Preparation method, stabilization method and application of INO3 solution

Abstract

The invention discloses preparation and stabilization methods of an INO3 solution and application of the INO3 solution. The preparation method comprises the following steps: dissolving silver nitrate in a first organic solvent to form a silver nitrate solution; dissolving an iodine elementary substance in a second organic solvent to form an iodine elementary substance solution; mixing the silver nitrate solution with an iodine simple substance solution, and carrying out a reaction according to a reaction equation AgNO3 + I2-AgI + INO3; and separating AgI precipitate generated by the reaction to obtain an INO3 solution. When a non-acetonitrile solvent is used, acetonitrile needs to be added as a stabilizer, so that the volume content of acetonitrile in the final solution is greater than or equal to 50%. The INO3 solution can be used as a bifunctional reagent for synchronous iodination and nitration reactions of aromatic compounds. The half-life period of the INO3 solution prepared by the method provided by the invention in an acetonitrile system under the dark condition of 25 DEG C reaches 48.5 days, the product stability is good, the INO3 solution has excellent activity on the bifunctionalization reaction of aromatic compounds such as phenol, and nitrophenol and iodo-phenol products can be generated at the same time.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic chemical synthesis, and more particularly to a preparation method and stabilization method of INO3 solution and application thereof. BACKGROUND

[0002] Iodine nitrate (INO3) is a highly reactive monovalent iodine compound. The iodine (I + ) and nitro group (NO3 - ) in the molecule can be used as iodination reagent and nitration reagent respectively to realize one-step double functionalization reaction. However, the synthesis and storage of iodine nitrate (INO3) face great challenges: it hydrolyzes to form HNO3 and hypoiodous acid (HIO) when it comes into contact with water, and the latter quickly disproportionates into iodine (I2) and iodate (IO3 - ). The traditional preparation method uses I(NO3)3 to react with iodine at zero degrees below zero, but the preparation process of I(NO3)3 is complex and unstable, so it is extremely difficult to prepare INO3 at present.

[0003] Current research on iodine chemistry mainly focuses on negative one-valent (I - ) and positive five-valent (IO3 - ) compounds, and there is little research on positive one-valent iodine (I + ). For example, the AgNO3 / I2 aqueous disproportionation reaction disclosed in the Chinese granted invention patent (CN117169319B) can only generate IO3 - . Since the generated positive one-valent iodine is easily combined with OH - in the aqueous solution to form HIO, HIO is unstable and easily disproportionates into I - and IO3 - , so it is impossible to prepare INO3.

[0004] Therefore, it is urgent to propose a new method for efficiently and stably preparing iodine nitrate (INO3) to solve the problem of difficulty in synthesizing and storing positive one-valent iodine compounds in the prior art and promote its application in the fields of organic synthesis, energy materials, etc. SUMMARY

[0005] Therefore, it is urgent to propose a new method for efficiently and stably preparing iodine nitrate (INO3) to solve the problem of difficulty in synthesizing and storing positive one-valent iodine compounds in the prior art and promote its application in the fields of organic synthesis, energy materials, etc.

[0006] To solve the above technical problems, the present application provides a preparation method of INO3 solution, which comprises the following steps: dissolving silver nitrate in a first organic solvent to form a silver nitrate solution; dissolving iodine element in a second organic solvent to form an iodine element solution; mixing and reacting the silver nitrate solution with the iodine element solution, and separating the AgI precipitate generated in the reaction to obtain an INO3 solution.

[0007] Further, the first organic solvent is acetonitrile, and the second organic solvent is at least one selected from acetonitrile, carbon tetrachloride, chloroform, dichloromethane, ethyl acetate, pyridine, DMF, acetone, tetrahydrofuran, ethanol, isopropanol, propanol and butanol.

[0008] Further, the molar ratio of silver nitrate to iodine element is 1-10:1, the concentration of the silver nitrate solution is 0.001-1.25 mol / L, and the concentration of the iodine element solution is 0.001-1 mol / L.

[0009] Further, the reaction is carried out at 0-50°C, and the reaction time is 3-120 minutes.

