A method for capturing reaction intermediates FSO2NH2

Abstract

This invention discloses a method for capturing the reaction intermediate FSO2NH2. The method involves selecting a suitable molecular sieve and adding it to the reaction solution for the synthesis of difluorosulfonyl imide from ammonia-sulfonyl fluoride (NH3-SO2F2). Utilizing the selective adsorption capacity of the molecular sieve, the reaction intermediate FSO2NH2 generated during the reaction is successfully captured. This method can also be used to adsorb and capture intermediates in extremely low concentrations and difficult to analyze in other series of chemical reactions. Furthermore, the materials used in this method are inexpensive and readily available, and the operation is simple and easy to implement. Identifying the captured intermediate components helps to understand the reaction pathway and mechanism. By further adjusting key processes, the formation of by-products can be significantly suppressed, thereby effectively improving the product yield.

Description

Technical Field

[0001] This invention belongs to the fields of chemical research and chemical engineering, and specifically relates to a method for capturing the reaction intermediate FSO2NH2. Background Technology

[0002] Serial reactions are among the most fundamental and complex chemical reactions. Analyzing the reaction pathways of serial reactions provides a direct understanding of the reactant transformation process, which is significant for improving production processes, reducing byproducts, and increasing yields. Serial reactions consist of multiple elementary reactions, some of which are rapid, with intermediates existing for extremely short periods and in very low quantities. When using methods such as online infrared spectroscopy, the resolution is limited and interference from various chemical substances makes it difficult to capture the characteristic peaks of the target intermediates. If a quencher is used to forcibly stop the reaction, the target intermediate cannot be directly characterized. The synthesis of bis(fluorosulfonyl)imide from NH3-SO2F2 is a typical serial reaction. Martin R. Johnson, in his method for synthesizing bis(fluorosulfonyl)imide and its related salts (patent CN104918913B), proposed that the initial reaction of NH3 with SO2F2 is a vigorous amino defluorination, yielding the reaction intermediate fluorosulfonamide (FSO2NH2). FSO2NH2 can then undergo a second amino defluorination to obtain sulfonamide, or be deprotonated through the fluorosulfonamide anion (FSO2NH2). - Further reaction of FSO2 with SO2F2 yields (FSO2)2NH. However, there is currently no direct evidence that FSO2NH2 exists as an intermediate, and this substance is highly reactive, easily hydrolyzed, and difficult to measure. Dong Jiajia also successfully synthesized the target product (FSO2)2NH using this reaction in a method for preparing an organic base salt of bis(fluorosulfonyl)imide (patent CN 110217764A), but some dimerization and hydrolysis byproducts still existed. Therefore, for this problem of reduced yield due to unclear reaction pathway, a simple and convenient method is urgently needed to capture intermediates to determine the reaction pathway.

[0003] Molecular sieves are commonly used as adsorbents in adsorption separation technology. Because zeolite molecular sieves have uniform pore sizes, molecules with a kinetic diameter smaller than the pore size can easily enter the crystal cavity and be adsorbed. Therefore, the selective adsorption of molecular sieve channels can be used to achieve the adsorption and capture of specific molecules. Summary of the Invention

[0004] The purpose of this invention is to provide a method for capturing the intermediate FSO2NH2 generated during the synthesis of bis(fluorosulfonyl)imide from NH3-SO2F2, thereby solving the technical problem of difficulty in separating or characterizing existing reaction intermediates due to their short reaction time, low content, and difficulty in separation. This method uses inexpensive and readily available materials, is simple to operate, and can be extended to other similar series-type liquid-phase reactions with fast reaction rates, complex processes, and numerous byproducts.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for capturing the reaction intermediate FSO2NH2 involves estimating the kinetic diameter of the intermediate FSO2NH2 based on the reactants (NH3 and SO2F2) and the product ((FSO2)2NH). Then, a molecular sieve with a corresponding pore size is selected based on this kinetic diameter, and after cleaning and activation, the sieve is added to the reaction solution for adsorption and collection during the reaction. After the reaction, the molecular sieve is removed, cleaned, and preliminarily dried. The intermediate structure is then determined through post-processing and characterization analysis. The specific operational steps are as follows:

