Thioxanthone photoinitiator intermediate, preparation method of thioxanthone photoinitiator intermediate, water-based polymerizable thioxanthone photoinitiator and preparation method of water-based polymerizable thioxanthone photoinitiator

Abstract

The invention discloses a thioxanthone photoinitiator intermediate and a preparation method thereof, and the molecular structure of the thioxanthone photoinitiator intermediate is shown as a formula I-6. The invention also discloses a water-based polymerizable thioxanthone photoinitiator prepared from the thioxanthone photoinitiator intermediate, and the molecular structure of the water-based polymerizable thioxanthone photoinitiator is shown as a formula S, according to the water-based polymerizable thioxanthone photoinitiator, the molecular structure of the photoinitiator is specifically designed, so that the solubility, the photo-initiation efficiency and the safety of the photoinitiator in a water-based system are remarkably improved, and the water-based polymerizable thioxanthone photoinitiator prepared by the preparation method disclosed by the invention has good water solubility and high photo-initiation efficiency; meanwhile, the molecular structure of the water-based polymerizable thioxanthone photoinitiator can be copolymerized with a monomer in a photo-initiation polymerization reaction, so that the water-based polymerizable thioxanthone photoinitiator can be covalently bonded to a main chain of a polymer after being cured, and the migration problem of the photoinitiator is effectively avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of photoinitiators, and specifically relates to a thioxanthone photoinitiator intermediate and a preparation method thereof. The present invention also relates to an aqueous polymerizable thioxanthone photoinitiator prepared by using the thioxanthone photoinitiator intermediate and a preparation method thereof. Background Art

[0002] Photoinitiators are important compounds in the field of photochemistry. They can absorb photon energy under ultraviolet or visible light, initiate polymerization reactions through free radical or cationic mechanisms, and achieve rapid curing of materials such as coatings, inks, and adhesives. Photocurable materials have the advantages of fast curing speed, low energy consumption, and less environmental pollution, and are widely used in industrial coatings, 3D printing, and biomedical materials.

[0003] With the increasingly stringent environmental regulations and people's demand for sustainable development, the application of water-based photocurable materials has received increasing attention. However, most traditional photoinitiators are oily systems, insoluble in water, and easy to migrate, which seriously affects the environmental protection of the materials and the safety of the final application. Therefore, the development of photoinitiators with good water solubility, polymerizability and no migration is an important research direction in the current photochemical field.

[0004] Thioxanthone compounds are widely used in the design of photoinitiators because of their high molar extinction coefficient, strong light absorption ability and good photochemical activity. However, traditional thioxanthone photoinitiators still have the following shortcomings:

[0005] 1. Poor water solubility: Most of the existing thioxanthone photoinitiators have poor solubility in aqueous systems due to the lack of water-soluble groups, which limits their application in environmentally friendly water-based photocuring systems.

[0006] 2. Low initiation efficiency: Traditional thioxanthone photoinitiators have low photoinitiation efficiency in aqueous systems and slow polymerization reaction rates, which makes it difficult to meet the needs of industrial applications.

[0007] 3. Environmental unfriendliness and migration: After the polymerization reaction, the traditional thioxanthone photoinitiator is easy to migrate in the curing material because its chemical structure is not covalently bonded to the polymer main chain. For example, the patent document with the announcement number CN107400112B discloses a photoinitiator and its preparation method. The photoinitiator realizes long-wave absorption based on the thioxanthone parent core and has strong absorption of 395nm UV LED light source. The photoinitiator is endowed with low surface tension by introducing fluorocarbon chains, so that the photoinitiator can float to the surface of the coating / ink layer in the formulation system, that is, the photoinitiator can be enriched on the surface, and a high concentration of free radicals is generated on the surface after absorbing light to resist surface oxygen inhibition.

[0008] The photoinitiator in the above-mentioned prior art contains a quaternary ammonium group, which is connected to the thioxanthone aromatic ring through a methylene group. This structure has photosensitive decomposition characteristics, but the molecular structure of the photoinitiator has no polymerizable group, so it cannot be covalently bonded to the main chain of other organic polymers in the formulation system, and is easy to migrate in the curing material. The migration of the photoinitiator will cause harmful residues in the curing material, making the final product fail to meet the requirements of environmental regulations or safety standards, and is not suitable for use in fields with high safety requirements such as food and medicine. Summary of the invention

[0009] In view of the problems in the related art, the present invention proposes a thioxanthone photoinitiator intermediate and a preparation method thereof, and also discloses a water-based polymerizable thioxanthone photoinitiator and a preparation method thereof. By introducing water-soluble groups and polymerizable chemical groups into the thioxanthone structure, the water solubility and reaction efficiency of the initiator are significantly improved, and the photoinitiator prepared by the present invention can be covalently bonded to the polymer main chain after the photopolymerization reaction, so as to overcome the above-mentioned technical problems existing in the existing related technology, effectively solve the problem of photoinitiator migration, improve the safety and physical properties of the curing material containing the photoinitiator, and enable the photoinitiator prepared by the present invention to be applied to environmentally friendly water-based photocurable materials.

[0010] The technical solution of the present invention is achieved in this way:

[0011] A thioxanthone photoinitiator intermediate, whose molecular structure is shown in Formula I-6:

[0012]

[0013] The preparation method of the above-mentioned thioxanthone photoinitiator intermediate comprises the following steps:

[0014] 1) Thiosalicylic acid and thiophenol are prepared in a molar ratio of 0.8-1.2:0.8-1.2, and react under the condition of concentrated sulfuric acid as a catalyst to generate an intermediate I-3, the molecular structure of which is shown in Formula I-3:

[0015]

[0016] 2) The intermediate I-3 and the bromine-containing alkoxy compound are prepared in a molar ratio of 0.8-1.2:0.8-1.2, mixed and dissolved in an organic solvent, and a nucleophilic substitution reaction occurs under the condition of an alkaline catalyst to obtain an intermediate I-5, the molecular structure of which is shown in Formula I-5:

[0017]

[0018] 3) The intermediate I-5 and the imidazole compound are mixed in a molar ratio of 0.8-1.2:0.8-1.2, and a substitution reaction occurs to obtain the thioxanthone photoinitiator intermediate I-6.

[0019] Preferably, steps 1) to 3) are accompanied by heating, heat preservation and stirring during the reaction process, the reaction system is heated to 80-90° C. and kept warm, stirring is stopped after the reaction is completed, an inorganic salt solution is added to quench the reaction, and then the temperature is lowered to or below room temperature.

[0020] More preferably, the inorganic salt solution is one of saturated sodium chloride solution, potassium chloride and ammonium chloride.

[0021] Preferably, in step 2), the molecular structure of the alkoxy compound containing a bromine group is as shown in Formula I-4:

[0022]

[0023] Preferably, in step 2), the alkaline catalyst is one of triethylamine, ethylenediamine, 4-dimethylaminopyridine and potassium carbonate.

[0024] More preferably, step 1) comprises the following steps:

[0025] 1.1) Slowly add concentrated sulfuric acid to thiosalicylic acid and stir for at least 5 minutes. Slowly add thiophenol while stirring. The time for adding thiophenol is controlled to be at least 30 minutes. After the addition is completed, stir at room temperature for at least 1 hour.

