KR100926128B1 - Magnetic nanocatalyst and method for the preparation thereof - Google Patents

Abstract

The present invention relates to a magnetic nanocatalyst and a method for preparing the same, wherein the magnetic nanocatalyst supported by the transition metal nanoparticle and the magnetic nanoparticle according to the present invention provides excellent reactivity in various organic reactions, and exhibits magnetic properties. It can be separated and recycled to a magnet after the reaction, so that it can be usefully used as a catalyst in various reactions such as ring opening reaction of epoxy compound, oxidation reaction of alcohol, hydrogenation reaction, carbon-carbon coupling reaction or alkylation reaction.

Description

Magnetic nanocatalyst and its manufacturing method {MAGNETIC NANOCATALYST AND METHOD FOR THE PREPARATION THEREOF}

1 shows a transmission electron microscope (TEM) photograph of the palladium-iron oxide nanocatalyst prepared in Example 1 of the present invention;

2 is a magnetic characteristic analysis result of the superconducting quantum interference device (SQUID) of the palladium-iron oxide nanocatalyst prepared in Example 1 of the present invention,

Figure 3 is a photograph showing the experimental process (a) of the hydrocracking reaction of epichlorine using the palladium-iron oxide nanocatalyst prepared in Example 1 of the present invention and the catalyst recovery method (b) after the reaction.

The present invention is used as a catalyst in various organic reactions, and relates to a magnetic nanocatalyst and a method for preparing the same, which can be separated and recycled into a magnet after the reaction.

Nanocatalysts are distinguished from conventional catalysts due to their very high reaction surface area and surface specificity and are used in various organic reactions (Burda, C. et al. , Chem. Rev. 2005 , 105 , 1025); [Astruc , D. et al. , Angew. Chem. Int. Ed. 2005 , 44 , 7852). However, such nanocatalysts are difficult to apply industrially due to the coagulation phenomenon during the reaction process, the reactivity is lowered or difficult to separate from the mixture after the reaction. In order to solve these problems, most nanocatalysts are used by immobilization on surfaces of inorganic oxides, organic polymers, dendrimers, and ionic liquids (Corma, A. et al., Science 2006 , 313 , 332; Oyamada; , H. et al. , Chem. Commun. 2006 , 4297; Song, H., et al. , J. Am. Chem. Soc. 2006 , 128 , 3027; Yamada, YMA et al . , Org. Lett. 2006 , 8 , 1375; see Wu, L. et al . , Org. Lett. 2006 , 8 , 3605; and Wang, Y. et al. , Chem. Commun. 2006 , 2545). However, the catalysts mentioned above have a problem in that the synthesis process is difficult or the catalyst must be separated through a separate filtration process after the reaction.

On the other hand, the magnetic nanoparticles exhibit unique magnetic properties compared to the existing mass material consisting of a plurality of magnetic domains because the individual particles become a single magnetic domain. This magnetic property has shown important potential in many fields such as high density magnetic storage devices, drug carriers and sensors. In particular, magnetic nanoparticles may be prepared by a support of a homogeneous catalyst (Stevens, PD et al . , Org. Lett. 2005 , 7 , 2085; Hu, A. et al. , J. Am. Chem. Soc. 2005 , 127 , 12486). Or by mixing with a heterogeneous catalyst (see Kim, J. et al. , Angew. Chem. Int. Ed. 2006 , 45 , 4789; Yi, DK et al. , Chem. Mater. 2006 , 18 , 2459). Recently, many studies have been conducted because it is easy to separate from the reaction mixture using an external magnet without a separate filtration process. However, most methods suffer from low reactivity, decomposition of catalysts, leaching of surface metals, and difficult synthesis methods.

In addition, Korean Patent Publication No. 2003-71233 discloses a reusable organometallic catalyst in which an organo-metal complex is immobilized on a surface of a magnetic nanoparticle, but the scope of the catalyst is limited to a homogeneous catalyst, and a separate functional organic ligand. It is difficult to synthesize the organic-metal complex to form a complex on the surface of the magnetic nanoparticles.

