An aging-resistant photochromic dye and its preparation method

Abstract

This invention discloses an age-resistant photochromic dye and its preparation method, belonging to the fields of fine chemical synthesis and optical functional materials technology. In this invention, naphthalene ketone is reacted with succinate and acetic anhydride to generate a hyperconjugated naphthol derivative. The naphthol derivative then reacts with the aforementioned hydroxyl-functionalized diarylkynyl alcohol to generate a hyperconjugated naphthopyran compound. This synthetic process is easy to operate. Furthermore, the obtained hyperconjugated naphthopyran compound exhibits a rapid fading rate and good age resistance, making it suitable for applications in photochromic lenses, textiles, anti-counterfeiting, coatings, and other fields.

Description

Technical Field

[0001] This invention relates to an aging-resistant photochromic dye and its preparation method, belonging to the technical fields of fine chemical synthesis and optical functional materials. Background Technology

[0002] Photochromic dyes undergo a molecular structural transformation from one state (or form) to another upon exposure to radiation of a specific wavelength, with each state exhibiting a characteristic absorption spectrum. For example, many photochromic compounds transform from an inactive (e.g., whitish or essentially colorless) state to an activated (e.g., colored) state upon exposure to ultraviolet radiation. Organic photochromic compounds, such as spiropyrans, naphthopyrans, spiroxazines, azobenzenes, diarylethylenes, and benzoic anhydrides, are widely used in lenses, plastic products, coatings, textiles, and inks. These materials undergo photoisomerization under ultraviolet light irradiation, accompanied by changes in their absorption and emission properties. The molecular structure and properties are restored upon removal of ultraviolet or visible light stimulation. However, photochromic dyes are susceptible to aging; prolonged exposure to light can cause discoloration and fading, reducing the fading rate and ultimately causing the coating to gradually lose its photochromic properties.

[0003] The paper "Development Trends of Organic Photochromic Diarylethylene Dyes" (Zhu Shiqin, Li Mengqi, Zhu Weihong. Development Trends of Organic Photochromic Diarylethylene Dyes [J]. Nature Journal, 2018, 40(2):79-89.) discloses a class of diarylethylene-type photochromic dyes, which exhibit excellent bistableness and fatigue resistance. It is evident that the aging resistance of photochromic dyes is an aspect that needs improvement, requiring the design of novel structures to enable photochromic dyes to possess aging resistance properties. Summary of the Invention

[0004] Technical issues

[0005] Photochromic dyes are subject to aging. Prolonged exposure to natural light can cause negative effects such as discoloration and fading, and reduce the fading rate, eventually causing the coating to gradually lose its photochromic properties. Therefore, it is necessary to develop new photochromic dye structures to address the aging problem of photochromic dyes.

[0006] Technical content

[0007] To address the aforementioned problems, this invention designs and synthesizes a hyperconjugated naphthopyran compound by modifying the molecular structure of naphthopyran. This compound can achieve a rapid, reversible photochromic effect from colorless to colored, while also exhibiting excellent aging resistance. This color-changing dye can be used in multiple anti-counterfeiting materials, photochromic glasses, photochromic textiles and clothing, and photochromic inks.

[0008] This invention provides an aging-resistant naphthopyran compound, wherein the naphthopyran compound is shown in Formula I below:

[0009]

[0010] In Formula I, R1, R2, R3, R4, R5, R6, R7 and R8 are each independently selected from hydrogen, methyl, ethyl, methoxy, ethoxy, isopropoxy, trifluoromethyl, halogen, -N(CH3)2, -N(CH2CH3)2, methyl carboxylate (-COOMe), ethyl carboxylate (-COOEt) or benzene ring.

[0011] Furthermore, the halogen is fluorine, chlorine, or bromine.

[0012] Furthermore, R1, R2, R3, R4, R5, R6, R7, and R8 can be the same, partially the same, or completely different.

[0013] Specifically, in Formula I, R1, R2, R3, R4, R5, and R6 are hydrogen atoms, and R7 and R8 are methyl atoms.

