Metal salt extractant, composition, method for recovering metal salts, and method for producing metal salts

Abstract

To provide an extractant for selectively extracting at least one of cuprous salt and silver salt.SOLUTION: The present invention provides a metal salt extractant for extracting at least one of cuprous salt and silver salt. The extractant is a compound represented by general formula (1). In the general formula (1), R1 and R2 each independently represent a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxy group, or a group represented by -NHR', and R' represents a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxy group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] One embodiment of the present invention relates to a metal salt extractant, a composition, a method for recovering a metal salt, and a method for producing a metal salt. [Background technology]

[0002] The automotive industry, information and communication technology industry, and other sectors utilize large amounts of metal resources. However, concerns remain that increasing global demand for metal resources and the uneven distribution of reserves may lead to a reduction in the supply and price increases of these resources. Therefore, attempts are being made to extract and recycle metal resources from industrial waste. Recycling allows for the extraction of individual metal resources with high purity, enabling them to be supplied as products that meet the requirements of various industrial sectors.

[0003] Among metallic resources, transition metals share a common electron configuration in their outermost shell, resulting in similar properties. Therefore, the technology to extract a single transition metal from multiple types of transition metals is complex. When transition metals form metal salts rather than elemental metals, recovering the transition metal in the form of a metal salt allows for the recycling of the recovered metal salt. However, the technology for sorting and recovering metal salts based on their valency is even more complex.

[0004] For example, copper chloride I (CuCl), a chloride salt of monovalent copper ions, is used as a catalyst in organic chemical reactions. Recovering copper chloride I directly after the catalytic reaction can improve recycling efficiency. Silver chloride (AgCl) is also widely used as a photosensitive material in photographic development. Silver chloride can be extracted and recycled from waste liquid after development and used photographs. Furthermore, technologies to remove copper chloride I and silver chloride, which are present as impurities, are expected to improve the purity of products. There is also a need to extract and recycle copper chloride I and silver chloride from various types of industrial waste.

[0005] Among the technologies for extracting metal resources from materials, there is chemical separation, and metal resources can be extracted with high purity using chemical reactions, electrolysis reactions, etc. Among these, the method of separating metals using an extractant in a solvent can perform precise separation of specific metals.

[0006] On the other hand, as a technology for recovering ions from a solvent, there is a method of capturing anions in the solvent using an anion receptor. Depending on the molecular structure of the anion receptor, the ionic species to be captured can be selectively captured. Non-Patent Documents 1 and 2 disclose anion receptors having a urea group at the 8,8'-positions of a 2,2'-binaphthyl group.

Prior Art Documents

Non-Patent Documents

[0007]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] Extractants are being studied for separating cuprous salts and silver salts in a solvent. Since cuprous salts and silver salts themselves are water-insoluble, separation in a non-aqueous solvent is expected. In this case, the separation efficiency can be enhanced by using an extractant that shows solubility in the non-aqueous solvent.

[0009] The anion receptors disclosed in Non-Patent Documents 1 and 2 have a relatively rigid skeleton because their basic structure consists of a 2,2'-binaphthyl group linked to rigid naphthyl groups by single bonds. Furthermore, the urea group introduced at the 8,8'-position is positioned appropriately, enabling them to capture anions. On the other hand, the anion receptors disclosed in Non-Patent Documents 1 and 2 tend to have low solubility in non-aqueous solvents due to their rigid structure resulting from the 2,2'-binaphthyl group.

[0010] One object of the present invention is to provide an extractant that selectively extracts at least one of a cuprous salt and a silver salt. Another object of the present invention is to provide a simple method for extracting, recovering, or producing at least one of a cuprous salt and a silver salt. [Means for solving the problem]

[0011] The gist of this invention is as follows: [1] A metal salt extractant that extracts at least one of a cuprous salt and a silver salt, and is a compound represented by the following general formula (1). [ka] (In general formula (1), R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group.

[0012] [2] The metal salt extractant described in [1], which is a compound represented by the following general formula (2). [ka] (In general formula (2), R 3 and R 4 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group.

[0013] [3] In the above general formula (2), R 3 and R 4 The metal salt extractant according to [2], wherein each is independently an n-butyl group, a tert-butyl group, or a phenyl group. [4] A composition comprising a metal salt extractant and a non-aqueous solvent as described in any of [1] to [3] above. [5] A method for recovering metal salts using a metal salt extractant described in any of [1] to [3] above.

[0014] [6] A method for separating at least one of a cuprous salt and a silver salt from a metal salt-containing material and producing at least one of a cuprous salt and a silver salt, comprising the steps of preparing a mixture containing the metal salt-containing material, a metal salt extractant according to any one of [1] to [3], and a non-aqueous solvent, and A method for producing a metal salt, comprising the step of separating the mixture into solid and liquid phases to obtain a metal salt-containing liquid.

[0015] [7] A method for producing at least one of a cuprous salt and a silver salt by separating at least one of them from a metal salt-containing material, comprising the steps of: preparing a mixture containing the metal salt-containing material, a metal salt extractant described in any of [1] to [3], and a non-aqueous solvent; separating the mixture by solid-liquid separation to obtain a metal salt-containing liquid; and recovering the metal salt extractant from the metal salt-containing liquid. [Effects of the Invention]

[0016] According to one embodiment of the present invention, an extractant can be provided for selectively extracting at least one of a cuprous salt and a silver salt. According to another embodiment of the present invention, a simple method can be provided for extracting, recovering, or producing at least one of a cuprous salt and a silver salt. [Brief explanation of the drawing]

[0017] [Figure 1] Figure 1 is a graph showing the results of measuring the 1H NMR of compound 2b in the presence of a metal salt in the example. [Modes for carrying out the invention]

[0018] One embodiment of the present invention will be described below, but the present invention is not limited by the following examples.

