A novel high-sulfur-content photopolymerizable high-refractive monomer and a preparation method thereof

Abstract

The application relates to the technical field of organic chemistry, in particular to a novel high-sulfur-content photopolymerizable high-refraction monomer and a preparation method thereof. The high-refraction structure has not been reported in the prior art. Dithiolane is used as a connecting unit, combined with a series of structural units with high molar refraction and photocurable groups, so that the material refraction is improved, the monomer is in a liquid state, the monomer is easy to dissolve, the solid content is full, and pollution is avoided during the polymerization process; the structure contains a rigid large conjugated aromatic ring and dithiolane methyl mercaptan with high sulfur content, so that the material dispersion is reduced, and certain physical properties are endowed.

Description

Technical Field

[0001] This invention relates to the field of organic chemistry, specifically to a novel high-sulfur, photopolymerizable, high-refractive-index monomer and its preparation method. Background Technology

[0002] Optical resins are increasingly favored due to their lightweight, impact resistance, ease of processing and molding, dyeability, and excellent optical properties. They are gradually replacing inorganic optical materials and are widely used in the manufacturing of optical fiber communication materials, LED packaging, resin lenses, precision lenses, and functional coatings. The continuous development of these optical devices is closely related to the development of high refractive index (RI) materials. The higher the refractive index, the thinner the material can achieve the same display effect. Functional materials with higher refractive indices are more suitable for the manufacture of advanced optical devices. However, the main molding method for high refractive index resins is thermosetting, which suffers from slow molding, high energy consumption, and environmental problems. Photocuring allows materials to cure rapidly under light, offering advantages such as high efficiency, precision, environmental friendliness, and energy saving. However, the optical materials widely used in the market are currently mainly low-refractive-index acrylate monomers, which have high viscosity, low refractive index, and less than ideal overall performance, limiting their application range. To address the limitations of existing technologies, this invention introduces dithiocyclopentane groups into the molecular structure, which increases the refractive index of the material while making the monomer liquid. This avoids the use of solvents during polymerization, making it environmentally friendly and cost-effective. It can effectively compensate for the shortcomings of traditional acrylate monomers, giving it great application prospects in the manufacturing of micro-nano structures such as electronic encapsulation adhesives, optical devices, and printed circuits. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art: to provide a novel high-sulfur-content photopolymerizable high-refractive-index monomer and its preparation method.

[0004] To address the above problems, the technical solution provided by this invention is as follows:

[0005] A novel high-sulfur, photopolymerizable, high-refractive-index monomer has the following structural formula:

[0006]

[0007] in,

[0008] R1 is selected from -H, -CH3,

[0009] R2 is selected from

[0010] Preferably, the method includes the following steps:

[0011] (1) Using SH-R2-SH thiol compounds as raw materials, react with epichlorohydrin to form epoxy group compounds, and then carry out cyclosulfidation reaction with NH4SCN to obtain cyclosulfide group compounds.

[0012] (2) The cyclic sulfur group compound reacts with sodium hydrosulfide and hydrogen sulfide to give two dithiol group compounds;

[0013] (3) The product of step 2 reacts with dihydroxydithiane to obtain a compound with a dithiocyclopentane methanethiol group.

[0014] (4) The product of step 3 was substituted with (meth)acrylic anhydride under alkaline catalysis to prepare the corresponding high-refractive-index monomer;

[0015] The reaction formula is as follows:

[0016]

[0017] Preferably, in step 1, the molar ratio of the thiol compound with hydrogen atoms attached to both ends of the R2 substituent to epichlorohydrin is 1:2-10; and the molar ratio of the epoxy group compound to NH4SCN in the cyclosulfidation reaction is 1:2-8.

[0018] Preferably, the reaction temperature for forming the epoxy group compound in step 1 is -120°C, and the cyclosulfidation reaction temperature is room temperature.

[0019] Preferably, the molar ratio of the cyclic sulfide compound to sodium hydrosulfide and hydrogen sulfide in step 2 is 1:1.5-3:2-5.

[0020] Preferably, the reaction temperature in step 2 is 0-5℃.

[0021] Preferably, in step 3, the molar ratio of the product from step 2 to dihydroxydithiane is 1:compound 1-2.

[0022] Preferably, the reaction temperature in step 3 is from room temperature to reflux heating.

[0023] Preferably, in step 4, the molar ratio of the product of step 3 to (meth)acrylic anhydride is 1:2-3, the base is triethylamine or 4-(N,N-dimethylamino)pyridine, and the molar ratio of the product of step 3 to the base is 1:2-5.

