Selenium thio-raft agent, its synthesis method and application
By synthesizing selenium-thio-RAFT reagents, the limitations of existing RAFT reagents in application have been solved, and efficient and controllable polymerization of acrylates and styrene monomers has been achieved. The polymerization process is mild, and the molecular weight and functional groups of the products are controllable.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CNOOC CHANGZHOU PAINT & COATINGS IND RES INST
- Filing Date
- 2023-12-23
- Publication Date
- 2026-06-30
AI Technical Summary
The application scope of existing RAFT reagents is limited, restricting their selectivity and applicability in the polymerization process, especially in the polymerization of vinyl monomers with special functional groups. Furthermore, traditional RAFT reagents have relatively strict requirements for polymerization conditions.
A selenium-thioRAFT reagent was synthesized by reacting selenium powder, sodium borohydride, liquid carbon disulfide, and methyl 2-bromopropionate under an inert gas atmosphere to prepare a novel chain transfer reagent for controlled free radical polymerization.
It achieves efficient and controllable polymerization of acrylate and styrene monomers, with a mild polymerization process, light color of RAFT reagent in the polymerization product, and controllable molecular weight and functional groups.
Smart Images
Figure CN117820183B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer synthesis technology, specifically relating to a selenium-thio-RAFT reagent, its synthesis method, and its application. Background Technology
[0002] Living radical polymerization (LRP) combines the advantages of living polymerization and free radical polymerization, making it one of the hottest topics in polymer synthesis research today. To date, several relatively mature LRP methods have been reported, among which the RAFT polymerization system possesses a series of advantages: high control over the polymerization process, powerful molecular structure design capabilities, a wide range of applicable monomer faces, applicability to LRP of vinyl monomers with special functional groups, controllable free radical polymerization in heterogeneous systems, and mild polymerization conditions, demonstrating strong potential for industrial applications.
[0003] However, the scope of RAFT reagents has been limited to dithiocarbonyl compounds, such as dithioesters, dithiocarbamates, xanthates, trithioesters, and phosphate dithioesters, and they exhibit strong selectivity for monomers, which greatly restricts the application of RAFT polymerization. Therefore, the synthesis of novel RAFT reagents is of practical significance for the application of RAFT polymerization. Organoselenium compounds and organoselenium polymers have rich and unique physiological and medical effects and functional applications; therefore, introducing selenium atoms and selenium functional groups into polymers has become one of the hot topics in polymer research. Referring to the TEP polymerization method, the monomer applicability of tellurium ethers is broader than that of sulfides used in RAFT polymerization. Selenium, situated between sulfur and tellurium, has the potential to be developed into another class of highly efficient LRP regulators. Summary of the Invention
[0004] This invention is proposed to overcome the shortcomings of the limited application scope of RAFT reagents in the prior art. Its purpose is to provide a selenium-thiolated RAFT reagent and its synthesis method and application.
[0005] This invention is achieved through the following technical solution:
[0006] A method for synthesizing a selenium-thioRAFT reagent includes the following steps:
[0007] (i) Sodium borohydride was dissolved in deionized water to obtain sodium borohydride solution. The sodium borohydride solution was added dropwise to the suspension obtained by mixing selenium powder and deionized water under the protection of ice water bath at 0℃ and argon gas. After the addition was completed, the reaction was continued for 1 hour. The reaction system was a gray solution, and intermediate product A was obtained.
[0008] (ii) Add an alkaline substance (sodium hydroxide) to the reaction system (gray solution) after the reaction in step (i). Continue the reaction for 30 minutes after the addition is complete. The reaction system turns dark purple to obtain intermediate product B.
[0009] (iii) Mix liquid carbon disulfide and liquid tetrahydrofuran, and add the mixture dropwise to the reaction system (deep purple solution) of step (ii) at 0°C. After reacting for 3 hours, the intermediate product C is obtained.
[0010] (iv) Weigh methyl 2-bromopropionate and add it dropwise to the reaction system (deep purple solution) containing intermediate product C at 0℃. After the addition is complete, continue the reaction for 3 hours.
