Dialkylaluminum halide complexes, their production methods, and utilization.

Abstract

To provide a novel complex formed from a dialkyl aluminum halide and a nitrogen-containing organic compound and to provide a method for producing the same and use thereof.SOLUTION: There is provided a complex formed from a dialkyl aluminum halide and a nitrogen-containing organic compound, wherein the bond distance between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of the dialkyl aluminum halide located at the shortest distance to the nitrogen atom is less than 3.4 Å.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention provides a novel complex formed from a dialkylaluminum halide and a nitrogen-containing organic compound, a method for producing the same, and its use.

Background Art

[0002] Aluminum halide (AlX3, X = F, Cl, Br, I) is a Lewis acid and forms a charge-separated complex by reacting with a Lewis base compound. This complex has industrial value as a catalyst for organic reactions, an electrolyte, an ionic liquid, etc. The reaction between aluminum halide and a Lewis base compound is generally an equimolar reaction, and the reaction proceeds rapidly. However, it is known that the composition and chemical properties of the complex vary greatly depending on factors such as the stoichiometric ratio of the Lewis acid or Lewis base compound, the strength of the coordination ability, and the molecular structure. For example, complexes composed of AlCl3, pyridine (Py), and pyridine derivatives are reported to be solids (P. Pullmann, et.al, Z. Naturforsch. 1982, 37B, 1312-1315) or liquids (Y. Fang, et.al, Electrochim. Acta, 2015, 160, 82-88) depending on the stoichiometric ratio of AlCl3.

[0003] On the other hand, an alkylaluminum halide (RnAlX) in which part of the X of AlCl3 is substituted with an alkyl group (3-n), R=Me, X=Cl, Br, n=1 or 2) is also a Lewis acid and exhibits similar reactivity to the above reaction. As a prior example, it has been found that when Me2AlBr is reacted with a sterically bulky Lewis base (triethylamine, Et3N), an equimolar complex ([Me2AlBr·NEt]) is formed, while when it is reacted with a sterically bulky primary amine (isobutylamine, iBu-NH2), two amines are added to obtain [Me2Al(H2N-iBu)2]Br (Atwood, DA et.al, Inorg. Chem. 1997, 36, 2034-2039). From these reports, it is understood that the composition and chemical properties of the complex are strongly influenced by the coordination space around aluminum.

[0004] Alkylaluminum halide (RnAlX (3-n) There are few reported cases of complexes of alkylaluminum (X=Cl, Br, n=1 or 2) and Lewis bases, and it remains an unexplored area academically. This is because (1) they are spontaneously combustible and (2) they react rapidly with moisture in the air, making analysis extremely difficult. In particular, complexes consisting of alkylaluminum halides and Lewis bases have mostly been reported as adducts, without distinction of state (solid, liquid) or clarity of composition. Furthermore, no chemical utility (catalyst or important intermediate product, etc.) of these complexes has been found. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] P. Pullmann, et.al, Z. Naturforsch. 1982, 37B, 1312-1315 [Non-Patent Document 2] Y. Fang, et.al, Electrochim. Acta, 2015, 160, 82-88 [Non-Patent Document 3] Atwood, DA et.al, Inorg. Chem. 1997, 36, 2034-2039 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] This invention provides a completely novel complex formed from a dialkylaluminum halide and a nitrogen-containing organic compound, which has not been previously known, as well as a method for producing the same and its uses. [Means for solving the problem]

[0007] The inventors discovered that when dialkylaluminum chloride is dissolved in a hydrocarbon solvent and a predetermined nitrogen-containing organic compound is added, an insoluble, isolateable complex precipitates and separates from the solvent. ¹H-NMR analysis confirmed that the complex is formed from the dialkylaluminum chloride and the nitrogen-containing organic compound in a molar ratio of 2:1. Remarkably, it was found that by adding a metal catalyst such as an aluminum-magnesium alloy to this complex, trialkylaluminum, an important substance used in polymerization co-catalysts and the production of organic semiconductor materials, can be produced very efficiently.