[0026] 1.2) Raise the temperature to 80-90°C, keep stirring, react for 1.5-2h, and then let stand for at least 10h;

[0027] 1.3) Start stirring and keep stirring, add the mixed liquid prepared in step 1.2) into boiling water equal to or greater than 10 times its volume, and boil for 5 to 8 minutes;

[0028] 1.4) The boiled solution is cooled to room temperature, filtered to remove solid residue, and added to a 20-80% mass concentration of dioxane aqueous solution for recrystallization to obtain intermediate I-3.

[0029] More preferably, step 2) comprises the following steps:

[0030] 2.1) dissolving the intermediate I-3 obtained in step 1) in an organic solvent, adding a basic catalyst, wherein the molar ratio of the basic catalyst to the intermediate I-3 is 2 to 4:9, and then adding a bromine-containing alkoxy compound in a dropwise manner, wherein the total dropwise addition time is controlled to be at least 30 minutes;

[0031] 2.2) After the addition is complete, heat to 80-90°C and stir to react for 11-13 hours;

[0032] 2.3) After the reaction is completed, the feed solution obtained in step 2.2) is cooled to room temperature, and then an inorganic salt solution is added to quench the reaction;

[0033] 2.4) Separating the organic phase from the feed liquid of step 2.3), washing and drying the organic phase, removing the organic solvent, and performing chromatography to obtain intermediate I-5.

[0034] More preferably, step 3) comprises the following steps:

[0035] 3.1) Dissolve the intermediate I-5 obtained in step 2) in an organic solvent, and slowly add imidazole under stirring;

[0036] 3.2) Keep stirring, raise the temperature to 80-90°C, and stir for 5-7h;

[0037] 3.3) After the reaction is completed, the feed solution is cooled to room temperature, and then an inorganic salt solution is added to quench the reaction;

[0038] 3.4) Separating the organic phase from the liquid obtained in step 3.3), washing and drying the organic phase, removing the organic solvent, and performing chromatography to obtain the thioxanthone photoinitiator intermediate I-6.

[0039] Preferably, the organic solvent in the above steps 1) to 3) is one of toluene, xylene and chloroform, or a mixture of more than one of them in any proportion.

[0040] The present invention also discloses a water-based polymerizable thioxanthone photoinitiator, the molecular structure of which is shown in Formula S:

[0041]

[0042] Among them, X ˉ is at least one of fluoride, chloride, bromide, iodide, phosphate, sulfonate, carbonate, hexafluorophosphate or nitrate;

[0043] The structure of R is * is the linking position, and R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group.

[0044] Preferably, the alkyl group is C n H m , where n and m are independently natural numbers less than 30.

[0045] Preferably, the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0046] Preferably, the aqueous polymerizable thioxanthone photoinitiator is one of the following formulas S-1 to S-16:

[0047]

[0048] The maximum absorption wavelength range of the water-based polymerizable thioxanthone photoinitiator is 420-450 nm, and the absorbance is ≥1.0.

[0049] Specifically, when the polymerizable thioxanthone photoinitiator is of formula S-8 or formula S-13, when the concentration in deionized water reaches 1 mg / mL or more, the absorbance at a wavelength of 420 nm is 1.4 or more.

[0050] The method for preparing the above-mentioned water-based polymerizable thioxanthone photoinitiator comprises at least the following steps:

[0051] 1) preparing the above-mentioned thioxanthone photoinitiator intermediate I-6;

[0052] 2) The thioxanthone photoinitiator intermediate I-6 is subjected to an alkylation reaction with a brominated compound containing an acrylate at a molar ratio of 0.8 to 1.2:0.8 to 1.2 to obtain a water-based polymerizable thioxanthone photoinitiator I-8, the molecular structure of which is shown in Formula I-8:

[0053]

[0054] The structure of R is * is the linking position, and R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group.

[0055] Preferably, the alkyl group is C n H m , wherein n and m are independently natural numbers less than 30; the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0056] The present invention also discloses another method for preparing the above-mentioned water-based polymerizable thioxanthone photoinitiator, comprising the following steps:

[0057] 1) preparing the above-mentioned thioxanthone photoinitiator intermediate I-6;

[0058] 2) The thioxanthone photoinitiator intermediate I-6 is subjected to an alkylation reaction with a brominated compound containing an acrylate at a molar ratio of 0.8 to 1.2:0.8 to 1.2 to obtain an intermediate I-8 containing an imidazole ionic liquid unit, the molecular structure of which is shown in Formula I-8:

[0059]

[0060] The structure of R is * is the linking position, R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group;

[0061] 3) The intermediate I-8 and the ammonium salt NH4X are mixed in a molar ratio of 0.8-1.2:0.8-1.2, and an ion exchange reaction occurs to obtain a water-based polymerizable thioxanthone photoinitiator;

[0062] Wherein, X is at least one of fluoride ion, chloride ion, iodide ion, phosphate, sulfonate, carbonate, hexafluorophosphate or nitrate.

[0063] Preferably, the alkyl group is C n H m , wherein n and m are independently natural numbers less than 30; the molecular structure of the oligoether group is Here, m is a natural number less than 30.

[0064] Preferably, the ammonium salt is ammonium hexafluorophosphate.

[0065] Preferably, in step 2) of the above two preparation methods, heating and heat preservation operations and stirring operations are performed during the reaction process. The reaction system is heated to 80-90° C. and kept warm. After the reaction is completed, stirring is stopped and the temperature is lowered to or below room temperature.

[0066] More preferably, step 2) of the above two preparation methods comprises the following steps:

[0067] 2.1) dissolving the thioxanthone photoinitiator intermediate I-6 and the brominated compound containing acrylate in an organic solvent and stirring evenly;

[0068] 2.2) Raise the temperature to 80-90°C and stir for 9-11 hours;

[0069] 2.3) After the reaction is completed, the liquid is cooled to room temperature;

[0070] 2.4) adding water to the feed solution of step 5.3) and mixing, separating the aqueous phase after stratification, and extracting the aqueous phase several times with an organic extract to remove unreacted organic matter and by-products;

[0071] 2.5) removing water and drying to obtain water-based polymerizable thioxanthone photoinitiator I-8; if step 3) is included, intermediate I-8 is obtained.

[0072] Preferably, the organic solvent in step 2.1) is one of toluene, xylene and chloroform or a mixture of more than one of them in any proportion; the organic extract in step 5.4) is one of ethyl acetate, ether and dichloromethane.

[0073] Preferably, in the above two preparation methods, in step 2), the preparation method of the brominated compound containing acrylic acid ester comprises the following steps:

[0074] a) acryloyl chloride or a derivative of acryloyl chloride and 2-bromoethanol are mixed and dissolved in an organic solvent at a molar ratio of 0.8-1.2:0.8-1.2;

[0075] b) Start stirring and keep heating to 80-90°C, and stir for 5-7h;

[0076] c) After the reaction is completed, the feed solution is cooled to room temperature, and then an inorganic salt solution is added to quench the reaction;

[0077] d) Separating the organic phase from the feed liquid obtained in step 4.3), washing and drying the organic phase, removing the organic solvent, and purifying to obtain a brominated compound containing acrylic acid ester.

[0078] Preferably, the organic solvent in step a) is one of toluene, xylene and chloroform or a mixture of more than one of them in any proportion; and the inorganic salt solution in step c) is a saturated sodium chloride solution.

