A phenylazo phenol derivative, a lithium selective extraction composition and use thereof

Abstract

This invention discloses a phenylazophenol derivative, a lithium-selective extraction composition, and its application, belonging to the field of lithium-ion extraction technology. The invention provides a phenylazophenol derivative that replaces the rigid naphthalene ring in existing phenylazonaphthol derivatives with a more easily modifiable benzene ring. While retaining the phenolic hydroxyl-azo group co-coordination characteristics, it introduces electron-withdrawing substituents onto the phenolic hydroxyl-containing benzene ring, forming a local coordination environment in synergy with the phenolic hydroxyl and azo groups. Using the phenylazophenol derivative prepared by this invention as the main extractant in lithium-selective extraction significantly improves the extraction efficiency for Li-ion under low alkalinity conditions. + Extraction capacity and Li + / Na + It exhibits separation selectivity and effectively improves the oil solubility and phase separation behavior of the extractant, while inhibiting emulsification and the formation of a third phase.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion extraction technology, specifically to a phenylazophenol derivative, a lithium selective extraction composition, and its applications. Background Technology

[0002] With the continuous development and utilization of liquid lithium resources such as alkaline salt lake brines and lithium precipitation mother liquor, the efficient separation and recovery of lithium ions from high-salt, high-sodium, and complex coexisting ion systems has become an important research direction in the field of lithium resource extraction. For high-sodium lithium-containing mother liquors, the lithium ion content is usually low, while the sodium ion content is high, and the system often has a certain degree of alkalinity, making it difficult for Li... + / Na + The separation difficulty increases significantly. Existing research shows that the commonly used efficient lithium extraction routes in this type of system are mostly concentrated on β-diketones, phenolic ketones, their phosphine oxides, and their synergistic systems.

[0003] In existing technologies, phenylazonaphthol compounds, due to the simultaneous presence of azo nitrogen atoms and phenolic hydroxyl coordination sites in their molecules, have been used in studies of metal ion coordination and separation. For example, patent application CN112342406A discloses a method for extracting lithium from salt lake brine, using 1-phenylazo-2-naphthol as a hydrophobic extractant. Another example is a paper published in the *New Journal of Chemistry* entitled "The Enrichment of..." 7 The existing literature, “Li by Extraction with a Sudan I-Ionic Liquid System”, discloses a synergistic lithium extraction process using Sudan I, namely 1-phenylazo-2-naphthol, and a neutral ligand. The Sudan I-TOPO-xylene system has been reported to have lithium isotope separation effect.

[0004] However, lithium extraction using the known 1-phenylazo-2-naphthol as a lithium extractant, or the conventional synergistic system of 1-phenylazo-2-naphthol and TOPO for Li-extraction in salt lake brines, is not feasible. + / Na + During separation, the extraction process requires strong alkaline conditions (pH=13.8~14), and the alkali consumption during the extraction process is relatively high; the selective extraction effect of lithium ions in high sodium lithium-containing systems is still not good. Summary of the Invention

[0005] This invention provides a phenylazophenol derivative, a lithium selective extraction composition, and its application, aiming to solve the problems of high alkalinity dependence and insufficient lithium / sodium selectivity in existing phenylazonaphthol lithium extractants. This invention provides a phenylazophenol derivative in which a benzene ring skeleton replaces the traditional naphthyl ring skeleton, and electron-withdrawing substituents are introduced onto the benzene ring containing phenolic hydroxyl groups to form an azo-phenolic hydroxyl-electron-withdrawing group cooperative recognition unit.

[0006] The purpose of this invention is to provide a phenylazophenol derivative, wherein the general structural formula of the phenylazophenol derivative is: .

[0007] Wherein, R0 is selected from nitro, -CHO, C1~C6 alkyl acyl, C2~C6 alkenyl acyl, C2~C6 alkynyl acyl, C6~C 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 arylalkoxycarbonyl, C1~C6 alkoxy, C6~C 16 Aryloxy group or -P(=O)X2; X is a C1~C6 alkyl group, C6~C 10 Aryl, C1~C5 alkoxy or C6~C 10 Aryloxy.

[0008] R1, R2, and R3 are each independently selected from hydrogen atoms, halogens, nitro groups, cyano groups, C1-C6 haloalkyl groups, -CHO groups, C1-C6 alkyl acyl groups, C2-C6 alkenyl acyl groups, C2-C6 alkynyl acyl groups, and C6-C6 alkyl acyl groups. 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 aryl alkoxycarbonyl, C1~C6 alkoxy or C6~C 16 Aryloxy.

[0009] R1, R2, and R3 cannot all be hydrogen atoms at the same time.

[0010] R4 is a hydrogen atom, C1~C 10 Alkyl, C3-C8 cycloalkyl or C1-C 12 Alkyl group.

[0011] In a preferred embodiment, R0 is nitro, -CHO, C1~C3 alkyl acyl, C1~C3 alkoxy carbonyl, C1~C3 alkyl sulfonyl or -P(=O)X2, where X is C1~C3 alkoxy.

[0012] In a preferred embodiment, R0 is nitro, acetyl, methoxycarbonyl, methanesulfonyl, or -P(=O)(OCH3)2.

[0013] In a preferred embodiment, R1, R2, and R3 are each independently selected from C1-C3 fluoroalkyl, fluorine, nitro, cyano, or methanesulfonyl groups.

[0014] In a preferred embodiment, the phenylazophenol derivative is any one of the following compounds: .

[0015] A second object of the present invention is to provide a phenyl azophenol derivative as described in any of the above claims as a Li + Application of specifically selected master extractants.