[0010] Further, after the silver nitrate is dissolved in the first organic solvent to form a silver nitrate solution, the water content of the system is less than 1wt%.

[0011] The second aspect of the present application proposes a method for stabilizing the INO3 solution. When the second organic solvent is a non-acetonitrile solvent, a cyano-containing solvent is added to the separated INO3 solution as a stabilizer, and the solution is stored in the dark. The volume content of the stabilizer in the final solution is ≥50%.

[0012] Further, the stabilizer is selected from acetonitrile, propionitrile or butyronitrile.

[0013] Further, the stabilizer is acetonitrile, and the addition amount of the stabilizer is such that the volume ratio of acetonitrile in the final solution is 85-95%.

[0014] The third aspect of the present application proposes the application of the INO3 solution. The INO3 solution prepared by any of the above methods or any of the stabilized INO3 solutions is used as a bifunctional reagent for synchronous iodination and nitration of organic compounds.

[0015] Further, the organic compound is an aromatic compound, including phenol, tyrosine, aniline or anisole.

[0016] Compared with the prior art, the present application has the following beneficial effects: The application provides a preparation and stabilization method of INO3 solution and application thereof, and realizes directional reaction of silver nitrate and iodine element to prepare INO3 by adopting a non-water organic solvent system, acetonitrile is selected as a first solvent and a plurality of aprotic solvents are selected as second solvents, wherein the acetonitrile can effectively stabilize iodine positive ions and inhibit hydrolysis side reactions due to strong solubility, low water content and cyano coordination. When the second solvent is not acetonitrile, a cyano-containing solvent is added as a stabilizer for solution stabilization treatment, and the coordination between the cyano group and the iodine positive ion can significantly improve the stability of the product. Verification shows that the method can realize efficient synthesis of INO3, the half-life of INO3 in the acetonitrile system under normal temperature and light-proof conditions can reach 48.5 days, and the method has excellent reaction activity for simultaneous iodination and nitration of aromatic compounds such as phenol, mass spectrum analysis proves that nitrophenol and iodophenol products can be generated at the same time, and efficient bifunctional conversion is realized. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the scheme in the present application or prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0018] Figure 1 UV-Vis absorption spectrum of the INO3 acetonitrile solution of Example 1; Figure 2 Electrospray-Orbitrap high-resolution mass spectrum (negative ion mode) of the INO3 solution of Example 2; Figure 3 Electrospray-Orbitrap high-resolution mass spectrum (negative ion mode) of the INO3 solution of Example 3; Figure 4 UV-Vis absorption spectrum of the INO3 solution in Example 4; Figure 5A Total ion current chromatogram of the phenol control solution in Example 5; Figure 5B Total ion current chromatogram of the phenol-INO3 reaction product in Example 5; Figure 5C Mass spectrum (peak 1) of phenol in Example 5; Figure 5D Mass spectrum (peak 2) of nitrophenol in Example 5; Figure 5E Mass spectrum (peak 3) of o-iodophenol in Example 5; Figure 5F Mass spectrum (peak 4) of p-iodophenol in Example 5; Figure 6The INO3 absorbance and iodine element dosage relationship graph in Comparative Example 1; Figure 7 The INO3 generation amount and reaction time relationship graph in Comparative Example 2; Figure 8 The reaction temperature effect on INO3 generation amount graph in Comparative Example 3; Figure 9 The INO3 stability comparison graph in different solvent systems in Comparative Example 4; Figure 10 The acetonitrile content effect on INO3 solution stability graph in Comparative Example 5. DETAILED DESCRIPTION

[0019] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0020] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below.

[0021] Reaction principle description In the embodiments of the present application, the reaction chemical equation of silver nitrate (AgNO3) and iodine element in the organic solvent system is: AgNO3+I2→AgI↓+INO3. When silver nitrate is added to the iodine element solution, or iodine element is added to the silver nitrate solution, the two will rapidly react to generate insoluble AgI (silver iodide) and INO3. The reaction product is obviously different from the reaction product of silver nitrate in aqueous solution and iodine element. In the organic phase, due to the lack of OH - , I + hydrolysis to generate HIO and further disproportionation to I2 and IO3 - , so as to stably obtain INO3.