[0011] (v) Extract the solution after the reaction in step (iv) with n-hexane (3 × 150 mL), remove the solvent from the extract under reduced pressure to obtain a red oily substance, and purify it by column chromatography (using n-hexane as the eluent) to obtain the final red oily product, which is the selenothio-RAFT reagent OSC.
[0012] In the above technical solution, the synthesis method is carried out under the protection of an inert gas; the inert gas is any one of argon, nitrogen, helium or neon, preferably argon.
[0013] In the above technical solution, the reduction process of selenium powder and sodium borohydride is relatively violent and requires strict temperature control. The sodium borohydride solution is added dropwise under the protection of a 0°C ice-water bath and argon gas, and the temperature of the mixed solution is controlled at 0°C during the dropwise addition process.
[0014] In the above technical solution, the sodium borohydride solution is obtained by dissolving sodium borohydride in deionized water, and the concentration of the sodium borohydride solution is 2 mol / L to 3 mol / L; the selenium powder suspension is formed by mixing selenium powder and deionized water, and the concentration of the selenium powder suspension is 1 mol / L to 1.5 mol / L; the molar ratio of selenium powder to sodium borohydride is 1:2.
[0015] In the above technical solution, the alkaline substance is sodium hydroxide, and the molar ratio of the alkaline substance to selenium powder is 1:1.
[0016] In the above technical solution, the volume ratio of carbon disulfide to tetrahydrofuran is 1:10.
[0017] In the above technical solution, the molar ratio of selenium powder to methyl 2-bromopropionate is 1:2.
[0018] In the above technical solution, selenool (intermediate product C) in the reaction is prone to coupling to generate a small amount of diselenoether product under alkaline conditions. Its polarity is similar to that of the product, making column chromatography purification difficult. It is easier to obtain the target product by performing column chromatography when the reaction conversion rate of the substance to be purified is high and the flow rate is low. Specifically, the mixture after the reaction contains OSC and other reaction byproducts. When the OSC content is high, the reaction is terminated and column chromatography is performed for separation. The flow rate of the column press is controlled at 10 mL / min to 15 mL / min.
[0019] A selenium-thio RAFT reagent, wherein the selenium-thio RAFT reagent has the following structural formula:
[0020]
[0021] In the formula: the structural formulas of R1 and R2 are both C n H 2n+1 n is 1 to 4.
[0022] The application of a selenium-thio RAFT reagent in free radical polymerization, wherein the selenium-thio RAFT reagent acts as a chain transfer agent, enabling the free radical polymerization process to be controlled through reversible addition-fragmentation chain transfer.
[0023] In the above technical solution, the free radical polymerization includes acrylate monomer polymerization or styrene monomer polymerization.
[0024] In the above technical solution, the reaction temperature for the polymerization of acrylate monomers or styrene monomers is 50℃~80℃, preferably 60℃; the reaction time is 1h~24h, preferably 2h.
[0025] In the above technical solution, the molar ratio of monomer, RAFT reagent, and initiator in the polymerization reaction of acrylate monomers or styrene monomers is 100:1:0.5.
[0026] In the above technical solution, the polymerization of acrylate monomers or styrene monomers is carried out under anaerobic conditions in a solvent; the solvent is preferably toluene.
[0027] In the above technical solution, the polymerization reaction of acrylate monomers or styrene monomers is carried out under the protection of an inert gas. The inert gas can be any one of argon, nitrogen, helium, and neon, with argon being preferred for atmosphere protection.
[0028] In the above technical solution, methyl acrylate (MA) and styrene (St) are used as polymerization monomers. Before use, they need to be removed by alkaline alumina column to remove residual polymerization inhibitors from the monomers. After treatment, they are sealed and stored at 0℃~3℃.
