Chemical structure and preparation method of a class of phosphorus-containing photoinitiators containing hydroxyl or substituted amino structure

Abstract

The present application belongs to the field of fine chemicals and new materials, and relates to a high-efficiency preparation method of a phosphorus acyl photoinitiator, which is prepared by reacting TPO as a raw material with polyformaldehyde in a solvent under the action of aluminum trichloride, and then hydrolyzing or reacting with different primary amines or secondary amines. The structure has better optical activity than TPO, avoids the ban of the European Union on the TPO structure, and can effectively replace TPO in the market.

Description

[Technical Field]

[0001] This invention belongs to the field of fine chemical new materials. Using TPO as a raw material, a chloromethylated intermediate is obtained by reacting it with paraformaldehyde and aluminum trichloride in a solvent. Then, it is reacted with different primary or secondary amines or directly or partially hydrolyzed to achieve the efficient preparation of a class of phosphoryl photoinitiators. This structure has better optical activity than TPO, while circumventing the EU ban on TPO structures, and can effectively replace the TPO market. [Background Technology]

[0002] Photoinitiators are substances that absorb external light energy and undergo physicochemical changes to initiate polymerization reactions in other active substances within the system. They are typically added in very small amounts to the polymerization system, ranging from one-thousandth to three percent. Numerous photoinitiators are now widely used. Based on their photoinitiated polymerization mechanisms, they can be broadly classified into two categories: free radical and ionic. Free radical photoinitiators are further divided into cleavage-type and hydrogen-abstraction-type photoinitiators, while ionic photoinitiators are primarily cationic initiators.

[0003] TPO (2,4,6-trimethylbenzoyl)phosphine oxide is a highly efficient free radical LED photoinitiator. Due to its wide absorption range, with effective absorption peaks at 269nm, 298nm, and 379nm, extending to around 420nm, its absorption peak is longer than that of conventional initiators. Upon irradiation, it generates two free radicals, benzoyl and phosphoryl, both of which can initiate polymerization, resulting in rapid photocuring. It also possesses photobleaching properties, making it suitable for deep curing of thick films and preventing yellowing of coatings. With low volatility, it is ideal for deep curing of water-based LED photocurable coating systems. This product is primarily used in white systems and can also be used in UV-curable coatings, printing inks, UV-curable adhesives, fiber optic coatings, photoresists, photopolymer printing plates, stereolithography resins, composite materials, dental fillings, etc. The recommended dosage is 0.5-4% w / w, based on actual experimental results. It can be completely cured on white or high-titanium dioxide pigmented surfaces. The coating does not yellow, exhibits low post-polymerization effect, and leaves no residue. It can also be used in transparent coatings, and is particularly suitable for products requiring low odor. It also exhibits high initiation efficiency when used alone in styrene-containing unsaturated polyester systems. For acrylic systems, especially colored systems, it is usually necessary to use it in combination with amines or acrylamides, and in combination with other photoinitiators to achieve complete curing of the system. It is particularly suitable for curing low-yellowing, white systems and thick films. Applications include screen printing inks, offset printing inks, flexographic printing inks, and wood coatings. Recommended addition level: 0.5-3.0% (colored systems), 0.3-2.0% (transparent systems).

[0004] On June 14, 2023, ECHA officially included TPO in the 29th batch of the Substances of Very High Concern (SVHC) candidate list. This severely restricted TPO exports, limiting its overseas market. Currently, the main products on the market that can partially replace TPO are TMO and TPO-L, but their overall performance only reaches 50-70% of TPO's. Therefore, finding a phosphoryl initiator that can replace TPO has become particularly urgent.

[0005] The structures of TMO and TPO-L are as follows:

[0006]

[0007] To address the above problems, we have designed a chemical preparation method for TPO derivatives. This invention uses TPO as a raw material, reacting it with paraformaldehyde and aluminum trichloride to generate mono- or dichloromethylated products. Then, under suitable temperature and conditions, these products are reacted with different primary or secondary amines, or directly or partially hydrolyzed, achieving the efficient preparation of a class of TPO derivatives, which can effectively replace TPO. This method is simple to operate, safe, efficient, low-cost, and easy for industrial production. [Summary of the Invention]

[0008] To effectively replace TPO and circumvent the EU ban, this invention designs two types of structures to serve as TPO replacement initiators. These structures are expected to be used as novel phosphoryl photoinitiators. This invention also reports methods for synthesizing these compounds.

