Photoinitiator with sulfur-containing heterocyclic ring containing unsaturated carbon-carbon double bond as well as preparation method and application of photoinitiator

Abstract

The invention discloses a photoinitiator containing unsaturated carbon-carbon double bonds in a sulfur-containing heterocyclic ring. The structure of the photoinitiator is shown as a formula (I) or a formula (II): (I) and (II), wherein Rn is single substitution or multi-substitution on a benzene ring, and Rn is selected from one of hydrogen atom, alkyl, N-alkyl, O-alkyl, S-alkyl, Se-alkyl, Si-alkyl, aromatic ring group and acyloxy. The photoinitiator provided by the invention has polymerizable carbon-carbon double bond groups, can initiate free radical polymerization reaction, can participate in the polymerization reaction, serves as a cross-linking agent and is combined with a photocuring system, and after the photoinitiator enters the photocuring system to be cured, the mobility of residual micromolecules in the photocuring system is remarkably reduced, and the odor is also reduced; the toxicity of a photocuring system is further reduced, and industrial production and application are facilitated.

Description

Technical Field

[0001] This invention relates to the field of photoinitiator technology, specifically to a photoinitiator containing unsaturated carbon-carbon double bonds within a sulfur-containing heterocyclic ring, its preparation method, and its application. Background Technology

[0002] Photopolymerization technology is a technique that uses photoinitiators to absorb photon energy under ultraviolet or visible light irradiation, and initiates a chain reaction to form polymers through free radical or cationic mechanisms.

[0003] Since the 1990s, with the advent of photoinitiators such as isopropylthioxanthone (ITX), 2,4,6-trimethylbenzoyldiphenyl phosphine oxide (TPO), and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (also known as photoinitiator 819), UV curing has seen substantial development. Compared to traditional thermosetting coatings, UV-cured coatings offer advantages such as faster curing speed, room temperature curing, energy saving, space saving, environmental friendliness, improved product performance, and suitability for high-speed automated production.

[0004] However, photoinitiators can migrate from photocured products into the environment. How to effectively reduce or eliminate the migration rate of photoinitiators to make photopolymer products more environmentally friendly and safe is an urgent issue that needs to be addressed.

[0005] To address this issue, various novel photoinitiators have been introduced, such as macromolecular photoinitiators HMPP-1, HMPP-2, Ominopol BP, Ominopol TX, Ominopol ASA, Ominopol SZ, and Ominopol 910. However, they still have problems, such as poor compatibility with monomers or resins, tendency to cause excessive local crosslinking density, poor photoinitiation efficiency, and high usage costs, which cannot meet the requirements of practical applications. Therefore, developing a photoinitiator with high monomer / resin compatibility, low migration, and high initiation activity is an urgent problem to be solved. Summary of the Invention

[0006] The purpose of this invention is to provide a photoinitiator containing unsaturated carbon-carbon double bonds within a sulfur-containing heterocycle, its preparation method, and its application. This photoinitiator exhibits low mobility and high reactivity, thus solving the problems of low efficiency and high mobility in existing photoinitiators.

[0007] This invention is achieved through the following technical solutions:

[0008] A photoinitiator containing an unsaturated carbon-carbon double bond within a sulfur-containing heterocyclic ring, characterized by a structure as shown in formula (I) or formula (II): (I) (II);

[0009] Where R n For single or multiple substitutions on the benzene ring, R n It is selected from one of hydrogen atom, alkyl, N-alkyl, O-alkyl, S-alkyl, Se-alkyl, Si-alkyl, aromatic cycloyl, and acyloxy group.

[0010] Preferably, the alkyl group is a C1-C5 alkyl group.

[0011] The method for preparing the photoinitiator includes the following steps:

[0012] S1: Benzene compounds were dissolved in an organic solvent. Aluminum trichloride was added in batches at 0-5℃ under nitrogen protection. Halogenated benzoyl chloride was added dropwise while maintaining the low temperature at 0-5℃. The reaction was kept at this temperature. After the reaction was completed by GC monitoring, the mixture was poured into ice water. Hydrochloric acid was added to adjust the pH to 2. The mixture was separated into liquid and liquid phases. The organic phase was post-treated and recrystallized with an ether solvent to obtain a white solid A.

[0013] X is selected from F, Cl, and Br, and X is substituted at the ortho or para position.

[0014] S2: Add the white solid A obtained in step S1 to the pressure-resistant tube, add water, mercaptopropionic acid, inorganic base, replace nitrogen gas, react at 120-150℃, monitor the reaction by TLC, adjust the pH to 3 with hydrochloric acid, a large amount of solid precipitates out, continue stirring, filter, dry the filter cake, slurry with ether solvent for 2 hours, filter, dry the filter cake to obtain white solid B.

