Functionalized modified cellulose loaded Salen TiIV catalyst as well as preparation method and application thereof
By preparing functionalized modified cellulose-loaded Salen TiIV catalyst, the environmental pollution and high cost problems of metal-based catalysts in the catalytic field are solved, and a reusable, low-cost, and efficient catalyst is provided for the asymmetric oxidation reaction of sulfides, achieving stable catalytic performance and wide substrate applicability.
Patent Information
- Application Number
- CN202510891043.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-30
- Publication Date
- 2025-09-23
AI Technical Summary
Existing metal-based catalysts in the catalytic field have problems such as difficulty in recycling, easy catalyst residue causing environmental pollution, high production cost, and unstable binding between catalyst and substrate. There is also a lack of solutions for the application of simple, easy-to-operate, low-cost, and environmentally friendly catalysts in the asymmetric oxidation reaction of sulfides.
A preparation method for a functionalized modified cellulose-supported Salen TiIV catalyst is adopted, in which components such as (R,R)-cyclohexanediamine, 3,5-di-tert-butyl salicylaldehyde, 3-tert-butyl-5-chloromethyl salicylaldehyde and titanium tetraisopropoxide are reacted to form a chloromethyl chiral Salen TiIV catalyst, which is then combined with nano-microcrystalline cellulose to form a functionalized modified cellulose-supported Salen TiIV catalyst.
The catalyst is reusable, environmentally friendly, and low-cost, and exhibits high catalytic performance and selectivity in the asymmetric oxidation reaction of sulfides. It is applicable to a wide range of substrates and has good stability and catalytic activity.
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Figure CN120682272A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalyst preparation, and in particular to a functional modified cellulose loaded Salen Ti IV Catalyst, preparation method and application thereof. Background Art
[0002] Metal-based catalysts have become the mainstream catalysts in the catalytic field, but they face challenges such as difficulty in recycling, environmental pollution caused by catalyst carryover, high production costs, and unstable catalyst-substrate binding. Currently, cellulose polymers are commonly used as carriers and coordinated with salen ligands to address these issues.
[0003] Cellulose is the most abundant natural, environmentally friendly polymer on Earth and a renewable material. As a catalyst carrier, it boasts excellent properties such as widespread availability, biodegradability, and non-toxicity. Furthermore, the abundant hydroxyl groups in its molecular structure make it easily functionalizable and can be effectively loaded with metal ions through a variety of methods.
[0004] Examples of the application of cellulose loaded with metal ions in the prior art are as follows: In 2016, Xinyun Wu et al. HYPERLINK "https: / / www.x-mol.com / paper / journal / 143?r_detail= 1235484544903921664&readMode=zh"ACS SustainableChemistry&Engineering reported a HYPERLINK "https: / / www.x-mol.com / paperRedirect / 1235484544903921664" \t"_blank" synthesis strategy of porous cellulose nanocrystals loaded with metal nanocatalysts; in 2019, Zheng-Tian Xie et al. HYPERLINK "https: / / www.x-mol.com / paper / journal / 449?r_detail=5601294& readMode=zh"CarbohydratePolymers reported a high catalytic efficiency green flow reactor based on HYPERLINK "https: / / www.x-mol.com / paperRedirect / 5601294" \t "_blank" monolithic cellulose-loaded metal nanoparticles; in 2021, Samir Kamel et al. HYPERLINK "https: / / www.x-mol.com / paper / journal / 1325?r_detail=1375495324738994176&readMode=zh"Cellulose A method for green and sustainable catalytic organic synthesis using cellulose-loaded metal nanoparticles was reported.
[0005] Salen ligands, prepared from primary diamines and salicylaldehydes, are commonly used chelating ligands in coordination chemistry due to their ease of synthesis, recyclability, strong coordination capacity, and wide applicability. The ability of metal ions to form stable complexes with these ligands, combined with their unique molecular magnetic properties, pharmacological activity, and optical properties, holds broad application prospects in biomedicine, catalytic materials, and sensors.
[0006] Examples of the application of metal-Salen complexes are as follows: In 2011, Rosalind A Rosenthal et al. HYPERLINK "https: / / www.x-mol.com / paper / journal / 5572?r_detail= 1213057545966653440"Anti-Cancer Agents in Medicinal Chemistry reported that Salen Mn complexes can be used to reduce delayed radiation damage to normal tissues after radiotherapy, accidental exposure or radioterrorism; in 2017, Yaoyao Zhang et al. Green Chemistry A chiral Salen Ti IV The biomimetic single-chain polymer nanoparticles of the complex achieve highly enantioselective sulfoxidation in water; in 2019, Giuseppe Consiglio et al. Molecules A kind of Salen Zn II HYPERLINK "https: / / www.x-mol.com / paperRedirect / 5762280" \t "_blank" Application of Schiff base complexes as Lewis base colorimetric and fluorescent chemosensors in cell imaging.
[0007] Chiral sulfoxides are an important class of fine chemical intermediates, widely used in the synthesis of pharmaceutical intermediates. IV Complex-catalyzed asymmetric oxidation of thioethers is one of the most direct and effective routes to obtain chiral sulfoxides.
[0008] In summary, it is feasible and urgent to provide a simple, easy-to-operate, low-cost, environmentally friendly, and reusable catalyst for the asymmetric oxidation reaction of sulfides. Summary of the Invention
[0009] The purpose of the present invention is to overcome the above problems existing in the prior art and provide a functional modified cellulose loaded Salen Ti IV Catalyst and its preparation method and application, the functionalized modified cellulose loaded Salen Ti IV The catalyst used in the asymmetric oxidation reaction of sulfides not only has high catalytic performance, but also has the characteristics of low cost, environmental friendliness and excellent reusability.
