Coulomb method Karl Fischer reagent for aldehyde ketone moisture detection and preparation method of coulomb method Karl Fischer reagent

Abstract

The invention belongs to the field of chemical reagent moisture detection, and particularly relates to a coulometry Karl Fischer reagent for aldehyde ketone moisture detection and a preparation method of the coulometry Karl Fischer reagent. The coulometry Karl Fischer reagent for aldehyde ketone moisture detection is prepared from the following components in parts by weight: 1 to 15 percent of imidazole, 1 to 15 percent of 2-methylimidazole, 25 to 70 percent of ethylene glycol monomethyl ether, 5 to 30 percent of trichloromethane, 2 to 30 percent of trifluoroethanol, 2 to 10 percent of sulfur dioxide, 1 to 10 percent of methyl iodide, 0.1 to 5 percent of tetrabutylammonium iodide and 0.1 to 5 percent of iodine. The method does not contain hydroxyl compounds, effectively inhibits the generation of side reactions in detection, ensures the detection accuracy, and improves the product stability and effectively shortens the instrument equilibrium time by adding iodomethane and tetrabutylammonium iodide.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of water content detection of chemical reagents, and particularly relates to a coulometric Karl Fischer reagent for water content detection of aldehydes and ketones and a preparation method thereof. BACKGROUND

[0002] With the rapid development of science and technology, the purity and quality stability of various chemicals in high-end fields such as chemical industry, pharmaceutical industry, electronics and new energy have been put forward with unprecedented high standards. Among these requirements, the water content of the product as a crucial quality control index, its slight fluctuation may directly affect the chemical stability, catalytic activity, electrochemical performance and even the ultimate use safety and service life of the product. Therefore, the development of precise and reliable water detection technology and special reagents has become one of the core links of modern analytical chemistry and quality control.

[0003] Among the many water determination methods, the Karl Fischer method is established as the international standard method due to its high precision and good reproducibility. The method mainly includes two branches of volumetric method and coulometric method (electric quantity method). Among them, the Karl Fischer coulometric method can accurately determine the trace water content of ppm (parts per million) or even ppb (parts per billion) level due to its extremely high sensitivity, and plays an irreplaceable role in the fields of lithium ion battery electrolyte, high-end solvents, pharmaceutical intermediates and other extremely sensitive to water. In order to cope with complex and diverse sample matrix, the specialization and subdivision of Karl Fischer reagent have become the current main technical development trend. At present, the coulometric reagent on the market has developed from the early general type to the special type for specific applications, such as electrolyte special reagent with stronger anti-interference ability, and special reagent designed to solve the problem of aldehyde and ketone compound determination.

[0004] Although the development of special reagents has alleviated the detection difficulties in certain fields to some extent, the existing technology, especially the water determination technology for aldehyde ketone compounds, still has significant defects. Chinese Patent CN118671260A discloses a Karl Fischer reagent for coulometric determination of aldehyde ketone water and a preparation method thereof. The disclosed reagent formula contains hydrogen iodide, ethylene glycol methyl ether, chloroform, trifluoroethanol, imidazole, ethylimidazole, sulfur dioxide, iodine, and is used to improve the measurement accuracy. However, such advanced reagents usually rely on complex multi-component synergistic effects, and their preparation processes also tend to become cumbersome. For example, the patent method involves multiple precisely controlled gas introduction steps, which not only puts higher requirements on equipment, but also increases the difficulty of quality control and the risk of batch instability during the production process. In addition, the stability problems of multi-component reagents, potential environmental and operator health impacts, and higher use costs to some extent limit their large-scale industrial application. Therefore, the industry urgently needs a new solution that can ensure efficient and accurate determination of aldehyde ketone water while having a simple preparation process, good stability, and lower cost.

[0005] In addition, on the one hand, there are differences in the understanding of those skilled in the art; on the other hand, the inventors have studied a large number of literatures and patents when making the present invention, but due to the limited space, all the details and contents are not listed in detail. However, this does not mean that the present invention does not have these characteristics of the prior art, on the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art in the background art. SUMMARY

[0006] The present application belongs to the field of chemical reagent water detection, and particularly relates to a Karl Fischer reagent for coulometric determination of aldehyde ketone water and a preparation method thereof.