[0009] To address the aforementioned problems, this invention reports a photopolymerization reaction for unsaturated systems, comprising a photoinitiator with one or more phosphoryl structures, characterized in that it comprises at least one or any combination of compounds represented by the following general formula, wherein,

[0010] Compounds of general formula I are:

[0011]

[0012] Compounds of general formula II are:

[0013]

[0014] R1 and R2 can be hydroxyl groups, straight-chain or branched monoamino groups containing 1-12 carbon atoms, monoamino groups containing aromatic structures, or cyclic amino structures containing 3-8 carbon atoms. R1 and R2 can be the same or different.

[0015] Compounds of general formula I

[0016]

[0017] R1 can be a hydroxyl group, a straight-chain or branched monoamino group containing 1-12 carbon atoms, a monoamino group containing an aromatic structure, or a cyclic amino structure containing 3-8 carbon atoms.

[0018] The synthesis method is as follows: using photoinitiator TPO as raw material and dichloroethane as solvent, it reacts with an equivalent amount of paraformaldehyde in the presence of aluminum trichloride to generate a monochloromethylated product, which is then reacted with a structure containing a primary or secondary amine or directly hydrolyzed to obtain a compound of general formula I.

[0019]

[0020] Compounds of general formula II

[0021]

[0022] R1 and R2 can be hydroxyl groups, straight-chain or branched monoamino groups containing 1-12 carbon atoms, monoamino groups containing aromatic structures, or cyclic amino structures containing 3-8 carbon atoms. R1 and R2 can be the same or different.

[0023] The synthesis method is as follows: using photoinitiator TPO as raw material and dichloroethane as solvent, it reacts with excess paraformaldehyde in the presence of aluminum trichloride to generate a dichloromethylated product, which is then reacted with excess of a structure containing a primary or secondary amine or directly hydrolyzed to obtain a compound of general formula II.

[0024]

[0025]

[0026] We will explain further in the embodiments. [Attached Image Description]

[0027] The present invention provides the following figures:

[0028] Figure 1 Example 1: Product 1H NMR Spectrum

[0029] Figure 2 Carbon spectrum of the product in Example 1

[0030] Figure 3 Example 2: Product 1H NMR Spectrum

[0031] Figure 4 Example 2: Carbon Spectrum of the Product

[0032] Figure 5 Example 3: Product 1H NMR Spectrum

[0033] Figure 6Example 4: Product 1H NMR Spectrum

[0034] Figure 7 Example 4: Carbon Spectrum of the Product

Detailed Implementation Methods

[0035] The essence of the present invention will be further illustrated below with reference to specific embodiments.

[0036] This invention reports initiators with general formula I-II type TPO derivative structures.

[0037] Compounds of general formula I are:

[0038]

[0039] Compounds of general formula II are:

[0040]

[0041] R1 and R2 can be hydroxyl groups, straight-chain or branched monoamino groups containing 1-12 carbon atoms, monoamino groups containing aromatic structures, or cyclic amino structures containing 3-8 carbon atoms. R1 and R2 can be the same or different.

[0042] Compounds conforming to general formula I include, but are not limited to, the following structures:

[0043]

[0044]

[0045] Compounds conforming to general formula II include, but are not limited to, the following structures:

[0046]

[0047]

[0048]

[0049] Some representative structures of the present invention are further illustrated in the synthetic examples:

[0050] Example 1:

[0051]

[0052] 34.8 g of TPO (0.1 mol, 1.0 eq) was added to 175 g of dichloroethane and stirred until dissolved. Then, 14.7 g of aluminum trichloride (0.11 mol, 1.1 eq) was added all at once, and stirring continued while maintaining the temperature between 25-30 °C. 3.6 g of paraformaldehyde (0.12 mol, 1.2 eq) was added in batches. After the addition was complete, the temperature was maintained at 25-30 °C and stirring continued for 2 hours. Then, the temperature was raised to 40-45 °C and the reaction continued for 3 hours. The reaction was monitored until it ended. After cooling, the reaction solution was quenched in hydrochloric acid solution, and the phases were separated. The organic phase was washed with water, dried, and desolventized to obtain 35.4 g of crude product, with a yield of 89.2%.

[0053] Product chromatogram: 1 H NMR (400MHz, DM SΟ-d6): δ7.90-7.95(m,4H),7.68-7.70(m,2H),7.62-7.65 (m,4H),6.99(s,1H),4.75(s,2H),2.37(s,3H),2.00(s,3H),1.87(s,3H); 13 CNMR (101MHz, DM SΟ-d6): δ140.49,138.17,137.78,134.79,134.40,133.38,133.35,132. 79,131.94,131.86,130.78,130.04,129.71,129.59,129.12,41.17,19.41,19.32,16.63.