[0029] The beneficial effects of this invention are:
[0030] This invention provides a novel selenium thio compound as a highly efficient RAFT reagent. The RAFT reagent, as a chain transfer agent, is applied to the free radical polymerization of highly reactive acrylate monomers and less reactive styrene monomers, exhibiting living polymerization characteristics and good polymerization controllability. In the organic synthesis of the RAFT reagent, selenides are used as regulators to synthesize organoselenium polymers with predetermined molecular weight, selenium content, and functional groups. The RAFT reagent has a light color, and the final polymer product is essentially free of RAFT reagent color. Attached Figure Description
[0031] Figure 1 The 1H NMR spectrum of the selenium-thioRAFT reagent prepared in Example 1 of this invention;
[0032] Figure 2 The carbon NMR spectrum of the selenium-thioRAFT reagent prepared in Example 1 of this invention;
[0033] Figure 3 The infrared spectrum of the selenium-thioRAFT reagent prepared in Example 1 of this invention;
[0034] Figure 4 The mass spectrum of the selenium-thioRAFT reagent prepared in Example 1 of this invention;
[0035] Figure 5 The above is the 1H NMR spectrum of the acrylate polymerization kinetics monitoring in Example 2 of this invention;
[0036] Figure 6 The kinetic curve of acrylate in Example 2 of this invention (squares represent ln([M]0 / [M])-time, and dots represent conversion-time);
[0037] Figure 7 This is the 1H NMR spectrum of styrene polymerization kinetics monitoring in Example 3 of the present invention;
[0038] Figure 8 The styrene kinetic curve in Example 3 of this invention (squares represent ln([M]0 / [M])-time, and dots represent conversion rate-time);
[0039] Figure 9 The images show the 1H NMR spectrum and GPC elution curve of the polymerized products of acrylate from Example 2 and styrene from Example 3 of this invention.
[0040] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation
[0041] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.
[0042] The testing instruments and conditions in this embodiment of the invention are as follows:
[0043] Fourier Transform Infrared Spectroscopy (FT-IR): The structure of the RAFT reagent was characterized using a BRUKER TENSOR 27 Fourier Transform Infrared Spectrometer.
[0044] 1H NMR spectrum 1 H-NMR: Measured at room temperature using a Bruker 300MHz NMR spectrometer with CDCl3 or DMSO-d6 as solvent and TMS as internal standard.
[0045] Gel permeation chromatography (GPC): Molecular weight and molecular weight distribution were determined using a gel permeation chromatograph equipped with TOSOH TSKgel SuperHM-M, an automated injection system. Polymethyl methacrylate or polystyrene was used as a standard to calculate the polymer molecular weight. N,N-dimethylformamide (DMF) was used as the mobile phase at a flow rate of 0.65 mL / min and a temperature of 40 °C.
[0046] Example 1
[0047] A method for preparing a selenothio-RAFT reagent {2-((((1-methoxy-1-oxopropane-2-yl)selenoyl)thiocarbonyl)methyl thiopropionate} (OSC) is as follows:
[0048] Sodium borohydride (7.60 g, 0.2 mol) was dissolved in 75 mL of deionized water and added dropwise to a mixture of selenium powder (7.8 g, 0.1 mol) and 75 mL of deionized water under an ice bath and Ar atmosphere at 0 °C. The reaction was allowed to proceed for 1 h until the system turned gray, yielding intermediate A. Subsequently, sodium hydroxide (4.0 g, 0.1 mol) was added to the system, and the reaction was allowed to proceed for 30 min until the system turned deep purple, yielding intermediate B. Carbon disulfide solution (15 mL) was mixed with 150 mL of tetrahydrofuran solution and added dropwise to the reaction system at 0 °C. After reacting for 3 h, intermediate C was obtained. Finally, methyl 2-bromopropionate (33.4 g, 0.2 mol) was added dropwise to the reaction system containing intermediate C at 0 °C, and the reaction was allowed to continue for 3 h. The final reaction mixture was extracted with n-hexane (3 × 150 mL). The solvent in the extract was removed under reduced pressure to obtain a red oily substance, which was purified by column chromatography (using n-hexane as the eluent) to obtain the final red oily product, which is the selenothio-RAFT reagent OSC, with a product yield of 51%.
[0049] The selenium-thioRAFT reagent prepared in Example 1 was subjected to NMR and IR detection respectively:
[0050] from Figure 1 As can be seen from the 1H NMR spectrum, the integrated peaks in the 1H NMR spectrum can be correctly identified and assigned to their respective peaks. 1 H NMR (300MHz, CDCl3, δ): 3.61 (s, 6H), 3.6-3.8 (m, 2H), 1.62 (m, 3H), 1.43 (m, 3H).