[0015] S3: Add concentrated sulfuric acid to the reaction flask, cool to 10°C, and then add the white solid B obtained in step S2 in batches. After the addition is complete, stir at room temperature, and then heat to 30-50°C to react. After the reaction is complete, TLC is used to detect the reaction. Then slowly pour the reaction solution into ice water to precipitate the solid. Filter, wash the filter cake with water, and then slurry with methanol to obtain a slightly yellow solid C.

[0016] S4: Under nitrogen protection, add the pale yellow solid C obtained in step S3 to the reaction flask, add potassium iodide and elemental iodine, then add dimethyl sulfoxide, heat to 120-140℃ and react. TLC detects that the reaction is complete. Pour the reaction solution into ice water to precipitate the solid, filter, wash the filter cake with water, slurry with methanol, filter, and obtain brown solid D.

[0017] Preferably, in step S1, the molar ratio of benzene compounds, aluminum trichloride, and halogenated benzoyl chloride is 1:1-1.05:1-1.05; the organic solvent is selected from one or two of dichloromethane, dichloroethane, chloroform, n-hexane, cyclohexane, and petroleum ether; the post-treatment of the organic phase includes the following steps: the organic phase is washed with saturated sodium bicarbonate, washed with water, washed with saturated brine, dried, and concentrated to dryness; the ether solvent is selected from one or two of methyl tert-butyl ether, diethyl ether, methyl ethyl ether, and propyl ether.

[0018] Preferably, in step S2, the molar ratio of white solid A, mercaptopropionic acid, and inorganic base is 1:1.14-1.25:2.08-2.6; the inorganic base is selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the reaction time is 5-9 hours; and the ether solvent is selected from one or two of methyl tert-butyl ether, diethyl ether, methyl ethyl ether, and propyl ether.

[0019] Preferably, in step S3, the molar ratio of concentrated sulfuric acid to white solid B is 1-1.1:1.

[0020] Preferably, in step S4, the molar ratio of potassium iodide, elemental iodine, and pale yellow solid C is 0.05-0.1:0.015-0.025:1; and the reaction time is 6-10 h.

[0021] The present invention also protects the use of the photoinitiator in the preparation of inks.

[0022] The beneficial effects of this invention are:

[0023] The photoinitiators of formulas (I) and (II) provided by this invention not only have the structures of benzophenone and some thioxanthone, but also contain polymerizable carbon-carbon double bond groups. Therefore, compared with traditional benzophenone-based photoinitiators and thioxanthone-based photoinitiators, because they have polymerizable carbon-carbon double bond groups, they can not only initiate free radical polymerization reactions, but also participate in polymerization reactions. Thus, they can also act as crosslinking agents in the system and can combine with the photocuring system. After entering the photocuring system for curing, the migration rate of residual small molecules in the photocuring system is significantly reduced, the odor in the photocuring system is also reduced, further reducing the toxicity of the photocuring system, making it more environmentally friendly, with a wider range of applications, and the raw materials are relatively easy to obtain, with lower production costs, making it more conducive to industrial production and application. Detailed Implementation

[0024] The following is a further description of the invention, but not a limitation thereof.

[0025] Example 1: Preparation of 8-(2,4,5-trimethylbenzoyl)-4H-thiochromene-4-one

[0026] The reaction steps are as follows: 24g of 1,2,4-trimethylbenzene was added to a 250ml dry three-necked flask, followed by 80ml of dry dichloroethane. The mixture was then placed under nitrogen protection and cooled to 0℃. 26.8g of aluminum trichloride was added in portions. After the addition was complete, the temperature was allowed to drop to 0℃ before adding 35.5g of o-chlorobenzoyl chloride dropwise, keeping the internal temperature below 5℃. After the addition was complete, the mixture was kept at 5-10℃ for two hours. After the reaction was complete as monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated into liquid and liquid phases. The organic phase was washed with saturated sodium bicarbonate, water, and saturated brine, respectively. The organic phase was dried and concentrated to dryness. Recrystallization with methyl tert-butyl ether yielded 48g of white solid Al, with a yield of 92.91%.

[0027] 25g of white solid A1 was added to a 250mL pressure-resistant tube, followed by 100mL of water, 12.31g of mercaptopropionic acid, and 9.66g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen gas. The reaction was carried out at 135℃ for 7 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, and a large amount of solid precipitated out. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The mixture was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the filter cake was dried to obtain 25g of white solid B1, with a yield of 78.78%.

[0028] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 25 g of white solid B1 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 30 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 21.5 g of pale yellow solid C1, with a yield of 90.99%.

