Preparation method of blue light absorbing material

Abstract

According to the preparation method of the blue light absorbing material, potassium carbonate or sodium carbonate is used for catalyzing etherification reaction, reaction heat release is reduced, meanwhile, the problems of easy gelatinization, easy material rushing and the like caused by reaction overheating are avoided, potassium tert-butoxide is used for catalyzing condensation reaction, the purification procedure is simplified, the reaction conversion rate is increased, and the yield of the blue light absorbing material is increased. Meanwhile, impurity removal methods such as quenching acidification and recrystallization are matched, so that pilot-scale preparation of the beta-diketone compound is realized, and the purity and yield of the product are improved. The blue light absorptivity of the final product is more than 80% under the concentration of 3mg / ml, and the market-oriented and large-scale production requirements are met. The preparation process disclosed by the invention is wide in raw material source, simple in process and high in practical operability, and has a relatively great application prospect in development and production of blue light absorbing materials.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a method for preparing a blue light absorbing material. Background Art

[0002] LED light sources have the advantages of small size, long life, and high efficiency. They have gradually become the mainstream products in the field of lighting and colorimetry. They are widely used in common electronic products such as mobile phones, tablets, and computers. LED light sources have penetrated into our daily lives. Blue light is an important component of LED light sources, but the wavelength of blue light is longer than that of ultraviolet light, and the energy is lower than that of ultraviolet light. It will cause irreversible damage to vision, especially for people in the growth and development period. If they are exposed to LED light sources for a long time, the degree of eye damage will be greater, and even blinding eye diseases will be induced. Therefore, the development of blue light absorbers is of great significance to protecting vision.

[0003] β-diketone compounds are compounds containing a 1,3-dicarbonyl structure. The special keto-enol isomerism gives them special coordination and photochemical properties, and they can be used as ligands for metal ion chelation. Chelating β-diketone compounds with rare earth ions can effectively improve the light absorption capacity of rare earth ions. Therefore, β-diketone compounds are used in the development of blue light absorbing materials.

[0004] CN108191624A discloses a UV-blue light absorbing material. During the preparation process, the final product β-diketone compound output rate is 50%-69%, which reflects that the existing preparation process of blue light absorbing materials based on β-diketone compounds has low reaction conversion rate, low product purity, low yield, serious pollution in the reaction process, etc., which affects the development of pilot process and is difficult to achieve mass production. Therefore, optimizing the preparation method of β-diketone compounds is of great significance to the research and development of blue light absorbing products and to help protect vision. Summary of the invention

[0005] In view of the above problems, the present invention provides a method for preparing a blue light absorbing material. By optimizing the selection of catalysts for etherification reaction and condensation reaction, the pilot-scale preparation of β-diketone compounds is achieved, while the reaction conversion rate and product purity are improved. This method has a wide source of raw materials, a streamlined process, and strong practicability, and has great application prospects in the development and production of blue light absorbing materials.

[0006] A method for preparing a blue light absorbing material, characterized in that it comprises the following steps:

[0007] Dissolve p-hydroxyacetophenone and alkyl halide in a solvent, stir, add a catalyst, and keep the temperature at 88-90°C for 4.5-5 hours to obtain alkoxyacetophenone. The hydroxyl group and alkyl halide undergo etherification reaction to obtain alkoxy group. The reaction activity of both is low, so a catalyst and high temperature (88-90°C) are required to promote the reaction. The reaction can be completed in about 5 hours.

[0008] Dissolve methyl phenylformate and potassium tert-butoxide in a solvent, add alkoxyacetophenone while stirring, and react for 1-2 hours to obtain a reaction system. This step is a condensation reaction;

[0009] The reaction system is poured into water for quenching, and 1-phenyl-3-alkoxyphenyl-1,3-propanedione compounds, i.e., blue light absorbing materials, are obtained through acidification, washing, filtering and recrystallization.

[0010] Preferably, the catalyst is sodium carbonate or potassium carbonate. The catalyst of the etherification reaction will affect the conversion rate of the reaction. The catalyst is generally an alkaline substance. The process of adding the catalyst will release a lot of heat, leading to gelatinization and an increase in by-products. Selecting potassium carbonate or sodium carbonate as a catalyst can not only meet the conditions of alkaline catalysis, but also avoid violent heat release of the reaction, while improving the conversion rate of the reaction.