[0010] In order to achieve the above object, the present invention provides a functional modified cellulose loaded Salen Ti IV The preparation method of the catalyst comprises the following steps: S1, mixing (R,R)-cyclohexanediamine, ethereal hydrochloric acid solution, and a first organic solvent, and stirring to obtain a mixture, mixing the mixture, 3,5-di-tert-butyl salicylaldehyde, and a mixed solution of MeOH-EtOH, and then reacting to obtain a reaction mass; S2. Mixing the reaction material obtained in step S1, 3-tert-butyl-5-chloromethyl salicylaldehyde, triethylamine, and a second organic solvent, stirring, and filtering to obtain a chiral Salen ligand; S3, titanium tetraisopropoxide and dichloromethane are mixed to obtain a mixed solution, the chiral Salen ligand obtained in step S2 is mixed with the mixed solution and reacted to obtain a reacted material, the reacted material is dried and filtered to obtain chloromethyl chiral Salen Ti IV catalyst; S4, mixing the nanocrystalline cellulose and the alcohol solution and stirring, cooling and mixing with a silane coupling agent, followed by condensation, reflux and filtration to obtain functionalized modified cellulose; S5, the chloromethyl chiral Salen Ti obtained in step S3 IV The catalyst, the functionalized modified cellulose obtained in step S4, sodium hydroxide and the third organic solvent are mixed, and then stirred, condensed and refluxed, rotary evaporated and vacuum dried in sequence to obtain the functionalized modified cellulose loaded with Salen Ti IV catalyst.
[0011] Preferably, in step S1, the solid-to-liquid ratio of the (R,R)-cyclohexanediamine and the hydrochloric acid ether solution is 1 g: 3 to 3.6 mL; The concentration of the hydrochloric acid ether solution is 1.5-2.5 mol / L; The first organic solvent is dichloromethane and / or ethanol; The stirring time is 12 to 24 hours; The solid-liquid ratio of the mixed solution of 3,5-di-tert-butyl salicylaldehyde and MeOH-EtOH is 1 g: 18.75-25 mL; In the MeOH-EtOH mixed solution, the volume ratio of MeOH to EtOH is 1:0.5-2; The reaction time is 3 to 5 hours.
[0012] Preferably, in step S2, the preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde comprises: mixing 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde, tetrabutylammonium bromide and hydrochloric acid solution, stirring the mixture, extracting the mixture, washing, drying and filtering the mixture in sequence, and rotary evaporating and vacuum drying the liquid obtained after filtration to obtain 3-tert-butyl-5-chloromethyl salicylaldehyde; Preferably, in step S2, the weight ratio of 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde and tetrabutylammonium bromide is 5-6.25:2:1; The solid-liquid ratio of the 3,5-di-tert-butyl salicylaldehyde to the hydrochloric acid solution is 0.1-0.125 g:1 mL; The concentration of the hydrochloric acid solution is 36-38% by volume; The stirring conditions include: temperature of 30-50°C and time of 60-80 h.
[0013] Preferably, in step S2, the weight ratio of 3-tert-butyl-5-chloromethyl salicylaldehyde to triethylamine is 1.7 to 2:1; The solid-to-liquid ratio of the 3-tert-butyl-5-chloromethyl salicylaldehyde to the second organic solvent is 1 g: 15-21 mL; The second organic solvent is dichloromethane and / or ethanol; The molar ratio of (R,R)-cyclohexanediamine, 3,5-di-tert-butyl salicylaldehyde in step S1 and 3-tert-butyl-5-chloromethyl salicylaldehyde in step S2 is 1:1-1.2:1-1.2; The stirring time is 3 to 5 hours.
[0014] Preferably, in step S3, the solid-liquid ratio of titanium tetraisopropoxide to dichloromethane is 1 mmol: 10-30 mL The molar ratio of the chiral Salen ligand to titanium tetraisopropoxide is 1:1-1.2; The reaction time is 3 to 5 hours.
[0015] Preferably, in step S4, the solid-liquid ratio of the nanocrystalline cellulose and the alcohol solution is 1 g: 40-50 mL; The alcohol solution is selected from ethanol solution and / or methanol solution; The stirring conditions include: temperature of 60 to 80° C. and time of 10 to 14 h; The weight ratio of the nanocrystalline cellulose to the silane coupling agent is 1:0.5-0.8; The silane coupling agent is selected from one or more of KH570, vinyl trisilane and propenyl trisilane; The condensation reflux conditions include: temperature of 75-85°C and time of 3-5 hours.
[0016] Preferably, in step S5, the chloromethyl chiral Salen Ti IV The ratio of the catalyst, functionalized modified cellulose, sodium hydroxide and the third organic solvent is 1 g: 1 g: 1-1.2 g: 50-80 mL; The third organic solvent is chloroform and / or dichloromethane; The stirring conditions are: temperature of 50-70°C and time of 10-15h; The condensation reflux time is 40 to 60 hours; The vacuum drying conditions include: temperature of 40-50°C and time of 10-14 h.
[0017] The second aspect of the present invention provides a functional modified cellulose loaded SalenTi prepared by the above preparation method IV catalyst.
[0018] The third aspect of the present invention provides a functional modified cellulose loaded Salen Ti IV Application of catalysts in asymmetric oxidation of sulfides.
