JP2017119891A - Method for decomposing oxalate, and complex compound for decomposing oxalate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide means that thermally decomposes the oxalate of various transition metals at lower temperature to obtain transition metal atoms included in the oxalate as metals and the like.SOLUTION: A method for decomposing oxalate comprises a thermal decomposition step for heating a mixture comprising oxalate having a coordination polymer structure and amine having a primary amino group to decompose it.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for obtaining a metal or an oxide thereof by decomposing a metal oxalate, and a complex compound used in the process. The present invention also relates to a method for producing various forms of metals, oxides thereof and the like in the method.

  Waste industrial products and waste generated in the production process of industrial products contain various metal elements in various forms. It is particularly important to recover these and reuse them as industrial raw materials as metals from the viewpoints of environmental protection and resource protection, and various methods for separating and extracting various metals from various mixtures have been proposed. Further, depending on the use of the metal, it is necessary to reduce impurities contained in the target metal, and a method for easily producing a metal having a predetermined purity is desired. In the process of separation and purification of such metals, it is common to obtain the target metal through a plurality of chemical and physical processes by utilizing the difference in physical properties of each metal element.

  As one of the means used for the separation and purification of the metal, for example, in Patent Document 1, oxalic acid is added to an aqueous solution containing various transition metal ions under predetermined conditions to produce a metal oxalate. And a means for precipitating and separating the target metal as an oxalate using the low solubility of oxalate. The separated metal oxalate is then thermally decomposed in a reducing atmosphere to form a metal, or thermally decomposed in an oxidizing atmosphere to generate a metal oxide or the like and used for various applications. According to the means, separation according to the type of metal can be easily performed by utilizing the fact that the solubility of oxalate varies under various conditions depending on the type of metal. Moreover, since metal oxalate is thermally decomposed only by heat treatment without using a reducing agent or oxidizing agent that causes subsequent impurities and cost increase (Patent Documents 2 to 4), high purity metal Or as a raw material for metal oxides.

JP 51-125605 A JP 59-185770 A JP 2011-74410 A JP 2012-12619 A

H. Schmitter, Crystal Res. Technol. 19 (9) 1225-1230

As explained above, the method of obtaining metal and metal oxides by recovering metal elements present in aqueous solutions via oxalate is particularly small and more efficient than refining using the melting method. This is useful in that it enables the separation and purification of metal atoms.
However, for example, as described in Patent Documents 2 to 4, in order to thermally decompose the oxalate of a transition metal to obtain a metal or metal oxide, heat treatment at about 300 to 800 ° C. is still necessary. In addition, it becomes an obstacle in practical use, and particularly when obtaining metal, a predetermined facility is required to prevent reoxidation in the heat treatment process.
In order to solve such problems, the present invention is to thermally decompose oxalates of various transition metals at a lower temperature to obtain transition metal atoms contained in the oxalate as metals or the like. It is an object to provide the means.

The present invention is characterized by the following in order to solve the above problems.
That is, the present invention includes a thermal decomposition step of heating and decomposing a mixture containing an oxalate having a coordination polymer structure and an amine having a primary amino group, to decompose oxalate Regarding the method. According to the invention, the oxalate can be decomposed at a temperature lower than the decomposition temperature originally exhibited by the oxalate.

The present invention also relates to a method for decomposing oxalate having the following characteristics in the above method for decomposing oxalate.
(1) In the thermal decomposition step, a mixture of an oxalate having a coordination polymer structure and an amine having a primary amino group is heated to a first temperature to form a complex compound containing the oxalate and the amine. A first step and a second step of decomposing the complex compound by heating to a second temperature higher than the first temperature.
(2) At least a part of the pyrolysis step is performed in an inert gas atmosphere.
(3) As the amine having the primary amino group, an amine having at least one other substituent exhibiting electron donating properties is used.
(4) The substituent that exhibits the electron donating property is at least one substituent selected from a primary to tertiary amino group, a hydroxyl group, an alkoxyl group, a carboxyl group, and a phenyl group.
(5) The oxalate having the coordination polymer structure is a oxalate of the first transition metal.
(6) The first transition metal is at least one metal selected from V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.

The present invention also relates to a complex compound comprising an oxalate of a transition metal and an amine having a primary amino group. By using the complex compound, the transition metal atoms contained in the oxalate are separated by decomposing the oxalate at a temperature lower than the decomposition temperature originally exhibited by the oxalate of the transition metal contained in the complex compound. Is possible.
Furthermore, this invention relates to the complex compound which has the following each characteristics further in the said complex compound.
(1) The transition metal is a first transition metal.
(2) The first transition metal is at least one metal selected from V, Cr, Mn, Fe, Co, Ni, Cu and Zn.
(3) The amine having the primary amino group is an amine having another substituent that further exhibits an electron donating property.

  According to the present invention, it is possible to perform thermal decomposition of transition metal oxalates in a liquid phase under milder conditions than in the past, and it is possible to more easily obtain metals and the like from transition metal oxalates. It becomes possible. Moreover, the form of the metal etc. which are obtained can be controlled by interposing various substances in the environment which produces the thermal decomposition of the said oxalate.

It is a figure which shows the coordination polymer structure in copper oxalate. It is a figure which shows the structure of the complex compound of the copper oxalate obtained by this invention, and an amine. It is a figure which shows the result of the thermogravimetric analysis about the complex compound of (a) copper oxalate and (b) the copper oxalate obtained by this invention, and an amine. It is a figure which shows the X-ray-diffraction pattern of the complex compound of (a) copper oxalate and (b) the copper oxalate obtained by this invention, and an amine. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. In air | atmosphere) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. In air | atmosphere) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. Ar) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. Ar) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (2-aminoethanol. In air | atmosphere) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (2-aminoethanol. In air | atmosphere) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (2- (2-aminoethoxy) ethanol. In air | atmosphere) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (2- (2-aminoethoxy) ethanol. In air | atmosphere) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (oleylamine.in air | atmosphere) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (oleylamine. In air | atmosphere) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (2-ethylhexylamine. In air | atmosphere) of copper oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (2-ethylhexylamine. In air | atmosphere) of copper oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (2- (2-aminoethoxy) ethanol. In air | atmosphere) of nickel oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. In air | atmosphere) of iron oxalate. It is a figure which shows the transmission electron microscope image of the product produced | generated by decomposition | disassembly (N, N-diethyl- 1, 3- diaminopropane. In air | atmosphere) of iron oxalate. It is a figure which shows the X-ray-diffraction pattern of the product produced | generated by decomposition | disassembly (2- (2-aminoethoxy) ethanol in air | atmosphere) of oxo vanadium oxalate. It is a figure which shows the scanning electron microscope image of the product produced | generated by decomposition | disassembly (2- (2-aminoethoxy) ethanol in air | atmosphere) of oxo vanadium oxalate. It is a figure which shows the X-ray-diffraction pattern of the product at the time of decomposing | disassembling copper oxalate in Ar in presence of octanoic acid. It is a figure which shows the scanning electron microscope image of the product at the time of performing decomposition | disassembly of copper oxalate in Ar in presence of octanoic acid. The figure which shows the scanning electron microscope image of the copper thin film surface obtained by baking the product at the time of decomposition | disassembly of copper oxalate in Ar in presence of octanoic acid in Ar atmosphere at 220 degreeC. is there. It is a figure which shows the X-ray-diffraction pattern of the product at the time of decomposing | disassembling copper oxalate in air | atmosphere in presence of various amines. It is a figure which shows the scanning electron microscope image of the product at the time of performing decomposition | disassembly of copper oxalate in air | atmosphere in presence of various amines. The figure which shows the scanning electron microscope image of the copper thin film surface obtained by baking the product at the time of performing decomposition | disassembly of copper oxalate in air | atmosphere in presence of various amines in a reducing atmosphere at 200 degreeC. It is. It is a figure which shows the X-ray-diffraction pattern of the product at the time of decomposing | disassembling copper oxalate in Ar in presence of ethylene glycol. It is a figure which shows the scanning electron microscope image of the product at the time of performing decomposition | disassembly of copper oxalate in Ar in presence of ethylene glycol. The scanning electron microscope image of the copper thin film surface obtained by baking the product produced | generated when decomposition | disassembly of copper oxalate was performed in Ar in presence of ethylene glycol in Ar atmosphere at 220 degreeC is shown. FIG. It is a figure which shows the copper plate surface installed in the reaction system which decomposes | disassembles nickel oxalate, (a) Scanning electron microscope image, (b) Ni element mapping image, (c) Cu element mapping image.