[0016] A third objective of this invention is to provide a lithium selective extraction composition comprising a main extractant, a co-extractant, and a diluent, wherein the main extractant is a phenylazophenol derivative as described in any of the preceding claims.

[0017] In a preferred embodiment, the concentration of the phenylazophenol derivative is 0.01 mol / L to 1.0 mol / L based on the total volume of the lithium selective extraction composition, and the molar ratio of the phenylazophenol derivative to the co-extractant is 1:0.2 to 5.

[0018] In a preferred embodiment, the co-extractant is at least one of phosphonates, phosphate esters, quaternary ammonium salts, neutral oxygen-containing ligands, neutral nitrogen-containing ligands, and ionic liquids; the diluent is at least one of aromatic halogenated hydrocarbons, aromatic hydrocarbons, fatty alcohols, ketones, and ethers.

[0019] The fourth object of the present invention is to provide an application of the lithium selective extraction composition described in any of the above claims for the selective extraction of lithium ions from sodium-lithium aqueous solution; the application method is as follows: the lithium selective extraction composition is mixed with a sodium-lithium aqueous solution with a pH of 9-14 to perform lithium ion selective extraction.

[0020] In sodium-lithium aqueous solutions, the concentration of sodium ions is 0.01 mol / L to 4.0 mol / L, and the concentration of lithium ions is 0.01 mol / L to 1.5 mol / L.

[0021] This invention also provides a supported separation material, wherein the supported separation material is loaded with the aforementioned phenylazophenol derivative, and may be a microcapsule, polymer-encapsulated membrane, composite nanofiber membrane, supported liquid membrane, polymer-coated particles, or covalently grafted separation material. The functional component (phenylazophenol derivative) can be introduced through physical embedding, cross-linking fixation, covalent grafting, in-situ polymerization, ion imprinting, or core-shell confinement to reduce the loss of active components and improve cycling stability. It should be noted that the material protection object is also limited to systems loaded with phenylazophenol platform molecules, rather than a simple overlay of known Sudan-I material routes.

[0022] This invention also provides a lithium selective separation method, comprising the following steps: contacting a high-sodium lithium-containing feed solution with the lithium selective extraction composition or the supported separation material, so that Li... +The lithium is preferentially coordinated and transferred to the organic phase or the material phase of the lithium selective extraction composition; then, lithium is back-extracted and recovered using an acidic, hydrated carbonate or other suitable back-extraction system; and then the organic phase or material is regenerated and recycled.

[0023] The above-mentioned lithium selective separation method is preferably applied to lithium precipitation mother liquor, salt lake brine, or other high-Na solutions. + / Low Li + This system is particularly suitable for verifying the low-basicity, high-selectivity lithium recognition effect brought about by new substituents and conformational regulation.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: To address the problems of high alkalinity dependence and insufficient lithium / sodium selectivity in existing phenylazonaphthol lithium extractants (such as Sudan-I), this invention provides a phenylazonaphthol derivative with the following structural formula: It replaces the rigid naphthalene ring in the existing phenyl azo naphthol with a more easily modified benzene ring. While retaining the phenolic hydroxyl-azo group coordinating coordination characteristics, it introduces 2 to 4 identical or different electron-withdrawing substituents on the phenolic hydroxyl-containing benzene ring to form a local coordination environment in coordination with the phenolic hydroxyl and azo groups.

[0025] When the phenylazophenol derivative prepared in this invention was used as the main extractant for lithium selective extraction, compared with the control system of unsubstituted or weakly electron-donating substitution, the phenylazophenol derivative of this invention as the main extractant could significantly improve the extraction efficiency for Li under lower alkalinity conditions (pH 9-13.5). + Extraction capacity and Li + / Na + It exhibits separation selectivity and effectively improves the oil solubility and phase separation behavior of the extractant, while inhibiting emulsification and the formation of a third phase. Attached Figure Description

[0026] Figure 1 The images show the FT-IR spectra of the phenyl azophenol derivatives (monosubstituted) of Comparative Examples 1 to 6 and the phenyl azonaphthol derivative of Comparative Example 7, wherein HS0 is Comparative Example 7, HS1 is Comparative Example 1, HS2 is Comparative Example 2, HS3 is Comparative Example 3, HS4 is Comparative Example 4, HS5 is Comparative Example 5, and HS6 is Comparative Example 6.

[0027] Figure 2 The images show the FT-IR spectra of the phenyl azophenol derivatives (disubstituted) prepared in Examples 1 to 3 of this invention, where HS-D1 is Example 1, HS-D2 is Example 2, and HS-D3 is Example 3. Detailed Implementation

[0028] To enable those skilled in the art to better understand and implement the technical solutions of this invention, the invention is further described below with reference to specific embodiments. However, the embodiments are not intended to limit the invention. Unless otherwise specified, the following test methods and detection methods are conventional methods; unless otherwise specified, the reagents and raw materials are commercially available.

[0029] For the selective extraction of lithium ions in high-sodium lithium-containing systems, existing technologies employ 1-phenylazo-2-naphthol as a known lithium extractant, or use a conventional synergistic system of 1-phenylazo-2-naphthol and TOPO for lithium extraction from salt lake brines. + / Na + During separation, the extraction process requires strong alkaline conditions to function, resulting in high alkali consumption; the selective extraction effect of lithium ions in high-sodium lithium-containing systems remains unsatisfactory. Based on the above technical problems, this invention provides a phenylazophenol derivative and its synthesis method, as well as a lithium selective extraction system.

