Method for producing cyanide, method for using metal oxide catalysts, and method for recovering metals

Abstract

This invention provides a method for producing cyanide that can be manufactured at room temperature, a method for using a metal oxide catalyst in the manufacturing process, and a method for recovering metal using the manufacturing method. [Solution] General formula (1): JPEG2026079578000011.jpg4269 (R in equation (1)) 1 , R 2 and R 3 Each of these is independently a hydrogen atom or a monovalent organic group which may have a substituent. A method for producing cyanide, comprising the steps of: preparing a solution by dissolving compound (A) represented by in an aqueous solvent; and preparing a mixed suspension by adding a metal oxide catalyst to the solution under oxygen-free conditions, thereby oxidizing compound (A) to produce cyanide.

Description

[Technical Field]

[0001] This disclosure relates to a method for producing cyanide. Furthermore, this disclosure relates to a method for utilizing a metal oxide catalyst and a method for recovering the metal. [Background technology]

[0002] Cyanides are essential chemicals in the modern chemical industry as raw materials for synthesizing polymer precursors and organic compounds containing useful nitrile functional groups (R-CN, where R represents an organic group such as a carbon-containing chain). Furthermore, cyanide compounds are widely used in mining processes to extract high-purity precious metals such as gold and silver. For these reasons, the cyanide market is expected to grow even further in the future. Industrial production of cyanide is carried out by methods such as the Andrewseau process, in which pressurized methane and ammonia are oxidized with oxygen at high temperatures of over 1000°C in the presence of a platinum catalyst (Non-Patent Literature 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] EP. Randviir, CE Banks, Trends in analytical chemistry, 2015, 64, 75-85 [Overview of the project] [Problems that the invention aims to solve]

[0004] The method described in Non-Patent Document 1 involves a high-temperature process exceeding 1000°C, and there is a need for a cyanide synthesis method that can reduce the environmental impact. This disclosure aims to provide an innovative method for producing cyanide that can be manufactured at room temperature. It also aims to provide a method for using a metal oxide catalyst in the production of the cyanide, and a method for recovering metal using the cyanide production method.

Means for Solving the Problem

[0005] [1]: General formula (1):

Chem.

Chem.

Chem.

Advantages of the Invention

[0006] According to the present disclosure, there is an excellent effect that an innovative method for producing a cyanide that can be produced even at room temperature can be provided. Further, there is an excellent effect that a method for using a metal oxide catalyst used in the production of the cyanide and a method for recovering a metal using the method for producing the cyanide can be provided.

Brief Description of the Drawings

[0007] [Figure 1] A flowchart showing a method for producing a cyanide according to the present embodiment. [Figure 2] Example 1: A graph plotting the concentrations of raw materials and products against reaction time. [Figure 3] Example 2: A GDMS chart of a cyanide obtained using isotopic glycine. [Figure 4] A graph plotting the yield and selectivity of a cyanide against the concentration of glycine.

Modes for Carrying Out the Invention

[0008] The present disclosure will be described in detail below. The embodiments described below illustrate examples of the present disclosure and include modifications that do not alter the essence of the disclosure. In this specification, the numbers indicated before and after "~" include lower and upper limits. Unless otherwise noted, each component can be used independently, either alone or in combination of two or more. When two or more are used in combination, the total content is used. Furthermore, the numerical values ​​specified herein are values ​​obtained by the methods described herein.

[0009] 1. Method for producing cyanide The method for producing cyanide according to this embodiment, as shown in Figure 1, comprises the steps of (a) preparing a solution by dissolving compound (A), described later, in an aqueous solvent, and (b) preparing a mixed suspension by adding a metal oxide catalyst to the solution under oxygen-free conditions, thereby oxidizing compound (A) to produce cyanide. In this specification, cyanide includes cyanide ions, HCN (hydrogen cyanide), and metal salts of cyanide ions.

[0010] Compound (A) is represented by the following general formula (1). [ka] R in general formula (1) 1 , R 2 and R 3 Each of these is independently a monovalent organic group which may have a hydrogen atom or a substituent. Here, an organic group means a hydrocarbon group which may contain at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur.

[0011] According to the cyanide production method of this embodiment, cyanide can be easily produced by contacting a compound (A) having a carbon atom in which a carboxyl group and an amino group are directly linked with a metal oxide catalyst under oxygen-free conditions. The mechanism by which compound (A) is oxidized by the metal oxide catalyst under oxygen-free conditions is speculative, but via an imine, at the carbon atom in which the carboxyl group and amino group are directly linked, R 1 , R2 It is believed that cleavage occurs. This is supported by the detection of ketocarboxylic acid derivative compounds in this manufacturing process.