[0008] Therefore, this application encompasses the following inventions. (1) A complex formed from a dialkylaluminum halide and a nitrogen-containing organic compound, wherein the bond distance between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of the dialkylaluminum halide located at the shortest distance to the nitrogen atom is less than 3.4 Å. (2) The complex according to (1), characterized in that the bond distance between the nitrogen atom and the aluminum atom of the complex is in the range of 2.0 to 2.2 Å. (3) The complex according to (1) or (2), wherein the nitrogen-containing organic compound is a conjugated heterocyclic compound containing at least one nitrogen atom and having a five-membered ring and / or six-membered ring skeleton. (4) The complex according to any one of (1) to (3), wherein the conjugated heterocyclic compound is selected from the group consisting of pyridine, 2,6-dimethylpyridine, 2,4,6-trimethylpyridine, 2,6-diethylpyridine, 2,6-diisopropylpyridine, 2-methylpyridine, 4-methylpyridine, quinoline, isoquinoline, o-bipyridine, and 1-methylimidazole. (5) The complex according to any one of (1) to (4), wherein one or both alkyl groups of the dialkylaluminum halide are methyl groups. (6) The complex according to any one of (1) to (5), wherein the halogen of the dialkylaluminum halide is a chloride. (7) A method for forming a complex from the dialkylaluminum halide and the nitrogen-containing organic compound by mixing them in an organic solvent. (8) The method according to (7), wherein the complex is isolated as an insoluble fraction in the organic solvent. (9) The method according to (7) or (8), wherein the nitrogen-containing organic compound is a conjugated heterocyclic compound having a five-membered ring and / or a six-membered ring skeleton and containing at least one nitrogen atom. (10) The method according to any one of (7) to (9), wherein the conjugated heterocyclic compound is selected from the group consisting of pyridine, 2,6-dimethylpyridine, 2,4,6-trimethylpyridine, 2,6-diethylpyridine, 2,6-diisopropylpyridine, 2-methylpyridine, 4-methylpyridine, quinoline, isoquinoline, o-bipyridine, and 1-methylimidazole. (11) The method according to any one of (7) to (10), wherein one or both alkyl groups of the dialkylaluminum halide are methyl groups. (12) The method according to any one of (7) to (11), wherein the halogen of the dialkylaluminum halide is a chloride. (13) The method according to any one of (7) to (12), wherein the organic solvent is a hydrocarbon solvent. (14) The method according to any one of (7) to (13), wherein the hydrocarbon solvent is at least one selected from the group consisting of saturated hydrocarbon solvents having 4 to 18 carbon atoms and aromatic hydrocarbon solvents having 6 to 12 carbon atoms. (15) The method according to any one of (7) to (14), wherein the hydrocarbon solvent is n-dodecane. (16) A preparation for use in the production of trialkylaluminum, containing the complex according to any one of (1) to (6). (17) A method for producing trialkylaluminum using the complex according to any one of (1) to (6).

Advantages of the Invention

[0009] The conventional methods for producing trialkylaluminum had problems to be solved not only in terms of safety but also in terms of cost and the number of steps. By providing the novel complex according to the present invention, it becomes possible to produce trialkylaluminum safer and more efficiently than, for example, the conventionally known methods.

Brief Description of the Drawings

[0010] [Figure 1] Conversion of TMAL by DMAC·pyridine complex. [Figure 2] Conversion of TMAL by DMAC·2,6-tert-butylpyridine complex. ​​​​​​​​​​​​​Examples of dialkylaluminum halides of the present invention include, but are not limited to, dimethylaluminum chloride, diethylaluminum chloride, dipropylaluminum chloride, diisopropylaluminum chloride, dibutylaluminum chloride, diisobutylaluminum chloride, methylethylaluminum chloride, dimethylaluminum fluoride, diethylaluminum fluoride, dipropylaluminum fluoride, diisopropylaluminum fluoride, dibutylaluminum fluoride, diisobutylaluminum fluoride, methylethylaluminum fluoride, dimethylaluminum bromide, diethylaluminum bromide, dipropylaluminum bromide, diisopropylaluminum bromide, dibutylaluminum bromide, diisobutylaluminum bromide, methylethylaluminum bromide, dimethylaluminum iodide, diethylaluminum iodide, dipropylaluminum iodide, diisopropylaluminum iodide, dibutylaluminum iodide, diisobutylaluminum iodide, and methylethylaluminum iodide. Dimethylaluminum chloride is particularly preferred in the present invention.

