KR20200142731A - Heteroleptic Fe Complex Catalyst And Preparing Method Of Cyclic Carbonates Using Fe Complex - Google Patents

Abstract

The present invention relates to a heteroleptic iron complex catalyst represented by any one of chemical formula (1) of [Fe(BIP^R)(dhbpy)X]X, chemical formula (2) of [Fe(tpy)(bpy)X]X and chemical formula (3) of [Fe(tpy)(dhbpy)X], and including any one co-catalyst selected from TBAB, TBAI, TPPI and TBD-HI as an additive, wherein BIP is disubstituted-2,6-bisiminopyridine, tpy is terpyridine, bpy is bipyridine, dhbpy is dihydroxybipyridine, R represents EtOH, PrOH, Pr(OH)2 or PrIm (propyl-1H-imidazole), X represents Cl, Br or I, TBAB is tetrabutylammonium bromide, TBAI is tetrabutylammonium iodide, TPPI is tetraphenylphosphonium iodide, and TBD is 1,5,7-triazabicyclo[4,4,0]dec-5-ene.

Description

Heteroleptic Fe Complex Catalyst And Preparing Method Of Cyclic Carbonates Using Fe Complex}

The present invention relates to a hetero-ligand iron complex catalyst and a method for producing a cyclic carbonate using the catalyst. A cocatalyst providing a nucleophilic halide ion is added, and it is effective in the yield and selectivity of the cyclic carbonate under mild conditions.

Investigating chemical reactions that can recycle CO ₂ as a chemical raw material for the production of industrially attractive chemicals, plastic precursors and fuels is considered a practical way to contribute to reducing the total amount of anthropogenic CO ₂ released into the atmosphere. come.

Synthesis of cyclic carbonates by the addition of epoxides represents one of several processes using CO ₂ , and this reaction is thermodynamically preferred because the ring-opening of the epoxide releases the ring-transformation energy.

In addition, the efficient transformation of the carbon dioxide (CO ₂ ) into useful compounds such as formic acid, methanol, ureas, carboxylates, polycarbonates and polyurethanes is the potential for CO ₂ to be in organic synthesis. It is very attractive because it is an inexpensive and abundant C1 building block.

Among these compounds, cyclic carbonates produced by cycloaddition of CO ₂ to epoxides are attractive chemicals.

These compounds are commonly used as electrolyte components, polar aprotic solvents, and chemical intermediates in lithium-ion batteries. Typically, these compounds are synthesized using toxic and dangerous reagents such as phosgene.

Therefore, the demand for the efficient catalyst for the conversion of carbon dioxide is increasing. Various metal-based catalysts have shown activity for the coupling of epoxides to carbon dioxide.

In catalyst systems for cyclic carbonate synthesis, Lewis acidic compounds such as metal-organic complexes or hydrogen bond donors activate the epoxide ring opening with a significant acceleration of the reaction rate. At the same time, the quaternary ammonium or phosphonium salt and the nucleophilic counter anion in the ionic liquid advance the epoxide ring opening by nucleophilic attack.

Following the cooperative step of ring-opening, CO ₂ provides an alkoxy carbonate intermediate in which cyclization yields a cyclic carbonate product by inserting a metal alkoxide bond. Consequently, most catalysts for the cycloaddition of carbon dioxide to epoxides have been known as binary systems consisting of Lewis acids ("catalyst") and nucleophilic components ("cocatalyst").

Until now, metalosalen complexes of Al, Cr, Mn, Co, or Zn are fundamental characteristics of salen-ligands, namely the ease of reaction, the possibility of chelation by most metal ions, and the axial direction. Much attention has been drawn to the planar geometry with empty space for epoxide activation.

On the other hand, the use of a metal-free system has also been extensively studied, and currently commercially used cyclic carbonate synthesis catalysts are hydrogen bond donors having quaternary ammonium or phosphonium (R-OH, R-NH ₂ and their protons It is based on salts.