The metal oxalate decomposition method according to the present invention will be described below.
The metal oxalate includes an oxalate ion ([COO] ₂ ²⁻ ) (anion) and a metal ion (M ^{n +} ) generated by ionization of oxalic acid ([COOH] ₂ ), where M represents a metal atom. , N is a valence of a metal atom) (cation), for example, in the case of a divalent metal oxalate, it is a substance represented by the chemical formula: MC ₂ O ₄ . When the metal oxalate is heated at a temperature higher than a predetermined temperature, the oxalic acid group (C ₂ O ₄ ) is generally decomposed to form carbon dioxide (CO ₂ ), carbon monoxide (CO), or the like. It is known that a decomposition reaction occurs in which a metal atom in a metallic state remains by desorbing to the outside. For this reason, it is easier to use as a source of metal atoms than metal oxides, and it is difficult to generate impurities during decomposition, so various metals as intermediate substances generated when separating metal atoms from various mixtures. Oxalates are widely used.

  Metal oxalates have various structures depending on the type of the metal, but especially in the oxalate salts of V, Cr, Mn, Fe, Co, Ni, Cu or Zn, which are the first transition metals, It is known that a coordinated polymer structure in which oxalic acid groups and metal atoms are alternately arranged as a result of further mutual coordination bond between oxalates (see, for example, Non-Patent Document 1) .)

Formula (1) shows a coordination polymer structure in copper oxalate. FIG. 1 shows a schematic diagram of a crystal structure formed by a coordination polymer structure in copper oxalate reported in Non-Patent Document 1 and the like.

  As shown in formula (1), copper oxalate is known to have a polymer molecular structure in which oxalic acid groups and metal atoms are alternately arranged in a chain. Moreover, as shown in FIG. 1, in the crystal of copper oxalate, it is known that the polymeric copper oxalate molecules are arranged in parallel to each other based on a relatively weak force.

The present inventor has studied various methods for decomposing metal oxalates. Surprisingly, oxalates having the coordination polymer structure as described above are heated in an environment containing a predetermined amine molecule. As a result, the present inventors have found that metal atoms can be generated by causing decomposition of oxalate at a temperature significantly lower than the decomposition temperature inherently exhibited by the oxalate.
Although the mechanism that causes the above phenomenon is not always clear, when oxalate having a coordination polymer structure and a predetermined amine are mixed and heated, oxalic acid is decomposed prior to the decomposition reaction of oxalate. Structural analysis shows that the properties of the salt, such as color and viscosity, change, and the coordination bond between oxalates is broken. As a result, the structure of oxalate is chemically unstable. It can be inferred that the decomposition temperature has decreased.

Utilizing the above phenomenon, in the present invention, an oxalate having a coordination polymer structure is decomposed by heating in an environment where a predetermined amine molecule is present, so that a normal oxalate decomposition temperature is obtained. The metal atoms contained in the oxalate can be recovered in various forms at a lower temperature. In other words, by controlling the atmosphere when decomposing oxalate or interposing molecules that affect the shape when metal atoms are deposited, the state of precipitates deposited from metal atoms can be reduced to metal. Or its shape can be manipulated. Further, by performing the oxalate decomposition reaction in contact with an appropriate solid surface, it is possible to selectively deposit metal atoms or the like on the surface, and it is also possible to perform surface treatment of the solid surface. .
As described above, the method of the present invention can easily decompose oxalate, which has been conventionally used for separating and purifying metals from wastes, and can directly produce useful metals and oxides thereof. It is useful in terms of facilitating metal reuse.
Hereinafter, the method for decomposing oxalate according to the present invention will be specifically described.

(Oxalate to which the present invention is applied)
The method for decomposing oxalate according to the present invention is applicable to metal oxalate having a coordination polymer structure in which oxalate molecules are linked in a chain by coordination bonds. Since many of the first transition metals widely used for various industrial purposes form oxalates having a coordination polymer structure, the present invention is preferably applied. Simplification and production of various functional materials becomes possible. That is, as described in Non-Patent Document 1 and the like, among the first transition metals, V, Cr, Mn, Fe, Co, Ni, Cu and Zn are oxalates having a coordination polymer structure. An oxalate salt having a coordination polymer structure is formed by introducing oxalate ions under predetermined conditions to an aqueous solution containing these metal ions. The oxalate can be collected in the state of metal or the like by the oxalate decomposition method.

(Decomposition mechanism of oxalate)
Oxalic acid at a temperature lower than the decomposition temperature of the oxalate by mixing the oxalate having the coordination polymer structure with an amine containing a predetermined amino group and heating to an appropriate temperature. It is possible to decompose the salt and precipitate the metal atom contained in the oxalate in another state such as metal. Specifically, when oxalate, which is solid at room temperature, and liquid amine are mixed, oxalate and amine exist as separate phases, while oxalate is heated in the process of heating the mixture. It is observed that the acid salt dissolves in the amine to form a homogeneous phase, and further heating causes a reaction involving the generation of carbon dioxide, carbon monoxide and the like, resulting in a new precipitate and the like. And according to the conditions at the time of decomposing | disassembling an oxalate, the said precipitate etc. can be made into a metal, an oxide, etc. of various shapes.

  In order to clarify the decomposition mechanism of oxalate according to the present invention as described above, the present inventors have conducted various studies. In the amine in which oxalate is dissolved, the oxalate single molecule Thus, it was confirmed that a complex compound in which an amine was coordinated was present. In other words, by mixing a certain amine with oxalate having a coordination polymer structure and heating, the coordination bond formed between the oxalate molecules is broken and the coordination bond with the amine molecule It was thought that complex compounds containing low molecular weight oxalates and monomolecular oxalates and amines were formed. And since the stability of the oxalic acid group in such a complex compound was low, it was thought that decomposition occurred at a temperature lower than the original decomposition temperature of oxalate.

  The mechanism by which the coordination polymer structure of oxalate is cleaved by an amine containing a specific amino group to form a complex compound containing an amine is not clear, but the metal is contained in the oxalate via the amino group. In order to easily form a coordinate bond to an atom and to easily donate an electron to the metal atom coordinated by the electron donating property of the amine, the amine is coordinated with the oxalate instead of the coordinate bond between the oxalate molecules. It is considered that the potential coupling occurs.

  That is, when an amine containing a primary amino group comes into contact with an oxalate having a coordination polymer structure at a predetermined temperature or higher, the amino group causes a coordinate bond to a metal atom in the oxalate. It is considered that the coordination bond between the oxalates is broken and a complex compound is formed in which an amine is coordinated to a metal atom in the oxalate. And, since the coordinate bond with the amine activates the bond between the oxalic acid group and the metal atom in an unstable manner, it is considered that the oxalate is decomposed at a lower temperature than the original.

(Amine for cleaving coordination polymer structure of oxalate)
In the present invention, the amine used for activating the oxalate by disrupting the coordination polymer structure to form a complex compound having a small molecular weight is an amine containing a primary amino group (or primary). (Also referred to as amine) is preferably used. In the present invention, the term amine containing a primary amino group means a molecule having at least one nitrogen atom (primary amino group) in which one hydrocarbon group and two hydrogens are bonded in the molecule. To do. In such an amine having a primary amino group, since the steric hindrance at the time of coordinate bonding to oxalate is small, a coordinate bond to oxalate is likely to occur. For this reason, it has been observed that complex compounds of oxalate and amine can be easily formed, which can activate the oxalate and lower the decomposition temperature. In the present invention, molecules containing one or more primary to tertiary amino groups are collectively referred to as amines regardless of their common names.

  As the amine containing a primary amino group used in the present invention, it is also preferable to use an amine having a substituent showing an electron donating property in the molecule. Examples of the substituent exhibiting electron donating properties include, but are not limited to, primary to tertiary amino groups, hydroxyl groups, alkoxyl groups, carboxyl groups, phenyl groups, and the like. A polyamine such as diamine or triamine corresponding to the case of further having a primary amino group can also be used. Moreover, although the substituent which shows electron withdrawing property shows the tendency to reduce the electron donating property which an amine shows, in order to adjust the electron donating property of an amine, you may have an electron withdrawing group. Any amine that can break a coordination bond between oxalate molecules alone or mixed with another amine can be used.