[0030] The technical solution of the present invention will be described in detail below.

[0031] This invention uses phenylazo-o-nitrophenol as the core skeleton and focuses on the molecular structure regulation and design based on the type, substitution position and structural characteristics of electron-withdrawing substituents and alkyl chains.

[0032] This invention provides a phenylazophenol derivative, wherein the phenylazophenol derivative is... ; Wherein, R0 is selected from nitro, -CHO, C1~C6 alkyl acyl, C2~C6 alkenyl acyl, C2~C6 alkynyl acyl, C6~C 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 arylalkoxycarbonyl, C1~C6 alkoxy, C6~C 16 Aryloxy group or -P(=O)X2, wherein X is selected from C1~C6 alkyl, C6 ... 10 Aryl, C1~C5 alkoxy or C6~C 10 Aryloxy.

[0033] For the substituent R0, this invention introduces an electron-withdrawing substituent at the ortho position of the phenolic hydroxyl group, thereby obtaining a phenyl azophenol derivative. This type of structure can form a "azo-phenolic hydroxyl-ortho electron-withdrawing group" synergistic recognition unit with the azo group and phenolic hydroxyl group, which is crucial for achieving Li + Recognition capability and Li+ / Na + The key structural basis for the order-of-magnitude improvement in selectivity. More preferably, when R0 is a nitro group, the nitro, azo, and phenolic hydroxyl groups in the resulting phenylazophenol derivatives collectively form an "azo-phenolic hydroxyl-ortho-nitro" synergistic recognition unit, thereby further improving the selectivity of Li. + Recognition capabilities and Li + Highly efficient selective extraction.

[0034] R1, R2, and R3 are each independently selected from hydrogen atoms, halogens, nitro groups, cyano groups, C1-C6 haloalkyl groups, -CHO groups, C1-C6 alkyl acyl groups, C2-C6 alkenyl acyl groups, C2-C6 alkynyl acyl groups, and C6-C6 alkyl acyl groups. 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 aryl alkoxycarbonyl, C1~C6 alkoxy or C6~C 16 Aryloxy.

[0035] R1, R2, and R3 cannot all be hydrogen atoms at the same time.

[0036] R4 is a hydrogen atom, C1~C 10 Alkyl, C3-C8 cycloalkyl or C1-C 12 Alkyl group.

[0037] For substituents R1, R2, and R3, two of R1, R2, and R3 are hydrogen atoms, one of R1, R2, and R3 is a hydrogen atom, or none of the three are hydrogen atoms.

[0038] When R0 is a nitro group, and two of R1, R2, and R3 are hydrogen atoms, that is, the hydroxyl-containing benzene ring in the structural formula of the phenyl azophenol derivative contains two electron-withdrawing substituents, the structural formula of the phenyl azophenol derivative is as follows: The phenylazophenol derivative may be one of the following compounds: , , , , , , , , , , .

[0039] When R0 is a nitro group, and one of R1, R2, and R3 is a hydrogen atom, that is, the hydroxyl-containing benzene ring in the structural formula of the phenyl azophenol derivative contains three electron-withdrawing substituents, the structural formula of the phenyl azophenol derivative is: or The phenylazophenol derivative may be one of the following compounds: , , , , .

[0040] When R0 is a nitro group, and R1, R2, and R3 are not hydrogen atoms, that is, when the hydroxyl-containing benzene ring in the structural formula of the phenyl azophenol derivative contains four electron-withdrawing substituents, the structural formula of the phenyl azophenol derivative is: The phenylazophenol derivative may be one of the following compounds: , , , , .

[0041] This invention, by introducing substituents with different electronic effects onto the aromatic ring, can utilize the push / pull electron effect to synergistically regulate the coordination microenvironment, thereby enhancing the O - –Li + The interaction enhances coordination stability. Simultaneously, the introduction of strong electron-withdrawing groups helps increase the acidity of the phenolic hydroxyl group and promotes deprotonation, thereby reducing the effective working basicity of the system; while alkyl chains of suitable length are beneficial for improving the oil solubility of the extractant and reducing its water solubility. The synergistic effect of these structural regulation strategies provides a systematic molecular design scheme for constructing phenyl azophenol lithium selective extractants with high selectivity and good stability.

[0042] This invention revolves around Sudan-I (1-phenylazo-2-naphthol, To address the bottlenecks of the HS-0 system (high basicity dependence, difficulty in deep functionalization of the rigid naphthalene ring skeleton, and limited structural extensibility), a molecular reconstruction strategy migrating from the naphthalene ring skeleton to the benzene ring skeleton is proposed. By adjusting the rigid naphthalene ring recognition platform to the more easily modified and electronically structured and conformationally regulated phenyl azophenol platform, while retaining the phenolic hydroxyl-azo group co-coordination characteristics, 2-4 electron-withdrawing substituents are introduced onto the phenolic hydroxyl-containing benzene ring to form a local coordination environment in synergy with the phenolic hydroxyl and azo groups.

[0043] When the phenylazophenol derivative prepared in this invention was used as the main extractant for lithium selective extraction, compared with the control system of unsubstituted or weakly electron-donating systems, the phenylazophenol derivative of this invention as the main extractant significantly improved the extraction efficiency for Li under lower alkalinity conditions.+ Extraction capacity and Li + / Na + The separation selectivity is improved, and the oil solubility and phase separation behavior of the extractant are effectively enhanced, while emulsification and third-phase formation are suppressed, enabling the extraction of Li under low alkalinity conditions. + Effective selective identification.