[0054] Example 2:

[0055]

[0056] 34.8 g TPO (0.1 mol, 1 eq) was added to 175 g dichloroethane and stirred to dissolve. Then, 40 g aluminum trichloride (0.3 mol, 3 eq) was added all at once, and stirring was continued while maintaining the temperature between 30-35 °C. 10.5 g paraformaldehyde (0.35 mol, 3.5 eq) was added in batches. After the addition was complete, the temperature was maintained at 35-40 °C and stirring was continued for 2 h. Then, the temperature was raised to 45-50 °C and the reaction was continued for 3 h. The reaction was monitored to be basically completed. After cooling, the reaction solution was poured into hydrochloric acid aqueous solution for quenching. The phases were separated, the organic phase was washed with water and dried, and the solvent was removed to obtain 33.8 g of crude product, with a yield of 75.9%. A small amount of monosubstituted product remained.

[0057] Product chromatogram: 1H NMR (400MHz, DM SΟ-d6): δ7.92-7.98(m,4H),7.69-7.73(m,2H),7.62-7.66(m,4H),4.79(s,4H),2.47(s,3H),1.95(s,6H); 13 C NMR (101MHz, DM SΟ-d6): δ140.47,134.48,133.87,133.47,131.94,131.85,129.77,129.65,128.90,41.58,16.84,15.47.

[0058] Example 3:

[0059]

[0060] 8.9 g of the dichloromethylated product (0.02 mol, 1 eq) and 1.75 g of morpholine (0.02 mol, 1 eq) were added to a reaction flask, followed by 10 mL of dichloroethane. The mixture was stirred and heated to 60-70 °C for 5-6 h until the starting material disappeared. The reaction solution was then quenched in water, and the phases were separated. The organic phase was washed with water, dried, and dissolved to obtain 8.8 g of crude product, with a yield of 88.7%.

[0061] Product chromatogram: 1 H NMR (400MHz, DM SΟ-d6): δ7.94-7.99(m,4H),7.74-7.75(m,2H),7.68-7.69(m,4H),4.83 (s,2H),3.54(m,4H),3.48(s,2H),2.49(s,3H),2.37(m,4H),1.99(s,3H),1.98(s,3H).

[0062] Example 4:

[0063]

[0064] 7.9 g of monochloromethylated product (0.02 mol, 1 eq) and 3.2 g of sodium carbonate (0.03 mol, 1.5 eq) were added to a reaction flask, followed by 20 g of water. After the addition was complete, the temperature was gradually increased to 55-65 °C and the reaction was carried out for 8 h. The endpoint was detected by TLC. The reaction system was extracted with ethyl acetate and dried to obtain 5.85 g of crude product, with a yield of 76.2%.

[0065] Product chromatogram: 1H NMR (400MHz, DM SΟ-d6): δ7.92-7.98(m,4H),7.70-7.74(m,2H),7.63-7.63 (m,4H),6.93(s,1H),4.82(s,1H),4.46(s,2H),2.02(s,6H),1.88(s,3H); 13 CNMR (101MHz, DM SΟ-d6): δ170.80,140.05,136.61,134.04,133.25,133.07,131.91,130.30,129.64,129.53,60.22,19.25,16.79,14.54.

[0066] Example 5:

[0067]

[0068] 8.9 g of the dichloromethylated product (0.02 mol, 1 eq) and 17.5 g of morpholine (0.2 mol, 10 eq) were added to a reaction flask, stirred, and heated to 90-100 °C for 8-10 h. The reaction mixture was then observed to have disappeared. The reaction solution was quenched in water, and the phases were separated. The organic phase was washed with water, dried, and solvent-free to obtain 9.2 g of crude product, with a yield of 84.4%.

[0069] Example 6:

[0070]

[0071] 4.96 g of the product from Example 3 (0.01 mol, 1 eq) and 1.6 g of sodium carbonate (0.15 mol, 1.5 eq) were added to a reaction flask, followed by 10 g of water. After the addition was complete, the temperature was gradually increased to 55-65 °C and the reaction was carried out for 8 h. The endpoint was detected by TLC. The reaction system was extracted with ethyl acetate and dried to obtain 3.8 g of crude product, with a yield of 79.5%.

[0072] Example 7:

[0073]

[0074] 7.94 g of monochloromethylated product (0.02 mol, 1 eq), 1.75 g of diethylamine (0.024 mol, 1.2 eq), and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 12 h. The reaction was confirmed to be complete by TLC. The reaction solution was then quenched in water, and the phases were separated. The organic phase was washed with water, dried, and desolventized to obtain 5.28 g of product, with a yield of 60.9%.