[0007] In view of the above technical problems, the present application aims to provide a Karl Fischer reagent for coulometric determination of aldehyde ketone water, which comprises the following components: imidazole 1-15%, 2-methylimidazole 1-15%, ethylene glycol methyl ether 25-70%, chloroform 5-30%, trifluoroethanol 2-30%, sulfur dioxide 2-10%, iodomethane 1-10%, tetrabutylammonium iodide 0.1-5%, and iodine 0.1-5% by mass fraction.

[0008] According to a preferred embodiment, the Karl Fischer reagent for coulometric determination of aldehyde ketone water comprises the following components: imidazole 2-14%, 2-methylimidazole 2-14%, ethylene glycol methyl ether 30-60%, chloroform 10-25%, trifluoroethanol 4-28%, sulfur dioxide 3-9%, iodomethane 2-9%, tetrabutylammonium iodide 0.2-4.5%, and iodine 0.2-4.5% by mass fraction.

[0009] According to a preferred embodiment, the Karl Fischer reagent for aldehyde ketone moisture detection by coulometry comprises the following components: imidazole 3%, 2-methylimidazole 4%, ethylene glycol methyl ether 50%, chloroform 15%, trifluoroethanol 15%, sulfur dioxide 8%, iodomethane 3%, tetrabutylammonium iodide 1%, iodine 1% by mass fraction.

[0010] The present application also aims to provide a preparation method of Karl Fischer reagent for aldehyde ketone moisture detection by coulometry, comprising the following steps: S1 mixing 1-15% imidazole, 1-15% 2-methylimidazole, 25-70% ethylene glycol methyl ether, 5-30% chloroform, and 2-30% trifluoroethanol by mass fraction; S2 bubbling 2-10% sulfur dioxide by mass fraction in an ice bath at 0-10℃; S3 adding 1-10% iodomethane, 0.1-5% tetrabutylammonium iodide, and 0.1-5% iodine by mass fraction to the mixed solution of S2 after bubbling.

[0011] According to a preferred embodiment, in S1, the imidazole is 2-14% by mass fraction, the 2-methylimidazole is 2-14% by mass fraction, the ethylene glycol methyl ether is 30-60% by mass fraction, the chloroform is 10-25% by mass fraction, and the trifluoroethanol is 4-28% by mass fraction.

[0012] According to a preferred embodiment, in S1, the imidazole is 3% by mass fraction, the 2-methylimidazole is 4% by mass fraction, the ethylene glycol methyl ether is 50% by mass fraction, the chloroform is 15% by mass fraction, and the trifluoroethanol is 15% by mass fraction.

[0013] According to a preferred embodiment, in S1, the mixed solution needs to be stirred until it is clear and transparent.

[0014] According to a preferred embodiment, in S2, the bubbling speed of sulfur dioxide gas is controlled at 200 mL / min.

[0015] According to a preferred embodiment, in S3, after all the ingredients are added and stirred to dissolve until the solution is clear and transparent, the solution is placed for not less than 24 h.

[0016] The present application also aims to provide the use of the Karl Fischer reagent for aldehyde ketone moisture detection by coulometry as described above or prepared by the preparation method of the Karl Fischer reagent for aldehyde ketone moisture detection by coulometry in detecting the moisture of a chemical containing an aldehyde ketone structure.

[0017] According to a preferred embodiment, the chemical containing an aldehyde ketone structure is a drug molecule or a synthetic intermediate thereof. For the synthesis of such drugs, the moisture content directly affects the crystal form, purity, and stability, and is a necessary item for drug quality control.

[0018] According to a preferred embodiment, the chemical containing aldehyde ketone structure is a high-performance solvent. Preferably, the chemical containing aldehyde ketone structure is electronic-grade propylene glycol methyl ether acetate (PMA), cyclohexanone.

[0019] According to a preferred embodiment, the chemical containing aldehyde ketone structure is a lithium ion battery electrolyte containing aldehyde ketone structure or producing aldehyde ketone after decomposition. Trace amount of water in the electrolyte can seriously damage the cycle life and safety of the battery. Therefore, accurate monitoring using aldehyde ketone special reagent can ensure that the water content in the electrolyte is within a controllable range.

