Leaf aromatics, synthesis method and application thereof

Abstract

The present invention discloses a leaf aromatic hydrocarbon and its synthesis method and application, which belongs to the technical field of iodine pollution prevention and control. Leaf aromatic hydrocarbon has the following molecular structure: it can not only capture volatile I2 in the air, but also quickly and with high adsorption capacity adsorb I3 in water. ‑ ions and can be recycled, opening up a new way to purify iodine-contaminated water.

Description

Technical Field

[0001] The present invention relates to a leaf aromatic hydrocarbon, in particular to a leaf aromatic hydrocarbon with a propeller blade structure, a method for synthesizing the leaf aromatic hydrocarbon, and a method for synthesizing the leaf aromatic hydrocarbon by adsorbing I2 or I3. - The invention relates to an application in various aspects, and belongs to the technical field of iodine pollution prevention and control. Background Art

[0002] With the increase of energy demand and the intensification of carbon dioxide emissions, nuclear energy has attracted widespread attention as an alternative clean energy source in the past few decades. Radioactive iodine, including molecular iodine (I2) and a small amount of inorganic iodide (such as I - , I 2n+1 - and IO3 - ) is one of the main fission products produced during the nuclear fission of nuclear fuel. Due to the volatility of iodine, once a nuclear reactor accident occurs, radioactive iodine can easily escape into the environment and become the main source of radioactive pollution. For example, 129 I has a long half-life (1.57×10 7 ), will cause permanent pollution to the environment, and 131 Iodine is highly volatile and affects human metabolism. Therefore, effectively capturing radioactive iodine is crucial to the development of the nuclear industry and the protection of the ecological environment.

[0003] So far, research on iodine capture materials has mainly focused on solid-state materials including zeolites, metal-organic frameworks (MOFs), and covalent organic frameworks (COFs). However, the low iodine loading capacity and incomplete regeneration of zeolites, the relatively poor thermal and water stability of MOFs, and the harsh synthesis conditions and unclear chemical structure of COFs have significantly limited their further practical applications. Therefore, the development of promising and appropriate adsorbents to capture and store radioactive iodine in nuclear fuel is very important, but also a challenge.

[0004] Macrocyclic aromatic hydrocarbons composed of aromatic rings substituted by hydroxyl or alkoxy groups connected by methylene or methylene bridges, such as calix[n]arenes, pillar[n]arenes, biphenyl[n]arenes, prism[n]arenes, and pagoda[n]arenes, have received considerable attention in recent years due to their ease of synthesis and their great potential in the adsorption, separation, and storage of hydrocarbons. They are also good candidates for the adsorption of radioactive iodine. The literature (“Reversible Iodine Capture by Nonporous Pillar[6]arene Crystal”, K. Jie, et al., J. Am. Chem. Soc., 2017, 139, 15320.) discloses that fully ethylated pillar[6]arene successfully adsorbed iodine vapor, with an adsorption capacity of 20.1 wt%, and the charge transfer interaction between I2 and pillar[6]arene is the main driving force. The literature (“Terphen[n]arenes andQuaterphen[n]arenes(n=3-6):One-Pot Synthesis,Self-Assembly intoSupramolecular Gels,and Iodine Capture,B.Li,etal.,Angew.Chem.,Int.Ed.,2019,58,3885.) discloses the synthesis of triphenyl[n]arenes and tetraphenyl[n]arenes, and their self-assembly to form supramolecular organogels. Studies have found that these dry gel materials can effectively capture volatile iodine, not only in aqueous media but also in the gaseous state. Recently, the literature (“Phenyl-Extended Resorcin[4]arenes:Synthesis and HighlyEfficient Iodine Adsorption”,D.Li,et al. al, Angew. Chem., Int. Ed., 2024, 63, e202411261.) disclosed the synthesis of fully hydroxylated extended resorcinol [4] arene and found that it has a strong affinity for I3 in aqueous solution. — The ions showed excellent adsorption capacity, with an adsorption kinetic rate of 1.18×10 -2 g·mg -1 min -1 Although considerable efforts have been made to develop macrocyclic radioiodine adsorption materials, they still suffer from defects such as low adsorption capacity, slow adsorption rate, and single captured iodine species. Summary of the Invention

[0005] In view of the defects of the prior art, the first object of the present invention is to provide a leaf aromatic hydrocarbon, which is a macrocyclic aromatic hydrocarbon with a propeller blade structure and rich in nitrogen heteroatoms, which can not only capture volatile I2 in the air, but also quickly and efficiently adsorb I3 in aqueous solution. - ions, can be used as iodine adsorption materials.