[0044] The technical effects of the present invention will be described below through the following embodiments and comparative examples.

[0045] Example 1 A method for synthesizing a phenyl azophenol derivative includes the following steps: S1, add aniline of Formula 1 (17.4 mmol, 1.00 eq) to 2M hydrochloric acid aqueous solution (25 mL) and stir to dissolve. Cool in an ice bath and control the temperature to not exceed 5°C. Dissolve pre-cooled sodium nitrite aqueous solution (NaNO2, 18.3 mmol, 1.05 eq) in 12 mL of deionized water and slowly add it dropwise to the above system at below 5°C over 10-15 min. After the addition is complete, continue stirring at below 5°C for 20-30 min to obtain the diazonium salt solution of Formula 2 (prepare fresh and store at low temperature).

[0046] S2, in a separate 500 mL three-necked flask, add deionized water (300 mL) and sodium hydroxide (35.0 mmol, 2.0 eq) sequentially. After stirring to dissolve, add 2-nitro-4-(trifluoromethyl)phenol (17.4 mmol, 1.00 eq) of Formula 3 to form a clear phenolate solution. Cool this solution to below 5 °C in an ice bath. Under vigorous stirring, slowly add the pre-cooled diazonium salt solution of Formula 2 (approximately 17.4 mmol) dropwise to the phenolate solution below 5 °C. The reaction system gradually darkens and a red solid precipitates. After the addition is complete, continue stirring the reaction below 5 °C for 2 hours.

[0047] S3, after the reaction is complete, concentrated hydrochloric acid is slowly added dropwise below 5℃ to adjust the pH of the system to 1-2 (carefully control the acidification rate to maintain the low temperature). After acidification, the solid is collected by filtration, washed three times with ice-cold deionized water (3×50mL), and dried in air to obtain the crude product. The crude product is purified by silica gel column chromatography (silica gel 200-300 mesh) using a gradient elution with dichloromethane / petroleum ether (v / v=1:9→1:1) to obtain a red solid, which is the target compound of formula 5, with a yield of 0.82g and a yield of 15.2%, denoted as HS-D1; the synthetic route is as follows:

[0048] .

[0049] Example 2 A method for preparing a phenyl azophenol derivative, prepared according to the method of Example 1, except that the 2-nitro-4-(methanesulfonyl)phenol of Formula 3 in Example 1 is replaced with an equimolar amount of 2-nitro-4-(trifluoromethyl)phenol of Formula 3 to obtain a compound of Formula 5, denoted as HS-D2.

[0050] The synthesis route in this embodiment is as follows: .

[0051] Example 3 A method for synthesizing a phenyl azophenol derivative includes the following steps: S1, add aniline (52 mmol, 1.00 eq) of Formula 1 to 75 mL of 6 M hydrochloric acid aqueous solution and stir to dissolve. Cool in an ice bath and control the temperature to not exceed 5 °C. Dissolve pre-cooled sodium nitrite aqueous solution (NaNO2, 53.6 mmol, 1.05 eq) in 108 mL of deionized water and slowly add it dropwise to the above system at below 5 °C over 30 min. After the addition is complete, continue stirring at below 5 °C for 20-30 min to obtain the diazonium salt solution of Formula 2 (prepare fresh and store at low temperature).

[0052] S2, in a separate 2000 mL three-necked flask, add 900 mL of deionized water and 105 mmol (2.0 eq) of sodium hydroxide, stirring until dissolved. Then add 51 mmol (1 eq) of 4-cyanophenol (Formula 3) to form a clear phenolate solution. Cool this solution to below 5 °C in an ice bath. Under vigorous stirring, slowly add 52 mmol of the pre-cooled diazonium salt solution (Formula 2) dropwise to the phenolate solution below 5 °C. The reaction system gradually darkens and a red solid precipitates, yielding the compound of Formula 4. After the addition is complete, continue stirring the reaction at below 5 °C for 2 h.

[0053] S3. After the reaction is complete, concentrated hydrochloric acid is slowly added dropwise below 5°C to adjust the pH of the system to 1-2 (care should be taken to control the acidification rate to maintain the low temperature). After acidification, the solid is collected by filtration and washed three times with ice-cold deionized water (3 × 50 mL), and dried in air to obtain the crude product. The crude product is purified by silica gel column chromatography (silica gel 200-300 mesh) with a gradient elution of dichloromethane / petroleum ether (v / v = 1:9 → 1:1) to give the compound of formula 5, designated as HS-6 (intermediate III), with a yield of 2.2 g and a yield of 18.8%.

[0054] S4: In a dry 100 mL three-necked flask, add HS-6 (9.8 mmol, 1.0 eq) prepared in S3 and glacial acetic acid (40 mL), and stir at room temperature until completely dissolved. Cool the reaction flask in an ice-water bath, and slowly add concentrated nitric acid (1.0 mL, 14.7 mmol, 1.5 eq) dropwise with stirring, controlling the dropping rate to keep the reaction solution temperature below 10 °C. After the addition is complete, remove the ice bath, slowly raise the temperature of the reaction system to 50 °C, and continue stirring for 6 h (monitor the reaction progress by TLC).

[0055] S5. After the reaction is complete, the reaction solution is slowly poured into 200 mL of ice water to quench the reaction, precipitating a solid. The aqueous phase is extracted with dichloromethane (3 × 200 mL) until the aqueous phase is colorless. The organic phases are combined and washed with water until neutral. The organic phase is dried over anhydrous sodium sulfate, and the solvent is removed by rotary evaporation to obtain the crude product. The crude product is further purified by silica gel column chromatography (silica gel 200-300 mesh) using a gradient elution of dichloromethane / petroleum ether (volume ratio 1:9 → 1:1). The target component is collected, dried, and the product of formula 6 is obtained, totaling 1.3 g, with a yield of 36.1%, denoted as HS-D3.