[0012] As a result of repeated investigations by the present inventors, it was found that mixing a water-miscible aprotic non-reducing organic solvent, such as acetonitrile, with water increases the yield of cyanide. This suggests that adding the solvent to water has the effect of suppressing the hydrolysis of imines and promoting oxidation.

[0013] The cyanide production method of this embodiment allows for simple production over a wide temperature range. From the viewpoint of reducing environmental impact, production at room temperature and atmospheric pressure is preferable. Another advantage is that the production rate can be adjusted by temperature. For example, in applications where it is desirable to suppress the production rate of cyanide, it is possible to produce it at a temperature lower than room temperature. Furthermore, according to the cyanide production method of this embodiment, the amount of cyanide produced can be adjusted by adjusting the amount of compound (A) and metal oxide catalyst added. For this reason, the cyanide production method of this embodiment can be applied to applications that require the efficient production of large quantities of cyanide. It is also suitable for applications that require the production of low concentrations of cyanide, such as a few μM. Moreover, since ammonia can be obtained as a byproduct according to the cyanide production method of this embodiment, there is also the advantage that ammonia can be recovered and effectively utilized. Steps (a) and (b) will be described in detail below.

[0014] 1-1. Process (a) Step (a), as described above, is the step of preparing a solution by dissolving compound (A) in an aqueous solvent, thereby obtaining a solution (B) in which at least a portion of compound (A) is dissolved. Here, "dissolved" is not limited to compound (A) being completely dissolved, but includes at least a portion of compound (A) being dissolved in the aqueous solvent. Furthermore, the aqueous solvent refers to water, or a mixture of water and another solvent.

[0015] In the case of the aforementioned mixture, water is included. From a cost standpoint, using water is advantageous, and from the viewpoint of increasing the yield of cyanide, a mixture of a water-miscible aprotic non-reducing organic solvent and water is preferred. The water content in the solvent can be, for example, 30% or more by mass, 50% or more by mass, 70% or more by mass, 80% or more by mass, 90% or more by mass, or 100% by mass, based on 100% by mass of the solvent.

[0016] Other solvents should be water-compatible. Preferably, the other solvents are aprotic, non-reducing organic solvents, such as acetonitrile, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, dimethylformamide, 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone, 1,4-dioxane, and hexamethylphosphoramide. The other solvents may be used alone or in combination.

[0017] Compound (A) is represented by the following general formula (1), as described above. [ka] R in general formula (1) 1 , R 2 and R 3 Each of these is independently a monovalent organic group which may have a hydrogen atom or a substituent. Here, an organic group means a hydrocarbon group which may contain at least one heteroatom selected from the group consisting of nitrogen, oxygen, and sulfur. Examples of hydrocarbon groups include linear hydrocarbon groups, alicyclic hydrocarbon groups, aromatic hydrocarbon groups, and any combination thereof. Substituents can be various functional groups. Specific examples of substituents include carboxyl groups, hydroxyl groups, thiol groups, halogens, amino groups, sulfo groups, phosphate groups, sulfonamide groups, phenyl groups, phthalimide alkyl groups, alkoxy groups with 1 to 10 carbon atoms, and alkoxycarbonyl groups with 1 to 10 carbon atoms.

[0018] A chain-like hydrocarbon group refers to a hydrocarbon group composed solely of a chain-like structure. The chain-like structure may be linear or branched. The number of carbon atoms in the chain-like hydrocarbon group is preferably 1 to 12, more preferably 1 to 6, and even more preferably 1 to 4. Suitable examples of chain-like hydrocarbon groups include alkyl, alkenyl, and alkynyl groups. These may be linear or branched, and may have substituents. Preferred alkyl groups include methyl, ethyl, n-propyl, i-propyl, n-butyl, s-butyl, isobutyl, t-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and dodecyl. Preferred alkenyl groups include vinyl, propenyl, and n-butenyl. Preferred alkynyl groups include ethynyl, propynyl, and n-butynyl. Among these, alkyl groups which may have a carboxyl group or a hydroxyl group are preferred.

