Receptor for selective solid-liquid extraction of lithium halides to an organic phase and a method for selective solid-liquid extraction of lithium halides using this receptor

Abstract

A method for selective extraction of lithium halide from a solid phase into an organic phase, using a receptor that selectively binds lithium cations and halide anions, wherein the receptor is dissolved in an organic solvent or a mixture of organic solvents, in contact with the solid phase, which receptor reversibly binds a lithium halide ion pair to form a complex that is soluble in the organic solvent or the mixture of organic solvents, wherein lithium halide is isolated by a back- extraction of a lithium halide ion pair into an aqueous phase, resulting in the dissociation of the complex and the transfer of the lithium halide to the aqueous phase while the free receptor remains in the organic phase or precipitates. The solid extraction product, containing the lithium halide is isolated after separation of the aqueous phase from the organic phase and evaporation of water from the aqueous solution thus obtained, or by precipitation in the form of a poorly soluble salt.

Description

[0001] Receptor for selective solid-liquid extraction of lithium halides to an organic phase and a method for selective solid-liquid extraction of lithium halides using this receptor

[0002] An subject of the invention is an ion pair binding receptor for lithium halides, and the use of this receptor for selective solid-liquid extraction of lithium halides from a solid phase to an organic phase, in the presence of halides of other alcali metals.

[0003] One of the key chemical elements for the development of modern technology is lithium. Its numerous applications include medicine and use in the treatment of mental disorders [Eur. j. Pharmacol. 740 (2014) 464; Chem. Rev. 99 (1999) 2659], industrial application in ceramics and glass production [Chem. Lett. 72 (2008) 862], fusion energy [ / . Fusion Energy 14 (1995) 329; Rev. Mod. Plasma Phys. 7 (2023)] and lithium-ion battery technology [Nature 451 (2008) 652; ACS Energy Lett. 6 (2021) 621; Adv. Energy, Mater. 11 (2021) 2102028], Electrochemical applications in particular have resulted in a significant increase in demand for lithium in recent years.

[0004] Lithium is traditionally extracted from minerals such as spodumene (LiAISiiOs) and petalite (LiAISi40io), as well as from mineral springs and saline basins rich in halide salts, found mainly in South America [Ore Geology Reviews 48 (2012) 55; Geology Today 36 (2020) 192]. Due to limited natural resources and the high costs of conventional lithium production methods, ecological alternative methods are being sought, which include the recovery of lithium from spent lithium-ion batteries [ / . Mater. Sci. 56 (2021) 16; Curr. Opin. Electrochem. 32 (2022) 101087; Sust. Mater. Tech. 17 (2019) e00087; Green. Chem. 22 (2020) 7585; Mater. Adv., 2 (2021) 3234; Desalination 359 (2015) 59] or its extraction from seawater [Sep. Purif. Tech. 172 (2017) 388], It is estimated that seawater contains a total of up to 180 billion tonnes of lithium, however, due to its extremely low concentration (approx. 0.2 ppm; for comparison, NaCI content is approx. 77800 ppm) and the lack of an efficient method of its extraction, obtaining lithium from seawater is currently completely uneconomic. Lithium extraction from alternative sources may be facilitated by the use of receptors capable of solid-liquid extraction (SLE) or liquid-liquid extraction (LLE). Ion-pair receptors are known that contain domains that simultaneously bind anions and cations, which give hope for the developing an efficient method for extracting lithium halides from seawater, as there is no problem of receptor competition with the counterion [Chem. Soc. Rev. 39 (2010) 3784; Angew. Chem. Int. Ed. 51 (2012) 2; Chem. Rev. 119 (2019) 9753; ChemPlusChem 85 (2020) 1824],

[0005] A macrocyclic ion-pair receptor capable of binding and extracting lithium bromide by solid-liquid extraction (SLE) is known [ / norg. Chem. 43 (2004) 7617], In later years, a number of macrocyclic ion- pair receptors were also developed, capable of extracting lithium salts from solid and aqueous solutions [ / . Am. Chem. Soc. 138 (2016) 9779; Angew. Chem. Int. Ed. 57 (2018) 11924; Org. Chem. Front. 9 (2022) 6888], It has also been confirmed that such receptors can be immobilised on polymeric substrates [ / . Am. Chem. Soc. 143 (2021) 20403; J. Mater. Chem. A. 10 (2022) 14788], Furthermore, examples of tripodal receptors have been developed to recognise lithium salts [Chem. Sci. 4 (2013) 585; Eur. j. Org. Chem. 2022 (2022) e202200808]. There is also a known receptor capable of extracting lithium chloride and lithium bromide from aqueous solutions into an organic phase, demonstrating the possibility of isolating the extracted lithium in the form of IJ2CO3 [Chem. Commun. 56 (2020) 10541], To the best of our knowledge, almost all receptors capable of selective and efficient extraction of lithium halides have multimacrocyclic structures, which are disadvantageous due to cumbersome synthesis and low yields of the macrocyclization step. To date, no low-cost ion-pair receptor capable of efficiently and selectively binding lithium halides has been developed.

[0006] Neutral (electrically inert) ion-pair receptors capable of simultaneously binding cations and anions are known, containing a squaramide group binding anions via amide groups and a crown ether group binding alcali metal cations [Chem. Sci. 10 (2019) 9542], These receptors are capable of coordinating ion pairs involving oxoanions and alcali metal cations, particularly sodium sulphate and potassium sulphate. Ion pair receptors containing a squaramide group to bind anions and a crown ether group to bind alcali metal cations are also known, using an amino acid platform [New j. Chem. 40 (2016) 7190], These receptors are capable of coordinating ion pairs in acetonitrile and of extracting chloride salts associated with a lipophilic cation from an aqueous to an organic phase. Neutral receptors containing a squaramide group, binding anions, and a benzo-15-crown-5 ether group for binding alkali metal cations are also known, [ / norg. Chem. 57 (2018) 12941], These receptors are designed to remove sodium chloride from the aqueous phase into nitrobenzene by extraction, but are unable to selectively bind lithium halides. There is an unmet need to develop low-cost and easy-to-manufacture ion-pair receptors capable of selectively, efficiently and reversibly binding lithium halides to form complexes that are soluble in organic solvents, and to develop a protocol for extraction of lithium halides from a solid or aqueous phase to an organic phase using these receptors, effective in the presence of halides of other alcali metals. The present invention solves the nuisances known from the state of the art.

[0007] Summary of the Invention

[0008] A receptor for selective extraction of lithium halides from a solid phase having an amide domain coordinating anions and a crown domain coordinating cations, characterized in that it has within one molecule a halide anion binding domain and a lithium cation binding domain, forming a structure with the general formula: wherein the squaramide group is capable of reversibly binding halide anions through their coordination with the protons of the amide groups, the aryl group with the crown substituent (Ar- Y) is capable of reversibly binding lithium cations through their coordination with the lone electron pairs of the oxygen atoms of the ether group, and the aryl group of with the substituent (Ar-X) increases the lipophilicity of the receptor, which receptor has the ability to selectively extract lithium halides in the presence of halides of other alcali metals from a solid phase to an organic phase, preferably immiscible with water, is soluble in organic solvents or mixtures thereof, preferably immiscible with water, and is capable of forming a complex with a lithium halide ion pair, soluble in organic solvents or mixtures of organic solvents, preferably immiscible with water.