[0019] "Metal salt extractants" A metal salt extractant according to one embodiment is a metal salt extractant that extracts at least one of a cuprous salt and a silver salt, and is characterized by being a compound represented by the following general formula (1).

[0020] [ka]

[0021] (In general formula (1), R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group.

[0022] Hereinafter, compounds represented by general formula (1) will also be collectively referred to as metal salt extractants.

[0023] This metal salt extractant is capable of capturing at least one of cuprous and silver salts in a non-aqueous solvent and can be used to extract at least one of cuprous and silver salts from a non-aqueous solvent. In particular, this metal salt extractant is excellent at selectively capturing chloride ions released into a non-aqueous solvent, and by capturing them together with at least one of their counterions, cuprous and silver ions, it becomes possible to extract them in the form of at least one of copper chloride I (CuCl) and silver chloride (AgCl).

[0024] An anion receptor having a urea group at the 8,8'-positions of a 2,2'-binaphthyl group has an excellent ability to associate and capture anions because it has a rigid structure due to the 2,2'-binaphthyl group and has urea groups at both ends. This compound is represented by the following general formula (10).

[0025] [Chemical formula]

[0026] (In the general formula (10), R is an n-butyl group, a tert-butyl group, or a phenyl group.)

[0027] With respect to the compound represented by the general formula (10), the compound represented by the general formula (1) has a structure in which the binaphthalene skeleton is substituted with a skeleton having an aliphatic chain and a sulfur atom (S). Due to its flexible structure, it is considered to show high solubility in non-aqueous solvents. In the compound represented by the general formula (1), the amide bonds at both ends are predicted to associate with anions, particularly halide ions such as chloride ions. Further, in the general formula (1), R 1 and R 2 are imino groups, and it is predicted that the ability to associate with anions will be further enhanced by introducing urea groups at both ends. On the other hand, due to the flexible structure, the ability to associate with anions tends to decrease. Considering the high solubility in organic solvents, it is possible to efficiently capture anions from an organic solvent by adding these compounds to the organic solvent at a high concentration. Also, since they can be added to a non-aqueous solvent at a high concentration, it is possible to reduce the amount of non-aqueous solvent used in the extraction process.

[0028] The compound represented by general formula (1) has a stronger interaction with the cation when a sulfur atom (S) is introduced. Based on the HSAB rule, the strong interaction between the soft sulfur atom (S) and the soft cuprous or silver ion allows for the selective capture of the cuprous or silver ion. In this way, the cuprous or silver ion and its counter anion are captured within a single molecule, allowing it to function as an extractant for at least one of the cuprous or silver salts. On the other hand, it has low coordinating ability to other harder transition metal ions, resulting in high selectivity.

[0029] In general formula (1), R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', and R' may be a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group. In general formula (1), R 1 and R 2 They may be the same or different from each other.

[0030] R 1 and R 2 The alkyl group introduced may be a linear alkyl group or a branched alkyl group, and may be linear or alicyclic. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. Examples of this alkyl group include linear alkyl groups such as methyl, ethyl, propyl, isopropyl, n-butyl, tert-butyl, sec-butyl, isobutyl, pentyl, hexyl, heptyl, octyl, isooctyl, 2-ethylhexyl, decyl, and dodecyl groups; and alicyclic alkyl groups such as cyclopentyl, cyclohexyl, cycloheptyl, or groups in which at least one hydrogen atom of these is substituted with an alkyl group. Among these, linear alkyl groups are preferred, alkyl groups with 1 to 4 carbon atoms are more preferred, and even more preferably n-butyl or tert-butyl groups.

[0031] R 1 and R 2 The aryl group introduced as such preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms. This aryl group may be monocyclic, polycyclic, or fused, and may have 1 to 4 aromatic rings, or a fused ring of 2 to 4 aromatic rings, and preferably has one benzene ring. Examples of this aryl group include phenyl, naphthyl, anthracenyl, phenantrenyl, tetracerenyl, biphenyl, terphenyl, and fluorenyl groups. Among these, the phenyl group is preferred. These aryl groups may have at least one hydrogen atom substituted with an alkyl group, for example, a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms, specifically, p-tolyl, m-tolyl, and o-tolyl groups.

[0032] R 1 and R 2 The heteroaryl group introduced is a group having a carbon atom and a heteroatom on a ring, and examples of heteroatoms include nitrogen, oxygen, sulfur, silicon, boron, and phosphorus atoms. The total number of atoms of carbon and heteroatoms in this heteroaryl group is preferably 5 to 24, more preferably 6 to 12, and even more preferably 6 to 8. Examples of this heteroaryl group include groups having a 6-membered heteroaromatic ring such as pyridine and pyrazine, groups having a condensed heteroaromatic ring such as quinoline, isoquinoline, acridine, and phenanthroline, and groups having a 5-membered heteroaromatic ring such as furan, pyrrole, and thiophene.

[0033] R 1 and R 2The alkoxy group introduced may have a linear or branched alkyl group as the alkyl group portion, and may be linear or alicyclic. The alkoxy group preferably has 1 to 20 carbon atoms, more preferably 1 to 8 carbon atoms, and even more preferably 1 to 4 carbon atoms. The alkoxy group is represented, for example, as -O-R', where R' represents an alkyl group, specifically as described above for alkyl groups. More preferably, alkoxy groups having 1 to 4 carbon atoms include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, tert-butoxy, sec-butoxy, and isobutoxy groups.

[0034] R 1 and R 2 In the group represented by -NHR' which is introduced as, R' is the R described above. 1 and R 2 The functional groups described above are examples.