[0051] from Figure 2 As can be seen from the carbon NMR spectrum, each peak can be assigned to its corresponding position. 13 C NMR (75MHz, CDCl3, δ): 172-170 (C=O), 51.82 (OCH3), 50.11 (CS) 34.17 (C-Se) ppm.
[0052] from Figure 3 The infrared spectrum shows that the infrared spectrum at 1060 cm⁻¹... -1 A stretching vibration peak of the C=S bond appears at 1210 cm⁻¹. -1 With 1750cm -1 The peaks of stretching vibrations of the CS bond and the C=O bond, as well as the peak at 2980 cm⁻¹, are observed. -1 An alkyl CH stretching vibration peak appeared nearby.
[0053] from Figure 4 The mass spectrum shows that the LCMS(ESI) m / z is [M+1]. + calcd.for C9H 14 S2Se,329.2945,found:331.0903.
[0054] Example 2
[0055] The application of a selenium-thio-RAFT reagent in the living radical polymerization of acrylates is as follows:
[0056] The monomer methyl acrylate (MA) (861.0 mg, 10.0 mmol), the selenothio-RAFT reagent OSC prepared in Example 1 (16.5 mg, 0.05 mmol), the initiator azobisisobutyronitrile (AIBN) (1.64 mg, 0.01 mmol), and 450 μL of solvent toluene were mixed and polymerized under anaerobic conditions at 60 °C (using a double-row tube for three cycles of freezing-evacuation-gas filling-thawing to remove oxygen, argon gas). Samples were taken at different time intervals under anaerobic conditions. The reaction progress was monitored, and the conversion rate was calculated by NMR characterization.
[0057] from Figure 5The 1H NMR spectrum of the acrylate polymerization kinetics monitoring shows that the conversion rate can reach 95% in four hours.
[0058] from Figure 6 The kinetic curves of acrylate polymerization show that there is a 20-minute induction period, and ln([M]0 / [M]) has a first-order kinetic relationship with time, indicating that the polymerization has the characteristics of living polymerization.
[0059] Example 3
[0060] The application of a selenium-thio-RAFT reagent in the living radical polymerization of styrene is as follows:
[0061] The monomer styrene St (1041.8 mg, 10.0 mmol), the selenothio-RAFT reagent OSC prepared in Example 1 (16.5 mg, 0.05 mmol), the initiator azobisisobutyronitrile (AIBN) (1.64 mg, 0.01 mmol), and 550 μL of solvent toluene were mixed and polymerized under anaerobic conditions at 60 °C (three cycles of freezing-evacuation-gas filling-thawing were performed in a double-row tube to remove oxygen, using argon gas). Samples were taken at different intervals under anaerobic conditions to monitor the reaction progress, and the conversion rate was calculated by NMR characterization.
[0062] from Figure 7 The 1H NMR spectrum of styrene polymerization kinetics shows that the polymerization rate of low-activity styrene monomers is relatively slow, but a conversion rate of 53% can still be achieved in about 48 hours.
[0063] from Figure 8 The polymerization kinetics curve of styrene shows that there is also an induction period in the polymerization, and ln([M]0 / [M]) has a first-order kinetic relationship with time, indicating that the polymerization has the characteristics of living polymerization.
[0064] from Figure 9 The 1H NMR spectrum and GPC elution curve of the final polymer of acrylate and styrene showed that the molecular weight distribution of the final polymer was narrow, which is consistent with the characteristics of living polymerization.
[0065] As can be seen from Examples 2 and 3, the polymerization reaction can be carried out in a solvent using only the selenium thio compound synthesized in this invention as a chain transfer agent and commonly used methyl acrylate or styrene as monomers, without the need for other substances. The reaction is mild and the polymerization is controllable.
[0066] Free radical polymerization using selenium-thioRAFT reagent must be carried out under anaerobic conditions. The polymerization is performed using Schlenk tubes, and the reaction system is deoxygenated three times using a double-row tube cycle of freezing-evacuation-gas filling-thawing to ensure that the polymerization is carried out under anaerobic conditions. When taking samples during the process, the oxygen in the needle must be completely purged under an argon flow before taking the sample.