[0056] The synthesis route in this embodiment is as follows: .

[0057] Example 4 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-methylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2,4-nitrophenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, resulting in a derivative with the following structural formula: The compound is denoted as HS-D4.

[0058] Example 5 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-methoxyaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-fluorophenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is denoted as HS-D5.

[0059] Example 6 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-ethylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(formyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is denoted as HS-D6.

[0060] Example 7 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-ethylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(acetyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is designated as HS-D7.

[0061] Example 8 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-ethylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(benzoyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is designated HS-D8.

[0062] Example 9 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-ethylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(phenylacetyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is designated HS-D9.

[0063] Example 10 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-toluidine is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(phenoxycarbonyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is designated as HS-D10.

[0064] Example 11 A method for preparing a phenyl azophenol derivative, following the method of Example 1, except that an equimolar amount of p-propylaniline is used to replace the aniline of Formula 1 in Example 1, and an equimolar amount of 2-nitro-4-(benzyloxycarbonyl)phenol is used to replace the 2-nitro-4-(trifluoromethyl)phenol of Formula 3 in Example 1, yielding a derivative with the following structural formula: The compound is designated as HS-D11.

[0065] To further illustrate the technical effects of the present invention, a comparative example is also provided, as follows.

[0066] Comparative Example 1 A method for synthesizing a phenyl azophenol derivative includes the following steps: S1, aniline (17.4 mmol, 1.00 equiv) was dissolved in 2 M hydrochloric acid aqueous solution (25 mL) by stirring. The solution was then cooled in an ice bath, with the temperature controlled not exceeding 5 °C. Pre-cooled sodium nitrite aqueous solution (NaNO2, 18.3 mmol, 1.05 eq, dissolved in 12 mL deionized water) was slowly added dropwise to the above system over 10-15 min at below 5 °C. After the addition was complete, stirring was continued at below 5 °C for 20-30 min to obtain the diazonium salt solution of Formula 2 (prepared fresh and stored at low temperature).

[0067] S2, in a separate 500 mL three-necked flask, add deionized water (300 mL) and sodium hydroxide (35.0 mmol, 2.0 equiv) sequentially. After stirring to dissolve, add p-cresol (17.4 mmol, 1.00 equiv) of Formula 3 to form a clear phenolate solution. Cool this solution to below 5 °C in an ice bath. Under vigorous stirring, slowly add the pre-cooled diazonium salt solution of Formula 2 (approximately 17.4 mmol) dropwise to the phenolate solution below 5 °C. The reaction system gradually darkens and a red solid precipitates. After the addition is complete, continue stirring the reaction below 5 °C for 2 hours.

[0068] S3. After the reaction is complete, concentrated hydrochloric acid is slowly added dropwise below 5°C to adjust the pH of the system to 1-2 (care should be taken to control the acidification rate to maintain the low temperature). After acidification, the solid is collected by filtration and washed three times with ice-cold deionized water (3 × 50 mL). The solid is then dried in air to obtain the crude product. The crude product is purified by silica gel column chromatography (silica gel 200-300 mesh) with a gradient elution of dichloromethane / petroleum ether (v / v = 1:9 → 1:1) to give a red solid, which is the target compound of formula 5. The yield is 2.39 g, with a yield of 65.04%, and is designated as HS-1.

[0069] The above synthetic route is shown below: .

[0070] Comparative Example 2 A method for preparing a phenyl azophenol derivative, which is prepared according to the method of Comparative Example 1, except that the p-cresol of Formula 3 in Comparative Example 1 is replaced with an equimolar amount of p-nitrophenol of Formula 3 to obtain a compound of Formula 5, denoted as HS-2.

[0071] The synthesis route in this embodiment is as follows: .

[0072] Comparative Example 3 A method for preparing a phenyl azophenol derivative, prepared according to the method of Comparative Example 1, except that the p-cresol of Formula 3 in Comparative Example 1 is replaced with an equimolar amount of 4-fluorophenol of Formula 3 to obtain a compound of Formula 5, with a yield of 1.95 g and a yield of 49.6%, denoted as HS-3.

[0073] The synthesis route in this embodiment is as follows: .

[0074] Comparative Example 4 (HS-4) A method for preparing a phenyl azophenol derivative, which is prepared according to the method of Comparative Example 1, except that the p-cresol of Formula 3 in Comparative Example 1 is replaced with an equimolar amount of 4-trifluoromethylphenol of Formula 3, to obtain a compound of Formula 5, denoted as HS-4.

[0075] The synthesis route in this embodiment is as follows: .

[0076] Comparative Example 5 A method for preparing a phenyl azophenol derivative, prepared according to the method of Comparative Example 1, except that the p-cresol of Formula 3 in Comparative Example 1 is replaced with an equimolar amount of 4-(methanesulfonyl)phenol of Formula 3, to obtain a compound of Formula 5, with a yield of 1.21 g and a yield of 24.95%, denoted as HS-5.

[0077] The synthesis route in this embodiment is as follows: .

[0078] Comparative Example 6 A method for preparing a phenyl azophenol derivative, following the same steps S1-S3 as in Example 3, yielded a compound of formula 5 with a yield of 2.2 g and a recovery rate of 18.8%, designated as HS-6.

[0079] The synthesis route in this embodiment is as follows: .