[0014] Specifically, in Formula I, R3 is methyl, R5 and R6 are methoxy, R1, R2 and R4 are hydrogen, and R7 and R8 are methyl.

[0015] Specifically, in Formula I, R5 and R6 are methoxy groups, R7 and R8 are ethyl groups, and R1, R2, R3, and R4 are hydrogen groups.

[0016] Specifically, in Formula I, R5 and R6 are methyl groups, R7 and R8 are benzene rings, and R1, R2, R3, and R4 are hydrogen atoms.

[0017] The present invention also provides a method for preparing the above-mentioned naphthopyran compound, the method comprising the following steps:

[0018]

[0019] (1) After dissolving succinate and compound A in an organic solvent, potassium tert-butoxide is added and reacted at 70-110℃ for 12-30h. After the reaction is completed, water is added and the mixture is allowed to stand to separate into layers. The aqueous layer is extracted with an organic solvent. The pH of the aqueous phase obtained after extraction is adjusted to 2-3. The acidified aqueous phase is then extracted with an organic solvent. The organic phase obtained after extraction is then evaporated to dryness, which yields compound B.

[0020]

[0021] (2) Compound B was reacted with acetic anhydride at 90-120°C. After the reaction was completed, a saturated alkaline solution was added, followed by extraction with an organic solvent. The extracted organic phase was dehydrated, filtered, and evaporated to dryness to obtain a crude product. The crude product was then recrystallized to obtain compound C.

[0022]

[0023] (3) Compound C was reacted with an alkaline solution, extracted, washed with water to obtain the organic phase, separated, and the organic phase obtained after separation was dehydrated and evaporated to dryness to obtain crude product D.

[0024]

[0025] (4) Dissolve compounds D and E in an organic solvent, add an acidic catalyst, stir the reaction at 30-100℃ for 1-12 hours, then add water to separate the layers, and separate the organic phase by column chromatography to obtain compound F.

[0026]

[0027] (5) Compound F is dissolved in an organic solvent, and an organomagnesium compound or an organolithium compound is added at -20 to -10 degrees Celsius. The mixture is stirred at 20 to 25 degrees Celsius for 10 to 20 hours to quench the reaction. After the layers are separated, the organic phase is washed with water, dried by rotary evaporation, recrystallized, and filtered to obtain crude product G.

[0028]

[0029] (6) Dissolve compound G in an organic solvent, add an acidic catalyst, stir the reaction at 80-120°C for 5-12 hours, then remove the solvent and separate by column chromatography to obtain compound H.

[0030] Furthermore, in the above reaction formula, R1, R2, R3, R4, R5, R6, R7 and R8 are independently selected from hydrogen, methyl, ethyl, methoxy, ethoxy, isopropoxy, trifluoromethyl, halogen, -N(CH3)2, -N(CH2CH3)2, methyl carboxylate (-COOMe), ethyl carboxylate (-COOEt) or benzene ring.

[0031] Furthermore, the halogen is fluorine, chlorine, or bromine.

[0032] Furthermore, in step (1), the molar ratio of succinate to compound A is 4:1 to 1.5:1.

[0033] Furthermore, in step (1), the molar ratio of potassium tert-butoxide to compound A is 5:1 to 1.5:1.

[0034] Furthermore, in step (1), the organic solvent is one or more of toluene, ethyl acetate, acetone, petroleum ether, acetonitrile, n-hexane, diethyl ether, chloroform, dichloromethane, and dichloroethane.

[0035] Furthermore, using mL as the volume unit, the volume of the organic solvent used in the reaction and extraction in step (1) is 10 to 1000 times the molar amount of the compound; the molar amount of the compound is the sum of the molar amounts of succinate, compound A and potassium tert-butoxide.

[0036] Furthermore, using mL as the volume unit, the volume of water in step (1) is 10 to 1000 times the molar amount of the compound; the molar amount of the compound is the sum of the molar amounts of succinate, compound A and potassium tert-butoxide.

[0037] Furthermore, in step (2), the mass ratio of acetic anhydride to compound D is 15:1 to 5:1.