[0067] The synthesis principle of this invention:
[0068] The RAFT reagent of this invention is a novel selenium-sulfur chain transfer reagent prepared by organic synthesis in the presence of selenium powder, sodium borohydride, carbon disulfide and methyl 2-bromopropionate.
[0069] Selenium powder undergoes a reduction reaction to generate compound A (sodium selenide). Compound A then reacts under alkaline conditions to generate compound B (sodium selenide anion). Compound B further reacts at low temperature to generate compound C (sodium dithiocarbonate). Finally, it reacts with a substitution reaction to generate the selenothioRAFT reagent OSC. The synthetic route is as follows:
[0070]
[0071] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.
[0072] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.
Claims
1. A method of synthesis of a selenium thio-RAFT agent, characterized in that: Includes the following steps: (i) Sodium borohydride solution was added dropwise to the selenium powder suspension. After the addition was complete, the reaction continued. After the reaction was complete, intermediate product A was obtained. (ii) Add an alkaline substance to the solution after the reaction in step (i) is completed. After the addition is complete, continue the reaction. After the reaction is complete, intermediate product B is obtained. (iii) After mixing carbon disulfide and tetrahydrofuran, add them dropwise to the solution after the reaction in step (ii) is completed. Continue the reaction after the addition is complete. After the reaction is complete, the intermediate product C is obtained. (iv) Add methyl 2-bromopropionate dropwise to the solution from step (iii) after the reaction is complete, and continue the reaction after the addition is complete; (v) The solution obtained after the reaction in step (iv) is extracted, distilled under reduced pressure, and purified by column chromatography to obtain the final red oily product, which is the selenothio-RAFT reagent. The synthesis route is as follows: 。 2. The method of synthesis of seleno-thio-RAFT agents according to claim 1, characterized in that: The synthesis method is carried out under the protection of an inert gas; the inert gas is any one of argon, nitrogen, helium or neon; the reaction time after the addition of step (i) is 1 h; the reaction time after the addition of step (ii) is 30 min; the reaction time after the addition of steps (iii) and (iv) is 3 h.
3. The method for synthesizing the selenothio-RAFT reagent according to claim 1, characterized in that: The sodium borohydride solution is obtained by dissolving sodium borohydride in deionized water, and the concentration of the sodium borohydride solution is 2 mol / L to 3 mol / L; the selenium powder suspension is formed by mixing selenium powder and deionized water, and the concentration of the selenium powder suspension is 1 mol / L to 1.5 mol / L; the molar ratio of selenium powder to sodium borohydride is 1:
2.
4. The method for synthesizing the selenothio-RAFT reagent according to claim 1, characterized in that: The sodium borohydride solution was added dropwise under the protection of an ice-water bath at 0°C and argon gas, and the temperature of the mixed solution was controlled at 0°C during the dropwise addition process.
5. The method for synthesizing the selenothio-RAFT reagent according to claim 1, characterized in that: The alkaline substance is sodium hydroxide, and the molar ratio of the alkaline substance to selenium powder is 1:
1.
6. The method for synthesizing the selenothio-RAFT reagent according to claim 1, characterized in that: The volume ratio of carbon disulfide to tetrahydrofuran is 1:
10.
7. The method for synthesizing the selenothio-RAFT reagent according to claim 1, characterized in that: The molar ratio of selenium powder to methyl 2-bromopropionate is 1:
2.
8. A selenium-thioRAFT reagent synthesized by the method according to any one of claims 1 to 7, characterized in that: The selenium-thioRAFT reagent has the following structural formula: 。 9. The application of a selenium-thioRAFT reagent synthesized by the method according to any one of claims 1 to 7 in free radical polymerization, characterized in that: The selenium-thio-RAFT reagent, as a chain transfer agent, enables the free radical polymerization process to be controlled through reversible addition-fragmentation chain transfer.
10. The application of the selenium-thioRAFT reagent according to claim 9 in free radical polymerization, characterized in that: The polymerization reaction temperature used is 50℃~80℃; the polymerization reaction time is 1h~24h.