However, since systems using organic substances require high temperature and high concentration of substrates, continuous research has been conducted on metal-based systems showing strong Lewis acidity in order to carry out the reaction under milder conditions. In recent years, Lewis acidity and nucleophilicity The study of multifunctional single component catalysts showing all components has been considered a sustainable approach to CO2 conversion under mild conditions.

As for the metal-based single component catalyst, a widely developed method is to introduce a nucleophilic component as a quaternary onium salt linked to a ligand. Bifunctional Al (salen), Co (salen) and Zn (salpyr) complexes with ammonium or pyridinium halides have been reported to be more active compared to the binary catalyst analogs. Metalporphyrins of Mg and Zn with ammonium bromide, phosphonium bromide or imidazolium bromide are also developed to show higher catalytic activity without any cocatalyst. Became.

In addition, in the bisimidazole-functionalized cobalt-porphyrin system, imidazole attacked the metal center, thereby promoting the dissociation of the nucleophilic chloride coordinated to the metal. As a neutral nucleophile, the tertiary aliphatic amine of the N-methylhomopiperazine residue was designed to be introduced into the Al (salen)-based ligand to directly attack the epoxide.

A synergistic effect was observed when multiple sites for epoxide activation were introduced. Various hydrogen bond donors, such as phenolic hydroxyl groups, N-H groups, and protonated tertiary ammonium groups, have been involved in supplying additional Bronsted acid components and improving catalyst performance.

Studies related to hydrogen bond donors have been developed in depth in organic catalyst systems, but the application of metal-ligand complexes has rarely been studied. In addition, despite the growing interest in iron catalysts, there have been few reports of functionalized iron-ligand systems for a sustainable, carbon-balanced approach to carbon dioxide conversion worth the challenge.

The use of a multifunctional and sustainable Fe catalyst in the present invention is an invention for a catalyst that forms cyclic carbonates from epoxides and carbon dioxide even under mild conditions of 50°C and 5 bar pressure. In the present invention, a halide counter anion and a hydrogen bond donor for activating epoxide ring opening are provided for an optimal catalyst, and a cocatalyst and a single component catalyst system are provided.

An object of the present invention is to prepare a multifunctional catalyst by introducing heterologous ligands having various functional groups to the iron core metal, and as a catalyst for the cyclic addition reaction of CO ₂ and epoxide together with a cocatalyst that provides additional nucleophilic halide ions. It is to provide a method for preparing a cyclic carbonate compound by using.

In order to solve the above problems, the present invention is a heterogeneous ligand iron complex catalyst of any one of the following formulas (1) to (3), wherein any one of TBAB, TBAI, TPPI, and TBD-HI is additionally configured as an additive. Provides.

Formula (1)

[Fe(BIP ^R )(dhbpy)X]X

Formula (2)

[Fe(tpy)(bpy)X]X

Formula (3)

[Fe(tpy)(dhbpy)X]

here,

BIP = disubstituted-2,6-bisiminopyridine

tpy = terpyridine, bpy = bipyridine, dhbpy = dihydroxybipyridine

R = EtOH, PrOH, Pr(OH) ₂ ,PrIm(propyl-1 H -imidazole)

X = Cl, Br, I

TBAB = tetrabutylammonium bromide

TBAI = tetrabutylammonium iodide

TPPI = tetraphenylphosphonium iodide

TBD = 1,5,7-triazabicyclo[4,4,0]dec-5-ene

In addition, the present invention provides a method for producing a cyclic carbonate having 3 to 4 carbon atoms by a cyclization addition reaction of a mono- or di-substituted oxide and CO ₂ under a hetero-ligand iron complex catalyst.

In addition, in the present invention, the monosubstituted oxide is styrene oxide, para chloro styrene oxide, p-bromo oxide, alkyl or alkylene oxide having 1 to 10 carbon atoms. , Glycidol (phenyl glycidyl ether), allyl glycidyl ether (Allyl glycidyl ether), methacrylate oxide (methacrylate oxide), chloromethyl oxide (chloromethyl oxide) It provides a method for producing cyclic carbonates.