[0020] The beneficial effects of the technical solution are: The coulometric Karl Fischer reagent formula for aldehyde ketone moisture detection uses tetrabutylammonium iodide and iodomethane as one of the sources of iodine, improves the stability of the product, and only needs to pass in sulfur dioxide gas, saving operation time and reducing operation risk. Tetrabutylammonium iodide can directly and efficiently release iodine anions (I - ) in the system, which is chemically stable, raw materials are easy to obtain and cost is low, which is beneficial to long-term storage and large-scale production of reagents. The introduction of iodomethane further optimizes the reagent system. It not only effectively enhances the solubility of iodine species and other components, ensures the uniformity and stability of the reaction system, but also captures trace amount of water remaining in the reagent through a specific mechanism, thereby reducing the background drift value of the reagent and providing a reliable basis for high-precision moisture determination.

[0021] Tetrabutylammonium iodide and iodomethane complement each other in function, synergize, and together create a measurement environment with suitable reaction activity, high storage stability, and low background signal. The formula realizes the dual goals of improving product reliability and optimizing production cost by simplifying the types of raw materials and process steps while ensuring accurate determination of the moisture content of aldehyde ketone samples. DETAILED DESCRIPTION

[0022] In the description of the present application, the terms are used only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0023] Unless otherwise specified, the test methods used in the following examples are conventional methods; the materials, reagents or instruments used are not specified by the manufacturer, and are reagents and materials available from commercial channels; if the specific conditions are not specified in the examples, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. Meanwhile, the present application does not limit the source of raw materials, and the raw materials used in the present application are ordinary commercially available products in the technical field, unless otherwise specified.

[0024] Example 1 This embodiment relates to a preparation method of a calfee solution reagent by the coulometric method.

[0025] The preparation method comprises the following steps: At room temperature, 20 g of imidazole, 20 g of 2-methylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added into a container and stirred to dissolve until clear and transparent; The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 50 g of iodomethane, 25 g of tetrabutylammonium iodide, and 15 g of iodine were added. After stirring and dissolving until clear and transparent, the solution was left to stand for 24 h to obtain the product.

[0026] Example 2 This embodiment relates to a preparation method of a calfee solution reagent by the coulometric method.

[0027] The preparation method comprises the following steps: At room temperature, 20 g of imidazole, 20 g of 2-methylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added into a container and stirred to dissolve until clear and transparent; The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 50 g of iodomethane, 25 g of tetrabutylammonium iodide, and 15 g of iodine were added. After stirring and dissolving until clear and transparent, the solution was left to stand for 24 h to obtain the product.

[0028] Example 3 This embodiment relates to a preparation method of a calfee solution reagent by the coulometric method.

[0029] The preparation method comprises the following steps: At room temperature, 20 g of imidazole, 20 g of 2-methylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added into a container and stirred to dissolve until clear and transparent; The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 50 g of iodomethane, 25 g of tetrabutylammonium iodide, and 15 g of iodine were added. After stirring and dissolving until clear and transparent, the solution was left to stand for 24 h to obtain the product.

[0030] Example 4 This embodiment relates to a preparation method of a calfee solution reagent by the coulometric method.

[0031] The preparation method comprises the following steps: At room temperature, 20 g of imidazole, 20 g of 2-methylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added into a container and stirred to dissolve until clear and transparent; The mixed solution is placed in an ice bath at 0-10°C, and 20 g of sulfur dioxide gas is slowly introduced, followed by the addition of 5 g of iodomethane, 5 g of tetrabutylammonium iodide, and 5 g of iodine. After stirring and dissolving until clear and transparent, the solution is left to stand for 24 h to obtain the product.

[0032] Example 4 This example relates to a method for preparing a calfenius reagent by the coulometric method.

[0033] The preparation method comprises the following steps: At room temperature, 75 g of imidazole, 5 g of 2-methylimidazole, 350 g of ethylene glycol methyl ether, 25 g of chloroform, and 10 g of trifluoroethanol are sequentially added to a container and stirred and dissolved until clear and transparent; The mixed solution is placed in an ice bath at 0-10°C, and 20 g of sulfur dioxide gas is slowly introduced, followed by the addition of 5 g of iodomethane, 5 g of tetrabutylammonium iodide, and 5 g of iodine. After stirring and dissolving until clear and transparent, the solution is left to stand for 24 h to obtain the product.

[0034] Example 5 This example relates to a method for preparing a calfenius reagent by the coulometric method.

[0035] The preparation method comprises the following steps: At room temperature, 75 g of imidazole, 5 g of 2-methylimidazole, 350 g of ethylene glycol methyl ether, 25 g of chloroform, and 10 g of trifluoroethanol are sequentially added to a container and stirred and dissolved until clear and transparent; The mixed solution is placed in an ice bath at 0-10°C, and 20 g of sulfur dioxide gas is slowly introduced, followed by the addition of 5 g of iodomethane, 5 g of tetrabutylammonium iodide, and 5 g of iodine. After stirring and dissolving until clear and transparent, the solution is left to stand for 24 h to obtain the product.