[0006] The second object of the present invention is to provide a method for synthesizing leaf aromatics, which is simple and easy to implement, has mild conditions, low production cost, and can be produced on a large scale.

[0007] The third object of the present invention is to provide an application of leaf aromatics as I2 or I3 - The application of adsorption materials has the characteristics of fast adsorption rate, large capacity, and recyclability. It can be used as a stationary phase in column devices, opening up a new way to purify iodine-contaminated water.

[0008] In order to achieve the above technical objectives, the present invention provides a leaf aromatic hydrocarbon having the following molecular structure:

[0009]

[0010] Bladearene is a macrocyclic aromatic hydrocarbon. Its single crystal structure shows a propeller blade structure, so it is named Bladearene (B1). It is mainly composed of pyromellitic acid imide units and fully methylated resorcinol units. Its propeller blade structure not only has a stable conformation but also forms a smaller nanoscale cavity that can accommodate I2 molecules or I3 - ions, and the ring is rich in nitrogen heteroatoms. The lone pair electrons on the nitrogen heteroatoms can be transferred to the antibonding orbital (s*) of I2 to form a strong charge transfer complex, thereby - It exhibits high adsorption activity, which can not only capture volatile I2 in the air, but also quickly and highly capture I3 in water. - ion.

[0011] The present invention also provides a method for synthesizing leaf aromatics, which comprises the following steps:

[0012] 1) 2,4-dimethoxybenzylamine and 1,2,4,5-benzenetetracarboxylic anhydride undergo imidization reaction to obtain an intermediate;

[0013] 2) The intermediate undergoes condensation reaction with paraformaldehyde to obtain;

[0014] The intermediate has the following molecular structure:

[0015]

[0016] As a preferred embodiment, the molar ratio of the 2,4-dimethoxybenzylamine to the 1,2,4,5-benzenetetracarboxylic anhydride is 2 to 2.5:1. The theoretical molar ratio of 2,4-dimethoxybenzylamine to 1,2,4,5-benzenetetracarboxylic anhydride is 2:1. An appropriate excess of 2,4-dimethoxybenzylamine can ensure that the two anhydride groups of the 1,2,4,5-benzenetetracarboxylic anhydride are fully imidized.

[0017] As a preferred embodiment, the imidization reaction conditions are: a temperature of 100-120°C and a reaction time of 8-16 hours. Under these preferred reaction conditions, both anhydride groups of 1,2,4,5-benzenetetracarboxylic anhydride are fully imidized. If the reaction temperature is too low or the reaction time is too short, the primary intermediate product is an amide. More preferred reaction temperatures are 110-120°C and reaction times are 10-14 hours.

[0018] As a preferred embodiment, the molar ratio of the intermediate to paraformaldehyde is 1:3-5, wherein the paraformaldehyde is measured based on the formaldehyde units it contains. Controlling the paraformaldehyde ratio within an appropriate range not only ensures sufficient conversion of the intermediate but also allows for the production of a trimer structure based on the intermediate as a unit, thereby reducing the formation of other polymeric byproducts.

[0019] As a preferred embodiment, the condensation reaction conditions are: using boron trifluoride etherate as a catalyst, the temperature is room temperature, and the reaction time is 10 to 20 minutes. By using boron trifluoride etherate as a catalyst during the condensation reaction, the reaction can be carried out under milder reaction conditions, significantly reducing the reaction temperature, shortening the reaction time, and improving the conversion rate.

[0020] The present invention also provides an application of leaf aromatics as I2 or I3 - Adsorption material application.

[0021] As a preferred solution, the leaf aromatics are used to adsorb I2 vapor in the air, or to adsorb I3 in the aqueous solution. - .

[0022] Compared with the existing technology, the technical solution of the present invention brings the following beneficial technical effects:

[0023] The leaf aromatics of the present invention have a propeller blade structure and are rich in nitrogen heteroatoms. They can not only capture volatile I2 in the air, but also quickly and efficiently adsorb I3 in aqueous solution. - ions, and use them as iodine adsorbents to absorb I2 in the air or I3 in aqueous solution. - The ions exhibit characteristics such as fast adsorption rate, large capacity, and recyclability, and can be used as a stationary phase in column devices, opening up a new way to purify iodine-contaminated water.