[0019] The beneficial effects of the present invention are: 1. Cellulose is renewable, widely available, biodegradable, and non-toxic, greatly reducing production costs and improving economic benefits. It also has a large number of hydroxyl groups and is easy to functionalize and modify, allowing for effective metal ion loading in a variety of ways.
[0020] 2. The functionalized modified cellulose loaded with Salen Ti IV The catalyst is reusable, and the reaction activity does not decrease significantly during the catalytic process. It has good stability and is an efficient, green and recyclable heterogeneous catalytic material.
[0021] 3. The functionalized modified cellulose loaded with Salen Ti IV When the catalyst is used in the asymmetric oxidation reaction of sulfide, the substrate is widely applicable and has good catalytic activity and selectivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 NCC@salen Ti of Example 1 IV Thermogravimetric curve of Figure 2 NCC@salen Ti of Example 1 IV X-ray diffraction pattern of Figure 3 NCC@salen Ti of Example 1 IV SEM image of . DETAILED DESCRIPTION
[0023] The following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.
[0024] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.
[0025] In addition, the technical solutions between the various embodiments provided by the present invention can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.
[0026] On the one hand, the present invention provides a functional modified cellulose loaded Salen Ti IV The preparation method of the catalyst comprises the following steps: S1, mixing (R,R)-cyclohexanediamine, ethereal hydrochloric acid solution, and a first organic solvent, and stirring to obtain a mixture, mixing the mixture, 3,5-di-tert-butyl salicylaldehyde, and a mixed solution of MeOH-EtOH, and then reacting to obtain a reaction mass; S2. Mixing the reaction material obtained in step S1, 3-tert-butyl-5-chloromethyl salicylaldehyde, triethylamine, and a second organic solvent, stirring, and filtering to obtain a chiral Salen ligand; S3, titanium tetraisopropoxide and dichloromethane are mixed to obtain a mixed solution, the chiral Salen ligand obtained in step S2 is mixed with the mixed solution and reacted to obtain a reacted material, the reacted material is dried and filtered to obtain chloromethyl chiral Salen Ti IV catalyst; S4, mixing the nanocrystalline cellulose and the alcohol solution and stirring, cooling and mixing with a silane coupling agent, followed by condensation, reflux and filtration to obtain functionalized modified cellulose; S5, the chloromethyl chiral Salen Ti obtained in step S3 IVThe catalyst, the functionalized modified cellulose obtained in step S4, sodium hydroxide and the third organic solvent are mixed, and then stirred, condensed and refluxed, rotary evaporated and vacuum dried in sequence to obtain the functionalized modified cellulose loaded with Salen Ti IV catalyst.
[0027] In a preferred embodiment of the present invention, in step S1, the solid-liquid ratio of the (R,R)-cyclohexanediamine to the hydrochloric acid ether solution is 1 g:3 to 3.6 mL; under this specific ratio, the reaction can be ensured to proceed completely, and the unilateral cyclohexanediamine is completely protected, so that a unilateral asymmetric product can be formed.
[0028] The ethereal hydrochloride solution in the present invention can be purchased or prepared by oneself, and the concentration of the ethereal hydrochloride solution is 1.5 to 2.5 mol / L. In a specific embodiment, the ethereal hydrochloride solution is prepared by oneself, and the concentration is 2 mol / L.
[0029] In step S1 of the present invention, the amount of the first organic solvent used only needs to be sufficient to dissolve all the materials.
[0030] Preferably, the first organic solvent is dichloromethane and / or ethanol; in a specific embodiment, the first organic solvent is dichloromethane.
[0031] Furthermore, in step S1, stirring is preferably performed at room temperature, wherein the stirring time is 12 to 24 hours.
[0032] In the specific operation of step S1, since the ethereal hydrochloride solution is easily volatile, when adding the ethereal hydrochloride solution, it is preferably added under ice-water bath conditions, that is, the ethereal hydrochloride solution is added at 0-4°C. After the ethereal hydrochloride solution is added, stirring is carried out at room temperature.
[0033] In the present invention, the room temperature refers to 20-30°C.
[0034] In a specific embodiment of step S1 of the present invention, in order to ensure sufficient mixing reaction, it is preferred that the mixture and 3,5-di-tert-butyl salicylaldehyde are first fully mixed with a mixed solution of MeOH-EtOH to completely dissolve the solute therein, and then 4Å molecular sieves are added thereto for mixing, and then the reaction is carried out.
[0035] The 4Å molecular sieve is used to absorb water and prevent violent boiling. Generally, about 8 to 10 particles are added to the reaction system.
[0036] In a specific embodiment, the weight ratio of 3,5-di-tert-butyl salicylaldehyde and 4Å molecular sieve in step S1 is 1:1.
[0037] In step S1 of the present invention, the solid-liquid ratio of the mixed solution of 3,5-di-tert-butyl salicylaldehyde and MeOH-EtOH is 1 g: 18.75 ~ 25 mL.
[0038] The MeOH-EtOH mixed solution is obtained by mixing MeOH (methanol) and EtOH (ethanol), wherein the volume ratio of MeOH to EtOH in the MeOH-EtOH mixed solution is 1:0.5-2. In a specific embodiment, the volume ratio of MeOH to EtOH is 1:1.
[0039] In step S1, the reaction is preferably carried out at room temperature, wherein the reaction time is 3 to 5 hours.