[0013] The nitrogen-containing organic compounds useful in the present invention can form complexes with dialkylaluminum halides, satisfying the condition that the bond distance (N-Al distance) between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of the dialkylaluminum halide located at the shortest distance to that nitrogen atom is less than 3.4 Å. As particularly confirmed in the examples of this application, this N-Al distance is preferably a maximum of 2.2 Å, and more preferably in the range of 2.0 to 2.2 Å. Theoretically, if this bond distance is less than 3.4 Å, the nitrogen-containing organic compound can form a complex with a dialkylaluminum halide, and as a result, the formed complex can be effectively utilized for the efficient conversion of DMAC to TMAL.

[0014] The above N-Al distance can be calculated as the bond distance between the N atom (Lewis basicity) and the Al atom (Lewis acidity) of DMAC by performing quantum chemical calculations using, for example, the density functional theory (DFT).

[0015] The DFT calculations can be carried out by using, for example, the following means and set conditions well-known in the art: · Calculation software Gaussian R 03 W (version 6.1) · Molecular modeling software (for calculating bond distances and structure description) GaussView 4.1 Function used in DFT calculations · Correlation exchange functional: B3LYP · Basis function: 6-31G (double-zeta basis) · Polarization basis function: d, p

[0016] Examples of nitrogen-containing organic compounds include saturated heterocyclic compounds such as pyrrolidine, piperidine, piperazine, morpholine, quinuclidine, 1,4-diazabicyclo[2.2.2.]octane, and unsaturated heterocyclic compounds such as pyrazole, imidazole, pyridine, pyridazine, pyrimidine, pyrazine, oxazole, thiazole, 4-dimethylaminopyridine, indole, quinoline, isoquinoline, purine, 1-methylimidazole, 1-ethylimidazole, 1-butylimidazole.

[0017] Particularly preferred nitrogen-containing organic compounds in the present invention are conjugated heterocyclic compounds containing at least one nitrogen atom and having a 5-membered ring and / or 6-membered ring skeleton. Particularly preferred conjugated heterocyclic compounds include, but are not limited to, pyridine, 2,6-dimethylpyridine, 2,4,6-trimethylpyridine, 2,6-diethylpyridine, 2,6-diisopropylpyridine, 2-methylpyridine, 4-methylpyridine, quinoline, isoquinoline, o-bipyridine, 1-methylimidazole, etc.

[0018] The complex formed from the dialkylaluminum halide and nitrogen-containing organic compound of the present invention is formed with 2 moles of dialkylaluminum halide per 1 mole of nitrogen-containing organic compound. For example, a complex formed from dimethylaluminum chloride and pyridine may have the following structure. [ka]

[0019] The method for forming the complex of the present invention is not particularly limited, but for example, it can be carried out by dissolving dialkylaluminum in an organic solvent and adding the nitrogen-containing organic compound of the present invention to the solution. The fraction containing the formed complex can be separated by precipitation as an unwanted fraction in the organic solvent and isolated. The nitrogen-containing organic compound may be added continuously or in batches, but it is preferably added dropwise in a continuous manner.

[0020] There are no particular restrictions on the type of organic solvent used, but for example, hydrocarbon solvents can be used. Preferably, the hydrocarbon solvent is hydrophobic and poorly reactive. Examples of such organic solvents include saturated hydrocarbon solvents with 4 to 18 carbon atoms and aromatic hydrocarbon solvents with 6 to 12 carbon atoms. For example, at least one selected from the group consisting of saturated hydrocarbon solvents and aromatic hydrocarbon solvents can be used.

[0021] Specific examples of saturated hydrocarbon solvents with 4 to 18 carbon atoms include n-butane, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, n-dodecane, n-tridecane, n-detradecane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclodecane, o-menthane, m-menthane, p-menthane, decahydronaphthalene, and paraffins. n H 2n+2 Isoparaffins C n H 2n+2 Examples include the following. n-dodecane is particularly preferred.