[0029] Under nitrogen protection, 14.75 g of pale yellow solid C1 was added to a reaction flask, along with 0.8 g of potassium iodide and 0.31 g of elemental iodine. Then, 50 mL of dimethyl sulfoxide was added, and the mixture was heated to 120 °C and reacted for 10 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 14 g of brown solid (D1) 8-(2,4,5-trimethylbenzoyl)-4H-thiochromene-4-one, with a yield of 95.56% and a purity of 99%. 1H-NMR (500 MHz, CDCl3) δ: 8.75 (d, J = 8.0 Hz, 1H), 7.84 (d, J = 10.5 Hz, 1H), 7.72 (d, J = 7.4 Hz, 1H), 7.47 (t, J = 7.7 Hz, 1H), 7.02 (s, 1H), 6.99 (d, J = 10.4 Hz, 1H), 6.97(s, 1H), 2.24 (s, 3H), 2.23 (s, 3H), 2.14 (s, 3H); 13 C-NMR (125 MHz, CDCl3) δ: 198.18, 179.36, 140.87, 140.64, 138.72, 136.14, 135.41, 135.35, 135.03,133.83, 133.79, 133.19, 132.87, 130.83, 126.31, 125.43, 60.39, 19.81, 19.78,19.18.

[0030] Example 2: Preparation of 8-benzoyl-4H-thiochromene-4-one

[0031] The reaction steps are as follows:

[0032] 15.6 g of benzene was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.95 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.7 g of o-chlorobenzoyl chloride was added dropwise, keeping the internal temperature below 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. After the reaction was monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from diethyl ether yielded 39.8 g of white solid A2, with a yield of 91.91%.

[0033] 20.78 g of white solid A2 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.7 g of mercaptopropionic acid, and 11.3 g of potassium hydroxide. Nitrogen gas was then introduced to replace the nitrogen atmosphere. The reaction was carried out at 120 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, resulting in the precipitation of a large amount of solid. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The cake was then slurried with diethyl ether for 2 hours, filtered, and the dried filter cake yielded 22.3 g of white solid B2, with a yield of 81.22%.

[0034] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 22.3 g of white solid B2 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 19.3 g of pale yellow solid C2, with a yield of 92.36%.

[0035] Under nitrogen protection, 12.65 g of pale yellow solid C2 was added to a reaction flask, along with 0.42 g of potassium iodide and 0.19 g of elemental iodine. Then, 40 mL of dimethyl sulfoxide was added, and the mixture was heated to 140 °C and reacted for 6 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 12.1 g of brown solid (D2) 8-benzoyl-4H-thiochromene-4-one, with a yield of 96.41% and a purity of 99%. 1 H-NMR (500 MHz, CDCl3) δ: 8.13 (dd, J =7.8, 1.2 Hz, 1H), 7.94 (dd, J = 7.6, 1.2 Hz, 1H), 7.76–7.70 (m, 2H), 7.63–7.46 (m, 5H), 6.80 (d, J = 7.8 Hz, 1H); 13 CN(125MHz, CDCl3) δ: 199.31, 183.77,144.05, 138.96, 137.20, 133.37, 133.00, 132.69, 132.57, 130.40, 129.69,128.73, 125.50, 125.27;

[0036] Example 3: Preparation of 8-(4-dimethylaminobenzoyl)-4H-thiochromene-4-one

[0037] The reaction steps are as follows:

[0038] 24.2 g of dimethylaminobenzene was added to a 250 ml dry three-necked flask, followed by 120 ml of dry petroleum ether. The mixture was then placed under nitrogen protection and cooled to 0 °C. 27 g of aluminum trichloride was added in portions. After the addition was complete, 31.75 g of o-fluorobenzoyl chloride was added dropwise while the internal temperature was kept below 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. The reaction was monitored by GC and then poured into ice water. Hydrochloric acid was added to adjust the pH to 2. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 45.3 g of white solid A3, with a yield of 93.2%.

[0039] 23.33 g of white solid A3 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.8 g of mercaptopropionic acid, and 9.7 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen gas. The reaction was carried out at 130 °C for 6 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, and a large amount of solid precipitated out. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The mixture was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 26.85 g of white solid B3, with a yield of 85.01%.

[0040] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 26.85 g of white solid B3 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 50 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 23.9 g of pale yellow solid C3, with a yield of 94.17%.

