Method for detecting phenylacetyl chloride and impurities thereof

Abstract

The present invention relates to the technical field of analytical chemistry, particularly to a phenylacetyl chloride and impurity detection method, which comprises: mixing and dissolving a sample to be detected and an organic solvent, mixing with a derivatization reagent and a catalyst after the dissolving, carrying out a derivatization reaction to obtain a derivatized solution, and concentrating to obtain a derivative sample; dissolving a derivative sample in the mobile phase to obtain a solution to be detected; preparing an impurity thionyl chloride derivative reference solution and a phenylacetyl chloride test solution according to the method; preparing an impurity phenylacetic acid reference substance solution; and performing high performance liquid chromatography analysis on the solution to be detected, recording a spectrogram, and calculating the actual content of phenylacetyl chloride. The Friedel-Crafts reaction derivatization-HPLC combined detection system is established for the first time, high-concentration phenylacetyl chloride can be detected, meanwhile, the main components of phenylacetyl chloride and the content of key impurities phenylacetic acid and thionyl chloride are analyzed, and the method is simple, efficient and low in cost.

Description

Technical Field

[0001] The present invention relates to the technical field of analytical chemistry, in particular to a method for detecting phenylacetyl chloride and its impurities. Background Art

[0002] As an important chemical raw material, phenylacetyl chloride plays an irreplaceable role in key areas such as pharmaceutical synthesis, pesticide preparation, and spice production. Its purity directly affects the efficiency of downstream reactions, and impurities can affect the quality of downstream products. The mainstream preparation process of phenylacetyl chloride in industrial production currently uses phenylacetic acid and thionyl chloride to undergo chlorination reaction at a certain temperature, followed by distillation and purification to purify the product. However, this process has significant limitations: when there is an excess of phenylacetic acid in the reaction system, unreacted phenylacetic acid will remain in the product as an impurity; if the amount of thionyl chloride used exceeds the standard, it will also form impurity components in the final product that are difficult to remove. Existing detection methods for phenylacetyl chloride impurities present the following challenges: Gas chromatography, a traditional method for detecting organic compounds, suffers from the high boiling point and poor thermal stability of phenylacetic acid, which can distort test data and damage chromatographic columns, leading to large errors in the detection of phenylacetyl chloride content. While liquid chromatography is suitable for analyzing thermally unstable compounds, thionyl chloride lacks UV absorption, making direct detection difficult using conventional UV-visible detectors. Complex derivatization techniques are required. Conventional derivatization methods lack selectivity: esterification derivatization involves both phenylacetic acid and phenylacetyl chloride, making it impossible to accurately distinguish their contents. Amidation derivatization using N,N-diisopropylethylenediamine is only suitable for detecting trace amounts of phenylacetyl chloride, and its sensitivity and selectivity are insufficient for the concentration range of impurities commonly encountered in industrial production.

[0003] Therefore, a new detection method is needed that can simultaneously detect phenylacetyl chloride and impurities. Summary of the Invention

[0004] The object of the present invention is to provide a method for detecting phenylacetyl chloride and its impurities, wherein the method can simultaneously detect the main component of phenylacetyl chloride and its key impurities.

[0005] The present invention provides a method for detecting phenylacetyl chloride and its impurities, comprising the following steps: S1. Dissolving the sample in dichloromethane, an organic solvent, and mixing the dissolved sample with a derivatization reagent, fluorobenzene, and a catalyst, aluminum chloride, to produce a derivatization solution, which is then concentrated to obtain a derivative sample; dissolving the derivative sample in a mobile phase of acetonitrile-water to obtain a test solution; S2. Prepare impurity phenylacetic acid reference solution, prepare impurity thionyl chloride derivative reference solution and phenylacetyl chloride test solution according to the method described in step S1; S3. Chromatographic column: octadecylsilane bonded silica gel column; mobile phase: acetonitrile-water solution, flow rate: 0.5-1.5 mL / min; detection wavelength: 240-260 nm; S4. Accurately measure the phenylacetic acid reference solution, the thionyl chloride derivative reference solution, and the phenylacetyl chloride test solution, respectively, and perform liquid chromatography analysis and record the spectra; Response curves were drawn based on the spectral data and concentrations of multiple phenylacetic acid reference solutions and thionyl chloride derivative reference solutions, and the spectral data of the phenylacetyl chloride test solution were substituted into the response curves to calculate the actual content of phenylacetyl chloride.