In addition, the present invention provides a method for producing cyclic carbonates characterized in that the disubstituted oxide is cyclopentene oxide or cyclohexene oxide.

The present invention secures a uniform organometallic catalyst technology for CO ₂ conversion using a multifunctional catalyst in which heterogeneous ligands having various functional groups are introduced into the iron core metal and a cocatalyst providing nucleophilic halide ions, It is efficient in the production method of high value-added carbon compounds.

1 is a description of the function and chemical structure of the ligand for the heterogeneous Fe-bisiminopyridine complex of the present invention.
Figure 2 is (a) a predicted structure of a heterogeneous Fe-bisiminopyridine complex [Fe(BIP ^R )(dhbpy)I]I coupled with an epoxide coordination, (b) a heterogeneous Fe-bisiminopyridine complex and a cocatalyst It is a diagram illustrating the mechanism of a method for producing cyclic carbonates using a heterogeneous iron complex catalyst composed of.

Hereinafter, preferred embodiments of the present invention will be described in detail. First, in describing the present invention, detailed descriptions of related known functions or configurations are omitted so as not to obscure the subject matter of the present invention.

The terms'about','substantially', etc. of the degree used in the present specification are used at or close to the numerical value when manufacturing and material tolerances specific to the stated meaning are presented, and are used in the sense of the present invention. To assist, accurate or absolute figures are used to prevent unfair use of the stated disclosure by unscrupulous infringers.

The present invention relates to a hetero-ligand iron complex catalyst of any one of the following formulas (1) to (3), wherein any one of TBAB, TBAI, TPPI, and TBD-HI is further composed of an additive,

The present invention relates to the development of a technology for producing a high value-added carbon compound using a carbon raw material used as a resource and securing a homogeneous organometallic catalyst technology for CO ₂ conversion by using a multifunctional catalyst, which is a catalyst of the present invention, by introducing a ligand having various functional groups to the iron core metal .

Formula (1)

[Fe(BIP ^R )(dhbpy)X]X

Formula (2)

[Fe(tpy)(bpy)X]X

Formula (3)

[Fe(tpy)(dhbpy)X]

here,

BIP = disubstituted-2,6-bisiminopyridine

tpy = terpyridine, bpy = bipyridine, dhbpy = dihydroxybipyridine

R = PrOH, Pr(OH) ₂ ,PrIm(propyl-1 H -imidazole)

X = Cl, Br, I

TBAB = tetrabutylammonium bromide

TBAI = tetrabutylammonium iodide

TPPI = tetraphenylphosphonium iodide

TBD = 1,5,7-triazabicyclo[4,4,0]dec-5-ene

1 is a description of the function and chemical structure of the ligand for the heterogeneous Fe-bisiminopyridine complex of the present invention. In particular, the heterogeneous Fe-bisiminopyridine complex is characterized in that it has a hydrogen bond donor (HBD) and a functionalized ligand of a nucleophilic activator.

The method of preparing the catalyst is as shown in Reaction Formulas (1) to (3) below.

Scheme (1)

Scheme (2)

Scheme (3)

First, the present invention is iminopyridine functionalized by the condensation reaction of 2-pyridinecarboxaldehyde (picolinealdehyde) or 2,6-pyridinedicarboxaldehyde (2,6-pyridinedicarboxaldehyde) with an amine. , IP) or bisiminopyridine (BIP) ligand is prepared.

The following scheme (4) is an example of a method for preparing a bisiminopyridine (BIP) ligand.

Scheme (4)

Here, the types of H ₂ NR are as follows.

Heteroleptic ligand iron catalysts of Schemes (1) to (3) are synthesized by sequentially introducing each ligand.