[0080] Comparative Example 7 The 1-phenylazo-2-naphthol used in the method for extracting lithium from salt lake brine disclosed in the invention patent application with publication number CN112342406A is designated as HS-0.

[0081] The characterization spectral data of the phenyl azophenol derivatives prepared in the above examples are as follows.

[0082] NMR data of compound HS-D1 in Example 1: 1H NMR (600 MHz, CDCl3) δ7.94 (d, J=7.5Hz, 2H), 7.54 (dd, J=16.0,7.6 Hz, 3H), 7.48 (d,J=7.0 Hz, 1H), 7.16 (d,J=8.9 Hz,1H).HRMS (Q Exactive Orbitrap MS, APCI) m / z: calcd for C 13 H8O3F3N3(M+H)+:311.05; found: 311.05. NMR data of compound HS-D2 in Example 2: 1 H NMR(600 MHz, CDCl3) δ 7.94 (d, J=7.5Hz, 2H), 7.56 (dd, J=16.1, 8.1 Hz, 2H), 7.50-7.45 (m, 2H), 7.16 (d, J=8.4 Hz,1H),3.43(s,3H). HRMS (Q Exactive Orbitrap MS, APCI) m / z: calcd for C 15 H 15 O3N3S(M+H)+: 317.08; found: 317.08. NMR data of compound HS-D3 in Example 3: 1 H NMR (600 MHz, CDCl3) δ 8.26 (d, J=9.1 Hz, 1H), 7.93 (d, J = 4.8 Hz, 2H), 7.58 (d, J=5.9 Hz, 3H), 7.14 (d, J=9.1Hz, 1H). HRMS (Q Exactive Orbitrap MS, APCI) m / z: calcd for C 13 H8O3N4(M+H)+:268.06; found: 268.06. The following describes the selective extraction of lithium ions using the phenylazophenol derivatives prepared in Examples 1 to 11 of the present invention, Comparative Examples 1 to 6, and the phenylazonaphthol compound in Comparative Example 7.

[0083] 1. Extraction experimental method: Using the compounds prepared in the embodiments or comparative examples of this invention as the main extractant, 1.0 mmol of each of the following compounds were taken: HS-0 (Comparative Example 7), HS-1 (Comparative Example 1), HS-2 (Comparative Example 2), HS-3 (Comparative Example 3), HS-4 (Comparative Example 4), HS-5 (Comparative Example 5), HS-6 (Comparative Example 6), HS-D1 (Example 1), HS-D2 (Example 2), HS-D3 (Example 3), HS-D4 (Example 4), HS-D5 (Example 5), HS-D6 (Example 6), and HS- D7 (Example 7), HS-D8 (Example 8), HS-D9 (Example 9), HS-D10 (Example 10), and HS-D11 (Example 11) were each added to 50 mL centrifuge tubes with 2.0 mmol of the co-extractant trioctylphosphine oxide (TOPO). Then, 10 mL of diluent o-dichlorobenzene (DCB) was added to each centrifuge tube to dissolve the organic components and prepare the organic phase, thereby constructing 18 lithium selective extraction compositions. The extractant concentration in each lithium selective extraction composition was 0.10 mol·L⁻¹. -1 The molar ratio of the main extractant to the co-extractant is 1:2, and the ratio of O to A is 1:1.

[0084] Extraction experiments were conducted by adding 10 mL of simulated brine to each centrifuge tube. The simulated brine was an alkaline solution system with high sodium and low lithium content and a pH of 13, prepared from 0.02 mol / L LiCl, 0.02 mol / L NaCl, 0.10 mol / L KOH, and deionized water.

[0085] All extraction experiments were conducted in a constant temperature shaking incubator (ZQZY-88CY) at 25±1℃. Extraction was terminated after 15 min of shaking contact, followed by phase separation. The aqueous phase after extraction was diluted 50-fold, and the Li in the extract and back-extraction solution was... + with Na + The content was quantitatively determined using inductively coupled plasma optical emission spectrometry (ICP-OES, iCAPPROXP).

[0086] Table 1. Components of the lithium selective extraction compositions of phenylazophenol derivatives of the comparative examples of the present invention. Table 2. Components of the lithium selective extraction composition for phenyl azophenol derivatives in this invention. 2. Extraction and separation results: The electronic effects of substituents, including inductive and resonance effects, along with steric hindrance, collectively determine the effectiveness of azo extractants on Li. +Its coordination configuration and size recognition capabilities can therefore serve as one of the key parameters for molecular design and performance regulation.

[0087] (1) Monosubstituted p-azophenol Li + / Na + The effects of separation are shown in Table 1.

[0088] Table 3. Separation performance of the lithium selective extraction compositions of Comparative Examples 1 to 7 of the present invention. From Table 3 and Figure 2 It can be seen that unsubstituted HS-0 and weakly electron-donating HS-1 (-CH3) have a positive effect on Li. + The extraction capacity is relatively weak, with single-stage extraction rates of approximately 24.4% and 12.8%, respectively. Meanwhile, Li... + / Na + The separation coefficient is low, β Li / Na The values ​​are approximately 7.2 and 3.0, respectively. In contrast, after introducing strong electron-withdrawing groups, the Li in the system... + Extraction and Li + / Na + Significantly enhanced recognition was observed in the single-stage Li₂ of HS-2 (-NO₂), HS-4 (-CF₃), HS-5 (-SO₂CH₃), and HS-6 (-CN). + The extraction rates reached 94.9%, 95.4%, 95.3%, and 94.4%, respectively, corresponding to β... Li / Na The values ​​are approximately 163, 217, 293, and 166, respectively. HS-3(-F) exhibits only moderate Li... + Extraction capacity, E Li It is approximately 34.8%, although its β Li / Na The concentration was approximately 130, but significant emulsification and a third phase occurred during operation, hindering phase separation and reducing process operability. A comprehensive comparison revealed the substituent performance order to be -SO2CH3>-CF3>-CN>-NO2, indicating that a strong induced electron-withdrawing effect combined with moderate steric hindrance is beneficial for enhancing Li... + Internal coordination and inhibition of Na + Collected together.

