A method for determining the purity of tetrakis(triphenylphosphine) complex

Abstract

The present invention discloses a method for determining the purity of a tetrakis(triphenylphosphine) complex. The method comprises deeply oxidizing the tetrakis(triphenylphosphine) complex with hydrogen peroxide, and then quantitatively determining the contents of triphenylphosphine and impurity chloride ions therein, thereby determining the chemical purity of the tetrakis(triphenylphosphine) complex. The method decomposes and analyzes multiple components in the system through an oxidative derivatization method, avoiding interference from other coordination compounds, and can effectively analyze the purity of the tetrakis(triphenylphosphine) complex.

Description

Technical Field

[0001] The invention belongs to the field of chemical industry, and particularly relates to a method for determining the purity of a tetrakis(triphenylphosphine) complex. Background Art

[0002] Tetrakis(triphenylphosphine) complexes ([(C6H5)3P]4X) are complexes centered on a metal atom and with four triphenylphosphines as ligands, such as tetrakis(triphenylphosphine)nickel, tetrakis(triphenylphosphine)palladium, and tetrakis(triphenylphosphine)platinum. They are commonly used as ligands for complex catalysts and are used in carbonyl synthesis reactions, as intermediates for phosphorus-containing Wittig reagents, as reducing agents, as flame retardants for ABS graft copolymers, as catalysts for olefin carbonylation, and as crosslinkers for epoxy resins. They have been widely used in the field of catalysis.

[0003] The synthesis of tetrakis(triphenylphosphine) complexes often involves reacting a metal chloride and triphenylphosphine in a solvent with a reducing agent. For example, patent CN 112159435A discloses a solvent-catalyst system using tetrahydrofuran as the solvent and zinc powder as the reducing agent. Nickel chloride hexahydrate and triphenylphosphine are reacted in the absence of oxygen, followed by filtration to produce brownish-yellow crystals of tetrakis(triphenylphosphine)nickel. Patent CN 114230486A discloses the synthesis of tetrakis(triphenylphosphine)nickel using DMF as the solvent and zinc powder as the reducing agent. However, the catalyst synthesized in the patent is directly used in the catalytic reaction, and the purity of the product is not measured. Li Junyang et al. reported a method for synthesizing tetrakis(triphenylphosphine)nickel using a mixed solvent of toluene and DMF, zinc powder as the reducing agent, and anhydrous nickel chloride and triphenylphosphine. Patent CN 114933612A discloses a method for synthesizing tetrakis(triphenylphosphine)palladium using palladium chloride and triphenylphosphine as raw materials and formic acid as the reducing agent in an ether solvent. The most commonly used method for synthesizing tetrakis(triphenylphosphine)palladium is to mix palladium chloride and triphenylphosphine and then add hydrazine hydrate as a reducing agent. Patent CN103833794 A discloses a method for synthesizing tetrakis(triphenylphosphine)platinum, which uses a platinum precursor and triphenylphosphine in a thionyl chloride solvent with hydrazine hydrate as a reducing agent.

[0004] These tetrakis(triphenylphosphine) complexes are highly susceptible to oxidation, making them difficult to analyze qualitatively and quantitatively using conventional methods such as infrared and LC. Currently, elemental analysis and ion titration are the primary methods for quantifying tetrakis(triphenylphosphine) complexes. However, the synthesis of these coordination compounds often produces complex products with alternate valence states. For example, in the synthesis of tetrakis(triphenylphosphine)nickel, reported products include bis(triphenylphosphine)nickel dichloride, tris(triphenylphosphine)nickel, and tris(triphenylphosphine)nickel chloride. Tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)platinum primarily contain bis(triphenylphosphine)palladium dichloride and bis(triphenylphosphine)platinum dichloride. This suggests that the synthesis of these products involves numerous components, which undoubtedly interferes with their qualitative and quantitative analysis. Furthermore, the differences in the C, H, and O content of different coordination products are minimal, making it difficult to determine their purity and composition based on elemental content. Partial oxidation during sample preparation prior to analysis may occur, particularly for readily oxidizable compounds, leading to deviations from the true results.

