A method for preparing lanthanum complex

Abstract

The invention discloses a method for preparing a lanthanum complex, comprising the following steps: S1, mixing a tetrahydrofuran solution of an alkyl lithium and a lanthanum chloride bis (lithium chloride) complex under a protective atmosphere, reacting at -30°C to -10°C for 0.5-3h to obtain a reaction solution containing an alkyl lanthanum; S2, mixing a tetrahydrofuran solution of a ligand with an active hydrogen with the reaction solution, reacting at room temperature for 0.5-8h to obtain a lanthanum complex. The present invention produces an alkyl lanthanum by reacting an alkyl lithium with a lanthanum chloride bis (lithium chloride) complex, then directly adding a ligand with an active hydrogen, and the alkyl lanthanum and the ligand further react to obtain a lanthanum complex, and the one-pot method is adopted for preparation, and no intermediate product purification step is required, the process is simple, and the raw material cost is low, the conversion rate is high, and the product purity is high, thereby avoiding the problems of low product purity, low conversion rate or complex process of the traditional preparation method of the lanthanum complex.

Description

Technical Field

[0001] The invention relates to the technical field of lanthanum complexes, and in particular to a method for preparing a lanthanum complex. Background Art

[0002] The chemical formula of lanthanum oxide is La 2 O 3 , is a white solid powder with a high melting point (2315°C) and a high boiling point (4200°C). It is widely used in materials science, especially in advanced processes. The applications of lanthanum oxide in advanced processes include:

[0003] In the field of optical glass, lanthanum oxide is used to manufacture precision optical glass and optical fibers. These materials have important applications in fields such as cameras, microscope lenses and prisms of advanced optical instruments.

[0004] In the electronics industry, lanthanum oxide is used to make ceramic capacitors and piezoelectric ceramic dopants, which are critical to the performance of electronic devices.

[0005] In the field of catalysts, lanthanum oxide is used in the separation and refining process in the petroleum industry, and as a catalyst in certain chemical reactions, such as the oxidative coupling of methane to produce ethane and ethylene.

[0006] In the field of transparent ceramics, lanthanum oxide can be used to prepare transparent ceramics, which have potential applications in optical devices, wear-resistant materials and high-temperature resistant materials.

[0007] In the field of luminescent materials, lanthanum oxide is also used to prepare X-ray luminescent materials, which are used in medical imaging and security detection equipment.

[0008] Lanthanum oxide nanostructures have also been studied in the field of magnetic materials, where they may play a role in data storage and magnetic sensors.

[0009] In the field of nuclear radiation detection, certain forms of lanthanum oxide have also been studied for use in nuclear radiation detection.

[0010] In the field of high-temperature heating elements, the high-temperature stability of lanthanum oxide makes it suitable for the manufacture of high-temperature heating elements, which have important applications in the aviation, aerospace and power industries.

[0011] This shows the diversity and importance of lanthanum oxide in modern science and industry. With the development of materials science and nanotechnology, the potential application areas of lanthanum oxide are still expanding. Currently, the commonly used precursor source materials for depositing lanthanum oxide are lanthanum complexes such as tris(N,N'-diisopropylcarbamidyl)lanthanum(III) and tris(isopropylcyclopentadienyl)lanthanum(III).

[0012] However, there are two main methods for preparing lanthanum complexes: one is to use a lanthanum chloride tetrahydrofuran complex to react with a ligand-related potassium salt, etc., the product obtained by this method has low purity and low conversion rate, and will cause a large waste of the ligand potassium salt, etc.; the other is to use a lanthanum chloride tetrahydrofuran complex and bis(trimethylsilyl) potassium amide to react to prepare a tris[bis(trimethylsilyl)amino]lanthanum intermediate product, purify the intermediate product, and then react the intermediate product with the ligand to obtain the target product. The product prepared by this method has high purity, but the process is complicated.

