Preparation method of amido ketone bifunctional photoinitiator

Abstract

The invention relates to the technical field of photoinitiators, in particular to a preparation method of an amino ketone bifunctional photoinitiator. According to the technical scheme, the preparation method comprises the following steps: reacting a raw material as shown in a structural formula A with a reagent B under proper reaction conditions Conditions, and then reacting with a compound C to prepare a series of photoinitiator target products with amino ketone bifunctional structural formulas. The target product of the photoinitiator prepared by the invention is the photoinitiator with stronger light absorption capability and higher initiation activity, and is easy to prepare and store, low in cost and more environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of photoinitiators, and in particular to a method for preparing an aminoketone bifunctional photoinitiator. Background Art

[0002] Photoinitiators, also known as photosensitizers or photocuring agents, are compounds that absorb energy of a certain wavelength in the ultraviolet (200-400 nm) or visible (400-800 nm) regions, generating free radicals and cations, thereby initiating polymerization and crosslinking of monomers. α-Aminoketone compounds are currently commonly used as photoinitiators for free radical photopolymerization reactions and are highly active free radical photopolymerization initiators for ethylenically unsaturated compound systems. These compounds have been disclosed in various patents, such as PCT International Publication No. 2008122504A1 and Japanese Patent No. 2009203299A. Commercial photoinitiator products include Irgacure 907 and Irgacure 379.

[0003] However, most photoinitiators have shortcomings in polymerization applications, including carcinogenicity due to cracking or residues, reproductive toxicity caused by benzene / aromatic pollution due to compound migration, VOCs release and unpleasant odors remaining after packaging the finished product, poor solubility resulting in limited scope of use and dosage, and environmental unfriendliness. These shortcomings have become issues of increasing concern in the field of radiation curing, and at the same time have promoted the continuous research and development of new environmentally friendly photoinitiators. Therefore, from the perspective of industrial application scenarios, environmental protection of manufacturing processes and environmental protection of people's livelihood applications, the research and development of new photoinitiators should not only be committed to solving the above-mentioned challenging problems and providing new green, environmentally friendly and non-toxic compounds, but also require these new compounds to have economic cost competitiveness and comprehensive performance competitiveness as much as possible.

[0004] Shenzhen Xinyan Material Technology Co., Ltd. applied for patent CN115010614A, disclosing a series of α-aminoketone bifunctional compounds with photoinitiator activity. However, the process involved is highly dangerous and requires the use of an excessive chlorine source. From the perspective of environmental protection and convenience, it is not suitable for industrial production, and the activity of the target compounds generated needs to be further improved. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the present invention provides a method for preparing an aminoketone bifunctional photoinitiator, which solves the problems raised in the background art.

[0006] The present invention solves the above-mentioned technical problems in the following ways:

[0007] An aminoketone bifunctional photoinitiator having the structure of the following formula (I):

[0008]

[0009] In the above structural formula (I), R is represented by wherein R1 and R2 are independently selected from C1-C 10 Straight or branched alkyl, C4-C 10 or R1 and R2 may be connected to each other or through -O-, -S-, -N- to form a five-membered ring or a six-membered cyclic group.

[0010] A method for preparing an aminoketone bifunctional photoinitiator comprises preparing a target product from corresponding raw materials A, B, and C under appropriate reaction conditions. The reaction formula is as follows:

[0011]

[0012] In the above reaction formula, the definitions of each group and substance are the same as those of the corresponding items in claim 1. Conditions refers to any one of organic base, inorganic base, catalyst or promoter, inhibitor, heat, microwave, ultrasound, vacuum or pressure, solvent, etc., or a combination of any two or more of the above factors; wherein the catalyst or promoter refers to a Lewis acidic or basic compound, and X in compound C = Cl, Br or I; specifically comprising the following steps:

[0013] S1, using the acyl donor of the raw material diphenylmethane A and 2-chloropropionyl chloride B to carry out Friedel-Arafts acylation reaction under the action of Lewis acid to obtain the corresponding intermediate a acylated product aromatic ketone;

[0014]

[0015] S2, intermediate a undergoes substitution reaction with raw material RH to obtain intermediate c;

[0016]

[0017] Among the raw materials RH, R is:

[0018] S3, intermediate c undergoes Stevens rearrangement reaction with raw material C under alkaline conditions to generate product D, which is a bifunctional compound of the general structural formula α-amino ketone;

[0019]

[0020] Wherein X in the raw material C is chlorine or bromine.

