Tri (dimethylamino) gallium and preparation method thereof

Abstract

The invention discloses tris (dimethylamino) gallium and a preparation method thereof, and the preparation method comprises the following steps: S1, dimethylamine and n-butyllithium are subjected to a reaction to generate lithium dimethylamino; s2, lithium dimethylamino reacts with gallium trichloride to generate a tri (dimethylamino) gallium crude product; and S3, carrying out reduced pressure distillation on the tri (dimethylamino) gallium crude product at 100-110 DEG C for 25-35 minutes, carrying out reduced pressure sublimation at 125-130 DEG C, and condensing to obtain the tri (dimethylamino) gallium product. According to the preparation method, the reaction time is short, the raw materials are easy to obtain, the reaction yield and the production efficiency are high, and the purified product can be obtained in one step through sublimation, so that the product with the purity of 6N is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of gallium compound preparation, and specifically relates to tri(dimethylamino)gallium and a preparation method thereof. Background Art

[0002] Gallium oxide (Ga2O3) is an insulator at room temperature, thermally stable, and semiconductor above 500°C. Gallium oxide thin films have important applications, including thin film gas sensor devices, nanoscale optoelectronic devices, and passivation layers for gallium arsenide (GaAs)-based microelectronic devices. Gallium oxide thin films can be grown by physical vapor deposition, chemical vapor deposition (CVD), and atomic layer deposition (ALD). The growth of ALD films is completely controlled by the surface and is performed by exposing the substrate surface to alternating pulses of precursors separated by inert gas pulses. Due to surface-controlled growth, ALD provides excellent thickness control and almost perfect conformal coverage of the substrate. For these reasons, atomic layer deposition has been identified as an important growth technology for microelectronics manufacturing. To maximize its effectiveness in atomic layer deposition growth, the precursor must remain thermally stable on the substrate surface at the film growth temperature, but must also react quickly and efficiently with the second reactant to provide the desired material.

[0003] In order to deposit high-quality Ga2O3 films, Ga precursor materials have been widely studied, among which hexa(dimethylamino)digallium, i.e., tri(trimethylamino) dimer, is widely used as a gallium precursor for ALD deposition of gallium oxide films.

[0004] Chinese patent CN202310083071 describes the synthesis of crude tris(dimethylamino)gallium dimer, tris(dimethylamino)indium dimer, and tris(dimethylamino)aluminum dimer and the purification by step cooling recrystallization method. However, the purification method of this method has many steps in actual operation, which is inconvenient to operate, and it is difficult for the product to reach the required high purity. This method has problems such as cumbersome operation, strict reaction conditions and process control, and great safety hazards. Specifically, (1) during the filtration operation, the by-product lithium chloride particles are fine and light in specific gravity, which easily clogs the filter, making the operation difficult; (2) during the gradient cooling recrystallization process, the mother liquor and the crystallized product separation process need to be isolated from the air, which is difficult to control in the outside world; (3) the solvent required for repeated dissolution of the crystallized product is large, and the use of these large amounts of solvents may cause harm to the human body and environmental pollution, bringing difficulties to subsequent processing.

[0005] Patent JP2002220213A describes a method for synthesizing tri(dimethylamino)gallium. This method has a long reaction time, low efficiency, and the obtained product is not pure enough.

[0006] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art. Summary of the invention

[0007] The object of the present invention is to provide tri(dimethylamino)gallium and a preparation method thereof. The preparation method has a short reaction time and can obtain a product with a purity of 6N.

[0008] In order to achieve the above object, a technical solution provided by a specific embodiment of the present invention is as follows:

[0009] A method for preparing tri(dimethylamino)gallium comprises the following steps:

[0010] S1, reacting dimethylamine and n-butyl lithium to generate dimethyl lithium amide;

[0011] S2, reacting lithium dimethylamide with gallium trichloride to generate a crude tri(dimethylamino)gallium product;

[0012] S3. Distill the crude tri(dimethylamino)gallium product under reduced pressure at 100-110° C. for 25-35 min, and then sublimate and condense under reduced pressure at 125-130° C. to obtain a tri(dimethylamino)gallium product.