[0013] Therefore, it is of great significance to develop a method for preparing lanthanum complexes with simple process, high conversion rate and high product purity. Summary of the invention

[0014] The technical problem to be solved by the present invention is to provide a method for preparing a lanthanum complex, wherein an alkyl lanthanum intermediate product is prepared by reacting a lanthanum chloride bis(lithium chloride) complex with an organic lithium reagent, and then a target product is prepared by reacting the alkyl lanthanum with a corresponding ligand. The raw materials are cheap and the conversion rate is high. The preparation method is a one-pot method, and no additional purification step is required for the intermediate product. The entire process is simple and easy to operate and is suitable for large-scale production.

[0015] In order to solve the above technical problems, the present invention provides a method for preparing a lanthanum complex, comprising the following steps:

[0016] S1. Under a protective atmosphere, alkyl lithium and lanthanum chloride bis(lithium chloride) complex LaCl 3 ·2LiCl solution is mixed and reacted at -30℃ ~ -10℃ to obtain a reaction solution containing alkyl lanthanum;

[0017] S2. Mixing a ligand solution having an active hydrogen with the reaction solution, and reacting them at room temperature to obtain a lanthanum complex.

[0018] The invention produces alkyl lanthanum by reacting alkyl lithium with lanthanum chloride bis(lithium chloride) complex, and then directly adds a ligand with an active hydrogen, and further reacts the alkyl lanthanum with the ligand to obtain a lanthanum complex. The one-pot preparation method is adopted, and no intermediate product purification step is required. The process is simple, and the raw material cost is low, the conversion rate is high, and the product purity is high, thereby avoiding the problems of low product purity, low conversion rate or complex process in the traditional preparation method of lanthanum complex.

[0019] Furthermore, the molar ratio of the lanthanum chloride bis(lithium chloride) complex, the alkyl lithium and the ligand is 1:(2.5-3.5):(2-4), and the preferred molar ratio is 1:3:3.

[0020] Furthermore, the alkyl lithium is one or more of methyl lithium, n-butyl lithium, tert-butyl lithium and sec-butyl lithium, preferably methyl lithium and / or n-butyl lithium. In this case, the reaction formula of step S1 is formula (1), and the reaction formula of step S2 is formula (2):

[0021] LaCl 3 2LiCl + LiMe + (nBu)Li → La(nBu) m (Me) 3-m Formula (1);

[0022] La(nBu) m (Me) 3-m + HR→LaR 3 Formula (2);

[0023] Wherein, m=0, 1, 2 or 3, Me is a methyl group, nBu is a n-butyl group, and HR is a ligand with an active hydrogen.

[0024] Furthermore, the ligand is a cyclopentadiene derivative or an amidine ligand, and the corresponding ligand is selected according to the product.

[0025] Further, the amidine ligand is selected from N,N'-diisopropylformamidine, N,N'-diisopropylacetamidine, N,N'-diethylformamidine, N,N'-diethylacetamidine, N,N'-ditert-butylformamidine or N,N'-ditert-butylacetamidine, including but not limited to these.

[0026] Further, the cyclopentadiene derivative is selected from cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, n-propylcyclopentadiene, isopropylcyclopentadiene, tert-butylcyclopentadiene, butylcyclopentadiene or sec-butylcyclopentadiene, including but not limited to these.

[0027] Furthermore, the reaction time of S1 is 0.5-3h, preferably 1h.

[0028] Furthermore, the reaction time of S2 is 0.5-8h, preferably 3h.

[0029] Furthermore, in S2, after the reaction is completed, filtering and sublimation steps are also included.

[0030] Furthermore, the protective atmosphere is one or more of nitrogen, argon and helium.

[0031] Furthermore, the solvents of the lanthanum chloride bis(lithium chloride) complex solution and the ligand solution are independently selected from one or more of tetrahydrofuran, diethyl ether and tert-methyl ether.