[0041] Under nitrogen protection, 14.8 g of pale yellow solid C3 was added to a reaction flask, along with 0.5 g of potassium iodide and 0.22 g of elemental iodine, and then 40 mL of dimethyl sulfoxide was added. The mixture was heated to 140 °C and reacted for 6 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 14.15 g of brown solid (D3) 8-(4-dimethylaminobenzoyl)-4H-thiochromene-4-one, with a yield of 96.26% and a purity of 99%. 1H-NMR (500 MHz, CDCl3) δ: 8.13 (dd, J = 7.8, 1.2 Hz, 1H), 7.94 (dd, J = 7.5, 1.1 Hz, 1H), 7.76–7.70 (m, 2H), 7.63–7.54 (m, 2H), 6.90–6.84 (m, 2H), 6.80 (d, J = 7.9 Hz, 1H), 2.98 (s, 6H); 13 C-NMR (125 MHz, CDCl3) δ: 199.07, 183.77, 153.16, 144.30, 138.96, 133.37,132.80, 132.57, 131.12, 130.40, 129.55, 125.50, 125.27, 111.67, 40.29;

[0042] Example 4: Preparation of 6-(2,3,5,6-tetramethylbenzoyl)-4H-thiochromene-4-one

[0043] The reaction steps are as follows:

[0044] 26.8 g of xylene was added to a 250 ml dry three-necked flask, followed by 120 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 0 °C. 26.9 g of aluminum trichloride was added in portions. After the addition was complete, and the temperature was lowered to 0 °C, 31.75 g of p-fluorobenzoyl chloride was added dropwise, keeping the internal temperature below 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. After the reaction was monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 48.2 g of white solid A4, with a yield of 94.14%.

[0045] 24.58 g of white solid A4 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.9 g of mercaptopropionic acid, and 9.8 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen gas. The reaction was carried out at 125 °C for 5 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, and a large amount of solid precipitated out. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The mixture was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 28.24 g of white solid B4, with a yield of 86%.

[0046] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 28.24 g of white solid B4 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 50 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 25.4 g of pale yellow solid C4, with a yield of 94.95%.

[0047] Under nitrogen protection, 15.45 g of pale yellow solid C4 was added to a reaction flask, along with 0.52 g of potassium iodide and 0.25 g of elemental iodine. Then, 45 mL of dimethyl sulfoxide was added, and the mixture was heated to 130 °C and reacted for 7 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 14.86 g of brown solid (D4)6-(2,3,5,6-tetramethylbenzoyl)-4H-thiochromene-4-one, with a yield of 96.81% and a purity of 99%. 1 H-NMR (500 MHz, CDCl3) δ: 8.14 (dd, J = 7.9, 1.1 Hz, 1H), 7.86 (dd, J = 7.6, 1.2 Hz, 1H), 7.62–7.54 (m,2H), 7.09–7.05 (m, 1H), 6.80 (d, J = 7.8 Hz, 1H), 2.23 (s, 6H).2.22 (s, 6H); 13 C-NMR (125 MHz, CDCl3) δ: 199.53, 183.77, 143.34, 139.03, 137.62, 135.57,133.99, 132.78, 132.62, 131.47, 131.21, 130.91, 125.48, 125.27, 20.36, 16.99;

[0048] Example 5: Preparation of 6-(4-methoxybenzoyl)-4H-thiochromene-4-one

[0049] The reaction steps are as follows:

[0050] 21.63 g of anisole was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.5 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.5 g of o-chlorobenzoyl chloride was added dropwise, maintaining the internal temperature no higher than 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. After the reaction was monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 45.4 g of white solid A5, with a yield of 92.03%.

[0051] 23.68 g of white solid A5 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.8 g of mercaptopropionic acid, and 11.3 g of potassium hydroxide. Nitrogen gas was then introduced to replace the nitrogen atmosphere. The reaction was carried out at 120 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, resulting in the precipitation of a large amount of solid. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The cake was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 25.5 g of white solid B5, with a yield of 84.02%.

[0052] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 25.5 g of white solid B5 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 22.4 g of pale yellow solid C5, with a yield of 93.15%.

[0053] Under nitrogen protection, 14.15 g of pale yellow solid C5 was added to a reaction flask, along with 0.6 g of potassium iodide and 0.25 g of elemental iodine, and then 45 mL of dimethyl sulfoxide was added. The mixture was heated to 125 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 13.48 g of brown solid (D5) 6-(4-methoxybenzoyl)-4H-thiochromene-4-one, with a yield of 95.94% and a purity of 99%. 1H-NMR (500 MHz, CDCl3) δ: 8.13 (dd, J = 7.8, 1.2 Hz, 1H), 7.94 (dd, J = 7.5, 1.1 Hz, 1H), 7.86–7.80 (m, 2H), 7.63–7.54 (m, 2H), 6.99–6.93 (m, 2H), 6.80 (d, J = 7.9 Hz, 1H), 3.83 (s, 3H); 13 C-NMR (125 MHz, CDCl3) δ: 198.95, 183.77, 163.48, 144.29, 138.96, 133.37,132.73, 132.57, 131.69, 131.32, 130.40, 125.50, 125.27, 114.15, 55.32;