[0040] In step S2 of the present invention, since 3-tert-butyl-5-chloromethyl salicylaldehyde is not very stable and easily hydrolyzed, it is usually prepared and used immediately. The preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde comprises: mixing 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde, tetrabutylammonium bromide and hydrochloric acid solution, stirring the mixture, extracting the mixture, washing, drying and filtering the mixture in sequence, and rotary evaporating and vacuum drying the liquid obtained after filtration to obtain 3-tert-butyl-5-chloromethyl salicylaldehyde.
[0041] In the preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde, the weight ratio of the 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde and tetrabutylammonium bromide is 5~6.25:2:1; the solid-liquid ratio of the 3,5-di-tert-butyl salicylaldehyde to the hydrochloric acid solution is 0.1~0.125g:1 mL.
[0042] Preferably, the concentration of the hydrochloric acid solution is 36-38% by volume; the hydrochloric acid solution is concentrated hydrochloric acid.
[0043] Preferably, in the preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde, the stirring conditions include: temperature of 30 to 50° C. and time of 60 to 80 h.
[0044] In a specific preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde, extraction is performed with anhydrous ether 3 to 5 times, the lower organic phase is collected, and then the organic phase is washed 3 to 5 times with a 5wt% sodium bicarbonate solution and a saturated NaCl solution, respectively. The organic phase is then dried over anhydrous magnesium sulfate and filtered. The filtered liquid is rotary evaporated and vacuum dried (the product is fully dried, preferably vacuum dried at 50°C for 12 hours) to obtain 3-tert-butyl-5-chloromethyl salicylaldehyde.
[0045] Among them, the structure of 3-tert-butyl-5-chloromethyl salicylaldehyde is as follows, The reaction formula for preparing 3-tert-butyl-5-chloromethyl salicylaldehyde is as follows: In step S2 of the present invention, the weight ratio of the 3-tert-butyl-5-chloromethyl salicylaldehyde to triethylamine is 1.7 to 2: 1; the solid-liquid ratio of the 3-tert-butyl-5-chloromethyl salicylaldehyde to the second organic solvent is 1 g: 15 to 21 mL; and the second organic solvent is dichloromethane and / or ethanol.
[0046] In a specific embodiment, the second organic solvent is dichloromethane.
[0047] The molar ratio of (R,R)-cyclohexanediamine in step S1, 3,5-di-tert-butyl salicylaldehyde in step S1, and 3-tert-butyl-5-chloromethyl salicylaldehyde in step S2 is 1:1-1.2:1-1.2.
[0048] In a specific embodiment, the molar ratio of (R,R)-cyclohexanediamine in step S1, 3,5-di-tert-butyl salicylaldehyde in step S1, and 3-tert-butyl-5-chloromethyl salicylaldehyde in step S2 is 1:1:1.
[0049] In step S2, the mixture is preferably stirred at room temperature for 3 to 5 h.
[0050] In step S2, after the stirring is completed, suction filtration is further performed, and the liquid obtained after the filtration is dried with anhydrous magnesium sulfate and then filtered (the anhydrous magnesium sulfate after drying is removed). The liquid obtained after filtration is then recrystallized with anhydrous ethanol and then subjected to column chromatography (the purpose of recrystallization and column chromatography is to purify) to obtain a chiral Salen ligand.
[0051] The structure of the chiral Salen ligand is as follows, The reaction formula for preparing the chiral Salen ligand in the above steps S1 and S2 is as follows: In step S3, the solid-liquid ratio of titanium tetraisopropoxide to dichloromethane is 1 mmol:10-30 mL; in a specific embodiment, the solid-liquid ratio of titanium tetraisopropoxide to dichloromethane is 1 mmol:20 mL.
[0052] Preferably, in step S3, the molar ratio of the chiral Salen ligand to titanium tetraisopropoxide is 1:1-1.2.
[0053] In a specific embodiment, in step S3, the molar ratio of the chiral Salen ligand to titanium tetraisopropoxide is 1:1.2.
[0054] Furthermore, the reaction time in step S3 is 3 to 5 hours; in a specific embodiment, the reaction time in step S3 is 3 hours.
[0055] In a specific embodiment of step S3, two drops of water are added to the reacted material (the purpose of adding water is to promote the hydrolysis of titanium to form titanium dioxide particles, so that excess titanium can be removed), and then dried with anhydrous magnesium sulfate, followed by suction filtration. The liquid phase material obtained after filtration is subjected to reduced pressure distillation to remove the solvent, and finally vacuum dried (the product is fully dried, preferably vacuum dried at 50°C for 12h) to obtain chloromethyl chiral Salen Ti IV catalyst.
[0056] The chloromethyl chiral Salen Ti IV The structure of the catalyst is as follows, Preparation of chloromethyl chiral Salen Ti in step S3 IV The reaction equation of the catalyst is as follows: The solid-liquid ratio of the nano-microcrystalline cellulose and the alcohol solution of the present invention is 1 g: 40-50 mL.
[0057] Wherein, in step S4, the alcohol solution is selected from ethanol solution and / or methanol solution, and is further ethanol solution; in a specific embodiment, the concentration of the ethanol solution is 95% by volume.
[0058] In step S4, the stirring conditions include: a temperature of 60 to 80° C. and a time of 10 to 14 hours; after the stirring is completed, the mixture is cooled to room temperature and then mixed with the silane coupling agent.
[0059] Wherein, in step S4, the weight ratio of the nanocrystalline cellulose to the silane coupling agent is 1:0.5~1.5; the silane coupling agent is selected from one or more of KH570, vinyltrisilane and propenyltrisilane; in a specific embodiment, the silane coupling agent is selected from KH570.
