Organic detection method of metal organic compounds

Abstract

The application discloses an organic detection method of a metal organic compound, and comprises the following steps: dissolving a sample to be detected in a deuterated solvent to obtain a solution to be detected; gradually reducing the temperature of the solution to be detected from a starting temperature to a final temperature, collecting the sample to be detected at different temperatures 1 H-NMR spectrum; comparing H-NMR spectra at different temperatures 1 H-NMR spectrum, and if an impurity peak originally overlapping with a main peak appears, the sample to be detected contains the impurity. The application separates the nuclear magnetic resonance signal peaks overlapping at normal temperature by gradient reduction of the temperature, realizes qualitative and quantitative analysis of trace impurities, and solves the problem of insufficient detection sensitivity of trace impurities in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of organometallic compound detection technology, and specifically relates to an organic detection method for organometallic compounds. Background Technology

[0002] In high-precision fields such as semiconductors and catalysts, the purity of organometallic compounds, such as trimethylaluminum (TMA) and dimethylaluminum chloride, directly affects the performance and quality of the final product. For the analysis of organometallic compounds, nuclear magnetic resonance spectroscopy (NMR), especially proton NMR spectroscopy (1H NMR), is crucial. 1 ¹H-NMR is a key analytical method for identifying the structure of this type of compound and detecting trace impurities (such as residual solvents, hydrolysis products, homologues, etc.).

[0003] Currently, commonly used methods for detecting organometallic compounds involve routine procedures performed at room temperature (e.g., 25°C). 1 The typical procedure for H-NMR detection is as follows: the sample is dissolved in a deuterated solvent, and the spectrum is acquired at room temperature. The purity and structure of the sample are determined by analyzing information such as chemical shift and integral area. However, for organometallic compounds and their impurities with similar structures or complex chemical environments, their characteristic peaks often overlap significantly at room temperature, making it impossible for the above methods to accurately identify and quantify them. Summary of the Invention

[0004] The purpose of this invention is to provide an organic detection method for organometallic compounds, which separates overlapping nuclear magnetic resonance signal peaks at room temperature through gradient cooling, thereby achieving qualitative and quantitative analysis of trace impurities and solving the problem of insufficient sensitivity of existing technologies for the detection of trace impurities.

[0005] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0006] An organic detection method for organometallic compounds, the organic detection method comprising the following steps:

[0007] The sample to be tested is dissolved in a deuterated solvent to obtain the test solution;

[0008] The temperature of the solution to be tested was lowered from the initial temperature gradient to the final temperature, and samples were collected at different temperatures. 1 H-NMR spectrum;

[0009] Comparison at different temperatures 1 If an impurity peak that was originally superimposed on the main peak appears in the H-NMR spectrum, then the sample to be tested contains that impurity.

[0010] In one or more embodiments of the present invention, the starting temperature is 20°C to 30°C.

[0011] In one or more embodiments of the present invention, the final temperature is less than or equal to 0°C.

[0012] In one or more embodiments of the present invention, the final temperature is -100°C.

[0013] In one or more embodiments of the present invention, the final temperature is -50°C to -80°C.

[0014] In one or more embodiments of the present invention, the step size of the gradient cooling is 10°C to 30°C.

[0015] In one or more embodiments of the present invention, the equilibrium time for each temperature during the gradient cooling process is 5 min to 10 min.

[0016] In one or more embodiments of the present invention, the deuterated solvent is at least one selected from deuterated toluene, deuterated benzene, deuterated chloroform, deuterated dichloromethane, and deuterated tetrahydrofuran.

[0017] In one or more embodiments of the present invention, the sample to be tested is at least one of trimethylaluminum, dimethylaluminum chloride, and methylaluminum dichloride.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. Improved detection sensitivity and resolution: By lowering the test temperature, the principle of slower molecular thermal motion and increased chemical shift differences at low temperatures was utilized to successfully separate overlapping NMR signal peaks at room temperature. For example, the characteristic peak of TMA splits from a single peak at room temperature into a 1:2 characteristic double peak at low temperature, making qualitative and quantitative analysis of trace TMA possible.