[0054] Example 6: Preparation of 6-(4-phenylbenzoyl)-4H-thiochromene-4-one

[0055] The reaction steps are as follows:

[0056] 30.84 g of biphenyl was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.6 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.6 g of o-chlorobenzoyl chloride was added dropwise, maintaining the internal temperature no higher than 5 °C. The reaction was then maintained at 5-10 °C for two hours. After the reaction was complete as monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 54.4 g of white solid A6, with a yield of 92.94%.

[0057] 28.1 g of white solid A6 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.7 g of mercaptopropionic acid, and 9.8 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen atmosphere. The reaction was carried out at 145 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, resulting in the precipitation of a large amount of solid. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The cake was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 29.6 g of white solid B6, with a yield of 85.13%.

[0058] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 29.6 g of white solid B6 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 26.4 g of pale yellow solid C6, with a yield of 93.85%.

[0059] Under nitrogen protection, 16.45 g of pale yellow solid C6 was added to a reaction flask, along with 0.7 g of potassium iodide and 0.3 g of elemental iodine, and then 50 mL of dimethyl sulfoxide was added. The mixture was heated to 130 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 15.53 g of brown solid (D6) 6-(4-phenylbenzoyl)-4H-thiochromene-4-one, with a yield of 94.98% and a purity of 99%. 1 H-NMR (500 MHz, CDCl3) δ: 8.13 (dd,J = 7.8, 1.2 Hz, 1H), 7.94 (dd,J = 7.5, 1.1 Hz, 1H), 7.90–7.84 (m, 2H),7.72–7.66 (m, 2H), 7.63–7.54 (m, 4H), 7.48–7.41 (m, 2H), 7.44–7.34 (m, 1H), 6.80 (d, J = 7.8 Hz, 1H); 13 C-NMR (125 MHz, CDCl3) δ: 199.20, 183.77, 145.12,144.05, 139.50, 138.96, 136.90, 133.37, 132.75, 132.57, 130.57, 130.40,129.08, 127.90, 127.71, 127.34, 125.50, 125.27;

[0060] Example 7: Preparation of 6-(4-methylmercaptobenzoyl)-4H-thiochromene-4-one

[0061] The reaction steps are as follows:

[0062] 24.84 g of anisole was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.5 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.5 g of o-chlorobenzoyl chloride was added dropwise, maintaining the internal temperature no higher than 5 °C. The reaction was maintained at 5-10 °C for two hours. After GC monitoring, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 47.7 g of white solid A7, with a yield of 90.78%.

[0063] 25.22 g of white solid A7 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.8 g of mercaptopropionic acid, and 11.3 g of potassium hydroxide. Nitrogen gas was then added to replace the nitrogen atmosphere. The reaction was carried out at 120 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, resulting in the precipitation of a large amount of solid. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The cake was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 27.1 g of white solid B7, with a yield of 84.95%.

[0064] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 26.78 g of white solid B7 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 23.5 g of pale yellow solid C7, with a yield of 92.78%.

[0065] Under nitrogen protection, 14.9 g of pale yellow solid C7 was added to a reaction flask, along with 0.7 g of potassium iodide and 0.3 g of elemental iodine. Then, 50 mL of dimethyl sulfoxide was added, and the mixture was heated to 130 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 13.6 g of brown solid (D7) 6-(4-methylmercaptobenzoyl)-4H-thiochromene-4-one, with a yield of 91.89% and a purity of 99%. 1H-NMR (500 MHz, CDCl3) δ: 8.36 (d, J= 2.3 Hz, 1H), 7.96 (dd, J = 7.9, 2.2 Hz, 1H), 7.84-7.79 (m, 2H), 7.53 (d, J= 7.8 Hz, 1H), 7.49 (d, J = 7.9 Hz, 1H), 7.41-7.35 (m, 2H), 6.78 (d, J = 8.1Hz, 1H), 2.49 (s, 3H); 13 C-NMR (125 MHz, CDCl3) δ: 196.83, 179.96, 142.85, 141.95,138.20, 135.21, 134.96, 131.74, 130.04, 129.93, 128.76, 127.29, 125.83,125.29, 15.51;

[0066] Example 8: Preparation of 6-(4-methylselenobenzoyl)-4H-thiochromene-4-one

[0067] The reaction steps are as follows:

[0068] 34.22 g of benzoyl selenide was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.6 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.6 g of o-chlorobenzoyl chloride was added dropwise, keeping the internal temperature below 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. After the reaction was monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 55.9 g of white solid A8, with a yield of 90.28%.