[0013] In one or more embodiments of the present invention, the molar ratio of dimethylamine to n-butyl lithium is (3.6-4.5): (3.03-3.04).

[0014] In one or more embodiments of the present invention, the molar ratio of dimethylamine to gallium trichloride is (3.6-4.5):1.

[0015] In one or more embodiments of the present invention, in step S1, n-butyl lithium and an alkane solvent are first mixed, and then dimethylamine is added to react, and the molar ratio of n-butyl lithium to the alkane solvent is 1:(2-4).

[0016] In one or more embodiments of the present invention, in step S1, n-butyl lithium and an alkane solvent are first mixed, dimethylamine is added at a temperature of -10 to 0° C., and then the temperature is raised and stirred.

[0017] In one or more embodiments of the present invention, after adding dimethylamine, the temperature is raised to 20-25° C. and stirred for 2-4 hours.

[0018] In one or more embodiments of the present invention, in step S2, gallium trichloride and an alkane solvent are first mixed and then reacted with lithium dimethylamide, and the molar ratio of gallium trichloride to the alkane solvent is 1:(4-5).

[0019] In one or more embodiments of the present invention, in step S2, gallium trichloride and an alkane solvent are first mixed, and then mixed with lithium dimethylamide at a temperature of -10 to 0°C, and then heated and stirred.

[0020] In one or more embodiments of the present invention, after mixing, the temperature is raised to 50-55° C. and stirred for 4-6 hours.

[0021] Another specific embodiment of the present invention provides a technical solution as follows:

[0022] A tri(dimethylamino)gallium is prepared by the above-mentioned preparation method of tri(dimethylamino)gallium.

[0023] Compared with the prior art, the present invention has the advantages of short reaction time, easy availability of raw materials, high reaction yield and production efficiency, etc. The alkane used as the raw material is non-toxic and can be reused, which is not only suitable for laboratory synthesis, but also suitable for large-scale synthesis. The appropriate excess ratio of the raw material not only reduces the generation of by-products, but also completely consumes the raw material gallium trichloride, which is helpful for the final purification and separation. The setting of the reaction temperature, i.e., low temperature, can not only reduce the generation of by-products, but also help control the reaction rate and reduce the effect of reaction exotherm. In addition, the selection of a single solvent not only reduces the influence of impurities of excessive solvents, but the low boiling point of the solvent also helps to remove the solvent later. Finally, for the purification of the product, the purified product can be obtained in one step by sublimation, and a product with a purity of 6N can be obtained in the end. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0025] A specific embodiment of the present invention provides a method for preparing tri(dimethylamino)gallium, comprising steps 1-3.

[0026] Step 1, reacting dimethylamine and n-butyl lithium to generate dimethyl lithium amide.

[0027] Specifically, the reaction formula in step 1 is Me2NH+ n BuLi→LiNMe2+C4H 10, under an inert atmosphere such as nitrogen, n-butyl lithium and an alkane solvent are mixed in a molar ratio of 1: (2-4), the temperature is controlled at -10-0°C, and dimethylamine is added, the molar ratio of dimethylamine to n-butyl lithium is (3.6-4.5): (3.03-3.04), after the addition of dimethylamine, the temperature is raised to 20-25°C and the reaction is continued for 2-4 hours to obtain a dimethylamino lithium alkane suspension. The alkane solvent is n-hexane, cyclohexane, pentane or heptane.

[0028] Choosing alkanes as solvents has a low boiling point and will not coordinate with raw materials or products. It can be effectively removed later to ensure the purity of the product. Adding dimethylamine and n-butyl lithium in an excessive ratio can ensure that the reaction is fully carried out, improve the yield and purity of the finished product, and reduce the generation of by-products. In addition, the reaction of dimethylamine and n-butyl lithium is exothermic. Cooling down before adding dimethylamine can reduce the probability of generating by-products due to the violent reaction, and then heating up to continue the reaction to ensure that the raw materials react completely.