[0032] Beneficial effects of the present invention:

[0033] The invention produces alkyl lanthanum by reacting alkyl lithium with lanthanum chloride bis(lithium chloride) complex, and then directly adds a ligand with an active hydrogen, and the alkyl lanthanum and the ligand further react to obtain a lanthanum complex. The one-pot preparation method is adopted, and no intermediate product purification step is required, so the process is simple. Meanwhile, the method has the advantages of low raw material cost, high conversion rate and high product purity, and avoids the problems of low product purity, low conversion rate or complex process in the traditional preparation method of lanthanum complex. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the NMR spectrum of the product obtained in Example 1 of the present invention;

[0035] Figure 2 It is the NMR spectrum of the product obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0037] This embodiment provides a method for preparing a lanthanum complex, comprising the following steps:

[0038] S1. Under a protective atmosphere, alkyl lithium and lanthanum chloride bis(lithium chloride) complex solution are mixed and reacted at -30°C to -10°C to obtain a reaction solution containing alkyl lanthanum;

[0039] S2. Mixing a ligand solution having an active hydrogen with the reaction solution, and reacting them at room temperature to obtain a lanthanum complex.

[0040] Specifically, the molar ratio of the lanthanum chloride bis(lithium chloride) complex, the alkyl lithium and the ligand is 1:(2.5-3.5):(2-4), for example, 1:2.5:2.5, 1:3.5:3.5, 1:3:3, 1:3:4. Preferably, the molar ratio of the alkyl lithium, the lanthanum chloride bis(lithium chloride) complex and the ligand is 1:3:3.

[0041] Specifically, the alkyl lithium is one or more of methyl lithium, n-butyl lithium, tert-butyl lithium and sec-butyl lithium, preferably methyl lithium and / or n-butyl lithium. In this case, the reaction formula of step S1 is formula (1), and the reaction formula of step S2 is formula (2):

[0042] LaCl 3 2LiCl + LiMe + (nBu)Li → La(nBu) m (Me) 3-m Formula (1);

[0043] La(nBu) m(Me) 3-m + HR→LaR 3 Formula (2);

[0044] Wherein, m=0, 1, 2 or 3, Me is a methyl group, nBu is a n-butyl group, and HR is a ligand with an active hydrogen.

[0045] In the present invention, the intermediate lanthanum alkyl may be La(nBu)(Me) 2 、La(nBu) 2 (Me), La(nBu) 3 ,La(Me) 3 One or more of the .

[0046] More preferably, the alkyl lithium is methyl lithium and n-butyl lithium in a molar ratio of 1:2.

[0047] Specifically, the ligand is a cyclopentadiene derivative or an amidine ligand, and the corresponding ligand is selected according to the product; wherein the amidine ligand is selected from N,N'-diisopropylformamidine, N,N'-diisopropylacetamidine, N,N'-diethylformamidine, N,N'-diethylacetamidine, N,N'-di-tert-butylformamidine or N,N'-di-tert-butylacetamidine; the cyclopentadiene derivative is selected from cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, n-propylcyclopentadiene, isopropylcyclopentadiene, tert-butylcyclopentadiene, butylcyclopentadiene or sec-butylcyclopentadiene.

[0048] Specifically, the reaction time of S1 is 0.5-3h, for example: 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, preferably 1h; the reaction time of S2 is 0.5-8h, for example: 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, preferably 3h; in S2, after the reaction is completed, it also includes filtration and sublimation steps to extract the product.

[0049] Specifically, the protective atmosphere is one or more of nitrogen, argon and helium; the solvents of the lanthanum chloride bis(lithium chloride) complex solution and the ligand solution are independently selected from one or more of tetrahydrofuran, ether and tert-methyl ether.

[0050] In this embodiment, alkyl lanthanum is produced by reacting alkyl lithium with lanthanum chloride bis(lithium chloride) complex, and then a ligand with an active hydrogen is directly added. The alkyl lanthanum and the ligand further react to obtain a lanthanum complex. The one-pot preparation method is adopted, and no intermediate product purification step is required. The process is simple, and the raw material cost is low, the conversion rate is high, and the product purity is high. The problems of low product purity, low conversion rate or complex process in the traditional preparation method of lanthanum complex are avoided. Example 1

[0051] This embodiment relates to a method for preparing a lanthanum complex, specifically a method for preparing tris(N,N'-diisopropylcarbamidyl)lanthanum (III), comprising the following steps:

[0052] (1) Under nitrogen atmosphere, transfer LaCl into the reaction bottle. 3 ·Methyl lithium (0.2 mol, 1.6 mol / L) and n-butyl lithium (0.4 mol, 2.5 mol / L) were added to a tetrahydrofuran solution of 2LiCl (0.2 mol, 0.33 mol / L) at -30°C, and the reaction was continued at this temperature with stirring for 1 hour to obtain a reaction solution containing alkyl lanthanum.