[0069] 29.72 g of white solid A8 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.7 g of mercaptopropionic acid, and 9.8 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen gas. The reaction was carried out at 145 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, and a large amount of solid precipitated out. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The mixture was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 30.6 g of white solid B8, with a yield of 84.05%.

[0070] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 30.57 g of white solid B8 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 26.9 g of pale yellow solid C8, with a yield of 92.38%.

[0071] Under nitrogen protection, 17.12 g of pale yellow solid C6 was added to a reaction flask, along with 0.7 g of potassium iodide and 0.3 g of elemental iodine, and then 50 mL of dimethyl sulfoxide was added. The mixture was heated to 130 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 15.6 g of brown solid (D8) 6-(4-methylselenobenzoyl)-4H-thiochromene-4-one, with a yield of 91.6% and a purity of 99%. 1 H-NMR (500 MHz, CDCl3) δ: 8.36 (d, J= 2.3 Hz, 1H), 7.96 (dd, J = 7.9, 2.2 Hz, 1H), 7.80-7.74 (m, 2H), 7.68-7.62(m, 2H), 7.53 (d, J = 7.8 Hz, 1H), 7.49 (d, J = 7.9 Hz, 1H), 6.78 (d, J = 8.1Hz, 1H), 2.58 (s, 3H); 13 C-NMR (125 MHz, CDCl3) δ: 196.36, 179.96, 142.85, 138.20,135.79, 135.00, 134.80, 131.74, 131.01, 130.83, 130.04, 128.76, 125.83,125.29, 7.59;

[0072] Example 9: Preparation of 6-(4-trimethylsilylbenzoyl)-4H-thiochromen-4-one

[0073] The reaction steps are as follows:

[0074] 30.06 g of phenyltrimethylsilane was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.6 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.6 g of o-chlorobenzoyl chloride was added dropwise, maintaining the internal temperature no higher than 5 °C. The reaction was maintained at 5-10 °C for two hours. After the reaction was complete as monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 53.6 g of white solid A9, with a yield of 92.8%.

[0075] 27.72 g of white solid A9 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.7 g of mercaptopropionic acid, and 9.8 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen atmosphere. The reaction was carried out at 145 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, resulting in the precipitation of a large amount of solid. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The cake was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 28.9 g of white solid B9, with a yield of 83.99%.

[0076] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 28.9 g of white solid B9 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was completed by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 25.4 g of pale yellow solid C9, with a yield of 92.56%.

[0077] Under nitrogen protection, 16.14 g of pale yellow solid C9 was added to a reaction flask, along with 0.7 g of potassium iodide and 0.3 g of elemental iodine, and then 50 mL of dimethyl sulfoxide was added. The mixture was heated to 130 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 14.5 g of brown solid (D9) 6-(4-trimethylsilylbenzoyl)-4H-thiochromene-4-one, with a yield of 90.39% and a purity of 99%. 1H-NMR (500 MHz, CDCl3) δ: 8.36 (d, J = 2.3 Hz, 1H), 7.96 (dd, J = 7.9, 2.2 Hz, 1H), 7.72-7.66 (m, 2H), 7.66-7.60 (m, 2H), 7.53 (d, J = 7.8 Hz, 1H), 7.49 (d, J = 7.9 Hz, 1H), 6.78 (d, J= 8.1 Hz, 1H), 0.42 (s, 9H); 13 C-NMR (125 MHz, CDCl3) δ: 196.36, 179.96, 143.45,142.85, 138.20, 137.55, 135.00, 132.74, 131.74, 130.04, 129.47, 128.76,125.83, 125.29, -1.22.

[0078]

[0079] Example 10: Preparation of 6-(4-acetoxybenzoyl)-4H-thiochromene-4-one

[0080] The reaction steps are as follows:

[0081] 27.23 g of phenyl acetate was added to a 250 ml dry three-necked flask, followed by 100 ml of dry dichloromethane. The mixture was then placed under nitrogen protection and cooled to 5 °C. 27.6 g of aluminum trichloride was added in portions. After the addition was complete, the temperature was lowered to 0 °C, and 36.6 g of o-chlorobenzoyl chloride was added dropwise, maintaining the internal temperature no higher than 5 °C. The reaction was maintained at 5-10 °C for two hours after the addition was complete. After the reaction was monitored by GC, the mixture was poured into ice water, and the pH was adjusted to 2 with hydrochloric acid. The mixture was separated, and the organic phase was washed with saturated sodium bicarbonate, water, and saturated brine. The organic phase was dried and concentrated to dryness. Recrystallization from methyl tert-butyl ether yielded 50.3 g of white solid A10, with a yield of 91.57%.

