A photosensitizer and its preparation method and application

Abstract

The present invention relates to the technical field of organic chemicals, and in particular to a photosensitizer and a preparation method and application thereof. The structure of the photosensitizer is shown in formula (I). The photosensitizer of the present invention has no irritating odor, good curing property and adhesion, and lower biological toxicity.

Description

Technical Field

[0001] The present invention relates to the technical field of organic chemicals, and in particular to a photosensitizer and a preparation method and application thereof. Background Art

[0002] Photosensitizers are also called photoinitiators, which are roughly divided into free radical type and ionic type. The former is used to initiate the polymerization of vinyl functional groups, and is further divided into two categories: direct cleavage type and hydrogen abstraction type. α-substituted acetophenone and acylphosphine oxide are representative direct cleavage type photoinitiators, and benzophenone and thioxanthone are representative hydrogen abstraction type photoinitiators. Chinese invention patent CN1281577C discloses a photosensitive quaternary ammonium salt, which can generate free radicals and tertiary amines after photolysis, and is a quaternary ammonium salt of aromatic ketone based on dialkylamine. These initiators all have the disadvantage of high toxicity.

[0003] In recent years, a large number of photoinitiators have been banned due to toxicity or reproductive toxicity, so the design and development of new photosensitizers have received increasing attention.

[0004] Currently, the photosensitizer commonly used in coatings and inks is benzophenone, which has two main defects: first, it will leave a strong and unpleasant pungent smell of benzophenone on the product after use, causing consumers to suffer from residual odor; second, it has high biological toxicity and poor curing and adhesion.

[0005] Therefore, it is very necessary to develop a photosensitizer and a preparation method and application thereof that can solve the above technical problems. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a photosensitizer with no irritating odor, good curing and adhesion, and lower biological toxicity, as well as a preparation method and application thereof.

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

[0008] The first aspect of the present invention provides a photosensitizer, the chemical name of which is 2,4,6-trimethyl-4'-diethylaminobenzophenone, and the structure is shown in formula (I):

[0009] (I).

[0010] The second aspect of the present invention provides a method for preparing the photosensitizer, comprising the following steps:

[0011] S1: Add anhydrous aluminum chloride, organic solvent A and 2,4,6-trimethylbenzoyl chloride to a reaction flask, add N,N-diethylaniline under stirring, heat to reflux for reaction, add the reaction solution to a hydrochloric acid aqueous solution, extract with organic solvent A, wash the extracted organic phase A with saturated sodium bicarbonate solution, water and saturated brine in sequence, and dry to obtain an organic phase B;

[0012] S2: Filter the organic phase B to remove the organic solvent A to obtain a brown-yellow oil, add a non-polar organic solvent, stir to obtain a solid C, and then wash with a mixed solvent or recrystallize to obtain;

[0013] The reaction formula is as follows:

[0014] .

[0015] In some embodiments of the present invention, in step S1, the organic solvent A is selected from one or more of dichloromethane, chloroform, 1,2-dichloroethane, carbon tetrachloride, and 1,1-dichloroethane, preferably dichloromethane.

[0016] In some embodiments of the present invention, in step S1, the mass ratio of the volume of the organic solvent A to the 2,4,6-trimethylbenzoyl chloride is 3-5 mL:1 g.

[0017] In some embodiments of the present invention, in step S1, the molar ratio of anhydrous aluminum chloride, 2,4,6-trimethylbenzoyl chloride and N,N-diethylaniline is 1.01-1.5:1:1.01-2.5.

[0018] In some embodiments of the present invention, in step S1, the reflux reaction time is 12h-24; the mass concentration of the hydrochloric acid aqueous solution is 10-15%, and the temperature is -5~5°C.

[0019] In some embodiments of the present invention, in step S1, organic solvent A is used for extraction three times, and the organic phases are combined to obtain organic phase A.

[0020] In some embodiments of the present invention, in step S1, the saturated sodium bicarbonate solution is washed to a weak alkalinity.

[0021] In some embodiments of the present invention, in step S1, drying is performed using anhydrous sodium sulfate.

[0022] In some embodiments of the present invention, in step S2, the organic solvent A is removed by vacuum rotary evaporation.

[0023] In some embodiments of the present invention, in step S2, the non-polar organic solvent is selected from one or both of petroleum ether and cyclohexane.