[0019] An alicyclic hydrocarbon group is a hydrocarbon group that contains an alicyclic hydrocarbon as its ring structure but does not contain an aromatic ring. The alicyclic hydrocarbon may be monocyclic or polycyclic. It may also have a fused ring. The number of carbon atoms in the alicyclic hydrocarbon group is preferably 3 to 12, more preferably 3 to 6, and even more preferably 5 or 6. Specific examples of alicyclic hydrocarbon groups include cycloalkyl, cycloalkenyl, and cycloalkynyl groups. Examples of cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl. Specific examples of cycloalkenyl groups include cyclopropenyl, cyclobutenyl, cyclopentenyl, and cyclohexenyl. Specific examples of cycloalkynyl groups include cyclopropynyl, cyclobutynyl, cyclopentynyl, and cyclohexynyl. Among these, cycloalkyl groups, which may have a carboxyl group or a hydroxyl group, are preferred.

[0020] An aromatic hydrocarbon group is a hydrocarbon group that contains an aromatic ring structure. The aromatic ring may be monocyclic or polycyclic. It may also have a fused ring. Aryl groups are preferred as aromatic hydrocarbon groups. The number of carbon atoms in the aromatic hydrocarbon group is preferably 6 to 12, more preferably 6 to 10, and even more preferably 6. Specific examples of aromatic hydrocarbon groups include phenyl and naphthyl. Phenyl is preferred as the aromatic hydrocarbon group.

[0021] Among the hydrocarbon groups mentioned above, alkyl, cycloalkyl, aryl, and combinations thereof are preferred as hydrocarbon groups.

[0022] A preferred example of compound (A) is the R in general formula (1). 1 is a hydrogen atom, and the R 2 and R 3 Each of these independently contains a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms, which may have substituents. Among these, compound (A) is R 1 is a hydrogen atom, and the R 2 is a hydrogen atom, or a hydrocarbon group having 1 to 12 carbon atoms which may have substituents, and the R 3 A C1-C6 alkyl group is more preferable. Even more preferably, R 3 The substituents are methyl, ethyl, propyl, and butyl groups. Preferred examples of substituents include carboxyl, hydroxyl, indole, hydroxyphenyl, and imidazole.

[0023] Specific examples of compound (A) include glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, cystine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine and histidine, and N-methylglycine. Oligopeptides formed from 1 to 5 glycine molecules are also preferred. Compound (A) can be used alone or in combination of two or more.

[0024] The pH of solution (B) obtained by step (a) is not particularly limited. It can be adjusted to a wide range of pH from 1 to 14 depending on the application. pH adjusters can be added to solution (B) as optional components to obtain the desired pH. Examples of pH adjusters include ammonia; inorganic acids such as hydrochloric acid and phosphoric acid; organic acids such as acetic acid, lactic acid, glycolic acid, succinic acid, tartaric acid, dl-malic acid and citric acid; alkali hydroxides such as lithium hydroxide, sodium hydroxide, potassium hydroxide, potassium carbonate, sodium carbonate, sodium bicarbonate, potassium dihydrogen phosphate and disodium hydrogen phosphate; and organic amines such as triethylamine, triethanolamine, diethanolamine and triisopropanolamine. Other components may be added to solution (B) without departing from the spirit of this disclosure.

[0025] When extracting cyanide as hydrogen cyanide gas in a one-pot process, the solution (B) is preferably acidic, and can be adjusted to a pH of 1 to 6, for example. From the viewpoint of increasing the efficiency of hydrogen cyanide gas production, a pH of 1 to 4 is more preferable, and a pH of 1 to 2 is even more preferable. On the other hand, when the target product is a cyanide salt, a pH of 7 to 14 is preferred, more preferably a pH of 9 to 13, and even more preferably a pH of 12 to 13.

[0026] The concentration in step (a) should be such that at least a portion of compound (A) is dissolved, and can be adjusted according to the type of compound (A) and aqueous solvent. Alternatively, it should be designed to a concentration suitable for the production of cyanide. For example, it can be 0.01 to 0.1 mol / L.

[0027] 1-2. Process (b) Step (b), as described above, is a step in which a mixed suspension is prepared by adding a metal oxide catalyst to the solution under oxygen-free conditions, and compound (A) is oxidized to produce cyanide. The metal oxide catalyst is added to solution (B) from step (a) to obtain mixed suspension (C). Oxygen-free conditions are synonymous with the absence of oxygen gas. Since the oxidation reaction of compound (A) would be stopped by oxygen gas, step (b) must be carried out under oxygen-free conditions.

