Method for testing water content of organic peroxide and application of method

Abstract

The invention relates to a method for testing the water content of organic peroxide and application of the method, and the method comprises the following steps: mixing an organic peroxide sample and a reducing agent for reaction to obtain a reactant; testing the water content of the reactant and the water content of the reducing agent, and calculating the water content of the organic peroxide sample; the organic peroxide comprises any one of benzoyl peroxide or cumyl hydroperoxide or a combination of the benzoyl peroxide and the cumyl hydroperoxide; the reducing agent comprises a thioether compound. According to the method for testing the water content of the organic peroxide, the thioether compound is introduced as a reducing agent, deviation caused by the reaction of the organic peroxide and a Karl Fischer reagent during water content testing can be effectively avoided, high-precision and high-accuracy water content measurement is achieved, and the testing method is easy to operate and low in cost. And the practical value is high.

Description

Technical Field

[0001] The invention relates to the technical field of analysis and detection, and in particular to a method for testing the water content of an organic peroxide and an application thereof. Background Art

[0002] Karl Fischer titration is a widely used technique for determining moisture in analytical chemistry, known for its high accuracy and reliability. The core principle of the method is based on the quantitative chemical reaction of iodine with water: in anhydrous solvents, sulfur dioxide, iodine and water react quantitatively to produce hydrogen iodide and sulfuric acid. Karl Fischer reagents usually consist of iodine, sulfur dioxide and an organic base (such as pyridine or imidazole), dissolved in an appropriate solvent such as methanol. When the reagent comes into contact with the moisture in the sample, a quantitative reaction occurs, and the amount of iodine consumed is proportional to the moisture content. By measuring the iodine consumption by potentiometric titration or coulometric titration, the moisture content in the sample can be accurately calculated. Due to its high accuracy, easy operation and good result stability, the Karl Fischer method is widely used in quality control and research and development in the pharmaceutical, food, chemical and other industries.

[0003] However, the existing conventional Karl Fischer technique cannot directly measure the water content of organic peroxides, because organic peroxides will oxidize the iodine ions in the Karl Fischer system into iodine elemental substances to interfere with the titration process. The patent "A method for measuring trace water content in cumene hydrogen peroxide solution" (CN115356430A) adopts a method of first measuring the peroxide concentration, and then removing the peroxide in the system by accurate quantitative reduction with triphenylphosphine to measure the water content. Although the result of this method is relatively parallel, the operation steps are relatively cumbersome. At the same time, because triphenylphosphine will react rapidly with iodine elemental substances to generate triphenylphosphine iodide, a slight excess of triphenylphosphine will affect the accuracy of the results, so the experimental difficulty is relatively large. A low-temperature Karl Fischer moisture meter is designed in the patent "A method for measuring water in oxides" (CN112505242B), which effectively suppresses the redox reaction of peroxides and iodine ions by lowering the temperature of the reaction system, and improves the accuracy of the endpoint. The recovery rate of this method is between 95.0-102.4%, and the method is feasible. However, low temperature only reduces the reaction rate of peroxide and iodide ion, and does not fundamentally eliminate the problem. Low temperature will also lead to a decrease in the Karl Fischer reaction rate and electrode sensitivity. The cooling process will also prolong the pre-equilibrium time. At the same time, additional cooling devices will increase equipment costs and increase operational difficulty.

[0004] Therefore, it is necessary to develop a test method for the water content of organic peroxides to improve the precision and accuracy of the test and make it better used in daily testing. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for testing the water content of an organic peroxide and its application. The method for testing the water content of an organic peroxide provided by the present invention can effectively avoid the deviation caused by the reaction of the organic peroxide with the Karl Fischer reagent during the water content test by introducing a thioether compound as a reducing agent, thereby achieving high-precision and high-accuracy water content determination, and the test method is simple to operate and has high practical value.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0008] The organic peroxide sample and the reducing agent are mixed and reacted to obtain a reactant; the water content c2 of the reactant and the water content c1 of the reducing agent are tested to obtain the water content c of the organic peroxide sample, and the calculation formula is as follows:

[0009]

[0010] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample;

[0011] The organic peroxide includes any one of benzoyl peroxide or cumene hydroperoxide or a combination of the two;

[0012] The reducing agent includes a thioether compound.