[0005] Derivatization is a common means in the analysis and detection process, such as after adopting methanol esterification derivatization for long-chain fatty acids, gas chromatography detection is adopted. Triphenylphosphine is also a kind of easily oxidized material, and there are also literature reports that adopt oxidation derivatization to detect after being more stable triphenylphosphine oxide, patent CN 117092226A discloses a detection method of triphenylphosphine in a tirofiban sample, which adopts hydrogen peroxide as a diluent to dilute the sample and then carry out high performance liquid chromatography detection. Patent CN103913521A discloses a method using triphenylphosphine as a derivatization reagent to detect hydrogen peroxide, and the triphenylphosphine oxide produced by quantitative oxidation measures hydrogen peroxide content. It can be seen from this that adopting oxidation derivatization to detect triphenylphosphine oxide is a more feasible solution. However, for four (triphenylphosphine) complexes, the method for quantitatively detecting its content by derivatization has not yet been reported.

[0006] Tetrakis (triphenylphosphine) complexes are usually used as catalysts, and key component therein is mainly the zero-valent metal of tetracoordination. For catalytic reaction, if the content of key component can not be accurately quantified, reaction may have a greater impact, reduce the repeatability of reaction process. Especially for tetrakis (triphenylphosphine) nickel, system is more complicated, has increased the possibility of side reaction, therefore it is necessary to detect its effective content, and it is necessary to analyze its possible impurity by certain method, thus judge the reliability of batch catalyst. In addition, to detect its actual content, each composition therein must be detected, it is impossible to solve the problem by single derivatization method, it is necessary to combine sufficient qualitative and quantitative by multiple methods, further increase its difficulty. Therefore, it is necessary to develop its detection method. Summary of the Invention

[0007] The present invention aims to provide a method for measuring the purity of tetrakis(triphenylphosphine) complex. The method is carried out by fully oxidizing the product system of the tetrakis(triphenylphosphine) complex and performing quantitative analysis to solve the difficulty caused by quantitative analysis due to the easily oxidizable characteristic of the tetrakis(triphenylphosphine) complex. After oxidation, suitable quantitative analysis methods can be used to detect the ion content and the total content of Ph3P groups in the system, and then the purity of the tetrakis(triphenylphosphine) complex can be calculated.

[0008] To achieve the above object, the present invention adopts the following technical solutions:

[0009] A method for determining the purity of a tetrakis(triphenylphosphine) complex, wherein the tetrakis(triphenylphosphine) complex has the structural formula [(C6H5)3P]4X, wherein X is a metal atom with a valence of zero. Specifically, the tetrakis(triphenylphosphine) complex is tetrakis(triphenylphosphine)nickel, tetrakis(triphenylphosphine)palladium, or tetrakis(triphenylphosphine)platinum.

[0010] The impurity components that still exist in tetrakis(triphenylphosphine)nickel after filtration and washing during the synthesis process include tris(triphenylphosphine)nickel, tris(triphenylphosphine)nickel chloride, and tris(triphenylphosphine)zinc chloride; the impurity components that still exist in tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)platinum after filtration and washing during the synthesis process include bis(triphenylphosphine)palladium chloride and bis(triphenylphosphine)platinum chloride, respectively.

[0011] The purity determination method is to deeply oxidize the tetrakis(triphenylphosphine) complex with hydrogen peroxide, and then quantitatively determine the contents of triphenylphosphine and impurity chloride ions therein, thereby determining the chemical purity of the tetrakis(triphenylphosphine) complex. The method specifically comprises the following steps:

[0012] 1) Determination of triphenylphosphine content

[0013] The tetrakis(triphenylphosphine) complex to be tested is dissolved in an organic solvent, and then a 30 wt.% hydrogen peroxide solution is added to the resulting solution to completely oxidize the sample to form a mixed solution of triphenylphosphine oxide and a metal oxide; after filtering the metal oxide in the mixed solution, the content of triphenylphosphine oxide in the diluted reaction solution is measured by liquid chromatography, and the content of triphenylphosphine is converted to obtain the content of triphenylphosphine;

[0014] 2) Determination of chloride ion impurity content

[0015] In an oxygen-free environment, a 30 wt.% hydrogen peroxide solution was added to the dried tetrakis(triphenylphosphine) complex to be tested, and the mixture was subjected to ultrasonication for 5 minutes. The solids were then removed by filtration. The filtrate was diluted with ultrapure water and filtered through a 0.22 μm organic filter to obtain a pretreatment solution. The chloride ion content in the pretreatment solution was then determined by ion chromatography.