[0024] In some embodiments of the present invention, in step S2, the mixed solvent consists of solvent 1 and solvent 2, solvent 1 is selected from one of petroleum ether and cyclohexane, solvent 2 is selected from one of ethyl acetate, dichloromethane and methanol, and the mixed solvent is specifically selected from one of petroleum ether / ethyl acetate, cyclohexane / ethyl acetate, petroleum ether / dichloromethane, cyclohexane / dichloromethane, petroleum ether / methanol, and cyclohexane / methanol. The volume ratio of solvent 1 to solvent 2 is 1-50:1.

[0025] The third aspect of the present invention provides a method for preparing the photosensitizer, comprising the following steps:

[0026] (1) Add anhydrous aluminum chloride and organic solvent D to a reaction flask, add 4-chlorobenzoyl chloride at -5~5°C, stir and react for 0.5-1h, then add 1,3,5-trimethylbenzene, continue to react at 10-25°C for 1-3h, add the reaction solution to a hydrochloric acid aqueous solution, extract with organic solvent D, wash the extracted organic phase D with saturated sodium bicarbonate solution, water and saturated brine in sequence, and dry to obtain an organic phase E;

[0027] (2) Filter the organic phase E to remove the organic solvent D to obtain a solid F, then add a polar organic solvent, diethylamine and an inorganic alkaline compound to the solid F, react at a certain temperature, cool to room temperature after the reaction, add water to precipitate the solid, and then wash with petroleum ether to obtain;

[0028] The reaction formula is as follows:

[0029] .

[0030] In some embodiments of the present invention, the molar ratio of anhydrous aluminum chloride, 4-chlorobenzoyl chloride and 1,3,5-trimethylbenzene in step (1) is 1-2:1:1-3.

[0031] In some embodiments of the present invention, the organic solvent D in step (1) is selected from one or more of chloroform, dichloromethane, and 1,2-dichloroethane; the mass concentration of the hydrochloric acid aqueous solution is 10-15%, and the temperature is -5~5°C.

[0032] In some embodiments of the present invention, in step (2), the polar organic solvent is selected from one or two of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; the inorganic alkaline compound is selected from one or two of potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide; the temperature is 100-200° C., and the reaction time is 12-24 h.

[0033] In some embodiments of the present invention, the molar ratio of 4-chlorobenzoyl chloride, diethylamine, and the inorganic alkaline compound is 1:1-3:1-2.

[0034] In some embodiments of the present invention, the usage ratio of 4-chlorobenzoyl chloride and polar organic solvent is 1 mol: 50-100 mL.

[0035] The fourth aspect of the present invention provides the use of a photosensitizer in the preparation of ink, which is mainly used in the field of ink.

[0036] The beneficial effects of the present invention are:

[0037] Compared with the photosensitizer benzophenone in traditional inks, the photosensitizer 2,4,6-trimethyl-4'-diethylaminobenzophenone of the present invention has lower toxicity, no irritating odor, and better ultraviolet absorption, curing and adhesion performance. Compared with tetramethyl Michler's ketone / tetraethyl Michler's ketone, the photosensitizer 2,4,6-trimethyl-4'-diethylaminobenzophenone has lower biological toxicity and comparable ultraviolet absorption, curing and adhesion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the H NMR spectrum of the product prepared in Example 1.

[0039] Figure 2 This is the H NMR spectrum of the product prepared in Example 4. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with specific embodiments, and the advantages and features of the present invention will become clearer as the description proceeds. However, these embodiments are exemplary only and do not constitute any limitation to the scope of the present invention. It should be understood by those skilled in the art that the details and forms of the technical solution of the present invention may be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the scope of protection of the present invention.

[0041] The "eq" in the examples of the present invention represents the amount equivalent of a substance.

[0042] Example 1

[0043] The preparation of 2,4,6-trimethyl-4'-diethylaminobenzophenone is as follows:

[0044] .

[0045] Add 1.01eq of anhydrous aluminum chloride, 50mL of dichloromethane and 1.0eq of 2,4,6-trimethylbenzoyl chloride to the reaction flask, add 1.01eq of N,N-diethylaniline under stirring, and heat under reflux for 12h. After the reaction is completed, slowly add the reaction solution dropwise to a 15wt% hydrochloric acid aqueous solution at -5°C, extract with dichloromethane three times, combine the organic phases, wash with saturated NaHCO3 solution until weakly alkaline, wash with purified water, wash with saturated brine, and dry with anhydrous sodium sulfate.