[0021] On the basis of the above technical solution, the present invention can also be improved as follows.

[0022] Furthermore, in S1, diphenylmethane is dissolved in dichloroethane, a catalyst Lewis acid is added at 0°C, 2-chloropropionyl chloride is added dropwise at 0-5°C, and after the addition is completed, the mixture is kept at the same temperature for 3-6 hours.

[0023] Furthermore, the Lewis acid in S1 is selected from aluminum trichloride, ferric chloride, zinc chloride, and titanium tetrachloride, and the addition amount is in the range of 0.05-2.5 equivalents, preferably in the range of 1.0-1.2 equivalents; the addition amount of the raw material 2-chloropropionyl chloride is in the range of 1.0-3.0 equivalents, preferably in the range of 1.0-1.4 equivalents; after the dropwise addition is completed, the insulation time is 2-6 hours, preferably 3-3.5 hours.

[0024] Furthermore, the catalyst used in S2 is a basic catalyst.

[0025] Furthermore, RH in S2 is preferably a secondary amine, more preferably dimethylamine, diethylamine, morpholine, or piperidine.

[0026] Furthermore, in S3, the quaternary ammonium salt compound is dissolved in a 30%-40wt% sodium hydroxide solution or a strong alkaline solution such as potassium hydroxide, and rearrangement reaction is carried out at 60-100°C for 3-6 hours, more preferably at 70-90°C for 3-4 hours.

[0027] Furthermore, the base in S3 is selected from one or more of potassium carbonate, potassium hydroxide, and sodium hydroxide, and the ratio of the base to the compound is 1:(3-10), exemplified by 1:4, 1:5, 1:6, 1:7 or 1:8, but not limited thereto.

[0028] Furthermore, after the rearrangement reaction is completed, the step of purifying the obtained product is further included, specifically, the reaction mixture is cooled to room temperature, dichloromethane is added for extraction, the organic phase is washed with water twice, dried over anhydrous sodium sulfate, and concentrated to obtain product D.

[0029] A hybrid system curable by ultraviolet radiation comprises at least one polymerizable ethylenically unsaturated photopolymerizable compound and an α-aminoketone difunctional compound having the general structural formula (I). The α-aminoketone difunctional compound includes but is not limited to the following exemplary structures:

[0030]

[0031] In the above reaction formula, the definitions of each group and Conditions are the same as those of the corresponding items in claim (1).

[0032] The present invention provides a method for preparing an aminoketone bifunctional photoinitiator. It has the following beneficial effects:

[0033] In the preparation method of the α-amino ketone bifunctional compound of the present invention, diphenylmethane and 2-chloropropionyl chloride are used as raw materials, which reduces the cost of raw materials and is more environmentally friendly. In addition, the preparation method of the present invention has a high yield of more than 85% and a purity of more than 95%.

[0034] Compared with existing products, this type of product uses diphenylmethane as the key group and is prepared through easy-to-operate process flow such as Friedel-Crafts reaction, substitution, and rearrangement to improve photoinitiation efficiency and activity;

[0035] At the same time, this compound is an environmentally friendly, non-toxic and highly efficient photoinitiator, which avoids the release of volatile toxic small molecule organic compounds during the photocuring process, or the generation of irritating and unpleasant odors, or physiological toxicity caused by compound migration. It has a good promoting effect on the promotion and application of ultraviolet radiation photocuring.

[0036] Exemplary but non-limiting examples of α-aminoketone bifunctional compounds that can be prepared using the technology disclosed in this application include the following structures:

[0037] DETAILED DESCRIPTION

[0038] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0039] The present invention provides the following embodiments:

[0040] Example 1

[0041]

[0042] Under argon protection, 168 g of diphenylmethane was added to 504 g of dichloroethane, the temperature was lowered to 0°C, 292 g of anhydrous aluminum chloride was slowly added, and after stirring for 20 min, 254 g of 2-chloropropionyl chloride was slowly added dropwise at 0-5°C. After the addition was completed, the mixture was kept at this temperature for 3 h, quenched by adding 3% dilute hydrochloric acid, the organic layer was separated, washed with water until neutral, dried, and concentrated to obtain the acylated intermediate;

[0043] Then, the above-mentioned chlorinated intermediate was placed in a 2500 ml flask, and a catalyst and 1000 g of dichloroethane were added. After stirring and cooling to 5-10 ° C, dimethylamine gas was introduced and then heated to 35 ° C for 8 hours. The organic phase was desolvated and recrystallized from ethanol to obtain the ammonia-substituted intermediate.