[0029] Step 2, reacting lithium dimethylamide with gallium trichloride to generate a crude tri(dimethylamino)gallium product.

[0030] Specifically, the reaction formula in step 2 is GaCl3+3LiNMe2→Ga(NMe2)3+3LiCl. In an inert atmosphere such as nitrogen, gallium trichloride and an alkane solvent are mixed at a molar ratio of 1:(4-5) to prepare a gallium trichloride alkane suspension. The temperature is controlled to be -10-0°C. The gallium trichloride alkane suspension is added dropwise to the dimethylamino lithium alkane suspension. After the addition is completed, the temperature is raised to 50-55°C for reaction for 4-6 hours until no obvious gas is discharged from the tail gas. The reaction solution is allowed to stand for 10-14 hours, and the upper clear liquid and the lower solid are separated. The lower solid is mainly potassium chloride. The upper clear liquid is distilled under reduced pressure at 55-65°C and 1kPa-10kPa to remove the alkane solvent and the excessive undischarged dimethylamine, and then washed with an alkane solvent to remove impurities soluble in the alkane solvent, and finally dried at 70-80°C to obtain a crude tri(dimethylamino)gallium product.

[0031] The reaction of lithium dimethylamide and gallium trichloride is exothermic. The temperature is first controlled to be -10 to 0°C, and then the gallium trichloride alkane suspension and the lithium dimethylamide alkane suspension are mixed. This can reduce the possibility of producing a large amount of by-products due to the rapid temperature increase of the reaction, and then the temperature is increased to ensure that the reaction proceeds fully.

[0032] Step 3, distilling the crude tri(dimethylamino)gallium product under reduced pressure at 100-110° C. for 25-35 min, and then subliming and condensing under reduced pressure at 125-130° C. to obtain the tri(dimethylamino)gallium product.

[0033] Specifically, under an inert atmosphere such as nitrogen, the crude tri(dimethylamino)gallium product is transferred to a sublimator, the vacuum degree is adjusted to 1 kPa-100 Pa, the temperature is raised to 100-110° C., and the product is decompressed and extracted for 25-35 minutes without cooling to remove low-boiling impurities. The product is then raised to 125-130° C., a cooling cycle is applied to perform decompressed sublimation, and the product is collected from the sublimator after the sublimation is completed to obtain a tri(dimethylamino)gallium product.

[0034] The present invention is further described in detail below in conjunction with specific embodiments.

[0035] The n-butyl lithium used in the examples and comparative examples of the present invention is a n-hexane solution of n-butyl lithium with a molar concentration of 2.5M.

[0036] Example 1

[0037] Under nitrogen atmosphere, n-butyllithium (2.5M, 1L, 2.5mol) and n-hexane (1L) were added to a 5L reaction bottle, stirring was started, the temperature of the reaction bottle was reduced to -10°C, dimethylamine (3.5mol, 157g) was introduced under stirring, and the passage took about 1.5 hours. After the introduction was completed, the temperature was slowly returned to room temperature, and the stirring reaction was continued for 2 hours to obtain a n-hexane suspension of lithium dimethylamide.

[0038] In a nitrogen atmosphere, gallium trichloride (145g, 0.82mol) was dispersed in a n-hexane (500ml) solution to prepare a gallium trichloride n-hexane suspension. The gallium trichloride n-hexane suspension was added to a reactor containing a dimethylamine lithium n-hexane suspension while stirring. The reaction temperature was controlled to -10°C. After the addition was completed, the temperature was slowly raised to 50°C and stirred for 4 hours until no obvious gas was discharged from the tail gas. The reaction solution was allowed to stand for 12 hours, and the upper clear liquid and the lower solid were separated. The lower solid was mainly lithium chloride. The upper clear liquid was decompressed at 60°C and 1kPa to remove all the n-hexane solvent and the excess undischarged dimethylamine, and then washed with a n-hexane solution to remove a part of the impurities soluble in n-hexane. After drying at 70°C, a crude tri(dimethylamino)gallium product was obtained.