[0016] 3) Determination of metal ion content

[0017] When the tetrakis(triphenylphosphine) complex to be measured is tetrakis(triphenylphosphine)nickel, the tetrakis(triphenylphosphine) complex to be measured needs to be digested, and the metal ion content in the digestion solution is measured by ICP-OES;

[0018] 4) Calculate the purity of the tetrakis(triphenylphosphine) complex based on the obtained substance content

[0019] For tetrakis(triphenylphosphine)nickel, the content of all Ph3P groups in the system was determined by high performance liquid chromatography. C p ； Considering that the sources of Cl in the system are mainly ZnCl2 and [(C6H5)3P]3NiCl (according to the research of Franz Ölscher et al., [(C6H5)3P]2NiCl2 will react with the product, so this component does not need to be considered), the Cl consumed by zinc chloride can be calculated. - content C Zn -Cl , and the rest are [(C6H5)3P]3Ni + Consumed Cl - content C[Ph 3 P] 3 Ni-Cl , based on which the nickel content corresponding to [(C6H5)3P]3NiCl is calculated C[Ph 3 P] 3 Ni Considering that the sources of Ph3P groups and Ni in the system are mainly [(C6H5)3P]3NiCl, [(C6H5)3P]3Ni and the product [(C6H5)3P]4Ni, that is,

[0020] ;

[0021] The molar ratio of nickel to triphenylphosphine (Ni:Ph3P) contributed by [(C6H5)3P]3Ni and the product [(C6H5)3P]4Ni in the system is thus obtained. Based on the molar ratio, the contents of [(C6H5)3P]3Ni and the product [(C6H5)3P]4Ni in the system are obtained, and the purity of [(C6H5)3P]4Ni is further obtained.

[0022] For tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)platinum, the components in the system are relatively simple, the generated hydrazine hydrochloride is removed, and the non-zero-valent triphenylphosphine ligands are only bis(triphenylphosphine)palladium dichloride and bis(triphenylphosphine)platinum dichloride, respectively. Therefore, the bis(triphenylphosphine)palladium dichloride or bis(triphenylphosphine)platinum dichloride can be subtracted from the measured triphenylphosphine content to obtain the tetrakis(triphenylphosphine)palladium and tetrakis(triphenylphosphine)platinum content, and then obtain its purity.

[0023] Furthermore, the amount of the organic solvent in step 1) is calculated as 7 mL per 0.1 g of tetrakis(triphenylphosphine) complex; the organic solvent includes any one of tetrahydrofuran, acetonitrile, ethanol, and methanol.

[0024] Furthermore, the volume ratio of the organic solvent and the hydrogen peroxide solution used in step 1) is 7:3.

[0025] Furthermore, the oxygen content of the oxygen-free environment in step 2) is lower than 10 ppm.

[0026] Furthermore, the amount of the hydrogen peroxide solution in step 2) is calculated based on 5 mL per 0.1 g of the tetrakis(triphenylphosphine) complex.

[0027] Furthermore, the dilution multiple in step 2) is 10 to 30 times.

[0028] The remarkable effects of the present invention are:

[0029] In view of the fact that tetrakis(triphenylphosphine) complexes are easily oxidized and difficult to analyze, the present invention provides an oxidative derivatization method. This method decomposes the organic matter, chloride ions, and metal ions in the complex and then measures their contents to determine the purity of the tetrakis(triphenylphosphine) complex. The main technical advantages of the present invention are:

[0030] (1) The present invention performs pretreatment in an oxygen-free environment, thereby avoiding the influence of the external atmosphere on the test results.