[0060] In step S4, preferably, the condensation reflux conditions include: a temperature of 75 to 85° C. and a time of 3 to 5 hours.
[0061] Furthermore, after the condensation and reflux in step S4 are completed, suction filtration is performed, and the solid obtained after the filtration is washed and vacuum dried (the product can be fully dried, preferably vacuum dried at 50° C. for 12 hours) to obtain functionalized modified cellulose.
[0062] In step S5 of the present invention, in order to ensure that the raw materials are fully mixed, the chloromethyl chiral Salen TiIV catalyst obtained in step S3 and the functionalized modified cellulose obtained in step S4 are preferably fully dissolved in a third organic solvent, and then a small amount of sodium hydroxide is added thereto, mixed, and then stirred.
[0063] Wherein in step S5, chloromethyl chiral Salen Ti IV The usage ratio of the catalyst, the functionalized modified cellulose, the sodium hydroxide and the third organic solvent is 1 g: 1 g: 1-1.2 mmol: 20-80 mL.
[0064] Preferably, the third organic solvent is chloroform and / or dichloromethane; in a specific embodiment, the third organic solvent is chloroform.
[0065] The stirring conditions in step S5 are: temperature of 50-70° C. and time of 10-15 h.
[0066] In the preferred case of step S5, the condensation reflux time is 40 to 60 hours, wherein the condensation reflux temperature can be any temperature that can ensure normal operation.
[0067] Further preferably, the vacuum drying conditions in step S5 include: a temperature of 40-50° C. and a time of 10-14 h.
[0068] The second aspect of the present invention provides a functional modified cellulose loaded SalenTi prepared by the above preparation method IV catalyst.
[0069] The third aspect of the present invention provides a functional modified cellulose loaded Salen Ti IV Application of catalysts in asymmetric oxidation of sulfides.
[0070] Furthermore, the specific operation of the sulfide asymmetric oxidation reaction includes: using sulfide substances as substrates, pure water as solvent, hydrogen peroxide as oxidant, adding the functionalized modified cellulose loaded with Salen Ti at room temperature IV Catalyst, to carry out the reaction.
[0071] The thioether substance can be selected from thioanisole, p-bromothioanisole, p-methoxythioanisole, p-nitrothioanisole or o-methoxythioanisole.
[0072] Specifically, the process of the above-mentioned sulfide asymmetric oxidation reaction is as follows: 0.0050 g of functionalized modified cellulose loaded with Salen Ti IV The catalyst was dissolved in 0.5-2 mL pure water, 1 mmol of substrate was added, and the mixture was stirred thoroughly. Then, 1.0-1.5 mmol of H2O2 was slowly added dropwise to the above system within 15 min. The reaction was allowed to proceed at room temperature for 1-1.5 h. The reaction process was tracked in real time by GC. After the reaction was completed, an appropriate amount of Na2SO3 was added to the reaction flask to consume the unreacted H2O2. The functionalized modified cellulose loaded Salen Ti was then filtered. IV The catalyst was repeatedly washed with water, dried under vacuum, and reused. CH2Cl2 (1 mL) was added to the filtered liquid phase for extraction to obtain a lower organic phase, which was dried over anhydrous Na2SO4 and then filtered. The filtered liquid material was subjected to column chromatography (ethyl acetate: n-hexane = 1:5) to obtain the pure product.
[0073] The catalyst prepared by the present invention uses cellulose as a carrier and adds a Salen ligand, which effectively solves the problems of difficulty in recycling metal-based catalysts, easy environmental pollution caused by catalyst residues, high production costs, and unstable binding between the catalyst and the substrate.
[0074] The present invention will be described in detail below through examples.
[0075] In the following examples, room temperature refers to 25°C; paraformaldehyde was purchased from Sinopharm Group with a CAS number of 30525-89-4; nanocrystalline cellulose was purchased from Maclean with a CAS number of 9004-34-6; and 4Å molecular sieve was purchased from Anage with a CAS number of 70955-01-0.