Accordingly, it is an object of the present invention to provide a magnetic nanocatalyst and a method for preparing the same, which can be separated and recycled into a magnet and provide high reactivity.

In order to achieve the above object, the present invention provides a magnetic nanocatalyst in which the transition metal nanoparticles and the magnetic nanoparticles are supported on a carrier.

In addition, the present invention comprises the steps of (1) mixing the transition metal complex, metal grasp ligand and carrier precursor to form a transition metal nanoparticles, and then mixing the resulting transition metal nanoparticles with magnetic nanoparticles; And (2) provides a method for producing a magnetic nanocatalyst comprising the step of sol-gel reaction by adding water to the resulting mixture.

Hereinafter, the present invention will be described in more detail.

The magnetic nanocatalyst according to the present invention is characterized in that the transition metal nanoparticles and the magnetic nanoparticles are supported on a carrier together. The magnetic nanocatalyst of the present invention having such characteristics provides excellent reactivity in various organic reactions, and Due to its specific properties, it is easy to separate and recover with a magnet after the reaction, and there is no change in excellent catalytic activity even when the recovered catalyst is recycled for several to several tens of times. Therefore, ring opening reaction of epoxy compound, oxidation reaction of alcohol, It can be usefully used in various reactions such as hydrogenation reaction, carbon-carbon coupling reaction or alkylation reaction.

In the magnetic nanocatalyst of the present invention, the transition metal nanoparticles and the magnetic nanoparticles are supported on the carrier at a ratio of 1: 0.1 to 100, the transition metal nanoparticles have a particle size range of 1 to 100 nm, and the magnetic nanoparticles are 1 And a particle size range of 500 nm.

The magnetic nanocatalyst of the present invention forms a metal nanoparticle by mixing and heating a transition metal complex, a metal grasp ligand, and a carrier precursor, mixes the resulting metal nanoparticle with the magnetic nanoparticle, and then adds water to the resulting mixture. It can be obtained by addition and sol-gel reaction.

Transition metals included in the transition metal complex are preferably Pd, Pt, Ru, Os, Rh, Ir, Re, Mo, W, Cu, Ag, Au, Zn, Hf, Ta, Nb and V, etc. More preferably palladium (Pd). Two or more kinds of transition metal complexes may be used, and the metals contained in the complex may be different.

Coordination ligands suitable for complex formation include anionic ligands (formal anions) and neutral neutrals (formal neutrals). The anionic ligands include hydride (H ^-), chloride (Cl ^-), cyanide (CN ^-) or an acetyl (CH ₃ CO ^-) and the like are included, with a neutral property ligand is triphenylphosphine (P (C ₆ H ₅ ) ₃ ), dibenzylideneacetone (C ₆ H ₅ CH = CHCOCH = CHC ₆ H ₅ ), carbonyl (CO) or diene (CH ₂ CHCHCH ₂ ), and the like.

In particular, examples of palladium complexes include palladium (II) acetate (Pd (OAc) ₂ ), palladium (II) chloride (Pd (II) Cl ₂ ), palladium (II) nitrate (Pd (NO ₃ ) ₂ ), tetra Keystriphenylphosphinepalladium (0) (Pd [P (C ₆ H ₅ ) ₃ ] ₄ ), trisdiglylideneacetonedipalladium (0) chloroform adduct ((C ₆ H ₅ CH = CHCOCH = CHC ₆ H ₅ ) ₃ Pd ₂ CHCl ₃ or mixtures thereof, and preferably palladium (II) acetate (Pd (OAc) ₂ ).

