Karl Fischer reagent for anisole moisture detection and preparation method thereof

Abstract

The invention provides a Karl-Fischer reagent for anisole moisture detection and a preparation method thereof, and the Karl-Fischer reagent comprises the following components by mass: 2-6% of iodine, 8-12% of sulfur dioxide, 70-80% of an ether solvent, and 10-20% of an alkaline buffer agent. The solvent of the Karl Fischer reagent is an ether solvent, and an alkaline buffer agent is added, so that interference of peroxide in anisole can be effectively avoided, and the accuracy of anisole moisture detection is ensured; moreover, the Karl Fischer reagent does not contain toxic and environment-polluting components such as methanol, pyridine and the like, and is safer and more environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of boron isotope separation, in particular to a complexing agent anisole used for boron isotope chemical exchange separation, and in particular to a Karl Fischer reagent for anisole moisture detection and a preparation method thereof. Background Art

[0002] Stable isotope boron-10 ( 10 B) Due to its unique neutron absorption characteristics, it is increasingly used in modern nuclear industry, military equipment and medicine. 10 B products include boron-10 acid, boron-10 powder, boron carbide, boron nitride and other products with different abundance requirements. The industrial chain is long and the product application fields are wide, especially playing an important role in alleviating the global petrochemical energy shortage. The application of such products in the nuclear energy field makes it possible to widely develop and apply economic, safe and clean nuclear energy resources.

[0003] Since the isotope boron-10 has a much larger thermal neutron capture area than boron-11, it is widely used in the nuclear industry to manufacture thermal neutron counters, reactor control rods and thermal neutron shielding materials, especially in boron neutron cancer treatment methods (BNCT). The abundance of boron-10 in nature is only 19-20%, so it is necessary to enrich and purify the boron-10 isotope.

[0004] The chemical exchange distillation method of boron trifluoride anisole is a process technology first invented in the United States. It started in the mid-1970s and reached full production in 1977 with a production scale of 2 tons / year, and the boron-10 abundance can reach 92%. This process technology has advantages because it operates under normal temperature and pressure conditions and has a higher separation coefficient. Although the process of preparing anisole complex from raw materials is slightly longer than that of methyl and ethyl ether complex materials, its basic material anisole is recycled throughout the production system, and the final product is enriched boron trifluoride-10 ( 10 BF 3 ) and boron trifluoride-11( 11 BF 3 ), both of which are high value-added terminal technology products, in terms of cost and benefit accounting, compared with the methyl ether method, ethyl ether method has obvious advantages, making the production cost much lower. Currently, the United States and Georgia both use this process technology route.

[0005] Anisole is an important raw material, intermediate and solvent, and is widely used in the fields of drug synthesis, dye synthesis, and spice blending. The water content of industrial-grade anisole is relatively low, generally between 100 and 500 ppm. As the object to be separated, the raw material of isotope boron-10 and isotope boron-11, boron trifluoride gas, is very easy to react with water, and the hydrofluoric acid produced is extremely corrosive and violently exothermic. The by-products are also easy to clog the pipeline, reducing the heat exchange efficiency and transportation efficiency. Therefore, when anisole is used in the chemical exchange distillation method of boron trifluoride anisole to achieve boron isotope separation, it is necessary to further perform deep dehydration. It is generally believed that the water content needs to be reduced to below 30 ppm, or even below 10 ppm, so as to ensure production safety, extend the service life of equipment, reduce the generation of by-products, and improve production efficiency.

[0006] In the process of industrial production of anisole, phenol or methylating agent may be present due to incomplete reaction or by-products. During long-term storage, peroxide is easily formed due to contact with air and light. Its presence will cause the stability of anisole to further decrease and form more peroxide, thereby interfering with the results of some analytical tests.

[0007] At present, the most commonly used method for the detection of trace water is the Karl Fischer coulometric titration method, but it requires that the Karl Fischer reagent used in the test has no effect on the sample to be tested to ensure the accuracy of the test results. Currently, the Karl Fischer reagents on the market are mainly divided into two categories. One is an open reagent, which is mainly used for the detection of organic solvents containing hydroxyls, such as methanol, ethanol, etc., but this type of reagent is not accurate and reliable when testing anisole containing impurities such as peroxides; the other type is a special reagent for aldehydes and ketones, which cannot be used for the determination of moisture in other substances, and therefore cannot be used for the detection of moisture in anisole.