[0024] The synthesis method of leaf aromatics of the present invention is simple and easy, has mild conditions, low production cost and can realize large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 (a) is the single crystal structure of B1, and (b) is the unit cell structure of B1.

[0026] Figure 2 (a) shows the color change of B1 after adsorption of iodine vapor; (b) shows the absorption effect of B1 on iodine vapor over time; (c) shows the full-spectrum XPS spectrum of B1 before and after iodine vapor adsorption; (d) shows the I 3d XPS spectrum of B1 after iodine vapor adsorption.

[0027] Figure 3 (a) is UV-visible absorption spectrum; (b) is the absorption spectrum of I3 at different times. - / H2O solution (0.25mM) after adding B1; (c) is the adsorption efficiency of B1 in adsorbing I3 - / H2O solution (0.25mM) before and after full spectrum XPS spectrum; (d) B1 adsorbed I3 - I 3d XPS spectrum after addition of 1% H2O solution (0.25 mM).

[0028] Figure 4 is a histogram of adsorption efficiency and cycle number.

[0029] Figure 5 This is a photo of the glass column adsorption device.

[0030] Figure 6 For adsorption of mobile I3 using B1 as stationary phase - / UV-vis absorption spectra before and after H2O solution; Note: due to 1.0mM I3 - The high UV absorption of the HCl / H2O solution exceeded the instrument detection limit, so it was diluted 4-fold to 0.25 mM for spectroscopic measurements.

[0031] Figure 7 Compound B1 1 H NMR spectrum.

[0032] Figure 8 Compound B1 1 C NMR spectrum. DETAILED DESCRIPTION

[0033] The following specific examples are intended to further illustrate the present invention, rather than to limit the scope of protection of the claims.

[0034] Unless otherwise specified, the chemical raw materials involved in the following specific examples are conventional commercially available raw materials.

[0035] Example 1

[0036] Synthesis of leaf aromatics:

[0037] 1) 2,4-Dimethoxybenzylamine (1.09 g, 5 mmol) and 1,2,4,5-benzenetetracarboxylic anhydride (2.01 g, 12 mmol) were reacted in 35 mL of N,N-dimethylformamide at 110°C for 12 h. After cooling to room temperature, the reaction mixture was poured into water. The yellow precipitate was washed with water and then dried under vacuum to obtain intermediate 2 with a yield of 51%.

[0038] Intermediate 2 (1.03 g, 2.0 mmol) and paraformaldehyde (180 mg, 6.0 mmol) were added to 150 mL of dichloromethane. Boron trifluoride diethyl etherate (0.3 mL, 2.4 mmol) was added as a catalyst. The reaction was stirred at room temperature for 15 minutes. 50 mL of water was added to quench the reaction. The organic layer was separated and dried over anhydrous MgSO₄. The solvent was removed in vacuo, and the mixture was separated by silica gel column chromatography using a dichloromethane:ethyl acetate ratio of 20:1 by volume as the eluent to afford the aromatic compound (B1) in a moderate yield (25%).

[0039] The structure of leaf arene B1 was fully characterized by 1H NMR and 13C NMR spectroscopy.

[0040] The specific reaction formula is as follows:

[0041]

[0042] Example 2

[0043] Synthesis of B1 single crystal:

[0044] The leaf aromatic hydrocarbon (3 mg) was dissolved in a dichloromethane / tetrahydrofuran (V / V=1:1) mixed solvent (2 mL) to form a homogeneous solution. The solution was slowly evaporated at room temperature to obtain a light yellow single crystal.

[0045] X-ray analysis of B1 crystals showed that it was of space group P-1 and triclinic system. Figure 1 As shown in Figure a, due to the connection through 1,3-dimethoxybenzene units, the skeleton structure of B1 shows stronger flexibility, with a small cavity and a stable propeller blade conformation. In addition, as Figure 1 As shown in b, it can be seen that there is a CO···π interaction between the two B1 molecules, and the distance is There are also CH···O hydrogen bond interactions, with distances of There is also a CH···π interaction with a distance of Due to these multiple non-covalent interactions, two B1 molecules are tightly bound together, showing centrosymmetry, and the center of symmetry is the central point of the B1 cavity ( Figure 1 (b)

[0046] Example 3

[0047] B1's adsorption performance test on iodine vapor:

[0048] 30 mg of B1 was added to the vials, which were then placed in a large sealed bottle containing 500 mg of iodine. The vials were then heated to 75 °C. As time went by, the color of B1 changed from yellow to black, and the saturated adsorption equivalent ( Figure 2 The equilibrium iodine uptake was calculated to be 69 wt%, i.e., one iodine molecule could adsorb an average of 4.2 iodine molecules.