[0006] Preferably, the specific steps of step S1 include: mixing and dissolving the sample to be tested with an organic solvent, dichloromethane, adding a derivatization reagent, fluorobenzene, and starting an ice bath after dissolution, then adding a catalyst, aluminum chloride, to cause a derivatization reaction, then adding water to terminate the reaction, standing for 5-10 minutes to separate the layers, then separating the organic layer, and concentrating the organic layer to obtain a derivative sample; dissolving the derivative sample in a mobile phase to obtain a test solution, wherein the mobile phase is an acetonitrile aqueous solution.

[0007] Preferably, in step S1, the mass ratio of the organic solvent dichloromethane to the sample to be tested is (15-30):1.

[0008] Preferably, in step S1, the molar ratio of the sample to be tested: fluorobenzene: aluminum chloride during mixing is 1: (1-1.5): (1-1.1).

[0009] Preferably, the reaction temperature of the derivatization reaction in step S1 is 0-5°C, and the reaction time is 8-15 min.

[0010] Preferably, the volume ratio of acetonitrile to water in the mobile phase of step S1 and step S3 is 60:(35-45).

[0011] Preferably, the mass volume concentration of the derivative sample in the test solution in step S1 is 0.64-0.96 mg / mL.

[0012] Preferably, the detection wavelength of the high performance liquid chromatography analysis in step S3 is 248 nm.

[0013] Preferably, during the high performance liquid chromatography analysis in step S3, the column temperature of the C18 chromatographic column is 23-27°C.

[0014] Preferably, during the high performance liquid chromatography analysis in step S3, the injection volume is 10-20 μL.

[0015] Preferably, during the calculation in step S3, the purity of phenylacetic acid and thionyl chloride derivatives is calculated based on the liquid phase spectrum of the phenylacetyl chloride test solution, and the actual contents of phenylacetic acid and thionyl chloride are calculated based on the response curves of the phenylacetic acid and thionyl chloride derivatives, thereby obtaining the actual content of phenylacetyl chloride in the phenylacetyl chloride test sample.

[0016] Beneficial effects: The present invention uses fluorobenzene as a derivatization reagent. The phenylacetyl chloride to be detected and a quantitative amount of fluorobenzene undergo a Friedel-Crafts reaction under certain conditions. Phenylacetyl chloride, thionyl chloride and fluorobenzene generate corresponding derivatives, while phenylacetic acid does not react. The derivatives can stably exist during the detection process. High-performance liquid chromatography detection is then performed, and the spectrum is analyzed to quantitatively obtain the contents of the impurities thionyl chloride and phenylacetic acid, thereby determining the content of the phenylacetyl chloride.

[0017] The present invention establishes for the first time a Friedel-Crafts reaction derivatization-HLC coupled detection system, which can detect high-concentration phenylacetyl chloride and simultaneously analyze the contents of the main component of phenylacetyl chloride and its key impurities, phenylacetic acid and thionyl chloride, in the sample. The system is simple, efficient, and low-cost, and can comprehensively and accurately evaluate the quality of phenylacetyl chloride. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 chromatograms of thionyl chloride derivatives and phenylacetyl chloride derivatives in the examples of the present invention; Figure 2 This is the NMR image of the reference substance of thionyl chloride derivatives in the examples of the present invention; Figure 3 This is the NMR image of the reference substance of phenylacetyl chloride derivatives in the examples of the present invention; Figure 4 Response curve of phenylacetic acid in the embodiment of the present invention; Figure 5 Response curve of thionyl chloride derivatives in the examples of the present invention. DETAILED DESCRIPTION

