Synthetic method of photoinitiator 389

Abstract

The invention relates to the field of chemical synthesis, in particular to a synthesis method for preparing a photoinitiator 389, and belongs to the technical field of organic chemistry. The synthesis method comprises the following steps: (1) preparing a corresponding piperidine substituted ketone compound III from a compound I and piperidine; (2) carrying out bromination reaction on the compound III to obtain an alpha carbonyl brominated compound IV; (3) aminating the compound IV to obtain an alpha-carbonyl dimethylamine compound V; (4) carrying out benzylation on the compound V to obtain a corresponding photoinitiator 389 VI; the invention provides the synthesis method of the photoinitiator 389, the reaction post-treatment is simple, the purity of a target key intermediate can reach 95% without column purification and liquid phase preparation, and a reliable synthesis method is provided for subsequent research and use based on the photoinitiator 389.

Description

Technical Field

[0001] The present invention relates to the field of chemical synthesis, and specifically to a method for synthesizing photoinitiator 389. Background Art

[0002] Photoinitiators, also known as UV-curing photoinitiators, are a class of compounds that can absorb energy of a certain wavelength in the ultraviolet region (250 - 420 nm) or visible region (400 - 800 nm), generating free radicals, cations, etc., thereby initiating the polymerization and crosslinking curing of monomers. 389 belongs to the cleavage type initiator. It absorbs ultraviolet quanta emitted by strong ultraviolet lamps, thereby initiating polymerization crosslinking and grafting reactions, enabling a liquid to form a solid film within a fraction of a second. Currently, there are mature industrial production processes. However, in order to reduce costs to a greater extent, partial structural and process optimizations are carried out to reduce costs, replacing the fluorine element in the raw materials with chlorine - chlorobenzene is used as the raw material instead of fluorobenzene. This invention patent reports on the research of the synthesis method of photoinitiator 389.

[0003] Regarding the reported routes for synthesizing 389, Patent EP284561 reports the following synthesis method route for this product. This synthesis route uses fluorobenzene as the starting material. This route has short linear synthesis steps and high overall yields. However, the cost of the key raw materials has gradually increased, resulting in limitations in large-scale industrial production. Therefore, it is particularly important to develop a route that is more conducive to industrial production.

[0004]

[0005] In summary, the reaction conditions in the existing literature reports do not have a synthesis method for producing 389 with lower costs in large-scale industrial production. Based on this, the inventor of the present invention provides a synthesis method using chlorobenzene as the starting material. This method is simple and efficient, and can obtain a target precursor product with a purity of 95% without additional liquid phase separation preparation or expensive catalysts, thereby meeting various requirements for significantly reducing costs. Summary of the Invention

[0006] The main purpose of the present invention is to provide a method for synthesizing photoinitiator 389. This synthesis method is easy to operate, has short synthesis steps, high product yields, and simple purification. It does not require column purification and liquid phase separation preparation, and can achieve a product with a purity of over 95% through simple column purification and crystallization operations.

[0007] The technical solution adopted by the present invention is specifically as follows:

[0008] A method for synthesizing photoinitiator 389, the structural formula of photoinitiator 389 is as shown in Formula VII

[0009]

[0010] The method for synthesizing the compound shown in Formula VII includes:

[0011] Dissolve Compound I in 1# organic solvent, add it to the corresponding reagent of acyl chloride, and add an aluminum reagent and stir for reaction. After the reaction is completed, post-treatment is carried out to obtain a crude product, and after treatment, Compound II is obtained;

[0012] Among them, the structural formulas of the said Compound I and II are respectively:

[0013]

[0014] Dissolve Compound II in 2# organic solvent, add piperidine reagent for C-N coupling to obtain Compound III;

[0015] Among them, the structural formula of the said Compound III is:

[0016]

[0017] Dissolve Compound III in 3# organic solvent, add an acid reagent to prepare hydrochloride Compound IV;

[0018] Among them, the structural formula of the said Compound IV is:

[0019]

[0020] Dissolve Compound IV in 4# organic solvent, add a brominating reagent for bromination to obtain Compound V;

[0021] Among them, the structural formula of the said Compound V is:

[0022]

[0023] Dissolve Compound V in 5# organic solvent, add a base and dimethylamine solution for reaction, and after the reaction, Compound VI is obtained;

[0024] Among them, the structural formula of the said Compound VI is:

[0025]

[0026] Dissolve Compound VI in 6# organic solvent, add a base and benzyl chloride for reaction to obtain Compound VII.