[0039] Under nitrogen atmosphere, transfer the crude tri(dimethylamino)gallium to a sublimator, adjust the vacuum degree of the vacuum system to 100 kPa, raise the temperature to 100°C, and without cooling, decompress and extract for 30 minutes to remove low-boiling impurities. Then raise the temperature to 130°C, pass a cooling cycle to perform decompressed sublimation, collect the product from the sublimator after sublimation, and obtain tri(dimethylamino)gallium product. According to calculation, the yield of tri(dimethylamino)gallium product is 72% and the purity is 6N.

[0040] Example 2

[0041] Under nitrogen atmosphere, n-butyllithium (2.5M, 0.994L, 2.485mol) and n-hexane (1L) were added to a 5L reaction bottle, stirring was started, the temperature of the reaction bottle was reduced to -8°C, dimethylamine (3.2mol, 144.27g) was introduced under stirring, and the passage was completed in about 1.5h. After the introduction was completed, the temperature was slowly returned to room temperature, and the stirring reaction was continued for 2h to obtain a n-hexane suspension of lithium dimethylamide.

[0042] In a nitrogen atmosphere, gallium trichloride (145g, 0.82mol) was dispersed in a n-hexane (500ml) solution to prepare a gallium trichloride n-hexane suspension. The gallium trichloride n-hexane suspension was added to a reactor containing a dimethylamine lithium n-hexane suspension while stirring. The reaction temperature was controlled to -5°C. After the addition was completed, the temperature was slowly raised to 50°C and stirred for 4 hours until no obvious gas was discharged from the tail gas. The reaction solution was allowed to stand for 12 hours, and the upper clear liquid and the lower solid were separated. The lower solid was mainly lithium chloride. The upper clear liquid was decompressed at 60°C and 1kPa to remove all the n-hexane solvent and the excess undischarged dimethylamine, and then washed with a n-hexane solution to remove a part of the impurities soluble in n-hexane. After drying at 70°C, a crude tri(dimethylamino)gallium product was obtained.

[0043] Under nitrogen atmosphere, transfer the crude tri(dimethylamino)gallium to a sublimator, adjust the vacuum degree of the vacuum system to 100 kPa, raise the temperature to 105°C, and remove low-boiling impurities by decompression extraction for 30 minutes without cooling. Then raise the temperature to 126°C, pass a cooling cycle to perform decompression sublimation, collect the product from the sublimator after sublimation, and obtain tri(dimethylamino)gallium product. According to calculation, the yield of tri(dimethylamino)gallium product is 71.6%, and the purity is 6N.

[0044] Example 3

[0045] Under nitrogen atmosphere, n-butyllithium (2.5M, 0.996L, 2.49mol) and n-hexane (1L) were added to a 5L reaction bottle, stirring was started, the temperature of the reaction bottle was reduced to 0°C, dimethylamine (3.28mol, 147.87g) was introduced under stirring, and the passage was completed in about 1.5h. After the introduction was completed, the temperature was slowly returned to room temperature, and the stirring reaction was continued for 2h to obtain a n-hexane suspension of lithium dimethylamide.

[0046] In a nitrogen atmosphere, gallium trichloride (145g, 0.82mol) was dispersed in a n-hexane (500ml) solution to prepare a gallium trichloride n-hexane suspension. The gallium trichloride n-hexane suspension was added to a reactor containing a dimethylamine lithium n-hexane suspension while stirring. The reaction temperature was controlled to be 0°C. After the addition was completed, the temperature was slowly raised to 50°C and stirred for 4 hours until no obvious gas was discharged from the tail gas. The reaction solution was allowed to stand for 12 hours, and the upper clear liquid and the lower solid were separated. The lower solid was mainly lithium chloride. The upper clear liquid was decompressed at 60°C and 1kPa to remove all the n-hexane solvent and the excess undischarged dimethylamine, and then washed with a n-hexane solution to remove a part of the impurities soluble in n-hexane. After drying at 70°C, a crude tri(dimethylamino)gallium product was obtained.