[0079] Preferably, in step 2) of the above two preparation methods, the brominated compound containing acrylate is one of the following formulas 1-3 to 8-3:

[0080]

[0081]

[0082] Preferably, the method for preparing the above-mentioned water-based polymerizable thioxanthone photoinitiator, step 3) comprises the following steps:

[0083] 3.1) Dissolve the intermediate I-8 in water, and slowly add the ammonium salt under stirring. The total time of adding the ammonium salt is at least 18 minutes;

[0084] 3.2) Keep stirring and react at room temperature for 3 to 5 hours;

[0085] 3.3) removing moisture from the solution obtained in step 3.2), then recrystallizing, filtering and drying to obtain an aqueous polymerizable thioxanthone photoinitiator.

[0086] The general synthesis formula of the water-based polymerizable thioxanthone photoinitiator of the present invention is shown in the figure below:

[0087]

[0088] Beneficial effects of the present invention:

[0089] The water-based polymerizable thioxanthone photoinitiator prepared by the thioxanthone photoinitiator intermediate further introduces a water-soluble quaternary ammonium salt group into the molecular structure, thereby achieving good water solubility and making it widely applicable to environmentally friendly water-based photocuring systems; at the same time, a polymerizable functional group is designed into the molecular structure, thereby achieving:

[0090] 1. Covalent bonding with polymers to avoid migration: By introducing polymerizable double bonds or other groups that can copolymerize with monomers into the thioxanthone structure, the initiator can participate in the polymerization with the polymer matrix in the polymerization reaction, thereby covalently bonding to the polymer main chain, which can effectively avoid the migration of the photoinitiator in the cured product after polymerization. Solving the migration problem can not only significantly improve the physical and chemical stability of the material, but also reduce the potential threat to the human body and the environment, making the material particularly suitable for use in medical, food packaging and other fields with high safety requirements.

[0091] 2. Improve the overall performance of the material: By introducing polymerizable groups, the photoinitiator is no longer a simple additive, but becomes a part of the polymer structure, which can improve the density of the entire polymer network and improve the material's mechanical strength, scratch resistance, chemical corrosion resistance and other properties.

[0092] 3. Improve reaction efficiency: The polymerizable photoinitiator can significantly improve the initiation efficiency because it can participate in the polymerization reaction, increase the concentration of free radicals and promote the reaction, thereby increasing the polymerization rate. It is especially suitable for some industrial applications that require rapid curing, such as high-speed coating curing and 3D printing, and is of great significance.

[0093] In summary, the present invention significantly improves the solubility, photoinitiation efficiency and safety of the photoinitiator in the aqueous system by targeted design of the molecular structure of the photoinitiator. The aqueous polymerizable thioxanthone photoinitiator prepared by the present invention exhibits good water solubility and high photoinitiation efficiency. At the same time, its molecular structure can copolymerize with the monomer in the photoinitiated polymerization reaction to achieve covalent bonding to the polymer main chain after curing, thereby effectively avoiding the migration problem of the photoinitiator, improving the physical properties and long-term stability of the material containing the aqueous polymerizable thioxanthone photoinitiator of the present invention, and is particularly suitable for application in various aqueous photocuring and high-efficiency photocuring industries. DETAILED DESCRIPTION

[0094] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments. Obviously, the described embodiments are only 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.

[0095] Example 1

[0096] The synthetic route of this embodiment is shown in the figure below:

[0097]

[0098] 1) Preparation of intermediate I-3

[0099] 1.1) 160 g of thiosalicylic acid (as shown in formula I-1, 1.0 mol) was slowly added to 1500 mL of concentrated sulfuric acid, stirred for 5 min to ensure adequate mixing, and then 600 g of thiophenol (as shown in formula I-2, 5.5 mol) was slowly added under stirring. The entire addition process lasted for 30 min. After the addition was completed, stirring was continued at room temperature for 1 h.

[0100] 1.2) The reaction mixture was heated to 80°C and kept reacting for 2 hours, and then allowed to stand at room temperature overnight (more than 10 hours).

[0101] 1.3) The next day, carefully pour the reaction mixture into boiling water equivalent to 10 times the original volume, stirring while pouring, and continue boiling for 5 minutes.

[0102] 1.3) The solution was cooled to room temperature and filtered to remove the solid residue. The solution was recrystallized in a 60% dioxane-water mixed solvent to obtain 195 g of intermediate I-3, i.e., 2-mercaptothioxanthone. The H NMR spectrum data were as follows:

[0103] 1 H NMR (500MHz, Chloroform) δ7.59–6.87(m,7H),3.45(s,1H).

[0104] 2) Preparation of intermediate I-5

[0105] 2.1) Weigh 183 g of the intermediate I-3 (0.75 mol) obtained in step 1) and dissolve it in 500 mL of toluene, and add 227.7 g of triethylamine (2.25 mol) as a basic catalyst; then weigh 206.25 g of an alkoxy compound (as shown in formula I-4, 0.75 mol) and slowly add it dropwise to the solution under stirring, and the addition process lasts for 30 minutes.

[0106] 2.2) After the dropwise addition was completed, the reaction mixture was heated to 80° C. and stirred for 12 h, during which the progress of the reaction was monitored by thin layer chromatography (TLC).

[0107] 2.3) After the reaction was completed, the mixture was cooled to room temperature and 500 mL of saturated sodium chloride solution was added to quench the reaction.

[0108] 2.4) The organic phase was separated using a separatory funnel, washed three times with 300 mL of water, dried over anhydrous sodium sulfate for 1 h, and then filtered to remove the desiccant.

[0109] 2.5) Finally, the organic phase was evaporated under reduced pressure to remove toluene to obtain a crude product, which was purified by column chromatography using petroleum ether / ethyl acetate as an eluent to obtain 260 g of intermediate I-5. The H NMR spectrum data was:

[0110] 1 H NMR (500MHz, Chloroform) δ7.68–6.80 (m, 7H), 3.99–3.66 (m, 4H), 3.60–3.36 (m, 6H), 3.25 (dd, J = 21.4, 7.4Hz, 2H).

[0111] 3) Preparation of thioxanthone photoinitiator intermediate I-6

[0112] 3.1) Weigh 219.5 g of the intermediate I-5 (0.5 mol) obtained in step 2) and dissolve it in 400 mL of toluene. Slowly add 38 g of imidazole (0.5 mol) under stirring and continue to stir the mixture.

[0113] 3.2) Raise the temperature to 80°C and react for 6 hours.

[0114] 3.3) After the reaction was completed, the reaction system was cooled to room temperature and 400 mL of saturated sodium chloride solution was added to quench the reaction.

[0115] 3.4) Separate the organic phase with a separatory funnel, wash the organic phase three times with 300 mL of water, dry it with anhydrous sodium sulfate for 1 h, and then filter to remove the desiccant.

[0116] 3.5) Toluene was distilled off under reduced pressure to obtain a crude product, which was purified by column chromatography using petroleum ether / ethyl acetate as an eluent to obtain 170 g of thioxanthone photoinitiator intermediate I-6, the H NMR spectrum data of which were:

[0117] 1 H NMR(500MHz,Chloroform)δ7.92(s,1H),7.58–7.25(m,5H),7.28–6.97(m,3H),6.78(d,J= 15.0Hz, 1H), 4.33 (t, J = 8.1Hz, 2H), 3.94–3.69 (m, 4H), 3.52 (s, 4H), 3.27 (t, J = 9.4Hz, 2H).