[0019] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present application belongs.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular also includes the plural. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] The present invention provides a method for detecting phenylacetyl chloride and its impurities, wherein the impurities are phenylacetic acid and thionyl chloride. The detection method comprises the following steps: S1. The sample to be tested is mixed and dissolved with an organic solvent, dichloromethane, wherein the mass ratio of the organic solvent dichloromethane to the sample to be tested in the mixed solution is (15-30):1, and the concentration of the sample to be tested is preferably 0.05 g / mL. After dissolution, add the derivatization reagent fluorobenzene, start an ice bath, add the catalyst aluminum chloride at 0-5°C for a derivatization reaction for 8-15 minutes, the molar ratio of the sample phenylacetyl chloride: fluorobenzene: aluminum chloride is 1: (1-1.5): (1-1.1), the derivatization process adopts a shaking reaction, and then water is added to terminate the reaction to obtain a derivatized solution, which is allowed to stand for 5-10 minutes to separate the layers, and then the organic layer is separated and concentrated to obtain a derivative sample; In the derivatization reaction, both phenylacetyl chloride and thionyl chloride react with fluorobenzene. The reaction equation of phenylacetyl chloride and fluorobenzene is: ; The reaction equation of thionyl chloride and fluorobenzene is: ; The derivative sample is dissolved in a mobile phase to obtain a test solution. The mobile phase is an acetonitrile aqueous solution. The mobile phase is obtained by mixing acetonitrile and water in a volume ratio of 60:(35-45), and the preferred volume ratio of acetonitrile to water is 60:40.

[0023] S2. Preparation of impurity phenylacetic acid reference solution, according to the method described in step S1 to prepare impurity thionyl chloride derivative reference solution and phenylacetyl chloride test solution; phenylacetyl chloride derivative sample mass volume concentration of the test solution is 0.64-0.96 mg / mL; S3. HPLC conditions: Column: Octadecylsilane bonded silica gel column (250 mm × 4.6 mm × 5 µm or equivalent); Mobile phase: Acetonitrile in water, flow rate: 0.5-1.5 mL / min; Detection wavelength: 240-260 nm, preferably 248 nm; C18 column temperature: 23-27°C; Injection volume: 10-20 μL; S4. Accurately measure phenylacetic acid reference solution, thionyl chloride derivative reference solution and phenylacetyl chloride test solution, respectively, and perform liquid chromatography analysis and record the HPLC chromatogram; Response curves were drawn based on the chromatographic data and concentrations of multiple phenylacetic acid reference solutions and thionyl chloride derivative reference solutions. The purities of phenylacetic acid and thionyl chloride derivatives were calculated based on the liquid phase spectrum of the phenylacetyl chloride test solution. The actual contents of phenylacetic acid and thionyl chloride were calculated based on the response curves of the phenylacetic acid and thionyl chloride derivatives, and the actual content of phenylacetic acid and thionyl chloride in the phenylacetyl chloride test sample was then obtained (100% - phenylacetic acid% - thionyl chloride%).

[0024] The chromatogram of the phenylacetyl chloride sample after the above treatment contains thionyl chloride derivatives and phenylacetyl chloride derivatives is as follows Figure 1 shown.

[0025] The thionyl chloride derivative reference substance and the phenylacetyl chloride derivative reference substance treated in step S1 were subjected to nuclear magnetic resonance detection respectively, and the detection results were as follows: Figure 2 、 Figure 3 shown.

[0026] Example 1. Establishing an impurity response curve Sample pretreatment: Weigh 0.5 g of the phenylacetyl chloride sample to be tested and dissolve it in 10 mL of dichloromethane. After dissolution, add 0.45 mL of the derivatization reagent fluorobenzene. After ice bath, add 0.53 g of the catalyst aluminum chloride at 0-5°C and shake for 10 minutes. Then add water to terminate the reaction to obtain the derivatized solution. Let it stand for 5 minutes to separate the layers. Then separate the organic layer and concentrate the organic layer to dryness to obtain the derivative sample; The solution to be tested was tested using the high performance liquid chromatography area percentage method. The high performance liquid chromatography test conditions were as follows: Use C18 chromatographic column (250mm×4.6mm×5µm or equivalent), Mobile phase: acetonitrile and water volume ratio of 60:40, flow rate of 1 mL / min, column temperature of C18 column at 25 °C, The detection wavelength was 248 nm, the injection volume was 20 μL, and the spectrum was recorded.