[0089] (2) Disubstituted azophenols containing o-nitro groups for Li + / Na + The effects of separation are shown in Table 4.

[0090] The lithium selective extraction compositions prepared using the disubstituted phenylazophenol derivatives prepared in Examples 1 to 11 of this invention all showed good extraction effects on lithium, with an extraction rate E0. Li All can reach 70%~96%, separation factor β Li / NaThe range is 300~2100. The following uses Examples 1 to 3 as examples to illustrate the effect of lithium selective extraction.

[0091] Table 4. Separation performance of the lithium selective extraction compositions of Examples 1-3 of the present invention. From Table 4 and Figure 1 As shown, the lithium extraction rates (Ei) of the three disubstituted azophenol molecules HS-D1 (-CF3, -NO2), HS-D2 (-SO2CH3, -NO2), and HS-D3 (-CN, -NO2) prepared in Examples 1 to 3 of this invention are shown. Li The percentages were 95.7%, 95.5%, and 95.9%, respectively, and their Li + / Na + The separation factors were 1382, 439, and 2012, respectively. The separation factors of the monosubstituted compounds without nitro groups (HS-4 (-CF3), HS-5 (-MeSO2), and HS-6 (-CN)) were only 217, 293, and 166, respectively. Compared with the disubstituted molecules with nitro groups, HS-D1 (-CF3, -NO2), HS-D2 (-MeSO2, -NO2), and HS-D3 (-CN, -NO2), their separation performance was improved to 636%, 149%, and 1212%, respectively.

[0092] Figure 1 These are the FT-IR spectra of the phenylazophenol derivatives (monosubstituted) of Comparative Examples 1 to 6 and the phenylazonaphthol derivative of Comparative Example 7, wherein HS-0 is Comparative Example 7, HS-1 is Comparative Example 1, HS-2 is Comparative Example 2, HS-3 is Comparative Example 3, HS-4 is Comparative Example 4, HS-5 is Comparative Example 5, and HS-6 is Comparative Example 6. Figure 1 It can be seen that all compounds prepared in the comparative examples of this invention are within approximately 3020 cm⁻¹. -1 A characteristic absorption band appears at all locations, which can be attributed to the stretching vibration of the phenolic hydroxyl group OH under intramolecular hydrogen bonding. All derivatives show an absorption band at 1200 cm⁻¹. -1 ~1260cm -1 Stable absorption bands were observed in all ranges, which can be attributed to the ν(CO) vibration of the phenolic hydroxyl group, indicating that all compounds maintained the consistency of the benzene-azo-phenol skeleton structure. For HS-1 (-CH3), the absorption band at 2920 cm⁻¹ was observed. -1 An aliphatic ν(CH) absorption peak can be observed at approximately 1302 cm⁻¹. -1 The absorption band at this point is related to the coupled vibrations of the aromatic ring ν(CO) and the in-plane δ(CH). HS-2(-NO2) at 1503 cm⁻¹ -1A significant ν(NO2) absorption peak is observed at 1253 cm⁻¹. HS⁻³(-F) shows a peak at 1253 cm⁻¹. -1 Strong ν(CF) absorption was observed at 1100 cm⁻¹, and at 1100 cm⁻¹ -1 ~1150cm -1 The interval is accompanied by other characteristic peaks. HS-4(-SO2CH3) at 1317 cm⁻¹ -1 With 1100cm -1 The HS-5(-SO2CH3) exhibits a pair of characteristic absorptions at approximately 1350 cm⁻¹, which can be attributed to the C–F stretching vibration of the CF3 group. -1 With 1150cm -1 The presence of a double peak nearby corresponds to the asymmetric and symmetric stretching vibrations of SO. HS-6 (-C≡N) at 2235 cm⁻¹ -1 The infrared peaks exhibit a sharp ν(C≡N) characteristic peak. Based on the above infrared characteristic peaks, it can be confirmed that substituents such as -CH3, -F, -NO2, -CF3, -SO2CH3, and -CN have been successfully introduced into the target azo molecule.

[0093] Figure 2 These are the FT-IR spectra of the phenyl azophenol derivatives (disubstituted) prepared in Examples 1 to 3 of this invention, where HS-D1 is from Example 1, HS-D2 is from Example 2, and HS-D3 is from Example 3. Figure 2 It can be seen that all compounds prepared in Examples 1 to 12 of the present invention are at approximately 3100 cm⁻¹ -1 The presence of a characteristic absorption band at each location can be attributed to the stretching vibration of the phenolic hydroxyl group (OH) under intramolecular hydrogen bonding, at 1579 cm⁻¹. -1 A significant absorption peak for the nitro asymmetric stretching vibration is observed at 1390 cm⁻¹. -1 The peak at 1100 cm⁻¹ corresponds to the stretching vibration of the nitro group. HS-D1 shows a peak at 1100 cm⁻¹. -1 The characteristic absorption at this point can be attributed to the CF stretching vibration of the CF3 group. HS-D2(-SO2CH3) exhibits absorption at approximately 1320 cm⁻¹. -1 With 1080cm -1 The presence of a double peak nearby corresponds to the asymmetric and symmetric stretching vibrations at S=O. HS-D3 (-C≡N) is observed at 2240 cm⁻¹. -1 Furthermore, all derivatives exhibit a sharp (-C≡N) characteristic peak at 1200 cm⁻¹. -1 ~1260cm -1 Stable absorption bands were observed in all ranges, which can be attributed to the phenolic hydroxyl (CO) vibration, indicating that all compounds maintained the consistency of the azophenol-phenol skeleton structure. The combined infrared characteristic peaks confirm that substituents such as -NO2, -CF3, -SO2CH3, and -CN have been successfully introduced into the target azo molecule.