[0022] Specific examples of aromatic hydrocarbon solvents having 6 to 12 carbon atoms include benzene, toluene, xylene, and naphthalene. Aromatic hydrocarbons may be unsubstituted or may have substituents selected from the group consisting of alkyl groups having 1 to 8 carbon atoms, cycloalkyl groups having 3 to 8 carbon atoms, and alkylene groups having 2 to 8 carbon atoms. Examples of alkyl groups having 1 to 8 carbon atoms that are substituents on aromatic hydrocarbons include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, n-hexyl, isohexyl, neohexyl, tert-hexyl, n-heptyl, isoheptyl, neoheptyl, tert-heptyl, n-octyl, isooctyl, neooctyl, and tert-octyl groups. Examples of cycloalkyl groups having 3 to 8 carbon atoms that are substituents on aromatic hydrocarbons include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of alkylene groups having 2 to 8 carbon atoms that are substituents on aromatic hydrocarbons include ethylene, propylene, and butylene groups.

[0023] Specific examples of the above aromatic hydrocarbons include cumene, o-cumene, m-cumene, p-cumene, propylbenzene, n-butylbenzene, sec-butylbenzene, tert-butylbenzene, 1-phenylpentane, 1-phenylheptane, 1-phenyloctane, 1,2-diethylbenzene, 1,4-diethylbenzene, mesitylene, 1,3-di-tert-butylbenzene, 1,4-di-tert-butylbenzene, di-n-pentylbenzene, tri-tert-butylbenzene, cyclohexylbenzene, indan, and tetralin.

[0024] While the use of a solvent is not essential for the formation of the complex of the present invention, its use is preferable. When a solvent is used, the amount is not particularly limited, but for example, it can be in the range of 0.1 mol to 100 mol per 1 mol of dialkylaluminum chloride, and preferably in the range of 0.5 mol to 10 mol.

[0025] <Manufacturing of Trialkylaluminum> As stated at the beginning, the complex of the present invention enables the efficient production of trialkylaluminum, particularly trimethylaluminum (TMAL), more safely and efficiently than conventionally known methods. Trialkylaluminum is an important substance used as a polymerization co-catalyst and in the production of organic semiconductor materials. Trialkylaluminum includes, for example, trimethylaluminum, triethylaluminum, and triisobutylaluminum, with trimethylaluminum being particularly useful industrially.

[0026] Conventional methods for producing trialkylaluminum had problems that needed to be solved not only in terms of safety, but also in terms of cost and the number of steps involved. For example, in the production of trialkylaluminum, when DMAC is reduced using metallic sodium, the yield is approximately 85%. To improve this yield, there are examples of adding fluorides (NaF, KF, CaF2) (Japanese Patent Publication No. 4-273884), but in that case, waste disposal due to the use of fluorides and treatment of unreacted metallic sodium become problematic. Also, when reducing DMAC with magnesium powder, it is necessary to use powder with a maximum diameter of 75 μm or less, use a dedicated solid-state reactor, and react under high-temperature conditions such as a reaction temperature of 140-180°C for 3-6 hours or more (US Patent No. 5380898). Similarly, to reduce DMAC with Al-Mg alloy powder, even finer particles (average particle size D50 = 5-20 μm) are used, and a long reaction time of 24 hours or more at a reaction temperature of 130°C is required (Japanese Patent Publication No. 2018-135300).

[0027] Remarkably, using the complex of the present invention, the conversion of DMAC to TMAL can be efficiently achieved in a short time under relatively mild conditions, without the need for the pulverization of metal catalysts, waste disposal, or handling of hazardous materials as in the past, and without the use of special equipment. Specifically, for example, when a complex formed with pyridine and DMAC was used, a conversion rate of over 95% was achieved in a few hours at a temperature of about 130°C, as shown in the examples.