[0022] Example 1 The present embodiment provides a preparation and preservation method of INO3 solution, which comprises the following steps: S1, preparation of silver nitrate solution: 2.125 g of silver nitrate (12.5 mmol) is weighed and placed in a 50 mL polyethylene plastic tube, 50 mL of chromatographically pure acetonitrile (purity≥99.9%, water content≤0.1%) is added, and after being fully dissolved, it is mixed uniformly to prepare a 0.25 mol / L silver nitrate acetonitrile solution. The water content of silver nitrate and acetonitrile needs to be verified by a water titrator to ensure that the total water content of the system is <1 wt%. S2, Preparation of iodine solution: 1.588 g of iodine (6.25 mmol) was weighed into another 50 mL polyethylene plastic tube, 50 mL of chromatographically pure acetonitrile was added, and after dissolution, the mixture was uniformly mixed to prepare a 0.125 mol / L I2 acetonitrile solution; S3, Reaction process: 0.5 mL of silver nitrate acetonitrile solution (containing 0.125 mmol of AgNO3) was taken in a 15 mL polyethylene plastic tube, vortexed and shaken at 25°C, and I2 acetonitrile solution was added dropwise. The amount of I2 acetonitrile solution added was controlled to be 1.00 mL (0.125 mmol), and the molar ratio of AgNO3 to I2 was 1:1. After the addition was completed, the reaction was shaken for 10 min; S4, Separation and purification: the reaction solution of S3 was centrifuged at 5000 r / min for 5 min, and the supernatant and the precipitate were separated. The supernatant was the INO3 acetonitrile solution, and the bottom precipitate was silver iodide solid; S5, Determination of purity of byproduct: the precipitate was washed with ethanol for 3 times, and high-purity silver iodide was obtained after drying. 50 mg of silver iodide was dissolved with nitric acid, and an excess of sodium sulfide solution was added to generate silver sulfide precipitate. After washing with ultrapure water and drying, the weight was 26.2 mg, and the purity of silver iodide was calculated to be 99.2%; S6, Product characterization: 0.3 mL of the supernatant after centrifugation (INO3 acetonitrile solution) was diluted to 3.3 mL with fresh acetonitrile, and the INO3 solution was characterized by ultraviolet-visible absorption spectrum (200-700 nm), as shown in Figure 1 It can be seen that, compared with the silver nitrate solution, the INO3 solution generated after the addition of I2 has a characteristic absorption peak, and the characteristic absorption is 460 nm. Figure 1

[0023] S7, Preservation: the INO3 solution was transferred to a light-proof container, sealed and stored at room temperature.

[0024] In this embodiment, acetonitrile is selected as the organic solvent. On the one hand, silver nitrate has good solubility in acetonitrile, and acetonitrile can effectively dissolve silver nitrate, so that silver nitrate can be prepared into a solution to facilitate subsequent reactions. On the other hand, acetonitrile is used instead of water to dissolve silver nitrate to avoid the generation of iodate ions.