[0008] In summary, it is necessary to develop a Karl Fischer reagent for detecting the moisture content of anisole and a preparation method thereof. Summary of the invention

[0009] In view of the problems existing in the prior art, mainly aiming at the problem that the Karl Fischer reagent in the prior art cannot be applied to the water content detection of industrial anisole, especially the interference of peroxide in industrial anisole cannot be avoided. The present invention provides a Karl Fischer reagent for the water content detection of anisole and a preparation method thereof. The solvent of the Karl Fischer reagent is an ether solvent, and an alkaline buffer is added, which can effectively avoid the interference of peroxide in anisole and ensure the accuracy of the water content detection of anisole. Moreover, the Karl Fischer reagent of the present invention does not contain toxic and environmentally polluting components such as methanol and pyridine, and is safer and more environmentally friendly.

[0010] To achieve this object, the present invention adopts the following technical solutions:

[0011] One of the purposes of the present invention is to provide a Karl Fischer reagent for detecting the moisture content of anisole, which comprises the following components according to the mass percentage: 2-6% iodine, 8-12% sulfur dioxide, 70-80% ether solvent and 10-20% alkaline buffer.

[0012] The solvent of the Karl Fischer reagent of the present invention is an ether solvent, and an alkaline buffer is added, which can effectively avoid the interference of peroxide in anisole and ensure the accuracy of anisole water detection; moreover, the Karl Fischer reagent of the present invention does not contain toxic and environmentally polluting components such as methanol and pyridine, and is safer and more environmentally friendly.

[0013] In the Karl Fischer reagent for detecting moisture in anisole of the present invention, the content of iodine is 2-6% by mass, for example, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5% or 6%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0014] In the Karl Fischer reagent for detecting moisture in anisole of the present invention, sulfur dioxide is 8-12% by mass, for example, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5% or 12%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0015] In the Karl Fischer reagent for detecting moisture in anisole of the present invention, the ether solvent is 70-80% by mass, for example, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79% or 80%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0016] In the Karl Fischer reagent for detecting moisture in anisole of the present invention, the alkaline buffer contains 10-20% by mass, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0017] As a preferred technical solution of the present invention, the following components are included according to mass percentage: iodine 2-6%, sulfur dioxide 8-12%, ether solvent 72-77%, and alkaline buffer 12-17%.

[0018] As a preferred technical solution of the present invention, the composition is composed of the following components according to mass percentage: 4% iodine, 10% sulfur dioxide, 72% ether solvent and 14% alkaline buffer.

[0019] As a preferred technical solution of the present invention, the ether solvent includes any one of diethyl ether, ethyl butyl ether, and dibutyl ether, or a combination of at least two of them.

[0020] It should be noted that the present invention uses ether solvents, preferably diethyl ether, which can not only fully dissolve iodine, sulfur dioxide, and alkaline buffer, but also has a polarity extremely close to that of anisole at room temperature, ensuring that the analyte and Karl Fischer reagent are fully miscible, which is more conducive to the test reaction.

[0021] As a preferred technical solution of the present invention, the alkaline buffer comprises triethylamine and / or N-methylpyrrolidine.

[0022] It should be noted that commercially available Karl Fischer reagent uses pyridine or imidazoles as alkaline buffer, but pyridine or imidazoles contain 1 to 2 nitrogen atoms, have certain alkalinity and reducibility, and impurities in anisole include peroxide, and peroxide has oxidizing property, and when the peroxide bond in peroxide breaks, the nitrogen atom of pyridine or imidazole can be oxidized, therefore, commercially available Karl Fischer reagent often cannot avoid the interference of peroxide in industrial anisole. In contrast, although triethylamine and N-methylpyrrolidine also have nitrogen atoms that provide alkalinity, under detection conditions, nitrogen atoms cannot react with peroxide, because the oxidation reaction usually needs to have reactive hydrogen or unsaturated bonds and other reaction sites, and triethylamine and N-methylpyrrolidine just do not have these sites that are easily attacked. Therefore, Karl Fischer reagent of the present invention will not be subject to any interference of peroxide in anisole, and is particularly suitable for detecting the water content of industrial anisole.

[0023] A second object of the present invention is to provide a method for preparing the Karl Fischer reagent for detecting anisole water content as described in one of the objects, the preparation method comprising the following steps:

[0024] (1) uniformly mixing an ether solvent and an alkaline buffer according to a target mass percentage to obtain a first mixed solution;

[0025] (2) introducing sulfur dioxide into the first mixed solution of step (1) and stirring the mixture to obtain a second mixed solution;

[0026] (3) adding iodine to the second mixed solution of step (2), stirring until all dissolved, sealing and placing, to obtain Karl Fischer reagent for anisole water content detection.