  In amines containing primary amino groups, as the molecular weight increases, the heating temperature for cleaving the coordination polymer structure increases, and the time required for cleaving the coordination polymer structure tends to increase. It is done. This is probably because the polarity generally decreases as the molecular weight increases, and the molecular mobility decreases. The amine that efficiently cleaves the coordination polymer structure depends on the type and arrangement of other functional groups contained in the molecule, but oxalic acid can be used as long as it contains approximately 18 or fewer carbon atoms. Salt decomposition can be facilitated. Further, by using an amine containing carbon having 12 or less carbon atoms, the coordination polymer structure can be cut more efficiently. In addition, when other substances are mixed with an amine for a predetermined purpose or when a coordination polymer structure is cleaved at a low temperature, a short-chain amine containing 6 or less carbon atoms may be used. desirable.

  In addition, as described below, by mixing a predetermined substance at the time of decomposition of oxalate, a metal atom generated by decomposition of oxalate is oxidized to an oxide, or a predetermined substance is added to the precipitate. It is possible to give a shape. When a predetermined substance is mixed with an oxalate together with the amine for such a purpose, the polarity of the amine possessed according to the polarity exhibited by the substance, etc., in order to facilitate mixing with the substance Is preferably taken into account.

Specific examples of the amine containing a primary amino group preferably used in the present invention include the following molecules, and these can be used alone or in combination. In other words, methylamine, ethylenediamine, ethylamine, propylamine, butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, tetradecylamine, pentadecylamine, hexadecyl Amine, octadecylamine, isopropylamine, 2-butylamine, isobutylamine, tert-butylamine, 1-methylbutylamine, 1-ethylpropylamine, 2-methylbutylamine, isoamylamine, 1,3-dimethylbutylamine, 3,3-dimethyl Butylamine, 2-aminoheptene, 3-aminoheptene, 2-ethylhexylamine, 1,5-dimethylhexylamine, tert-octylamine, 1, -Diaminopropane, 1,2-diaminopropane, 1,4-diaminobutane, 1,2-diamino-2-methylpropane, DYTEK EP Diamine, hexaethylenediamine, DYTEK A AMINE, 1,7-diaminoheptane, 1,8 -Diaminooctane, C, C, C, trimethyl-1,6-hexanediamine, 1,9-diaminononane, 1,10-diaminodecane, 1,12-diaminododecane, N-methylethylenediamine, N-ethylethylenediamine, n -Propylethylenediamine, N-isopropylethylenediamine, N, N-dimethylethylenediamine, N, N-diethylethylenediamine, N, N-dibutylethylenediamine, N, N-dipropylethylenediamine, N, N-dihexylethylenediamine, N, N-dioctyl Ethylenediamine, N-methyl-1,3-propanediamine, N-ethyl-1,3-propanediamine, N-butyl-1,3-propanediamine, N-propyl-1,3-propanediamine, N-isopropyl-1, 3-propanediamine, N-hexyl-1,3-propanediamine, N-octyl-1,3-propanediamine, 3-dimethylaminopropylamine, 3-diethylaminopropylamine, 3-dipropylaminopropylamido 3-dibutyl Aminopropylamine, N, N, 2,2, -tetramethyl-1,3-propanediamine, 2-butyl-ethyl-1,5-pentanediamine, 2-amino-5-diethylaminopentane, diethylenetriamine, N1-isopropyl Ethylenetriamine, N- (2-aminoethyl) -1,3-propanediamine 3,3-diamino-N-methyldipropylamine, N- (3-aminopropyl) -1,3-propanediamine, spermidine, bishexamethylenetriamine, 4- (aminomethyl) -1,8-octanediamine, Triethylenetetramine, 1,4,7,11, tetraazaundecane, N, N′-bis (2-aminoethyl) 1,3-propanediamine, N, N′-bis (3-aminopropyl) -1, 3-propanediamine, spermine, tris (2-aminoethyl) amine, tetraethylenepentamine, pentaethylenehexamine, cyclopropylamine, aminomethylcyclopropane, cyclobutylamine, cyclopentylamine, 5-amino-2,2,4- Trimethylpentaneethylamine, cyclohexylamine, 2-methylcyclohexyl Silamine, 2-ethylcyclohexylamine, 2-butylcyclohexylamine, 2-propylcyclohexylamine, 4-methylcyclohexylamine, 4-ethylcyclohexylamine, 4-propylcyclohexylamine, 4-butylcyclohexylamine, 4,4'-methylenebis (Hexylamine), 2,3-dimethylcyclohexylamine, cis-1,2-diaminocyclohexane, trans-1,2-diaminocyclohexane, cis-1,4-diaminocyclohexane, trans-1,4-diaminocyclohexane, cyclohexane Methylamine, 1-cyclohexylethyleneamine, 1,3-cyclohexanebismethylamine, N-cyclohexyl-1,3-propanediamine, 1,8-diamino-p-methane, 5 -Amino-1,3,3-trimethylcyclohexanemethylamine, cycloheptylamine, cyclooctylamine, cyclododecylamine, exo-aminolbornate, bornylamine, cis-miltanylamine, isopinocamphenylamine, 3-nor Adamantanamin, 1-adamantanamine, 2-adamantanamine, 3-adamantanamine, allylamine, oleylamine, geranylamine, 2- (1-cyclohexyl) ethylamine, 1-fluoroethylamine, 2-fluoroethylamine, 2, 2,2-trifluoroethylamine, 2,2,2-trichloroethylamine, 2-chloroethylamine, 2,2,2-tribromoethylamine, 2-bromoethylamine, 3-chloropropylamine, 3-bromopropylamine, 3 Fluoropropylamine, 2,5-dichloropropylamine, 2,5-dibromopropylamine, 2-methoxyethylamine, 2-butoxyethylamine, 3-methoxypropylamine, 2-ethoxyethylamine, 3-ethoxypropylamine, 3-butoxy Propylamine, 2-amino-1-methoxypropane, 3-isopropoxypropylamine, 3-isomethoxypropylamine, 3-isoethoxypropylamine, 2,2′-oxybis (ethylamine), 4,7,10-trioxa -1,13-tridecanediamine, 3-amino-1-propanol vinyl ether, tetrahydrofurfurylamine, 2,5-dihydro-2,5-dimethoxyfurfurylamine, aminoacetaldehyde dimethyl acetal, aminoacetaldehyde Diethyl acetal, aminobutyraldehyde diethyl acetal, methoxylamine, ethoxylamine, o-allylhydroxylamine, ethanolamine, 3-amino-1-propanol, 2-amino-1-propanol, 1-amino-2-propanol, 4- Amino-1-butanol, 2-amino-1-butanol, 2-amino-2-methyl-propanol, 5-amino-1-pentanol, 2-amino-1-pentanol, 2-amino-3-methyl- 1-butanol, 2-amino-3-methyl-1-butanol, 2-amino-3-methyl-1-butanol, 6-amino-1-hexanol, 2-amino-1-hexanol, isolevynol, tert-levynol, 6-amino-2-methyl-2-heptanol, serinol, 1 Amino-1-cyclopentanemethanol, 2-amino-3-cyclohexyl-1-propanol, trans-2-aminocyclohexanol, 3-aminomethyl-3,5,5-trimethylcyclohexanol, 2--2-aminomethylethanol 2- (methylamino) ethanol, 2- (propylamino) ethanol, 2- (tert-butylamino) ethanol, 3-amino-1,2-propanediol, serinol, serinol oxalate, 2-amino-2 -Ethyl-1,3-propanediol, 2-amino-2-methyl-1,3-propanediol, tris (hydroxymethyl) aminomethane, bis-homotris, 1,3-diamino-2-hydroxypropane, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethyl) Amino) -ethanol, 1-amino-1-deoxy-D-sorbitol, N-methyl-D-glucamine, 1-deoxy-1- (octylamino) -D-glucitol, D-galactosamine, D-glucosamine, D- Mannosamine, 2-aminoethanethiol, 1-amino-2-methyl-2-propanethiol, 2- (ethylthio) ethylamine, cystamine, methioninol, 1-aminopyrrolidine, 3-aminopyrrolidine, 2- (aminomethyl)- Pyrrolidine, 1- (2-aminoethyl) -pyrrolidine, 2- (2-aminoethyl) -pyrrolidine, 2- (2-aminoethyl) -1-methylpyrrolidine, 1-aminopiperidine, 1- (2-aminoethyl) ) Piperidine, 1- (3-aminopropyl) -2-pipecoline, 3-aminopiperidine, -(Aminomethyl) -piperidine, 4- (aminoethyl) -piperidine, 4- (aminobutyl) -piperidine, 4- (aminopropyl) -piperidine, 4- (aminohexyl) -piperidine, 1-amino-2, 6-dimethylpiperidine, 4-amino-2,2,6,6-tetramethylpiperidine, 1- (2-aminoethyl) piperazine, 1- (2-aminomethyl) piperazine, 1- (2-aminobutyl) piperazine 1- (2-aminopropyl) piperazine, 1,4-bis (2-aminomethyl) piperazine, 1,4-bis (2-aminoethyl) piperazine, 1,4-bis (2-aminobutyl) piperazine, 1,4-bis (2-aminopropyl) piperazine, hexetidine, 3-aminoquinuclidine, 2- (aminomethyl) 15-crown-5 4- (3-aminopropylmethyl) morpholine, 4- (3-aminoethyl) morpholine, 4- (3-aminopropyl) morpholine, 4- (3-aminobutyl) morpholine, 4- (3- Aminopentyl) morpholine, 4- (3-aminohexyl) morpholine, cis-4-amino-cyclohexanecarboxylic acid, glycine, alanine, arginine, asparagine, histidine, tryptophan, valine, phenylalanine, dopamine, dopa, aspartic acid, Glutamic acid, serine, threonine, cysteine, methionine, tert-leucine, norvaline, 2-amino-pentenoic acid, isoleucine, norleucine, 2-aminocapric acid, 3-aminoisobutyric acid, 5-aminovaleric acid , 6-aminocaproic acid, 7-aminoheptanoic acid, 8-aminocapric acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, carboxymethylamine, isoserine, homoserine, canavanine , 4-amino-3-hydroxybutyric acid, muramic acid, hydroxylysine, 1-amino-1-cyclopropanecarboxyl acid, 1-amino-1-cyclohexanecarboxyl acid, trans-4-aminocyclohexanecarboxyl Acid, 1-amino-1-cyclopentanecarboxylic acid, 5-amino-1,3-cyclohexanediene-1-carboxylic acid, 2-amino-2-norbornanecarboxyl Quadracid, β-alanine, 4-aminobutyric acid, 3-aminobutyric acid, α-aminocyclohexanepropionic acid, 2- (methylamino) isobutyric acid, 2- (methylamino) butyric acid, 2 -(Methylamino) ethyl acid, 2- (methylamino) propionic acid, 2,4-diaminobutyric acid, ornithine, N-ε-methyl-L-lysine, 2-methyl-glutamic acid, aminoadipic acid , Diaminopimeric acid, aminoadipic acid, penicillamine, homocysteine, ethionine, carboxymethylcysteine, cystine, ethyl-4-amino-1-piperidinecarboxylate, 6-aminopenicillanic acid, cycloserine, taurine, aminometa Sulfonic acid, 3-amino-1-propane sulfonic acid, aniline, o-toluidine, m-toluidine, p-toluidine, 2-isopropylaniline, 2-propylaniline, 2-butylaniline, 2-sec-butyl Aniline, 2-tert-butylaniline, 2-fluoroaniline, 2-bromoaniline, 2-chloroaniline, 2-methylmercaptoaniline, 2-aminobenzyl alcohol, 2-aminophenethyl alcohol, 2-phenetidine, 2-methylmercapto Aniline, 2-aminophenol disulfide, 2-isopropylaniline, toldin, 3-ethylaniline, 3-fluoroaniline, 3- (trifluoromethyl) aniline, 3-chloroaniline, 3-bromoaniline, 3-iodoaniline , M-anisidine, M-phenetidine, 3- (trifluoromethoxy) anily

