene / iodotoluene, benzene / toluene, ionic liquid, trifluoromethanesulfonate / perfluorobutylsulfonate and reacting with hydrogen peroxide for 12-24 hours to obtain a mixed solution; S2, recovering benzene / toluene in the mixed solution obtained in step S1 until there is no fraction, adding diphenyl sulfide, heating and reacting for 12-24 hours, and after the reaction is completed, purifying to obtain triarylsulfonium salt.

2. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: In step S1, the iodobenzene is iodobenzene, and the iodotoluene is one of 2-iodotoluene, 3-iodotoluene and 4-iodotoluene.

3. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: The ionic liquid is at least one of an imidazole ionic liquid, a pyridine ionic liquid, and a quaternary ammonium ionic liquid.

4. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: The molar ratio of iodobenzene / iodotoluene, benzene / toluene, hydrogen peroxide, trifluoromethanesulfonate / perfluorobutylsulfonate and phenylene sulfide is 1:(3-5):(3-5):(1.05-2):(1.0-1.5).

5. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: The concentration of the hydrogen peroxide is 50-90%.

6. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: In S1, the reaction temperature is 0-40°C; in S2, the reaction temperature is 80-160°C.

7. The method for preparing sulfonium salt from functional ionic liquid according to claim 1, characterized in that: In S1, the trifluoromethanesulfonate is at least one of potassium trifluoromethanesulfonate and sodium trifluoromethanesulfonate, and the perfluorobutylsulfonate is at least one of sodium perfluorobutylsulfonate and potassium perfluorobutylsulfonate.

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