[0027] As a preferred technical solution of the present invention, in step (1), the ether solvent and the alkaline buffer are dried and have a water content of less than 100 ppm. A room temperature oil bath is used for mixing, and the temperature is controlled to be 15-25°C, for example, 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, 21°C, 22°C, 23°C, 24°C or 25°C, etc., but are not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0028] As a preferred technical solution of the present invention, the sulfur dioxide in step (2) is sulfur dioxide gas. Before the sulfur dioxide gas is introduced, the container containing the first mixed solution is evacuated to control the vacuum degree below 0.1 atm.

[0029] As a preferred technical solution of the present invention, the sulfur dioxide gas is dehydrated by concentrated sulfuric acid.

[0030] As a preferred technical solution of the present invention, the sealing placement time in step (3) is 20-28h, for example 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h or 28h, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0032] (1) The solvent of the Karl Fischer reagent of the present invention is an ether solvent, and an alkaline buffer is added, which can effectively avoid the interference of peroxide in anisole and ensure the accuracy of anisole water detection;

[0033] (2) The Karl Fischer reagent of the present invention does not contain toxic and environmentally polluting components such as methanol and pyridine, and is safer and more environmentally friendly. DETAILED DESCRIPTION

[0034] For the convenience of understanding the present invention, the present invention lists the following embodiments. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0035] Example 1

[0036] The present embodiment provides a Karl Fischer reagent for detecting moisture in anisole and a preparation method thereof. The Karl Fischer reagent for detecting moisture in anisole is composed of the following components in terms of mass percentage: 4% iodine, 10% sulfur dioxide, 72% ether, and 14% triethylamine;

[0037] The preparation method comprises the following steps:

[0038] (1) Under room temperature and humidity below 40%, a flat-bottomed three-necked flask was used, and the temperature was controlled at 20°C in an oil bath at room temperature. Magnetic stirring was continued, and the three-necked flask was connected to a constant pressure funnel and a vacuum port respectively;

[0039] According to the target mass percentage, 72 g of ether and 14 g of triethylamine were added into the idle mouth of the three-necked flask in sequence, and the mouth of the flask was sealed with a glass stopper to obtain a first mixed solution;

[0040] (2) The gas extraction port is opened, and the gas in the bottle is extracted using a diaphragm vacuum pump. After the vacuum degree reaches 0.1 atm, the gas cylinder switch is turned on. The 10 g of sulfur dioxide gas in the gas cylinder will gradually dissolve in the first mixed solution with magnetic stirring. After 2 hours, the gas cylinder is purged with dry nitrogen for 30 minutes to allow the sulfur dioxide to react completely to obtain a second mixed solution.

[0041] (3) Add 4 g of elemental iodine to the second mixed solution, stir until it is completely dissolved, seal and place for 24 hours to obtain Karl Fischer reagent for anisole water content detection.

[0042] Example 2

[0043] The present embodiment provides a Karl Fischer reagent for detecting moisture content of anisole and a preparation method thereof. The Karl Fischer reagent for detecting moisture content of anisole is composed of the following components in terms of mass percentage: 4% iodine, 10% sulfur dioxide, 70% ether, and 16% N-methylpyrrolidine;

[0044] The preparation method comprises the following steps:

[0045] (1) Under room temperature and humidity below 40%, a flat-bottomed three-necked flask was used, and the temperature was controlled at 20°C in an oil bath at room temperature. Magnetic stirring was continued, and the three-necked flask was connected to a constant pressure funnel and a vacuum port respectively;

[0046] According to the target mass percentage, 70 g of ether and 16 g of N-methylpyrrolidine were added into the idle mouth of the three-necked flask in sequence, and the mouth of the flask was sealed with a glass stopper to obtain a first mixed solution;

[0047] (2) The gas extraction port is opened, and the gas in the bottle is extracted using a diaphragm vacuum pump. After the vacuum degree reaches 0.1 atm, the gas cylinder switch is turned on. The 10 g of sulfur dioxide gas in the gas cylinder will gradually dissolve in the first mixed solution with magnetic stirring. After 2 hours, the gas cylinder is purged with dry nitrogen for 30 minutes to complete the reaction of sulfur dioxide, thereby obtaining a second mixed solution.

[0048] (3) Add 4 g of elemental iodine to the second mixed solution, stir until it is completely dissolved, seal and place for 24 hours to obtain Karl Fischer reagent for anisole water content detection.

[0049] Comparative Example 1

[0050] This comparative example provides a Karl Fischer reagent and a preparation method thereof. Compared with Example 1, the only difference is that diethyl ether is replaced by an equal mass of methanol.

[0051] Comparative Example 2

[0052] This comparative example provides a commercially available Karl Fischer reagent, which uses pyridine or imidazole as an alkaline buffer. The specific information is: brand Honeywell / Fluka, Cat.34836-500ML-CN, batch number N0940, material number 10657366.