[0020] 2. Deciphering Molecular Dynamic Structure and Conformation: For organometallic compounds with coordination equilibrium, gradient cooling can "capture" the dynamic equilibrium state at different temperatures, allowing observation of peak shapes and integral ratio changes. This provides a powerful tool for inferring the molecular form in solution, conformational changes, and possible isomers, far exceeding the limitations of existing technologies that can only provide static structural information.

[0021] 3. Optimize testing conditions and avoid interference: Through variable temperature experiments, the optimal testing temperature can be systematically screened. For example, during the gradient cooling process, it was found that the peak shape was optimal at -70℃, which can guide subsequent experiments to select a safer testing temperature, such as -60℃, thereby improving the accuracy and safety of the detection. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a conventional 1H NMR spectrum of trimethylaluminum, dimethylaluminum chloride, and methylaluminum dichloride in one embodiment of the present invention;

[0024] Figure 2 The data collected in Embodiment 1 of this invention 1 H-NMR spectrum;

[0025] Figure 3 The data collected in Embodiment 2 of this invention 1 H-NMR spectrum. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0027] For organometallic compounds trimethylaluminum (TMA) and dimethylaluminum chloride (DMAC), the reaction of trimethylaluminum ((CH3)3Al) with aluminum trichloride (AlCl3) can be progressively converted to dimethylaluminum chloride ((CH3)2AlCl). With increasing amounts of aluminum trichloride (AlCl3), methylaluminum dichloride (CH3AlCl2) can be further generated. According to publicly available information, this conversion process is a stepwise chlorination reaction, with each step involving the substitution of a methyl group by a chlorine atom. The specific reaction pathway is as follows:

[0028] Step 1: Trimethylaluminum + aluminum trichloride → dimethylaluminum chloride ((CH3)2AlCl).

[0029] In this step, trimethylaluminum acts as a Lewis base, forming an adduct with the Lewis acid aluminum trichloride: (CH3)3Al + AlCl3 → (CH3)3Al·AlCl3. Under appropriate conditions, this adduct can undergo methyl transfer to produce intermediates such as dimethylaluminum chloride and dimethylaluminum chloride, but the major product is dimethylaluminum chloride.

[0030] Step 2: Dimethylaluminum chloride + aluminum trichloride → methylaluminum dichloride (CH3AlCl2).

[0031] In this step, dimethylaluminum chloride further reacts with aluminum trichloride to continue chlorination: (CH3)2AlCl + AlCl3 → CH3AlCl2 + (CH3)AlCl2 (equilibrium mixture).

[0032] In fact, the system forms an equilibrium mixture of various organoaluminum chlorides, including (CH3)3Al, (CH3)2AlCl, CH3AlCl2, and AlCl3.

[0033] Trimethylaluminum ((CH3)3Al), dimethylaluminum chloride ((CH3)2AlCl), and methylaluminum dichloride (CH3AlCl2) show overlapping signals in conventional 1H NMR spectra (solvent: deuterated benzene). Figure 1 It is difficult to distinguish, for example, TMA has a single peak at room temperature, but when it coexists with a specific solvent or impurity, the single peak cannot provide enough information to distinguish the impurity, making it difficult to confirm the presence of trace TMA.

[0034] To address the aforementioned issues, this invention employs gradient cooling to alter the relaxation time and chemical shift of different molecules or different groups within the same molecule in a sample, thereby separating overlapping signal peaks at room temperature and achieving more accurate qualitative and quantitative analysis.

[0035] A specific embodiment of the present invention provides an organic detection method for organometallic compounds, which specifically includes the following steps:

[0036] Step 1: Prepare the solution to be tested.