Scheme (1) is a bisiminopyridine (BIP) ligand produced by the condensation reaction of 2,6-pyridinedicarboxaldehyde (2,6-pyridinedicarboxaldehyde) and a primary amine (RNH ₂ ) FeX ₃ (X = Cl, Br , I) After reacting with, further reacting with dihydroxybipyridine (dhbpy) and LiX,

Scheme (2) or (3) is by the reaction of terpyridine (tpy) and FeX ₃ The intermediate product Fe(tpy)X ₃ (X = Cl, Br, I) is characterized by an additional reaction with bipyridine (bpy) or dihydroxybipyridine (dhbpy).

After selectively introducing one tridentate ligand (terpyridine or bisiminopyridine), a dihydroxybipyridine (dhbpy) ligand is complexed to form an axial halide, allowing a halide nucleophile that can dissociate from the Lewis acid iron center.

The following is a mono- or di-substituted cyclic carbonate comprising preparing a cyclic carbonate having 3 to 4 carbon atoms by cyclization addition reaction of a mono- or di-substituted oxide and CO ₂ using the iron complex catalyst of the present invention. It is a description of the manufacturing method of Ryu.

Table 1 is a heterogeneous Fe-bisiminopyridine complex (heteroleptic Fe-bisiminopyridine complexes) or a heterogeneous Fe complex catalyst (Fe(II)cat.) of any one of Formulas (1) to (3), and

The present invention relates to a method for preparing mono-substituted cyclic carbonates of styrene oxide using a hetero-ligand iron complex catalyst composed of any one of TBAB, TBAI, TPPI, and TBD-HI.

BIP = disubstituted-2,6-bisiminopyridine

tpy = terpyridine, bpy = bipyridine, dhbpy = dihydroxybipyridine

R = EtOH, PrOH, Pr(OH) ₂ ,PrIm(im(propyl-1 H -imidazole))

X = Cl, Br, I

TBAB = tetrabutylammonium bromide

TBAI = tetrabutylammonium iodide

TPPI = tetraphenylphosphonium iodide

TBD = 1,5,7-triazabicyclo[4,4,0]dec-5-ene

Styrene oxide (1a), which is a base material (reactant), is an optimal material in consideration of the amount of catalyst, cocatalyst, and temperature under an optimized iron complex catalyst and a solvent-free condition under a cocatalyst. Using the styrene oxide (1a) as a reaction condition, an unfunctionalized Fe catalyst ([Fe(tpy)(bpy)Br]Br, 0.25 mol%) and a cocatalyst TBAB (0.5 mol) at 60° C. and 5 bar CO ₂ pressure %), the yield is 20% for the synthesis of cyclic carbonates (item 1).

The dhbpy ligand, which introduced a hydroxy group (OH), which is two hydrogen bond donors, to a bidentate bpy ligand has a remarkably improved reactivity and an efficient reaction with a yield of 78% (item 2). The exchange of the halogen ligand from bromine (Br) to chlorine (Cl) reduced the yield of cyclic carbonate (2a) to 49%, due to the dissociation rate of the axial halide at 60°C (item 3).

It is converted from terpyridine to bisiminopyridine, a tridentate ligand that can be easily modified through an imino alkyl chain, and an additional hydrogen bond donor (EtOH, PrOH, Pr(OH) ₂ ) is introduced. Became (items 4-6).

In items 4 to 6, the reactivity was compared in the iron-ligand complex containing several monohydroxy and dihydroxy groups and the cocatalyst TBAB, and [Fe(BIPPr ^OH )(dhbpy)Br]Br was reacted with a yield of 85%. It can be seen that it is efficient (item 6). When the role of halide in various positions such as ligand, counterion and cocatalyst is investigated, [Fe(BIPPr ^OH )(dhbpy)Br]Br cocatalyst TBAI item 7 has better efficiency than item 6 In addition, the Fe complex ([Fe(BIPPr ^OH )(dhbpy)I]BI) containing iodide (I) has the greatest efficiency in reactivity, possibly due to the dissociation rate of the axial halide and the nucleophilicity of the free halide. (Item 8).

However, the [Fe(BIP ^PrOH )(dhbpy)Br]Br complex is somewhat hygroscopic and has a disadvantage that may cause problems in manufacturing and reproducibility.