[0031] (2) The present invention uses excess hydrogen peroxide to oxidize the sample to ensure that the triphenylphosphine group is deeply oxidized and completely converted into triphenylphosphine oxide, thereby avoiding the influence of partial oxidation on the quantitative analysis of triphenylphosphine.

[0032] (3) The present invention fully analyzes chloride ions and cations, thus avoiding interference caused by different cations during the titration process.

[0033] (4) The present invention analyzes multiple components in the system, avoids interference from other coordination compounds, and can effectively analyze the purity of the tetrakis(triphenylphosphine) complex. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1is the reaction formula for converting triphenylphosphine into triphenylphosphine oxide in the present invention.

[0035] Figure 2 This is the standard working curve of triphenylphosphine drawn in Example 1.

[0036] Figure 3 This is the standard working curve of chloride ion drawn in Example 1. DETAILED DESCRIPTION

[0037] In order to make the contents of the present invention easier to understand, the technical solutions of the present invention are further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0038] The triphenylphosphine, hydrogen peroxide, tetrahydrofuran and titration indicator used in the examples were purchased, and ultrapure water was prepared using an ultrapure water machine.

[0039] The tetrakis(triphenylphosphine)nickel tested was prepared according to the method described in patent CN 112159435A, and tetrakis(triphenylphosphine)platinum was synthesized according to the literature (Zhang Xiongbo et al., "A New Synthesis Method for Tetrakis(triphenylphosphine)palladium"). All impurities were tested and their structures confirmed.

[0040] Example 1: Analysis of the content of tetrakis(triphenylphosphine)nickel:

[0041] 1. Determination of triphenylphosphine content in samples:

[0042] (1) Preparation of standard curve: Weigh 0.06 g, 0.08 g, 0.10 g, 0.12 g, and 0.14 g of triphenylphosphine standard sample, dissolve and dilute them in 7 ml of tetrahydrofuran, then add 3 ml of 30 wt.% hydrogen peroxide solution, shake well, and react for 5 min. Then, perform liquid chromatography quantitative detection on the standard solution. The liquid chromatography analysis conditions are as follows: eluent is 80% methanol-water solution, flow rate is 1 mL / min, chromatographic column: C18 reverse phase column, column temperature is 30 ℃, injection volume is 10 μL, and ultraviolet detector is used with a wavelength of 254 nm. Retention time is used for qualitative analysis and peak area is used for quantitative analysis. The standard working curve is drawn with the calculated triphenylphosphine oxide concentration as the horizontal axis and the detected peak area as the vertical axis.

[0043] (2) Repeatability and recovery determination: Weigh 0.1123 g of triphenylphosphine standard sample, add 7 mL of tetrahydrofuran and 3 ml of 30 wt.% hydrogen peroxide solution to prepare a standard solution, and repeat the injection 6 times using a liquid chromatograph. The relative standard deviation (RSD) is 0.53%. The above-prepared standard solution is added to the blank solution, and the recovery test is carried out. The recovery rate is 98%. Weigh 0.1012 g of triphenylphosphine oxide, add 7 mL of tetrahydrofuran and 3 ml of 30 wt.% hydrogen peroxide solution to prepare a triphenylphosphine oxide standard solution. The sample is tested using a liquid chromatograph. The sample recovery rate is 98.7%, indicating that the triphenylphosphine solution undergoes a quantitative oxidation reaction with hydrogen peroxide and is completely converted into triphenylphosphine oxide.

[0044] (3) Sample determination: In a glove box (oxygen content: 0.35 ppm), accurately weigh 0.1023 g of tetrakis(triphenylphosphine)nickel sample using a 12 ml analytical balance into a sealed 12 ml centrifuge tube. Then, add 7 ml of tetrahydrofuran to the centrifuge tube, followed by 3 ml of a 30 wt.% hydrogen peroxide solution. After reacting for 5 min, filter the reaction solution using a disposable filter to remove nickel oxide. Take 2 ml of the filtrate for liquid chromatography. The triphenylphosphine content was calculated based on the standard curve to be 92.871%.