[0007] 1) Select a molecular sieve with an appropriate pore size based on the kinetic diameter of the target molecule FSO2NH2;

[0008] 2) Clean the molecular sieve with water and solvent respectively to remove impurities, and activate it at 350℃~450℃ for 3~6 h;

[0009] 3) The cleaned and activated molecular sieve is wetted with solvent and then put into the reaction solution of NH3 and SO2F2 for adsorption;

[0010] 4) After the reaction is complete, remove the molecular sieve and wash it with solvent by shaking 5 to 10 times, 3 minutes each time, to remove the reaction liquid adhering to the surface of the molecular sieve (do not use sonication to prevent the loss of target molecules due to desorption).

[0011] 5) After removing the solvent from the obtained molecular sieve, a molecular sieve containing the target molecule FSO2NH2 can be obtained. It can be detected by infrared spectroscopy after grinding or by tandem liquid chromatography-mass spectrometry after solvent rinsing; or the target molecule can be collected by high temperature depressurization desorption and condensation method and then analyzed and characterized.

[0012] Furthermore, the molecular sieve is a 3A molecular sieve, a 4A molecular sieve, or a 5A molecular sieve.

[0013] Furthermore, the amount of the molecular sieve used is 5-10% of the total mass of the reaction solution.

[0014] Furthermore, the temperature of the reaction process is -20 to 80 ℃, and the pressure is 0.01 to 2 MPa.

[0015] Furthermore, aromatic hydrocarbons, halogenated hydrocarbons, ethers, esters, or nitriles are used as solvents in the reaction process.

[0016] The significant advantages of this invention are:

[0017] This invention provides a method for using molecular sieves to adsorb and capture the reaction intermediate FSO2NH2. In the synthesis of bis(fluorosulfonyl)imide from NH3-SO2F2, a molecular sieve is added to the reaction solution. Due to the strong selective adsorption capacity of the molecular sieve, the free intermediate FSO2NH2 generated during the reaction enters the sieve channels, thus obtaining a molecular sieve containing FSO2NH2. Its chemical structure is then determined through post-processing and characterization. By relying on the exclusion function of the molecular sieve, the influence of non-target substances in the analytical characterization is reduced. Furthermore, by qualitatively characterizing the intermediates captured by the molecular sieve, the causes of byproduct formation can be determined, thereby allowing for adjustments to the production process and improving product yield.

[0018] The method provided by this invention is very easy to operate, and the adsorbent material used is a commonly available molecular sieve, which is much cheaper than expensive online infrared and online nuclear magnetic resonance detection methods.

[0019] This method can also adsorb some highly reactive or decomposed intermediates, such as FSO2NH2, that are difficult to retain into the molecular sieve channels, thereby effectively solving some problems where the reaction pathway is uncertain and the cause of side reactions is unknown. Attached Figure Description

[0020] Figure 1 The image shows the FTIR spectrum of the molecular sieve powder after adsorption reaction intermediate FSO2NH2 in Example 1.

[0021] Figure 2 The image shows the FTIR spectrum of the molecular sieve powder after adsorption reaction intermediate FSO2NH2 in Example 2.

[0022] Figure 3 The image shows the FTIR spectrum of the molecular sieve powder after adsorption reaction intermediate FSO2NH2 in Example 3. Detailed Implementation

[0023] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0024] The synthesis of bis(fluorosulfonyl)imide from NH3-SO2F2 is used as an example to illustrate the specific process of using molecular sieves to adsorb and capture reaction intermediates, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in this invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0025] The synthesis of bis(fluorosulfonyl)imide from NH3-SO2F2 uses acetonitrile as the reaction solvent and triethylamine (NEt3) as the third reactant. The reaction of NH3 and SO2F2 to produce bis(fluorosulfonyl)imide occurs only in the liquid phase; therefore, the two gaseous reactants are added to a sealed reactor via bubbling. A gas mass flow meter (SevenStar Huachuang) is used to control the gas flow rate. Magnetic stirring is employed to enhance the mass transfer rate between the gas and liquid phases. To remove the heat released during the reaction and maintain the reaction temperature, the reactor is placed in a water bath.