[0046] The organic phase obtained after drying was filtered, and the solvent was removed by rotary evaporation under reduced pressure to obtain a brown-yellow oil with a yield of 87%. Petroleum ether was added to the brown-yellow oil and stirred to obtain a light yellow powder solid with a crude yield of 83%. It was then washed with petroleum ether: ethyl acetate = 30:1. A light yellow product that met the standards was obtained with a yield of 70% and a purity of 99.03%.

[0047] H NMR spectrum Figure 1 .

[0048] Mass Spectrometry Data:

[0049] C 20 H 25 NO: LCMS-IT-TOF high resolution mass spectrometry measured [M+H]+: 296.1997, theoretical value 296.2009.

[0050] Example 2

[0051] The preparation of 2,4,6-trimethyl-4'-diethylaminobenzophenone is as follows:

[0052] .

[0053] Add 1.2eq of anhydrous aluminum chloride, 50mL of 1,2-dichloroethane and 1.0eq of 2,4,6-trimethylbenzoyl chloride to the reaction flask, add 1.5eq of N,N-diethylaniline under stirring, and heat under reflux for 24h. After the reaction is completed, slowly add the reaction solution dropwise to a 10wt% hydrochloric acid aqueous solution at 0°C, extract three times with 1,2-dichloroethane, combine the organic phases, wash with saturated NaHCO3 solution until weakly alkaline, wash with pure water, wash with saturated brine, and dry with anhydrous sodium sulfate.

[0054] The organic phase obtained after drying was filtered and the solvent was removed by rotary evaporation under reduced pressure to obtain a brown-yellow oil with a yield of 89%. Cyclohexane was added to the brown-yellow oil and stirred to obtain a light yellow powder solid with a crude yield of 85%. It was then washed with cyclohexane: ethyl acetate = 45:1. A light yellow product that met the standard was obtained with a yield of 73%.

[0055] Example 3

[0056] The preparation of 2,4,6-trimethyl-4'-diethylaminobenzophenone is as follows:

[0057] .

[0058] Add 1.5eq of anhydrous aluminum chloride, 50mL of chloroform and 1.0eq of 2,4,6-trimethylbenzoyl chloride to the reaction flask, add 2.5eq of N,N-diethylaniline under stirring, and heat under reflux for 12h. After the reaction is completed, slowly add the reaction solution dropwise to a 15wt% hydrochloric acid aqueous solution at 5°C, extract with chloroform three times, combine the organic phases, wash with saturated NaHCO3 solution until weakly alkaline, wash with purified water, wash with saturated brine, and dry with anhydrous sodium sulfate.

[0059] The organic phase obtained after drying was filtered and the solvent was removed by rotary evaporation under reduced pressure to obtain a brown-yellow oil with a yield of 84%. Petroleum ether was added to the brown-yellow oil and stirred to obtain a light yellow powder solid with a crude yield of 82%. It was then washed with petroleum ether: dichloromethane = 20:1. A light yellow product that met the standard was obtained with a yield of 71%.

[0060] Example 4

[0061] The preparation of 2,4,6-trimethyl-4'-diethylaminobenzophenone is as follows:

[0062] .

[0063] Add 1.0 eq of anhydrous aluminum chloride and 50 mL of chloroform to the reaction bottle, add 1.0 eq of 4-chlorobenzoyl chloride at -5°C, stir and react for 0.5 h, then add 1.0 eq of 1,3,5-trimethylbenzene, raise the temperature to 10°C, and continue the reaction for 1 h. After the reaction is completed, slowly add the reaction solution dropwise into a 10 wt% hydrochloric acid aqueous solution at -5°C, extract three times with chloroform, combine the organic phases, wash with saturated NaHCO3 solution until weakly alkaline, wash with pure water, wash with saturated brine, and dry with anhydrous sodium sulfate.

[0064] The organic phase obtained after drying was filtered, and the solvent was removed by rotary evaporation under reduced pressure to obtain a yellow powder solid with a yield of 90%. 50 mL of N, N-dimethylformamide, 1.0 eq of diethylamine and 1.0 eq of K2CO3 were added to the solid, and heated to 100 ° C for 12 hours. Cooled to room temperature, 200 mL of water was added to it, and the solid was precipitated. It was filtered to obtain a light yellow powder solid, and then washed with 200 mL of petroleum ether to obtain a light yellow product that meets the standard, with a yield of 75%. The H NMR spectrum is shown in Figure 2 .