[0027] Preferably, the acyl chloride is one of A-butyryl chloride, butyryl chloride or 4-iodobutyryl chloride;

[0028] The used 1# organic solvent is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane or n-heptane.

[0029] Preferably, the 2# organic solvent is one of ethanol, methanol, water, dioxane or dichloroethane.

[0030] Preferably, the acid reagent is one of hydrochloric acid, sulfuric acid, hydrobromic acid or phosphoric acid;

[0031] The 3# organic solvent is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane, n-heptane or dioxane.

[0032] Preferably, the bromination reagent is one of copper bromide, bromine or a hydrobromic acid plus hydrogen peroxide system;

[0033] The 4# organic solvent used is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane or n-heptane.

[0034] Preferably, the dimethylamine solution is one of liquid dimethylamine, aqueous dimethylamine solution, dimethylamine methanol solution, dimethylamine ethanol solution or dimethylamine tetrahydrofuran solution;

[0035] The 5# organic solvent is one of dichloromethane, dichloroethane, methanol, ethanol, dioxane and water, tetrahydrofuran and water, methanol and water or ethanol and water.

[0036] Preferably, the base is one of triethylamine, pyrrolidine, diethylamine, dimethylamine, potassium hydroxide, lithium hydroxide, sodium hydroxide, sodium formate, sodium acetate or ammonia water;

[0037] The 6# organic solvent is one of dichloromethane, dichloroethane, methanol, ethanol, dioxane and water, tetrahydrofuran and water, methanol and water or ethanol and water.

[0038] The beneficial effects of the present invention are as follows: The present invention provides a synthesis method of photoinitiator 389. This method is simple, efficient, and the product is easy to purify. A product purity of 95% can be obtained without column purification or liquid-phase preparation. At the same time, since most of the reaction conditions are relatively mild, it is suitable for industrial scale production. Because there is no literature reporting the synthesis route of photoinitiator 389 involved in the present invention, the present invention is the first to propose using cheaper starting materials to synthesize 389 and adopting the strategy of using chlorobenzene as the raw material, making this process have the possibility of large-scale industrial production. Description of the Drawings

[0039] Figure 1 is the synthesis route diagram of the present invention;

[0040] Figure 2 is the 1 1H-NMR spectrum and mass spectrum of the product in the product implementation case of the present invention. Detailed Embodiments

[0041] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. And all experimental methods used in the following embodiments are conventional methods unless otherwise specified.

[0042] Example 1

[0043] This embodiment provides a synthesis method of 389. The synthesis route is as Figure 1 shown, and specifically includes the following steps:

[0044] (1) Preparation of Compound II

[0045] Add Compound I (56.3 g, 500 mmol) dissolved in 300 mL of dichloroethane to a 1 L three-necked flask, then add aluminum chloride. Dropwise add butyryl chloride at 0 °C, and warm up to 35 °C and react overnight. After the reaction is complete, quench with dilute hydrochloric acid, then wash with alkali and water. The organic phase is dried and concentrated to obtain 88.7 g of crude Compound II, with a yield of 95.0%.

[0046] (2) Preparation of Compound III

[0047] Add Compound II (56.3 g, 300 mmol), piperidine (120 g, 1.5 mol), and deionized water (54 g, 3.0 mol) to a 1 L high-temperature and high-pressure autoclave, stir and warm up to 200 °C and react overnight. After the reaction is complete, add water and benzene, adsorb with activated carbon, crystals precipitate from the organic phase, dry and concentrate to obtain Compound III (63 g), with a crude yield of 91%.

[0048] (3) Preparation of Compound IV

[0049] Dissolve Compound III (92.5 g, 400 mmol) in 450 mL of tetrahydrofuran in a 500 mL single-necked flask, add hydrochloric acid aqueous solution (38 mL, 450 mmol), stir for 1 hour, solids precipitate in the reaction flask, filter and dry to obtain Compound IV (105 g), with a crude yield of 98%.

[0050] (4) Preparation of Compound V

[0051] Add compound Ⅳ (8.5 g, 32 mmol) into a 250 mL single-necked flask, dissolve it in 100 mL of dichloroethane, add aqueous hydrobromic acid solution (8 g, 39 mmol), stir for 5 minutes, then slowly add bromine (4.1 g, 26 mmol). After the addition is complete, stir and heat up to 100 °C for reaction for 8 h. After the reaction is complete, quench with aqueous sodium bicarbonate solution, wash with water multiple times, dry and concentrate to obtain compound Ⅴ (11.3 g), with a crude yield of 102%.