[0013] Organic peroxides will react with iodine in the Karl Fischer system, so the water content cannot be tested directly. The present invention introduces thioether compounds as reducing agents, and performs water content testing after the peroxides are fully reduced by the thioether compounds. This method effectively avoids the influence of peroxides in the water content test, and the selection of such reducing agents, the reducing agents themselves and the substances generated by the reaction will not react with the Karl Fischer reagent, thereby ensuring the precision and accuracy of the test results. At the same time, the test method provided by the present invention is simple to operate, low in cost, can meet the needs of daily testing, and has high practicality.

[0014] Preferably, the thioether compound includes any one or a combination of at least two of methyl methylthioacetate, methyl phenyl sulfide, bis(4-hydroxy-3-tolyl) sulfide, 4-methoxythioanisole, dimethyl 3,3'-thiodipropionate or 1-methylthio-2-propanone.

[0015] Preferably, the thioether compound includes any one of methyl phenyl thioether, 4-methoxythioanisole or dimethyl 3,3'-thiodipropionate, or a combination of at least two thereof.

[0016] In the present invention, when methyl phenyl sulfide, 4-methoxythioanisole or dimethyl 3,3'-thiodipropionate is used, not only the precision and accuracy of the test can be improved, but also the efficiency of the test is significantly improved due to the shorter reaction time required, and the practicability is stronger.

[0017] Preferably, the organic peroxide sample is an organic peroxide or a solution obtained by dissolving an organic peroxide in a solvent.

[0018] Preferably, the solvent includes any one of butyl acetate, acetonitrile, ethanol or N,N-dimethylformamide, or a combination of at least two thereof.

[0019] Preferably, the molar ratio of the organic peroxide to the reducing agent in the organic peroxide sample is 1:(1.1-1.5) (for example, it may be 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, etc.).

[0020] In the present invention, it is not necessary to strictly control the amount of the reducing agent, and the detection effect of the present invention can be achieved when the reducing agent is in excess relative to the organic peroxide.

[0021] Preferably, the reaction temperature is 20-80°C (for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc.), and the reaction time is 5-60min (for example, 5min, 10min, 20min, 30min, 40min, 50min, 60min, etc.).

[0022] Preferably, the reaction temperature is 50-60° C., and the reaction time is 8-15 min.

[0023] In the present invention, when the reaction temperature is too low, the reaction speed is too slow. Within the preferred reaction temperature range of the present invention, the reaction time can be significantly shortened and the reaction efficiency can be improved.

[0024] Preferably, the water content is tested using the Karl Fischer volumetric method.

[0025] Preferably, the testing method comprises:

[0026] The organic peroxide sample and the reducing agent are mixed and reacted at 20-80° C. for 5-60 minutes to obtain a reactant; the water content c2 of the reactant and the water content c1 of the reducing agent are tested to obtain the water content c of the organic peroxide sample, and the calculation formula is as follows:

[0027]

[0028] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample;

[0029] The organic peroxide includes any one of benzoyl peroxide or cumene hydroperoxide or a combination of the two;

[0030] The reducing agent includes a thioether compound;

[0031] The molar ratio of the organic peroxide to the reducing agent in the organic peroxide sample is 1:(1.1-1.5).

[0032] In a second aspect, the present invention provides an application of the test method for water content of organic peroxides according to the first aspect in the research and development, production and detection of organic peroxides.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] The method for testing the water content of an organic peroxide provided by the present invention can effectively avoid the deviation caused by the reaction of the organic peroxide with the Karl Fischer reagent during the water content test by introducing a thioether compound as a reducing agent, thereby achieving high-precision and high-accuracy determination of the water content. The test method is simple to operate and has high practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the LC-MS spectrum in Example 1. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0037] Example 1

[0038] This embodiment provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0039] Mix and dissolve 30 g of organic peroxide (benzoyl peroxide) (the following are accurate to 0.0001 g) and 80 mL of butyl acetate to obtain an organic peroxide sample; take 1.5 g of the organic peroxide sample and 0.38 g of the reducing agent (dimethyl 3,3'-thiodipropionate) and place them in a sealed tube (the molar ratio of the organic peroxide to the reducing agent is 1:1.1, mix well, react at 55°C for 10 min, cool to 25°C, and use the Karl Fischer volumetric method to test the water content c2 of the reaction solution. At the same time, measure the water content c1 of the reducing agent to obtain the water content c of the organic peroxide sample. The calculation formula is as follows:

[0040]

[0041] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample.