Therefore, a ligand BIP ^PrIm containing an imidazole group as a carbon dioxide activator was synthesized, and [Fe(BIP ^PrIm )(dhbpy)I]I is the optimal complexing agent with 94% yield of the product cyclic carbonate (2a) (item 10). ~12).

Various ammonium, phosphonium, and guanidinium salts were tested to investigate the effect of the cocatalyst on this reaction, and the iodide nucleophile, TPPI (tetraphenylphosphonium iodide), showed the greatest reactivity, giving a 99% yield ( Item 11).

Although the [Fe(BIPPrIm)(dhbpy)I] catalyst of item 11 showed that the amount of catalyst can be reduced from 0.25 mol% to 0.1 mol% in the final optimized condition (item 13), the further 50°C It can be seen that the yield was excellent at 82% even in the 1.0 mol% TPPI cocatalyst (item 14) at a low reaction temperature.

In control experiments (items 15-17), individual components (FeI ₂ , BIP ^PrIm , dhbpy) showed little catalytic activity, and treatment with a physical mixture of FeI ₂ and a ligand first incorporated multifunctional groups around the ferrous metal center. You can see that it is important to do

Next, Table 2 shows the types of mono-substituted cyclic carbonates produced by reacting with heterogeneous Fe complex catalysts and cocatalysts suitable for oxides having various mono- or di-substituent groups.

^a DMF (10M), 80℃

^b [Fe(BIP ^PrIm )(dhbpy)I]I (0.5 mol %), DMF (10 M), CO ₂ (10 bar), 100℃

^c [Fe(BIP ^PrIm )(dhbpy)I]I (0.5 mol %), MeCN (10 M), CO ₂ (10 bar), 100℃

^d [Fe(BIP ^PrIm )(dhbpy)I]I (0.5 mol %), DMF (10 M), CO ₂ (10 bar), 100℃

The catalyst and cocatalyst of the determined optimized conditions were used to react with various mono- or di-substituted epoxides and carbon dioxide, and the catalyst applicability of the functionalized Fe composite was confirmed. Aryl and alkyl substituted epoxides can be found to be effective substrates providing the corresponding cyclic carbonates 2a-d in moderate to good yields.

Epoxides containing long alkyl chains (1e-g) have reduced reactivity, possibly due to heterogeneity under simple conditions, and polar solvents (DMF) and elevated temperatures (80°C and 60°C) provide their quantitative conversion. Was necessary. Epoxides containing chain alkyl epoxides, hydroxymethyl and their derivatives (1h-k) can yield 76 to 93% of the corresponding cyclic carbonates.

It should be noted that even if the epoxide 1k having a methacrylate group is polymerized at a temperature of 80° C. or higher, the cyclization reaction proceeds well under mild conditions, so that a desired product having the original ester and olefin units can be obtained.

With chloromethyloxirane (1L), it was observed that the substitution reaction of alkyl chloride by various halide components or participation of adjacent groups did not occur in the present system.

The internal epoxide was regarded as a difficult substrate due to steric constraints, and intense conditions such as a CO2 pressure of 10 bar and a high temperature of 100°C were required under solvents such as MeCN (10M) and DMF (10M). The selectivity for cyclic carbonates in Table 2 were all at least 99%, reflecting the absence of polymers and any other by-products such as diols.

^a 50 mmol of 1a , 80°C, 24h.

Table 3 shows that in order to utilize the catalytic performance of [Fe(BIP ^PrIm )(dhbpy)I]I, the catalyst/substrate (epoxide) ratio is gradually reduced under 10 bar CO ₂ pressure. A relatively high value was obtained in TON with 0.050 mol% catalyst under mild conditions at 60°C, and the Fe complex of this functional group showed high catalytic activity even in 50 mmol scale styrene oxide 1a (item 4).