In addition, the metal grab ligand in the present invention refers to a material that stabilizes the resulting metal nanoparticles to form a nanoparticle of a certain size, such materials are commonly used organic acids (C _n COOH, C _n : hydrocarbon, 7 ≦ _n ≦ 30), organic amine (C _n NH ₂ , C _n : hydrocarbon, 7 ≦ _n ≦ 30), alkane thiol (C _n SH, C _n : hydrocarbon, 7 ≦ _n ≦ 30), phosphine (C _n P, C _n : hydrocarbon, 7 ≦ _n ≦ 30), or polymer (10,000 ≦ M _n ≦ 100,000) and the like, oleic acid, oleyl amine, dodecane thiol, triphenyl phosphine, polyvinyl pyrrolidone, polyethylene Glycols and mixtures thereof, and the like.

The metal ligne ligand may be used in an amount ranging from 10 to 1000 moles, preferably 20 to 300 moles, based on 1 mole of the transition metal complex.

In the present invention, as a reducing agent for reducing the transition metal complex, hydrogen, metal hydrides, alcohols can be used, and preferred examples thereof include ethanol, n -butanol, sec -butanol or i -butanol.

Meanwhile, the carrier precursor may be an alkoxide precursor of a metal oxide that is commonly used as a carrier, and may be tetraalkyl orthosilicate (Si (OR) ₄ ) or titanium tetra as a precursor of silica, titania, alumina, zirconia or magnesia, respectively. Alkoxide (Ti (OR) ₄ ), Aluminum trialkoxide (Al (OR) ₃ ), Zirconium alkoxide (Zr (OR) ₄ ), Magnesium alkoxide (Mg (OR) ₂ ) or a mixture thereof may be used, and the like. Wherein R is an alkyl group having 1 to 4 carbon atoms such as methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl or s-butyl.

The carrier precursor may be used in an amount ranging from 10 to 1000 moles, preferably 50 to 300 moles, based on 1 mole of the transition metal complex.

In the preparation method of the present invention, the preparation of the metal nanoparticles is preferably carried out in a solvent. As a solvent, an organic compound capable of dissolving a transition metal complex is tetrahydrofuran (THF), dichloromethane, chloroform, toluene, ethyl acetate or And mixtures thereof.

In the present invention, the reaction for producing the metal nanoparticles is preferably carried out at a temperature range of 20 to 500 ℃, preferably 20 to 250 ℃, the time required to complete the reaction is the reaction temperature, the reactants used Depending on the molar ratio of these, but is preferably about 5 minutes to 20 hours.

Subsequently, magnetic nanoparticles are mixed with the produced metal nanoparticles. Magnetic nanoparticles used in the present invention can be prepared by conventional methods, for example, in Deng, H. et al. , Angew. Chem. Int. Ed. 2005 , 44 , 2782] can be produced and used by the method described. The magnetic nanoparticles are preferably used in an amount in the range of 0.1 to 100 moles, preferably 0.5 to 10 moles, based on 1 mole of the metal nanoparticles.

In the present invention, the magnetic nanoparticles are in the form of a metal oxide, and the metals included therein include Fe, Co, Ni, Mn, Pt, Cu, or Zn, and preferably Fe. It is also possible to use two or more kinds of magnetic nanoparticles, and the type of metal contained in the magnetic nanoparticles may be different.

The magnetic nanoparticles are preferably dispersed in ethanol, acetone, tetrahydrofuran or ethyl acetate, mixed with the metal nanoparticles, and reacted for about 5 minutes to 20 hours in a temperature range of 20 to 500 ° C.

Then, the sol-gelation reaction is performed by adding water to the mixture of the metal nanoparticles and the magnetic nanoparticles, wherein the amount of water used is 1 to 100 moles, preferably 2, based on 1 mole of the carrier precursor used. To 10 moles.

In the sol-gelation reaction, the reaction temperature is preferably 20 to 500 ° C., particularly 20 to 160 ° C., and the time required for completion of the reaction may vary depending on the reaction temperature and the molar ratio of the reactants used, but is 10 minutes to 20 hours. .

The sol-gelation reaction product can be filtered, washed with an appropriate solvent and dried to obtain a magnetic nanocatalyst that can be separated and reused with a magnet according to the present invention.