[0042] The LC-MS spectra in Example 1 are as follows Figure 1 As shown, from top to bottom are the organic peroxide sample, 3,3'-dimethyl thiodipropionate standard and the mixed solution after the reaction. It can be seen that the organic peroxide has been fully reacted.

[0043] Example 2

[0044] This embodiment provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0045] 30 g of organic peroxide (benzoyl peroxide) (the following are accurate to 0.0001 g) and 80 mL of acetonitrile were mixed and dissolved to obtain an organic peroxide sample; 1.5 g of the organic peroxide sample and 0.31 g of the reducing agent (methyl phenyl sulfide) were placed in a sealed tube (the molar ratio of the organic peroxide to the reducing agent was 1:1.5, mixed, reacted at 50°C for 15 min, cooled to 25°C, and the water content c2 of the reaction solution was tested by Karl Fischer volumetric method, and the water content c1 of the reducing agent was measured at the same time to obtain the water content c of the organic peroxide sample, and the calculation formula was as follows:

[0046]

[0047] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample.

[0048] Example 3

[0049] This embodiment provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0050] 30 g of organic peroxide (isopropylbenzene hydroperoxide) (hereinafter all accurate to 0.0001 g) and 80 mL of ethanol were mixed and dissolved to obtain an organic peroxide sample; 1.5 g of the organic peroxide sample and 0.58 g of a reducing agent (4-methoxythioanisole) were placed in a sealed tube (the molar ratio of the organic peroxide to the reducing agent was 1:1.4, mixed well, reacted at 60° C. for 8 min, cooled to 25° C., and the water content c2 of the reaction solution was tested by Karl Fischer volumetric method, and the water content c1 of the reducing agent was measured at the same time to obtain the water content c of the organic peroxide sample, and the calculation formula was as follows:

[0051]

[0052] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample.

[0053] Example 4

[0054] This embodiment provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0055] Mix and dissolve 30 g of organic peroxide (benzoyl peroxide) (the following are accurate to 0.0001 g) and 80 mL of N,N-dimethylformamide to obtain an organic peroxide sample; take 1.5 g of the organic peroxide sample and 0.42 g of the reducing agent (3,3'-dimethyl thiodipropionate) and place them in a sealed tube (the molar ratio of the organic peroxide to the reducing agent is 1:1.2), mix them, react at 60°C for 8 minutes, cool to 25°C, and use the Karl Fischer volumetric method to test the water content c2 of the reaction solution. At the same time, measure the water content c1 of the reducing agent to obtain the water content c of the organic peroxide sample. The calculation formula is as follows:

[0056]

[0057] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample.

[0058] Example 5

[0059] This embodiment provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0060] Take 1.0g (the following are accurate to 0.0001g) of organic peroxide sample (isopropylbenzene hydroperoxide) and 1.2g of reducing agent (methyl phenyl sulfide) and place them in a sealed tube (the molar ratio of organic peroxide to reducing agent is 1:1.5, mix well, react at 45°C for 25min, cool to 25°C, and use Karl Fischer volumetric method to test the water content c2 of the reaction solution. At the same time, measure the water content c1 of the reducing agent to obtain the water content c of the organic peroxide sample. The calculation formula is as follows:

[0061]

[0062] Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample.

[0063] Example 6

[0064] This embodiment provides a method for testing the water content of an organic peroxide. The only difference between this method and Embodiment 1 is that the organic peroxide sample and the reducing agent are mixed and then reacted at 40° C. for 10 minutes. The other operations are similar to those of Embodiment 1.

[0065] Example 7

[0066] This embodiment provides a method for testing the water content of an organic peroxide, which differs from Embodiment 1 only in that the reducing agent is replaced with bis(4-hydroxy-3-tolyl)sulfide, and the reaction is carried out at 60° C. for 10 min. Other operations refer to Embodiment 1.