[0028] To produce trialkylaluminum from the complex of the present invention formed from a dialkylaluminum halide and a nitrogen-containing organic compound, for example, the complex of the present invention is dispersed in an organic solvent used or usable for complex formation as described above, a metal catalyst, such as an aluminum-magnesium alloy or magnesium powder, is added, and the mixture is heated and stirred to efficiently convert the dialkylaluminum halogen constituting the complex to trialkylaluminum.

[0029] While the use of a solvent is not essential in the production of trialkylaluminum, its use is preferable. When a solvent is used, the amount is not particularly limited, but it can be in the range of, for example, 0.1 mol to 100 mol per mol of complex, and preferably in the range of 0.5 mol to 10 mol.

[0030] The amount of metal catalyst added, such as an aluminum-magnesium alloy or magnesium powder, is not particularly limited, but can be in the range of 1.0 mol to 100 mol per mol of complex, and preferably in the range of 1.0 mol to 10 mol.

[0031] The reaction temperature can be any temperature at which the reaction proceeds. 20°C to 200°C is preferred, and 50°C to 170°C is more preferred. There are no particular restrictions on the reaction time, but 1 to 12 hours is preferred, and 3 to 8 hours is more preferred.

[0032] The reaction method can be batch, semi-batch, or continuous, and there are no particular restrictions on its implementation. A vertical or horizontal pressure-resistant reaction vessel can be used as the reaction apparatus. For example, a pressure-resistant autoclave with a stirrer can be used. Any commonly known type of impeller can be used, such as a propeller, turbine, paddle, inclined paddle, turbine blade, or large blade. Furthermore, a homogenizer can also be used.

[0033] The present invention further provides a preparation comprising a complex according to the present invention, namely a complex formed from a dialkylaluminum halide and a nitrogen-containing organic compound, wherein the bond distance between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of the dialkylaluminum halide located at the shortest distance to the nitrogen atom is less than 3.4 Å. Such a preparation is effective for producing, for example, trialkylaluminum. Such a composition may contain the complex dispersed in, for example, an organic solvent used or usable for complex formation as described above.

[0034] All references made herein are incorporated herein by reference in their entirety.

[0035] The embodiments of the present invention described below are for illustrative purposes only and do not limit the technical scope of the invention. The technical scope of the invention is limited solely by the claims. Modifications to the invention, such as additions, deletions, and substitutions of constituent elements of the invention, can be made without departing from the spirit of the invention. [Examples]

[0036] The present invention will be described in more detail below based on examples, but these examples are not intended to limit the present invention in any way.

[0037] <Example 1> DMAC-pyridine complex 68.2 g of n-dodecane was added to a 300 ml glass container purged with nitrogen, and then 22.0 g (0.24 mol) of dimethylaluminum chloride (DMAC) was added to prepare a mixed solution. The entire mixture was added to a 200 ml separatory funnel, and 2.0 g (0.025 mol) of pyridine (Py) was added dropwise. The mixture immediately separated into two layers, and only the lower layer was extracted. The yield was 7.3 g. Compositional analysis by 1H-NMR revealed a DMAC:Py ratio of 2:1, confirming the formation of a complex between DMAC and pyridine. 1H-NMR (500 MHz, THF-d8, 293K): 8.72(d, 2H), 8.14(t, 1H), 7.70(t, 2H), -0.76(s, 12H)

[0038] <Example 2> DMAC·2,6-dimethylpyridine complex The procedure was carried out in a manner almost identical to that of Example 1. 57.1 g of n-dodecane was added to a 300 ml glass container purged with nitrogen, and then 33.0 g (0.24 mol) of dimethylaluminum chloride (DMAC) was added to form a mixed solution. The entire volume of this mixture was added to a 200 ml separatory funnel, and 2.0 g (0.019 mol) of 2,6-dimethylpyridine (Lu) was added dropwise. The mixture immediately separated into two layers after the start of the dropwise addition, and only the lower layer component was extracted. The yield was 7.9 g. Compositional analysis by 1H-NMR revealed a composition of DMAC : Lu = 2:1, confirming the formation of a complex between DMAC and 2,6-dimethylpyridine. 1H-NMR (500 MHz, THF-d8, 293K): 7.43(t, 1H), 7.01(t, 2H), 2.45(s, 6H), -0.79(s, 12H)

[0039] <Example 3> Under substantially the same conditions as in Example 1, other nitrogen-containing organic compounds, specifically 2-methylpyridine, 4-methylpyridine, 2,4,6-trimethylpyridine, 2,6-diethylpyridine, 2,6-diisopropylpyridine, quinoline, isoquinoline, 1-methylimidazole, and 2,2-bipyridine, were also mixed with DMAC. Similarly, the mixture separated into two layers, confirming the formation of complexes with DMAC for each nitrogen-containing organic compound.