[0082] 26.37 g of white solid A10 was added to a 250 mL pressure-resistant tube, followed by 100 mL of water, 11.7 g of mercaptopropionic acid, and 9.8 g of sodium hydroxide. Nitrogen gas was then added to replace the nitrogen gas. The reaction was carried out at 145 °C for 8 hours. After the reaction was completed, the pH was adjusted to 3 with hydrochloric acid, and a large amount of solid precipitated out. The mixture was stirred for another half hour, filtered, and the filter cake was dried. The mixture was then slurried with methyl tert-butyl ether for 2 hours, filtered, and the dried filter cake yielded 27.7 g of white solid B10, with a yield of 83.81%.

[0083] 50 mL of concentrated sulfuric acid was added to a 100 mL reaction flask, and the temperature was lowered to 10 °C. Then, 27.7 g of white solid B10 was added in portions. After the addition was complete, the mixture was stirred at room temperature for half an hour, and then heated to 40 °C for 5 hours. After the reaction was complete as detected by TLC, the reaction solution was slowly poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, and then slurryed with methanol to obtain 23.7 g of pale yellow solid C10, with a yield of 90.11%.

[0084] Under nitrogen protection, 15.47 g of pale yellow solid C10 was added to a reaction flask, along with 0.7 g of potassium iodide and 0.3 g of elemental iodine. Then, 50 mL of dimethyl sulfoxide was added, and the mixture was heated to 130 °C and reacted for 8 hours. The reaction was confirmed to be complete by TLC. The reaction solution was then poured into ice water, and a large amount of solid precipitated. The solid was filtered, the filter cake was washed with water, slurried with methanol, and filtered to obtain 13.9 g of brown solid (D10) 6-(4-acetoxybenzoyl)-4H-thiochromene-4-one, with a yield of 90.44% and a purity of 99%. 1 H-NMR (500 MHz, CDCl3) δ: 8.36(d, J = 2.3 Hz, 1H), 7.96 (dd, J = 7.9, 2.2 Hz, 1H), 7.89-7.83 (m, 2H), 7.53(d, J = 7.8 Hz, 1H), 7.49 (d, J = 7.9 Hz, 1H), 7.38-7.32 (m, 2H), 6.78 (d, J= 8.1 Hz, 1H), 2.28 (s, 3H); 13 C-NMR (125 MHz, CDCl3) δ: 196.47, 179.96, 169.20,154.19, 142.85, 138.20, 134.97, 132.91, 131.91, 131.74, 130.04, 128.76,125.83, 125.29, 122.12, 21.10.

[0085] Application Example 1: Evaluation of the photoinitiating performance of novel photoinitiators D1-D10 containing polymerizable groups

[0086] UV-curable ink samples were prepared using novel photoinitiators D1-D10 containing polymerizable groups prepared in Examples 1-10 as photoinitiators. The method is as follows: The following components were prepared by mass: 71% UV ink prepolymer (a mixture of rosin-modified epoxy acrylate and bis(trimethylolpropane)tetraacrylate in a mass ratio of 1:1), 20% carbon black, 4% wax powder, 2% kaolin, and 3% of novel photoinitiators D1-D10 containing polymerizable groups. The mixture was then finely dispersed three times using a three-roll mill to obtain UV-curable ink samples E1-E10 with a fineness of ⩽12.5 μm.

[0087] UV-curable ink samples were prepared using the traditional photoinitiator 2,4-diethylthioxanthonone (DETX) as the photoinitiator. The method is as follows: the 3% of the novel photoinitiator D1-D10 containing polymerizable groups in the above method was replaced with 3% of the traditional photoinitiator 2,4-diethylthioxanthonone (DETX), while the proportions of other raw materials remained unchanged, and UV-curable ink sample F was prepared.

[0088] Performance tests were conducted on samples E1-E10 and sample F for comparison: Following the method described in "CY / T127-2015 Preparation Method of Test Samples for Volatile Organic Compounds in Printing Materials for Paper Printing," printing samples were obtained by developing color on 128 g / m² coated paper. These samples were then cured under a UV lamp with a power density of 10 W / cm² to obtain coated paper prints. The completion of photopolymerization curing was determined by the absence of any marks produced when repeatedly pressed and scratched with a fingernail. The results showed that samples E1-E10 and sample F had similar curability, adhesion, and gloss. Therefore, it was indicated that the curing speed of the novel photoinitiators D1-D10 containing polymerizable groups prepared in this invention did not show any difference from that of photoinitiator DETX.

[0089] Application Example 2: Migration Comparison Experiment.