[0037] Specifically, the sample to be tested is placed in an NMR sample tube, and then a deuterated solvent is added to dissolve the sample. The NMR sample tube is then capped, and the cap is sealed with AB glue. The deuterated solvent is at least one of deuterated toluene, deuterated benzene, deuterated chloroform, deuterated dichloromethane, and deuterated tetrahydrofuran. The deuterated solvent can be selected based on the solubility and stability of the sample. The deuterated solvent used must remain liquid at the final temperature and not react with the sample to ensure... 1 Accuracy of H-NMR spectrum acquisition.

[0038] Step 2: Cool the solution to be tested from the initial temperature gradient to the final temperature, and collect the temperature data of the sample at different temperatures. 1 H-NMR spectrum.

[0039] Specifically, the NMR sample tube containing the test solution is placed in the NMR spectrometer, and the temperature parameters of the NMR spectrometer are set: the initial temperature and the final temperature are set, and the step size of the gradient cooling is set (10℃~30℃), so that the sample temperature decreases step by step according to the set gradient. During the gradient cooling process, sufficient equilibration time (5min~10min) is ensured at each temperature point. After stabilization, the sample is collected. 1 H-NMR spectrum.

[0040] The initial temperature is 20℃~30℃, specifically 20℃, 25℃, 30℃, and the final temperature is set to be less than or equal to 0℃, such as 0℃~-100℃, -50℃~-80℃, -60℃~-70℃. The final temperature can be adjusted according to different analytes. The purpose is to determine a critical separation temperature at which the separation effect between the target impurity peak and the main peak is optimal.

[0041] Step 3, compare the results at different temperatures. 1 If an impurity peak that was originally superimposed on the main peak appears in the H-NMR spectrum, then the sample to be tested contains that impurity.

[0042] Specifically, first analyze the spectrum: compare the spectra at different temperatures and observe the changes in the peak shape, chemical shift, and integral area of ​​the characteristic peaks; then determine the impurities: if at a certain low temperature, the impurity peak that originally overlapped with the main peak at room temperature is separated and forms an independent, integrable peak, then it is determined that the sample contains the impurity.

[0043] The present invention will be further described in detail below with reference to specific embodiments.

[0044] Example 1

[0045] The organic detection method for organometallic compounds in this embodiment is as follows:

[0046] Prepare a 16.4g mixture of trimethylaluminum and dimethylaluminum chloride, comprising 7.2087g of trimethylaluminum and 9.2504g of dimethylaluminum chloride, with a molar ratio of 1:1.

[0047] Take 50 μL of a mixture of trimethylaluminum and dimethylaluminum chloride and place it in an NMR sample tube. Then add 300 μL of deuterated toluene. Cap the NMR sample tube and seal the cap with AB glue.

[0048] The NMR sample tube was placed in the NMR spectrometer, with an initial temperature of 25℃ and a final temperature of -80℃. Gradual cooling was used, and samples were collected at different temperature points. 1 H-NMR spectrum.

[0049] like Figure 2As shown, data collected at temperature points of 25℃, -20℃, -50℃, -70℃, and -80℃... 1 In the H-NMR spectrum, at room temperature (25℃), the characteristic peaks of TMA and DMAC overlap and are difficult to distinguish. When the temperature drops to -20℃, the overlapping peaks begin to broaden and exhibit a "bulge". When the temperature drops to -50℃, the overlapping peaks separate into four peaks, two of which have relatively large peak widths. When the temperature drops to -70℃ and -80℃, the overlapping peaks completely separate into four completely separate peaks.

[0050] This embodiment successfully separated overlapping NMR signal peaks at room temperature and detected trimethylaluminum in dimethylaluminum chloride by lowering the test temperature to the range of -50°C to -80°C, utilizing the principle that molecular thermal motion slows down and chemical shift differences increase at low temperatures. Since the NMR equipment requires a long cooling time, -70°C was considered the optimal temperature.