Acetone, tetrahydrofuran, ethyl acetate, diethyl ether, 1,4-dioxane, benzene, toluene, N , N -dimethylformamide, dimethyl sulfoxide, methanol, ethanol or chloroform may be used as the solvent. Preferred solvents are acetone or ethyl acetate.

The magnetic nanocatalyst according to the present invention has a specific surface area of about 50 to 1000 m ² g ⁻¹ , is a solid powder exhibiting superparamagnetism at room temperature, provides excellent reactivity in various organic reactions, and has magnetic properties. As shown in b), after the reaction, the separation and recovery can be easily performed by using an external magnet, and even if the recovered catalyst is recycled for several to several tens of times, there is no change in the excellent catalytic activity. In addition, it can be usefully used as a catalyst in various reactions such as oxidation of alcohol, hydrogenation, carbon-carbon coupling or alkylation.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the invention only.

<Production of Catalyst>

Example 1: Preparation of palladium-iron oxide nanocatalyst immobilized on aluminum hydroxide

(1-1): Preparation of Iron Oxide Nanoparticles

FeCl ₃ · 6H ₂ O (540 mg, 2.00 mmol) and ethylene glycol (16.0 g) were placed in a 100 mL reaction vessel equipped with a cooler and stirred at room temperature for 10 minutes. Subsequently, sodium acetate (1.60 g) and polyethylene glycol (400 mg, Mn = 400) were added to the reaction vessel and heated at 200 ° C. for 6 hours to form iron oxide nanoparticles. The reaction temperature was lowered to room temperature and the resulting solid was centrifuged and washed three times with ethanol (10 mL). The solid obtained was dried under reduced pressure to yield 182 mg of iron oxide nanoparticles having an average size of 100 nm. The manufacturing method of the iron oxide nanoparticles was referred to the reported data (Deng, H. et al. , Angew. Chem. Int. Ed. 2005 , 44 , 2782).

(1-2): Preparation of Palladium-Iron Oxide Nanocatalyst Immobilized on Aluminum Hydroxide

Palladium (II) acetate (115 mg, 0.512 mmol) and tetrahydrofuran (1.00 mL) were placed in a 50 mL reaction vessel and stirred for 10 minutes at room temperature and in air. Aluminum tri- sec -butoxide (4.00 g, 16.2 mmol) and 2-butanol (1.00 mL) were then added to the reaction vessel and heated at 50 ° C. for 20 minutes to form palladium nanoparticles. In the reactor, iron oxide nanoparticles (100 mg) obtained in (1-1) were dispersed in ethanol (2.00 mL) and added slowly and stirred at the same temperature for 10 minutes. Water (3.00 mL) was added to the reaction vessel and subsequently heated at the same temperature for 30 minutes. The reaction temperature was lowered to room temperature and the resulting solid was washed three times with acetone (10 mL), and then the obtained solid was dried at 120 ° C. for 5 hours to give 1.37 g of palladium-iron oxide nanocatalyst immobilized on aluminum hydroxide (Palladium content: 3.66%, iron content: 2.74%, specific surface area: 579 m ² g ^-1 ).

Test Example 1: Physical property test of palladium-iron oxide nanocatalyst immobilized on alumina hydroxide

A transmission electron microscope (TEM) photograph of the palladium-iron oxide nanocatalyst immobilized on aluminum hydroxide prepared in Example 1 is shown in FIG. 1. 1 (a) shows a form in which iron oxide nanoparticles having a size of 100 nm and palladium nanoparticles having a size of 3 nm are supported on aluminum hydroxide. (B) and (c) of FIG. 1 are enlarged iron oxide nanoparticles and palladium nanoparticles, respectively.

In addition, in order to confirm the magnetic properties of the palladium-iron oxide nanocatalyst immobilized on the aluminum hydroxide obtained above, it was measured by a superconducting quantum interference device (SQUID). As can be seen in Figure 2, it can be seen that the palladium-iron oxide nanocatalyst exhibits superparamagnetism at room temperature.