[0035] Preferably, R 1 and R 2 Each of these is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 24 carbon atoms, a heteroaryl group having 5 to 24 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, or a group represented by -NHR'. Here, R' is preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 24 carbon atoms, a heteroaryl group having 5 to 24 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or a hydroxyl group. More preferably R 1 and R 2Each of these is independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, a hydroxyl group, or a group represented by -NHR', and among these, an alkyl group having 1 to 8 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, or a group represented by -NHR' is preferred. Here, R' is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group having 6 to 12 carbon atoms, a heteroaryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or a hydroxyl group, and more preferably an alkyl group having 1 to 8 carbon atoms or a heteroaryl group having 6 to 12 carbon atoms. In a preferred example, R 1 and R 2 Each of these is independently an alkyl group having 1 to 4 carbon atoms, an aryl group having 6 to 8 carbon atoms, or a group represented by -NHR' (where R' is an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 8 carbon atoms), and more preferably an n-butyl group, a tert-butyl group, a phenyl group, or a group represented by -NHR (where R' is an n-butyl group, a tert-butyl group, or a phenyl group). In a more preferred example, R 1 and R 2 At least one of them is a tert-butyl group or -NHR' (where R' is a tert-butyl group), and more preferably R 1 and R 2 Both are tert-butyl groups or -NHR' (where R' is a tert-butyl group).

[0036] An example of a compound represented by general formula (1) is R 1 and R 2 Examples include compounds in which the group is represented by -NHR'. Specifically, these are compounds represented by the following general formula (2). In general formula (2), R 3 and R 4 Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group. For details on each functional group, see above R 1 and R 2The things explained above can be listed.

[0037] [ka]

[0038] In general formula (2), R 3 and R 4 Each of these is preferably an alkyl group, and the number of carbon atoms in the alkyl group is preferably 1 to 20, more preferably 1 to 10, even more preferably 1 to 8, and even more preferably 1 to 4. 3 and R 4 Each of these groups, independently, preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms, and even more preferably 6 to 8 carbon atoms, if it is an aryl group. Specifically, R 3 and R 4 Each of these groups is independently preferably an n-butyl group, a tert-butyl group, or a phenyl group, with the tert-butyl group being preferred.

[0039] Specific compounds are listed below. In the structural formulas below, n-Bu represents an n-butyl group, t-Bu represents a tert-butyl group, and Ph represents a phenyl group.

[0040] [ka]

[0041] Among the compounds described above, compound 2b is preferred from the viewpoint of solubility. The compounds described above may be provided as individual compounds or as mixtures.

[0042] "Methods for synthesizing compounds" The following describes a method for synthesizing the compound represented by general formula (1). Note that the compound in one embodiment is not limited to the compound synthesized by the following synthesis method. Because the compound represented by general formula (1) has a relatively simple molecular structure, the synthesis procedure is also simple, and it can be synthesized in a single reaction from commonly used starting compounds.

[0043] One example of a method for synthesizing a compound represented by general formula (1) may involve introducing an isocyanate derivative, a carboxylic acid halide, or the like into a compound represented by general formula (3) below.

[0044] [ka]

[0045] More specifically, one example of a method for synthesizing the compound represented by general formula (2) may involve introducing isocyanic acid derivatives to the amino groups at both ends of 1,2-bis(2-aminoethylthio)ethane.

[0046] The isocyanate derivative is a compound represented by R''NCO. R'' is R in general formula (2). 3 and R 4 These are groups introduced as such, and the details are as described above. Specifically, examples of isocyanate derivatives include alkyl isocyanates and aryl isocyanates. Examples of alkyl isocyanates include methyl isocyanate, ethyl isocyanate, propyl isocyanate, isopropyl isocyanate, n-butyl isocyanate, sec-butyl isocyanate, tert-butyl isocyanate, isobutyl isocyanate, pentyl isocyanate, hexyl isocyanate, and cyclohexyl isocyanate. Examples of aryl isocyanates include phenyl isocyanate.

[0047] This reaction can be carried out in various solvents. Suitable solvents include, for example, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; alcohol solvents such as methanol, ethanol, isopropanol, ethylene glycol, and diethylene glycol; ether solvents such as diethyl ether, diethylene glycol dimethyl ether, and tetrahydrofuran; amide solvents such as N,N-dimethylformamide and N,N-dimethylacetamide; ester solvents such as ethyl acetate and γ-butyrolactone; and water. Non-aqueous solvents used in the compositions described later may also be used as solvents. After the reaction, the solvent and other components may be removed from the reaction mixture as needed, and the product can be obtained by filtration and drying. Alternatively, the product may be isolated using chromatography for further purification.

[0048] 1,2-Bis(2-aminoethylthio)ethane can be synthesized by conventional methods, and commercially available products may also be used, for example.

[0049] "composition" According to one embodiment, a composition comprising a metal salt extractant and a non-aqueous solvent can be provided. As the metal salt extractant, the metal salt extractant according to the above embodiment can be used. This composition can be used for the extraction of at least one of a cuprous salt and a silver salt. For example, by mixing this composition with a metal salt-containing material containing at least one of a cuprous salt and a silver salt, the metal salt extractant can selectively capture at least one of the cuprous salt and the silver salt from the metal salt-containing material, and at least one of the cuprous salt and the silver salt can be dissolved in the non-aqueous solvent.

[0050] Various types of cuprous and silver salts can be used as the extraction targets, regardless of their solubility in non-aqueous solvents. Examples of cuprous salts include copper I halides such as copper I chloride (CuCl), CuBr, and CuI, and copper I acetate. Examples of silver salts include silver halides such as silver chloride (AgCl), AgBr, and AgI, and silver nitrate. A particularly significant feature is the ability to dissolve silver chloride, which generally has extremely low solubility in solvents. Cuprous and silver salts may be used individually or in combination of two or more.