[0024] Preferably, the reaction temperature in step 4 is 15-100℃.

[0025] The specific structure of the present invention is illustrated below:

[0026]

[0027] The beneficial effects of this invention are that it designs a series of high-sulfur, high-refractive-index monomer structures. The refractive index properties of these compounds are all characterized using an Abbe refractometer, with values ​​all above 1.668, making them suitable for the fabrication of high-refractive-index devices. They possess a wide spectral range, high chemical stability, and good adjustability. This gives them broad application potential in various fields such as high-refractive-index lenses, optical fibers and other optical components, ultraviolet, visible, and near-infrared optical devices, optical communication systems such as lasers and fiber optic sensors, chemical and biological sensors, photoresists, and coatings. This series of high-refractive-index structures has not yet been reported in the literature. Furthermore, the synthetic route of this invention is universal, using dithiocyclopentane as the linking unit, combined with a series of structural units with high molar refractive indices and photocurable groups. This improves the refractive index of the material while ensuring the monomer remains liquid, allowing for easy dissolution, complete solid content, and no pollution during polymerization. The structure contains rigid, large conjugated aromatic rings and high-sulfur-content dithiocyclopentane methanethiol, which reduces material dispersion while imparting certain physical properties. Detailed Implementation

[0028] The present invention is illustrated below with reference to examples, but is not intended to limit the invention. Any simple substitutions or modifications made to the present invention by those skilled in the art are within the scope of the technical solutions protected by this invention.

[0029] Example 1: Preparation of Compound 1

[0030] The reaction formula for preparing compound 1 is as follows:

[0031]

[0032] The synthesis process of compound 1-ii is as follows:

[0033] In a four-necked flask equipped with a stirrer, thermometer, constant-pressure dropping funnel, serpentine condenser, and nitrogen protection device, compound 1-i (100 g, 0.357 mol) and tetramethylammonium bromide (11 g, 0.071 mol) were dissolved in compound 1-ii (330.3 g, 3.57 mol). After purging with nitrogen for 30 min at room temperature, the mixture was stirred at room temperature for 3 h. Then, a mixed solution of sodium hydroxide (28.56 g, 0.714 mol) and ethanol (30 g) was slowly added dropwise at a rate of 0.5 drops / second. The reaction was continued at this temperature for 2 h until completion. Excess compound 1-ii and solvent were removed by vacuum distillation, followed by washing with deionized water, extraction, and recrystallization to obtain compound 1-iii (125.95 g, yield: 90%, HPLC purity: 96%).

[0034] The synthetic route for compound 1-v is as follows:

[0035] In a three-necked flask equipped with a stirrer, thermometer, and nitrogen protection, compound 1-iii (125 g, 0.319 mol) and NH4SCN (145.6 g, 1.91 mol) were dissolved in a mixture of acetone (1 L) and tetrahydrofuran (1 L). The reaction was carried out at room temperature for 12 hours under nitrogen protection until the reaction was complete. The solvent was removed by vacuum distillation of the reaction solution, the reaction was quenched with 300 mL of water, and then extracted with dichloromethane (3 × 200 mL). The combined organic phases were washed twice with deionized water, dried over anhydrous sodium sulfate, and finally purified by column chromatography with petroleum ether:acetone = 1:4 to give a white powder compound 1-v (112.17 g, yield: 82.8%, HPLC purity: 97%).

[0036] The synthetic route for compound 1-vi is as follows:

[0037] Sodium hydrosulfide (22.2 g, 0.396 mol) was dissolved in methanol (100 mL) in a three-necked flask equipped with a stirrer, thermometer, and nitrogen protection, and cooled to 0 °C. Hydrogen sulfide gas was then slowly bubbled into the solution for 5 minutes. Over 10 minutes, a chloroform / methanol solution (112 g, 0.264 mol, v / v) was added to the solution while hydrogen sulfide gas was continuously bubbled in. The mixture was stirred at 0 °C for another 30 minutes, then at room temperature for 2 hours, until the starting material disappeared according to TLC. The reaction mixture was poured into water (2 L), acidified to pH 3-5 with a small amount of sulfuric acid (1 M), extracted with ethyl acetate (3 × 200 mL), and the combined organic phases were washed once with saturated brine, dried over anhydrous sodium sulfate, and concentrated to give a white solid, compound 1-vi (127.5 g, yield 98%, HPLC: 99%).