[0026] Example 1

[0027] First, chemical modeling software was used to obtain the optimized structural dynamic diameter of the FSO2NH2 molecule, which is 3.402 mm. 4A molecular sieve (pore size 4) was selected. It is used for adsorption analysis.

[0028] 4A molecular sieves were soaked in acetonitrile, sonicated for 30 min, and the liquid was removed by filtration. The sieves were then soaked and washed with deionized water, sonicated for 30 min, and filtered again to remove the liquid. The washed 4A molecular sieves were placed in a crucible and activated in a muffle furnace at 450 °C for 6 h. After cooling to 150 °C, the sieves were transferred to a sealed bottle. 50 mL of acetonitrile and 30.3 g of NEt3 (0.3 mol, 3 eq) were added to a 250 mL three-necked flask. 7 g of the activated 4A molecular sieves were then added to the flask. After no more bubbles emerged, the flask was evacuated under an ice-water bath. 2.2 L of NH3 (0.1 mol) and 4.2 L of SO2F2 (0.2 mol) were introduced into the liquid through a venting tube at flow rates of 22 mL / min and 42 mL / min, respectively. The mixture was stirred to allow for reaction. The venting tube was sealed to prevent gas leakage and to allow observation of the remaining unreacted gas. Aeration was stopped after 100 min of reaction. At this point, the balloon had inflated to a volume of approximately 200 mL. After 2 h, the balloon completely collapsed, indicating that the gas had been completely consumed. The reaction was stopped, and the reaction liquid was filtered out. The 4A molecular sieve was washed 10 times with acetonitrile for 3 min each time, and the liquid was filtered out. Residual acetonitrile was removed under vacuum to obtain a dry molecular sieve. The molecular sieve was then ground in a mortar and pestle to obtain molecular sieve powder after adsorption under 0℃ reaction conditions. The infrared spectra of the activated molecular sieve powder and the molecular sieve powder after absorbing the reaction intermediate were measured respectively. The results are shown in [Figure 1]. Figure 1 .

[0029] Depend on Figure 1 As can be seen, the FTIR analysis of the molecular sieve powder sample after the absorption reaction intermediate showed two absorption peaks located at 1400 cm⁻¹. -1 and 1181 cm -1 Compared with the FTIR of FSO2NH2, the symmetric and asymmetric vibrational absorption peaks of S=O are slightly shifted under the adsorption environment of 4A molecular sieve, and the absorption signal is smaller. The product yield in this example is approximately 93%, which may be due to the reaction being carried out in an ice-water bath, resulting in a slower reaction rate and a higher intermediate content, but the smaller pore size of the molecular sieve leads to a reduced adsorption capacity. Nevertheless, it still demonstrates that molecular sieve adsorption can achieve the goal of capturing chemical reaction intermediates.

[0030] Example 2

[0031] Based on the optimized structural dynamics of the FSO2NH2 molecule, the diameter is 3.402. 5A molecular sieve (pore size 5) was selected. It is used for adsorption analysis.

[0032] The 5A molecular sieve was treated in the same way as described in Example 1, and then the infrared spectra of the activated molecular sieve powder and the molecular sieve powder after absorbing the reaction intermediate were measured respectively. The results are shown in [Figure 1]. Figure 2 .