[0027] Impurity 1. Phenylacetic acid According to the above-mentioned phenylacetyl chloride derivative detection method, phenylacetic acid linear solutions of different concentrations were prepared. The diluent was prepared by mixing acetonitrile and water in a volume ratio of 60:40. The solution preparation process is shown in Table 1.

[0028] Table 1

[0029] The phenylacetic acid linear solution was used for high performance liquid chromatography to obtain a spectrum. The purity of the phenylacetic acid chromatographic peak was measured and recorded using the area percentage method. The test data are shown in Table 2. A calibration curve method was used to plot a standard curve with the phenylacetic acid content as the abscissa and the phenylacetic acid purity as the ordinate. The fitted standard curve was: , ,like Figure 4 shown.

[0030] Table 2

[0031] Impurity 2. Thionyl chloride derivatives According to the above-mentioned phenylacetyl chloride derivative detection method, linear solutions of thionyl chloride derivatives of different concentrations were prepared. The diluent was prepared by mixing acetonitrile and water in a volume ratio of 60:40. The solution preparation process is shown in Table 3.

[0032] Table-3 Preparation of linear solutions of thionyl chloride derivatives

[0033] The above-mentioned thionyl chloride derivative linear solution was used for high performance liquid chromatography determination to obtain a spectrum. The area percentage method was used to measure and record the purity of the chromatographic peak of the thionyl chloride derivative. The calibration curve method was used with the thionyl chloride derivative content as the abscissa. The purity test data of the thionyl chloride derivative are shown in Table 4, and the fitting standard curve is: , ,like Figure 5 shown.

[0034] Table 4

[0035] Example 2: Sample detection Sample pretreatment: Weigh 0.5 g of the phenylacetyl chloride sample to be tested and dissolve it in 10 mL of dichloromethane. After dissolution, add 0.45 mL of the derivatization reagent fluorobenzene. After ice bath, add 0.53 g of the catalyst aluminum chloride at 0-5°C and shake for 10 minutes. Then add water to terminate the reaction to obtain the derivatized solution. Let it stand for 5 minutes to separate the layers. Then separate the organic layer and concentrate the organic layer to dryness to obtain the derivative sample; Preparation of test solution: Take 80 mg of the derivative sample in a 100 mL volumetric flask, mix acetonitrile and water in a volume ratio of 60:40 to prepare the mobile phase, ultrasonically dissolve the derivative sample in the mobile phase, dilute to the mark, and mix well to obtain the phenylacetyl chloride test solution; The phenylacetyl chloride test solution was tested by high performance liquid chromatography area percentage method. The high performance liquid chromatography test conditions were as follows: Use C18 chromatographic column (250mm×4.6mm×5µm or equivalent), Mobile phase: acetonitrile and water volume ratio of 60:40, flow rate of 1 mL / min, column temperature of C18 column at 25 °C, The detection wavelength is 248 nm, the injection volume is 20 μL, and the spectrum is recorded. According to the peak area percentages of thionyl chloride derivatives and phenylacetic acid in the detection spectrum and compared with the standard curve, the contents of thionyl chloride and phenylacetic acid are quantified, and then the content of phenylacetyl chloride is calculated.

[0036] Four groups of phenylacetyl chloride samples were tested, and the test results are shown in Table 5.

[0037] Table 5

[0038] Among them, the HPLC spectrum of the phenylacetyl chloride sample with sample batch number 003 is shown in Figure 1 .

[0039] Example 3: Method Validation Sample pretreatment: Weigh 0.5 g of the phenylacetyl chloride sample to be tested and dissolve it in 10 mL of dichloromethane. After dissolution, add 0.45 mL of the derivatization reagent fluorobenzene. After ice bath, add 0.53 g of the catalyst aluminum chloride at 0-5°C and shake for 10 minutes. Then add water to terminate the reaction to obtain the derivatized solution. Let it stand for 5 minutes to separate the layers. Then separate the organic layer and concentrate the organic layer to dryness to obtain the derivative sample; The solution to be tested was tested using the high performance liquid chromatography area percentage method. The high performance liquid chromatography test conditions were as follows: Use C18 chromatographic column (250mm×4.6mm×5µm or equivalent), Mobile phase: acetonitrile and water volume ratio of 60:40, flow rate of 1 mL / min, column temperature of C18 column at 25 °C, The detection wavelength was 248 nm, the injection volume was 20 μL, and the spectrum was recorded.