[0038] Synthetic route of compound 1-viii:

[0039] In a three-necked flask equipped with a stirrer, thermometer, water separator, and reflux tube, compounds 1-vi (127.5 g, 0.259 mol), 1-vii (39.4 g, 0.259 mol), and TsOH (0.00313 mol, 0.54 g) were dissolved in benzene (480 mL). The mixture was refluxed and stirred for 24 hours, and TLC showed that the starting material disappeared. After cooling the reaction solution, the organic phase was washed once with saturated NaHCO3 aqueous solution, dried over anhydrous sodium sulfate, and concentrated. Finally, the target product, compound 1-viii (154.6 g, yield: 98%, HPLC purity: 97%), was purified by column chromatography.

[0040] Synthetic route of compound 1-:

[0041] In a three-necked flask equipped with a stirrer, compounds 1-viii (154 g, 0.253 mol) and 1-ix (82 mL, 0.506 mol) were dissolved in dichloromethane (300 mL). Et3N (77.4 mL, 0.56 mol) and 4-(N,N-dimethylamino)pyridine (0.185 g, 0.0015 mol) were slowly added under ice bath conditions. The mixture was stirred at room temperature for 12 hours, and TLC showed the disappearance of the starting material. The reaction solution was diluted with dichloromethane (500 mL), and the combined organic phases were washed twice with saturated saline solution. The organic layer was dried over anhydrous sodium sulfate and concentrated. Column chromatography was performed using n-hexane:ethyl acetate (7:1) eluent to obtain the oily target product 1 (158.36 g, yield: 84%, HPLC purity: 98%).

[0042] The chemical structure of compound 1 was tested, and its refractive index was measured to be 1.653. The NMR characterization results are as follows:

[0043] 1 HNMR (400MHz, DMSO) δ: 7.08 (d, 2H), 6.09 (dt, 4H), 6.27-6.13 (t, 4H), 3.69-3.44 (m, 6H), 3.23-2.62 (m, 10H), 2.34 (s, 6H).

[0044] Example 2 Preparation of Compound 2

[0045] The preparation method in this embodiment is similar to that in Example 1, except that the acrylic anhydride in step 4 is replaced by... The structural formula of compound 2 is obtained as follows:

[0046]

[0047] The chemical structure of compound 2 was tested, and its refractive index was measured to be 1.675. The NMR characterization results are as follows:

[0048] 1 HNMR(400MHz,DMSO)δ:7.10(d,2H), 6.92-6.09(dt,4H), 6.35-6.15(m,6H),

[0049] 3.77-3.44(m,6H),3.23-3.11(m,6H),2.88-2.62(m,4H).

[0050] Example 3 Preparation of Compound 3

[0051] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Acrylic anhydride is substituted with raw material The structural formula of compound 3 is obtained as follows:

[0052]

[0053] The chemical structure of compound 3 was tested, and its refractive index was measured to be 1.673. The NMR characterization results are as follows:

[0054] 1 HNMR(400MHz, DMSO)δ:7.28-7.16(d,8H),6.27-6.13(m,4H),3.77-3.44(m,6H),3.09-2.96(m,6H),2.88-2.62(m,4H),2.34(s,6H).

[0055] Example 4: Preparation of Compound 4

[0056] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Acrylic anhydride is substituted with raw material The structural formula of compound 4 was obtained as follows:

[0057]

[0058] The chemical structure of compound 4 was tested, and its refractive index was measured to be 1.676. The NMR characterization results are as follows:

[0059] 1 ¹H NMR (400 MHz, DMSO) δ: 7.28–7.16 (d, 8H), 6.37–6.19 (m, 6H), 3.8 compound 1–3.49 (m, 6H), 3.1 compound 1–2.98 (m, 6H), 2.86–2.59 (m, 4H).

[0060] Example 5: Preparation of Compound 5

[0061] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Methacrylic anhydride raw material is The structural formula of compound 5 was obtained as follows:

[0062]

[0063] The chemical structure of compound 5 was tested, and its refractive index was measured to be 1.669. The NMR characterization results are as follows:

[0064] 1HNMR(400MHz,DMSO)δ:6.27(t,2H),6.13(t,2H),3.76-3.42(m,6H),3.37-3.11(m,6H),3.33(s,4H),2.87-2.64(m,4H),2.36(s,6H).