[0009] According to the invention, the crown substituent (Y) of the benzocrown group (Ar-Y) is a 9-crown- 3 ether linked to a benzene ring, or a 12-crown-4 ether linked to a benzene ring, or a 15-crown-5 ether linked to a benzene ring, or an 18-crown-6 ether linked to a benzene ring.

[0010] Preferably, the (Ar-X) substituted aryl group possess electron-withdrawing groups while retaining a lipophilic character, preferably having (X) substituents such as: -F, -CF3, -NO2, -COOR, -CONR’R” or -SOiNR’R”, preferably -SOiNR’R” or -CONR’R”, wherein R, R' and R" are aliphatic chains of 1-6 carbon atoms, aryl groups or hydrogen. Alternatively, the substituted (Ar-X) aryl group has electrondonating or electron-neutral properties while retaining a lipophilic character, preferably having substituents (X) such as -R or -OR, wherein R represents aliphatic chains having 1-6 carbon atoms, aryl groups or hydrogen.

[0011] According to the invention, the receptor is soluble in organic solvents immiscible with water, preferably in chloroform, dichloromethane, alkyl esters, aryl esters, alkyl ethers, aryl ethers, toluene and nitrotoluene, or in water-miscible organic solvents, preferably in acetonitrile, methanol, ethanol and propan-2-ol, or any liquid alcohol or derivative thereof, or in mixtures of these solvents. The receptor is capable of being regenerated by washing it or its solution with water, preferably pure water, most preferably distilled or deionised water, optionally with the addition of methanol, and by subsequent evaporating the solvent. Preferably, the receptor for selective extraction of lithium halides from a solid phase according to the invention adopts one of the molecular structures I, II, III or IV:

[0012] A method for selective extraction of lithium halides from a solid phase into an organic phase, using a receptor that selectively binds lithium cations and halide anions, is characterised in that it uses the receptor as described above, preferably with structure I, II, III or IV, dissolved in an organic solvent or a mixture of organic solvents, being in the contact with the solid phase from which the extraction is carried out, which receptor reversibly binds a lithium halide ion pair to form a complex which is soluble in an organic solvent or mixture of organic solvents, wherein the lithium halide is isolated by a back-extraction of the lithium halide ion pair into an aqueous phase, which results in the dissociation of the complex and the transfer of the lithium halide to the aqueous phase while the free receptor remains in the organic phase or precipitates, and the solid extraction product, containing the lithium halide, is obtained after separation of the aqueous phase from the organic phase and evaporation of the water from the aqueous solution thus obtained or, alternatively, after precipitation of the lithium salt in the aqueous layer as a poorly soluble salt such as lithium carbonate.

[0013] Preferably, the extraction is carried out in a stationary mode, in which the main extraction stage can be distinguished, i.e. saturation of the receptor solution with the lithium halide, the filtration stage, i.e. the separation of the receptor complex solution with the lithium halide from the solid salt, and the back-extraction stage, i.e. the dissociation of the receptor complex with the lithium halide as a result of the contact of the organic phase with the aqueous phase.

[0014] Alternatively, the extraction is carried out in a continuous mode, wherein the solid phase at the bottom of the vessel is in the constant contact with the receptor solution in an water-immiscible organic solvent, that in turn is covered with an aqueous solution, and the receptor transfers the lithium halide ion pair from the solid salt phase through organic phase to the aqueous solution. According to the invention, the extraction from the solid phase is repeated until a solid lithium halide of satisfactory purity is obtained. The regeneration of the receptor is carried out by washing with water, preferably with pure water, most preferably with distilled water or deionised water, optionally with the addition of methanol, and then evaporating the solvent.

[0015] Preferably, the organic solvent or mixture of organic solvents used is not miscible with water and forms two phases upon the contact with the aqueous solution, wherein during the back-extraction of the lithium halide into the aqueous phase, the complex of the receptor with the lithium halide ion pair dissociates, wherein the lithium halide passes into the aqueous phase and the receptor remains dissolved in the organic phase, wherein preferably the organic phase is denser than the aqueous phase, preferably the organic solvent or the mixture of organic solvents comprises chloroform, dichloromethane, an alkyl ester, an aryl ester, an alkyl ether, an aryl ether, toluene or nitrotoluene.Alternatively, the organic solvent or the mixture of organic solvents used is miscible with water, wherein during the back-extraction process of the lithium halide into the aqueous phase, the receptor complex with the lithium halide ion pair dissociates, wherein the lithium halide remains dissolved in the liquid (aqueous-organic) phase and the receptor is precipitated as a precipitate, wherein the organic solvent or mixture of organic solvents preferably comprises acetonitrile, methanol, ethanol or 2-propanol or any liquid alcohol or derivatives thereof.

[0016] The receptor, according to the invention, exhibits the ability to selectively and reversibly bind lithium halides in the presence of halides of other alcali metals. This receptor can be successfully used for the efficient extraction of lithium halides from a solid phase into an organic phase, preferably immiscible with water, most preferably chloroform or dichloromethane, even from samples of natural origin containing mixtures of halides of different alcali metals and from waste subjected to recycling.

[0017] The receptor for selective extraction of lithium halides from a solid phase into an organic phase and the method for selective extraction of lithium halides from a solid phase using this receptor are described in detail below, with reference to the attached drawing, in which:

[0018] Fig. 1 shows structural formulae of the receptor according to the invention with the general form of the aryl group with a substituent (X) and with specified variants of the benzocrown group (ArY) structure containing 9-crown-3, 12-crown-4 ether, 15-crown-5 ether or 18-crown-6 ether;

[0019] Fig. 2 shows structural formulae of the receptor according to the invention with the general form of a benzocrown group (ArY) and with specified variants of an aryl group with the substituent (X) having preferred electron-withdrawing characteristics, i.e. -F, -CF3, -NO2, - COOR, -CONR’R” or -SOiNR’R”, wherein the aryl group may have 1-5 substituents, and R, R’ and R” are aliphatic chains with 1-6 carbon atoms, aryl groups or hydrogen,

[0020] Fig. 3 shows structural formulae of the receptor according to the invention, with the general form of the benzocrown group (ArY) and with detailed variants of the structure of the aryl group with a substituent (X) with electron-neutral or electron-donating properties, i.e. -R or -OR, wherein R represents aliphatic chains with 1-6 carbon atoms, aryl groups or hydrogen;

[0021] Fig. 4 shows a scheme for the synthesis of particularly preferred receptor variants (I, II, III, IV) and a reference receptor lacking a crown ether group;

[0022] Fig. 5 shows the structural formulae of particularly preferred receptor structural variants (I, II, III, IV) according to the invention containing a -SOiN^H^i group as a substituent (X) in the aryl group (ArX) and the benzocrown group (ArY) containing a 9-crown-3-ether, a 12- crown-4-ether, a 15-crown-5-ether or a 18-crown-6-ether;

[0023] Fig. 6 shows a structural formula of a reference receptor containing a group -SOiN^H^i as a substituent (X) in the aryl group (ArX) and a phenyl group with two methoxy substituents in place of the benzocrown group (ArY) of the receptor according to the invention;

[0024] Fig. 7 shows the1H NMR spectrum of the receptor in the preferred structural variant I, obtained in Example 2;

[0025] Fig. 8 shows the13C NMR spectrum of the receptor in the preferred structural variant I, obtained in Example 2;