[0051] Various non-aqueous solvents can be used without particular limitations. Examples of non-aqueous solvents include: cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate; linear carbonates such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, butyl ethyl carbonate, and dipropyl carbonate; cyclic carboxylic acid esters such as γ-butyrolactone; compounds having a nitrile group such as acetonitrile; linear ethers such as 1,2-dimethoxyethane and dimethoxymethane; tetrahydrofuran, 1,3-dioxolane, and 1,4-dioxy Ether compounds such as cyclic ethers like san, 1,3-dioxane, and 2-methyltetrahydrofuran; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; linear carboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, and ethyl propionate; compounds having a sulfonyl group such as sulfolane, propanesultone, 3-methylsulfolane, and 2,4-dimethylsulfolane; phosphate esters such as trimethyl phosphate and triethyl phosphate; and methylene chloride, cyclopentanone, cyclohexylbenzene, 3-methyl-1,3-oxazolidine-2-one, and dimethyl sulfoxide.

[0052] The non-aqueous solvent may be a compound having substituents such as fluorine atoms or chlorine atoms, or the non-aqueous solvent may be a compound in which fluorine atoms or chlorine atoms have been substituted. For example, it may be a compound having one or more fluorine atoms or chlorine atoms in a cyclic carbonate, linear carbonate, ether compound, or linear carboxylic acid ester. Specifically, examples include fluoroethylene carbonate and chloroethylene carbonate. Chloroform is another example.

[0053] The non-aqueous solvents described above may be used individually or in combination of two or more. When using two or more non-aqueous solvents in combination, it is preferable to use a combination that forms a single phase in the composition.

[0054] The composition may be a non-aqueous composition, for example, one in which the water content is limited to 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less relative to the total amount of the composition, and may be substantially water-free. A lower water content allows for more stable maintenance of the metal salt extractant in the composition.

[0055] In the composition of one embodiment, the metal salt extractant is preferably present in a molar ratio of 0.01 or more, more preferably 0.05 or more, and even more preferably 0.1 or more, per 1 unit of non-aqueous solvent. In the composition of one embodiment, the metal salt extractant is preferably present in a molar ratio of 1 or more, more preferably 5 or more, and even more preferably 10 or more, per 1 unit of salt.

[0056] The compound represented by general formula (1) has a structure that can capture one cuprous or silver ion and a counterion per molecule. Therefore, it is possible to recover metal salts within the range of one cuprous or silver ion per molecule of the compound represented by general formula (1), and the amount of metal salt extractant to be used should be determined according to the predicted amount of metal salt recovered.

[0057] Furthermore, the composition according to one embodiment may be a composition that is liquid at 30°C, and more preferably a composition that is liquid at 25°C. The composition according to one embodiment may also have reduced fluidity at lower temperatures, becoming gel-like or solid.

[0058] The composition of one embodiment can be used, for example, in a method for recovering at least one of a cuprous salt and a silver salt from a metal salt-containing material and producing at least one of a cuprous salt and a silver salt. In other examples, the composition of one embodiment can be used in a method for recovering at least one of a cuprous salt and a silver salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method for adsorbing at least one of a cuprous salt and a silver salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method for adsorbing and removing at least one of a cuprous salt and a silver salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method for purifying at least one of a cuprous salt and a silver salt from a metal salt-containing material. In yet another example, the composition of one embodiment can be used in a method for purifying at least one of a cuprous salt and a silver salt from a metal salt-containing material to produce a high-concentration metal salt composition.

[0059] "Method for producing metal salts" According to one embodiment, a method for producing at least one of a cuprous salt and a silver salt by separating them from a metal salt-containing material is provided, comprising the steps of: preparing a mixture containing a metal salt-containing material, a metal salt extractant according to any one of claims 1 to 3, and a non-aqueous solvent; and separating the mixture into solid and liquid phases to obtain a metal salt-containing liquid. The metal salt extractant can be the metal salt extractant according to the above embodiment.

[0060] The metal salt-containing material is not particularly limited as long as it may contain at least one of a cuprous salt and a silver salt. If the metal salt-containing material is solid, it is preferable that it be in powder, crushed, or granular form from the viewpoint of efficiency of dissolution or dispersion. The metal salt-containing material may be minerals or industrial waste. In this case, the minerals or industrial waste may be decomposed, dismantled, crushed, etc., and then physically separated according to shape, magnetic force, electrical properties, specific gravity, etc., to prepare the metal salt-containing material. The metal salt-containing material may also be waste liquid after a chemical reaction such as a catalytic reaction, industrial waste liquid, etc.

[0061] The metal salt-containing material is preferably water-free. For example, the water content may be limited to 1% by mass or less, 0.5% by mass or less, or 0.1% by mass or less relative to the total amount of the metal salt-containing material, and may be substantially water-free. If the metal salt-containing material contains water, the stability of the metal salt extractant may be impaired during the extraction process. The metal salt-containing material may be prepared in a dissolved or dispersed state in a non-aqueous solvent, and may be mixed with the metal salt extractant and the non-aqueous solvent in this state. The non-aqueous solvent used here may be one of those described in the section on non-aqueous solvents included in the above composition.