[0040] <Comparative Example 1> DMAC·2,6-di-tert-butylpyridine mixture The procedure was carried out in much the same manner as in Example 1. 57.1 g of n-dodecane was added to a 300 ml glass container that had been purged with nitrogen, and then 33.0 g, 0.2 mol of dimethylaluminum chloride (DMAC) was mixed to form a mixed solution. The entire volume of this mixture was added to a 200 ml separatory funnel, and 2.0 g, 0.010 mol of 2,6-di-tert-butylpyridine was added dropwise, but no layer separation was observed, and complex formation could not be confirmed.

[0041] <Regarding the conversion reaction from the complex to trimethylaluminum (TMAL)> <Example 4> Reaction of DMAC-pyridine composite with aluminum-magnesium alloys 15.7 g of n-dodecane and 3.59 g of aluminum-magnesium alloy (Al:Mg=42.5:57.5 (wt%)) were added to a 100 ml glass Schlenk tube purged with nitrogen to form a suspension. Then, 2.8 g of DMAC-pyridine complex was added dropwise, and the mixture was heated and stirred at 130°C for 5 hours. After lowering the reaction temperature to room temperature, 1H-NMR measurements were performed. The signal of the complex was consumed, and only the signal of TMAL was observed. The results are shown in Figure 1. The reaction yield of TMAL was 95%, achieving extremely high efficiency in conversion to TMAL compared to conventional methods.

[0042] <Example 5> Reaction of DMAC·2,6-dimethylpyridine with aluminum-magnesium alloys The DMAC·2,6-dimethylpyridine complex prepared in Example 2 was investigated for conversion to TMAL in the same manner as in Example 3. The reaction yield of TMAL was 96%, demonstrating extremely high efficiency in conversion to TMAL compared to conventional methods.

[0043] <Comparative Example 2> Reaction of DMAC·2,6-di-tert-butylpyridine mixture with aluminum-magnesium alloy 15.7 g of n-dodecane and 3.59 g of aluminum-magnesium alloy (Al:Mg=42.5:57.5 (wt%)) were added to a 100 ml glass Schlenk tube purged with nitrogen to form a suspension. Then, 6.2 g of DMAC·2,6-di-tert-butylpyridine mixture was added dropwise, and the mixture was heated and stirred at 130°C for 5 hours, but no conversion from DMAC to TMAL was observed. The results are shown in Figure 2.

[0044] The results from Examples 3-4 and Comparative Example 2 show that nitrogen-containing organic compounds capable of forming complexes with DMAC can be effectively utilized in the conversion from DMAC to TMAL.

[0045] <Consideration> As described above, nitrogen-containing organic compounds such as pyridine, 2,6-dimethylpyridine, 2-methylpyridine, 4-methylpyridine, 2,4,6-trimethylpyridine, 2,6-diethylpyridine, 2,6-diisopropylpyridine, quinoline, isoquinoline, 1-methylimidazole, and 2,2-bipyridine can form complexes when mixed with DMAC and can be effectively utilized for efficient conversion from DMAC to TMAL. In contrast, 2,6-di-tert-butylpyridine cannot form a complex with DMAC and cannot be effectively utilized for conversion from DMAC to TMAL. Therefore, we investigated the common physicochemical properties of nitrogen-containing organic compounds effective in the formation of the above complexes. Nitrogen-containing organic compounds such as pyridine formed complexes with DMAC, while 2,6-di-tert-butylpyridine, despite being a nitrogen-containing organic compound, did not form a complex. It is presumed that the coordination environment around the nitrogen atom is important for nitrogen-containing organic compounds to form complexes with DMAC. More specifically, it is presumed that whether or not complex formation is possible is determined by the bond distance between the N atom (Lewis basic) of the nitrogen-containing organic compound and the Al atom (Lewis acidic) of DMAC, which is theoretically assumed to occur when a complex is formed. Therefore, we performed quantum chemical calculations using the general-purpose density functional theory (DFT) and calculated the bond distance between the N atom (Lewis basic) and the Al atom (Lewis acidic) of DMAC for nitrogen-containing organic compounds that can form complexes.