[0026] Fig. 9 shows the1H NMR spectrum of the receptor in the preferred structural variant II, obtained in Example 3;

[0027] Fig. 10 shows a13C NMR spectrum of the receptor in the preferred structural variant II, obtained in Example 3;

[0028] Fig. 11 shows the1H NMR spectrum of the receptor in the preferred structural variant III, obtained in Example 4;

[0029] Fig. 12 shows the13C NMR spectrum of the receptor in the preferred structural variant III, obtained in Example 4;

[0030] Fig. 13 shows the1H NMR spectrum of the receptor in the preferred structural variant IV, obtained in Example 3; Fig. 14 shows the13C NMR spectrum of the receptor in the preferred structural variant IV, obtained in Example 5;

[0031] Fig. 15 shows the1H NMR spectrum of the reference receptor obtained in Example 6;

[0032] Fig. 16 shows the13C NMR spectrum of the reference receptor obtained in Example 6;

[0033] Fig. 17 shows the ion chromatogram of the aqueous solution obtained by the back- extraction of alkali metal halides with deionized water from a chloroform solution of receptor complex I after extraction from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI, according to the procedure presented in Example 7. The numerical results are presented in Table 1;

[0034] Fig. 18 shows the ion chromatogram of the aqueous solution obtained by the back- extraction of alkali metal halides with deionized water from a chloroform solution of receptor complex II after extraction from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI, according to the procedure presented in Example 7. The numerical results are presented in Table 1;

[0035] Fig. 19 shows the ion chromatogram of the aqueous solution obtained by the back- extraction of alkali metal halides with deionized water from a chloroform solution of receptor complex III after extraction from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI, according to the procedure presented in Example 7. The numerical results are presented in Table 1;

[0036] Fig. 20 shows the ion chromatogram of an aqueous solution obtained by the back-extraction of alkali metal halides with deionized water from a chloroform solution of receptor complex IV after extraction from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI, according to the procedure presented in Example 7. The numerical results are presented in Table 1;

[0037] Fig. 21 shows the ion chromatogram of an aqueous solution obtained by the back-extraction of alkali metal halides with deionized water from a chloroform solution of the reference receptor complex (REF) after extraction from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI, according to the procedure presented in Example 7. The numerical results are presented in Table 1;

[0038] Fig. 22 shows a compilation of the partial1H NMR spectra of receptor II in deuterated acetonitrile (CD3CN) obtained during the titration with LiBr solution, showing, among others, a shift of the pair of amide proton signals in the squaramide group (ca. 8.45 ppm in the free receptor; ca. 11.2 ppm in the saturated receptor) as a result of the binding of the LiBr ion pair by this receptor;

[0039] Fig. 23 shows a compilation of the partial1H NMR spectra of receptor II in deuterated acetonitrile (CD3CN) obtained during the extraction experiments with the solid alkali metal chloride salts (Example 9), showing the shift of protons signals in the squaramide group and signals originating from aromatic protons in the spectra of the solution after extraction with solid LiCI, NaCI and KCI, as well as after the extraction with a solid equimolar mixture of LiCI, NaCI and KCI, relative to the spectrum of free receptor II, wherein the similarity of the spectra of receptor's solutions after the LiCi and after the extraction with the solid mixture of LiCI, NaCI and KCI, indicates selective binding of the LiCi by this receptor, wherein: a) the1H NMR spectrum of free receptor II solution in CD3CN, b) the1H NMR spectrum of receptor II solution in CD3CN after the extraction with LiCi; c) the1H NMR spectrum of receptor II solution in CD3CN after the extraction with NaCI; d) the1H NMR spectrum of receptor II solution in CD3CN after the extraction with KCI; e) the1H NMR spectrum of receptor II solution in CD3CN after the extraction with a mixture of LiCi, NaCI and KCI;

[0040] Fig. 24 presents a compilation of the partial1H NMR spectra of receptor II in deuterated acetonitrile (CD3CN), obtained during the extraction experiments with the solid alkali metal chloride salts (Example 9), which shows a shift of the signals originating from the protons of the crown ether unit in the spectra of the solution after the extraction with solid LiCi, NaCI and KCI, as well as after the extraction with a solid equimolar mixture of LiCi, NaCI and KCI relative to the spectrum of the free receptor II, wherein the similarity of the spectra of receptor's solutions after the LiCi and after the extraction with the solid mixture of LiCi, NaCI and KCI, indicates selective binding of the LiCi by this receptor, wherein: a) the1H NMR spectrum of the free receptor II solution in CD3CN, b) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with LiCi; c) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with NaCI; d) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with KCI; e) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with a mixture of LiCI, NaCI and KCI;

[0041] Fig. 25 presents a compilation of the partial1H NMR spectra of receptor II in deuterated chloroform (CDCh), obtained during the extraction experiments with the solid alkali metal chloride salts (Example 10), which shows a shift of the pair of proton signals in the squaramide group and signals originating from the aromatic protons in the spectra of the solution after the extraction with solid LiCI, NaCI and KCI, as well as after the extraction with a solid equimolar mixture of LiCI, NaCI and KCI, relative to the spectrum of the free receptor II, wherein the similarity of the spectra of receptor's solutions after the LiCI and after the extraction with the solid mixture of LiCI, NaCI and KCI, indicates selective binding of the LiCI by this receptor, wherein: a) the1H NMR spectrum of the free receptor II solution in CD3CN, b) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with LiCI; c) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with NaCI; d) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with KCI; e) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with a mixture of LiCI, NaCI and KCI;

[0042] Fig. 26 presents a compilation of the partial1H NMR spectra of receptor II in deuterated chloroform (CDCI3) obtained during the extraction experiments with the solid alkali metal chloride salts (Example 10), which shows a shift of the signals originating from the protons of the crown ether unit in the spectra of the solution after the extraction with solid LiCI, NaCI and KCI, as well as after the extraction with a solid equimolar mixture of LiCI, NaCI and KCI, relative to the spectrum of the free receptor II, wherein the similarity of the spectra of receptor's solutions after the LiCI and after the extraction with the solid mixture of LiCI, NaCI and KCI, indicates selective binding of the LiCI by this receptor, wherein: a) the1H NMR spectrum of the free receptor II solution in CD3CN, b) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with LiCI; c) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with NaCI; d) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with KCI; e) the1H NMR spectrum of the receptor II solution in CD3CN after the extraction with a mixture of LiCI, NaCI and KCI;

[0043] Detailed description of the Invention

[0044] The invention relates to an ion pair receptor for selective extraction of lithium halides from a solid phase into an organic phase. Furthermore, the invention relates to the use of this receptor for extraction of lithium halides from a solid phase into an organic phase in the presence of halides of other alcali metals.

[0045] Receptor for selective extraction of lithium halides

[0046] The receptor, according to the invention, contains a halide anion-binding group (domain) and a lithium cation-binding group (domain), wherein a complex formed after reversible binding of a lithium halide ion pair remains soluble in organic solutions over a wide range of concentrations, so that it is possible to carry out extraction process from a solid phase into a liquid organic phase, preferably, immiscible with water, and thus efficiently obtain lithium halides, especially lithium chloride and lithium bromide. The general scheme of the structure of the receptor according to the invention is presented below: wherein the central group of squaramide (amide domain) is capable of binding halide anions through their coordination with the protons of the amide groups, the benzocrown group Ar-Y (crown domain) is capable of binding lithium cations through their coordination with the lone electron pairs of the oxygen atoms in the ether group, and the aryl group Ar-X increases the lipophilicity of the receptor.