[0076] Example 1 S1. In an ice-water bath (0-4°C), add 1.5 mL of a 2 mol / L hydrochloric acid ether solution and 50 mL of dichloromethane to 0.5 g (4.3 mmol) of (R,R)-cyclohexanediamine. The mixture is stirred at room temperature for 15 h to obtain a mixture. The mixture and 1.0 g (4.3 mmol) of 3,5-di-tert-butyl salicylaldehyde are first mixed with 20 mL of a MeOH-EtOH mixed solution (the MeOH-EtOH mixed solution is obtained by mixing MeOH and EtOH, wherein the volume ratio of MeOH to EtOH in the MeOH-EtOH mixed solution is 1:1) to completely dissolve the solute therein. Subsequently, 1.0 g of active 4Å molecular sieves is added thereto, and the mixture is reacted at room temperature for 4 h to obtain a reaction mass. S2. Add 2.5 g of 3,5-di-tert-butyl salicylaldehyde, 0.8 g of paraformaldehyde, 0.4 g of tetrabutylammonium bromide and 20 mL of hydrochloric acid solution (concentration of 37% by volume, i.e., concentrated hydrochloric acid) to a round-bottom flask, mix and stir at a constant temperature of 40 ° C for 72 h, then extract with anhydrous ether three times, collect the organic phase, and then wash the organic phase with 5wt% sodium bicarbonate solution and saturated NaCl solution three times, then dry over anhydrous magnesium sulfate, and then filter. The liquid obtained after filtration is rotary evaporated and vacuum dried (vacuum dried at 50 ° C for 12 h) to obtain a yellow solid 3-tert-butyl-5-chloromethyl salicylaldehyde; add the reaction material obtained in step S1, 1.0 g (4.4 mmol) of 3-tert-butyl-5-chloromethyl salicylaldehyde, 0.5 g of triethylamine and 20 mL of dichloromethane to a round-bottom flask, mix and stir at room temperature for 4 h, then filtered, the liquid obtained after filtration was dried over anhydrous magnesium sulfate, then filtered, and then the filtered liquid was recrystallized with anhydrous ethanol, and then subjected to column chromatography to obtain a light yellow powder chiral Salen ligand; the result of nuclear magnetic resonance characterization of the Salen ligand was: 1 H NMR (CDCl3, 400MHz): δ ppm 14.27 (s, 1 H), 13.65 (s, 1 H), 8.43 (s, 1 H), 8.30 (s, 1 H), 7.32 (d, 1 H), 7.24 (d, 1 H), 6.97 (d, 1 H), 6.88 (d, 1 H), 4.42 (s, 2 H), 3.54–3.31 (m, 2 H), 1.96–1.45 (m, 8 H), 1.40 (s, 9 H), 1.21 (s, 18 H); S3, titanium tetraisopropoxide is mixed with anhydrous dichloromethane to fully dissolve titanium tetraisopropoxide, the solid-liquid ratio of titanium tetraisopropoxide to anhydrous dichloromethane is 1 mmol: 20 mL, and a mixed solution is obtained. The mixed solution is added to the chiral Salen ligand obtained in step S2, and the molar ratio of the chiral Salen ligand to titanium tetraisopropoxide is controlled to be 1: 1.2, and then reacted at 25 ° C for 3 hours to obtain a reacted material, two drops of water are added to the reacted material, and then dried with anhydrous magnesium sulfate, and then filtered, and the liquid phase material obtained after filtration is subjected to reduced pressure distillation to remove the solvent, and finally vacuum dried (vacuum dried at 50 ° C for 12 hours) to obtain chloromethyl chiral Salen Ti IV Catalyst; The chloromethyl chiral Salen Ti IV The catalyst was tested by infrared FT-IR. The results of infrared FT-IR (KBr): γmax / cm −13439, 3315, 2971, 2930, 2886, 1655,1543, 1382, 1361, 1260, 1171, 1130, 1053, 988, 921, 884, 835, 518 cm −1 ; S4. Add 1.0 g of nanocrystalline cellulose and 50 mL of 95% by volume ethanol solution into a three-necked flask, stir at 70°C for 12 h, cool to room temperature, add 1.4 g of silane coupling agent KH570 dropwise, mix, condense and reflux at 80°C for 4 h, and then filter. Wash and vacuum dry the solid obtained after filtration (vacuum drying at 50°C for 12 h) to obtain functionalized modified cellulose (NCC). S5, 1g of chloromethyl chiral Salen Ti obtained in step S3 IV The catalyst and 1 g of the functionalized modified cellulose obtained in step S4 were fully dissolved in 20 mL of chloroform, and then 1 mmol of sodium hydroxide was added and mixed. The mixture was then stirred at 60 ° C for 12 h, and then refluxed at 60 ° C for 40 h, and then rotary evaporated and vacuum dried (vacuum dried at 50 ° C for 12 h) to obtain functionalized modified cellulose loaded with Salen Ti. IV Catalyst (NCC@salen Ti IV ).
[0077] Test Example 1 The NCC@salen Ti of Example 1 was analyzed using a SDTQ600 series thermogravimetric analyzer manufactured by TA Corporation of the United States. IV The sample was subjected to thermogravimetric study. The mass of the material and its relationship with the ambient temperature and time were measured. By studying the thermogravimetric curve, we can understand the composition, thermal stability, thermal decomposition and generated products of the sample and its possible intermediate products, and thus have a comprehensive assessment of the thermal stability of the material. The test conditions are: temperature range 30℃~900℃, heating rate 10℃ / min, static air atmosphere; the thermogravimetric curve is as follows: Figure 1 shown.
[0078] from Figure 1 The thermogravimetric analysis curve of the present invention shows that the NCC@salen Ti IV It has good thermal stability within the experimental temperature range and long-term stability under low temperature conditions. The starting temperature of its thermal decomposition is 350°C, and the decomposition temperature range is 350-600°C. In this temperature range, the thermal decomposition of the material is mainly the combustion decomposition of organic matter, and then maintains a constant weight. After the organic matter is fully burned and decomposed, the mass of the remaining metal oxide no longer changes.
[0079] The NCC@salen Ti of Example 1 was measured using an X-ray diffractometer produced by Edinburgh Instruments. IV The sample is subjected to material structure analysis. Qualitative analysis of the compound can be performed by measuring the diffraction angle position (peak position). XRD diagram is as follows Figure 2 shown.
[0080] from Figure 2 As can be seen, NCC@salen Ti IV There are a large number of characteristic peaks in the XRD spectrum, indicating that the metal atoms are connected to the cellulose carrier by coordination and distributed on the surface of the cellulose carrier. This structure can effectively increase the dispersion of metal atoms and improve the utilization rate of metal atoms under a certain spatial structure, thereby improving the catalytic efficiency of the catalyst and improving the catalytic performance.
[0081] NCC@salen Ti of Example 1 IV The samples were observed by scanning electron microscope, and the SEM images were as follows Figure 3 As shown (magnification is 2000 times), according to Figure 3 Scanning electron microscopy results showed that the sample structure showed the basic morphology of cellulose, indicating that the cellulose structure was not destroyed after modification with chiral salen Ti.