[0047] Under nitrogen atmosphere, transfer the crude tri(dimethylamino)gallium to a sublimator, adjust the vacuum degree of the vacuum system to 100 kPa, raise the temperature to 100°C, and remove low-boiling impurities by decompression extraction for 30 minutes without cooling. Then raise the temperature to 125°C, pass a cooling cycle to perform decompression sublimation, collect the product from the sublimator after sublimation, and obtain tri(dimethylamino)gallium product. According to calculation, the yield of tri(dimethylamino)gallium product is 71.1%, and the purity is 6N.

[0048] Comparative Example 1

[0049] Under nitrogen atmosphere, n-butyllithium (2.5M, 1L, 2.5mol) and n-hexane (1L) were added to a 5L reaction bottle, and stirring was started. Dimethylamine (3.5mol, 157g) was introduced under stirring at room temperature for about 1.5h. After the introduction was completed, the reaction was continued with stirring for 2h to obtain a n-hexane suspension of lithium dimethylamide.

[0050] In a nitrogen atmosphere, gallium trichloride (145g, 0.82mol) was dispersed in a n-hexane (500ml) solution to prepare a gallium trichloride n-hexane suspension. At room temperature, the gallium trichloride n-hexane suspension was added to a reactor containing a dimethylamine lithium n-hexane suspension while stirring. After the addition was completed, the temperature was slowly raised to 50°C and stirred for 4 hours until no obvious gas was discharged from the tail gas. The reaction solution was allowed to stand for 12 hours, and the upper clear liquid and the lower solid were separated. The lower solid was mainly lithium chloride. The upper clear liquid was decompressed at 60°C and 1kPa to remove all the n-hexane solvent and the excess undischarged dimethylamine, and then washed with a n-hexane solution to remove a part of the impurities soluble in n-hexane. After drying at 70°C, a crude tri(dimethylamino)gallium product was obtained.

[0051] Under nitrogen atmosphere, the crude tri(dimethylamino)gallium product was transferred to a sublimator, the vacuum degree of the vacuum system was adjusted to 100 kPa, the temperature was raised to 100°C, and the product was decompressed and extracted for 30 minutes without cooling to remove low-boiling impurities, and then the temperature was raised to 130°C, and a cooling cycle was passed to perform decompressed sublimation. After the sublimation was completed, the product was collected from the sublimator to obtain the tri(dimethylamino)gallium product. According to calculation, the yield of the tri(dimethylamino)gallium product was 64%, and the purity did not reach 6N.

[0052] Comparative Example 2

[0053] Under nitrogen atmosphere, n-butyllithium (2.5M, 0.984L, 2.46mol) and n-hexane (1L) were added to a 5L reaction bottle, stirring was started, the temperature of the reaction bottle was reduced to -10°C, dimethylamine (2.46mol, 110.9g) was introduced under stirring, and the passage was completed in about 1.5h. After the introduction was completed, the temperature was slowly returned to room temperature, and the stirring reaction was continued for 2h to obtain a n-hexane suspension of lithium dimethylamide.

[0054] In a nitrogen atmosphere, gallium trichloride (145g, 0.82mol) was dispersed in a n-hexane (500ml) solution to prepare a gallium trichloride n-hexane suspension. The gallium trichloride n-hexane suspension was added to a reactor containing a dimethylamine lithium n-hexane suspension while stirring. The reaction temperature was controlled to -10°C. After the addition was completed, the temperature was slowly raised to 50°C and stirred for 4 hours until no obvious gas was discharged from the tail gas. The reaction solution was allowed to stand for 12 hours, and the upper clear liquid and the lower solid were separated. The lower solid was mainly lithium chloride. The upper clear liquid was decompressed at 60°C and 1kPa to remove all the n-hexane solvent and the excess undischarged dimethylamine, and then washed with a n-hexane solution to remove a part of the impurities soluble in n-hexane. After drying at 70°C, a crude tri(dimethylamino)gallium product was obtained.