[0047] The receptor and its complexes with a lithium halide ion pair, according to the invention, are insoluble in water, which enables hydrolysis of a receptor complex with lithium halides upon contact with an aqueous phase, with a simultaneous back-extraction of lithium halides into the aqueous phase.

[0048] Preferably, the receptor and its complexes with a lithium halide ion pair are soluble in water- immiscible organic solvents or mixtures of water-immiscible organic solvents, which provides for ease of recovery of the receptor during the back-extraction of the lithium halide into the aqueous phase, since it allows for free receptor to remain in the organic phase. Preferably, the receptor is soluble in chloroform, dichloromethane, alkyl esters, aryl esters, alkyl ethers, aryl ethers, toluene and nitrotoluene, or mixtures thereof, and most preferably in chloroform. In order to facilitate convenient continuous extraction, the organic solvent or mixture of organic solvents is preferably denser than water.

[0049] Alternatively, the receptor and its complexes with a lithium halide ion pair, according to the invention, are soluble in water-miscible organic solvents or mixtures of water-miscible organic solvents, which causes that during the back-extraction process of lithium halides into an aqueous phase, the complex of the receptor with the lithium halide ion pair dissociates, wherein the lithium halide remains dissolved in the liquid phase (aqueous-organic) and the receptor precipitates as a precipitate. Preferably, the receptor is soluble in acetonitrile, methanol, ethanol, 2-propanol or any liquid alcohol or its derivative, as well as in mixtures of these solvents. It is also possible to use a mixture of organic solvents miscible and immiscible with water.

[0050] The halide anion-binding domain is an squaramide unit (squaramide domain) coordinating anions via the amide groups that interact with the lone electron pairs of halide ions. The strength of the halide anion binding by the amide groups of the squaramide is additionally increased by their substitution with substituents increasing the acidity of the amide protons (an aryl group with an X substituent and a benzocrown group Ar-X complexed with a lithium cation) in comparison to the unsubstituted squaramide. These substituents, in general, reduce the electron density in the squaramide group, which results in increased acidity of the protons of its amide groups.

[0051] The lithium cation-binding domain is a crown ether (Y), which is part of a benzo-crown substituent (Ar-Y) at a squaramide, wherein the crown ether is linked to the squaramide via an aromatic ring. The crown ether ring, according to the invention, has from three to six oxygen atoms, which corresponds to four possible receptor structural variants, containing one of the following crown groups: a 9-crown-3-ether, a 12-crown-4-ether, a 15-crown-5-ether and a 18-crown-6-ether. The structural formulae of these receptor variants are presented below:

[0052] The selectivity of a lithium halide ion pair binding is significant compared to ion pair binding of halides of heavier alkali metals. Unexpectedly, selective binding of lithium halides, even by the receptors according to the invention containing the crown domain, classically seen as preferring the coordination of sodium cations (a 15-crown-5 ether as in structure III) or potassium cations (a 18- crown-6 ether as in structure IV), has been observed. It has also been observed that a receptor with the crown domain perceived as too small to coordinate lithium cations (a 9-crown-3 ether as in structure I) also binds lithium halide ion pairs. The use of the receptor in the preferred structural variants I, II, III and IV allows for selective extraction of lithium halides even in the presence of halides of heavier alkali metals. Exemplary experimental data on the selectivity of alkali metal halide binding are presented in the embodiment (Example 7, Table 1).

[0053] The crown ether-containing group (Ar-Y), as such, when attached to the amide group of the squaramide, does not increase the acidity of the protons of the amide group. However, the strength of this interaction increases significantly upon binding of the cation by the crown ether. Due to this effect, simultaneous binding of cations by the group of the same receptor molecule increases the binding strength of the anion. The aryl group with the substituent (Ar-X), constituting a substituent of the amide group of the squaramide, is intended to increase the lipophilicity of the entire receptor, thereby facilitating the solubility of the receptor and its complex with a lithium halide ion pair in organic solvents. In addition, preferably, the substituents (X) are intended to increase the acidity of the amide protons by reducing electron density on the aryl ring (i.e. X substituent has electronwithdrawing characteristics), and thus from the squaramide group, which increases its ability to coordinate halide anions, while maintaining the lipophilic character of the entire Ar-X group. Preferably, the receptor possess substituents (X) such as: -F, -CF3, -NO2, -COOR, -CONR’R” or - SOiNR’R”, most preferably -SOiNR’R” or -CONR’R”, wherein R, R’ and R” are aliphatic chains of 1-6 carbon atoms, aryl groups or hydrogen. The structural formulae of these receptor variants are presented below: The aryl group can have from 1 to 5 substituents (n = 1-5) (Ar-X) in any positions and combinations (including combinations of electron-withdrawing substituents with electron-donating or electronneutral substituents), since the chemical nature (electron-withdrawing) of these substituents is far more important for increasing the acidity of the amide protons in the squaramide group than their position. Nevertheless, it is preferred to use ArX groups: with five -F substituents (pentafluorobenzyl group), or with two -CF3 substituents at the meta positions, or with one -NO2 substituent at the para position, or with two -COOR substituents at the meta position, or with two -CONR’R” substituents at the meta position, or with one -SOiNR’R” substituent at the para position.

[0054] According to the invention, it is possible to use substituents (X) with electron-donating (which increase electron density in the squaramide group) or electron-neutral (which do not change electron density in the squaramide group) properties, retaining lipophilic characteristics. For example, it is possible to use substituents (X) such as -R or -OR, wherein R represents aliphatic chains with 1-6 carbon atoms, aryl groups or hydrogen. The aryl group can have from 1 to 5 substituents (n = 1-5) (Ar-X) in any positions and combinations (including combinations of electrondonating and electron-neutral substituents with electron-withdrawing substituents), as the chemical nature (electron-donating or electron-neutral) of these substituents is definitely more important than their position. Such receptors, due to the decrease in the acidity of amide protons in the squaramide group (receptor with electron-donating substituents X) or the lack of influence on the acidity of these protons (receptor with electron-neutral substituents X), are characterized by a lower efficiency of lithium halide extraction from a solid phase to an organic phase compared to the receptors having substituents (X) with electron-withdrawing characteristics. The structural formulae of these receptor variants are presented below:

[0055] According to the invention, the receptor for selective extraction of lithium halides from a solid phase, according to the invention, preferably adopting one of the molecular structures I, II, III or IV, wherein the aryl group (ArX) has one -SOiN^H^ substituent at the para position and the benzocrown group (ArY) has a 9-crown-3-ether, a 12-crown-4-ether, a 15-crown-5-ether or a 18- crown-6-ether, respectively:

[0056] During the simultaneous binding of lithium cations and halide anions by the receptor, according to the invention, a complex is formed that is soluble in the organic phase in a wide range of concentrations. Thanks to this, it is possible to use the receptor in the process of extracting lithium halides from the solid phase to the organic phase, and thus, to isolate lithium halides from samples subjected to extraction, including natural samples and samples subjected to lithium recycling. Due to the selectivity of the binding lithium halides when exposed to halides of heavier alkali metals, it is possible to effectively and efficiently extract lithium halides from samples containing a mixture of alkali metal salts. It should be noted that each receptor will have a slightly different selectivity to specific lithium halides in the presence of halides of heavier alkali metals.