[0038] Furthermore, the alkali in step (2) includes one or more of NaHCO3, KHCO3, K2CO3, and Na2CO3.

[0039] Furthermore, in step (2), the amount of saturated alkaline solution used must be sufficient to ensure that acetic anhydride is completely decomposed.

[0040] Furthermore, in step (2), the organic solvent is one or more of toluene, ethyl acetate, acetone, petroleum ether, acetonitrile, n-hexane, diethyl ether, chloroform, dichloromethane, and dichloroethane.

[0041] Furthermore, using mL as the volume unit, the volume of the organic solvent in step (2) is 10 to 1000 times the molar amount of the compound; the molar amount of the compound is the molar amount of compound B.

[0042] Furthermore, the alkali in the alkaline solution in step (3) includes one or more of NaHCO3, KHCO3, K2CO3, and Na2CO3.

[0043] Furthermore, in step (3), the mass concentration of alkali in the alkaline solution is 10–20 wt%.

[0044] Furthermore, in step (3), the molar ratio of compound C to the volume of the alkaline solution is 1 mmol: 5-20 mL.

[0045] Furthermore, the acid catalyst in step (4) includes one or more of the following: methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dodecylsulfonic acid, pyridine p-toluenesulfonic acid, acidic alumina, heteropoly acid, and phosphoric acid.

[0046] Furthermore, in step (4), the molar ratio of compound E to compound D is 1.5:1 to 1:1.

[0047] Furthermore, in step (4), the amount of acid catalyst used is 2 to 10% of the molar amount of compound D.

[0048] Furthermore, in step (4), the organic solvent is one or more of toluene, ethyl acetate, acetone, petroleum ether, acetonitrile, n-hexane, diethyl ether, chloroform, dichloromethane, and dichloroethane.

[0049] Furthermore, using mL as the volume unit, the volume of the organic solvent in step (4) is 10 to 1000 times the molar amount of the compound; the molar amount of the compound is the sum of the molar amounts of compound D, compound E and acid catalyst.

[0050] Furthermore, in step (5), the organomagnesium compound includes one or more of methyl magnesium bromide, methyl magnesium chloride, ethyl magnesium bromide, ethyl magnesium chloride, propyl magnesium chloride, propyl magnesium bromide, phenyl magnesium bromide, phenyl magnesium chloride, and benzyl magnesium chloride; and the organolithium compound includes one or more of n-butyllithium, phenyl lithium, methyl lithium, and propyl lithium.

[0051] Furthermore, in step (5), the molar ratio of compound F to organomagnesium compound or organolithium compound is 1:2 to 1:10.

[0052] Furthermore, the acid catalyst in step (6) includes one or more of the following: methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dodecylsulfonic acid, pyridine p-toluenesulfonic acid, acidic alumina, heteropoly acid, and phosphoric acid.

[0053] Furthermore, in step (6), the amount of acid catalyst used is 2 to 10% of the molar amount of compound G.

[0054] Furthermore, in step (6), the organic solvent is one or more of toluene, ethyl acetate, acetone, petroleum ether, acetonitrile, n-hexane, diethyl ether, chloroform, dichloromethane, and dichloroethane.

[0055] Furthermore, using mL as the volume unit, the volume of the organic solvent in step (6) is 10 to 1000 times the molar amount of the compound; the molar amount of the compound is the sum of the molar amounts of compound G and the acid catalyst.

[0056] The invention relates to the application of the hyperconjugated naphthopyran compound in the fields of photochromic lenses, textiles, anti-counterfeiting, and coatings.

[0057] Beneficial effects

[0058] In this invention, naphthalene ketones are reacted with succinate and acetic anhydride to generate hyperconjugated naphthol derivatives. These naphthol derivatives then react with the aforementioned hydroxyl-functionalized diarylkynyl alcohols to generate hyperconjugated naphthopyran compounds. This synthetic process is easy to operate. Furthermore, the resulting hyperconjugated naphthopyran compounds exhibit rapid fading and excellent aging resistance; the fading half-life can be controlled to within 70 seconds, and they remain unfaded even after 48 hours of UV aging. Attached Figure Description

[0059] Figure 1 Synthetic route diagram for hyperconjugated naphthopyran compounds.