[0045] 2. Determination of chloride ion content in samples:

[0046] (1) Standard curve preparation: Dilute the 1000 mg / L chloride ion standard stock solution with ultrapure water to different concentrations (0, 10, 20, 50, and 100 μg / L), and then perform chromatographic quantitative detection of the standard solution using ion chromatography. The ion chromatography analysis conditions are as follows: eluent: 3 mmol / L potassium hydroxide, flow rate: 1 mL / min, chromatographic column: AS18 anion analysis column, column temperature: 30°C, injection volume: 25 μL, qualitative determination is based on retention time, and quantitative determination is based on peak area. The standard working curve is drawn with chloride ion concentration as the horizontal axis and its peak area as the vertical axis.

[0047] (2) Sample testing: In a glove box (oxygen content: 0.39 ppm), accurately weigh 0.1013 g of tetrakis(triphenylphosphine) nickel sample using a ten-thousandth analytical balance into a 12 ml centrifuge tube. Seal the tube and remove it from the glove box. Add 5 ml of a 30 wt.% hydrogen peroxide solution and place it in an ultrasonic device for 5 min to ensure complete oxidation and decomposition of the product. Then, take 2 mL of the reaction solution, dilute it with 10 ml of ultrapure water, filter it with a 0.22 μm organic filter, and analyze the resulting pretreatment solution using ion chromatography. The calculated chloride ion content is 1.025%.

[0048] 3. Determination of Ni and Zn content in samples:

[0049] In a glove box (oxygen content: 0.36 ppm), 0.1003 g of tetrakis(triphenylphosphine)nickel sample was accurately weighed using a 10,000-ppm analytical balance into a 12 mL centrifuge tube. The tube was sealed and removed from the glove box. The sample was added to a microwave digestion vial and digested with a mixture of 5 mL of concentrated sulfuric acid and 5 mL of concentrated nitric acid. The Ni and Zn contents in the digestion solution were then analyzed by ICP-OES. The Zn and Ni contents were 0.816% and 5.288%, respectively.

[0050] 4. Calculation of the purity of tetrakis(triphenylphosphine)nickel:

[0051] ①Calculation of zinc chloride content: 0.816% / 65.38×136.28 = 1.701%

[0052] ② Chlorine consumption of zinc chloride is: 0.816% / 65.38×35.45×2 = 0.885%;

[0053] ③ Excess chlorine: 1.025%-0.885%=0.140%;

[0054] ④ Tris(triphenylphosphine)nickel chloride: 0.140% / 35.45×881 = 3.479%;

[0055] ⑤ Excess nickel is: 5.288% - 3.479% / 881×58.69 = 5.056%;

[0056] ⑥ Excess triphenylphosphine is: 92.871% - 3.479% / 881×262.285×3 = 89.763%;

[0057] ⑦The molar ratio of nickel to triphenylphosphine is: 89.763% / 262.285 / (5.056 / 58.69) = 3.973%;

[0058] The content of tris(triphenylphosphine) nickel is: (4-3.973%) / 4×3×100 = 2.100%;

[0059] Therefore, the purity of tetrakis(triphenylphosphine)nickel is: 1-2.100%-3.479%-1.701%=92.72%.

[0060] Example 2: Analysis of the content of tetrakis(triphenylphosphine)palladium:

[0061] 1. Determination of triphenylphosphine content in samples:

[0062] In a glove box (oxygen content: 0.34 ppm), accurately weigh 0.1012 g of tetrakis(triphenylphosphine)palladium sample using a 10,000-ppm analytical balance into a 12-ml centrifuge tube. The tube was sealed and removed from the glove box. Then, 7 ml of tetrahydrofuran and 3 ml of a 30 wt.% hydrogen peroxide solution were added to the tube. After reacting for 5 minutes, the reaction solution was filtered through a disposable filter to remove palladium oxide. A 2-ml sample of the filtrate was analyzed by liquid chromatography. The triphenylphosphine content was calculated based on a standard curve to be 98.956%.