[0011] Preferably, the temperature is controlled below 75°C when the catalyst is added. The catalyst is generally an alkaline substance. The process of adding the catalyst will release a lot of heat, leading to gelatinization and an increase in by-products. Therefore, the process of adding the catalyst requires controlling the reaction temperature to slowly release heat and promote the reaction.

[0012] Preferably, the alkyl halide includes one of propyl bromide, butyl bromide, pentane bromide, hexyl bromide and benzyl bromide.

[0013] Preferably, the solvent is N,N-dimethylformamide.

[0014] Preferably, the molar ratio of p-hydroxyacetophenone, alkyl halide and catalyst is 1:1-1.2:1-1.5.

[0015] Preferably, during the process of maintaining the reaction at 88-90° C. for 4.5-5 hours, the reaction progress is monitored by thin layer chromatography (TLC) every hour. When the reaction is completely completed, the catalyst is removed by suction filtration, and the alkyl halide and the solvent are removed by rotary evaporation to obtain alkoxyacetophenone with higher purity.

[0016] Preferably, the molar ratio of methyl benzoate, tert-butyl alcohol and alkoxyacetophenone is 1:1-1.5:2.25-2.5. Tert-butyl alcohol, as an alkaline condensing agent for the condensation reaction, significantly improves the yield of 1-phenyl-3-alkoxyphenyl-1,3-propanedione compounds and can be removed after subsequent acidification without affecting the purity of the product.

[0017] Preferably, during the reaction for 1 hour, the reaction progress is monitored every 15 minutes using a thin layer plate (TLC). When the reaction is completely completed, the reaction system is poured into cold water for quenching. The quenching cools the reaction system to provide a good reaction environment for acidification and impurity removal.

[0018] Preferably, the acidification is to add concentrated hydrochloric acid to the quenched reaction system until the pH of the system is 5-6, control the degree of acidification to avoid affecting the purity of subsequent products, filter and obtain a filter cake. Acidification in the quenching system can completely neutralize all catalysts involved in the reaction, while avoiding white smoke generated by acidification from polluting the environment and endangering operators.

[0019] Preferably, the washing is to wash the filter cake obtained by acidification with water, make the pH of the filtrate to 6-8, make the filter cake neutral, fully remove the hydrochloric acid, and at the same time, add methanol to disperse the filter cake, filter and obtain a solid product.

[0020] Preferably, the recrystallization is to dissolve the solid product obtained by washing with methanol, heat the solution, cool and reflux, and repeat this step until the methanol obtained by reflux is clear to obtain 1-phenyl-3-alkoxyphenyl-1,3-propanedione compounds, that is, blue light absorbing materials. Recrystallization can further remove impurities contained in the product and improve the purity of the product. In addition, a large amount of methanol consumed in the recrystallization can be collected in the reflux liquid, which is acidified and washed again before recrystallization, thereby increasing the yield while reducing waste.

[0021] Preferably, the blue light absorbing material has the structural formula of Formula 1

[0022] Formula 1:

[0023] Among them, R 1 Including propyl, butyl, pentyl, hexyl, benzyl, R 2 A kind of phenyl group and benzyl group, the structural formula conforms to the characteristics of β-diketone compounds.

[0024] Compared with the prior art, the beneficial effect of this solution is that by optimizing the selection of catalysts in the preparation of β-diketone compounds, the reaction conversion rate and product purity are significantly improved, which is specifically reflected in:

[0025] First, in the etherification reaction, the hydroxyl group of the p-hydroxyacetophenone used in this scheme is a strongly acidic hydroxyl group. If a conventional strong base catalyst is still used, such as sodium hydroxide, the sodium hydroxide will react with the hydroxyl group to release heat, and will also react with the alkyl halide to release heat for a second time, resulting in overheating of the reaction and gelatinization of the product. The accumulated heat of the reaction will lead to material impact and even explosion risk. However, the use of potassium carbonate and sodium carbonate with relatively weak alkalinity as catalysts avoids the reaction of the catalyst with the alkyl halide, reduces heat release, and the maximum reaction temperature is lower than 95°C, avoiding the impact of severe heat release.

[0026] Second, in the condensation reaction, the commonly used sodium methoxide or sodium ethoxide not only consumes a large amount of alcohol in the preparation process, but also needs to be continuously distilled to remove the produced alcohol after the reaction to ensure that the reaction continues. During the distillation process, part of the product will be distilled out to reduce the yield, and the content of by-products in the conversion product is relatively high, which has a greater impact on the subsequent impurity removal. This scheme uses potassium tert-butoxide as an alkaline condensation agent, which is much more alkaline than sodium methoxide and sodium ethoxide, which can not only make the reaction conversion complete, reduce the generation of by-products, but also facilitate impurity removal, avoiding the loss caused by the distillation step.