[0057] Method of selective extraction of lithium halides

[0058] The extraction method according to the invention uses the ion pair receptor described above. Extraction is possible due to the formation of a receptor complex after its reversible binding of a lithium halide ion pair, which due to its structure and lipophilic properties, remains soluble in a wide range of concentrations in organic solutions, and at the same time is insoluble in water.

[0059] It is possible to isolate lithium halides from a solid phase into a liquid organic phase, preferably immiscible with water. An organic solvent or a mixture of organic solvents is used in the extraction process. The solvent must be selected so that the receptor complex with the lithium halide ion pair is well soluble in it, otherwise the extraction will not be efficient. When the solid phase (containing the lithium halide) comes into the contact with the organic phase (containing the free receptor), the formation of the receptor complex with the ion pair occurs at the interface, followed by its transfer to the organic phase. The driving force of this process is the affinity of the complex for the nonaqueous phase, as well as its low initial concentration in this phase. Preferably, the organic solvent or mixture of organic solvents is not miscible with water and forms two phases in the contact with an aqueous solution. Then, during the back-extraction, after the complex of the receptor with the lithium halide has dissociated, the free receptor remains in the organic phase. In order to ensure the possibility of conveniently carrying out the extraction in a continuous mode, the water-immiscible organic phase is denser than the aqueous phase. Preferably, the organic solvent or the mixture of water-immiscible organic solvents includes chloroform, dichloromethane, an alkyl ester, an aryl ester, an alkyl ether, an aryl ether, toluene, nitrotoluene or mixtures thereof. Alternatively, the organic solvent or the mixture of organic solvents is mixed with water. Then, the receptor precipitates during the back-extraction. In this embodiment, preferably the organic solvent or the mixture of organic solvents comprises acetonitrile, methanol, ethanol, 2- propanol or any liquid alcohol or derivative thereof, or mixtures of these solvents.

[0060] According to the invention, preferably, the extraction is carried out in a stationary mode, in which the following steps can be distinguished: the actual extraction, the filtration and the back-extraction. Primary extraction is the saturation of the organic receptor solution with the lithium halide present in the solid phase. According to the invention, the solid sample containing the lithium salt is flooded with the organic receptor solution and then shaken or actively mixed for a given period, for example for 24 hours, to saturate the receptor solution. Then, the solution of the receptor complex and the lithium halide ion pair is separated from the solid sample of the lithium salt, for example by decantation or filtration, until a clear, colourless solution of the organic phase is obtained. Next, the back-extraction is carried out into the aqueous phase in order to separate the lithium halide and regenerate the receptor.

[0061] Alternatively, the extraction is carried out in a continuous mode, wherein the solid phase containing the lithium salt is located at the bottom of the vessel / extractor in the constant contact with the organic receptor solution completely covering the solid sample. In turn, the organic solution filling the vessel / extractor is covered from above by an aqueous solution, which is not in the contact with the solid sample of the lithium salt. In this system, the receptor transfers a pair of lithium halide ions from the solid salt phase through the organic phase to the aqueous solution.

[0062] The lithium halide is isolated by the back-extraction of the lithium halide ion pair into the aqueous phase. At the organic and aqueous interface the complex dissociates and the lithium halide passes into the aqueous phase, while the free receptor remains in the organic phase. The solid extraction product containing the lithium halide is obtained after separating the aqueous phase from the organic phase and evaporating water from the aqueous solution obtained in this way or by precipitation in the form of a poorly soluble lithium salt, e.g. lithium carbonate. The extraction from the solid phase is repeated until solid lithium halide of satisfactory purity is obtained.

[0063] Regeneration of the receptor is possible by the back-extraction of the ion pair back into the aqueous phase, which in this case is in excess. The back-extraction is carried out with water devoid of the corresponding ions, preferably pure water, most preferably distilled water or deionized water. In the case of unfavourable coordination of the binding domains of the free receptor with water molecules in the organic phase, methanol is added to the organic solvent, preferably 5% methanol by volume, which by competing for the amide substituents displaces water from the complex with the receptor. In order to isolate the receptor in solid form, the solvent must be evaporated from the organic phase.

[0064] During testing of the receptor according to the invention, in application to the extraction of lithium halides from a solid phase to an organic phase, in the presence of halides of heavier alkali metals, its significant selectivity towards lithium halides has been observed.

[0065] - the efficiency of a single extraction of lithium chloride in the presence of sodium chloride and potassium chloride using receptor I is 38.76% LiCI, 0.84% NaCI and 0.35% KCI relative to the molar concentration of the receptor used,

[0066] - the efficiency of a single extraction of lithium chloride in the presence of sodium chloride and potassium chloride using receptor II is 87.40% LiCI, 3.80% NaCI and 2.60% KCI relative to the molar concentration of the receptor used,

[0067] - the efficiency of a single extraction of lithium chloride in the presence of sodium chloride and potassium chloride using receptor III is 75.93% LiCI, 1.92% NaCI and 0.21% KCI relative to the molar concentration of the receptor used,

[0068] - the efficiency of single extraction of lithium chloride in the presence of sodium chloride and potassium chloride using receptor IV is 62.53% LiCI, 1.96% NaCI and 29.83% KCI relative to the molar concentration of the receptor used.

[0069] Sample experimental data on the selectivity of alkali metal halide binding are presented in the embodiment (Example 7, Table 1). Rubidium and cesium halides have been omitted from the tests due to their marginal occurrence in the natural environment and in lithium-containing battery waste, and also due to the known lack of coordination of rubidium and cesium cations by crown ethers containing less than 6 oxygen atoms in the crown ring. The receptor for selective extraction of lithium halides from a solid phase to a organic phase and the method for selective extraction of lithium halides from a solid phase to a organic phase, using this receptor, have been described in detail below in the embodiments.

[0070] Example 1. The monoamide derivative M was obtained, from which the receptors with the following structures were then obtained I, II, III i IV, and the reference receptor, according to the scheme shown in Fig. 4. Dibutylamine (1.90 ml, 11.2 mmol) was added at the temperature of 0°C to a solution of 4-nitrobenzenesulfonyl chloride (2.25 g, 10.2 mmol) and 2.2 equivalents of triethylamine (2.84 ml) in 10 ml of dry dichloromethane. The reaction mixture was stirred for 20 min and then left overnight at room temperature. After this time, the organic phase was washed with 0.5 M HO (3 x 20 mL) and then the aqueous phase was washed with DCM (20 mL). The organic phases were collected and dried over sodium sulphate. After evaporation of DCM, compound S1 was obtained (3.01 g, 9.16 mmol) as a yellow oil in 90% yield. Then, tin (II) chloride dihydrate (2.25 g, 10 mmol) was added to the solution of compound S1 (660 mg, 2.00 mmol) in 15 ml of dry ethanol and heated for one hour at the temperature of 70°C. After this time, the reaction mixture was poured onto crushed ice and adjusted to pH = 10 with aqueous NaOH. After 30 min, the mixture was extracted with ethyl acetate (3 x 15 mL). The collected organic fractions were dried over sodium sulphate. After evaporation of the solvent, compound S2 was obtained (596 mg) as a red oil, which was used in the next step without further purification. In the final step, 3, 4-dimethoxy-3-cyclobutane-1, 2-dione (284 mg, 2.00 mmol) was added to the solution of amine S2 (596 mg) in 20 mL of methanol and the total was stirred for 1 day at room temperature. After this time, the reaction mixture was concentrated and purified by silica gel column chromatography, wherein the eluent was a methanolxhloroprene mixture (2:98 v / v), to give the final product M as a yellow precipitate (678 mg, 1.24 mmol) in 80% yield.