[0040] 1) Precision experiment The reproducible solution preparation process is shown in Table 6.

[0041] Table 6

[0042] The blank sample was used for testing, and the test results are shown in Table 7.

[0043] Table 7

[0044] The prepared repeatability solution was used for testing, and the test results are shown in Table 8.

[0045] Table 8

[0046] 2) Spike recovery The accuracy solution preparation process is shown in Table 9.

[0047] Table 9

[0048] The accuracy test was performed using the prepared solution, and the test results are shown in Table 10.

[0049] Table 10

[0050] 3) Limit of quantification (LOQ) / limit of detection (LOD) ① LOQ Each stock solution was gradually diluted to obtain the quantitative limit solution of each component (signal-to-noise ratio ≥ 10). Six injections were made continuously, the chromatograms were recorded, and the quantitative limit was calculated. The results are shown in Table 11.

[0051] Table 11

[0052] ② LOD The solution under the "LOQ" item was diluted to a low concentration solution and injected three times continuously. The detection limit of each component was obtained with a signal-to-noise ratio (S / N) ≥ 3. The detection limit results are shown in Table 12.

[0053] Table 12

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for detecting phenylacetyl chloride and its impurities, characterized in that, The following steps are involved: S1. Dissolving the sample in dichloromethane, an organic solvent, and mixing the dissolved sample with a derivatization reagent, fluorobenzene, and a catalyst, aluminum chloride, to produce a derivatization solution, which is then concentrated to obtain a derivative sample; dissolving the derivative sample in a mobile phase of acetonitrile-water to obtain a test solution; S2. Prepare impurity phenylacetic acid reference solution, prepare impurity thionyl chloride derivative reference solution and phenylacetyl chloride test solution according to the method described in step S1; S3. Chromatographic column: octadecylsilane bonded silica gel chromatographic column; Mobile phase: acetonitrile-water solution, flow rate: 0.5-1.5 mL / min; detection wavelength: 240-260 nm; S4. Accurately measure the phenylacetic acid reference solution, the thionyl chloride derivative reference solution, and the phenylacetyl chloride test solution, respectively, and perform liquid chromatography analysis and record the spectra; Response curves were drawn based on the spectral data and concentrations of multiple phenylacetic acid reference solutions and thionyl chloride derivative reference solutions, and the spectral data of the phenylacetyl chloride test solution were substituted into the response curves to calculate the actual content of phenylacetyl chloride.

2. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein The specific steps of step S1 include: mixing and dissolving the sample to be tested with an organic solvent, dichloromethane, adding a derivatization reagent, fluorobenzene, and starting an ice bath after dissolution, then adding a catalyst, aluminum chloride, to cause a derivatization reaction, then adding water to terminate the reaction, standing for 5-10 minutes to separate the layers, then separating the organic layer, and concentrating the organic layer to obtain a derivative sample; dissolving the derivative sample in a mobile phase to obtain a solution to be tested, wherein the mobile phase is an acetonitrile aqueous solution.

3. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein In step S1, the mass ratio of the organic solvent dichloromethane to the sample to be tested is (15-30):

1.

4. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein During the mixing in step S1, the molar ratio of the sample to be tested: fluorobenzene: aluminum trichloride is 1: (1-1.5): (1-1.1).

5. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein The reaction temperature of the derivatization reaction in step S1 is 0-5°C, and the reaction time is 8-15 minutes.

6. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein The volume ratio of acetonitrile to water in the mobile phase of step S1 is 60:(35-45).

7. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein The mass volume concentration of the derivative sample in the test solution in step S1 is 0.64-0.96 mg / mL.

8. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein The detection wavelength of the high performance liquid chromatography analysis in step S3 is 248 nm.

9. The method for detecting phenylacetyl chloride and impurities thereof according to claim 1, wherein During the high performance liquid chromatography analysis in step S3, the column temperature of the C18 chromatographic column is 23-27°C.

10. The method for detecting phenylacetyl chloride and its impurities according to claim 1, wherein: During the high performance liquid chromatography analysis in step S3, the injection volume is 10-20 μL.

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