[0060] Figure 2 The image shows the UV absorption spectrum of compound H in Example 1. Detailed Implementation

[0061] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0062] Source of raw materials

[0063] Unless otherwise specified, all compounds used in the examples are commercially available products that can be purchased through online reagent platforms.

[0064] Example 1

[0065] Synthesis of compound H:

[0066]

[0067]

[0068] Step 1: Dimethyl succinate (20 mmol) and compound A (10 mmol) were dissolved in toluene (20 mL), and potassium tert-butoxide (20 mmol) was added. The reaction was carried out at 100 °C for 20 h. After the reaction was completed by TLC spot detection, 30 mL of water was added to decompose the potassium tert-butoxide. Then, the reaction solution was rotary evaporated to remove part of the solvent. 30 mL of water was added to the rotary evaporated reaction solution. After standing and separation, the aqueous layer was taken and extracted three times with a total of 60 mL of dichloromethane. The aqueous phase after extraction was acidified to pH 2 with dilute hydrochloric acid. The acidified aqueous phase was then extracted three times with a total of 120 mL of ethyl acetate. The ethyl acetate was combined and evaporated to dryness to obtain compound B.

[0069] Step 2: The compound B (2g) obtained above was mixed with acetic anhydride (20mL) and reacted at 110℃. The reaction was detected by TLC. After the reaction was completed, saturated sodium bicarbonate solution was added to decompose the acetic anhydride. Then, the reaction solution was extracted three times with a total of 50mL of ethyl acetate. The organic phases were then combined and washed three times with saturated brine. The organic phase was then dried with anhydrous Na2SO4, filtered and evaporated to dryness to obtain the crude product. The crude product was then recrystallized twice with a 3:1 mixture of petroleum ether and ethyl acetate to obtain compound C.

[0070] Step 3: Dissolve compound C (10 mmol) in 20 mL of methanol, add 15 mL of 15% sodium carbonate solution, stir at 45 °C for 5 h, evaporate the solvent, add 30 mL of ethyl acetate, wash twice with 50 mL of brine each time, then let stand and separate the liquid. Take the organic phase and remove water with anhydrous Na2SO4. After filtration, separate the product by column chromatography (eluent is ethyl acetate and petroleum ether in a volume ratio of 1:10, retain the product with an Rf value of 0.4) to obtain compound D.

[0071] Step 4: Dissolve compounds D (10 mmol) and E (11 mmol) in 20 mL of dichloromethane, add p-toluenesulfonic acid catalyst (0.5 mmol), stir and react at 45 °C for 3 h. After the reaction is completed by TLC spot detection, add a total of 100 mL of deionized water to wash three times, let stand and separate the liquids, take the organic phase and remove the solvent by rotary evaporation under reduced pressure, and then separate the product by column chromatography (the eluent is ethyl acetate and petroleum ether in a volume ratio of 1:8, retain the product with an Rf value of 0.6) to obtain compound F.

[0072] Step 5: Dissolve compound F (10 mmol) in 40 mL of anhydrous tetrahydrofuran, stir at -10 °C and add 20 mL of 3 M methyl magnesium chloride tetrahydrofuran solution, stir at 25 °C for 12 hours, and after the reaction is detected by TLC, add 40 mL of saturated ammonium chloride solution to quench it, let stand, take the organic phase and wash it three times with a total of 150 mL of saturated brine, separate the organic phase and evaporate to dryness, then recrystallize twice with a 3:1 mixture of n-hexane and ethyl acetate, filter, dry to obtain compound G.

[0073] Step 6: Dissolve compound G (10 mmol) in 50 mL of toluene, add p-toluenesulfonic acid (0.5 mmol), reflux and stir. After the reaction is detected by TLC, evaporate the solution to dryness, wash with 50 mL of methanol, filter to collect the solid, and then separate the product by column chromatography (eluent is ethyl acetate and petroleum ether in a volume ratio of 1:6, retain the product with an Rf value of 0.6) to obtain compound H.