[0118] Example 2

[0119] The synthetic route of this embodiment is shown in the figure below:

[0120]

[0121] 4) Preparation of brominated compounds 1-3 containing acrylic acid esters

[0122] 4.1) Weigh 104 g of the compound represented by Formula 1-1 (1.0 mol) and 125 g of the compound represented by Formula 1-2 (1.0 mol), dissolve them in 300 mL of anhydrous toluene, place them in a three-necked flask, and install it in a condensation reflux device.

[0123] 4.2) The mixture was slowly heated to 80° C. under stirring and the reaction was maintained for 6 h to ensure that the reaction was complete. During the reaction, the reaction progress was monitored by thin layer chromatography (TLC).

[0124] 4.3) After the reaction was completed, heating was stopped and the reaction mixture was cooled to room temperature, and 200 mL of saturated sodium chloride solution was added to the reaction mixture to quench the reaction.

[0125] 4.4) Use a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of water, then dry it over anhydrous sodium sulfate for 1 hour, and filter it to remove the desiccant.

[0126] 4.5) Toluene was then distilled off under reduced pressure on a rotary evaporator to obtain a crude product; the crude product was purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 156 g of purified acrylate-containing brominated compound 1-3, the H NMR spectrum data of which were:

[0127] 1 H NMR (500MHz, Chloroform) δ6.73–6.06 (m, 2H), 4.64 (t, J = 7.9 Hz, 2H), 3.65 (t, J = 8.0 Hz, 2H), 2.01 (t, J = 2.0 Hz, 3H).

[0128] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-1

[0129] 5.1) Weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 (0.25 mol) obtained in Example 1, dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask; then weigh 68.75 g of the acrylate-containing brominated compound 1-3 (0.25 mol) obtained in step 4), slowly add it to the solution, and stir evenly.

[0130] 5.2) The reaction mixture was heated to 85°C and maintained for 10 h. The reaction was monitored by thin layer chromatography (TLC).

[0131] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0132] 5.4) 200 mL of deionized water was added and separated by a separatory funnel, and the aqueous phase was collected and extracted with ethyl acetate three times (50 mL each time) to remove unreacted organic matter and by-products.

[0133] 5.5) The aqueous phase was then concentrated under reduced pressure to obtain a crude ionic liquid product; further purified by evaporation under reduced pressure to remove residual water, and freeze-dried to finally obtain 121 g of purified aqueous polymerizable thioxanthone photoinitiator S-1, the H NMR spectrum data of which were:

[0134] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.62–7.22(m,5H),7.16(td,J=7.5,1.5 Hz,1H),7.09(d,J=1.3Hz,1H),6.59–6.25(m,2H),5.04(d,J=7.5Hz,1H),4.94(d, J=7.5Hz,1H),4.79(t,J=4.0Hz,2H),4.47(t,J=4.0Hz,2H),4.33(t,J=4.2Hz,2H ), 3.81 (dt, J = 15.7, 4.3Hz, 4H), 3.52 (s, 4H), 3.27 (t, J = 4.5Hz, 2H), 2.01 (s, 3H).

[0135] Example 3

[0136] The synthetic route of this embodiment is shown in the figure below:

[0137]

[0138] 4) Preparation of brominated compounds 2-3 containing acrylic acid esters

[0139] 4.1) Weigh 118 g of the compound shown in Formula 2-1 (1.0 mol), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask; then weigh 125 g of the compound shown in Formula 2-2 (1.0 mol), slowly add it to the solution under stirring, stir evenly, and continue stirring at room temperature for 30 minutes to ensure that the reactants are fully mixed.

[0140] 4.2) The reaction mixture was then heated to 90°C and maintained at this temperature for 6 hours to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0141] 4.3) After the reaction was completed, heating was stopped and the reaction mixture was cooled to room temperature, and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0142] 4.4) The organic phase was separated by separating the layers using a separatory funnel, and the organic phase was washed three times with 200 mL of deionized water to remove water-soluble by-products, and then dried over anhydrous sodium sulfate for 1 h and filtered to remove the desiccant.

[0143] 4.5) The organic phase was placed on a rotary evaporator to remove toluene under reduced pressure to obtain a crude product; the crude product was purified by recrystallization to obtain 134 g of a purified brominated compound 2-3 containing acrylic acid ester, and the H NMR spectrum data were:

[0144] 1 H NMR(500MHz,Chloroform)δ6.29(dt,J=4.1,2.0Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),4.64(t, J=15.0Hz, 2H), 3.65 (t, J=15.0Hz, 2H), 2.44 (qd, J=13.4, 11.5Hz, 2H), 1.07 (t, J=13.4Hz, 3H).

[0145] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-2

[0146] 5.1) Weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 (0.25 mol) obtained in Example 1, dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask; then weigh 51.25 g of the acrylate-containing brominated compound 2-3 (0.25 mol) obtained in step 4), slowly add it to the solution, and stir evenly.

[0147] 5.2) The reaction mixture was heated to 85°C and maintained for 10 h. The reaction was monitored by thin layer chromatography (TLC).

[0148] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0149] 5.4) 200 mL of deionized water was added to separate the layers, and the aqueous phase was collected to retain the ionic liquid. The aqueous phase was extracted three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0150] 5.5) The aqueous phase was then concentrated under reduced pressure to obtain a crude product of the ionic liquid; further purified by evaporation under reduced pressure to remove residual water, and freeze-dried to finally obtain 98 g of purified aqueous polymerizable thioxanthone photoinitiator S-2, the H NMR spectrum data of which were:

[0151] 1 H NMR (500MHz, Chloroform) δ8.92 (s, 1H), 7.56–7.24 (m, 2H), 7.14 (ddd, J = 22.5, 16.8, 3. 1Hz,1H),6.29(dt,J=4.1,2.0Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),4.96(d,J=7.5Hz,1H) ,4.85–4.70(m,1H),4.47(t,J=9.6Hz,1H),4.33(t,J=8.0Hz,1H),3.79(dt,J=17.1,9.0 Hz,1H),3.52(s,1H),3.27(t,J=10.0Hz,1H),2.67–2.23(m,1H),1.07(t,J=13.4Hz,1H).

[0152] Example 4

[0153] The synthetic route of this embodiment is shown in the figure below:

[0154]

[0155] 4) Preparation of brominated compound 3-3 containing acrylate

[0156] 4.1) Weigh 146 g of the compound shown in Formula 3-1 (1.0 mol), dissolve it in 300 mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125 g of the compound shown in Formula 3-2 (1.0 mol), slowly add it to the solution under stirring conditions, and the entire addition process lasts for 30 minutes to ensure that the two are fully mixed.

[0157] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0158] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0159] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0160] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was further purified by recrystallization. Ethanol was used for recrystallization to obtain 134 g of brominated compound 3-3 containing acrylate, and the H NMR spectrum data were:

[0161] 1 H NMR(500MHz,Chloroform)δ6.29(dt,J=4.1,2.0Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),4.64(t,J=8.0Hz ,2H),3.65(t,J=8.0Hz,2H),2.41(tt,J=11.2,1.8Hz,2H),1.62–1.09(m,4H),0.93(t,J=12.6Hz,3H).