[0071] Example 2. The receptor of the structural formula I was obtained according to the following procedure. Compound M (350 mg, 0.88 mmol) and triethylamine (185 p, 1.32 mmol) were added to a solution of 4-aminobenzo-9-crown-3 (172 mg, 0.88 mmol) in 30 ml of methanol and stirred for one day at room temperature. Then the reaction mixture was concentrated and purified by silica gel column chromatography (5% methanol in chloroform) to obtain receptor I as a light yellow precipitate (345 mg, 0.62 mmol) in 70% yield.

[0072] The molecular structure of receptor I was confirmed by1H NMR measurements:1H NMR (300 MHz, DMSO-ck) 8: 10.11 (s, 1H), 9.89 (s, 1H), 7.81-7.74 (m, 2H), 7.67-7.61 (m, 2H), 7.19-7.15 (m, 1H), 7.05-6.93 (m, 2H), 4.41-4.35 (m, 2H), 4.25-4.17 (m, 2H), 3.86-3.78 (m, 4H), 3.09-3.01 (m, 4H), 1.53-1.39 (m, 4H), 1.33-1.19 (m, 4H), 0.91-0.81 (m, 6H). The molecular structure of receptor I was confirmed by13C NMR measurements:13C NMR (75 MHz, CDCh) 8: 183.0, 180.8, 166.0, 165.4, 151.4, 148.9, 141.4, 135.0, 133.0, 128.7, 123.8, 119.3, 115.3, 114.6, 74.3, 73.2, 72.4, 72.2, 48.2, 31.0, 19.9, 13.8.

[0073] The molecular structure of receptor I was confirmed by HRMS measurements: calculated molecular peak mass of the CisHssNjOySNa [M+Na]+: 580.2094; peak found: 580.2089.

[0074] Example 3. The receptor of structural formula II was obtained according to the following procedure: Compound M (854 mg, 2.09 mmol) and triethylamine (322 p, 2.30 mmol) were added to a solution of 4-aminobenzo-12-crown-4 (500 mg, 2.09 mmol) in 30 ml of methanol and stirred for one day at room temperature. The reaction mixture was then concentrated and purified by silica gel column chromatography (2% methanol in chloroform) to obtain receptor II as a light yellow precipitate (830 mg, 1.38 mmol) in 69% yield.

[0075] The molecular structure of receptor II was confirmed by1H NMR measurements:1H NMR (300 MHz, DMSO-d6): 10.20 (s, 1 H), 10.00 (s, 1H), 7.82-7.72 (m, 2H), 7.70-7.62 (m, 2H), 7.31-7.25 (m, 1 H), 7.09-7.02 (m, 1H), 6.97-6.89 (s, 1 H), 4.16-4.05 (m, 4H), 3.79-3.59 (m, 8H), 3.10-2.98 (m, 4H), 1.51-1.38 (m, 4H), 1.33-1.18 (m, 4H), 0.92-0.83 (m, 6H).

[0076] The molecular structure of receptor II was confirmed by confirmed by13C NMR measurements:13C NMR (75 MHz, DMSO-d6) 8: 183.0, 181.5, 166.8, 165.0, 151.3, 146.8, 142.9, 133.8, 133.3, 129.0, 119.9, 118.6, 112.6, 109.0, 72.6, 70.9, 70.9, 70.4, 69.4, 69.2, 48.2, 31.0, 19.8, 14.1.

[0077] The molecular structure of receptor II was confirmed by confirmed by HRMS measurements: calculated molecular peak mass of C3oH39N30sSNa [M+Na]+: 624.2350; peak found: 624.2352.

[0078] Example 4. The receptor of structural formula III was obtained according to the following procedure: Compound M (292 mg, 0.74 mmol) and triethylamine (207 p, 1.48 mmol) were added to a solution of 4-aminobenzo-15-crown-5 (209 mg, 0.74 mmol) in 30 ml of methanol and stirred for one day at room temperature. The reaction mixture was then concentrated and purified by silica gel column chromatography (5% methanol in chloroform) to obtain receptor III as a light yellow precipitate (310 mg, 0.48 mmol) in 65% yield.

[0079] The molecular structure of receptor III was confirmed by1H NMR measurements:1H NMR (300 MHz, DMSO-ck) 8: 10.98 (s, 1 H), 10.72 (s, 1 H), 7.78-7.68 (m, 4H), 7.34-7.27 (m, 1 H), 6.97-6.91 (m, 2H), 4.11-3.98 (m, 4H), 3.82-3.71 (m, 4H), 3.67-3.56 (m, 8H), 3.09-2.99 (m, 4H), 1.51-1.37 (m, 4H), 1.33-1.17 (m, 4H), 0.91-0.82 (m, 6H). The molecular structure of receptor III was confirmed by13C NMR measurements:13C NMR (75 MHz, DMSO-ck) 8: 182.8, 180.9, 166.7, 165.1, 149.2, 144.9, 143.1, 133.1, 133.0, 129.0, 118.5, 115.1, 111.1, 105.6, 70.2, 69.6, 69.4, 69.0, 68.8, 68.6, 48.2, 31.0, 19.8, 14.1.

[0080] The molecular structure of receptor III was confirmed by HRMS measurements: calculated molecular peak mass of Cji^jNjC^SNa [M+Na]+: 668.2619; peak found: 668.2621.

[0081] Example 5. The receptor of structural formula IV was obtained according to the following procedure: Compound M (300 mg, 0.76 mmol) and triethylamine (140 p, 1.07 mmol) were added to a solution of 4-aminobenzo-18-crown-6 (248 mg, 0.76 mmol) in 20 ml of methanol and stirred for one day at room temperature. The reaction mixture was than filtered and the collected precipitate was washed several times with methanol. Receptor IV was obtained as a yellow precipitate (372 mg, 0.54 mmol) in 71% yield.

[0082] The molecular structure of receptor IV was confirmed by1H NMR measurements:1H NMR: (300 MHz, DMSO-ck) 8: 10.08 (s, 1H), 9.89 (s, 1H), 7.82-7.71 (m, 2H), 7.69-1.92 (m, 2H), 7.35-7.19 (m, 1H), 7.05-6.70 (m, 2H), 4.21-3.98 (m, 4H), 3.84-3.71 (m, 4H), 3.68-3.46 (m, 12H), 3.14-2.94 (m, 4H), 1.54-1.38 (m, 4H), 1.34-1.16 (m, 4H), 1.02-0.76 (m, 6H).

[0083] The molecular structure of receptor IV was confirmed by13C NMR measurements:13C NMR (75 MHz, DMSO-ck) 8: 182.8, 180.9, 166.7, 165.1, 149.2, 144.9, 143.1, 133.1, 133.0, 129.0, 118.5, 115.1, 111.1, 105.6, 70.2, 69.6, 69.4, 69.0, 68.8, 68.6, 48.2, 31.0, 19.8, 14.1.

[0084] The molecular structure of receptor IV was confirmed by HRMS measurements: calculated molecular peak mass of C34H4?N30ioSNa [M+Na]+: 712.2881; peak found: 712.2879.