[0082] Test Example 2 The chiral Salen Ti chloromethyl obtained in step S3 of Example 1 was used. IV Catalyst, NCC obtained in step S4 and NCC@salen Ti obtained in step S5 IVAs a catalyst, a sulfide asymmetric oxidation reaction is carried out. The specific operation of the sulfide asymmetric oxidation reaction includes: weighing 0.0050 g of the above-mentioned different catalysts and dissolving them in 1 mL of pure water, adding 1 mmol of substrate to each, stirring thoroughly, then slowly adding 1.2 mmol of H2O2 to each system within 15 minutes, reacting at room temperature for 1 hour, and using GC to track the reaction progress in real time. After the reaction is completed, an appropriate amount of Na2SO3 is added to each reaction bottle to consume the unreacted H2O2, and then filtering to obtain the catalyst, repeatedly washing it with water, and vacuum drying it for reuse. CH2Cl2 (1 mL) was added to the filtered liquid phase for extraction to obtain the lower organic phase (a small amount of the organic phase was taken for gas chromatography analysis: column temperature 180°C, vaporization chamber temperature and detection temperature were 250°C; the selectivity of the sulfoxide product was obtained), the organic phase was dried over anhydrous Na2SO4, and then filtered. The filtered liquid material was subjected to column chromatography (ethyl acetate: n-hexane = 1:5) to obtain the pure product and calculate the yield; the product was then subjected to high performance liquid chromatography HPLC analysis (detection wavelength 254 nm, n-hexane: isopropanol = 90:10) to obtain the optical purity, i.e., the ee value; a blank control group was set up, i.e., no catalyst was used, and the selectivity, yield and ee value of the blank control group were detected by the same method. The results are shown in Table 1.
[0083] Table 1 From the data in Table 1, we can see that NCC has no catalytic effect and cannot promote the forward reaction in the asymmetric oxidation of sulfide. Like the blank control group, no reaction occurs and the reaction rate is not changed. IV Catalyst and NCC@salen Ti IV It has a catalytic effect and can promote the forward reaction in the asymmetric oxidation of sulfides, but NCC@salen Ti IV Better catalytic performance.
[0084] Among them, the chiral Salen Ti IV Catalyst and NCC@salen Ti IV The chiral sulfoxide product obtained by the asymmetric catalytic oxidation reaction of sulfide as a catalyst was characterized by nuclear magnetic resonance. The characterization data are as follows: 1 H NMR (CDCl3, 500 MHz): δ (ppm): 7.52-7.55 (m, 2H, Ar H ), 7.37-7.42 (m, 3H, Ar H ),2.55-2.58 (s, 3H, Me). 13C NMR (CDCl3, 125 MHz): δ (ppm): 145.6, 131.1, 129.5,123.6, (Ar C ), 43.9 (S C H3).
[0085] Test Example 3 The NCC@salen Ti obtained in step S5 of Example 1 was IV As a catalyst, asymmetric oxidation of sulfide was carried out with different substrates. The specific operation of the asymmetric oxidation of sulfide was the same as that in Test Example 2, except that the substrates were different. The structure of the obtained product was the same as that of the product in Test Example 2. The selectivity, yield, and ee value of the asymmetric oxidation of sulfide with different substrates were tested according to the method in Test Example 2. The results are shown in Table 2.
[0086] Table 2 From the data in Table 2, we can see that the NCC@salen Ti prepared in Example 1 IV The catalyst has excellent universality. When the reaction substrate is p-bromoanisole, the yield is as high as 98%, the selectivity is as high as 92%, and the ee value is as high as 94%. When the reaction substrate is p-methoxyanisole, the yield is as high as 99%, the selectivity is as high as 98%, and the ee value is as high as 97%. When the reaction substrate is p-nitroanisole, the yield is as high as 99%, the selectivity is as high as 96%, and the ee value is as high as 95%. When the reaction substrate is o-methoxyanisole, the yield is as high as 95%, the selectivity is as high as 91%, and the ee value is as high as 87%.
[0087] Test Example 4 The NCC@salen Ti obtained in step S5 IV Catalyst reusability test: The asymmetric oxidation reaction of sulfide was carried out according to the operation in Test Example 2, and the NCC@salen Ti IV As a catalyst, NCC@salen Ti is recovered after each reaction. IV , and then the recycled NCC@salen Ti IV The asymmetric oxidation reaction of sulfide was repeated for 0 cycles (i.e., the first use without recycling), 1, 2, 3, 4, 5, and 6 cycles to investigate the performance of the recycled catalyst. The selectivity, yield, and ee value of the corresponding reactions were measured according to the method in Test Example 2, as shown in Table 3 below.
[0088] Table 3 From the data in Table 3, it can be seen that the functionalized modified cellulose loaded with Salen Ti obtained in the present invention IV The number of times the catalyst was recycled had little effect on the selectivity, yield, and EE of the asymmetric oxidation of sulfides. Both the unrecycled catalyst and the catalyst recycled six times achieved selectivities, yields, and EE values exceeding 90%, with high yields of chiral sulfoxide products. This demonstrates that the catalytic effect of the recycled catalyst remains significant, and the performance of the recycled catalyst is excellent, achieving the goals of recycling, cost savings, and supporting the development of green chemistry.
[0089] It should be understood that parts not elaborated in detail in this specification belong to the prior art.
[0090] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.