[0162] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-3

[0163] 5.1) Weigh 58.75 g of the bromo compound 3-3 containing acrylate prepared in step 4) (0.25 mol), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 prepared in Example 1 (0.25 mol), slowly add it to the solution, and stir evenly.

[0164] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0165] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0166] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0167] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 94 g of purified aqueous polymerizable thioxanthone photoinitiator S-3, the H NMR spectrum data of which were:

[0168] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.61–6.91(m,7H),6.29(dt,J=4.1,1.9Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),5.24(d,J=7.5Hz,1H),4.93–4.60(m ,3H),4.56–4.19(m,4H),3.85(dt,J=12.9,8.4Hz,4H),3.52(s,4H),3.27(t, J=9.2Hz,2H),2.48–2.23(m,2H),1.62–1.07(m,4H),0.93(t,J=12.7Hz,3H).

[0169] Example 5

[0170] The synthetic route of this embodiment is shown in the figure below:

[0171]

[0172] 4) Preparation of brominated compound 4-3 containing acrylic acid ester

[0173] 4.1) Weigh 160g of the compound shown in Formula 4-1 (1.0mol), dissolve it in 300mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125g of the compound shown in Formula 4-2 (1.0mol), slowly add it to the solution under stirring conditions, and the entire addition process lasts for 30min to ensure that the two are fully mixed.

[0174] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0175] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0176] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0177] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was then purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 213 g of acrylate-containing brominated compound 4-3, the H NMR spectrum data of which were:

[0178] 1 H NMR(500MHz,Chloroform)δ6.29(dt,J=4.1,2.0Hz,1H),5.46(dt,J=4.0,1.9Hz,1H),4.64(t,J=7.7Hz,2H),3.6 5(t,J=7.6Hz,2H),2.41(tt,J=11.6,1.9Hz,2H),1.77–1.42(m,1H),1.40–1.22(m,2H),0.91(d,J=12.5Hz,6H).

[0179] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-4

[0180] 5.1) Weigh 62.25 g of the acrylate-containing brominated compound 4-3 (0.25 mol) obtained in step 4), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 (0.25 mol) obtained in Example 1, slowly add it to the solution, and stir evenly.

[0181] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0182] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0183] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0184] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 108 g of purified aqueous polymerizable thioxanthone photoinitiator S-4, the H NMR spectrum data of which were:

[0185] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.64–6.94(m,7H),6.29(dt,J=4.1,2.0Hz,1H ),5.46(dt,J=3.9,1.9Hz,1H),5.05–4.69(m,4H),4.40(dt,J=15.9,9.0Hz,4H),3.80(d t,J=23.2,8.0Hz,4H),3.52(s,4H),3.27(t,J=8.1Hz,2H),2.41(tt,J=11.4,1.9Hz,2H ), 1.59 (ddd, J = 23.3, 11.9, 5.9 Hz, 1H), 1.31 ( q, J = 11.2 Hz, 2H), 0.91 ( d, J = 12.5 Hz, 6H).

[0186] Example 6

[0187] The synthetic route of this embodiment is shown in the figure below:

[0188]

[0189] 4) Preparation of brominated compound 5-3 containing acrylic acid ester

[0190] 4.1) Weigh 166 g of the compound (1.0 mol) as shown in Formula 5-1, dissolve it in 300 mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125 g of the compound (1.0 mol) as shown in Formula 5-2, slowly add it to the solution under stirring conditions, and the entire addition process lasts for 30 minutes to ensure that the two are fully mixed.

[0191] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0192] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0193] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0194] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was then purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 225 g of acrylate-containing brominated compound 5-3, the H NMR spectrum data of which were:

[0195] 1 H NMR (500MHz, Chloroform) δ 7.59–7.26 (m, 3H), 7.29–6.89 (m, 2H), 6.28 (dd, J = 51.1, 4.2Hz, 2H), 4.64 (t, J = 8.0Hz, 2H), 3.65 (t, J = 8.0Hz, 2H).

[0196] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-5

[0197] 5.1) Weigh 63.5 g of the bromo compound 5-3 containing acrylate prepared in step 4) (0.25 mol), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 prepared in Example 1 (0.25 mol), slowly add it to the solution, and stir evenly.

[0198] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0199] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0200] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0201] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 113 g of purified aqueous polymerizable thioxanthone photoinitiator S-5, the H NMR spectrum data of which were:

[0202] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.57–7.26(m,8H),7.22–7.00(m,4H),6.20(d,J=4.2Hz,1H),5.90(d,J=4.2Hz,1H),4. 91(q,J=7.5Hz,2H),4.77(t,J=8.4Hz,2H),4.40(dt,J=22.3,9.8Hz,4H),3.89–3.69(m,4H),3.52(s,4H),3.27(t,J=8.9Hz,2H).

[0203] Example 7

[0204] The synthetic route of this embodiment is shown in the figure below:

[0205]

[0206] 4) Preparation of brominated compound 6-3 containing acrylic acid ester

[0207] 4.1) Weigh 180g of the compound (1.0mol) as shown in Formula 6-1, dissolve it in 300mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125g of the compound (1.0mol) as shown in Formula 6-2, and slowly add it to the solution under stirring conditions. The entire addition process lasts for 30min to ensure that the two are fully mixed.

[0208] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0209] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0210] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0211] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was then purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 215 g of bromo compound 6-3 containing acrylate, and the H NMR spectrum data were:

[0212] 1 H NMR (500MHz, Chloroform) δ7.39–6.91 (m, 4H), 6.26 (dd, J = 74.5, 4.2Hz, 2H), 4.64 (t, J = 13.6Hz, 2H), 3.65 (t, J = 13.6Hz, 2H), 2.41 (s, 3H).

[0213] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-6

[0214] 5.1) Weigh 67 g of the acrylate-containing brominated compound 6-3 (0.25 mol) obtained in step 4), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 (0.25 mol) obtained in Example 1, slowly add it to the solution, and stir evenly.

[0215] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0216] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0217] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0218] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 93 g of purified aqueous polymerizable thioxanthone photoinitiator S-6, the H NMR spectrum data of which were:

[0219] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),7.57–6.98(m,11H),6.39(d,J=4.0Hz,1H),6.11(d,J=4.2Hz,1H),4.80(ddd,J=53.9, 26.8, 4.0Hz, 4H), 4.40 (dt, J = 70.1, 8.4Hz, 4H), 3.80 (dt, J = 52.2, 8.5Hz, 4H), 3.52 (s, 4H), 3.27 (t, J = 8.4Hz, 2H), 2.41 (s, 3H).

[0220] Example 8

[0221] The synthetic route of this embodiment is shown in the figure below:

[0222]

[0223] 4) Preparation of brominated compound 7-3 containing acrylate

[0224] 4.1) Weigh 180g of the compound (1.0mol) as shown in Formula 7-1, dissolve it in 300mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125g of the compound (1.0mol) as shown in Formula 7-2, and slowly add it to the solution under stirring conditions. The entire addition process lasts for 30min to ensure that the two are fully mixed.

[0225] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0226] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0227] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0228] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was then purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 241 g of acrylate-containing brominated compound 7-3, the H NMR spectrum data of which were:

[0229] 1H NMR (500MHz, Chloroform) δ7.57–6.84(m,5H),6.12(dt,J=4.1,1.9Hz,1H),5.40(dt,J=4.1,2.0Hz,1H),4.64(t,J=15.0Hz,2H),3.83–3.33(m,4H).