[0044] Finally, the above amino intermediate was put into a reaction flask, 1000 g of toluene was added, 254 g of benzyl chloride was slowly added dropwise, the temperature was raised to 90°C and reacted for 10 hours, then liquid alkali was added and refluxed for 3 hours. After cooling, the organic phase was separated, the aqueous phase was extracted with dichloromethane, and the organic phases were combined, extracted, and dried to obtain a crude product, which was recrystallized from ethanol to obtain 461 g of the target product with a total yield of 84.6%.

[0045] Example 2

[0046]

[0047] Under argon protection, 84 g of diphenylmethane was added to 252 g of dichloromethane, the temperature was lowered to 0°C, 147 g of anhydrous aluminum chloride was slowly added, and after stirring for 30 min, 127 g of 2-chloropropionyl chloride was slowly added dropwise at the same temperature. After the addition was completed, the temperature was kept for 3 h. After the reaction of the raw materials was complete by TLC, ice water was added to quench, the organic layer was separated, washed until neutral, dried, and concentrated to obtain the Friedel-Crafts acylated intermediate;

[0048] Then the above chlorinated intermediate was put into a flask, and a catalyst and 1000 g of dichloroethane were added. After stirring evenly, 73 g of diethylamine was added and the temperature was raised to 50°C for 8 h. The organic phase was desolvated and recrystallized with methanol to obtain the ammonia-substituted intermediate.

[0049] Finally, the above-mentioned amino intermediate was placed in a reaction flask, 1000 g of toluene was added, and 171 g of benzyl bromide was slowly added dropwise. The temperature was raised to 90°C and reacted for 10 h. After that, liquid caustic soda was added and refluxed for 2 h. After cooling, the organic phase was separated, extracted, and dried to obtain a crude product. After recrystallization from ethanol, 244 g of the target product was obtained, with a total yield of 81%.

[0050] Example 3

[0051]

[0052] Under nitrogen protection, 84 g of diphenylmethane was added to 252 g of dichloroethane, the temperature was lowered to 0°C, 147 g of anhydrous aluminum chloride was slowly added, and after stirring for 30 min, 127 g of 2-chloropropionyl chloride was slowly added dropwise at the same temperature. After the addition was complete, the temperature was kept for 3 h. After TLC, 3% dilute hydrochloric acid was added to quench the reaction after the raw materials reacted completely. The organic layer was separated, washed until neutral, dried, and concentrated to obtain the Friedel-Crafts acylated intermediate.

[0053] Then the above chlorinated intermediate was put into a flask, and a catalyst and 1000 g of dichloroethane were added. After stirring evenly, 130.5 g of morpholine was added and the temperature was raised to 50°C for reaction for 8 h. The organic phase was desolvated and recrystallized with ethanol to precipitate the ammonia-substituted intermediate at 0°C.

[0054] Finally, the above-mentioned amino intermediate was put into a reaction flask, 1000 g of chlorobenzene was added, and 171 g of benzyl bromide was slowly added dropwise. The temperature was raised to 90°C and reacted for 10 hours. Liquid alkali was added and refluxed for 2 hours. After cooling, the organic phase was separated, extracted, and dried to obtain a crude product. After recrystallization from ethanol, 281 g of the target product was obtained, with a total yield of 89% and a GC purity of 97.9%.

[0055] Example 4

[0056]

[0057] Under nitrogen protection, 168 g of diphenylmethane was added to 500 g of dichloroethane, the temperature was lowered to 0°C, 294 g of anhydrous aluminum chloride was slowly added, and after stirring for 30 min, 254 g of 2-chloropropionyl chloride was slowly added dropwise at the same temperature. After the addition was complete, the mixture was kept warm for 3 h. After TLC, ice water was added to quench the reaction after the raw materials reacted completely. The organic layer was separated, washed until neutral, dried, and concentrated to obtain the Friedel-Crafts acylated intermediate.

[0058] Then the above chlorinated intermediate was put into a flask, and a catalyst and 1050 g of dichloroethane were added. After stirring evenly, 170 g of piperidine was added, and the temperature was raised to 50°C for reaction for 8 h. The organic phase was desolvated and recrystallized with methanol to obtain the ammonia-substituted intermediate.