[0053] Since the present invention is directed to anisole, a complexing agent used for boron isotope chemical exchange separation, it is generally believed that the water content needs to be reduced to below 30 ppm, or even below 10 ppm. However, the water content of industrial-grade anisole is generally between 100 and 500 ppm, and the prior art does not disclose an accurate and effective detection method, so the present invention uses a method of adding a known amount of deionized water to determine the accuracy of the Karl Fischer reagent. The specific detection method is: dehydrating the purchased industrial-grade anisole to different degrees to obtain anisole samples with gradually reduced water content, taking a certain anisole sample and using Karl Fischer coulometric titration to detect the water content, specifically using Swiss Metrohm 831 coulometric Karl Fischer moisture meter to test, and obtaining a first measurement result C 1 Then take the same anisole sample and add a known amount of deionized water to obtain the theoretical result C 理论 Repeat the same test operation to get the second test result C after adding water. 2 , further add a known amount of benzoyl peroxide to the anisole after adding water, repeat the same detection operation, and the third test result C after adding peroxide can be obtained. 3 By comparison, it can be determined whether the Karl Fischer reagent will be affected by peroxide, and then whether the Karl Fischer reagent can meet the requirements of anisole moisture detection. The specific test results are shown in Table 1.

[0054] Table 1

[0055]

[0056]

[0057] It can be seen from the test results in Table 1 that compared with the Karl Fischer reagents described in Comparative Examples 1 and 2, the Karl Fischer reagent of the present invention not only has a theoretical result C 理论 The second test result after adding water C 2 The difference is small. After adding benzoyl peroxide, the second test result after adding water is C2 The third test result after adding peroxide C 3 The phase difference is still small, indicating that the Karl Fischer reagent of the present invention will not be affected by peroxide, has higher detection accuracy, stronger anti-interference ability, and can meet the requirements of anisole moisture detection.

[0058] In summary, the solvent of the Karl Fischer reagent of the present invention is an ether solvent, and an alkaline buffer is added, which can effectively avoid the interference of peroxide in anisole and ensure the accuracy of anisole water detection; moreover, the Karl Fischer reagent of the present invention does not contain toxic and environmentally polluting components such as methanol and pyridine, and is safer and more environmentally friendly.

[0059] The present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A Karl Fischer reagent for detecting water content of anisole, characterized in that, Calculated by mass percentage, the composition includes: 2-6% iodine, 8-12% sulfur dioxide, 70-80% ether solvent and 10-20% alkaline buffer.

2. the Karl Fischer reagent for detecting the moisture content of anisole according to claim 1, is characterized in that, Calculated by mass percentage, the composition includes: 2-6% iodine, 8-12% sulfur dioxide, 72-77% ether solvent and 12-17% alkaline buffer.

3. anisole water content detection Karl Fischer reagent according to claim 2, is characterized in that, Calculated by weight percentage, it is composed of the following components: 4% iodine, 10% sulfur dioxide, 72% ether solvent, and 14% alkaline buffer.

4. according to the Karl Fischer reagent for detecting the moisture content of anisole according to any one of claims 1 to 3, it is characterized in that, The ether solvent includes any one of diethyl ether, ethyl butyl ether and dibutyl ether, or a combination of at least two of them.

5. according to the Karl Fischer reagent for detecting the moisture content of anisole according to any one of claims 1 to 3, it is characterized in that, The alkaline buffer includes triethylamine and / or N-methylpyrrolidine.

6. A method for preparing the Karl Fischer reagent for detecting the moisture content of anisole according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) uniformly mixing an ether solvent and an alkaline buffer according to a target mass percentage to obtain a first mixed solution; (2) introducing sulfur dioxide into the first mixed solution of step (1) and stirring the mixture to obtain a second mixed solution; (3) adding iodine to the second mixed solution of step (2), stirring until all dissolved, sealing and placing, to obtain Karl Fischer reagent for anisole water content detection.

7. The preparation method according to claim 6, characterized in that: In step (1), the ether solvent and alkaline buffer are dried to have a water content of less than 100 ppm. When mixing, an oil bath at room temperature is used to control the temperature to 15-25°C.

8. The preparation method according to claim 6, characterized in that: The sulfur dioxide in step (2) is sulfur dioxide gas. Before the sulfur dioxide gas is introduced, the container containing the first mixed solution is evacuated to control the vacuum degree to be below 0.1 atm.

9. The preparation method according to claim 8, characterized in that: The sulfur dioxide gas is dehydrated by concentrated sulfuric acid.

10. The preparation method according to claim 6, characterized in that: The sealing time in step (3) is 20-28 hours.

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