[0028] The mixed suspension (C) is degassed. Degassing may be performed at step (a) instead of, or in combination with, the degassing method at this stage. Alternatively, the aqueous solution and compound (A) may be degassed separately before obtaining solution (B), and the metal oxide catalyst may be degassed before being added to solution (B) in step (b). Step (b) is preferably carried out under an inert gas atmosphere such as nitrogen gas or argon.

[0029] Once the mixed suspension (C) is sufficiently degassed and under oxygen-free conditions, compound (A) is oxidized by the metal oxide catalyst, producing cyanide. If the mixed suspension (C) is acidic, hydrogen cyanide (HCN) gas is produced. High-purity cyanide can be obtained by recovering this HCN gas. If the mixed suspension (C) is neutral or alkaline, the HCN gas can be recovered by adjusting the mixed suspension (C) to an acidic state after the reaction is complete.

[0030] The metal oxides in the mixed suspension (C) after the reaction dissolve to form metal ions. These metal ions can be converted back into metal oxides by calcination in air or hydrothermal treatment. These recycled metal oxides can then be used as catalysts for new reactions.

[0031] The temperature in step (b) should be such that at least a portion of compound (A) is dissolved, and should be appropriately selected depending on the type of compound (A) and aqueous solvent. As long as the above conditions are met, the temperature is not limited and can be selected from a wide range, from low temperatures such as -20°C to high temperatures such as 300°C. From the viewpoint of reaction efficiency, heating is preferred, and from the viewpoint of reducing environmental impact, temperatures near room temperature are preferred. In addition, to control the rate of cyanide formation, low temperatures such as 0 to 10°C may be used. The method for producing cyanide according to this disclosure allows for the production of cyanide over a wide temperature range. Since the rate of cyanide production can be adjusted by controlling the temperature, it can be used for a variety of applications.

[0032] A metal oxide catalyst is a catalyst containing a metal oxide. A metal oxide is a compound composed of one or more transition metal elements and oxygen atoms in any ratio. Preferred metals include elements with atomic numbers 21 to 30. Specific examples of metal oxide catalysts include silica, alumina, zirconia, titania, tungsten oxide, magnesium oxide (magnesia), vanadium oxide, chromium oxide, manganese oxide, iron oxide, nickel oxide, cobalt oxide, copper oxide, zinc oxide, molybdenum oxide, tin oxide, calcium oxide, boron oxide (boria), zeolite, or mixtures thereof. Metal oxide catalysts may also be composite metal oxides. Examples include silica-alumina, silica-magnesia, silica-boria, alumina-boria, silica-titania, silica-zirconia, zinc oxide-zirconia, and molecular sieves. Metal oxide catalysts can be used individually or in combination of two or more types.

[0033] Among these, manganese oxide, copper oxide, and cuprous oxide are preferred from the viewpoint of conversion efficiency. Examples of manganese oxide include α-manganese dioxide, β-manganese dioxide, and γ-manganese dioxide. Among these, α-manganese dioxide and γ-manganese dioxide are more preferred, and γ-manganese dioxide is even more preferred.

[0034] The method for recovering the cyanide generated in step (b) is not particularly limited. It can be recovered by known methods. From the viewpoint of ease of separation, a simple method is to recover hydrogen cyanide gas by making the mixed suspension (C) acidic. Alternatively, the metal oxide catalyst can be recovered from the mixed suspension (C), and the mixed suspension (C) itself can be used as a liquid containing cyanide.

[0035] 2. Methods for using metal oxide catalysts The method of using the metal oxide catalyst in this embodiment is based on the general formula (1): [ka] (R in general formula (1)) 1 , R 2 and R 3Each of these is independently a hydrogen atom or a monovalent organic group which may have a substituent. This invention relates to a method for producing cyanide from compound (A) by adding a metal oxide catalyst under oxygen-free conditions to an aqueous solvent in which compound (A) is dissolved. Parts common to "1. Method for Producing Cyanide" are referenced from "1. Method for Producing Cyanide".

[0036] According to the method of using the metal oxide catalyst in this embodiment, the amount of cyanide produced can be controlled by adjusting the amount of metal oxide catalyst added to compound (A). By adding a sufficient amount of metal oxide catalyst to compound (A), cyanide can be produced efficiently in a short time. On the other hand, by adding the metal oxide catalyst to compound (A) in an amount that results in a desired amount of cyanide production, the desired amount of cyanide can be produced at a desired timing. In addition to the amount added, the amount and rate of cyanide production can be controlled by changing the type of metal oxide catalyst, particle size, BET specific surface area, etc.