, 3- (1,1,2,2, -tetrafluoroethoxy) aniline, 3-aminophenol, 3- (1-hydroxyethyl) aniline, 3-aminothiophenol, 3- (methylmercapto) aniline, toluidine 4-ethylaniline, 4-propylaniline, 4-pentylaniline, 4-hexylaniline, 4-heptylaniline, 4-hexadecylaniline, 4-cyclohexylaniline, 3,3′-methylenediamine, 4,4 '-Methylenediamine, 4,4'-methylenebis (3-chloro2,6diethylaniline), 4-fluoroaniline, 4-trifluoromethylaniline, 4-chloroaniline, 4-aminophenol, 4-bromoaniline, 4 -Iodoaniline, 4-aminothiophenol, 4-aminophenol, 4-methyl Lucaptoaniline, 4-aminothiophenyl disulfide, 2,3-dimethylaniline, 2,6-dimethylaniline, 1-amino-5,6,7,8, tetrahydronaphthalene, 2,6-dimethylaniline, 6-ethyl -O-toluidine, 2,6-diethylaniline, 2-isopropyl-6-methylaniline, 2,6-isopropylaniline, 2,6-isopropylaniline, phenethylamine, phenylpropylamine, diphenylpropylamine, phenylethylenediamine, phenylbutylamine, Phenylglycinol, phenylbutylamine, 4-aminobenzylamine, 4-methylbenzylamine, 4-xylenediamine, 4-methoxybenzylamine, 4-methoxyphenylethylamine, 4-aminobenzylamine, 4- ( Methylamino) benzyl amine, 3-methoxy phenethylamine, nor phenylephrine, dimethoxybenzyl amine, an amine selected from dihydroxybenzylamine can be used alone or a mixture of plural kinds.

  The amine having the primary amino group is used alone or mixed with an oxalate salt to be decomposed in a mixed state with another substance. When mixing with oxalate, it is desirable to mix only the amine having a primary amino group with oxalate, since the coordination polymer structure is cut early when the amine concentration is high. On the other hand, when a substance other than an amine is mixed and used for a predetermined purpose, it can be appropriately mixed and used within a range not inhibiting the decomposition of oxalate. Depending on the type of amine used, the concentration of the amine having a primary amino group in the mixture of the amine and other substances (hereinafter sometimes referred to as “amine bath”) is approximately 5 mol% or more. If present, it is preferable because a complex compound can be formed by cutting the coordination polymer structure. It is more preferable that the concentration of the primary amine is 10 mol% or more, particularly 30 mol% or more, because a complex compound can be generated at a sufficient rate.

  In addition, the amine bath can be used as an additive for substances that are not related to activation by cleavage of oxalate, such as oxidation of metal atoms caused by decomposition of oxalate and control of the form of precipitation. It can be used by mixing. It is also desirable that after the oxalate is activated, these additive substances are further mixed to cause oxalate degradation.

  Depending on the type (size and valence) of the metal atom contained in one molecule of oxalate produced by cleaving the coordination polymer structure, usually 1 to 4 molecules of amine are coordinated. To form a complex compound. For this reason, the amount of amine to be used is set to be not less than the amount (hereinafter referred to as “equivalent amount”) in which all of the oxalate used is a complex compound in consideration of the coordination number to the oxalate. preferable. There is no upper limit to the amount of amine to be used, and an excess amount of amine can be used at an appropriate ratio, but in practice it is preferable to use 2 to 5 times the equivalent amount of amine mixed with oxalate. In addition, when the complex compound in which an amine is coordinated to oxalate is further heated to thermally decompose the oxalate, the amine coordinated due to aggregation of the resulting metal atoms as a metal or the like It has been observed that it is released into the system. For this reason, even when amine equal to or less than oxalate is used, it is possible to decompose all oxalate by continuously heating.

(Coordination polymer structure cutting process)
In the method for decomposing oxalate according to the present invention, an oxalate having a coordination polymer structure is mixed with only an amine having a primary amino group or an amine bath containing the amine and another substance. A step of cleaving and activating the coordination polymer structure with an amine. Depending on the type of amine used, the reaction between oxalate and amine is considered to partially proceed near room temperature, but as shown in the examples, oxalates of transition metals are generally stable and active near room temperature. Since it is difficult to complete the conversion, in the present invention, it is preferable to activate the oxalate with an amine in a predetermined heating state from the viewpoint of not leaving the unactivated oxalate.

  The activation of the coordination polymer structure of oxalate by cleaving with an amine depends on the type and concentration of the amine used, the type of oxalate used, the degree of aggregation, etc. Activation is completed by stirring for about 30 minutes to 1 hour in the range of 200 ° C, typically in the range of 50 to 120 ° C. In order to determine a specific heating temperature, it is preferable to select the vicinity immediately above the temperature at which the coordination polymer structure of oxalate is cut and a complex compound is favorably generated from the viewpoint of causing a uniform reaction.