[0025] Example 2 The embodiment provides a preparation and preservation method of INO3 solution, which uses tetrahydrofuran to prepare INO3, and specifically includes the following steps: ​S1, Preparation of silver nitrate solution: 34 g of silver nitrate (0.2 mol) was weighed into a 1000 mL glass container, 1000 mL of analytical pure acetonitrile was added, and after being dissolved, it was mixed uniformly to prepare a 0.2 mol / L silver nitrate acetonitrile solution, and the total water content in the silver nitrate and acetonitrile system was less than 1 wt%; S2, Preparation of iodine solution: 25.4 g of iodine (0.1 mol) was weighed into another 1000 mL glass container, 1000 mL of analytical pure tetrahydrofuran was added, and after ultrasonic dissolution, it was vortex mixed uniformly to prepare a 0.1 mol / L I2 tetrahydrofuran solution. In this step, at least one of the other organic solvents carbon tetrachloride, chloroform, dichloromethane, ethyl acetate, pyridine, DMF, acetone, ethanol, isopropanol, propanol, and butanol can be used instead of tetrahydrofuran; S3, Reaction process: 200 mL of I2 tetrahydrofuran solution (containing 0.02 mol of I2) was taken in a 500 mL conical flask, and 200 mL of silver nitrate acetonitrile solution (containing 0.04 mol of AgNO3) was slowly added dropwise at 20°C with gentle shaking by hand, and the molar ratio of AgNO3:I2 was 2:1; S4, Separation and purification: After the reaction solution was placed for 1 h, it was filtered through an organic reagent-resistant filter membrane to obtain a clear red INO3 tetrahydrofuran solution, and the solid obtained by filtration was silver iodide; S5, By-product treatment: The silver iodide precipitate was washed with ethanol to obtain a high-purity AgI by-product; S6, Product characterization: The INO3 solution was characterized and detected by electrospray-Orbitrap high-resolution mass spectrometry, and the results are shown in Figure 2 As shown in the figure, the negative ion [I(NO3)2] of the INO3 adduct nitrate was clearly detected on the mass spectrum. - The results show that the main product in the reaction solution of iodine and silver nitrate is INO3.

[0026] S7, Stabilization treatment: Acetonitrile was added to the INO3 solution to adjust the volume content of acetonitrile to 85% to prepare a stable INO3 solution; S8, Preservation: The stabilized INO3 solution was transferred to a light-proof container, sealed, and stored at room temperature.

[0027] Example 3 The present embodiment provides a method for preparing and storing INO3, which adopts an ethanol preparation method for preparing INO3, and specifically includes the following steps: S1, Preparation of silver nitrate acetonitrile solution: 42.5 g of silver nitrate (0.25 mol) was weighed into a 200 mL brown glass bottle, 200 mL of analytical pure acetonitrile was added, and after being dissolved, it was mixed uniformly to prepare a 1.25 mol / L silver nitrate acetonitrile solution, and the total water content in the silver nitrate and acetonitrile system was less than 1 wt%. S2. Preparation of iodine ethanol solution: Weigh 50.8 g of iodine (0.2 mol) into another 200 mL brown glass bottle, add 200 mL of anhydrous ethanol, dissolve by sonication, and store in the dark to obtain a 1.0 mol / L I2 ethanol solution. S3. Reaction process: Take 16 mL of silver nitrate acetonitrile solution (containing 20 mmol AgNO3) into a 100 mL Erlenmeyer flask, gently shake by hand at 20 °C, and slowly add 4 mL of I2 ethanol solution (containing 4 mmol I2). The molar ratio of AgNO3 to I2 is 5:1. React for 15 min. S4. Separation and purification: The reaction solution is filtered through a 0.22μm PTFE filter membrane, and the filtrate is a reddish-brown ethanol solution of INO3; S5. Byproduct treatment: Wash the silver iodide precipitate with ethanol to obtain high-purity AgI byproduct; S6. Product Characterization: The INO3 ethanol solution was characterized and detected using electrospray ionization-Orbitrap high-resolution mass spectrometry. The results are as follows: Figure 3 As shown, the anion [I(NO3)2], which is composed of INO3 and nitrate, was clearly detected in the mass spectrometer. - This indicates that INO3 was generated in the solution from the reaction of elemental iodine with silver nitrate.

[0028] S7. Stabilization treatment: Add acetonitrile to the INO3 solution and adjust the volume content of acetonitrile to 90% to obtain a stable INO3 acetonitrile solution; S8. Storage: Transfer the stabilized INO3 solution to a light-proof container, seal it, and store it at room temperature.