[0046] The DFT calculation was performed using the following method. • Calculation software Gaussian R 03 W (version 6.1) • Molecular modeling software (for calculating bond distances and plotting structures) GaussView 4.1 Functions used in DFT calculations • Correlation-exchange functional: B3LYP • Basis set: 6-31G (double-zeta basis) • Polarization basis functions: d, p

[0047] Furthermore, in order to reduce the time required for DFT calculations (reduce the computational load), the bond distance was calculated assuming that the formed complex was a 1:1 complex of DMAC:nitrogen-containing organic compound. [ka]

[0048] The results are shown in Figure 3. The calculated N-Al bond distance for complexes formed with nitrogen-containing organic compounds capable of complex formation was in the range of 2.0 to 2.2 Å. On the other hand, for di-tert-butylpyridine, a nitrogen-containing organic compound that cannot form complexes, the DFT calculation did not converge, and the bond distance could not be determined. Therefore, based on the sum of the van der Waals radii of the N and Al atoms, it is estimated that if di-tert-butylpyridine and DMAC were to form a complex, the bond distance would be approximately 3.4 Å. Therefore, if the calculated N-Al bond distance in the complex formed by a nitrogen-containing organic compound capable of complex formation is less than 3.4 Å, complex formation is achieved, and as a result, it can be expected that it can be effectively utilized in the conversion from DMAC to TMAL.

Claims

1. A complex formed from dimethylaluminum chloride and a nitrogen-containing organic compound selected from the group consisting of pyridine and 2,6-dimethylpyridine, The molar ratio of dimethylaluminum chloride to the nitrogen-containing organic compound is 2:1, and The nitrogen-containing organic compound coordinates to the aluminum atom of dimethylaluminum chloride via its nitrogen atom. A complex in which the bond distance between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of dimethylaluminum chloride located at the shortest distance to the nitrogen atom is 2.0 or more and less than 3.4 Å.

2. The complex according to claim 1, characterized in that the bond distance between the nitrogen atom and the aluminum atom of the complex is in the range of 2.0 to 2.2 Å.

3. A complex is formed by mixing dimethylaluminum chloride and a nitrogen-containing organic compound selected from the group consisting of pyridine and 2,6-dimethylpyridine in an organic solvent, wherein the dimethylaluminum chloride and the nitrogen-containing organic compound are used to form the complex. The molar ratio of dimethylaluminum chloride to the nitrogen-containing organic compound is 2:1, and The nitrogen-containing organic compound coordinates to the aluminum atom of dimethylaluminum chloride via its nitrogen atom. A method for forming a complex in which the bond distance between the nitrogen atom of the nitrogen-containing organic compound and the aluminum atom of dimethylaluminum chloride located at the shortest distance to the nitrogen atom is 2.0 or more and less than 3.4 Å.

4. The method according to claim 3, wherein the complex is isolated as an insoluble fraction in the organic solvent.

5. The method according to claim 3 or 4, wherein the organic solvent is a hydrocarbon solvent.

6. The method according to any one of claims 3 to 5, wherein the hydrocarbon solvent is at least one selected from the group consisting of saturated hydrocarbon solvents having 4 to 18 carbon atoms and aromatic hydrocarbon solvents having 6 to 12 carbon atoms.

7. The method according to any one of claims 3 to 6, wherein the hydrocarbon solvent is n-dodecane.

8. A preparation for use in the production of trialkylaluminum, comprising the complex described in claim 1 or 2.

9. A method for producing trialkylaluminum using the complex described in claim 1 or 2.

Images