[0027] Third, the impurity removal of this scheme adopts the method of quenching acidification and recrystallization. Quenching avoids the white smoke generated in the acidification process from polluting the environment and endangering the operators. Acidification can remove the catalyst added to the reaction, and recrystallization removes excess solvents and other impurities to improve product purity.

[0028] This scheme provides a pilot-scale preparation method for β-diketone compounds, which is of great significance for the large-scale production of blue light absorbing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] In the attached figure:

[0032] Figure 1 : Schematic diagram of the etherification reaction between 4-hydroxyacetophenone and n-butyl bromide. Hydroxyacetophenone (A) and n-butyl bromide (B) are synthesized into 1-(4-butoxyphenyl)ethanone (C) under the catalysis of potassium carbonate.

[0033] Figure 2: Schematic diagram of the condensation reaction of methyl bibenzoate and 4-butoxyacetophenone. Methyl bibenzoate (A) and 1-(4-butoxyphenyl)ethanone (B) are synthesized into 4-([1,1'-biphenyl]-4-yl)-1-(4-butoxyphenyl)butane-1,3-dione (C) under the catalysis of tert-butanol.

[0034] Figure 3 : Detection results of blue light absorbance at different concentrations. DETAILED DESCRIPTION

[0035] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention all belong to the scope of protection of the present invention. Unless otherwise specified, the experimental materials, reagents, instruments, etc. used in the examples of the present invention are all commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0036] A method for preparing a blue light absorbing material, characterized in that it comprises the following steps:

[0037] Dissolve p-hydroxyacetophenone and alkyl halide in a solvent, add a catalyst while stirring, and keep the temperature at 88°C for 5 hours to obtain alkoxyacetophenone;

[0038] Dissolve methyl phenylformate and potassium tert-butoxide in a solvent, add alkoxyacetophenone while stirring, and react for 1 hour;

[0039] The reaction system is poured into water for quenching and acidification, and 1-phenyl-3-alkoxyphenyl-1,3-propanedione compounds, i.e., blue light absorbing materials, are obtained through washing, filtering and recrystallization.

[0040] Example 1 Potassium carbonate catalyzed etherification reaction

[0041] 6807 g (50 mol) of p-hydroxyacetophenone, 6988 g (51 mol) of n-butyl bromide and 6.8 liters of N,N-dimethylformamide were added to the reaction kettle, and the reaction kettle was transferred to a water bath, and the reaction system was continuously stirred.

[0042] Under stirring, 7314 g (53 mol) of potassium carbonate was slowly added dropwise, and the water bath temperature was prevented from exceeding 75°C during the addition.

[0043] The reaction system was continuously stirred until the temperature in the reactor exceeded 60°C, then the water bath was turned off, and stirring was continued until the temperature in the reactor reached 88°C, then the water bath was turned on, and the temperature was maintained at 88°C for 5 hours, wherein the reaction progress was monitored by TLC every 1 hour.

[0044] When TLC showed that the reaction was complete, the water bath was turned off and the reaction system was cooled to room temperature.

[0045] The reaction system was transferred to a suction filter, potassium carbonate residue was removed by filtration, and the obtained filtrate was transferred to a rotary evaporator for 30 minutes to obtain a light yellow transparent liquid, namely 1-(4-butoxyphenyl)ethanone, with a purity of 99%.

[0046] like Figure 1 As shown, in the etherification reaction, hydroxyacetophenone (A) and n-butyl bromide (B) are synthesized into 1-(4-butoxyphenyl)ethanone (C) under the catalysis of potassium carbonate.

[0047] Comparative Example 1 Etherification reaction catalyzed by sodium hydroxide

[0048] 6807 g (50 mol) of p-hydroxyacetophenone, 6988 g (51 mol) of n-butyl bromide and 6.8 liters of N,N-dimethylformamide were added to the reaction kettle, and the reaction kettle was transferred to a water bath, and the reaction system was continuously stirred.

[0049] Under stirring, 2120 g (53 mol) of sodium hydroxide was slowly added dropwise. Due to the violent exothermic reaction, the temperature of the water bath could not be kept below 75° C. during the addition.

[0050] The reaction system was continuously stirred and the reaction temperature was maintained at 88° C. for 5 hours, wherein the reaction progress was monitored by TLC every 1 hour.