[0029] Example 4 This embodiment provides a method for preparing low-concentration INO3, specifically including the following steps: S1. Preparation of dilute silver nitrate solution: Weigh 8.5 mg of silver nitrate (1 × 10⁻⁶) -3 50 mL of chromatographic grade acetonitrile was added to a 50 mL volumetric flask to prepare 1 × 10⁻⁶ mmol) -3 mol / L silver nitrate solution, the total water content of the silver nitrate and acetonitrile system is <1wt%; S2. Preparation of iodine solution: Weigh 12.7 mg of elemental iodine (5 × 10⁻⁶ mg / L) -2 In another 50 mL volumetric flask, 50 mL of chromatographically pure acetonitrile was added to prepare 1 × 10 mmol) -3 mol / L I2 solution; S3. Reaction process: Take 50 mL of silver nitrate solution (containing 5 × 10⁻⁶ ppm) -2 mmol AgNO3) and 5.0 mL iodine solution (containing 5 × 10 mmol AgNO3) -3Mix AgNO3 (mmol I2) with a molar ratio of AgNO3:I2 of 10:1 and react at 25℃ for 30 min. S4. Byproduct treatment: Wash the precipitate three times with ethanol and dry it to obtain high-purity silver iodide.

[0030] S5. Enhanced Detection: The INO3 acetonitrile solution obtained in S3 was subjected to ultraviolet scanning at 200-700 nm using a 10cm optical path quartz cuvette. Figure 4 As shown in the spectrum, the characteristic ultraviolet absorption peak of INO3 can be seen.

[0031] S6. Storage: Transfer the INO3 acetonitrile solution to a light-protected container, seal it, and store it at room temperature.

[0032] Example 5 This embodiment provides a reaction method for achieving efficient bifunctionalization (simultaneous iodination and nitration) of phenol using INO3 solution, specifically including the following steps: Preparation of S1 and INO3 solutions: Nitric acid INO3 acetonitrile solution was prepared according to the method described in Example 1; S2. Preparation of phenol solution: Accurately weigh 94.1 mg of phenol, dissolve it in 10 mL of acetonitrile, and prepare a 0.01 mol / L phenol solution; S3. Reaction process: Take 2 mL of phenol solution into a reaction tube, add 100 μL of INO3 solution, and vortex at room temperature for 5 minutes. S4. Sample pretreatment: Take 10 μL of reaction solution, dilute it with 990 μL of methanol to a final volume of 1 mL, mix thoroughly and then test. S5. Analysis and testing conditions: The analysis was performed using a liquid chromatography-Orbitrap high-resolution mass spectrometry system. The instrument parameters are set as shown in Table 1 below.

[0033] Table 1: Parameters for Analytical Conditions of Liquid Chromatography-Mass Spectrometry S6. Results Analysis: Test results are as follows... Figures 5A-5F As shown, nitrophenol (m / z 138.019) and iodophenol (m / z 218.953) products were detected.

[0034] Figure 5A The display showed that only the characteristic signal peak of phenol (peak 1) was detected when no INO3 solution was added. Figure 5C (as shown), and Figure 5B The results showed that after adding INO3 solution, in addition to retaining the characteristic peak of phenol (peak 1), three new characteristic peaks were added: peak 2 (characteristic peak of nitrophenol), Figure 5D Peak 3 (characteristic peak of o-iodophenol) Figure 5E Peak 4 (characteristic peak of p-iodophenol) and peak 5 (characteristic peak of p-iodophenol)Figure 5F ), the reaction of INO3 solution with phenol shows that INO3 has high activity and can rapidly react with phenol to generate nitrophenol and iodophenol, realizing efficient difunctionalization conversion. This reaction characteristic not only significantly improves the synthesis efficiency, reduces the waste emissions generated by multi-step reactions, and meets the concept of green chemical synthesis, but also experimentally verifies that aniline, anisole, tyrosine and other aromatic compounds also exhibit excellent difunctionalization reaction performance, and has wide substrate applicability.

[0035] Comparative Example 1 This comparative example investigates the influence of iodine elemental dosage on the generation of INO3, which specifically includes the following steps: Reference group: prepare INO3 solution according to the method of Example 1, and the addition amount of I2 acetonitrile in step S3 is 125 μmol; Variable group: adjust the addition amount of I2 acetonitrile solution to 31.25 μmol, 62.5 μmol, 93.75 μmol, and 175 μmol, respectively, and the remaining conditions are exactly the same as Example 1; Detection: take 0.3 mL of prepared INO3 solution in each group and add 3 mL of acetonitrile, and use a UV spectrophotometer to measure the absorbance A of INO3 solution at 460 nm at different times, and the results are shown in Figure 6 .