[0074] The UV absorption spectrum of compound H is shown in [reference needed]. Figure 2 .

[0075] Example 2

[0076] The synthesis steps in this embodiment are the same as in Example 1, except that compound A in step 1 is replaced with the same molar amount of a compound having the following structure:

[0077]

[0078] Then replace compound E in step 4 with the same molar amount of a compound having the following structure:

[0079]

[0080] The final compound I was synthesized, and its chemical formula is shown below:

[0081]

[0082] Example 3

[0083] The synthesis steps in this embodiment are the same as in Example 1, except that compound E in step 4 is replaced with the same molar amount of a compound having the following structure:

[0084]

[0085] In step 5, methyl magnesium bromide is replaced with an equal molar amount of propyl magnesium chloride, ultimately synthesizing compound J, whose chemical formula is shown below:

[0086]

[0087] Example 4

[0088] The synthesis steps in this embodiment are the same as in Example 1, except that compound E in step 4 is replaced with the same molar amount of a compound having the following structure:

[0089]

[0090] Next, replace the methyl magnesium bromide in step 5 with the same molar amount of phenyl magnesium chloride to finally synthesize compound K, the chemical formula of which is shown below:

[0091]

[0092] Comparative Example 1

[0093] The synthesis steps are the same as in Example 1, except that compound A in step 1 is replaced with a diaryl ketone, the structural formula of which is as follows:

[0094]

[0095] The final synthesis of conventional naphthopyran compound M is shown below:

[0096]

[0097] Comparative Example 2

[0098] The synthesis steps are the same as in Example 1, except that compound A in step 1 is replaced with a ketone with the following structure:

[0099]

[0100] The final synthesis was a conventional non-hyperconjugated naphthopyran compound N, the chemical formula of which is shown below:

[0101]

[0102] Lenses were fabricated from the compounds obtained in Examples 1-4 and Comparative Examples 1-2. The preparation process involved 4 parts of ethoxybisphenol A dimethacrylate (EBPDMA, EO / phenol = 1.3), 1 part of poly(ethylene glycol) 400 dimethacrylate (PEGDMA), and 0.4 wt% AIBN (free radical initiator) relative to the total mass, with the photochromic compound content being 1.5% of the total mass. This mixture was added to a mold and thermocured at 110°C for 2 hours. The thickness of the produced test lenses was approximately 2 mm. The lenses were irradiated with a 365 nm ultraviolet light source, and the color-changing properties and fading half-life T of the lens samples were recorded. 1 / 2 The yellowing of the samples after UV aging in the aging test chamber for 48 hours was also compared, and the data were recorded in Table 1 below:

[0103] Table 1

[0104] sample 30s (Ta1%) <![CDATA[T 1 / 2 (S)]]> Yellowing condition Example 1 22.8 49 No significant changes Example 2 21.3 58 No significant changes Example 3 20.6 36 No significant changes Example 4 19.5 64 No significant changes Comparative Example 1 48.2 115 Slightly yellowing Comparative Example 2 37.1 254 Slightly yellowing

[0105] Ta represents the transmittance after 30 seconds of ultraviolet irradiation. The smaller the value, the deeper the color change. 1 / 2 This is the fading half-life; the smaller the value, the faster the fading.

[0106] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. An aging-resistant naphthopyran compound, characterized in that, The naphthopyran compound is shown in Formula I below: Formula I In Formula I, R1, R2, R3, R4, R5, R6, R7 and R8 are each independently selected from hydrogen, methyl, ethyl, methoxy, ethoxy, isopropoxy, trifluoromethyl, halogen, -N(CH3)2, -N(CH2CH3)2, -COOMe, -COOEt or phenyl.

2. The naphthopyran compound according to claim 1, characterized in that, In Formula I, R1, R2, R3, R4, R5, and R6 are hydrogen atoms, and R7 and R8 are methyl atoms.

3. The naphthopyran compound according to claim 1, characterized in that, In Formula I, R3 is methyl, R5 and R6 are methoxy, R1, R2 and R4 are hydrogen, and R7 and R8 are methyl.