[0065] Example 5

[0066] The preparation of 2,4,6-trimethyl-4'-diethylaminobenzophenone is as follows:

[0067] .

[0068] Add 2.0 eq of anhydrous aluminum chloride and 100 mL of dichloromethane to the reaction bottle, add 1.0 eq of 4-chlorobenzoyl chloride at 5°C, stir and react for 1 hour, then add 3.0 eq of 1,3,5-trimethylbenzene, raise the temperature to 25°C, and continue the reaction for 3 hours. After the reaction is completed, slowly add the reaction solution dropwise into a 15 wt% hydrochloric acid aqueous solution at 5°C, extract three times with dichloromethane, combine the organic phases, wash with saturated NaHCO3 solution until weakly alkaline, wash with pure water, wash with saturated brine, and dry with anhydrous sodium sulfate.

[0069] The organic phase obtained after drying was filtered, and the solvent was removed by rotary evaporation under reduced pressure to obtain a yellow powdery solid with a yield of 92%. 100 mL of N-methylpyrrolidone, 3.0 eq of diethylamine and 2.0 eq of KOH were added to the solid, and heated to 200 ° C for 24 h. The temperature was lowered to room temperature, 200 mL of water was added thereto, and a solid was precipitated, which was filtered to obtain a light yellow powdery solid, and then washed with 200 mL of petroleum ether to obtain a light yellow product that met the standards, with a yield of 78%.

[0070] Comparative Example 1

[0071] A comparative experiment on the photoinitiating performance of the 2,4,6-trimethyl-4'-diethylaminobenzophenone photosensitizer of Example 1 and benzophenone.

[0072] The following were prepared in mass percentage: UV ink prepolymer (a mixture of glycidyl acrylate and ditrimethylolpropane tetraacrylate, in a ratio of 99:1) 70%, TPO-L (ethyl 2,4,6-trimethylbenzoylphenylphosphonate) 3%, DETX (2,4-diethylthioxanthone) 3%, paraffin powder 4%, kaolin 2.5%, carbon black 15% and 2,4,6-trimethyl-4'-diethylaminobenzophenone 2.5%; after three passes of fine dispersion on a three-roll mill, a UV light-curing ink sample A with a fineness of ⩽12.5 μm was obtained.

[0073] A comparative sample was prepared according to the above method, wherein 2,4,6-trimethyl-4'-diethylaminobenzophenone was replaced with an equal mass of traditional photoinitiator benzophenone, and the proportions of other raw materials remained unchanged, to obtain UV light curing ink sample B.

[0074] Performance test comparison of sample A and sample B: refer to "CY / T 127-2015 Preparation method of volatile organic compound test samples for printed materials used in paper printed products", sample A or sample B is placed at 100g / m 2 Printing samples were obtained on offset paper (ink thickness 30μm) with a power density of 10W / cm 2 The ink was cured under the irradiation of LED-UV lamp to obtain a printed product containing the ink sample for migration test.

[0075] Referring to GB 31604.1-2023 National Food Safety Standard General Rules for Migration Test of Food Contact Materials and Articles, the printed matter to be tested containing the ink sample was immersed in a 20% (volume fraction) alcohol solution for 1-12 days to test its specific migration. Compared with the result of sample B (using the traditional photoinitiator benzophenone), sample A containing the photosensitizer 2,4,6-trimethyl-4'-diethylaminobenzophenone of the present invention has lower migration. The migration test results are shown in Table 1.

[0076] Table 1 Alcohol migration test results (migration mg / m 2 )

[0077]

[0078] According to the migration data in Table 1, sample A has lower migration, which means that it has better curing effect, stronger adhesion, lower extractables in alcohol, and better alcohol resistance.

[0079] Comparative Example 2

[0080] A comparative experiment on the cytotoxicity of the novel photosensitizer 2,4,6-trimethyl-4'-diethylaminobenzophenone (sample D) of Example 1 and tetraethyl Michler's ketone (sample C).

[0081] Two 96-well plates were used to culture Hek293 cells and Hek293T cells respectively. The culture medium was 10% fbs-DMEM. Then, samples C and D with different concentration gradients (0µM, 1µM, 5µM, 25µM, 125µM, 625µM, 3125µM) were added. After waiting for 24 hours, the CCK8 kit was used to detect the cell survival rate at different concentrations, and then the IC 50 value.