[0036] Figure 6 The analysis results show that under the condition of excess silver nitrate (fixed at 125 μmol), the absorbance (y) of the system at 460 nm and the addition amount (x) of iodine elemental substance (I2) present a significant linear correlation relationship, and the fitting equation is y = 0.034x - 0.924, and the correlation coefficient R 2 reaches 0.980.

[0037] Comparative Example 2 This comparative example investigates the influence of reaction time on the generation of INO3, which specifically includes the following steps: Reference group: prepare INO3 solution according to the method of Example 1, and the reaction time of step S3 is 10 min; Variable group: adjust the reaction time to 3 min, 6 min, 30 min, 60 min, and 120 min, respectively, and the remaining conditions are exactly the same as Example 1; Detection: take 0.3 mL of prepared INO3 solution in each group and add 3 mL of acetonitrile, and use a UV spectrophotometer to measure the absorbance A of INO3 solution at 460 nm at different times, and the results are shown in Figure 7 .

[0038] Figure 7The experimental results show that the reaction time has little effect on the amount of INO3 produced. This phenomenon indicates that the reaction rate of silver nitrate with elemental iodine (I2) is extremely fast, and the reaction is basically completed after the feeding is stopped. Therefore, the amount of product produced does not change significantly with the extension of reaction time.

[0039] Comparative Example 3 This comparative study investigated the effect of reaction temperature on INO3 formation, specifically including the following steps: Reference group: INO3 solution was prepared according to the method of Example 1, and the reaction temperature in step S3 was 25°C; Variable group: The reaction temperature was adjusted to 0℃ and 50℃ respectively, and the other conditions were exactly the same as in Example 1; Detection: For each group, 0.3 mL of the prepared INO3 solution was added to 3 mL of acetonitrile, and the absorbance A at 460 nm was measured using a UV spectrophotometer. The relative content of INO3 was calculated based on the absorbance. The results are as follows: Figure 8 As shown.

[0040] Depend on Figure 8 It can be seen that the reaction temperature (0~50℃) has little effect on the product yield. Specifically, the yield of INO3 is slightly lower at 0℃, while the yields at 25℃ and 50℃ are basically the same, an increase of about 10% compared to 0℃. This phenomenon fully demonstrates that the reaction conditions of silver nitrate and I2 are mild and the reaction rate is fast, and it can be carried out efficiently in the temperature range of 0~50℃ under normal pressure.

[0041] Comparative Example 4 This comparative study investigated the effect of different organic solvents on the stability of INO3, specifically including the following steps: Reference group: INO3 solution (acetonitrile system) prepared according to the method of Example 1; Variable group: In step S2, dichloromethane, tetrahydrofuran, ethanol, and DMF were used to replace acetonitrile to prepare the I2 solution, and the other conditions were exactly the same as in Example 1; Detection: Each group of reaction solutions was stored in a constant temperature environment of 25℃ in the dark; 0.3 mL of sample was taken periodically and diluted with 3 mL of the corresponding solvent; the absorbance A at 460 nm was measured by ultraviolet spectrophotometer; the time-lnA curve was plotted and the half-life was calculated.

[0042] The experimental results are shown in Table 2 and Figure 9As shown, there is a significant difference in the stability of INO3 in different solvent systems. Specifically, the acetonitrile system has the best stability, with a half-life of INO3 of 48.5 days; the dichloromethane system is second, with a half-life of 24.4 days (about half of the acetonitrile system); and in solvents such as ethanol, tetrahydrofuran and DMF, the stability is poor, with half-lives of only 0.19 days, 0.39 days and 0.22 days, respectively. This significant difference in stability confirms that acetonitrile is the ideal stabilizer for INO3, and the stabilizing effect is mainly due to the cyan group (-C≡N) in the acetonitrile molecule, which can effectively stabilize the positive monovalent iodine (I + ). Based on this, the preparation of INO3 can be directly carried out in the acetonitrile solvent system (dissolving I2 in acetonitrile for reaction), or the product can be prepared in other solvents first and then the stability of the product can be improved by adding acetonitrile as a stabilizer.