<Various organic reactions using palladium-iron oxide nanocatalyst immobilized on aluminum hydroxide>

Example 2

Epichlorohydrin (92 mg, 1.0 mmol) and the nanocatalyst (58 mg, 2.0 mol% palladium) prepared in Example 1 were placed in a reaction vessel, and ethyl acetate (2.0 mL) was added to the reaction vessel. As shown in 3 (a), the mixture was stirred for 4 hours under normal temperature and 1 atmosphere of hydrogen. Upon completion of the reaction, the catalyst was easily separated using an external magnet as shown in FIG. 3 (b). Then, after removing the solvent, the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to obtain 94 mg (> 99% yield) of the desired 1-chloro-2-propanol.

In the reaction, even if the catalyst was separated using an external magnet and reused 25 times, there was no difference in reactivity.

Examples 3 to 13

Similar to Example 2, various epoxy compounds were hydrogenolyzed as described in Table 1 below, and the yields in each reaction are shown in Table 1 below.

Example 14

Trans-Stilbene (180 mg, 1.00 mmol) and the palladium-iron oxide nanocatalyst prepared in Example 1 (58 mg, 2.0 mol% palladium) were added to a reaction vessel, ethyl acetate (2.0 mL) was added thereto, and room temperature, The mixture was stirred for 1 hour under 1 atmosphere of hydrogen. After separating the nanocatalyst using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to give 182 mg of the desired 1,2-diphenylethane ( 100% yield).

Example 15

Acetophenone (120 mg, 1.00 mmol) and the nanocatalyst (145 mg, 5.0 mol% palladium) prepared in Example 1 were placed in a reaction vessel, followed by addition of ethyl acetate (2.0 mL) and hydrogen at room temperature and 1 atmosphere of hydrogen. The mixture was stirred for 10 hours. After separating the nanocatalyst by using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to give 114 mg (93% yield) of the desired phenylethyl alcohol. Got.

Example 16

Phenylethyl alcohol (122 mg, 1.00 mmol) and the nanocatalyst (145 mg, 5.0 mol% palladium) prepared in Example 1 were added to the reaction vessel, toluene (2.0 mL) was added thereto, and then at room temperature and 1 atmosphere of oxygen. The mixture was stirred for 12 hours. After separating the nanocatalyst by using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to obtain 120 mg (> 99% yield) of the desired acetophenone. Got.

Example 17

Benzyl alcohol (108 mg, 1.00 mmol) and the nanocatalyst (58 mg, 2.0 mol% palladium) prepared in Example 1 were added to the reaction vessel, and then heptane (5.0 mL) was added thereto at 90 ° C. under 1 atmosphere of oxygen. The mixture was stirred for 20 hours. After separating the nanocatalyst using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to obtain the desired N -benzylidine-2-phenethylamine. 188 mg (90% yield) was obtained.

Example 18

Acetophenone (120 mg, 1.00 mmol) and the nanocatalyst (58 mg, 2.0 mol% palladium) prepared in Example 1 were added to the reaction vessel, followed by addition of potassium phosphate (636 mg) and toluene (5.0 mL). The mixture was stirred for 5 h under argon. After separating the nanocatalyst using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to obtain the desired 1,3-diphenylpropane-1- 197 mg (94% yield) was obtained.

Example 19

2-nitrobenzyl alcohol (154 mg, 1.00 mmol) and the nanocatalyst prepared in Example 1 (58 mg, 2.0 mol% palladium) were added to a reaction vessel, and then toluene (5.00 mL) was added thereto. Stir under hydrogen for 4 hours. Acetophenone (144 mg, 1.20 mmol) and potassium phosphate (636 mg) were added to the reaction mixture, and the mixture was stirred at 110 ° C. under argon for 10 hours. After separating the nanocatalyst by using an external magnet, the solvent was removed, and then the obtained residue was passed through a silica gel column (eluent: hexane / ethyl acetate (10/1)) to obtain 176 mg (86% yield) of the desired 2-phenylquinoline. )

As described above, the magnetic nanocatalyst of the present invention is a nano-sized transition metal particles and magnetic nanoparticles are bonded to the carrier, providing excellent reactivity when used as a catalyst in the organic reaction, and easily separated by a magnet after the reaction It can be recovered, and the recovered catalyst can be recycled without changing its activity, so it can be usefully used as a catalyst in various reactions such as ring opening reaction of epoxy compound, oxidation reaction of alcohol, hydrogenation reaction, carbon-carbon coupling reaction, alkylation reaction, etc. Can be.