[0059] Finally, the above-mentioned amino intermediate was put into a reaction flask, 1000 g of toluene was added, 250 g of benzyl bromide was slowly added dropwise, the temperature was raised to 90°C and reacted for 10 hours, then liquid alkali was added and refluxed for 2 hours. After cooling, the organic phase was separated, extracted, and dried to obtain a crude product. After recrystallization with ethanol, the target product was precipitated at 0°C, filtered, and dried to obtain 541 g, with a total yield of 86.4% and a GC purity of 98.12%.

[0060] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as illustrative and non-restrictive in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and all changes that come within the meaning and range of equivalents of the claims are intended to be included therein.

[0061] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An aminoketone bifunctional photoinitiator, characterized in that: It has the structure of the following formula (I): In the above structural formula (I), R is represented by wherein R1 and R2 are independently selected from C1-C 10 Straight or branched alkyl, C4-C 10 or R1 and R2 may be connected to each other or through -O-, -S-, -N- to form a five-membered ring or a six-membered cyclic group.

2. A method for preparing the aminoketone bifunctional photoinitiator according to claim 1, characterized in that: The target product is prepared by the corresponding raw materials A, B and C under appropriate reaction conditions. The reaction formula is as follows: In the above reaction formula, the definitions of each group and substance are the same as those of the corresponding items in claim 1. Conditions refers to any one of organic base, inorganic base, catalyst or promoter, inhibitor, heat, microwave, ultrasound, vacuum or pressure, solvent, etc., or a combination of any two or more of the above factors; wherein the catalyst or promoter refers to a Lewis acidic or basic compound, and X in compound C = Cl, Br or I; specifically comprising the following steps: S1. Compounds A and B undergo Friedel-Crafts acylation reaction catalyzed by Lewis acid to obtain the corresponding intermediate a; S2, intermediate a then undergoes aminolysis reaction with RH to generate intermediate c; S3, intermediate c then reacts with benzyl halide C to form a quaternary ammonium salt of α-amino ketone, which undergoes Steves rearrangement reaction under alkaline conditions to produce product D; 3. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: In S1, diphenylmethane is dissolved in dichloroethane, a catalyst Lewis acid is added at 0°C, 2-chloropropionyl chloride is added dropwise at 0-5°C, and after the addition is complete, the mixture is kept at the same temperature for 3-6 hours.

4. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: The Lewis acid in S1 is selected from aluminum trichloride, ferric chloride, zinc chloride, and titanium tetrachloride, and the addition amount is in the range of 0.05-2.5 equivalents, preferably in the range of 1.0-1.2 equivalents; the addition amount of the raw material 2-chloropropionyl chloride is in the range of 1.0-3.0 equivalents, preferably in the range of 1.0-1.4 equivalents; after the dropwise addition is completed, the insulation time is 2-6 hours, preferably 3-3.5 hours.

5. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: The catalyst used in S2 is a basic catalyst.

6. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: Preferred RH in S2 is a secondary amine, more preferably dimethylamine, diethylamine, morpholine, or piperidine.

7. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: In S3, the quaternary ammonium salt compound is dissolved in a 30%-40wt% sodium hydroxide solution or a strong alkaline solution such as potassium hydroxide, and rearrangement reaction is carried out at 60-100°C for 3-6 hours.

8. The method for preparing an aminoketone bifunctional photoinitiator according to claim 2, wherein: The base in S3 is selected from one or more of potassium carbonate, potassium hydroxide, and sodium hydroxide, and the ratio of the base to the compound is 1:(3-10), and exemplarily 1:4, 1:5, 1:6, 1:7 or 1:

8.

9. The method for preparing an aminoketone bifunctional photoinitiator according to claim 7, characterized in that: After the rearrangement reaction is completed, the step of purifying the obtained product is further included, specifically, the reaction temperature is cooled to room temperature, dichloromethane is added for extraction, the organic phase is washed with water twice, dried over anhydrous sodium sulfate, and concentrated to obtain product D.

10. A hybrid system curable by ultraviolet radiation, characterized in that Containing at least one polymerizable ethylenically unsaturated photopolymerizable compound and an α-amino ketone bifunctional compound according to the general structural formula (I) as claimed in claim 1, the α-amino ketone bifunctional compound includes but is not limited to the following exemplary structures: In the above reaction formula, the definitions of each group and Conditions are the same as those of the corresponding items in claim (1).

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