[0043] Table 2: Comparison of the stability of INO3 in different organic solvents Comparative Example 5 This comparative example investigates the effect of adding acetonitrile to the INO3 solution on its stability. Specifically, 2 mL of the unstabilized INO3 solution prepared in step S4 of Example 3 is taken, and different volumes of acetonitrile are added to make the volume content of acetonitrile 50%, 70%, 80%, 90%, and 95%. The solutions are stored in the dark at 25°C, and the absorbance A at 460 nm is measured for each sample, the time-lnA curve is plotted, and the half-life is calculated, as shown in Table 3 and Figure 10 .

[0044] Table 3: Effect of acetonitrile content on the stability of INO3 solution The test results show that acetonitrile has a significant stabilizing effect on INO3. In the INO3 solution prepared in the ethanol system, as the proportion of acetonitrile increases (50% to 95%), the half-life of INO3 shows a clear gradient increase: from the initial 0.28 days (50% acetonitrile) to 2.21 days (95% acetonitrile). It is particularly noteworthy that when the acetonitrile content reaches 95%, the half-life is 7.9 times that of the 50% acetonitrile system, fully confirming the strong correlation between acetonitrile concentration and stability effect.

[0045] Comparative Example 6 The comparative example further verifies the effect of adding different stabilizers in INO3 solution on its stability. The specific method is as follows: 2 mL of the unstabilized INO3 solution prepared in step S4 of Example 2 is taken, and an equal volume (85% of the final volume) of methanol, butyronitrile, acetonitrile (control), acetone, and DMF is added, respectively. After mixing uniformly, the mixture is stored at 25°C in the dark. The absorbance at 460 nm is measured, the time-lnA curve is plotted, and the half-life is calculated. The results are shown in Table 4 below.

[0046] Table 4: Effect of different stabilizers on the stability of INO3 solution From the test results, it can be seen that the stabilizing effect of acetonitrile on INO3 is mainly due to the fact that the cyano group (-C≡N) in the molecule contains a lone pair of electrons, which can form a coordination bond with the positive monovalent iodine (I + ), thereby effectively stabilizing the structure of INO3. The experimental results show that the stability of the cyano-containing solvents (acetonitrile, butyronitrile) is significantly higher than that of the non-cyano solvents (methanol, acetone, DMF), among which acetonitrile has the best stabilizing effect. With the increase of the alkyl chain, the steric hindrance of butyronitrile increases, which gradually weakens the coordination ability of the cyano group with I + , and the stability decreases accordingly. In addition, although methanol, acetone, and DMF have polarity and nitrogen-containing properties, respectively, they cannot effectively stabilize INO3 due to the lack of cyano structure. The stabilizing effect of cyano-containing solvents is better than that of non-cyano solvents. At the same time, acetonitrile itself is difficult to be oxidized and can resist the oxidation of INO3, thereby providing a stable solvent environment for INO3. Therefore, through the coordination of the lone pair of electrons of the cyano group and the anti-oxidation property of acetonitrile itself, the long-term stability of INO3 in solution is ensured.

[0047] Verification example: stability verification of INO3 solution This verification example system verifies the stability differences of the INO3 solutions prepared in Examples 1-4 under different conditions, including the acetonitrile standard system (0.25 mol / L), the tetrahydrofuran system (0.1 mol / L, divided into unstabilized and 85% acetonitrile stabilized two groups), the ethanol system (divided into before stabilization and after 90% acetonitrile stabilization), and the ultra-low concentration system. All samples are stored at 4°C in the dark, 25°C in the dark, and 25°C without light, respectively. The half-life is calculated by periodically measuring the absorbance at 460 nm, and the degradation products are verified by mass spectrometry. Each group has 3 parallel samples. The ultra-low concentration system uses a 10 cm optical path cuvette and solid-phase extraction concentration to enhance the detection. The results are shown in Table 5 below.