[0036] Comparative Example 1 The preparation method comprises the following steps: At room temperature, 75 g of imidazole, 5 g of 2-methylimidazole, 350 g of ethylene glycol methyl ether, 25 g of chloroform, and 10 g of trifluoroethanol are sequentially added to a container and stirred and dissolved until clear and transparent; The mixed solution is placed in an ice bath at 0-10°C, and 20 g of sulfur dioxide gas is slowly introduced, followed by the addition of 5 g of iodomethane, 5 g of tetrabutylammonium iodide, and 5 g of iodine. After stirring and dissolving until clear and transparent, the solution is left to stand for 24 h to obtain the product.

[0037] Comparative Example 2 The preparation method comprises the following steps: At room temperature, 75 g of imidazole, 5 g of 2-methylimidazole, 350 g of ethylene glycol methyl ether, 25 g of chloroform, and 10 g of trifluoroethanol are sequentially added to a container and stirred and dissolved until clear and transparent; The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 10 g of iodine and 30 g of hydrogen iodide were added, and the solution was stirred until it became clear and transparent. After 24 hours, the product was obtained.

[0038] Comparative Example 3 The preparation method included the following steps: At room temperature, 20 g of imidazole, 40 g of ethylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added to a container and stirred until the solution became clear and transparent. The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 10 g of iodine and 30 g of hydrogen iodide were added, and the solution was stirred until it became clear and transparent. After 24 hours, the product was obtained.

[0039] Comparative Example 4 The preparation method included the following steps: At room temperature, 20 g of imidazole, 40 g of ethylimidazole, 300 g of ethylene glycol methyl ether, 50 g of chloroform, and 50 g of trifluoroethanol were sequentially added to a container and stirred until the solution became clear and transparent. The mixed solution was placed in an ice bath at 0-10°C, and 40 g of sulfur dioxide gas was slowly introduced. Then, 10 g of iodine and 30 g of hydrogen iodide were added, and the solution was stirred until it became clear and transparent. After 24 hours, the product was obtained.

[0040] Test Example 1 Acetone was selected as the sample to be tested, and the moisture content was detected using Examples 1-3 and Comparative Examples 1-4, respectively.

[0041] The instrument used for detection was a Swiss Wescan Eco coulometric Karl Fischer moisture meter, with a default drift value of 30 ug / min. When the drift value was greater than 30 ug / min, the sample could not be detected. During detection, about 100 mL of coulometric Karl Fischer reagent for aldehyde and ketone moisture detection was added to the anode pool, and the same amount of reagent was added to the cathode. The sample size of acetone was 0.2 g each time, and the results are shown in Tables 1 and 2.

[0042] Table 1

[0043] Table 2

[0044] The sample size represents the mass of the sample (acetone in this case) taken for analysis each time. It is a known, precisely measured input value, which is the basis for calculating the moisture content in the sample. All subsequent calculations are based on this mass, and its accuracy directly determines the reliability of the final moisture content result.

[0045] The moisture content is the final target result of the test, representing the mass of water contained in the sample per million parts. This value directly reflects the absolute dryness of the sample and is a key indicator for evaluating product quality.

[0046] The drift value is the most important parameter for evaluating the background stability of the test system (mainly the reagent). It represents the amount of iodine (equivalent to water) consumed by the reagent in the electrolytic cell of the instrument per minute when no sample is introduced. The drift value is the background noise of this measurement method, and a low and stable drift value means that the reagent has little background interference and a high signal-to-noise ratio, so that the trace amount of water in the sample can be measured more accurately. In addition, a large drift value or a rapid and continuous increase in the drift value usually means that the reagent is unstable, has failed or has been contaminated by the environment (such as water intrusion from the air, sample side reactions, etc.).

[0047] As can be clearly seen from the data in Table 1, the aldehyde ketone moisture detection special Coulomb method Karl Fischer reagent developed in this study shows excellent performance in sample injection testing. The parallelism of each test result is good, all within the allowable error range (10 μg / min), and the reagent drift value rises slowly, showing good stability and supporting multiple sample determinations.