[0094] In summary, the introduction of two strongly electron-withdrawing substituents into the phenylazophenol skeleton in this invention helps to significantly improve the Li + / Na + Separation selectivity can serve as a feasible molecular engineering control strategy. Its effect may be related to the synergistic influence of substituents on the acidity and electronic structure of coordination sites, thereby promoting the formation of phenolic oxygen sites and enhancing Li... + The stability of inner-layer coordination, thereby suppressing Na+ in a strongly competing ion background. + Non-specific co-extraction of Li. The performance differences of different disubstituted combinations further illustrate that the electron-withdrawing strength and steric hindrance of the substituents need to be synergistically optimized. Among them, the -CN and -NO2 combination exhibits better selectivity under the conditions of this invention, indicating that controlling the steric volume of the substituents while maintaining a strong electron-withdrawing effect helps to achieve Li + with Na + Fine-grained identification and separation.

[0095] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A phenylazophenol derivative, characterized in that, The general structural formula of the phenylazophenol derivative is: ； Wherein, R0 is selected from nitro, -CHO, C1~C6 alkyl acyl, C2~C6 alkenyl acyl, C2~C6 alkynyl acyl, C6~C 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 arylalkoxycarbonyl, C1~C6 alkoxy, C6~C 16 Aryloxy group or -P(=O)X2; X is a C1~C6 alkyl group, C6~C 10 Aryl, C1~C5 alkoxy or C6~C 10 aryloxy; R1, R2, and R3 are each independently selected from hydrogen atoms, halogens, nitro groups, cyano groups, C1-C6 haloalkyl groups, -CHO groups, C1-C6 alkyl acyl groups, C2-C6 alkenyl acyl groups, C2-C6 alkynyl acyl groups, and C6-C6 alkyl acyl groups. 10 Aryl acyl, C7~C 14 Arylalkyl acyl, C1~C6 alkylsulfonyl, C6~C 10 arylsulfonyl, C1~C6 alkoxycarbonyl, C2~C6 olefinoxycarbonyl, C2~C6 alkynoxycarbonyl, C6~C 10 aryloxycarbonyl, C7~C 14 aryl alkoxycarbonyl, C1~C6 alkoxy or C6~C 16 aryloxy; R1, R2, and R3 cannot all be hydrogen atoms at the same time; R4 is a hydrogen atom, C1~C 10 Alkyl, C3-C8 cycloalkyl or C1-C 12 Alkyl group.

2. The phenylazophenol derivative according to claim 1, characterized in that, The R0 is nitro, -CHO, C1~C3 alkyl acyl, C1~C3 alkoxy carbonyl, C1~C3 alkyl sulfonyl or -P(=O)X2, where X is C1~C3 alkoxy.

3. The phenylazophenol derivative according to claim 2, characterized in that, The R0 is nitro, acetyl, methoxycarbonyl, methanesulfonyl, or -P(=O)(OCH3)2.

4. The phenylazophenol derivative according to claim 1, characterized in that, R1, R2, and R3 are each independently selected from C1-C3 fluoroalkyl, fluorine, nitro, cyano, or methanesulfonyl groups.

5. The phenylazophenol derivative according to claim 1, characterized in that, The phenylazophenol derivative is any one of the following compounds: .

6. A phenylazophenol derivative according to any one of claims 1 to 5 as a Li + Application of specifically selected master extractants.

7. A lithium selective extraction composition, comprising a main extractant, a co-extractant, and a diluent, characterized in that, The main extractant is a phenyl azophenol derivative as described in any one of claims 1 to 5.

8. The lithium selective extraction composition according to claim 7, characterized in that, The concentration of the phenylazophenol derivative is 0.01 mol / L to 1.0 mol / L based on the total volume of the lithium selective extraction composition, and the molar ratio of the phenylazophenol derivative to the co-extractant is 1:0.2 to 5.

9. The lithium selective extraction system according to claim 8, characterized in that, The co-extractant is at least one of phosphonates, phosphate esters, quaternary ammonium salts, neutral oxygen-containing ligands, neutral nitrogen-containing ligands, and ionic liquids; the diluent is at least one of aromatic halogenated hydrocarbons, aromatic hydrocarbons, fatty alcohols, ketones, and ethers.

10. The application of the lithium selective extraction composition according to any one of claims 7 to 9, characterized in that, Used for the selective extraction of lithium ions from sodium-lithium aqueous solutions; the application method is as follows: the lithium selective extraction composition is mixed with a sodium-lithium aqueous solution with a pH of 9-13.5 to perform selective extraction of lithium ions; In sodium-lithium aqueous solutions, the concentration of sodium ions is 0.01 mol / L to 4.0 mol / L, and the concentration of lithium ions is 0.01 mol / L to 1.5 mol / L.

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