[0052] (5) Preparation of compound Ⅵ

[0053] Dissolve compound Ⅴ (12.4 g, 40 mmol) in 150 mL of dichloroethane in a 500 mL single-necked flask. After cooling to 0 °C, add sodium hydroxide (2.1 g, 52 mmol), stir, and then slowly add aqueous dimethylamine solution (18 g, 160 mmol) and heat up to 65 °C for reaction overnight. After the reaction is complete, slowly add water to quench the reaction while cooling. Wash the organic phase with water to obtain compound Ⅴ (12.1 g), with a yield of 110%.

[0054] (6) Preparation of compound Ⅶ

[0055] Dissolve compound Ⅴ (8.2 g, 30 mmol) in 100 mL of dichloroethane in a 500 mL single-necked flask. Add potassium iodide (0.3 g, 1.8 mmol), benzyl chloride (5 g, 40 mmol), and water (0.2 g, 11 mmol). Heat up to 70 °C and stir for reaction for 10 h. After returning to room temperature, slowly add aqueous sodium hydroxide solution (15 g, 150 mmol), heat up to 75 °C and stir for reaction overnight. After monitoring until the reaction is complete, wash and concentrate the organic phase, and directly filter through simple column chromatography (PE:EA = 10:1), and recrystallize with methanol to obtain compound Ⅶ (7.6 g), with a yield of 70.1%.

[0056] In this example, compound Ⅰ is used as the raw material, and the target compound Ⅶ is obtained through 5-step reactions. In addition, the conversion structure of the series of compounds in this example is Figure 1 as shown, and the product 1 The 1H-NMR spectrum and mass spectrum are as Figure 2 shown.

[0057] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included in the present invention.

[0058] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only an independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for synthesizing a photoinitiator 389, wherein the photoinitiator 389 has a structural formula as shown in Formula VII It is characterized in that The method for synthesizing the compound shown in formula VII comprises: Dissolve compound I in 1# organic solvent, add to the reagent corresponding to the acyl chloride, add aluminum reagent and stir to react, after the reaction is completed, treat to obtain a crude product, and then treat to obtain compound II; Wherein, the structural formulas of the compounds Ⅰ and Ⅱ are respectively: Dissolve compound II in 2# organic solvent, add piperidine reagent CN for coupling to obtain compound III; Wherein, the structural formula of the compound III is: Dissolve compound III in 3# organic solvent, add acid reagent to prepare hydrochloride compound IV; Wherein, the structural formula of the compound IV is: Dissolve compound IV in 4# organic solvent, add bromination reagent to obtain compound V; Wherein, the structural formula of the compound V is: Dissolve compound V in 5# organic solvent, add alkali and dimethylamine solution to react, and obtain compound VI after the reaction; Wherein, the structural formula of the compound VI is: Dissolve compound VI in 6# organic solvent, add base and benzyl chloride to react and obtain compound VII.

2. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The acyl chloride is one of A-butyryl chloride, butyryl chloride or 4-iodobutyryl chloride; The 1# organic solvent used is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane or n-heptane.

3. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The 2# organic solvent is one of ethanol, methanol, water, dioxane or ethylene dichloride.

4. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The acid reagent is one of hydrochloric acid, sulfuric acid, hydrobromic acid or phosphoric acid; The 3# organic solvent is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane, n-heptane or dioxane.

5. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The bromination reagent is one of copper bromide, bromine or hydrobromic acid plus hydrogen peroxide system; The 4# organic solvent used is one of dichloromethane, dichloroethane, tetrahydrofuran, ethanol, methanol, n-hexane or n-heptane.

6. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The dimethylamine solution is one of dimethylamine liquid, dimethylamine aqueous solution, dimethylamine methanol solution, dimethylamine ethanol solution or dimethylamine tetrahydrofuran solution; The 5# organic solvent is one of dichloromethane, dichloroethane, methanol, ethanol, dioxane and water, tetrahydrofuran and water, methanol and water, or ethanol and water.

7. The method for synthesizing a photoinitiator according to claim 1, characterized in that: The base is one of triethylamine, tetrahydropyrrole, diethylamine, dimethylamine, potassium hydroxide, lithium hydroxide, sodium hydroxide, sodium formate, sodium acetate or ammonia; The 6# organic solvent is one of dichloromethane, dichloroethane, methanol, ethanol, dioxane and water, tetrahydrofuran and water, methanol and water, or ethanol and water.

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