[0062] The cuprous salts and silver salts that may be included in the metal salt-containing material may be one or more of those described above, or in combination of two or more. The metal salt-containing material may contain only one or both of the cuprous salts and silver salts as metal salts, or it may contain impurities in addition to one or both of the cuprous salts and silver salts, or it may contain other metal salts in addition to one or both of the cuprous salts and silver salts. Other metal salts are not particularly limited, but examples include salts of divalent transition metals, salts of trivalent transition metals, salts of tetravalent or higher polyvalent transition metals, salts of alkali metals, salts of alkaline earth metals, etc. Specifically, examples include manganese-II chloride (MnCl2), iron-II chloride (FeCl2), cobalt-II chloride (CoCl2), nickel-II chloride (NiCl2), copper-II chloride (CuCl2), zinc chloride (ZnCl2), sodium chloride, potassium chloride, magnesium chloride, calcium chloride, etc. These may be included one or more of them in combination of two or more.

[0063] For example, a metal salt extractant according to one embodiment can selectively capture and extract salts of monovalent transition metals, such as at least one of cuprous salts and silver salts, and is therefore useful for selectively recovering at least one of cuprous salts and silver salts from salts of divalent or higher transition metals, particularly salts of divalent transition metals.

[0064] The content of cuprous salts and silver salts in the metal salt-containing material is not particularly limited, and both can be recovered whether they are present in trace or large amounts. For example, the total amount of cuprous salts and silver salts is preferably 0.1 to 100% by mass, and more preferably 40 to 80% by mass, relative to the total amount of the metal salt-containing material.

[0065] Next, the process of preparing a mixture containing a metal salt-containing material, a metal salt extractant, and a non-aqueous solvent will be described. The method of mixing these components is not particularly limited; they can be added to a container all at once or in portions and mixed using a stirrer or the like. Alternatively, a composition containing a metal salt extractant and a non-aqueous solvent may be prepared in advance, and the metal salt-containing material may be added to this composition all at once or in portions and mixed. The reactivity of the mixture can be increased by heating it. The heating temperature is preferably 30 to 100°C, more preferably 50 to 100°C, and even more preferably 80 to 100°C. The heating time can be set appropriately depending on the scale of the reaction system, the heating temperature, the type and shape of the materials, etc., and may be, for example, 10 minutes to 5 hours, or 1 to 2 hours. Heating may be carried out continuously or intermittently from the preparation of the mixture to the solid-liquid separation of the mixture.

[0066] In the mixture, the metal salt extractant is preferably at a molar concentration of 0.01 to 5 M, and more preferably at 0.5 to 1.0 M. In the mixture, the amount of metal salt-containing material varies depending on the assumed amounts of cuprous salt and silver salt contained therein, but for example, it is preferably at 0.1 to 100% by mass, and more preferably at 40 to 100% by mass, relative to the total amount of the mixture.

[0067] Next, the process of obtaining a metal salt-containing liquid by solid-liquid separation of the mixture will be described. Solid-liquid separation can be carried out by methods such as filtration, centrifugation, and sedimentation. In the filtration method, filter paper, filter cloth, membrane filters, etc., can be used. The resulting metal salt-containing liquid may contain a non-aqueous solvent, a metal salt extractant, and cuprous and silver salts. If the metal salt-containing material contains other components besides cuprous and silver salts, and these other components are not soluble in the non-aqueous solvent, these other components can be removed as solids by solid-liquid separation.

[0068] A step of recovering the metal salt extractant from the metal salt-containing solution may be included after the step of obtaining the metal salt-containing solution. For example, as a method of recovering the metal salt extractant from the metal salt-containing solution, water may be added to the metal salt-containing solution, the metal salt extractant may be extracted into an organic solvent, and the insoluble salt may be recovered by filtration or other means.

[0069] The following describes a specific procedure for extracting metal salts. (Step 1) Sample: Sample 1 containing CuCl, MnCl2, and ZnCl2. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0070] Sample 1, a metal salt extractant, and a non-aqueous solvent are mixed to obtain a mixture. The mixture is stirred and / or heated to partially dissolve the solids in the mixture. The mixture is separated into solid and liquid components to remove the solids and obtain a metal salt-containing solution. At this time, the compound represented by general formula (1) selectively captures CuCl, causing CuCl to dissolve in the non-aqueous solvent. As a result, MnCl2 and ZnCl2 are recovered in the solids, and CuCl is recovered in the metal salt-containing solution. When AgCl is used instead of CuCl, AgCl is also recovered in the metal salt-containing solution.

[0071] (Step 2) Sample: CuCl, NiCl2, and Sample 2 containing CuCl2. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0072] Step 2 is the same as Step 1 except that the sample is changed. In this case, the compound represented by general formula (1) selectively captures CuCl and dissolves CuCl in the non-aqueous solvent, so NiCl2 and CuCl2 are recovered in the solids and CuCl is recovered in the metal salt-containing solution. When AgCl is used instead of CuCl, AgCl is also recovered in the metal salt-containing solution. NiCl2 and CuCl2 show some solubility in CHCl3 in the presence of a metal salt extractant, but their solubility is lower than that of CuCl and AgCl, so CuCl and AgCl are preferentially recovered. It is also possible to prevent the contamination of the recovered metal salt-containing solution with CuCl2 by washing sample 2 beforehand with a solvent that can dissolve CuCl2 but does not easily dissolve CuCl and AgCl. Examples of such washing solvents include acetonitrile.

[0073] (Step 3) Sample: Sample 3 containing CuCl and FeCl2. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0074] Step 3 is the same as Step 1 except that the sample is changed. In this case, the compound represented by general formula (1) selectively captures CuCl and dissolves CuCl in the non-aqueous solvent, so FeCl2 is recovered in the solids and CuCl is recovered in the metal salt-containing solution. When AgCl is used instead of CuCl, AgCl is also recovered in the metal salt-containing solution. FeCl2 shows some solubility in CHCl3 in the presence of a metal salt extractant, but its solubility is lower than that of CuCl and AgCl, so CuCl and AgCl are preferentially recovered. In addition, FeCl2 shows solubility in CHCl3 in the absence of a metal salt extractant, but CuCl and AgCl are not easily soluble in CHCl3, so it is possible to prevent contamination of the recovered metal salt-containing solution with FeCl2 by washing sample 3 with CHCl3 beforehand. Furthermore, by pre-washing sample 3 with a solvent that can dissolve FeCl2 or CoCl2 but does not readily dissolve CuCl and AgCl, it is possible to prevent contamination of the recovered metal salt-containing solution with FeCl2 or CoCl2. Examples of such washing solvents include acetonitrile and water.