[0049] By X-ray photoelectron spectroscopy (XPS), Figure 2 As shown in c, there are two obvious peaks after iodine adsorbs iodine vapor. The high-resolution XPS spectrum of iodine has two characteristic peaks at ≈631.73eV and ≈618.83eV, which belong to I 3d 3 / 2 and I 3d 5 / 2 ( Figure 2 (d) in the middle demonstrates the successful adsorption of iodine by B1.

[0050] Example 4

[0051] B1's adsorption performance test for iodide ions:

[0052] After adding 6 mg of B1 to KI solution (4 mL, 1.5 mM), the UV-visible spectrum at 226 nm corresponds to I - The absorbance of ions did not decrease, indicating that B1 had no effect on I - Ions have no adsorption properties.

[0053] When I3 - When 6 mg of B1 was added to the ion solution (4 mL, 0.25 mM, I2 / KI = 1:6), the - The concentration-related UV-visible peaks at 288 and 350 nm decreased significantly with increasing adsorption time ( Figure 2 At the same time, the color of the solution changed from yellow to colorless, and the adsorption efficiency reached 76% within 580 seconds, indicating that B1 could effectively adsorb I3 - Ions have a rapid and strong adsorption capacity ( Figure 3 In b). In addition, B1 adsorbs I3 - The X-ray photoelectron spectroscopy (XPS) after ionization showed two iodine 3d3 / 2 and 3d5 / 2 splitting peaks at 629.93 and 619.08 eV, indicating that I3- The ions were successfully adsorbed by B1 ( Figure 3 (c and d).

[0054] Example 5

[0055] B1 cycle performance test:

[0056] I3 - The specific adsorption process of ions is shown in Example 4.

[0057] Since B1 cannot adsorb I - By using sodium thiosulfate solution, I3 adsorbed in B1 - Restore to I - , so that I3 - Remove from B1.

[0058] After five adsorption-desorption cycles, the performance of B1 did not change at all, indicating its good stability. Figure 4 shown.

[0059] Example 6

[0060] B1 vs. I3 - Practical applications of ion adsorption:

[0061] like Figure 5 Shown: A cross-sectional area of ​​0.56 cm 2 The glass column was filled with a small piece of cotton, about 200 mg of B1 powder and a small amount of fine sand. Finally, the B1 powder on the wall of the glass column was compressed together with the small piece of cotton. - The solution was stirred at 1 mL min -1 The color of the solution changed from yellow to colorless when the solution passed through the glass column at a flow rate of 1.5 wt %. In addition, the UV-visible spectrum of the eluted solution showed no peaks at 288 and 350 nm, confirming the successful removal of I3 from the aqueous solution. - ,like Figure 6 shown.

Claims

1. A leaf aromatic hydrocarbon, characterized in that: It has the following molecular structure:

2. The method for synthesizing leaf aromatics according to claim 1, wherein: The following steps are involved: 1) 2,4-dimethoxybenzylamine and 1,2,4,5-benzenetetracarboxylic anhydride undergo imidization reaction to obtain an intermediate; 2) The intermediate undergoes condensation reaction with paraformaldehyde to obtain; The intermediate has the following molecular structure:

3. The method for synthesizing leaf aromatics according to claim 2, wherein: The molar ratio of the 2,4-dimethoxybenzylamine to the 1,2,4,5-benzenetetracarboxylic anhydride is 2 to 2.5:

1.

4. The method for synthesizing leaf aromatics according to claim 2 or 3, wherein: The conditions of the imidization reaction are: temperature of 100-120° C. and time of 8-16 hours.

5. The method for synthesizing leaf aromatics according to claim 2, wherein: The molar ratio of the intermediate to paraformaldehyde is 1:3-5, wherein the paraformaldehyde is measured based on the formaldehyde units it contains.

6. The method for synthesizing leaf aromatics according to claim 2 or 5, characterized in that: The condensation reaction conditions are: using boron trifluoride etherate as a catalyst, the temperature is room temperature, and the time is 10 to 20 minutes.

7. The use of a leaf aromatic hydrocarbon according to claim 1, characterized in that: As I2 or I3 - Adsorption material application.

8. The use of leaf aromatics according to claim 7, characterized in that: Applied to adsorb I2 vapor in air or I3 in aqueous solution - .

Images