Completion of activation of the oxalate can be judged by the disappearance of the solid oxalate and the change in the color, viscosity, etc. of the mixture of oxalate and amine. In other words, oxalate with a coordination polymer structure exists as a solid without dissolving in amine, whereas it generates a complex compound consisting of oxalate and amine by activation to form a homogeneous phase. Generally, it is considered to exhibit different colors and viscosities.
When metal atoms generated by the decomposition of oxalate are precipitated in a metallic state or when it is desired to suppress the dissolved oxygen concentration, the formation of complex compounds such as Ar atmosphere is prevented in order to prevent dissolution of oxygen and the like in the system. It is preferable to carry out in an inert atmosphere.

  FIG. 2 shows an example of the structure of a complex compound of copper oxalate and amine obtained by performing the treatment with amine in the example of the present invention. FIG. 2 is a structure obtained by X-ray structural analysis of a single crystal obtained by recrystallizing a material obtained by treating copper oxalate with N, N-diethyl-1,3-diaminopropane. is there. As shown in FIG. 2, copper oxalate becomes a single molecule by the treatment with amine, and the copper atom and two molecules of primary amino group of N, N-diethyl-1,3-diaminopropane form a coordinate bond. You can see that it has occurred.

(Decomposition of oxalate)
Oxalic acid at a temperature lower than the temperature at which the oxalate having a coordination polymer structure undergoes thermal decomposition by heating the oxalate-amine complex compound obtained above alone or in an appropriate reaction medium The salt can be pyrolyzed. In this thermal decomposition, the oxalic acid group constituting the oxalate is decomposed and released as carbon dioxide or the like, so that the metal atom bonded to the oxalic acid group is released. The released metal atoms can be deposited in a metallic state by adjusting the atmosphere at the time of pyrolysis, depending on the purpose of subsequent use, or in the form of oxides, sulfides, etc. .

  The process of cleaving and activating the coordination polymer structure of oxalate and the process of thermally decomposing the resulting oxalate-amine complex by heating gradually heats the mixture of oxalate and amine. It is also possible to carry out continuously in the process of carrying out, or to carry out separately. When both steps are performed successively, it is preferable to change the temperature so as to reach the decomposition start temperature of the complex compound after the formation of the complex compound of amine and oxalate is completed. On the other hand, particularly when it takes time to generate the complex compound, the generation is completed by maintaining the first temperature for generating the complex compound of amine and oxalate, and then higher than the first temperature. It is preferable to decompose the oxalate by performing an operation such as heating to the second temperature.

  In addition, for example, when a desired substance is interposed during the decomposition of oxalate for the purpose of precipitating metal oxide by decomposition of oxalate, the two steps are separated, It is also possible to decompose the oxalate salt by dividing the coordination polymer structure to form a complex compound of oxalate, and then adding the substance and heating. For example, when the surface of a desired article is coated with metal atoms generated by decomposition of oxalate, the oxalate complex compound produced in advance is brought into contact with the surface of the article and heated. Is possible. In particular, when a metal layer having a predetermined shape such as an electrode or wiring is attached to the surface of the article, it is possible to draw a desired shape with a pre-generated complex compound of oxalate and then perform heating. is there.

  The temperature at which the oxalate complex compound is decomposed by heating is not particularly limited in the range in which the decomposition reaction occurs, but from the point of causing a uniform reaction in the system, it is just above the decomposition start temperature of each complex compound. Preferably it is done.

  When recovering metal atoms generated by the decomposition of oxalate as metal, it is effective to perform a series of steps in an inert gas atmosphere such as Ar in order to prevent oxidation of the metal atoms. is there. On the other hand, when recovering as an oxide, in addition to decomposing in the air, oxalate is decomposed in an atmosphere with an increased oxygen partial pressure, or mixed with water or hydrogen peroxide. It is effective to perform decomposition. Moreover, when recovering as a sulfide, oxalate can be decomposed in an appropriate environment according to the substance to be recovered, such as mixing a sulfurizing agent such as thiouric acid.

  The metal obtained by decomposing oxalate according to the present invention is present in a reaction medium containing an amine that is separated during the decomposition of oxalate. Can be separated. In particular, when the oxidant is not mixed, the amine used for the cleavage of the coordination polymer structure does not participate in the oxalate decomposition reaction, and the by-product generated by the decomposition of the oxalate is Since it is released out of the system as carbon dioxide or the like, it is possible to recover the amine separated from the complex compound by decomposition of the oxalate and use it again for the cleavage of the coordination polymer structure.

  FIG. 3 shows the thermal decomposition behavior of the case where the coordinating polymer structure copper oxalate was directly pyrolyzed and the case where the coordinating polymer structure was previously cut into a complex compound containing copper oxalate. As an example, the result of thermogravimetric analysis is shown. As shown in FIG. 3, untreated copper oxalate (a) undergoes thermal decomposition at about 300 ° C. and releases carbon dioxide, resulting in a weight loss. On the other hand, treatment with amine was performed. Since copper oxalate (b) releases carbon dioxide in a temperature range of about 120 to 170 ° C. and weight loss occurs, the thermal decomposition temperature of copper oxalate decreases by performing the treatment according to the method of the present invention. I understand that.

  As is clear from the results shown in FIG. 3, according to the present invention, it becomes possible to decompose at a significantly lower temperature compared to untreated oxalate, and separation and recovery of metal elements via oxalate can be achieved. It becomes possible to perform more simply and with low energy. In particular, since decomposition occurs at a low temperature of about 100 to 200 ° C., the reaction can be performed using waste heat of an industrial process and the like, and it is considered to be a means for generating useful substances with a low environmental load. . In addition, since the method for decomposing oxalate according to the present invention is a thermal decomposition reaction of oxalate itself, substances such as amines involved in the method are basically not consumed, and impurities to the product obtained by decomposition Since there is little contamination, it is considered to be a means of low environmental load, low cost, and high quality.

According to the present invention, metal oxalate is used as a raw material, and it is possible to recover the metal atoms contained in the oxalate as oxides and sulfides in addition to the metal form by decomposing it. It can be used as various industrial materials.
In addition, since the decomposition of oxalate according to the present invention is performed at a relatively low temperature and under mild conditions, organic molecules or material surfaces that have various effects on the precipitation process of metal atoms and the like are interposed during the decomposition. By doing so, it is possible to easily control the form of the metal or the like deposited by the decomposition of the oxalate.

  For example, when metal is deposited by decomposition of oxalate, a component that functions as a capping molecule that coats the metal surface and prevents growth beyond a certain level by coordinating bonds on the surface of the deposited metal is mixed. By doing so, metal fine particles having a particle size of several hundred nm or less can be generated. Since the metal fine particles obtained by decomposing oxalate according to the present invention suppress the impurity component, they can be used as high-purity metal fine particles by selecting appropriate capping molecules and suppressing surface oxidation after generation. Is possible. In addition, by decomposing oxalate in an environment where polar molecules that have a predetermined arrangement in the medium exist, a template for depositing metal atoms is formed, and metal particles having an appropriate shape are deposited. be able to. By mixing these particles with an appropriate dispersion medium, it is useful as an ink or paste that is sintered to form a metal film. The present invention is also useful when forming a metal catalyst or the like by taking advantage of the large specific surface area of the deposited metal fine particles. On the other hand, by causing decomposition of oxalate on the surface of metal or the like, the generated metal atoms can deposit the metal on the surface, and the surface can be covered.

  In addition, oxide fine particles of various metals can be deposited by decomposing oxalate in an oxidizing atmosphere. Among these oxide fine particles, for example, magnetic particles can be used as materials for magnetic materials, electronic materials and magnetic fluids, and can be suitably used for biomedical purposes by fixing various physiologically active substances on the surface. Particles can be generated. Further, it can be used as a catalyst by depositing it as an oxide on a support such as another metal oxide or fixing the precipitated oxide fine particles.

  Hereinafter, the present invention will be specifically described based on examples. The following embodiment is an example of the present invention, and the present invention is not limited to this, and various forms can be adopted.