[0085] Example 6. A reference receptor was obtained according to the following procedure: Compound M (151 mg, 0.38 mmol) and triethylamine (65 p, 0.76 mmol) were added to a solution of 3,4- dimethoxyaniline (60, 0.38 mmol) in 10 ml of methanol and stirred for one day at room temperature. The reaction mixture was then filtered and the collected precipitate was washed several times with methanol. The reference receptor was obtained as a white precipitate (150 mg, 0.29 mmol) in 77% yield.

[0086] The molecular structure of the reference receptor was confirmed by1H NMR measurements:

[0087] 1H NMR (300 MHz, DMSO-d6): 10.09 (s, 1H), 9.91 (s, 1H), 7.80-7.73 (m, 2H), 7.69-7.61 (m, 2H), 7.32-7.24 (m, 1H), 6.99-6.92 (m, 1H), 6.90-6.84 (m, 1H), 3.79 (s, 3H), 3.74 (s, 3H), 3.09-2.99 (m, 4H), 1.52-1.39 (m, 4H), 1.33-1.19 (m, 4H), 0.92-0.83 (m, 6H).

[0088] The molecular structure of the reference receptor was confirmed by13C NMR measurements:13C NMR (75 MHz, DMSO-d6) 8: 183.2, 181.4, 166.8, 164.8, 149.7, 145.9, 142.9, 133.2, 132.3, 129.0, 118.7, 112.9, 110.9, 104.5, 56.2, 55.9, 48.2, 31.0, 19.8, 14.1.

[0089] The molecular structure of the reference receptor was confirmed by HRMS measurements: calculated molecular peak mass of C26H33N3O&SNa [M+Na]+: 538.1982; found peak: 538.1983.

[0090] Example 7. Quantitative experiments were carried out on the extraction of alkali metal chlorides from a solid phase into chloroform using receptors according to the invention having structures I, II, III, IV and a reference receptor. They consisted in preparing 5 mM solutions of the receptors in chloroform. Then, 2 ml of the prepared solutions were poured over the prepared weighed portions of the appropriate chloride salts in the amount of 10 equivalents each. Then, the prepared systems were mixed for 24 h, after which 1 ml of chloroform solution was taken using a syringe filter and washed several times with deionized water, until 10 ml of aqueous solution was obtained. As a next step, the concentrations of lithium, sodium and potassium cations were determined using high- pressure ion chromatography. Rubidium and cesium chlorides were not included in the tests due to the lack of affinity of the crown ethers used for Rb+and Cs+cations. For each receptor according to the invention, the highest extraction of lithium chloride was observed compared to the extraction of sodium chloride and potassium chloride. The level of extraction using the reference receptor is at the level of background measurements. The partial results obtained for receptors I, II, III, IV and the reference receptor are shown in Figs. 17-21, respectively. The obtained results are summarized in Table 1.

[0091] Table 1. Summary of the results of extraction of alkali metal chlorides from an equimolar solid mixture containing 10 mM LiCI, 10 mM NaCI and 10 mM KCI using receptors I, II, III and IV according to the invention, carried out in accordance with the procedure described in Example 7 using ion chromatography technique. For comparison, the results of measurements using the reference receptor and the results of background measurements devoid of alkali metal halides are presented. Example 8. Titration of receptor II was performed under the control of1H NMR spectroscopy. Receptor II was selected for testing due to its highest selectivity for lithium chloride from a solid phase. It consisted in preparing a solution of compound II in CD3CN at a concentration of 3.13 mM and placing 500 pl of this solution in a test tube. Then, a solution of LiBr salt at a concentration of 26.7 mM was prepared by dissolving LiBr in the previously prepared solution of receptor II.

[0092] An appropriate aliquot of the LiBr salt solution was added one at a time to the test tube, mixed and the1H NMR spectrum was recorded each time. The collected set of spectra is shown in Fig. 22.

[0093] Example 9. Qualitative experiments were carried out on the extraction of alkali metal chlorides from a solid phase to acetonitrile using the receptor of the invention with structure II. Receptor II was selected for the tests due to its highest selectivity for lithium chloride from a solid phase.

[0094] A 5 mM solution of receptor II was prepared in deuterated chloroform. Then, 1 ml aliquots of this solution were poured over weighed amounts of LiCI, NaCI and KCI, respectively, in the amount of 10 molar equivalents each. Then, the solutions prepared in this way were mixed for 24 h, after which 0.5 ml of each was taken using a syringe filter and the1H NMR spectrum was recorded for each sample obtained in this way. Three trial extractions of pure LiCI, NaCI and KCI were carried out, and the extraction process was monitored using1H NMR technique in CD3CN. A downfield shift of the squaramide proton signals was observed, depending on the extracted cation (II: ca. 8.7 ppm; II- LiCI: ca. 11.9 ppm; H-NaCI: ca. 10.9 ppm; ll-KCI: ca. 11.2 ppm). Then, the extraction was carried out from an equimolar mixture of these salts LiCI, NaCI and KCI. It was observed that the obtained1H NMR spectrum is identical to the spectrum of the receptor complex II with lithium chloride, which indicates the selective extraction of LiCI with the omission of NaCI and KCI co-occurring in the extracted sample. The summary of the obtained1H NMR spectra is presented in Figure 23 and Figure 24.

[0095] Example 10. Qualitative experiments were carried out on the extraction of alkali metal chlorides from a solid phase into chloroform using the receptor of the invention with structure II. Receptor II was selected for the tests due to its highest selectivity of lithium chloride from a solid phase.

[0096] A 5 mM solution of receptor II was prepared in deuterated chloroform. Then, 1 ml aliquots of this solution were poured over weighed amounts of LiCI, NaCI and KCI, respectively, in the amount of 10 molar equivalents each. Then, the solutions prepared in this way were mixed for 24 h, after which 0.5 ml of each was taken using a syringe filter and the1H NMR spectrum was recorded for each sample obtained in this way. Three trial extractions of pure LiCI, NaCI and KCI were carried out, ' l. and the extraction process was monitored using1H NMR technique in CDCh. A downfield shift of the squaramide proton signals was observed, depending on the extracted cation (II: ca. 9.0 ppm; II- LiCI: ca. 10.7 ppm; H-NaCI: ca. 10.3 ppm; ll-KCI: ca. 10.2 ppm). Then, extraction was carried out from an equimolar mixture of these salts LiCI, NaCI and KCI. It was observed that the obtained1H NMR spectrum was identical to the spectrum of the receptor complex II with lithium chloride, which indicates the selective extraction of LiCI with the omission of NaCI and KCI co-occurring in the extracted sample. The summary of the obtained1H NMR spectra is presented in Fig. 25 and Fig. 26.