[0048] As can be seen from the experimental data provided in Table 2, the sample injection test results of the four comparative examples did not achieve the expected effect. Although each test result is still within the allowable error range (10 μg / min), the drift value rises significantly faster, reflecting the instability of the reagent system during the determination process and the continuous increase in background interference. This phenomenon directly leads to a significant reduction in the number of effective sample determinations, which cannot meet the requirements of reagent durability and stability in actual analysis. The comprehensive performance of the above comparative examples further highlights the significant advantages of the reagent formula described in this application in maintaining low drift and achieving multiple consecutive determinations.

[0049] In summary, Example 3 is a better solution, with an error range that can be further controlled to <5 μg / min, with higher determination accuracy.

[0050] It should be noted that the above-mentioned embodiments are examples, and those skilled in the art can think of various solutions under the inspiration of the disclosure of the present application, and these solutions also belong to the disclosed range of the present application and fall within the protection scope of the present application. Those skilled in the art should understand that the present application is illustrative and does not constitute a limitation on the claims. The protection scope of the present application is defined by the claims and their equivalents.

Claims

1. A coulometric Karl Fischer reagent for aldehyde ketone water detection, characterized by, Comprising the following components: by mass fraction, imidazole 1-15%, 2-methylimidazole 1-15%, ethylene glycol methyl ether 25-70%, chloroform 5-30%, trifluoroethanol 2-30%, sulfur dioxide 2-10%, iodomethane 1-10%, tetrabutylammonium iodide 0.1-5%, iodine 0.1-5%.

2. The Coulometric Karl Fischer reagent for aldehyde ketone water content detection according to claim 1, characterized by, Comprising the following components: by mass fraction, imidazole 2-14%, 2-methylimidazole 2-14%, ethylene glycol methyl ether 30-60%, chloroform 10-25%, trifluoroethanol 4-28%, sulfur dioxide 3-9%, iodomethane 2-9%, tetrabutylammonium iodide 0.2-4.5%, iodine 0.2-4.5%.

3. The calvet reagent for aldehyde / ketone water content measurement according to claim 1, characterized by, Comprising the following components: by mass fraction, imidazole 3%, 2-methylimidazole 4%, ethylene glycol methyl ether 50%, chloroform 15%, trifluoroethanol 15%, sulfur dioxide 8%, iodomethane 3%, tetrabutylammonium iodide 1%, iodine 1%.

4. A method for preparing a calconcarboxylic reagent for aldehyde ketone water content measurement, characterized by, Comprising the following steps: S1 mixing 1-15% imidazole, 1-15% 2-methylimidazole, 25-70% ethylene glycol methyl ether, 5-30% chloroform, 2-30% trifluoroethanol by mass fraction; S2 bubbling 2-10% sulfur dioxide by mass fraction in an ice bath at 0-10℃; S3 adding the mixed solution of S2 to 1-10% iodomethane, 0.1-5% tetrabutylammonium iodide and 0.1-5% iodine by mass fraction after bubbling.

5. The method for preparing a calvet reagent for aldehyde / ketone water content detection according to claim 4, characterized by, In S1, by mass fraction, imidazole 2-14%, 2-methylimidazole 2-14%, ethylene glycol methyl ether 30-60%, chloroform 10-25%, trifluoroethanol 4-28%.

6. The method for preparing a calvet reagent for aldehyde / ketone water content detection according to claim 4, characterized by, In S1, by mass fraction, imidazole 3%, 2-methylimidazole 4%, ethylene glycol methyl ether 50%, chloroform 15%, trifluoroethanol 15%.

7. The method for preparing a calvet reagent for aldehyde / ketone water content detection according to claim 4, characterized by, In S1, the mixed solution needs to be stirred until it is clear and transparent.

8. The preparation method of a calvetius reagent for aldehyde ketone water content detection according to claim 4, characterized in that, In S2, the bubbling speed of sulfur dioxide gas is controlled at 200 mL / min.

9. The preparation method of a calvetius reagent for aldehyde ketone water content detection according to claim 4, characterized in that, In S3, after adding all ingredients, stir to dissolve until clear and transparent, and then place for not less than 24 h.

10. Use of the aldehyde ketone water content detection coulometric Karl Fischer reagent prepared by the preparation method of the aldehyde ketone water content detection coulometric Karl Fischer reagent according to any one of claims 1-4 or 5-9 in detecting the water content of a chemical containing an aldehyde ketone structure.

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