[0075] (Step 4) Sample: Sample 4 containing CuCl and CoCl2. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: CHCl3.

[0076] Step 4 is the same as Step 1 except that the sample is changed. In this case, the compound represented by general formula (1) selectively captures CuCl and dissolves CuCl in the non-aqueous solvent, so CoCl2 is recovered in the solids and CuCl is recovered in the metal salt-containing solution. When AgCl is used instead of CuCl, AgCl is also recovered in the metal salt-containing solution. CoCl2 shows some solubility in CHCl3 in the presence of a metal salt extractant, but its solubility is lower than that of CuCl and AgCl, so CuCl and AgCl are preferentially recovered. In addition, CoCl2 shows solubility in CHCl3 in the absence of a metal salt extractant, but CuCl and AgCl are not easily soluble in CHCl3, so it is possible to prevent contamination of the recovered metal salt-containing solution with CoCl2 by washing sample 4 with CHCl3 beforehand. Since CoCl2 is soluble in acetonitrile, acetonitrile can also be used as a washing solvent.

[0077] (Step 5) Sample 5 contains CuCl, MnCl2, FeCl2, CoCl2, NiCl2, CuCl2, and ZnCl2. Metal salt extractants: Compounds represented by general formula (1). Non-aqueous solvent: MeCN (acetonitrile).

[0078] In step 5, sample 5 is first washed with CHCl3 to remove FeCl2 and CoCl2. After washing with CHCl3, sample 5 is washed with MeCN to remove any remaining CoCl2 and CuCl2. The subsequent steps are the same as in step 1, except that sample 5 after washing with MeCN is used. At this time, the compound represented by general formula (1) selectively captures CuCl, and CuCl dissolves in the non-aqueous solvent, so MnCl2, NiCl2, and ZnCl2 are recovered in the solids, and CuCl is recovered in the metal salt-containing solution. A similar trend is observed when AgCl is used instead of CuCl, and AgCl is recovered in the metal salt-containing solution. However, since AgCl is less soluble than CuCl in MeCN in the presence of a metal salt extractant, AgCl cannot be extracted alone, and NiCl2, etc., may be mixed in. Therefore, to extract AgCl with greater accuracy, it is better to use CHCl3 as in steps 1 to 4. [Examples]

[0079] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following description, t-Bu represents a tert-butyl group and Ph represents a phenyl group.

[0080] "Examples of metal salt extraction tests" (Synthesis method for compound 4b) The following compound 4b was synthesized. [ka]

[0081] (Synthesis method) A solution of 500 mg of 1,2-bis(2-aminoethoxy)ethane (obtained from Tokyo Chemical Industry Co., Ltd.) and tert-butyl isocyanate (735 mg) in tetrahydrofuran (6 mL) was refluxed under an argon atmosphere for 18 hours. The solution was cooled, and the resulting colorless solid was filtered by suction to obtain compound 4b (804 mg, 69%) represented by (4b) above. Mp 151~156°C.

[0082] 1H NMR (500 MHz, CDCl3) δ 5.46 (s, 2H), 5.15 (s, 2H), 3.75 (s, 4H), 3.56 (t,4H, J = 4.6 Hz), 3.31 (q, 4H, J = 4.6 Hz), 1.33 (s, 18H). 13 C NMR (126 MHz, CDCl3) δ158.2, 70.8, 70.2, 50.1, 40.0, 29.5.

[0083] (Synthesis method for compound 2b) The following compound 2b was synthesized. [ka]

[0084] (Synthesis method) Under an argon atmosphere, tert-butyl isocyanate (0.65 mL, 5.51 mmol, 2.0 eq) was added in small amounts by syringe to a 10 mL solution of 1,2-bis(2-aminothio)ethane (499 mg, 2.77 mmol) in THF (10 mL) at room temperature. The reaction mixture was stirred at room temperature for 3 hours, cooled, and then evaporated under reduced pressure. The residue was recrystallized from THF to obtain the product as a colorless solid. Yield: 470 mg, 45%. Mp: 161.0~162.1°C.

[0085] 1 H NMR (500 MHz, CDCl3) δ 5.13 (t, 2H, J = 5.5 Hz), 4.73 (s, 2H), 3.35 (dt, 2H, J1= 6.6, J2= 5.5 Hz), 3.78 (s, 4H), 2.69 (t, 4H, J = 6.6 Hz), 1.33 (s, 18). 13 C NMR (126 MHz, CDCl3) δ 157.6, 50.3, 40.0, 32.6, 32.1, 29.6.

[0086] (Evaluation of the solubility of metal salts 1) Table 1 shows the evaluation results for combinations of solvent, host, and guest, and the dissolution of the guest metal salt. According to the combinations shown in Table 1, equimolar amounts of the host compound and guest compound were added to a composition of CHCl3 (chloroform), a solvent containing 0.05 M of the host compound 4b or 2b. The mixture was then heated and stirred at 70°C for 0.5 hours. After cooling to room temperature (25°C), the dissolution of the mixture was visually observed within 30 minutes. "None" in Table 1 represents the case where no host compound was added; the mixture was prepared using the same procedure except for the absence of a host compound, and the dissolution was observed. Solubility was evaluated based on the following criteria. The results are shown in the table. +++: Dissolves to about 0.05M ++: Dissolves to about 0.01M +: Indicates coloration derived from salt. -: Does not dissolve and does not show coloration.