[0051] When TLC showed that the reaction was complete, the water bath was turned off and the reaction system was cooled to room temperature.

[0052] The reaction system was transferred to a suction filter, potassium carbonate residue was removed by filtration, and the obtained filtrate was transferred to a rotary evaporator for 30 minutes to obtain a light yellow transparent liquid, namely 1-(4-butoxyphenyl)ethanone, with a purity of 54%.

[0053] Example 2 Potassium tert-butoxide catalyzed condensation reaction

[0054] 6788 g (32 mol) of methyl bibenzoate, 4309 g (38.4 mol) of potassium tert-butoxide and 27.152 liters of N,N-dimethylformamide were added to the reactor of Example 1, and the reactor was transferred to a water bath, and the reaction system was continuously stirred.

[0055] Under stirring, 8651 g (45 mol) of 1-(4-butoxyphenyl)ethanone was slowly added dropwise. After the addition was completed, stirring was continued for 1 hour. The reaction progress was monitored by TLC every 15 minutes.

[0056] When TLC showed that the reaction was complete, the water bath was turned off and the reaction system was cooled to room temperature.

[0057] like Figure 2 As shown, in the condensation reaction, methyl biphenylcarboxylate (A) and 1-(4-butoxyphenyl)ethanone (B) are synthesized under the catalysis of tert-butyl alcohol to synthesize 4-([1,1'-biphenyl]-4-yl)-1-(4-butoxyphenyl)butane-1,3-dione (C), which is the blue light absorbing material of this scheme.

[0058] The reaction system was transferred to a quenching barrel containing cold water. Except for the stirring port, the barrel mouth was sealed with a film. After piercing the film with a tube, concentrated hydrochloric acid was slowly added from the tube. Stirring was continued for acidification. When the pH value was 5 with a pH meter, the addition of concentrated hydrochloric acid was stopped. The system was transferred to a suction filter and filtered to obtain a filter cake.

[0059] The filter cake was washed with water until the pH of the washing liquid was 7, and the filter residue was obtained by suction filtration. Methanol was then added and stirred for half an hour to disperse the filter residue. The solid product was obtained by suction filtration. The solid product was washed with methanol repeatedly until the filtrate was clear and free of impurities.

[0060] The solid product was heated and dissolved with 35.77 liters of methanol, then cooled and refluxed, filtered, and the recrystallization step was repeated until the methanol reflux liquid was clear and transparent. The final product obtained was 10.1 kg of light orange-red solid after drying, with a purity of 95.8% and a recrystallization recovery rate of 84.7%.

[0061] Comparative Example 2 Sodium Methanol Catalyzed Condensation Reaction

[0062] 6788 g (32 mol) of methyl bibenzoate, 2074 g (38.4 mol) of potassium tert-butoxide and 27.152 liters of N,N-dimethylformamide were added to the reactor of Example 1, and the reactor was transferred to a water bath, and the reaction system was continuously stirred.

[0063] Under stirring, 8651 g (45 mol) of 1-(4-butoxyphenyl)ethanone was slowly added dropwise. After the addition was completed, stirring was continued for 1 hour. The reaction progress was monitored by TLC every 15 minutes.

[0064] When TLC showed that the reaction was complete, the water bath was turned off and the reaction system was cooled to room temperature.

[0065] The reaction system was transferred to a quenching barrel containing cold water. Except for the stirring port, the barrel mouth was sealed with a film. After piercing the film with a tube, concentrated hydrochloric acid was slowly added from the tube. Stirring was continued for acidification. When the pH value was 5 with a pH meter, the addition of concentrated hydrochloric acid was stopped. The system was transferred to a suction filter and filtered to obtain a filter cake.

[0066] The filter cake was washed with water until the pH of the washing liquid was 7, and the filter residue was obtained by suction filtration. Methanol was then added and stirred for half an hour to disperse the filter residue. The solid product was obtained by suction filtration. The solid product was washed with methanol repeatedly until the filtrate was clear and free of impurities.

[0067] The solid product was heated and dissolved with 35.77 liters of methanol, then cooled and refluxed, filtered, and the recrystallization step was repeated until the methanol reflux liquid was clear and transparent. The final product was 7.2 kg of light orange-red solid after drying, with a purity of 70.1% and a recrystallization recovery rate of 80.7%.

[0068] Example 3 Testing the blue light absorption ability of the product

[0069] 10, 20, 30, 50, 100, and 200 mg of the final product obtained in Example 2 were weighed respectively, placed in a 10-ml volumetric flask, and dichloromethane was added dropwise to make the volume to 10 ml. The mixture was shaken thoroughly to obtain samples with concentrations of 1, 2, 3, 5, 10, and 20 mg / ml, respectively.

