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Nano magnetic microsphere supported TEMPO catalyst and synthetic method and application thereof

A nano-magnetic and synthetic method technology, applied in the direction of chemical instruments and methods, physical/chemical process catalysts, organic compounds/hydrides/coordination complex catalysts, etc., can solve the problem of coalescence, affecting secondary dispersion, and increasing reaction costs And other issues

Active Publication Date: 2014-10-15
ZHEJIANG UNIV OF TECH
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Problems solved by technology

[0004] Although TEMPO is an effective alcohol oxidation catalyst, there are the following problems in use: (1) TEMPO is a heterocyclic small molecule compound, which is expensive and difficult to separate and apply mechanically, resulting in increased reaction costs; (2) Residual TEMPO affects the purity of the product Although the laboratory can use column chromatography and other means to purify the product, it is more difficult to implement in large-scale industrial production
The application of this nanocatalyst has the following problems: (1) In the absence of stabilizers, most of the magnetic nanoparticles are agglomerated, resulting in a decrease in active sites and a decrease in specific surface area
Nanoparticle-supported catalysts are prone to agglomeration and coagulation during the preparation and reaction process, resulting in catalyst activity far from the expected value; (2) Inorganic magnetic nanoparticles (usually iron or cobalt oxides) in the Anelli method (TEMPO / NaBr / NaClO) and other oxidation systems are unstable (Fe 2+ Oxidized to Fe 3+ ), leading to magnetic loss; (3) functionalization of inorganic magnetic nanoparticles is difficult, the preparation steps of the catalyst are complicated, and the loading capacity is difficult to control
[0011] In the previous work, our laboratory has published a synthesis method of nano-magnetic microsphere-supported TEMPO catalyst (ChemCatChem, DOI: 10.1002 / cctc.201200459), the catalytic activity is equivalent to that of homogeneous TEMPO, and there are still some problems in the purification and recovery process. The coalescence problem that often occurs in the application of nanomaterials, in addition, the hydrophobic polymer surface environment affects the secondary dispersion of this nanoscale catalyst in the heterogeneous reaction system

Method used

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  • Nano magnetic microsphere supported TEMPO catalyst and synthetic method and application thereof
  • Nano magnetic microsphere supported TEMPO catalyst and synthetic method and application thereof
  • Nano magnetic microsphere supported TEMPO catalyst and synthetic method and application thereof

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preparation example Construction

[0054] Preparation of Nanomagnetic Microsphere II:

[0055] FeCl 3 ·6H 2 O (24.4255 g, 0.09 mol) and FeSO 4 ·7H 2 O (16.7044g, 0.06mol) was added to 200ml of deionized water, heated to 90°C, and then 60ml of ammonia water, 3g of oleic acid, and 1g of undecylenic acid were added dropwise. After reacting for 3h, the precipitate was washed with deionized water to medium properties, to obtain nano-Fe 3 o 4 magnetic core.

[0056] 10g nanometer Fe 3 o 4 The magnetic core is mixed with 10g styrene, 10g p-chloromethylstyrene, 1g divinylbenzene and 2g hexadecane to form an oil phase, then 300ml deionized water and 3g sodium lauryl sulfate are mixed to form a water phase, and the Add the above oil phase to the water phase drop by drop under certain conditions to obtain a black suspension; place the black suspension in an ice-water bath, use a 300W cell pulverizer to finely emulsify it for 30 minutes, pour the fine emulsion into a reaction vessel, and add 0.1g K 2 S 2 o 8 , ...

Embodiment 1

[0062] Put 4-hydroxy TEMPO (5mmol), bromoacetic acid (5mmol), dichloromethane (25ml) in a round bottom flask, N 2 Stir in an ice-water bath under protection, then add DCC (dicyclohexylcarbodiimide, 6mmol), DMAP (4-dimethylaminopyridine, 0.05mmol) dropwise into the reaction system, and stir at room temperature for 12h; The product is washed and dried to obtain a red product;

[0063] Put magnetic microsphere II (containing Cl 5mmol), imidazole (10 mmol), appropriate amount of benzene in a round bottom flask, N 2 Under protection, stir and react in an oil bath at 80°C for 24 hours, wash with acetone, filter, extract, and dry to obtain the magnetic microspheres grafted with imidazole III;

[0064] The above red product (5 mmol), imidazole-loaded magnetic microspheres III (containing 2.5 mmol of imidazole groups) were added to the reactor, benzene was used as solvent, and N 2 Stir the reaction in an oil bath at 80°C for 12 hours under protection, wash and dry the reaction produc...

Embodiment 2

[0068] 4-Hydroxy TEMPO (2.58g, 0.015mol) was dissolved in acetone (25ml), NaH (0.6g, 0.015mol) was added, the mixture was stirred at room temperature for 30min, and 1,4-dibromobutane (4.86g , 0.0225mol), stirred at room temperature for 3h, after the reaction was over, the acetone was distilled off under reduced pressure, and the resulting solid was dissolved in distilled water; the aqueous layer was extracted three times with dichloromethane, and then Na 2 SO 4 Dry the extract containing organic matter, and then vacuum dry to obtain a concentrated solution; use a chromatographic column (petroleum ether / ethyl acetate = 9:1) to separate and dry the concentrated solution;

[0069] Then the first step reaction product (5mmol), imidazole-loaded magnetic microsphere III (containing imidazole group 5mmol) prepared according to the method of Example 1, K 2 CO 3 Add (5mmol) into a round bottom flask, use acetone as a solvent, stir and react at 80°C for 6h; cool to room temperature, a...

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Abstract

The invention discloses a nano magnetic microsphere supported TEMPO catalyst and a synthetic method and application thereof. The structure of the catalyst is shown as a formula (I-1) or formula (I-2); the catalyst (I-1) is composed of a nano magnetic microsphere (II), a linking group A and a catalyst TEMPO; one end of the linking group A is connected with C* of the nano magnetic microsphere II, and the other end is connected with the catalyst TEMPO; the linking group A is selected from the groups shown as A (1), (2), (3) and (4); the cationic part (III) of the catalyst (I-2) is obtained by connecting the linking group (IV) and the C* of the nano magnetic microsphere (II); the nano magnetic microsphere (II) is formed by wrapping a polystyrene-poly p-chloromethyl styrene copolymer coating layer outside the nano Fe3O4 magnetic core. The catalyst involved in the invention can be used in the oxidation of alcohols. The catalyst provided by the invention does not agglomerate or coagulate in the preparation and reaction process, has significantly increased catalytic activity and phase transfer catalytic function.

Description

technical field [0001] The invention relates to a nano-magnetic microsphere-loaded TEMPO catalyst, a synthesis method and application thereof. technical background [0002] The selective oxidation of alcohols to corresponding carbonyl compounds such as ketones and aldehydes is one of the most important chemical reactions in industrial synthesis and laboratory research. Traditional alcohol oxidation methods mainly use stoichiometric high-valence transition metal salts (such as Collin’s reagent Cr(IV)) or organic oxides. This type of oxidant has high cost, low selectivity, and heavy metal pollutants will be generated during the reaction process. As resource and environmental issues become increasingly prominent, the research and development of green and efficient non-heavy metal oxidants and catalysts has become a hot spot in alcohol oxidation reactions. [0003] 2,2,6,6-Tetramethylpiperidine-nitrogen-oxide (TEMPO) is used as free radical scavenger, polymerization inhibitor, ...

Claims

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Application Information

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IPC IPC(8): B01J31/28C07C47/54C07C45/30
Inventor 王建黎谭明郑智
Owner ZHEJIANG UNIV OF TECH
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