[0087] [Table 1]

[0088] The results shown in the table indicate that compound 2b selectively captures and extracts CuCl and AgCl. Since NiCl2 and CuCl2 have lower solubility than CuCl and AgCl in the presence of compound 2b, it is considered that CuCl and AgCl are preferentially captured and extracted by compound 2b even in the presence of NiCl2 and CuCl2. Similarly, since AgCl has lower solubility than CuCl in the presence of compound 2b, it is considered that CuCl is preferentially captured and extracted by compound 2b even in the presence of AgCl. CuCl is not captured by compound 4b, but is selectively captured by compound 2b. For example, if CuCl and AgCl are simultaneously captured by compound 2b, then CuCl and AgCl can be separated by compound 4b before and after the extraction process using compound 2b. Although not shown in the table, preliminary studies showed that FeCl2 and CoCl2 are soluble in CHCl3 even without the addition of an extractant, so evaluation with an extractant was omitted.

[0089] (Evaluation of the solubility of metal salts, part 2) Table 2 shows the evaluation results for combinations of solvent, host, and guest, and the dissolution of the guest metal salt. According to the combinations shown in Table 2, a 0.05 M composition of MeCN (acetonitrile), a solvent containing either host compound 4b or 2b, was prepared by adding an equimolar amount of guest compound to the host. The mixture was then heated and stirred at 90°C for 0.5 hours. After cooling to room temperature (25°C), the dissolution of the mixture was visually observed within 30 minutes. In Table 1, "none" indicates the case where no host compound was added; the mixture was prepared using the same procedure except for the absence of a host compound, and the dissolution was observed. Based on the observations, solubility was evaluated according to the following criteria. The results are shown in the table. +++: Dissolves to about 0.05M ++: Dissolves to about 0.01M +: Indicates coloration derived from salt. -: Does not dissolve and does not show coloration.

[0090] [Table 2]

[0091] The results shown in the table indicate that compound 2b selectively captures and extracts CuCl and AgCl. Since CuCl is more soluble than AgCl in the presence of compound 2b, it can be seen that CuCl is preferentially captured by compound 2b and can be extracted. CuCl is not captured by compound 4b, but is selectively captured by compound 2b. For example, if CuCl and AgCl are simultaneously captured by compound 2b, then CuCl and AgCl can be separated by compound 4b before and after the extraction process using compound 2b.

[0092] "Evaluation of meeting size" Compounds 4b and 2b were synthesized and prepared as described above.

[0093] (Method of synthesizing compound 4c) The following compound 4c was synthesized. [ka]

[0094] (Synthesis method) A solution of 1,2-bis(2-aminoethoxy)ethane (obtained from Tokyo Chemical Industry Co., Ltd.) and phenyl isocyanate (1.77 g) in tetrahydrofuran (10 mL) was refluxed under an argon atmosphere for 1 hour. The solution was cooled, evaporated under reduced pressure, and the residue was recrystallized from ethyl acetate to obtain compound 4c (2.51 g, 95%) as a colorless solid. Mp 130.0~130.5°C.

[0095] 1 H NMR (500 MHz, CDCl3) δ 7.62 (s, 2H), 7.34 (dd, 4H, J1 = 8.6, J2 = 1.2 Hz), 7.24 (dd, 4H, J1 = 8.6, J2 = 7.2 Hz), 7.00 (t, 2H, J = 7.2 Hz), 5.53 (t, 2H, J = 5.2 Hz), 3.65 (s, 4H), 3.60 (t, 4H, J = 5.2 Hz), 3.40 (q, 4H, J = 5.2 Hz).

[0096] (Synthesis method for compound 2c) The following compound 2c was synthesized. [ka]

[0097] (Synthesis method) Under an argon atmosphere, phenyl isocyanate (0.60 mL, 5.55 mmol, 2.0 eq) was added in small amounts by syringe to a solution of 1,2-bis(2-aminothio)ethane (503 mg, 2.79 mmol) in THF (10 mL) at room temperature. The reaction mixture was stirred under reflux for 3 hours, cooled, and then evaporated under reduced pressure. The residue was recrystallized from THF to obtain the product as a colorless solid. Yield: 397 mg, 35%. Mp: 181.1~194.9°C.

[0098] 1 H NMR (500 MHz, DMSO-d6): d 2.64 (t, 4H, J = 6.86 Hz), 2.75 (s, 4H), 3.26 (dt, 4H, J1= 6.86, J2= 5.82 Hz), 6.28 (t, 2H, J = 5.82 Hz),6.88 (tt, 2H, J1=7.50, J2=1.00 Hz), 7.20 (dt, 4H, J1= 6.88, J2= 1.83 Hz), 7.37 (dd, 4H, J1= 8.52, J2= 1.22 Hz), 8.58 (s, 2H).

[0099] (Evaluation of meeting volume) Table 3 shows the results of evaluating the association constants for various anion and extractant combinations. (5.0 × 10⁶ in a 5 mL volumetric flask) -3 Prepare a CD3CN solution containing M 2b or 4b, and use this solution to measure 5.0 × 10 in a 2 mL volumetric flask. -2 A solution containing M TBAAcO (tetrabutylammonium acetate) or TBACl (tetrabutylammonium chloride) was prepared. 500 μL of the 2b or 4b solution was added to the NMR tube using a microsyringe, and the solution was analyzed in the absence of anions. 1 1H NMR was measured. Then, the guest solution prepared using a microsyringe was added in equivalent volume. 1The procedure for measuring 1H NMR was repeated several times. Based on the measured data, the association constant was determined by performing curve fitting using the nonlinear least squares method. The reproducibility of the results was confirmed by repeating the measurement three times, and the average value was calculated. The results are shown in Table 3.