[0097] Example 11. The receptor according to the invention was obtained, containing a central squaramide group, an aryl group (Ar-X) with five -F substituents and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of alkali metal chloride extraction from a solid phase were carried out and the results obtained were similar to those obtained in Examples 8 and 9. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0098] Example 12. The receptor according to the invention was obtained, containing a central squariamide group, an aryl group (Ar-X) with two -CF3 substituents in the meta position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of extraction of alkali metal chlorides from a solid phase were carried out and the results obtained were similar to those obtained in Examples 8 and 9. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0099] Example 13. The receptor according to the invention was obtained, containing a central grouping of a squaramide, an aryl group (Ar-X) with one -NO2 substituent at the para position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of extraction of alkali metal chlorides from a solid phase were carried out and the results obtained were similar to those obtained in Examples 8 and 9. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0100] Example 14. The receptor according to the invention was obtained, containing a central squaramide group, an aryl group (Ar-X) with two -COOBut substituents in the meta position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of extraction of alkali metal chlorides from a solid phase were carried out and the results obtained were similar to those obtained in Examples 8 and 9. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0101] Example 15. The receptor according to the invention was obtained, containing a central squaramide group, an aryl group (Ar-X) with two -CONHexi substituents in the meta position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of alkali metal chloride extraction from a solid phase were carried out and results similar to those obtained in Examples 8 and 9 were obtained. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0102] Example 16. The receptor according to the invention was obtained, containing a central squaramide group, an aryl group (Ar-X) with one -Pent substituent at the para position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of alkali metal chloride extraction from a solid phase were carried out and results similar to those obtained in Examples 8 and 9 were obtained. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

[0103] Example 17. The receptor according to the invention was obtained, containing a central squaramide group, an aryl group (Ar-X) with two -OMe substituents at the meta position and a benzocrown group (Ar-Y) with a 12-crown-4 ether, showing the highest selectivity of lithium cation coordination. Qualitative experiments of alkali metal chloride extraction from a solid phase were carried out and the results obtained were similar to those obtained in Examples 8 and 9. Selective extraction of LiCI was observed, with the omission of NaCI and KCI during extraction from a solid sample containing a mixture of LiCI, NaCI and KCI.

Claims

Claims1. A receptor for selective extraction of lithium halides from a solid phase having a squaramide domain coordinating anions and a crown domain coordinating cations, characterised in that- it has within one molecule a halide anion binding domain and a lithium cation binding domain, forming a structure with the general formula:- the squaramide group is capable of reversibly binding halide anions through their coordination with the protons of the amide groups,- the aryl group with the crown substituent (Ar-Y) is capable of reversibly binding lithium cations through their coordination with the lone electron pairs of the oxygen atoms of the ether group,- the aryl group with the substituent (Ar-X) increases the lipophilicity of the receptor,- the receptor has the ability to selectively extract lithium halides, in the presence of halides of other alcali metals, from a solid to an organic phase, preferably immiscible with water, the receptor is soluble in organic solvents or their mixtures, preferably immiscible with water,- the receptor has the ability to form a complex with a lithium halide ion pair, soluble in organic solvents or mixtures of organic solvents, preferably immiscible with water.

2. The receptor according to claim 1, characterised in that the crown substituent (Y) of the benzocrown group (Ar-Y) is- a 9-crown-3 ether linked to a benzene ring, or- a 12-crown-4 ether linked to a benzene ring, or- a 15-crown-5 ether linked to a benzene ring, or- a 18-crown-6 ether linked to a benzene ring.

3. The receptor according to claim 1, characterised in that the substituted aryl group (Ar- X) has electron-withdrawing properties while retaining a lipophilic character, preferably having substituents (X) such as: -F, -CF3, -NO2, -COOR, -CONR’R” or -SOiNR’R”, preferably - SOiNR’R” or -CONR’R”, wherein R, R' and R" are aliphatic chains with 1-6 carbon atoms, aryl groups or hydrogen.

4. The receptor according to claim 1, characterised in that the aryl group with the substituent (Ar-X) has electron-donating or electron-neutral properties, while retaining a lipophilic character, preferably having substituents (X) such as: -R or -OR, wherein R represents aliphatic chains with 1-6 carbon atoms, aryl groups or hydrogen.

5. The receptor according to claim 1, characterised in that it is soluble in water-immiscible organic solvents, preferably in chloroform, dichloromethane, alkyl esters, aryl esters, alkyl ethers, aryl ethers, toluene and nitrotoluene, or in water-miscible organic solvents, preferably in acetonitrile, methanol, ethanol and 2-propanol, or any liquid alcohol or its derivative, or in mixtures of these solvents.

6. The receptor according to claim 1, characterised in that it is capable of being regenerated by washing it or its solution with water, preferably pure water, preferably distilled water or deionised water, optionally with the addition of methanol, and by subsequent evaporating the solvent.

7. The receptor according to claim 1, characterised in that preferably adopts one of the molecular structures I, II, III or IV:

8. A method of selective extraction of lithium halides from a solid phase into an organic phase, employing a receptor selectively binding lithium cations and halide anions, characterised in that it uses the receptor as described in claims 1-7, preferably the receptor of the structure I, II, III or IV, dissolved in an organic solvent or mixture of organic solvents, being in the contactwith the solid phase from which the extraction is carried out, which receptor reversibly binds the lithium halide ion pair to form a complex soluble in an organic solvent or mixture of organic solvents, wherein the lithium halide is separated by a back-extraction of the lithium halide ion pair into an aqueous phase, which results in the dissociation of the complex and the transfer of the lithium halide to the aqueous phase while the free receptor remains in the organic phase or precipitates therefrom, and the solid extraction product, containing the lithium halide, is obtained after separation an aqueous phase from an organic phase and evaporation of water from the aqueous solution thus obtained or, alternatively, after precipitation of the lithium salt in the aqueous layer in the form of a poorly soluble salt, e.g. lithium carbonate.

9. The method according to claim 8, characterised in that the extraction is carried out in a stationary mode, in which the following can be distinguished:- the actual extraction stage, i.e. saturation of the receptor solution with the lithium halide,- the filtration stage, i.e. separation of the receptor complex solution with the lithium halide from the solid salt,- the back-extraction stage, i.e. dissociation of the receptor complex with the lithium halide as a result of the contact of the organic phase with the aqueous phase.

10. The method according to claim 8, characterised in that the extraction is carried out in a continuous mode, wherein the solid phase at the bottom of the vessel is in constant contact with the receptor solution in a water-immiscible organic solvent, which in turn is covered with an aqueous solution, and the receptor transfers the lithium halide ion pair between the solid salt phase and the aqueous solution.

11. The method according to claim 8, characterised in that the extraction from the solid phase is repeated until a solid lithium halide of satisfactory purity is obtained.12.The method according to claim 8, characterised in that the regeneration of the receptor is carried out by washing with water, preferably with pure water, most preferably with distilled water or deionised water, optionally with the addition of methanol, and then evaporating the solvent.

13. The method according to claim 8, characterised in that the organic solvent or the mixture of organic solvents is not miscible with water and forms two phases upon the contact with an aqueous solution, wherein during the back-extraction of the lithium halide into the aqueous phase the complex of the receptor with the lithium halide ion pair dissociates, wherein the lithium halide passes into the aqueous phase and the receptor remains dissolved in theorganic phase, wherein preferably the organic phase is denser than the aqueous phase, preferably the organic solvent or the mixture of organic solvents comprises chloroform, dichloromethane, an alkyl ester, an aryl ester, an alkyl ether, an aryl ether, toluene or nitrotoluene.14.The method according to claim 8, characterised in that the organic solvent or the mixture of organic solvents is miscible with water, wherein during the back-extraction process of the lithium halide into the aqueous phase, the receptor complex with the lithium halide ion pair dissociates, wherein the lithium halide remains dissolved in the liquid (aqueous-organic) phase and the receptor is precipitated as a precipitate, the organic solvent or mixture of organic solvents preferably comprising acetonitrile, methanol, ethanol or 2-propanol or any liquid alcohol or derivatives thereof.

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