Figure 2 is (a) a predicted structure of a heterogeneous Fe-bisiminopyridine complex [Fe(BIP ^R )(dhbpy)I]I to which an epoxide is coordinated, (b) a heterogeneous Fe-bisiminopyridine of the present invention It is an explanatory diagram of the mechanism of a method for producing cyclic carbonates using a heterogeneous iron complex catalyst composed of a complex and a cocatalyst.

Density functional theory (DFT) is one of the theories for calculating the shape and energy of electrons in substances and molecules.

DFT calculations were performed to analyze the molecular structure of the theoretical reaction complex and to demonstrate the feasibility of a functionalized iron-ligand system.

The proposed structure of the epoxide-coordinated Fe complex is shown in Fig. 2(a) in which iodide in the [Fe(BIP ^PrIm )(dhbpy)I] complex is dissociated and the Lewis acid iron center activates the epoxide. The most characteristic feature of the structure optimized for the pre-reaction complex is the presence of hydrogen bonds of OH and O between the hydroxy group of the bipyridine ligand and the epoxide coordinated to iron.

This is because iodide, which promotes epoxide ring opening, is preferred for nucleophilic attack. In addition, the carbon dioxide molecule is located near the Lewis basic imidazole group and the epoxide, so that carbon dioxide injection and the formation of a haloalkoxy carbonate intermediate are more feasible. This preliminary reaction model suggests that although the distance between imidazole and carbon dioxide is rather large, it still allows interaction under a reaction system with a carbon dioxide pressure of 3 to 5 bar.

The present invention can suggest a possible reaction route as shown in Fig. 2(b). The activity pattern of the multifunctional Fe catalyst can be rationalized through a hydrogen bond donor, Lewis basic CO ₂ activator and Lewis acidic iron center. After dissociation of the imino or iodine ligand, the epoxide is activated by the Lewis acidic center and the hydroxy group of the ligand, promoting epoxide ring opening by nucleophilic attack of the halide. Activation of adjacent CO ₂ by Lewis basic imidazole groups promotes the transfer of CO _{2 to} the halo alkoxy anionic species to form a halo alkoxy carbonate intermediate. The intramolecular substitution releases the 5 membered CO ₂ circulating load and recovers the Fe catalyst and halides required for the catalyst system.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible within the scope of the technical spirit of the present invention. It will be obvious to those who have the knowledge of

Claims (4)

TBAB, TBAI, TPPI, TBD-HI any one of the following formulas (1) to (3) of the following formula (1) to (3) further configured as an additive in any one of the cocatalyst is a heterogeneous ligand iron complex catalyst.

Formula (1)
[Fe(BIP ^R )(dhbpy)X]X
Formula (2)
[Fe(tpy)(bpy)X]X
Formula (3)
[Fe(tpy)(dhbpy)X]
here,
BIP = disubstituted-2,6-bisiminopyridine
tpy = terpyridine, bpy = bipyridine, dhbpy = dihydroxybipyridine
R = EtOH, PrOH, Pr(OH) ₂ ,PrIm(propyl-1 H -imidazole)
X = Cl, Br, I
TBAB = tetrabutylammonium bromide
TBAI = tetrabutylammonium iodide
TPPI = tetraphenylphosphonium iodide
TBD = 1,5,7-triazabicyclo[4,4,0]dec-5-ene Under the hetero-ligand iron complex catalyst of claim 1,
A method for producing a cyclic carbonate having 3 to 4 carbon atoms by a cyclization addition reaction of a mono- or di-substituted oxide and CO ₂ .
The method of claim 2,
The mono-substituent oxide is styrene oxide, para chloro styrene oxide (p-chloro oxide), para bromo styrene oxide (p-bromo oxide), alkyl or alkylene oxide having 1 to 10 carbon atoms, and glycidol. Cyclic carbonates characterized by being (glycidol), phenyl glycidyl ether, allyl glycidyl ether, methacrylate oxide, and chloromethyl oxide Manufacturing method.
The method of claim 2,
The bi-substituent oxide is a cyclopentene oxide (cyclopentene oxide) or a cyclohexene oxide (cyclohexene oxide) characterized in that the cyclic carbonate production method.

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