Claims
1. A functionalized modified cellulose loaded with Salen Ti IV The method for preparing a catalyst is characterized in that: The following steps are involved: S1, mixing (R,R)-cyclohexanediamine, ethereal hydrochloric acid solution, and a first organic solvent, and stirring to obtain a mixture, mixing the mixture, 3,5-di-tert-butyl salicylaldehyde, and a mixed solution of MeOH-EtOH, and then reacting to obtain a reaction mass; S2. Mixing the reaction material obtained in step S1, 3-tert-butyl-5-chloromethyl salicylaldehyde, triethylamine, and a second organic solvent, stirring, and filtering to obtain a chiral Salen ligand; S3, titanium tetraisopropoxide and dichloromethane are mixed to obtain a mixed solution, the chiral Salen ligand obtained in step S2 is mixed with the mixed solution and reacted to obtain a reacted material, the reacted material is dried and filtered to obtain chloromethyl chiral Salen Ti IV catalyst; S4, mixing the nanocrystalline cellulose and the alcohol solution and stirring, cooling and mixing with a silane coupling agent, followed by condensation, reflux and filtration to obtain functionalized modified cellulose; S5, the chloromethyl chiral Salen Ti obtained in step S3 IV The catalyst, the functionalized modified cellulose obtained in step S4, sodium hydroxide and the third organic solvent are mixed, and then stirred, condensed and refluxed, rotary evaporated and vacuum dried in sequence to obtain the functionalized modified cellulose loaded with Salen Ti IV catalyst.
2. The preparation method according to claim 1, characterized in that In step S1, the solid-liquid ratio of the (R,R)-cyclohexanediamine and the hydrochloric acid ether solution is 1 g: 3 to 3.6 mL; The concentration of the hydrochloric acid ether solution is 1.5-2.5 mol / L; The first organic solvent is dichloromethane and / or ethanol; The stirring time is 12 to 24 hours; The solid-liquid ratio of the mixed solution of 3,5-di-tert-butyl salicylaldehyde and MeOH-EtOH is 1 g: 18.75-25 mL; In the MeOH-EtOH mixed solution, the volume ratio of MeOH to EtOH is 1:0.5-2; The reaction time is 3 to 5 hours.
3. The preparation method according to claim 1, characterized in that In step S2, the preparation method of 3-tert-butyl-5-chloromethyl salicylaldehyde includes: mixing 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde, tetrabutylammonium bromide and hydrochloric acid solution and stirring, then extracting, and then washing, drying and filtering in sequence, and rotary evaporating and vacuum drying the liquid obtained after filtration to obtain 3-tert-butyl-5-chloromethyl salicylaldehyde.
4. The preparation method according to claim 3, characterized in that In step S2, the weight ratio of 3,5-di-tert-butyl salicylaldehyde, paraformaldehyde and tetrabutylammonium bromide is 5-6.25:2:1; The solid-liquid ratio of the 3,5-di-tert-butyl salicylaldehyde to the hydrochloric acid solution is 0.1-0.125 g:1 mL; The concentration of the hydrochloric acid solution is 36-38% by volume; The stirring conditions include: temperature of 30-50°C and time of 60-80 h.
5. The preparation method according to claim 1 or 3, characterized in that In step S2, the weight ratio of 3-tert-butyl-5-chloromethyl salicylaldehyde to triethylamine is 1.7 to 2:1; The solid-to-liquid ratio of the 3-tert-butyl-5-chloromethyl salicylaldehyde to the second organic solvent is 1 g: 15-21 mL; The second organic solvent is dichloromethane and / or ethanol; The molar ratio of (R,R)-cyclohexanediamine, 3,5-di-tert-butyl salicylaldehyde in step S1 and 3-tert-butyl-5-chloromethyl salicylaldehyde in step S2 is 1:1-1.2:1-1.2; The stirring time is 3 to 5 hours.
6. The preparation method according to claim 1, characterized in that In step S3, the solid-liquid ratio of titanium tetraisopropoxide to dichloromethane is 1 mmol:10-30 mL; The molar ratio of the chiral Salen ligand to titanium tetraisopropoxide is 1:1-1.2; The reaction time is 3 to 5 hours.
7. The preparation method according to claim 1, characterized in that In step S4, the solid-liquid ratio of the nanocrystalline cellulose and the alcohol solution is 1 g: 40-50 mL; The alcohol solution is selected from ethanol solution and / or methanol solution; The stirring conditions include: temperature of 60 to 80° C. and time of 10 to 14 h; The weight ratio of the nanocrystalline cellulose to the silane coupling agent is 1:0.5-1.5; The silane coupling agent is selected from one or more of KH570, vinyl trisilane and propenyl trisilane; The condensation reflux conditions include: temperature of 75-85°C and time of 3-5 hours.
8. The preparation method according to claim 1, characterized in that In step S5, chloromethyl chiral Salen Ti IV The ratio of the catalyst, functionalized modified cellulose, sodium hydroxide and the third organic solvent is 1 g: 1 g: 1-1.2 mmol: 20-80 mL; The third organic solvent is chloroform and / or dichloromethane; The stirring conditions are: temperature of 50-70°C and time of 10-15h; The condensation reflux time is 40 to 60 hours; The vacuum drying conditions include: temperature of 40-50°C and time of 10-14 h.
9. The functionalized modified cellulose loaded SalenTi prepared by the preparation method according to any one of claims 1 to 8 IV catalyst.
10. The functionalized modified cellulose-loaded Salen Ti according to claim 9 IV Application of catalysts in asymmetric oxidation of sulfides.