[0230] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-7

[0231] 5.1) Weigh 67 g of the acrylate-containing brominated compound 7-3 (0.25 mol) obtained in step 4), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 106.5 g of the thioxanthone photoinitiator intermediate I-6 (0.25 mol) obtained in Example 1, slowly add it to the solution, and stir evenly.

[0232] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0233] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0234] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0235] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 109 g of purified aqueous polymerizable thioxanthone photoinitiator S-7, the H NMR spectrum data of which were:

[0236] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.54–6.97(m,12H),6.12(dt,J=4.1,1.9Hz,1H),5.40(dt,J=4.1,2.0Hz,1H),4.86(t,J=8.1Hz,2H ), 4.68(dd,J=7.5,0.6Hz,1H), 4.40(dt,J=69.5,8.1Hz,4H), 3.83(ddd,J=28.7,15.9,8.6Hz,5H), 3.60–3.43(m,6H), 3.27(t,J=9.2Hz,2H).

[0237] Example 9

[0238] The synthetic route of this embodiment is shown in the figure below:

[0239]

[0240] 4) Preparation of brominated compound 8-3 containing acrylate

[0241] 4.1) Weigh 114 g of the compound shown in Formula 8-1 (1.0 mol), dissolve it in 300 mL of anhydrous toluene, place it in a three-necked flask, and install it in a condensation reflux device; then weigh 125 g of the compound shown in Formula 8-2 (1.0 mol), slowly add it to the solution under stirring conditions, and the entire addition process lasts for 30 minutes to ensure that the two are fully mixed.

[0242] 4.2) After the addition was completed, the reaction mixture was heated to 90° C. and maintained for 8 h to promote the reaction, during which the reaction progress was monitored by thin layer chromatography (TLC).

[0243] 4.3) After the reaction was completed, the reaction mixture was cooled to room temperature and 300 mL of saturated sodium chloride solution was added to quench the reaction.

[0244] 4.4) Separate the layers using a separatory funnel to separate the organic phase, wash the organic phase three times with 200 mL of deionized water to remove water-soluble impurities, dry the organic phase over anhydrous sodium sulfate for 1 h, and filter to remove the desiccant.

[0245] 4.5) The organic phase was placed in a rotary evaporator, and toluene was distilled off under reduced pressure to obtain a crude product, which was then purified by column chromatography using petroleum ether / ethyl acetate as eluent to obtain 174 g of acrylate-containing brominated compound 8-3, the H NMR spectrum data of which were:

[0246] 1 H NMR (500MHz, Chloroform) δ6.99 (d, J = 4.2 Hz, 1H), 6.56 (d, J = 4.0 Hz, 1H), 4.65 (t, J = 15.0 Hz, 2H), 3.65 (t, J = 15.0 Hz, 2H).

[0247] 5) Preparation of water-based polymerizable thioxanthone photoinitiator S-8

[0248] 5.1) Weigh 50.5 g of the bromo compound 8-3 containing acrylate prepared in step 4) (0.25 mol), dissolve it in 200 mL of anhydrous toluene, and place it in a three-necked flask. Then weigh 165.5 g of the thioxanthone photoinitiator intermediate I-6 prepared in Example 1 (0.25 mol), slowly add it to the solution, and stir evenly.

[0249] 5.2) The reaction mixture was heated to 85° C. and maintained for 10 h to ensure that the reaction proceeded fully; the reaction was monitored by thin layer chromatography (TLC).

[0250] 5.3) After the reaction is complete, stop heating and cool to room temperature.

[0251] 5.4) Add 200 mL of deionized water to the reaction mixture, separate the layers using a separatory funnel, collect the aqueous phase, and extract the aqueous phase three times with ethyl acetate (50 mL each time) to remove unreacted organic matter and by-products.

[0252] 5.5) The aqueous phase was then concentrated under reduced pressure to remove most of the water, followed by freeze drying, to finally obtain 86 g of purified aqueous polymerizable thioxanthone photoinitiator S-8, the H NMR spectrum data of which were:

[0253] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.58–7.25(m,5H),7.14(ddd,J=22.5,16.8,3.1Hz,2H),6.67(d,J=4.2Hz,1H),6. 46(d,J=4.2Hz,1H),4.97–4.63(m,4H),4.56–4.21(m,4H),3.83(td,J=8.5,2.5Hz,4H),3.52(s,4H),3.27(t,J=8.6Hz,2H).

[0254] Example 10

[0255] The synthetic route of this embodiment is shown in the figure below:

[0256]

[0257] 6.1) Weigh 61.8 g of S-1 obtained in Example 2, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate and slowly add it to the aqueous solution of S-1. Keep stirring the solution so that the two are fully mixed to carry out ion exchange reaction. The whole addition process takes about 20 minutes.

[0258] 6.2) After the addition is complete, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0259] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 59.4 g of purified aqueous polymerizable thioxanthone photoinitiator S-9, and the H NMR spectrum data are:

[0260] 1 H NMR(500MHz,Chloroform)δ8.86(s,1H),7.54–7.22(m,5H),7.09(ddd,J=22.4,16.7,3.1Hz,2H),6.39(ddq,J=39.9,4.0,2.0Hz,2H),5.05(d,J=7.5H z,1H),4.85–4.62(m,3H),4.44(t,J=7.8Hz,2H),4.30(t,J=7.6Hz,2H),3. 92–3.69(m,4H),3.49(s,4H),3.25(t,J=8.2Hz,2H),2.00(t,J=1.9Hz,3H).

[0261] Embodiment 11

[0262] The synthetic route of this embodiment is shown in the figure below:

[0263]

[0264] 6.1) Weigh 63.3 g of S-2 prepared in Example 3, dissolve it in 150 mL of deionized water, and place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-2, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole addition process takes about 20 minutes.

[0265] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0266] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 53.6 g of purified aqueous polymerizable thioxanthone photoinitiator S-10, and the H NMR spectrum data are:

[0267] 1H NMR(500MHz,Chloroform)δ8.90(s,1H),7.66–7.29(m,5H),7.22–6.94(m,2H),6.28(dt,J=4.1,1 .9Hz,1H),5.45(dt,J=4.0,2.0Hz,1H),5.04(d,J=7.5Hz,1H),4.89(dd,J=7.5,0.6Hz,1H),4.78(t d,J=14.3,1.0Hz,2H),4.46(td,J=14.3,1.0Hz,2H),4.32(t,J=7.8Hz,2H),3.80(dt,J=14.2,8.1 Hz, 4H), 3.51 (s, 4H), 3.26 (t, J = 8.4Hz, 2H), 2.44 (qt, J = 13.2, 1.8Hz, 2H), 1.07 (t, J = 13.4Hz, 3H).

[0268] Example 12

[0269] The synthetic route of this embodiment is shown in the figure below:

[0270]

[0271] 6.1) Weigh 66.1 g of S-3 prepared in Example 4, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-3, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole addition process takes about 20 minutes.