[0055] Under nitrogen atmosphere, the crude tri(dimethylamino)gallium product was transferred to a sublimator, the vacuum degree of the vacuum system was adjusted to 100 kPa, the temperature was raised to 100°C, and the product was decompressed and extracted for 30 minutes without cooling to remove low-boiling impurities, and then the temperature was raised to 130°C, and a cooling cycle was passed to perform decompressed sublimation. After the sublimation was completed, the product was collected from the sublimator to obtain the tri(dimethylamino)gallium product. According to calculation, the yield of the tri(dimethylamino)gallium product was 66%, and the purity did not reach 6N.

[0056] In summary, the present invention selects excessive amounts of dimethylamine and n-butyl lithium to prepare tri(dimethylamino)gallium, which not only reduces the generation of by-products, but also completely consumes the raw material gallium trichloride, which is helpful for the final purification and separation. In addition, the lower reaction temperature setting reduces the effect of reaction exotherm, thereby reducing the generation of by-products and helping to control the reaction rate. For the purification of the crude product, the purified product can be obtained at one time by sublimation, and the purity of the obtained product reaches 6N.

[0057] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0058] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing tri(dimethylamino)gallium, characterized in that: The steps include: S1, reacting dimethylamine and n-butyl lithium to generate dimethyl lithium amide; S2, reacting lithium dimethylamide with gallium trichloride to generate a crude tri(dimethylamino)gallium product; S3. Distill the crude tri(dimethylamino)gallium product under reduced pressure at 100-110° C. for 25-35 min, and then sublimate and condense under reduced pressure at 125-130° C. to obtain a tri(dimethylamino)gallium product.

2. The method for preparing tri(dimethylamino)gallium according to claim 1, characterized in that: The molar ratio of the dimethylamine to n-butyl lithium is (3.6-4.5): (3.03-3.04).

3. The method for preparing tris(dimethylamino)gallium according to claim 1, characterized in that: The molar ratio of dimethylamine to gallium trichloride is (3.6-4.5):

1.

4. The method for preparing tris(dimethylamino)gallium according to claim 1, characterized in that: In step S1, n-butyl lithium and an alkane solvent are first mixed, and then dimethylamine is added to react, and the molar ratio of n-butyl lithium to the alkane solvent is 1:(2-4).

5. The method for preparing tri(dimethylamino)gallium according to claim 1, characterized in that: In step S1, n-butyl lithium and an alkane solvent are first mixed, dimethylamine is added at a temperature of -10 to 0°C, and then the temperature is raised and stirred.

6. The method for preparing tris(dimethylamino)gallium according to claim 5, characterized in that: After the addition of dimethylamine is complete, the temperature is raised to 20-25°C and stirred for 2-4 hours.

7. The method for preparing tris(dimethylamino)gallium according to claim 1, characterized in that: In step S2, gallium trichloride and an alkane solvent are first mixed, and then reacted with lithium dimethylamide, and the molar ratio of gallium trichloride to the alkane solvent is 1:(4-5).

8. The method for preparing tris(dimethylamino)gallium according to claim 1, characterized in that: In step S2, gallium trichloride and an alkane solvent are first mixed, and then mixed with lithium dimethylamide at a temperature of -10 to 0°C, and then heated and stirred.

9. The method for preparing tris(dimethylamino)gallium according to claim 8, characterized in that: After mixing, heat to 50-55°C and stir for 4-6 hours.

10. A tris(dimethylamino)gallium, characterized in that The tri(dimethylamino)gallium is prepared by the preparation method of any one of claims 1 to 9.