[0082] Sample D and sample C were subjected to a biological toxicity comparison experiment: compared with the result of sample C (using the photoinitiator tetraethyl Michler's ketone), sample D containing the photosensitizer 2,4,6-trimethyl-4'-diethylaminobenzophenone of the present invention has lower toxicity. The specific experimental results are shown in Table 2.

[0083] Table 2 Cytotoxicity comparison experiment

[0084]

[0085] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A photosensitizer, characterized in that: The structure is shown in formula (I): （I）。 2. The method for preparing a photosensitizer according to claim 1, characterized in that: The steps include: S1: Add anhydrous aluminum chloride, organic solvent A and 2,4,6-trimethylbenzoyl chloride to a reaction flask, add N,N-diethylaniline under stirring, heat to reflux for reaction, add the reaction solution to a hydrochloric acid aqueous solution, extract with organic solvent A, wash the extracted organic phase A with saturated sodium bicarbonate solution, water and saturated brine in sequence, and dry to obtain an organic phase B; S2: Filter the organic phase B to remove the organic solvent A to obtain a brown-yellow oil, add a non-polar organic solvent, stir to obtain a solid C, and then wash with a mixed solvent or recrystallize to obtain; The reaction formula is as follows: 。 3. The preparation method according to claim 2, characterized in that: In step S1, the reflux reaction time is 12h-24h; the mass concentration of the hydrochloric acid aqueous solution is 10-15%, and the temperature is -5~5°C; the organic solvent A is selected from one or more of dichloromethane, chloroform, 1,2-dichloroethane, carbon tetrachloride, and 1,1-dichloroethane; and the molar ratio of anhydrous aluminum chloride, 2,4,6-trimethylbenzoyl chloride, and N,N-diethylaniline is 1.01-1.5:1:1.01-2.

5.

4. The preparation method according to claim 2, characterized in that: In step S2, the non-polar organic solvent is selected from one or both of petroleum ether and cyclohexane; the mixed solvent consists of solvent 1 and solvent 2, solvent 1 is selected from one of petroleum ether and cyclohexane, solvent 2 is selected from one of ethyl acetate, dichloromethane and methanol, and the volume ratio of solvent 1 to solvent 2 is 1-50:

1.

5. The method for preparing a photosensitizer according to claim 1, characterized in that: The steps include: (1) Add anhydrous aluminum chloride and organic solvent D to a reaction flask, add 4-chlorobenzoyl chloride at -5~5°C, stir and react for 0.5-1h, then add 1,3,5-trimethylbenzene, continue to react at 10-25°C for 1-3h, add the reaction solution to a hydrochloric acid aqueous solution, extract with organic solvent D, wash the extracted organic phase D with saturated sodium bicarbonate solution, water and saturated brine in sequence, and dry to obtain an organic phase E; (2) Filter the organic phase E to remove the organic solvent D to obtain a solid F, then add a polar organic solvent, diethylamine and an inorganic alkaline compound to the solid F, react at a certain temperature, cool to room temperature after the reaction, add water to precipitate the solid, and then wash with petroleum ether to obtain; The reaction formula is as follows: 。 6. The preparation method according to claim 5, characterized in that: In step (1), the molar ratio of anhydrous aluminum chloride, 4-chlorobenzoyl chloride and 1,3,5-trimethylbenzene is 1-2:1:1-3; the organic solvent D is selected from one or more of chloroform, dichloromethane and 1,2-dichloroethane; the mass concentration of the hydrochloric acid aqueous solution is 10-15%, and the temperature is -5~5°C.

7. The preparation method according to claim 5, characterized in that: In step (2), the polar organic solvent is selected from one or two of N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; and the inorganic alkaline compound is selected from one or two of potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide.

8. The preparation method according to claim 5, characterized in that: The reaction temperature in step (2) is 100-200°C and the reaction time is 12-24h.

9. The preparation method according to claim 5, characterized in that: The molar ratio of 4-chlorobenzoyl chloride, diethylamine and inorganic alkaline compound is 1:1-3:1-2; the molar ratio of 4-chlorobenzoyl chloride and polar organic solvent is 1 mol: 50-100 mL.

10. Use of the photosensitizer according to claim 1 in preparing ink.

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