[0090] Further testing of the alcohol resistance of the photoinitiator was conducted on coated paper printed materials prepared in Application Example 1. The method involved immersing the coated paper printed materials in a 20% (v / v) alcohol solution for 1–13 days, and testing specific migration characteristics on days 1, 5, 9, and 13. The migration test results are shown in Table 1, where N and D represent no migration. The migration test followed GB31604.1-2015.

[0091] Table 1 Results of alcohol migration test

[0092] The alcohol resistance test results show that samples E1-E10 showed no migration, while sample F showed a migration rate of 1.17 mg / m³ on the 13th day of immersion. 2 Therefore, it can be concluded that samples E1-E10 have better resistance to alcohol migration than sample F.

[0093] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A photoinitiator containing an unsaturated carbon-carbon double bond within a sulfur-containing heterocyclic ring, characterized in that, The structure is shown in equation (I) or equation (II): （I） （Ⅱ）； Where R n For single or multiple substitutions on the benzene ring, R n It is selected from one of hydrogen atom, alkyl, N-alkyl, O-alkyl, S-alkyl, Se-alkyl, Si-alkyl, aromatic cycloyl, and acyloxy group.

2. The photoinitiator according to claim 1, characterized in that, The alkyl group is a C1-C5 alkyl group.

3. The method for preparing the photoinitiator according to claim 1, characterized in that, Includes the following steps: S1: Benzene compounds were dissolved in an organic solvent. Aluminum trichloride was added in batches at 0-5℃ under nitrogen protection. Halogenated benzoyl chloride was added dropwise while maintaining the low temperature at 0-5℃. The reaction was kept at this temperature. After the reaction was completed by GC monitoring, the mixture was poured into ice water. Hydrochloric acid was added to adjust the pH to 2. The mixture was separated into liquid and liquid phases. The organic phase was post-treated and recrystallized with an ether solvent to obtain a white solid A. ； X is selected from F, Cl, and Br, and X is substituted at the ortho or para position. S2: Add the white solid A obtained in step S1 to the pressure-resistant tube, add water, mercaptopropionic acid, inorganic base, replace nitrogen gas, react at 120-150℃, monitor the reaction by TLC, adjust the pH to 3 with hydrochloric acid, a large amount of solid precipitates out, continue stirring, filter, dry the filter cake, slurry with ether solvent for 2 hours, filter, dry the filter cake to obtain white solid B. ； S3: Add concentrated sulfuric acid to the reaction flask, cool to 10°C, and then add the white solid B obtained in step S2 in batches. After the addition is complete, stir at room temperature, and then heat to 30-50°C to react. After the reaction is complete, TLC is used to detect the reaction. Then slowly pour the reaction solution into ice water to precipitate the solid. Filter, wash the filter cake with water, and then slurry with methanol to obtain a slightly yellow solid C. S4: Under nitrogen protection, add the pale yellow solid C obtained in step S3 to the reaction flask, add potassium iodide and elemental iodine, then add dimethyl sulfoxide, heat to 120-140℃ and react. TLC detects that the reaction is complete. Pour the reaction solution into ice water to precipitate the solid, filter, wash the filter cake with water, slurry with methanol, filter, and obtain brown solid D. 。 4. The preparation method according to claim 3, characterized in that, In step S1, the molar ratio of benzene compounds, aluminum trichloride, and halogenated benzoyl chloride is 1:1-1.05:1-1.05; the organic solvent is selected from one or two of dichloromethane, dichloroethane, chloroform, n-hexane, cyclohexane, and petroleum ether; the post-treatment of the organic phase includes the following steps: the organic phase is washed with saturated sodium bicarbonate, washed with water, washed with saturated brine, dried, and concentrated to dryness; the ether solvent is selected from one or two of methyl tert-butyl ether, diethyl ether, methyl ethyl ether, and propyl ether.

5. The preparation method according to claim 3, characterized in that, In step S2, the molar ratio of white solid A, mercaptopropionic acid, and inorganic base is 1:1.14-1.25:2.08-2.6; the inorganic base is selected from sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate; the reaction time is 5-9 hours; and the ether solvent is selected from one or two of methyl tert-butyl ether, diethyl ether, methyl ethyl ether, and propyl ether.

6. The preparation method according to claim 3, characterized in that, In step S3, the molar ratio of concentrated sulfuric acid to white solid B is 1-1.1:

1.

7. The preparation method according to claim 3, characterized in that, In step S4, the molar ratio of potassium iodide, elemental iodine, and pale yellow solid C is 0.05-0.1:0.015-0.025:1; the reaction time is 6-10 h.

8. The use of the photoinitiator according to claim 1 in the preparation of ink.

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