[Example 1]
By mixing oxalic acid dihydrate (Kanto Chemical Co., Ltd.) into an aqueous solution of copper sulfate pentahydrate (Kanto Chemical Co., Ltd.), copper oxalate 0.5 hydrate copper oxalate A product was produced and precipitated, separated by filtration, sufficiently washed with pure water and dried, and used for the following evaluations.
1.72 g (13.2 mmol) of N, N-diethyl-1,3-diaminopropane (Tokyo Kasei) as an amine having a primary amino group and 1.00 g (6.23 mmol) of copper oxalate synthesized above. After mixing, the mixture was heated and stirred for about 1 hour on a hot stirrer adjusted to 120 ° C. under the atmosphere. By heating, the light blue copper oxalate was gradually dissolved to form a deep blue paste. Then, it took out from the hot stirrer, the reaction was terminated by natural cooling, and a dark blue solid was obtained.

FIG. 2 shows the molecular structure obtained by X-ray structural analysis of the crystal grains obtained by heating the obtained dark blue solid, gradually cooling it after melting, and recrystallizing it. As shown in FIG. 2, the coordinating polymer structure inherent to copper oxalate is not observed after the mixing, and two amine molecules are added to the copper atom of a copper oxalate molecule composed of a pair of oxalic acid groups and copper atoms. A mononuclear complex structure in which is coordinated by an amino group was observed.
FIG. 4 shows the results of powder X-ray diffraction (Rigaku MiniFlex II) of the copper oxalate (a) used and the dark blue solid (b) obtained above. As shown in FIG. 4, the solid obtained by the above mixing showed a diffraction pattern different from that of the original oxalate, and also from this point, the structure of copper oxalate was changed by mixing with amine. Is shown.
Next, when the deep blue solid obtained above was heated and stirred on a hot stirrer adjusted to 160 ° C., a reaction for releasing carbon dioxide occurred. After heating and stirring for 3 hours, the mixture was allowed to cool naturally, and 3 mL of hexane (Kanto Chemical Co., Ltd.) was added and centrifuged to obtain a precipitate. Further, 3 mL of 1-propanol (Kanto Chemical Co., Ltd., special grade) was added to the resulting precipitate for redispersion, followed by centrifugation again, and the resulting precipitate was dried under reduced pressure to obtain a product. The obtained sample was evaluated by a powder X-ray diffractometer and a scanning electron microscope (JEOL JSM7600F).
In FIG. 5, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as a mixture of metallic copper and copper (I) oxide. FIG. 6 shows a scanning electron microscope image of the product. The product was an aggregate of crystals having a particle size of about 50 to 100 nm.
The weight change shown in FIG. 3 is a weight change when the dark blue solid (b) obtained as described above and untreated copper oxalate (a) are heated in Ar. As shown in FIG. 3, in the case of copper oxalate that is not treated, the weight loss caused by decomposition occurs at about 300 ° C., whereas the dark blue solid obtained above causes weight loss from around 140 ° C. Indicated.
As described above, the complex compound is formed by mixing and heating copper oxalate and N, N-diethyl-1,3-diaminopropane which is a kind of amine having a primary amino group, It was shown that by heating this complex compound, copper oxalate decomposes at a temperature significantly lower than the original decomposition temperature of copper oxalate to produce copper atoms, and metallic copper and the like are deposited.

[Example 2]
The copper oxalate was decomposed in the same manner as in Example 1 except that the mixture of the mixed N, N-diethyl-1,3-diaminopropane and copper oxalate was heated in an Ar stream.
N, N-diethyl-1,3-diaminopropane (Tokyo Kasei) 1.72 g (13.2 mmol) and copper oxalate hemihydrate 1.00 g (6.23 mmol) were mixed, and Ar gas was passed through. The mixture was stirred for 1 hour on a hot stirrer adjusted to 120 ° C., and further heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally. After cooling, 3 mL of hexane was added for centrifugation, and 3 mL of propanol was added to the resulting precipitate for redispersion, followed by centrifugation again, and the resulting precipitate was dried under reduced pressure to obtain a product. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 7, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper containing trace amounts of copper (I) oxide. FIG. 8 shows a scanning electron microscope image of the product. The product was in the form of coarse particles having a particle size of about 100 nm to several μm.
As is clear from the comparison with Example 1, in the process of decomposition of copper oxalate according to the present invention, the supply of oxygen from the atmosphere is interrupted to suppress the production of copper oxide and produce metallic copper. It was shown that.

[Example 3]
Copper oxalate was decomposed in the same manner as in Example 1 except that 2-aminoethanol was used as the amine having a primary amino group used for the decomposition of copper oxalate.
1.23 g (20.1 mmol) of 2-aminoethanol (Wako Pure Chemicals, special grade) and 1.00 g (6.23 mmol) of copper oxalate hemihydrate were mixed and adjusted to 60 ° C. in the atmosphere. After stirring for 1 hour on a hot stirrer, the mixture was further heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally. After cooling, 3 mL of distilled water is added, followed by centrifugation. After 3 mL of distilled water is added to the resulting precipitate for redispersion, the mixture is centrifuged again, and the resulting precipitate is dried under reduced pressure. Obtained. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 9, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper, and no diffraction peak due to copper (I) oxide or the like was observed. FIG. 10 shows a scanning electron microscope image of the product. The product was coarse particles having a particle size of about several μm.
As is clear from the comparison with Example 1, by using 2-aminoethanol as the amine used for the decomposition of copper oxalate according to the present invention, the oxidation of copper was also performed when copper oxalate was decomposed in the atmosphere. It was shown that metallic copper containing no copper oxide was produced.

[Example 4]
Copper oxalate was decomposed in the same manner as in Example 1 except that 2- (2-aminoethoxy) ethanol was used as the amine having a primary amino group used for the decomposition of copper oxalate. That is, 2.10 g (20.0 mmol) of 2- (2-aminoethoxy) ethanol (Tokyo Kasei, Grade 1) and 1.00 g (6.23 mmol) of copper oxalate hemihydrate are mixed in the atmosphere. The mixture was stirred on a hot stirrer adjusted to 60 ° C. for 1 hour, further heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally. After cooling, 3 mL of methanol (Kanto Chemical Co., Ltd., special grade) was added, followed by centrifugation. After adding 3 mL of methanol to the resulting precipitate and redispersing it, the mixture was centrifuged again and the resulting precipitate was dried under reduced pressure. The product was obtained. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 11, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper, and no diffraction peak due to copper (I) oxide or the like was observed. FIG. 12 shows a scanning electron microscope image of the product. The product was coarse particles having a particle size of about several μm.
As is clear from comparison with Example 1, when 2- (2-aminoethoxy) ethanol was used as the amine used for the decomposition of copper oxalate according to the present invention, copper oxalate was decomposed in the atmosphere. It was also shown that copper oxidation was suppressed and metal copper containing no copper oxide was produced.

[Example 5]
Copper oxalate was decomposed using oleylamine as an amine having a primary amino group used for decomposition of copper oxalate.
Oleylamine (Kanto Chemical, purity 80-90%) 5.31 g (19.9 mmol) and copper oxalate hemihydrate 1.00 g (6.23 mmol) were mixed and adjusted to 120 ° C. in the atmosphere. After stirring for 1 hour on a hot stirrer, the mixture was further heated and stirred at 180 ° C. for 3 hours, and then allowed to cool naturally. After cooling, add 3 mL of hexane (Kanto Chemical Co., Ltd., 1st grade), then perform centrifugation. Add 3 mL of hexane to the resulting precipitate, re-disperse it, and then centrifuge again. The product was obtained by drying. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 13, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as a mixture of metallic copper and copper (I) oxide. FIG. 14 shows a scanning electron microscope image of the product. The product was agglomerated of particles having a particle size of about several tens of nanometers.
By using oleylamine having a large molecular weight as the amine used for the decomposition of copper oxalate according to the present invention, the temperature required for the decomposition of copper oxalate tends to increase, and the ratio of copper oxide in the product increases. It was shown that oxidation is likely to occur.