[0067] Example 8

[0068] This embodiment provides a method for testing the water content of an organic peroxide. The only difference between this method and Embodiment 1 is that the reducing agent is replaced by methyl methylthioacetate, and the reaction is carried out at 60° C. for 10 min. The other operations are the same as those of Embodiment 1.

[0069] Example 9

[0070] This embodiment provides a method for testing the water content of an organic peroxide, which differs from Embodiment 1 only in that the reducing agent is replaced by 1-methylthio-2-propanone, and the titrant is replaced by Karl Fischer aldehyde-ketone reagent. Other operations refer to Embodiment 1.

[0071] Comparative Example 1

[0072] This comparative example provides a method for testing the water content of an organic peroxide, which differs from Example 1 only in that the reducing agent is replaced by stannous chloride dihydrate, and other operations refer to Example 1.

[0073] Comparative Example 2

[0074] This comparative example provides a method for testing the water content of an organic peroxide, which differs from Example 1 only in that the reducing agent is replaced by triphenylphosphine, and other operations refer to Example 1.

[0075] Comparative Example 3

[0076] This comparative example provides a method for testing the water content of an organic peroxide, the testing method comprising:

[0077] Mix and dissolve 30 g (the following are accurate to 0.0001 g) of an organic peroxide (benzoyl peroxide) and 80 mL of butyl acetate to obtain an organic peroxide sample; take 1.5 g of the organic peroxide sample and directly test the water content by Karl Fischer volumetry.

[0078] Comparative Example 4

[0079] This embodiment provides a method for testing the water content of an organic peroxide. The only difference between this method and Embodiment 1 is that the reducing agent is replaced with dimethyl 3,3'-dithiodipropionate, and the reaction is carried out at 60°C for 60 minutes. The other operations are similar to those of Embodiment 1.

[0080] Test Example 1

[0081] Precision test

[0082] The water content of the organic peroxide samples was measured using the test methods provided in the above embodiments and comparative examples. The results are shown in Table 1.

[0083] Table 1

[0084] Grouping Number of measurements Average water content (%) RSD(%) Example 1 6 0.549 1.030 Example 2 6 0.587 1.124 Example 3 6 0.734 1.057 Example 4 6 0.659 1.349 Example 5 6 0.084 2.517 Example 6 6 0.059 7.124 Example 7 6 0.102 6.792 Example 8 6 0.541 1.218 Example 9 6 0.401 2.974 Comparative Example 1 6 - - Comparative Example 2 6 - - Comparative Example 3 6 - - Comparative Example 4 6 - -

[0085] Test Example 2

[0086] Accuracy test

[0087] The recovery rate of benzoyl peroxide acetonitrile solution with known water content was determined by the test method provided in the above embodiment and comparative example. The test method is as follows: 9 portions of benzoyl peroxide acetonitrile solution with a water content of 0.547% were taken, and water of different known masses was added respectively, and then the water content of the sample after adding water was tested, the spiked recovery rate was calculated, the average value was taken, and the RSD was calculated, which is summarized as shown in Table 2.

[0088] Table 2

[0089] Grouping Number of measurements Average recovery rate (%) RSD(%) Example 1 9 100.63 1.97 Example 2 9 102.34 2.34 Example 3 9 99.09 2.10 Example 4 9 102.05 2.49 Example 5 9 98.37 2.24 Example 6 9 - - Example 7 9 - - Example 8 9 101.81 2.28 Example 9 9 96.15 3.67 Comparative Example 1 9 - - Comparative Example 2 9 - - Comparative Example 3 9 - - Comparative Example 4 9 - -

[0090] From the test results in Table 1 and Table 2, we can see that:

[0091] (1) It can be seen from Examples 1 to 9 that the present invention uses thioether compounds as reducing agents for organic peroxides. During the reaction, neither the reactants nor the products react with the iodine in the Karl Fischer reagent, thereby avoiding the result deviation caused by the oxidation of iodine ions by organic peroxides, and in the preferred embodiment, higher precision and accuracy can be achieved.