4. The naphthopyran compound according to claim 1, characterized in that, In Formula I, R5 and R6 are methoxy groups, R7 and R8 are ethyl groups, and R1, R2, R3, and R4 are hydrogen groups.

5. The naphthopyran compound according to claim 1, characterized in that, In Formula I, R5 and R6 are methyl groups, R7 and R8 are phenyl groups, and R1, R2, R3, and R4 are hydrogen groups.

6. A method for preparing the naphthopyran compound according to any one of claims 1 to 5, characterized in that, The preparation method includes the following steps: (1) After dissolving succinate and compound A in an organic solvent, potassium tert-butoxide is added and reacted at 70~110°C for 12-30h. After the reaction is completed, water is added and the mixture is allowed to stand to separate into layers. The aqueous layer is extracted with an organic solvent. The pH of the aqueous phase obtained after extraction is adjusted to 2~3. The acidified aqueous phase is then extracted with an organic solvent. The organic phase obtained after extraction is then evaporated to dryness to obtain compound B. (2) Compound B was reacted with acetic anhydride at 90~120°C. After the reaction was completed, a saturated alkaline solution was added, followed by extraction with an organic solvent. The extracted organic phase was dehydrated, filtered, and evaporated to dryness to obtain a crude product. The crude product was then recrystallized to obtain compound C. (3) Take compound C and react it with alkaline solution, extract and wash the organic phase obtained by extraction with water, separate the liquid and liquid, take the organic phase obtained after separation to remove water and evaporate to dryness to obtain crude product D; (4) Dissolve compounds D and E in an organic solvent, add an acidic catalyst, stir the reaction at 30~100°C for 1-12 h, then add water to separate the layers, and separate the organic phase by column chromatography to obtain compound F; (5) Compound F is dissolved in an organic solvent, and an organomagnesium compound or an organolithium compound is added at -20 to -10 degrees Celsius. The mixture is stirred at 20 to 25 degrees Celsius for 10 to 20 hours to quench the reaction. After separation, the organic phase is washed with water, dried by rotary evaporation, recrystallized, and filtered to obtain crude product G. (6) Dissolve compound G in an organic solvent, add an acidic catalyst, stir the reaction at 80~120°C for 5-12 h, then remove the solvent and separate by column chromatography to obtain compound H.

7. The preparation method according to claim 6, characterized in that, In step (1), the molar ratio of succinate to compound A is 4:1 to 1.5:1; in step (1), the molar ratio of potassium tert-butoxide to compound A is 5:1 to 1.5:1; in step (2), the mass ratio of acetic anhydride to compound B is 15:1 to 5:

1.

8. The preparation method according to claim 6, characterized in that, In step (4), the acid catalyst includes one or more of the following: methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dodecylsulfonic acid, pyridine p-toluenesulfonic acid, acidic alumina, heteropoly acid, and phosphoric acid; the molar ratio of compound E to compound D in step (4) is 1.5:1 to 1:1; the amount of acid catalyst used in step (4) is 2 to 10% of the molar amount of compound D.

9. The preparation method according to claim 6, characterized in that, In step (5), the organomagnesium compound includes one or more of methyl magnesium bromide, methyl magnesium chloride, ethyl magnesium bromide, ethyl magnesium chloride, propyl magnesium chloride, propyl magnesium bromide, phenyl magnesium bromide, phenyl magnesium chloride, and benzyl magnesium chloride; the organolithium compound includes one or more of n-butyllithium, phenyl lithium, methyl lithium, and propyl lithium; the molar ratio of compound F to organomagnesium compound or organolithium compound in step (5) is 1:2 to 1:10; the acid catalyst in step (6) includes one or more of methanesulfonic acid, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dodecylsulfonic acid, pyridine p-toluenesulfonic acid, acidic alumina, heteropoly acid, and phosphoric acid; the amount of acid catalyst used in step (6) is 2 to 10% of the molar amount of compound G.

10. The use of the naphthopyran compound according to any one of claims 1 to 5 in the fields of photochromic lenses, textiles, anti-counterfeiting or coatings.

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