[0063] 2. Determination of chloride ion content in samples:

[0064] In a glove box (oxygen content: 0.35 ppm), accurately weigh 0.1013 g of tetrakis(triphenylphosphine)palladium sample using a 10,000-ppm analytical balance into a 12 ml centrifuge tube. The tube was sealed and removed from the glove box. Add 5 ml of a 30 wt.% hydrogen peroxide solution and place in an ultrasonic device for 5 minutes to ensure complete oxidation and decomposition of the product. Then, a 2 ml sample of the reaction solution was diluted with 10 ml of ultrapure water and filtered through a 0.22 μm organic filter. The resulting pretreatment solution was analyzed by ion chromatography, and the calculated chloride ion content was 0.156%.

[0065] 3. Purity determination of tetrakis(triphenylphosphine)palladium:

[0066] ① Calculation of bis(triphenylphosphine)palladium chloride content: 0.156% / 35.45×701.90 = 3.09%

[0067] ② Calculation of the purity of tetrakis(triphenylphosphine)palladium: 98.956% - 3.09% = 95.86%.

[0068] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for determining the purity of a tetrakis(triphenylphosphine) complex, characterized in that: After the tetrakis(triphenylphosphine) complex is deeply oxidized with hydrogen peroxide, the contents of triphenylphosphine and impurity chloride ion therein are quantitatively determined respectively, thereby determining the chemical purity of the tetrakis(triphenylphosphine) complex; The structural formula of the tetrakis(triphenylphosphine) complex is [(C6H5)3P]4X, wherein X is a metal atom with a valence of zero, specifically tetrakis(triphenylphosphine)nickel, tetrakis(triphenylphosphine)palladium or tetrakis(triphenylphosphine)platinum; The method specifically comprises the following steps: 1) Determination of triphenylphosphine content The tetrakis(triphenylphosphine) complex to be tested is dissolved in an organic solvent, and then a 30 wt.% hydrogen peroxide solution is added to the resulting solution to completely oxidize the sample to form a mixed solution of triphenylphosphine oxide and a metal oxide; after filtering the metal oxide in the mixed solution, the content of triphenylphosphine oxide in the diluted reaction solution is measured by liquid chromatography, and the content of triphenylphosphine is converted to obtain the content of triphenylphosphine; 2) Determination of chloride ion content In an oxygen-free environment, a 30 wt.% hydrogen peroxide solution was added to the dried tetrakis(triphenylphosphine) complex to be tested, and the mixture was subjected to ultrasonication for 5 minutes. The solids were then removed by filtration. The filtrate was diluted with ultrapure water and filtered through a 0.22 μm organic filter to obtain a pretreatment solution. The chloride ion content in the pretreatment solution was then determined by ion chromatography. 3) Calculate the purity of the tetrakis(triphenylphosphine) complex based on the obtained substance content.

2. The method for determining the purity of tetrakis(triphenylphosphine) complex according to claim 1, wherein The amount of the organic solvent used in step 1) is calculated as 7 mL per 0.1 g of tetrakis(triphenylphosphine) complex; the organic solvent includes any one of tetrahydrofuran, acetonitrile, ethanol, and methanol.

3. The method for determining the purity of tetrakis(triphenylphosphine) complex according to claim 1, wherein The volume ratio of the organic solvent and the hydrogen peroxide solution used in step 1) is 7:

3.

4. The method for determining the purity of the tetrakis(triphenylphosphine) complex according to claim 1, wherein: The oxygen content of the oxygen-free environment in step 2) is less than 10 ppm.

5. The method for determining the purity of the tetrakis(triphenylphosphine) complex according to claim 1, wherein The amount of hydrogen peroxide solution used in step 2) is calculated as 5 mL per 0.1 g of tetrakis(triphenylphosphine) complex.

6. The method for determining the purity of the tetrakis(triphenylphosphine) complex according to claim 1, wherein The dilution multiple in step 2) is 10-30 times.

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