[0070] Take 0.5 ml of each concentration of sample and dichloromethane respectively, evenly spread them on a colorless and transparent round glass slide, and then place the glass slide in an oven at 60°C for 30 minutes to obtain a glass slide with the sample to be tested evenly attached and a glass slide without the sample attached (blank control).

[0071] Turn on the UV lamp, set the wavelength to 405 nanometers, place a light intensity meter 10 cm away from the light source to obtain light intensity readings, place the glass slides of the samples to be tested and the glass slides of the blank controls 5 cm away from the light source, and record the light intensity readings measured each time.

[0072] The light intensity of the blank control slide is 100% (i.e. the blue light absorption rate is 0%), and the formula is:

[0073] Blue light absorption rate = (1-slide light intensity of the sample to be tested / slide light intensity of the blank control) * 100%

[0075] Calculate the absorption capacity of the glass slide of the sample to be tested under 405 nm light.

[0076] The test results are shown in Table 1

[0077] Table 1 Detection results of blue light absorption rate at different concentrations

[0078]

[0079] From Table 1 and Figure 3It can be seen that when the concentration is lower than 3 mg / ml, the blue light absorption rate of the product is less than 80%. When the concentration is greater than or equal to 3 mg / ml, the blue light absorption rate of the product exceeds 80%, which meets the market demand for anti-blue light products. With the continuous increase in concentration, the blue light absorption rate of the product only increases slightly, indicating that only milligram-level products can meet production needs, which is conducive to saving costs in production.

[0080] At the same time, by comparing Example 1 and Comparative Example 1, it can be seen that compared with sodium hydroxide, the product obtained by the etherification reaction catalyzed by potassium carbonate has higher purity, and the reaction does not have problems such as gelatinization caused by violent exotherm.

[0081] By comparing Example 2 and Comparative Example 2, it can be seen that compared with sodium methoxide, the product yield obtained by catalyzing the condensation reaction with potassium tert-butoxide is higher and has less impurities.

[0082] Two comparative experiments show that using potassium carbonate or sodium carbonate as a catalyst for the etherification reaction and using tert-butanol as a condensation agent for the condensation reaction can significantly optimize the preparation process of β-diketone compounds, effectively solving the problems of low reaction conversion rate, low product purity, low yield, and serious pollution in the reaction process in the existing preparation scheme, and has high application significance for large-scale production.

[0083] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for preparing a blue light absorbing material, characterized in that: The following steps are involved: Dissolve p-hydroxyacetophenone and alkyl halide in a solvent, stir, add a catalyst, and keep the temperature at 88-90° C. for 4.5-5 hours to obtain alkoxyacetophenone; Dissolve methyl phenylformate and potassium tert-butoxide in a solvent, add alkoxyacetophenone while stirring, and react for 1-2 hours to obtain a reaction system; The reaction system was poured into water to quench, and then acidified 、 Washing, filtering and recrystallizing to obtain 1-phenyl-3-alkoxyphenyl-1,3-propanedione compounds, i.e., blue light absorbing materials; Wherein, the catalyst is sodium carbonate or potassium carbonate.

2. The preparation method according to claim 1, characterized in that: The alkyl halide includes one of propyl bromide, butyl bromide, pentane bromide, hexyl bromide and benzyl bromide.

3. The preparation method according to claim 1, characterized in that: The solvent is N,N-dimethylformamide.

4. The preparation method according to claim 1, characterized in that: The molar ratio of p-hydroxyacetophenone, alkyl halide and catalyst is 1:1-1.2:1-1.

5.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the methyl benzoate, tert-butyl alcohol and alkoxyacetophenone is 1:1-1.5:2.25-2.

5.

6. The preparation method according to claim 1, characterized in that: The temperature is controlled below 75° C. when the catalyst is added.

7. The preparation method according to claim 1, characterized in that: The pH of the reaction system after acidification is 5-6.

8. The preparation method according to claim 1, characterized in that: The pH of the reaction system after washing is 6-8.

9. The preparation method according to claim 1, characterized in that: The solvent used in the recrystallization is methanol.

10. The preparation method according to claim 1, characterized in that: The blue light absorbing material has the structural formula 1, Among them, R1 includes one of propyl, butyl, pentyl, hexyl and benzyl, and R2 includes one of phenyl and benzyl.

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