[0272] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0273] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 61.4 g of purified aqueous polymerizable thioxanthone photoinitiator S-11, and the H NMR spectrum data are:

[0274] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),7.57–7.29(m,5H),7.14(ddd,J=22.5,16.7,3.1Hz,2H),6.29 (dt,J=4.1,2.0Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),5.25(d,J=7.5Hz,1H),4.78(dd,J=16.6,5.6Hz,2H ),4.62(d,J=7.5Hz,1H),4.46(dd,J=16.5,5.7Hz,2H),4.33(t,J=7.6Hz,2H),3.85(dt,J=12.9,8.4Hz, 4H), 3.52 (s, 4H), 3.27 (t, J = 9.2Hz, 2H), 2.54–2.32 (m, 2H), 1.56–1.07 (m, 4H), 0.93 (t, J = 12.7Hz, 3H).

[0275] Embodiment 13

[0276] The synthetic route of this embodiment is shown in the figure below:

[0277]

[0278] 6.1) Weigh 67.5 g of S-4 obtained in Example 5, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-4, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole addition process takes about 20 minutes.

[0279] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0280] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 55.9 g of purified aqueous polymerizable thioxanthone photoinitiator S-12, and the H NMR spectrum data are:

[0281] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),7.53–7.28(m,5H),7.14(ddd,J=22.5,16.7,3.1Hz,2H),6.29(d t,J=4.1,2.0Hz,1H),5.46(dt,J=4.1,2.0Hz,1H),5.25(d,J=7.5Hz,1H),4.78(dd,J=16.6,5.6Hz,2H),4 .62(d,J=7.5Hz,1H),4.46(dd,J=16.5,5.7Hz,2H),4.33(t,J=7.6Hz,2H),3.85(dt,J=12.9,8.4Hz,4H), 3.52(s,4H),3.27(t,J=9.2Hz,2H),2.56–2.26(m,2H),1.49–1.11(m,4H),0.93(dd,J=15.0,10.5Hz,3H).

[0282] Embodiment 14

[0283] The synthetic route of this embodiment is shown in the figure below:

[0284]

[0285] 6.1) Weigh 68.1 g of S-5 obtained in Example 6, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-5, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole adding process takes about 20 minutes.

[0286] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0287] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 73.5 g of purified aqueous polymerizable thioxanthone photoinitiator S-13, and the H NMR spectrum data are:

[0288] 1H NMR(500MHz,Chloroform)δ8.92(s,1H),7.58–7.29(m,8H),7.20–7.01(m,4H),6.18(dd,J=35.5,4.2Hz,2H),4.97(d,J=7.5Hz,1H) ,4.87–4.70(m,3H),4.47(t,J=7.8Hz,2H),4.33(t,J=8.0Hz,2H),3.81(dt,J=14.7,8.7Hz,4H),3.52(s,4H),3.27(t,J=9.4Hz,2H).

[0289] Embodiment 15

[0290] The synthetic route of this embodiment is shown in the figure below:

[0291]

[0292] 6.1) Weigh 69.4 g of S-6 obtained in Example 7, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-6, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole adding process takes about 20 minutes.

[0293] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0294] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 61.5 g of purified aqueous polymerizable thioxanthone photoinitiator S-14, and the H NMR spectrum data are:

[0295] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.57–7.30(m,5H),7.26–6.98(m,6H),6.30(d,J=4.2Hz,1H),6.08(d,J=4.2Hz,1H),5.26(dd,J=7.5,0 .6Hz,1H),4.83(t,J=8.8Hz,2H),4.47(t,J=8.8Hz,2H),4.36–4.12(m,3 H), 3.92–3.63 (m, 4H), 3.52 (s, 4H), 3.27 (t, J = 9.6Hz, 2H), 2.41 (s, 3H).

[0296] Example 16

[0297] The synthetic route of this embodiment is shown in the figure below:

[0298]

[0299] 6.1) Weigh 69.5 g of S-7 prepared in Example 8, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-7, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole adding process takes about 20 minutes.

[0300] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0301] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 65.3 g of purified aqueous polymerizable thioxanthone photoinitiator S-15, and the H NMR spectrum data are:

[0302] 1 H NMR (500MHz, Chloroform) δ8.92 (s, 1H), 7.54–7.01 (m, 12H), 6.12 (dt, J = 4.1, 1.9Hz,1H),5.40(dt,J=4.1,2.0Hz,1H),5.23(d,J=7.5Hz,1H),5.09(d,J=7.5 Hz,1H),4.75(dd,J=16.0,5.5Hz,2H),4.46(dd,J=15.9,5.6Hz,2H),4.33(t,J =8.4Hz, 2H), 3.79 (q, J = 8.7Hz, 4H), 3.62–3.40 (m, 6H), 3.27 (t, J = 9.0Hz, 2H).

[0303] Embodiment 17

[0304]

[0305] 6.1) Weigh 62.9 g of S-8 prepared in Example 9, dissolve it in 150 mL of deionized water, place it in a three-necked flask, and install a stirring device. Then weigh 16.3 g of ammonium hexafluorophosphate, slowly add it to the aqueous solution of S-8, keep stirring, and make the two fully mixed to carry out ion exchange reaction. The whole adding process takes about 20 minutes.

[0306] 6.2) After the addition is completed, continue to stir the reaction at room temperature for 4 hours to ensure that the reaction is complete.

[0307] 6.3) After the reaction is completed, the mixture is evaporated under reduced pressure to remove most of the water to obtain a crude product. The crude product is then dissolved in 100 mL of anhydrous ethanol for recrystallization, the filter cake is collected after filtration, and dried in a vacuum drying oven to constant weight to obtain 57.4 g of purified aqueous polymerizable thioxanthone photoinitiator S-16, and the H NMR spectrum data are:

[0308] 1 H NMR(500MHz,Chloroform)δ8.92(s,1H),7.55–7.24(m,5H),7.22–7.11(m,1H),7.09(d,J=2.5Hz,1H),6.82(d,J=4.2Hz,1H),6.57(d,J=4.2Hz,1H), 4.89(s,2H),4.78(t,J=9.2Hz,2H),4.47(t,J=9.2Hz,2H),4.33(t,J=8.4 Hz, 2H), 3.79 (dd, J = 13.3, 5.1 Hz, 4H), 3.52 (s, 4H), 3.27 (t, J = 9.2 Hz, 2H).

[0309] Performance Testing

[0310] (I) Solubility and dispersibility experiments: The solubility or dispersibility of S1-S16 in water was evaluated to determine their application potential in water-based photocuring systems.

[0311] Experimental steps:

[0312] 1. Sample preparation: Weigh S1 to S16 and prepare solutions with a concentration of 1 mg / mL.

[0313] 2. Stirring and dissolving: Add samples S1 to S16 into deionized water and stir using a magnetic stirrer for 30 minutes.

[0314] 3. Solubility evaluation: The state of each solution was visually observed and the dissolution of T1 to T16 in water was recorded.

[0315] 4. UV-Visible spectroscopy: Use a UV-Visible spectrometer to measure the absorbance of each sample at the maximum absorption wavelength.

[0316] The experimental results are shown in the following table.

[0317]

[0318] S1~S16 all show good water solubility, which indicates that by introducing water-soluble groups, the polymerizable thioxanthone photoinitiator prepared by the present invention has good solubility in water, is suitable for water-based photocuring system, meets the requirements of environmental protection and sustainable development, and overcomes the disadvantage that traditional oily photoinitiators are difficult to apply to water-based systems; on the other hand, the maximum absorption wavelength range of the water-based polymerizable thioxanthone photoinitiators S1~S16 is 420~450nm, and the absorbance range is 1.0~1.4.