[0033] Depend on Figure 2 As can be seen, the FTIR analysis of the molecular sieve powder sample after the absorption reaction intermediate showed two absorption peaks located at 1410 cm⁻¹. -1 and 1209 cm -1 Comparing the FTIR of FSO2NH2, the two absorption peaks are the symmetric and asymmetric vibrational absorption peaks of S=O, respectively, proving that the adsorption of the molecular sieve achieved the goal of capturing the chemical reaction intermediate. The product yield in this example is about 94%, which may be because the pore size of the 5A molecular sieve is more suitable for SO2NH2 molecules to enter, allowing for the adsorption of more molecules, thus resulting in a more obvious absorption peak.

[0034] Example 3

[0035] Take 7 g of the activated 5A molecular sieve from Example 2 and add it to a three-necked flask containing 50 mL of acetonitrile and 30.3 g of NEt3 (0.3 mol, 3 eq). After no more bubbles emerge, evacuate the flask under an ice-water bath to remove air, then place it in a 50 ℃ constant temperature water bath. Use a venting tube to introduce NH3 (2.2 L, 0.1 mol) and SO2F2 (4.2 L, 0.2 mol) into the liquid at flow rates of 22 mL / min and 42 mL / min, respectively. Start stirring to carry out the reaction. Seal the balloon to prevent gas leakage and observe the remaining unreacted gas. Stop venting after 100 min of reaction. At this time, the balloon inflates to a volume of about 500 mL. After 1 h, the balloon volume is about 100 mL. After 2 h, the balloon completely collapses, indicating that the gas has been completely consumed. After the reaction was stopped, the post-processing method of Example 1 was followed to obtain molecular sieve powder under reaction conditions of 50 °C. The infrared spectra of the activated molecular sieve powder and the adsorbed molecular sieve powder were measured respectively, and the results are shown in [Figure 1]. Figure 3 .

[0036] Depend on Figure 3 It can be seen that the absorbed molecular sieve powder sample at 1400 cm⁻¹ -1 and 1200 cm -1 The absorption signal at the point is very weak, indicating a low content of the reaction intermediate FSO2NH2. This corresponds to a fast reaction rate and severe side reactions under these conditions (50℃), resulting in a product yield reduced to 74%. Therefore, capturing and qualitatively characterizing the reaction intermediate can help adjust the production process and improve the product yield.

[0037] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for capturing the reaction intermediate FSO2NH2, characterized in that: In the liquid-phase reaction of NH3-SO2F2 to synthesize bis(fluorosulfonyl)imide, molecular sieves are used to collect the intermediate FSO2NH2 generated during the reaction, and the resulting molecular sieves adsorbed with the intermediate FSO2NH2 are then post-treated; the specific operation steps are as follows: 1) Based on the kinetic diameter of the target molecule FSO2NH2, 5A molecular sieve was selected; 2) Clean the molecular sieve with water and solvent respectively to remove impurities, and activate it at 350℃~450℃ for 3~6h; 3) The cleaned and activated molecular sieve is wetted with solvent and then put into the reaction solution of NH3 and SO2F2 for adsorption; 4) After the reaction is complete, remove the molecular sieve and wash it with solvent by shaking 5 to 10 times, 3 minutes each time, to remove the reaction liquid adhering to the surface of the molecular sieve. 5) After removing the solvent from the obtained molecular sieve, a molecular sieve containing the target molecule FSO2NH2 is obtained. After grinding, it is detected by infrared spectroscopy, or after rinsing with solvent, it is detected by tandem liquid chromatography-mass spectrometry, or the target molecule is collected by high temperature depressurization desorption and condensation, and then analyzed and characterized.

2. The method for capturing the reaction intermediate FSO2NH2 according to claim 1, characterized in that: The amount of molecular sieve used is 5-10% of the total mass of the reaction solution.

3. The method for capturing the reaction intermediate FSO2NH2 according to claim 1, characterized in that: The reaction temperature of the liquid phase reaction is -20 to 80 ℃, and the pressure is 0.01 to 2 MPa.

4. The method for capturing reaction intermediate FSO2NH2 according to claim 1, characterized in that: The liquid-phase reaction uses aromatic hydrocarbons, halogenated hydrocarbons, ethers, esters, or nitriles as solvents.

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