[0048] Table 5: Stability data of INO3 in different solvent systems and storage conditions The experimental results show that the stability of acetonitrile system is the best, the half-life is 48.5 days under the condition of 25℃ and avoiding light, and the influence of temperature is small. In contrast, the stability of tetrahydrofuran and ethanol systems is poor without stabilization, especially under the condition of not avoiding light, the decomposition rate is significantly accelerated. By adding acetonitrile as a stabilizer (85% and 90%), the stability of these two systems is obviously improved, but still far from the pure acetonitrile system. The ultra-low concentration system has good stability under the condition of avoiding light, but it will still cause significant degradation without avoiding light. Therefore, the storage condition of avoiding light is beneficial to improve the stability of all systems, especially for tetrahydrofuran and ethanol systems and low concentration systems.

[0049] In summary, the best preservation scheme of INO3 solution is: first of all, acetonitrile solvent is preferred, and strict light-avoiding storage conditions are required, and the temperature can be controlled at conventional room temperature; if other solvent systems must be used, a large amount of acetonitrile must be added as a stabilizer and strict light-avoiding measures must be implemented.

[0050] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can be implemented in many different forms, and contrary to the above-described embodiments, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing specific embodiments, or make equivalent replacements to some technical features. Any equivalent structure made by using the content of the present application, directly or indirectly applied to other related technical fields, is also within the scope of the patent protection of the present application.

Claims

1. A method for preparing an INO3 solution, characterized by, The method comprises the following steps: dissolving silver nitrate in a first organic solvent to form a silver nitrate solution; dissolving elemental iodine in a second organic solvent to form an elemental iodine solution; mixing the silver nitrate solution and the elemental iodine solution to react, and separating the AgI precipitate generated in the reaction to obtain an INO3 solution.

2. The method of claim 1, wherein the INO3 solution is prepared by the steps of: The first organic solvent is acetonitrile, and the second organic solvent is at least one selected from acetonitrile, carbon tetrachloride, chloroform, dichloromethane, ethyl acetate, pyridine, DMF, acetone, tetrahydrofuran, ethanol, isopropanol, propanol and butanol.

3. The method of claim 1, wherein the INO3 solution is prepared by the steps of: The molar ratio of silver nitrate to elemental iodine is 1-10:1, the concentration of the silver nitrate solution is 0.001-1.25 mol / L, and the concentration of the elemental iodine solution is 0.001-1 mol / L.

4. The method of claim 1, wherein the INO3 solution is prepared by the steps of: The reaction is carried out at 0-50°C, and the reaction time is 3-120 minutes.

5. The method of claim 2, wherein the INO3 solution is prepared by the steps of: After the silver nitrate is dissolved in the first organic solvent to form the silver nitrate solution, the water content of the system is less than 1wt%.

6. A method of stabilizing an INO3 solution prepared according to claim 2, characterized by, When the second organic solvent is a non-acetonitrile solvent, a cyano-containing solvent is added to the separated INO3 solution as a stabilizer, and the solution is stored in the dark, the volume content of the stabilizer in the final solution is ≥50%.

7. The method of stabilizing an INO3 solution according to claim 6, wherein The stabilizer is selected from acetonitrile, propionitrile or butyronitrile.

8. The method of stabilizing an INO3 solution according to claim 7, wherein, The stabilizer is acetonitrile, and the addition amount of the stabilizer is to make the volume ratio of acetonitrile in the final solution reach 85-95%.

9. Use of an INO3 solution, characterized in that The INO3 solution prepared by any one of claims 1-5 or the stabilized INO3 solution of any one of claims 6-8 is used as a bifunctional reagent for synchronous iodination and nitration of an organic compound.

10. Use according to claim 9, characterized in that, The organic compound is an aromatic compound, including phenol, tyrosine, aniline or anisole.

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