Claims (15)

A magnetic nanocatalyst in which a transition metal nanoparticle and an oxide of Fe are supported on a carrier. The method of claim 1, The transition metal nanoparticles have a particle size range of 1 to 100 nm, and the oxide of Fe has a particle size range of 1 to 500 nm, magnetic nanocatalyst. The method of claim 1, Magnetic oxide catalyst, characterized in that the transition metal nanoparticles and the oxide of Fe is supported in a ratio of 1: 0.1 to 100. The method of claim 1, Magnetic nanoparticles, characterized in that the transition metal is selected from Pd, Pt, Ru, Os, Rh, Ir, Re, Mo, W, Cu, Ag, Au, Zn, Hf, Ta, Nb, V and combinations thereof catalyst. The method of claim 4, wherein Magnetic transition nanocatalyst, characterized in that the transition metal is Pd. delete delete The method of claim 1, Magnetic carrier nanocatalyst, characterized in that the carrier is selected from silica, titania, alumina, zirconia, magnesia and combinations thereof. (1) mixing and heating a transition metal complex, a metal grasp ligand and a carrier precursor to form a transition metal nanoparticle, and then mixing the resulting transition metal nanoparticle with an oxide of Fe; And (2) A method for producing the magnetic nanocatalyst of claim 1, which comprises sol-gel reaction by adding water to the resulting mixture. The method of claim 9, The transition metal complex is hydride (H ^-), chloride (Cl ^-), cyanide (CN ^-), acetyl (CH ₃ CO ^-), triphenylphosphine _{(P (C 6 H 5)} 3), dibenzyl Lidenacetone (C ₆ H ₅ CH = CHCOCH = CHC ₆ H ₅ ), carbonyl (CO) and diene (CH ₂ CHCHCH ₂ ), characterized in that it comprises a ligand selected from, magnetic nanocatalyst manufacturing method. The method of claim 9, The metal-catalyzed ligand is an organic acid (C _n COOH, C _n : hydrocarbon, 7 ≦ _n ≦ 30), an organic amine (C _n NH ₂ , C _n : hydrocarbon, 7 ≦ _n ≦ 30), alkane thiol (C _n SH, C _n : hydrocarbon, 7 ≦ _n ≦ 30), phosphine (C _n P, C _n : hydrocarbon, 7 ≦ _n ≦ 30) and polyethylene glycol, characterized in that the method for producing a magnetic nanocatalyst. The method of claim 9, The carrier precursor is tetraalkyl orthosilicate (Si (OR) ₄ ), titanium tetraalkoxide (Ti (OR) ₄ ), aluminum trialkoxide (Al (OR) ₃ ), zirconium alkoxide (Zr (OR) ₄ ), magnesium Alkoxide (Mg (OR) ₂ ), wherein R is a methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl or s-butyl group, and mixtures thereof Method for producing a magnetic nanocatalyst. The method of claim 9, The metal-catch ligand and the carrier precursor are used in an amount ranging from 10 to 1000 moles based on 1 mole of the transition metal complex, respectively. The method of claim 9, The method of producing a magnetic nanocatalyst, characterized in that the oxide of Fe is used in an amount ranging from 0.1 to 100 moles based on 1 mole of transition metal nanoparticles. The method of claim 9, The Fe oxide is mixed with the transition metal nanoparticles in a temperature range of 20 to 500 ℃, method of producing a magnetic nanocatalyst.

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