[0319] (ii) Photo-initiation efficiency experiment: Determine the initiation efficiency of S1-S16 under UV light and evaluate their performance under different illumination times and concentrations.

[0320] Experimental steps:

[0321] 1. Sample preparation: Prepare a solution containing acrylate monomer (PEGDA), and add S1 to S16 to prepare a mixed solution with a concentration of 1 wt%.

[0322] 2. UV curing: Place the above samples in a quartz vial and use a UV curing system (wavelength 365nm, light intensity 500mW / cm 2 ) The samples were irradiated with ultraviolet light and the light response was recorded at different time periods (10 seconds, 30 seconds, 1 minute, and 5 minutes).

[0323] 3. Viscosity measurement: Measure the viscosity change of the solution after different illumination times.

[0324] 4. FT-IR monitoring: Use Fourier transform infrared spectrometer to monitor the polymerization reaction in real time, detect the intensity change of the characteristic peak of acrylate C=C double bond (about 1630 cm-1), and calculate the initiation efficiency.

[0325] 5.DSC exothermic measurement: Differential scanning calorimetry (DSC) was used to measure the exothermicity of the polymerization reaction and to evaluate the reaction rate.

[0326] The experimental results are shown in the following table.

[0327]

[0328]

[0329] Samples containing S1 to S16 showed high initiation efficiency under ultraviolet light, especially under long-term light exposure, the efficiency of the polymerization reaction increased significantly, S-8 and S-13 showed the highest initiation efficiency, achieved rapid curing and high polymerization rate, and are suitable for application in industrial fields requiring fast photocuring, such as high-speed coating curing and 3D printing.

[0330] (III) Initiator migration experiment: Based on the material synthesis, evaluate whether S1~S16 migrate after the polymer is cured, verify its initiation efficiency and judge its stability.

[0331] Experimental steps:

[0332] 1. Film preparation: A mixture of the above-mentioned S1-S16 with a concentration of 1 wt % and acrylate monomers is cured by a UV curing system to prepare a polymer film.

[0333] 2. Immersion experiment: The prepared polymer film was immersed in water for 24 h, 48 h and 72 h.

[0334] 3. Absorption peak detection: Take out solution samples every 24 hours, use UV-visible spectrometer to detect whether there is photoinitiator in the immersion solution, and evaluate the migration by detecting the changes in characteristic absorption peaks.

[0335] 4. HPLC detection: Use high performance liquid chromatography (HPLC) to quantitatively analyze the concentration of the photoinitiator in the immersion solution.

[0336] The experimental results are shown in the following table.

[0337]

[0338]

[0339] S1~S16 all showed low mobility after the polymer was cured, and there was almost no migration phenomenon in the aqueous medium, indicating that S1~S16 had good long-term stability. This shows that the present invention introduces a polymerizable group into the thioxanthone structure, so that the photoinitiator prepared by the present invention can be covalently bonded to the polymer matrix, thereby avoiding the migration problem of traditional photoinitiators in the polymer, significantly improving the physicochemical stability of the cured material, reducing the potential threat to the human body and the environment, and ensuring the environmental protection and safety of the final product. It is particularly suitable for fields with high safety requirements such as medical and food packaging.

[0340] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs may also change and modify the above implementation modes. Therefore, the present invention is not limited to the specific implementation modes disclosed and described above, and some modifications and changes to the present invention should also fall within the protection scope of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A thioxanthone photoinitiator intermediate, characterized in that: Its molecular structure is shown in formula I-6:

2. The method for preparing the thioxanthone photoinitiator intermediate according to claim 1, characterized in that: At least the following steps are included: 1) Thiosalicylic acid and thiophenol are prepared in a molar ratio of 0.8-1.2:0.8-1.2, and react under the condition of concentrated sulfuric acid as a catalyst to generate an intermediate I-3, the molecular structure of which is shown in Formula I-3: 2) The intermediate I-3 and the bromine-containing alkoxy compound are prepared in a molar ratio of 0.8-1.2:0.8-1.2, mixed and dissolved in an organic solvent, and a nucleophilic substitution reaction occurs under the condition of an alkaline catalyst to obtain an intermediate I-5, the molecular structure of which is shown in Formula I-5: 3) The intermediate I-5 and the imidazole compound are mixed in a molar ratio of 0.8-1.2:0.8-1.2, and a substitution reaction occurs to obtain the thioxanthone photoinitiator intermediate I-6.

3. The method for preparing a thioxanthone photoinitiator intermediate according to claim 2, characterized in that: During the reaction process of steps 1) to 3), heating, heat preservation and stirring are performed. The reaction system is heated to 80-90° C. and kept warm. After the reaction is completed, stirring is stopped and an inorganic salt solution is added to quench the reaction, and then the temperature is lowered to or below room temperature.

4. A water-based polymerizable thioxanthone photoinitiator, characterized in that: Its molecular structure is shown in formula S: Wherein, Xˉ is at least one of fluoride, chloride, bromide, iodide, phosphate, sulfonate, carbonate, hexafluorophosphate or nitrate; The structure of R is * is the linking position, and R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group.

5. The water-based polymerizable thioxanthone photoinitiator according to claim 4, characterized in that: It is one of formula S-1 to formula S-16:

6. The water-based polymerizable thioxanthone photoinitiator according to claim 5, characterized in that: The maximum absorption wavelength range is 420-450nm, and the absorbance is ≥1.

0.

7. A method for preparing a water-based polymerizable thioxanthone photoinitiator, characterized in that: At least the following steps are included: 1) preparing the thioxanthone photoinitiator intermediate I-6 according to claim 1; 2) The thioxanthone photoinitiator intermediate I-6 is subjected to an alkylation reaction with a brominated compound containing an acrylate at a molar ratio of 0.8 to 1.2:0.8 to 1.2 to obtain a water-based polymerizable thioxanthone photoinitiator I-8, the molecular structure of which is shown in Formula I-8: The structure of R is * is the linking position, and R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group.

8. The method for preparing the water-based polymerizable thioxanthone photoinitiator according to claim 7, characterized in that: In step 2), the brominated compound containing acrylate is one of the following formulas 1-3 to 8-3:

9. A method for preparing a water-based polymerizable thioxanthone photoinitiator, characterized in that: The following steps are involved: 1) preparing the thioxanthone photoinitiator intermediate I-6 according to claim 1; 2) The thioxanthone photoinitiator intermediate I-6 is subjected to an alkylation reaction with a brominated compound containing an acrylate at a molar ratio of 0.8 to 1.2:0.8 to 1.2 to obtain an intermediate I-8, the molecular structure of which is shown in Formula I-8: The structure of R is * is the linking position, R' is an alkyl group, a cyano group, an aryl group, a substituted aryl group, a benzyl group, a substituted benzyl group or an oligoether group; 3) The intermediate I-8 and the ammonium salt NH4X are mixed in a molar ratio of 0.8-1.2:0.8-1.2, and an ion exchange reaction occurs to obtain a water-based polymerizable thioxanthone photoinitiator; Wherein, X is at least one of fluoride ion, chloride ion, iodide ion, phosphate, sulfonate, carbonate, hexafluorophosphate or nitrate.

10. The method for preparing the water-based polymerizable thioxanthone photoinitiator according to claim 9, characterized in that: In step 2), the brominated compound containing acrylate is one of the following formulas 1-3 to 8-3:

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