[0053] (2) Add a tetrahydrofuran solution of N,N'-diisopropylformamidine (HFMD) (0.6 mol, 76.9 g) to the reaction solution of step (1), slowly raise the temperature to room temperature, reflux for 3 hours, filter after the reaction, dry the filtrate, and sublimate to obtain a white slightly yellowish solid tri(N,N'-diisopropylformamidine)lanthanum (III) (88.5 g, 0.17 mol), with a yield of 85% and an ICP purity of 5N. The product obtained in this example was subjected to H NMR spectrum detection, and the results are as follows: Figure 1 As shown, the product exists in the form of a dimer. Example 2

[0054] This embodiment relates to a method for preparing a lanthanum complex, specifically a method for preparing tri(isopropylcyclopentadienyl)lanthanum (III), comprising the following steps:

[0055] (1) Under nitrogen atmosphere, transfer LaCl into the reaction bottle. 3 ·Methyl lithium (0.2 mol, 1.6 mol / L) and n-butyl lithium (0.4 mol, 2.5 mol / L) were added to a tetrahydrofuran solution of 2LiCl (0.2 mol, 0.33 mol / L) at -30°C, and the reaction was continued at this temperature with stirring for 1 hour to obtain a reaction solution containing alkyl lanthanum.

[0056] (2) Add a tetrahydrofuran solution of isopropylcyclopentadiene (0.6 mol, 64.9 g) to the reaction solution of step (1), slowly raise the temperature to room temperature, reflux for 3 hours, filter after the reaction, dry the filtrate, and sublimate to obtain a light yellow liquid tri(isopropylcyclopentadienyl)lanthanum (III) (75.3, 0.168 mol), with a yield of 84% and an ICP purity of 5N. The product obtained in this example was subjected to H NMR spectrum detection, and the results are as follows: Figure 2 shown. Example 3

[0057] This embodiment relates to a method for preparing a lanthanum complex, specifically a method for preparing tris(N,N'-diisopropylcarbamidyl)lanthanum (III), comprising the following steps:

[0058] (1) Under nitrogen atmosphere, transfer LaCl into the reaction bottle. 3 ·Methyl lithium (0.4 mol, 1.6 mol / L) and n-butyl lithium (0.2 mol, 2.5 mol / L) were added to a tetrahydrofuran solution of 2LiCl (0.2 mol, 0.33 mol / L) at -30°C, and the reaction was continued at this temperature with stirring for 1 hour to obtain a reaction solution containing alkyl lanthanum.

[0059] (2) Add a tetrahydrofuran solution of N,N'-diisopropylformamidine (HFMD) (0.6 mol, 76.9 g) to the reaction solution of step (1), slowly heat the mixture back to room temperature, and reflux for 3 hours. After the reaction is completed, filter the mixture, dry the filtrate, and sublimate the mixture to obtain a white slightly yellowish solid tri(N,N'-diisopropylformamidine)lanthanum (III) (84.3 g, 0.162 mol). The yield is 81% and the purity according to ICP test is 5N. Comparative Example 1

[0060] This embodiment relates to a method for preparing a lanthanum complex, specifically a method for preparing tris(N,N'-diisopropylcarbamidyl)lanthanum (III), comprising the following steps:

[0061] (1) Under nitrogen atmosphere, transfer LaCl into the reaction bottle. 3 ·Methyl lithium (0.3 mol, 1.6 mol / L) was added to a tetrahydrofuran solution of 2LiCl (0.2 mol, 0.33 mol / L) at -30°C and the reaction was continued at this temperature with stirring for 1 hour to obtain a reaction solution containing alkyl lanthanum.