[0051] Example 2

[0052] The organic detection method for organometallic compounds in this embodiment is as follows:

[0053] Prepare the following samples: 10 g of trimethylaluminum solution; 16.4 g of a mixture of trimethylaluminum and dimethylaluminum chloride (including 7.2087 g of trimethylaluminum and 9.2504 g of dimethylaluminum chloride, with a molar ratio of 1:1); 10 g of dimethylaluminum chloride solution; and 10.2710 g of a mixture of dimethylaluminum chloride and methylaluminum dichloride (including 4.6252 g of dimethylaluminum chloride and 5.6458 g of methylaluminum dichloride, with a molar ratio of 1:1). Take 50 μL each of the trimethylaluminum solution, the mixture of trimethylaluminum and dimethylaluminum chloride, the dimethylaluminum chloride solution, and the mixture of dimethylaluminum chloride and methylaluminum dichloride, and place them separately into four NMR sample tubes. Then add 300 μL of deuterated toluene. Cap the NMR sample tubes and seal the NMR caps with AB glue.

[0054] The NMR sample tube was placed in the NMR spectrometer, with an initial temperature of 25℃ and a final temperature of -80℃. Gradient cooling was used, and data was collected at -70℃. 1 H-NMR spectrum.

[0055] like Figure 3 As shown, trimethylaluminum eluted at 0.05 ppm and -0.48 ppm, with a ratio consistent with 1:2, which is consistent with its dimer characteristics. Dimethylaluminum chloride eluted at 0.20 ppm and -0.27 ppm, and the proportion of these peaks varied with temperature, indicating that the dimer of dimethylaluminum chloride exists in dynamic equilibrium at this temperature. Analysis suggests that this may be due to the dynamic equilibrium of the coordinating bridging bonds between Cl and CH3. Methylaluminum chloride eluted at -0.35 ppm and -0.43 ppm.

[0056] The detection limit for trimethylaluminum in dimethylaluminum chloride was calculated as follows: Detection limit = (3 * C concentration) / (S / N), i.e. (3 * 72.087 / (72.087 + 92.5036)) / (25491 * 3) * 1000000, and the final detection limit was 17.18 ppm (ug / g).

[0057] In summary, this invention utilizes gradient cooling to separate overlapping NMR signal peaks at room temperature by taking advantage of the principle that molecular thermal motion slows down and chemical shift differences increase at low temperatures. This allows for the acquisition of the main peak and impurity peaks, thereby accurately determining the presence of impurities corresponding to the impurity peaks and exhibiting excellent detection sensitivity.

[0058] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from the spirit or essential characteristics of this disclosure. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this disclosure.

[0059] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for the organic detection of organometallic compounds, characterized in that, The organic detection method includes the following steps: The sample to be tested is dissolved in a deuterated solvent to obtain the test solution; The temperature of the solution to be tested is decreased from the initial temperature to the final temperature by gradient, and the sample to be tested at different temperatures is collected 1 H-NMR spectrum; Comparison at different temperatures 1 If an impurity peak that was originally superimposed on the main peak appears in the H-NMR spectrum, then the sample to be tested contains that impurity.

2. The organic detection method for organometallic compounds according to claim 1, characterized in that, The initial temperature is 20℃~30℃.

3. The organic detection method for organometallic compounds according to claim 1, characterized in that, The final temperature is less than or equal to 0°C.

4. The organic detection method for organometallic compounds according to claim 3, characterized in that, The final temperature is -100℃.

5. The method for organic detection of organometallic compounds according to claim 3, characterized in that, The final temperature is -50℃ to -80℃.

6. The method for organic detection of organometallic compounds according to claim 1, characterized in that, The gradient cooling step size is 10℃~30℃.

7. The method for organic detection of organometallic compounds according to claim 1, characterized in that, During the gradient cooling process, the equilibrium time for each temperature is 5 to 10 minutes.

8. The method for organic detection of organometallic compounds according to claim 1, characterized in that, The deuterated solvent is at least one of deuterated toluene, deuterated benzene, deuterated chloroform, deuterated dichloromethane, and deuterated tetrahydrofuran.

9. The method for organic detection of organometallic compounds according to claim 1, characterized in that, The sample to be tested is at least one of trimethylaluminum, dimethylaluminum chloride, and methylaluminum dichloride.

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