[0075] Example 8:

[0076]

[0077] 7.94 g of monochloromethylated product (0.02 mol, 1 eq), 4.4 g of carbazole (0.024 mol, 1.2 eq), and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 15 h. The reaction endpoint was detected by TLC. The reaction solution was quenched in water, and the phases were separated. The organic phase was washed with water, dried, and desolventized to obtain 7.6 g of product, with a yield of 72%.

[0078] Example 9:

[0079]

[0080] 15.9 g of monochloromethylated product (0.04 mol, 2 eq) and 2.16 g of p-phenylenediamine (0.02 mol, 1 eq) and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 20 h. The reaction endpoint was detected by TLC. The reaction solution was quenched in water, and the phases were separated. The organic phase was washed with water, dried, and desolventized to obtain 12.3 g of product, with a yield of 74.2%.

[0081] Example 10:

[0082]

[0083] 7.94 g of monochloromethylated product (0.02 mol, 1 eq) and 5 g of N-methylpiperazine (0.05 mol, 2.5 eq) and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 15 h. The reaction endpoint was detected by TLC. The reaction solution was quenched in water, and the phases were separated. The organic phase was washed with water, dried, and desolventized to obtain 9.8 g of product, with a yield of 85.6%.

[0084] Example 11:

[0085]

[0086] 8.9 g of the dichloromethylated product (0.02 mol, 1 eq) and 4.32 g of p-phenylenediamine (0.04 mol, 2 eq) and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 20 h. The reaction endpoint was detected by TLC. Then, 19.85 g of the monochloromethylated product (0.05 mol, 2.5 eq) was added and the reaction was continued for another 20 h. After the reaction was completed, the reaction solution was quenched in water, the phases were separated, the organic phase was washed with water and dried, and the solvent was removed to obtain 15.5 g of product, with a yield of 59.2%.

[0087] Example 12:

[0088]

[0089] 8.9 g of the dichloromethylated product (0.02 mol, 1 eq) and 3.45 g of piperazine (0.04 mol, 2 eq) and a small amount of catalyst were added to a reaction flask, followed by 30 g of dichloroethane. The mixture was stirred and heated to 70-80 °C for 20 h. The reaction endpoint was detected by TLC. Then, 19.85 g of the monochloromethylated product (0.05 mol, 2.5 eq) was added and the reaction was continued for another 20 h. After the reaction was completed, the reaction solution was quenched in water, the phases were separated, the organic phase was washed with water and dried, and the solvent was removed to obtain 14.2 g of product, with a yield of 56.1%.

[0090] It should be emphasized that the above embodiments are merely exemplary and not limiting. Based on the disclosure of this application, any adjustments or changes to the reaction conditions or parameters that a person skilled in the art might normally adopt will not deviate from the spirit of the invention. The scope of protection of this patent shall be determined by the relevant claims.

Claims

1. This invention reports a photopolymerization reaction for unsaturated systems, comprising one or more phosphoryl-based photoinitiators, characterized in that: It includes at least one or any combination of compounds represented by the following general formulas, wherein, Compounds of general formula I are: Compounds of general formula II are: R1 and R2 can be hydroxyl groups, straight-chain or branched monoamino groups containing 1-12 carbon atoms, monoamino groups containing aromatic structures, or cyclic amino structures containing 3-8 carbon atoms.

2. The following compounds of general formula I R1 can be a hydroxyl group, a straight-chain or branched monoamino group containing 1-12 carbon atoms, a monoamino group containing an aromatic structure, or a cyclic amino structure containing 3-8 carbon atoms. Using photoinitiator TPO as raw material and dichloroethane as solvent, paraformaldehyde is reacted with aluminum trichloride to generate chloromethylated products, which are then reacted with structures containing primary or secondary amines or directly hydrolyzed to obtain compounds of general formula I.

3. The following compounds of general formula II in, R1 and R2 can be hydroxyl groups, straight-chain or branched monoamino groups containing 1-12 carbon atoms, monoamino groups containing aromatic structures, or cyclic amino structures containing 3-8 carbon atoms. R1 and R2 can be the same or different. Using photoinitiator TPO as raw material and dichloroethane as solvent, a dichloromethylated product is generated by reacting with excess paraformaldehyde in the presence of aluminum trichloride. The product is then reacted with excess of a structure containing a primary or secondary amine or directly hydrolyzed to obtain a compound of general formula II.

4. The process described in claims (1) and (2) simultaneously prepares compounds comprising, but not limited to, the following structures:

5. The process described in claims (1) and (3) simultaneously prepares compounds comprising, but not limited to, the following structures:

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