[Example 6]
Copper oxalate was decomposed using 2-ethylhexylamine as an amine having a primary amino group used for decomposition of copper oxalate.
Mix 2.57 g (19.9 mmol) of 2-ethylhexylamine (Tokyo Kasei, purity 98% or more) and 1.00 g (6.23 mmol) of copper oxalate 0.5 hydrate and adjust to 120 ° C. in the atmosphere. After stirring for 1 hour on the hot stirrer, the mixture was further heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally. After cooling, add 3 mL of hexane (Kanto Chemical Co., Ltd., 1st grade), then perform centrifugation. Add 3 mL of hexane to the resulting precipitate, re-disperse it, and then centrifuge again. The product was obtained by drying. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 15, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as copper (I) oxide partially containing metallic copper. FIG. 16 shows a scanning electron microscope image of the product. The product was an agglomeration of fine particles.
It was shown that by using 2-ethylhexylamine as the amine used for the decomposition of copper oxalate according to the present invention, almost all copper atoms are oxidized during the decomposition of oxalate, which is suitable for the production of copper oxide.

[Examples 7 to 10]
Isopropylamine (Example 7), hexylamine (Example 8), dodecylamine (Example 9), and phenylethylamine (Example 10) were used as amines having primary amino groups used for the decomposition of copper oxalate, respectively. The copper oxalate was decomposed.
In the experiment, copper oxalate 0.5 hydrate was mixed with each of the above amines in an amount of about 3 times, and the mixture was stirred for 1 hour on a hot stirrer adjusted to 120 ° C. in the atmosphere. The mixture was heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally, thereby confirming whether copper oxalate could be decomposed.

  As a result, when isopropylamine and hexylamine were used, the color of copper oxalate started to change from pale light blue to blue when mixed with copper oxalate at room temperature, and then completely changed to blue by stirring at 120 ° C. As a result, the viscosity of the mixture also changed. On the other hand, when dodecylamine or phenylethylamine is used, there is no change in copper oxalate when mixed at room temperature, and it turns blue when stirred at 120 ° C, resulting in a change in the viscosity of the mixture. It was. Then, it was observed that the subsequent stirring at 160 ° C. produced a precipitate with carbon dioxide release, resulting in the decomposition of copper oxalate.

[Comparative Examples 1-4]
Instead of the amine having a primary amino group used for the decomposition of copper oxalate, diethylamine having a secondary amino group (Comparative Example 1), dipropylamine (Comparative Example 2), and triethylamine having a tertiary amino group ( An attempt was made to decompose copper oxalate using Comparative Example 3). Moreover, decomposition | disassembly of copper oxalate was tried using oleic acid (Comparative Example 4) which is monovalent carboxylic acid.
In Comparative Examples 1 to 3, a hot stirrer adjusted to 120 ° C. in the atmosphere by mixing copper oxalate 0.5 hydrate with an amount corresponding to about 3 times the equivalent of each of the above amines. After stirring for 1 hour above, the mixture was further heated and stirred at 160 ° C. for 3 hours, and then allowed to cool naturally, thereby confirming whether or not copper oxalate could be decomposed.
In Comparative Example 4, 2.3 times equivalent amount of oleic acid was mixed with copper oxalate, stirred for 2 hours on a hot stirrer adjusted to 200 ° C. in the atmosphere, and further heated and stirred at 250 ° C. for 2 hours. Then, it was confirmed that the copper oxalate can be decomposed by naturally cooling.
As a result of the above examinations, no reaction accompanied by the release of carbon dioxide occurred in any case, and effective decomposition of copper oxalate could not be confirmed.

[Example 11]
Nickel oxalate, which is a nickel oxalate, was decomposed by the method of the present invention to obtain metallic nickel.
To 0.73 g (4.0 mmol) of nickel oxalate dihydrate (Mitsuwa Chemical purity 99% or more), 2.52 g of 2- (2-aminoethoxy) ethanol as an amine containing a primary amino group (24. 0 mmol), and the mixture was stirred for 1 hour on a hot stirrer adjusted to 90 ° C. in the atmosphere, further heated and stirred at 200 ° C. for 5 hours, and then allowed to cool naturally. After cooling, 3 mL of ethanol was added, followed by centrifugation. After 3 mL of methanol was added to the resulting precipitate for redispersion, the mixture was centrifuged again, and the resulting precipitate was dried under reduced pressure to obtain a product. . The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

  In FIG. 17, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The diffraction peaks of the product were all attributed to metallic nickel, and no oxide phase was confirmed.

[Example 12]
Iron oxalate, which is an iron oxalate, was decomposed by the method of the present invention to obtain iron oxide.
To 1.44 g (8.0 mmol) of iron oxalate dihydrate (Wako Pure Chemical Industries, Ltd.), 4.32 g (33.N) of N, N-diethyl-1,3-diaminopropane as an amine containing a primary amino group. 2 mmol), and 0.1 g (0.35 mmol) of oleic acid added thereto were stirred for 1 hour on a hot stirrer adjusted to 120 ° C. in the atmosphere, and further heated and stirred at 170 ° C. for 5 hours. And then allowed to cool naturally. After cooling, 3 mL of ethanol was added, followed by centrifugation. After 3 mL of methanol was added to the resulting precipitate for redispersion, the mixture was centrifuged again, and the resulting precipitate was dried under reduced pressure to obtain a product. . The obtained product was evaluated with a powder X-ray diffractometer and a transmission electron microscope.

  In FIG. 18, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The diffraction peak of the product was assigned to spinel iron oxide. FIG. 19 shows a transmission electron microscope image of the product. As shown in FIG. 19, the product was a monodispersed fine particle having a particle diameter of 10 nm.

[Example 13]
Oxovanadium oxalate, which is an oxalate salt of vanadium, was decomposed by the method of the present invention to obtain an oxide.
Vanadium oxyoxalate.n hydrate (Mitsuwa Chemical (anhydride content 70.6%)) 0.869 g (4.0 mmol) as 2- (2-aminoethoxy) amine containing primary amino group A mixture of 1.68 g (16.0 mmol) of ethanol was stirred for 1 hour on a hot stirrer adjusted to 100 ° C. in the air, further heated and stirred at 190 ° C. for 2 hours, and then allowed to cool naturally. . After cooling, 3 mL of ethanol was added, followed by centrifugation. After 3 mL of methanol was added to the resulting precipitate for redispersion, the mixture was centrifuged again, and the resulting precipitate was dried under reduced pressure to obtain a product. . The obtained product was evaluated with a powder X-ray diffractometer and a transmission electron microscope.

In FIG. 20, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. As for the diffraction peak of the product, diffraction lines attributed to vanadium oxide (VO ₂ , V ₃ O ₇ ) and the like were confirmed. FIG. 21 shows a scanning electron microscope image of the product. As shown in FIG. 21, the product was a collection of crystals of several hundred nm in several μm.

[Example 14]
In the following examples, in the system in which the decomposition of oxalate was observed as described above, the shape of the product was manipulated by adding a substance that particularly affects the shape of the product.
In this example, octanoic acid, which is a monovalent carboxylic acid, is added to a reaction system for decomposing copper oxalate to form a capping molecule that prevents coarsening when metallic copper is precipitated, and the precipitated copper fine particles Manipulated the shape.
3.24 g (24.9 mmol) of N, N-diethyl-1,3-diaminopropane (Tokyo Kasei) and 1.00 g (6.23 mmol) of copper oxalate hemihydrate were mixed and further used as a capping molecule. A mixture of 0.9 g (6.24 mmol) of octanoic acid (Tokyo Kasei) was stirred for 1 hour on a hot stirrer adjusted to 120 ° C. while allowing Ar gas to flow, and then heated at 170 ° C. for 2 hours. The mixture was stirred and then allowed to cool naturally. After cooling, 3 mL of hexane was added for centrifugation, and 3 mL of propanol was added to the resulting precipitate for redispersion, followed by centrifugation again, and the resulting precipitate was dried under reduced pressure to obtain a product. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 22, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper. FIG. 23 shows a scanning electron microscope image of the product. The product was in the form of particles having a particle size of about several hundred nm.
Next, the copper fine particles deposited by the above method are added to about 50 wt% with respect to Telsolve THA90 to form a copper-containing paste, which is applied to a glass substrate by a bar coating method, and then an infrared furnace substituted with argon gas is used. The copper thin film was obtained by firing at each temperature shown in Table 1 for 1 hour. The obtained copper thin film was evaluated with a scanning electron microscope, and the conductivity was evaluated with a surface resistance measuring device (Kyowa Riken K-705RS).