[0092] (2) By comparing Example 1 and Example 6, it can be seen that when the reaction temperature is low and the reaction time is short, the organic peroxide fails to react completely, over-titration occurs, the precision decreases, and the accuracy test cannot be performed;

[0093] By comparing Example 1 and Example 7, it can be seen that when bis(4-hydroxy-3-tolyl) sulfide is used as a reducing agent, the reaction rate of the organic peroxide is slow, and because bis(4-hydroxy-3-tolyl) sulfide is a solid, the system after the reaction is two-phase, the precision of the water content test is reduced, and the accuracy test cannot be performed;

[0094] By comparing Example 1 and Example 8, it can be seen that when methyl methylthioacetate is used as the reducing agent, the effect is similar to that of dimethyl 3,3'-thiodipropionate;

[0095] By comparing Example 1 and Example 9, it can be seen that when 1-methylthio-2-propanone is used as a reducing agent, the carbonyl group present therein easily reacts with the methanol in the Karl Fischer reagent, making it difficult to reach the titration endpoint in the water test, and a special Karl Fischer titrant for aldehydes and ketones needs to be used for the test, but the test precision and accuracy are lower than those of Examples 1-5.

[0096] (3) By comparing Example 1 with Comparative Examples 1-3, it can be seen that when stannous chloride dihydrate or triphenylphosphine is used as a reducing agent or the water content of the organic peroxide sample is directly measured, because the above substances will react with the iodine in the Karl Fischer reagent, the result is too high and affects the endpoint determination, so it is impossible to perform a precise and accurate test of the water content.

[0097] By comparing Example 1 with Comparative Example 4, it can be seen that when dimethyl 3,3'-dithiodipropionate is used as a reducing agent to measure the water content of an organic peroxide sample, the water content cannot be precisely and accurately tested because the substance hardly reacts with the organic peroxide sample.

[0098] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for testing the water content of an organic peroxide, characterized in that: The test method includes: The organic peroxide sample and the reducing agent are mixed and reacted to obtain a reactant; the water content c2 of the reactant and the water content c1 of the reducing agent are tested to obtain the water content c of the organic peroxide sample, and the calculation formula is as follows: Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample; The organic peroxide includes any one of benzoyl peroxide or cumene hydroperoxide or a combination of the two; The reducing agent includes a thioether compound.

2. The testing method according to claim 1, characterized in that: The thioether compound includes any one of methyl thioacetate, methyl phenyl thioether, 4-methoxythioanisole, bis(4-hydroxy-3-tolyl) sulfide, dimethyl 3,3'-thiodipropionate or 1-methylthio-2-propanone, or a combination of at least two thereof.

3. The testing method according to claim 2, characterized in that: The thioether compound includes any one of methyl phenyl thioether, 4-methoxythioanisole or dimethyl 3,3'-thiodipropionate, or a combination of at least two thereof.

4. The testing method according to any one of claims 1 to 3, characterized in that: The organic peroxide sample is an organic peroxide or a solution obtained by dissolving an organic peroxide in a solvent.

5. The testing method according to claim 4, characterized in that: The solvent includes any one of butyl acetate, acetonitrile, ethanol or N,N-dimethylformamide or a combination of at least two thereof.

6. The testing method according to any one of claims 1 to 5, characterized in that: The molar ratio of the organic peroxide to the reducing agent in the organic peroxide sample is 1:(1.1-1.5).

7. The testing method according to any one of claims 1 to 6, characterized in that: The reaction temperature is 20-80°C, and the reaction time is 5-60min; Preferably, the reaction temperature is 50-60° C., and the reaction time is 8-15 min.

8. The testing method according to any one of claims 1 to 7, characterized in that: The water content was tested using the Karl Fischer volumetric method.

9. The testing method according to any one of claims 1 to 8, characterized in that: The test method includes: The organic peroxide sample and the reducing agent are mixed and reacted at 20-80° C. for 5-60 minutes to obtain a reactant; the water content c2 of the reactant and the water content c1 of the reducing agent are tested to obtain the water content c of the organic peroxide sample, and the calculation formula is as follows: Wherein, m1 is the mass of the reducing agent, and m is the mass of the organic peroxide sample; The organic peroxide includes any one of benzoyl peroxide or cumene hydroperoxide or a combination of the two; The reducing agent includes a thioether compound; The molar ratio of the organic peroxide to the reducing agent in the organic peroxide sample is 1:(1.1-1.5).

10. Application of the method for testing the water content of an organic peroxide according to any one of claims 1 to 9 in the research and development, production and detection of organic peroxides.

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