[0065] Example 6 Preparation of Compound 6

[0066] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Methacrylic anhydride raw material is The structural formula of compound 6 is obtained as follows:

[0067]

[0068] The chemical structure of compound 6 was tested, and its refractive index was measured to be 1.672. The NMR characterization results are as follows:

[0069] 1 HNMR (400MHz, DMSO) δ: 6.35-6.19(m,6H), 3.76-3.43(m,6H), 3.37-3.11(m,6H), 3.32(s,4H), 2.88-2.62(m,4H).

[0070] Example 7 Preparation of Compound 7

[0071] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Methacrylic anhydride raw material is The structural formula of compound 7 was obtained as follows:

[0072]

[0073] The chemical structure of compound 7 was tested, and its refractive index was measured to be 1.676. The NMR characterization results are as follows:

[0074] 1 HNMR(400MHz,DMSO)δ:7.90(dd,2H),7.55(dd,2H),7.38-7.27(m,8H),7.08-7.01(m,4H), 6.27-6.13(dt,4H),3.76-3.45(m,6H),3.23-2.97(m,6H),2.89-2.63(m,4H),2.33(s,6H).

[0075] Example 8: Preparation of Compound 8

[0076] The preparation method in this embodiment is similar to that in Example 1, except that the raw material in step 1 is... Step 4: Methacrylic anhydride raw material is The structural formula of compound 8 is obtained as follows:

[0077]

[0078] The chemical structure of compound 8 was tested, and its refractive index was measured to be 1.679. The NMR characterization results are as follows:

[0079] 1 HNMR(400MHz,DMSO)δ:7.89(dd,2H),7.54(dd,2H),7.37-7.26(m,8H),7.08(d,4 H),6.35-6.15(m,6H),3.77-3.44(m,6H),3.22-2.98(m,6H),2.88-2.62(m,4H).

[0080] The refractive indices of the aforementioned compounds are all above 1.668, making them suitable for the fabrication of high-refractive-index devices. Their wide spectral range, high chemical stability, and good tunability give them broad application potential in various fields, including high-refractive-index lenses, optical fibers and other optical components, ultraviolet, visible, and near-infrared optical devices, optical communication systems such as lasers and fiber optic sensors, chemical and biological sensors, photoresists, and coatings.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A photopolymerizable refractive monomer, characterized in that, The structural formula is as follows: ， wherein, R1 is selected from -H, -CH3, R2is selected from , , , .

2. The method for preparing the refractive monomer as described in claim 1, characterized in that, The method comprises the following steps: (1) reacting a HS-R2-SH thiol compound with epichlorohydrin to form an epoxy group compound (1), and then reacting with NH4SCN to perform a ring sulfurization reaction to obtain a ring sulfur group compound (2); (2) reacting the ring sulfur group compound (2) with sodium hydrosulfide and hydrogen sulfide to obtain two dithiol group compounds (3); (3) reacting the product of step 2 with 2,5-dihydroxy-1,4-dithiane to obtain a dithiolane methylthiol group compound (4); (4) substituting the product of step 3 with 2-methyl acrylate or acrylate under the catalysis of a base to prepare the refractive monomer; The reaction formula is as follows: 。 3. The production method according to claim 2, wherein The molar ratio of the HS-R2-SH thiol compound to epichlorohydrin in step 1 is 1:2-10; and the molar ratio of the epoxy group compound (1) to NH4SCN in the ring sulfurization reaction is 1:2-8.

4. The production method according to claim 2, wherein The reaction temperature for forming the epoxy group compound (1) in step 1 is -120°C, and the ring sulfurization reaction temperature is room temperature.

5. The production method according to claim 2, wherein The molar ratio of the ring sulfur group compound (2) to sodium hydrosulfide and hydrogen sulfide in step 2 is 1:1.5-3:2-5.

6. The production method according to claim 2, wherein The reaction temperature in step 2 is 0-5°C.

7. The production method according to claim 2, wherein The molar ratio of the product of step 2 to 2,5-dihydroxy-1,4-dithiane in step 3 is 1:1-2.

8. The production method according to claim 2, wherein The reaction temperature in step 3 is room temperature to reflux heating.

9. The production method according to claim 2, wherein The molar ratio of the product of step 3 to 2-methyl acrylate or acrylate in step 4 is 1:2-3, the base is triethylamine or 4-(N,N-dimethylamino)pyridine, and the molar ratio of the product of step 3 to the base is 1:2-5.

10. The production method according to claim 2, wherein The reaction temperature in step 4 is 15-100°C.

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