As shown in Table 1, substantial conductivity is produced even by firing at about 180 ° C., and in particular, by conducting firing at 220 ° C. or higher, the conductivity is about 1/10 or higher compared to bulk metallic copper. It turns out that it expresses sex. In FIG. 24, the scanning electron microscope image of the copper thin film surface obtained by baking at 220 degreeC after apply | coating the said copper containing paste is shown. As shown in FIG. 24, the copper fine particles were fused to each other without being grain-grown by firing, and this was considered to cause macroscopic conductivity.
As shown in the above results, when the copper oxalate is decomposed according to the present invention, it is possible to make the metal copper precipitated by mixing the capping molecules into fine particles, and the copper fine particles are high. It became clear to show sinterability.

[Example 15]
In this example, as compared with Example 14, the capping molecule was changed and a plurality of amines involved in the decomposition of copper oxalate were used to decompose copper oxalate in the atmosphere.
As amines having a primary amino group, N, N-diethyl-1,3-diaminopropane (Tokyo Kasei) 2.89 g (22.2 mmol), octylamine (Acros Organics) 2.00 g (15.5 mmol), A mixture of 0.460 g (2.48 mmol) of dodecylamine (Tokyo Kasei, special grade) was used. To this mixture, 2.00 g (12.5 mmol) of copper oxalate hemihydrate was mixed, and 0.15 g (0.531 mmol) of oleic acid (Tokyo Kasei, special grade) as a capping molecule was further added. After stirring for 1 hour on a hot stirrer adjusted to 120 ° C. in the air, the mixture was further heated and stirred at 170 ° C. for 2 hours, and then allowed to cool naturally. After cooling, 3 mL of hexane was added for centrifugation, and 3 mL of propanol was added to the resulting precipitate for redispersion, followed by centrifugation again, and the resulting precipitate was dried under reduced pressure to obtain a product. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 25, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper partially containing copper (I) oxide. FIG. 26 shows a scanning electron microscope image of the product. The product was in the form of particles having a particle size of about 100 nm.
Next, the copper fine particles precipitated by the above method are added to a mixed solvent mixed so as to be butanol: octane = 1: 4 (volume ratio) so as to be about 50 wt% to obtain a copper ink, and spin coating is applied to a glass substrate. After coating, a copper thin film was obtained by firing at each temperature shown in Table 2 for 1 hour using an infrared furnace substituted with a reducing atmosphere of 5% hydrogen / 95% nitrogen. The obtained copper thin film was evaluated with a scanning electron microscope, and the conductivity was evaluated with a sheet resistance measuring device.

As shown in Table 2, it can be seen that even when firing at about 160 ° C., good conductivity is produced, and particularly when firing at 200 ° C. or higher, volume resistance close to that of bulk metallic copper is exhibited. In FIG. 27, the scanning electron microscope image of the copper thin film surface obtained by baking at 220 degreeC after apply | coating the said copper containing paste is shown. As shown in FIG. 27, it was considered that copper fine particles were grown and fused to each other by firing, and this caused macroscopic conductivity.
As shown in the above results, it is possible to produce metal copper fine particles even in the atmosphere by considering amines and capping molecules used in decomposing copper oxalate according to the present invention, and the copper. It became clear that the fine particles showed high sinterability.

[Example 16]
In this example, copper oxalate was decomposed in the same manner as in Example 14 using ethylene glycol as a template material, and the sinterability of the obtained product was evaluated.
N, N-diethyl-1,3-diaminopropane (Tokyo Kasei) 1.72 g (13.2 mmol) and copper oxalate 0.5 hydrate 0.5 g (3.1 mmol) were mixed and further used as a template material. After adding 4 mL of ethylene glycol (Kanto Chemical Co., Ltd., special grade) for 1 hour on a hot stirrer adjusted to 120 ° C. while allowing Ar gas to flow, it was further heated and stirred at 160 ° C. for 3 hours. Allowed to cool naturally. After cooling, 3 mL of hexane was added for centrifugation, and 3 mL of propanol was added to the resulting precipitate for redispersion, followed by centrifugation again, and the resulting precipitate was dried under reduced pressure to obtain a product. The obtained product was evaluated with a powder X-ray diffractometer and a scanning electron microscope.

In FIG. 28, the diffraction pattern by the powder X-ray diffractometer of the said product is shown. The product was identified as metallic copper. FIG. 29 shows a scanning electron microscope image of the product. The product was flaked with a spread of about 10 μm.
Next, flaky metallic copper deposited by the above method is added to about 30 wt% with respect to Telsolve THA90 to form a copper-containing paste, which is applied to a glass substrate by a bar coating method, and then infrared gas-substituted infrared is substituted. A copper thin film was obtained by firing for 1 hour at each temperature shown in Table 3 using a furnace. The obtained copper thin film was evaluated with a scanning electron microscope, and the conductivity was evaluated with a sheet resistance measuring device.

As shown in Table 3, although the flaky copper fine particles obtained in this example have a small decrease in resistance value due to firing compared to the above copper fine particles, sufficient conductivity is obtained by firing at about 200 ° C. It turns out that it expresses. FIG. 30 shows a scanning electron microscope image of the surface of the copper thin film obtained by applying the copper-containing paste and firing at 220 ° C. As shown in FIG. 30, it was observed that the flaky metallic copper was deformed so as to reduce the surface area, and it was considered that macro-conductivity was caused by partial fusion.
As shown in the above results, when copper oxalate is decomposed according to the present invention, it is possible to make the metal copper deposited by mixing the template material into a flake shape, and the copper fine particles are highly baked. It became clear that it showed cohesion.

[Example 17]
In this example, nickel oxalate was decomposed in an environment where a copper substrate was present, and metallic nickel was deposited on the copper surface.
Nickel oxalate dihydrate (Mitsuwa Chemical purity 99% or more) 0.10 g (0.5 mmol) was mixed with 2.00 g (32.7 mmol) of 2-aminoethanol (Kanto Chemical special grade) A copper plate was added, and the mixture was heated and stirred for 2 hours on a hot stirrer adjusted to 170 ° C. in the atmosphere, and then allowed to cool naturally. Thereafter, the copper plate was taken out and the surface was washed with methanol.

  The color of the copper plate changed to silver by the above treatment. FIG. 31 shows (a) a scanning electron microscope image and (b) Ni element mapping image and (c) Cu element mapping image of the same field of view on the copper plate surface after the above treatment. In the scanning electron microscope image, it was observed that the surface of the copper plate was covered with the layer generated by the above treatment, and granular precipitates were partially attached. Further, from the element mapping image, it was observed that Ni was distributed substantially uniformly on the surface of the copper plate. Furthermore, since the copper plate which performed the said process adsorb | sucked to the magnet, it was guessed that the copper plate surface was coat | covered with metal Ni by the said process.

  As shown in the results of this example, when the metal oxalate is decomposed by the method of the present invention, by interposing the surface of a predetermined substance, the metal generated by the decomposition can be deposited on the surface. It is possible to coat the surface of the substance.

Claims (11)

  A method for decomposing oxalate, comprising a thermal decomposition step of heating and decomposing a mixture containing an oxalate having a coordination polymer structure and an amine having a primary amino group.   In the thermal decomposition step, a mixture of an oxalate having a coordination polymer structure and an amine having a primary amino group is heated to a first temperature to form a complex compound containing the oxalate and the amine. The method for decomposing oxalate according to claim 1, comprising a step and a second step of decomposing the complex compound by heating to a second temperature higher than the first temperature.   The oxalate decomposition method according to claim 1 or 2, wherein at least a part of the thermal decomposition step is performed in an inert gas atmosphere.   The oxalate salt according to any one of claims 1 to 3, wherein the amine having the primary amino group is an amine further having at least one other substituent exhibiting electron donating properties. Disassembly method.   The oxalate salt according to claim 4, wherein the electron-donating substituent is at least one selected from a primary to tertiary amino group, a hydroxyl group, an alkoxyl group, a carboxyl group, and a phenyl group. Disassembly method.   The oxalate decomposition method according to claim 1, wherein the oxalate having the coordination polymer structure is an oxalate of a first transition metal.   The method for decomposing oxalate according to claim 6, wherein the first transition metal is at least one metal selected from V, Cr, Mn, Fe, Co, Ni, Cu and Zn. .   A complex compound comprising an oxalate of a transition metal and an amine having a primary amino group.   The complex compound according to claim 8, wherein the transition metal is a first transition metal.   The complex compound according to claim 9, wherein the first transition metal is at least one metal selected from V, Cr, Mn, Fe, Co, Ni, Cu, and Zn.   The complex compound according to any one of claims 8 to 10, wherein the amine having the primary amino group is an amine having another substituent which further exhibits an electron donating property.