[0100] [Table 3]

[0101] As shown in the table, compounds 4b and 4c and compounds 2b and 2c all contain chloride ions (Cl - ) and acetate ions (AcO - It can be seen that they associate with ). From this, it can be inferred that compounds 4b, 4c and compounds 2b, 2c are capable of capturing the cuprous or silver salts of various anions. On the other hand, as shown in the "Evaluation of Metal Salt Extraction" above, compound 4b and compound 2b have different capture capabilities for cuprous and silver salts. By utilizing this point, selective extraction of cuprous and silver salts becomes possible.

[0102] "Evaluation of solubility in solvents" Compounds 4b and 2b were synthesized and prepared as described above.

[0103] (Evaluation of solubility) Table 4 shows the combinations of solvents and extractants, and the results of solubility evaluation. Each receptor was added to the measurement solvent while heating, allowed to cool, and saturated solutions were obtained by centrifugation and filtration. 500 μL of the saturated solution was added to an NMR tube using a microsyringe and evaporated. After drying under reduced pressure, 100 μL of a 2 mM naphthalene-containing CDCl3 solution and 400 μL of CDCl3 were added. 1 1H NMR was measured. In 2a and 2c, 100 μL of a DMSO-d6 solution containing 4 mM naphthalene, prepared in a 5 mL round-bottom flask, was added to 400 μL of DMSO-d6. 1 1H NMR was measured. Based on the measurement results, solubility was calculated from the ratio of the integral values. The results are shown in Table 4.

[0104] [Table 4]

[0105] As shown in the table, compound 2b is soluble in various solvents. From the results of the "Evaluation of Metal Salt Extraction" above, it can be seen that compound 2b captures CuCl and AgCl in CHCl3 and MeCN. Considering this point, it is thought that any solvent that dissolves compound 2b to the same extent as CHCl3 and MeCN can be used as a solvent when extracting CuCl and AgCl using compound 2b.

[0106] "Compound 2b in the presence of a metal salt" 1 H NMR Compound 2b was synthesized and prepared as described above. In a sample tube, the metal salt and host were added so that the metal salt was 1 equivalent relative to the host. 2 mL of CDCl3 was then added to prepare a solution where both the metal salt and host were 0.05 M. The solution was heated with a hot stirrer until the solvent was gently boiling, and after standing overnight or longer, it was filtered through a membrane filter and then transferred to an NMR tube. 1 1H NMR was measured. The results are shown in Figure 1.

[0107] The results shown in Figure 1 indicate that compound 2b selectively captures CuCl or AgCl, as evidenced by the shift in its peaks (indicated as 1-d in the figure) in the presence of CuCl or AgCl. In contrast, the peaks of compound 2b do not shift in the presence of LiCl, PdCl2, or ZnCl2, indicating that compound 2b does not capture these metal salts. [Industrial applicability]

[0108] Metal salt extractants according to several embodiments of the present invention can be used to extract at least one of cuprous salts and silver salts from various materials. For example, it is possible to extract at least one of cuprous salts and silver salts from industrial waste, industrial wastewater, wastewater after chemical reactions, etc. In particular, it is possible to selectively extract at least one of cuprous salts and silver salts from various transition metal salts. Specifically, it can be used to extract at least one of cuprous salts and silver salts from waste or wastewater during the manufacturing process of battery materials, semiconductor materials, substrate materials, etc., used waste or wastewater therefrom, wastewater from catalytic reactions, wastewater from photographic development, waste from used photographic substrates, etc. By extracting at least one of cuprous salts and silver salts using this metal salt extractant or a composition containing the same, it is possible to recover, produce, adsorb, remove, or purify at least one of cuprous salts and silver salts.

Claims

1. A metal salt extractant that extracts at least one of a cuprous salt and a silver salt, and is a compound represented by the following general formula (1). 【Chemistry 1】 (In general formula (1), R １ and R ２ Each of these groups is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, a hydroxyl group, or a group represented by -NHR', where R' is a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group.

2. The metal salt extractant according to claim 1, wherein the compound is represented by the following general formula (2). 【Chemistry 2】 (In general formula (2), R ３ and R ４ Each of these is independently a hydrogen atom, an alkyl group, an aryl group, a heteroaryl group, an alkoxy group, or a hydroxyl group.

3. In the above general formula (2), R ３ and R ４ The metal salt extractant according to claim 2, wherein each is independently an n-butyl group, a tert-butyl group, or a phenyl group.

4. A composition comprising a metal salt extractant and a non-aqueous solvent according to any one of claims 1 to 3.

5. A method for recovering a metal salt using a metal salt extractant according to any one of claims 1 to 3.

6. A method for separating at least one of a cuprous salt and a silver salt from a metal salt-containing material and producing at least one of a cuprous salt and a silver salt, A step of preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of claims 1 to 3, and a non-aqueous solvent, and A method for producing a metal salt, comprising the step of separating the mixture into solid and liquid phases to obtain a metal salt-containing liquid.

7. A method for separating at least one of a cuprous salt and a silver salt from a metal salt-containing material and producing at least one of a cuprous salt and a silver salt, A step of preparing a mixture comprising the metal salt-containing material, the metal salt extractant according to any one of claims 1 to 3, and a non-aqueous solvent. The process involves separating the mixture into solid and liquid components to obtain a metal salt-containing liquid, and A method for producing a metal salt, comprising the step of recovering the metal salt extractant from the metal salt-containing liquid.

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