[0062] (2) Add a tetrahydrofuran solution of N,N'-diisopropylformamidine (HFMD) (0.6 mol, 76.9 g) to the reaction solution of step (1), slowly raise the temperature to room temperature, reflux for 3 hours, filter after the reaction is completed, dry the filtrate, and sublimate to obtain a white slightly yellowish solid tri(N,N'-diisopropylformamidine)lanthanum (III) (75.0 g, 0.144 mol), with a yield of 72% and an ICP test purity of 5N.

[0063] From the comparison between Example 1 and Comparative Example 1, it can be seen that when the molar ratio of lanthanum chloride bis(lithium chloride) complex and alkyl lithium exceeds the limited range of 1:(2.5-3.5) of the present invention, the yield decreases significantly. Among them, when the molar ratio of lanthanum chloride bis(lithium chloride) complex and alkyl lithium is 1:1.5, the yield is only 72%.

[0064] It can be seen from Examples 1-3 that the product obtained by the preparation method of the lanthanum complex of the present invention has high purity and high conversion rate. In particular, when the alkyl lithium is selected as methyl lithium and n-butyl lithium in a molar ratio of 1:2 in Examples 1 and 2, the conversion rate is as high as 85% and 84%. When the alkyl lithium is selected as methyl lithium and n-butyl lithium in a molar ratio of 2:1 in Example 3, the conversion rate is reduced to 81%, but still has a good conversion rate.

[0065] In summary, the preparation method of the lanthanum complex of the present invention prepares an alkyl lanthanum intermediate product by using a lanthanum chloride bis(lithium chloride) complex and an organic lithium reagent, wherein the organic lithium reagent is preferably methyl lithium and n-butyl lithium in a molar ratio of 1:2, and then the alkyl lanthanum intermediate product reacts with a corresponding ligand to prepare a target product, the raw materials are cheap, and the conversion rate is high, up to 85%; at the same time, the preparation method of the present invention is a one-pot method, and there is no need for an additional purification step for the intermediate product. The entire process is simple and easy to operate, and is suitable for large-scale production.

[0066] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for preparing a lanthanum complex, characterized in that: The steps include: S1. Under a protective atmosphere, mixing alkyl lithium with a lanthanum chloride bis(lithium chloride) complex solution, reacting at -30°C to -10°C to obtain a reaction solution containing alkyl lanthanum; S2, mixing a ligand solution with an active hydrogen with the reaction solution, reacting at room temperature to obtain a lanthanum complex; The ligand is a cyclopentadiene derivative, the cyclopentadiene derivative is selected from cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, n-propylcyclopentadiene, isopropylcyclopentadiene, tert-butylcyclopentadiene, n-butylcyclopentadiene or sec-butylcyclopentadiene; The alkyl lithium is one or both of methyl lithium and n-butyl lithium; The general reaction formula of step S1 is formula (1), and the general reaction formula of step S2 is formula (2): LaCl3·2LiCl + LiMe + (nBu)Li → La(nBu) m (Me) 3-m Formula (1); La(nBu) m (Me) 3-m + HR→LaR3 formula (2); Where m=0, 1, 2 or 3.

2. The method for preparing the lanthanum complex according to claim 1, characterized in that: The molar ratio of the lanthanum chloride bis(lithium chloride) complex, alkyl lithium and ligand is 1:(2.5-3.5):(2-4).

3. The method for preparing the lanthanum complex according to claim 1, characterized in that: The reaction time of S1 is 0.5-3h, and the reaction time of S2 is 0.5-8h.

4. The method for preparing the lanthanum complex according to claim 1, characterized in that: In S2, after the reaction is completed, filtering and sublimation steps are also included.

5. The method for preparing the lanthanum complex according to claim 1, characterized in that: The protective atmosphere is one or more of nitrogen, argon and helium.

6. The method for preparing the lanthanum complex according to claim 1, characterized in that: The solvents of the lanthanum chloride bis(lithium chloride) complex solution and the ligand solution are independently selected from one or more of tetrahydrofuran, ether and methyl tert-butyl ether.

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