[0037] Metal oxide catalysts can be recovered by reprecipitation of soluble metal ions after the reaction. After recovery, the metal oxide catalyst can be recycled by calcination, hydrothermal treatment, etc.

[0038] This disclosure also relates to a catalyst composition for cyanide production, comprising at least one metal oxide. This catalyst composition for cyanide production is used for the production of cyanide from compound (A) (e.g., glycine). That is, this catalyst composition for cyanide production is a composition used for the production of the cyanide described above. The metal oxide used in this composition is as described above. The metal oxide can be selected from, for example, oxides of transition metals. A preferred example is an oxide of manganese. This catalyst composition for cyanide production is a composition that is suitable for use in step (b) of the cyanide production of this disclosure, and may be a liquid (suspension, dispersion, solution, etc.) or a solid (powder, etc.). This catalyst composition for cyanide production may contain one or more optional components, without departing from the spirit of this disclosure. Examples of such optional components include components that promote the production of cyanide from compound (A), metal oxide dispersion stabilizers, pH adjusters, etc.

[0039] 3. Methods for recovering metal The metal recovery method of this embodiment involves using an aqueous solvent containing the general formula (1): [ka] (R in general formula (1)) 1 , R 2 and R 3 Each of these is independently a hydrogen atom or a monovalent organic group which may have a substituent. Compound (A) represented by is dissolved, a metal oxide catalyst is added under oxygen-free conditions to obtain a mixed suspension, and compound (A) is oxidized by the metal oxide catalyst to generate cyanide. A metal-containing ore is leached into the mixed suspension containing the cyanide. A metal-rich leachate and residue are produced from the aforementioned metal-containing ore. This invention relates to a method for recovering metals from metal-containing ore, which includes a step of separating the metal-rich leachate from the residue. Parts common to "1. Method for Producing Cyanide" are based on the description in "1. Method for Producing Cyanide."

[0040] In this embodiment, the mixed suspension is made alkaline so that cyanide contained in the mixed suspension does not generate as a gas. The pH is, for example, 7 to 14, more preferably 9 to 13, and even more preferably 12 to 13. Examples of recovered metals include gold, silver, platinum, copper, and other rare metals.

[0041] According to the metal recovery method of this embodiment, useful metals can be recovered with high efficiency by immersing metal-containing ore in a mixed suspension containing cyanide, which is obtained by oxidizing compound (A) with a metal oxide catalyst under oxygen-free conditions. Since cyanide can be produced at room temperature, energy consumption can be significantly reduced.

[0042] 4. Other uses The method for producing cyanide according to this disclosure can be easily carried out at room temperature and atmospheric pressure, and therefore can be applied to various uses in addition to the metal recovery applications described above. For example, according to the method according to this disclosure, hydrogen cyanide gas can be obtained by adding a metal oxide catalyst at a desired timing at room temperature and atmospheric pressure, making it suitable for pest control applications. Also, for the same reason, it is suitable for disinfection (fungal and insect repellent) of grains, seeds, articles, etc. Furthermore, the cyanide obtained by the method for producing cyanide according to this disclosure can be suitably used as a raw material for various organic compounds containing cyano groups. [Examples]

[0043] The present disclosure will be further illustrated by examples. The present disclosure is not limited thereto. In the examples, “parts” means “parts by mass” and “%” means “percent mass”.

[0044] (Example 1) To 50 mL of purified water, 187 mg of glycine and 200 mg of sodium hydroxide were added to prepare a solution containing 50 mM glycine and 0.1 M sodium hydroxide. The pH of this solution was 12.6. Next, 1000 mg of manganese dioxide (Fujifilm) was added to this solution to prepare a mixed suspension. 2.5 mL of this mixed suspension was then sealed in an airtight varial filled with argon (96%) and hydrogen gas (4%). After incubation at room temperature (25°C) for 24 hours, NaCN, a cyanide, was obtained (yield: 1.18 ± 0.01 mM). The cyanide yield was quantified by ultra-high-performance liquid chromatography (UPLC) after derivatization to a fluorescent molecule according to previously reported optimal buffer conditions.

[0045] Figure 2 shows a plot of the concentrations of the starting material (glycine) and products (cyanide and ammonia) from the start of the reaction. As shown in Figure 2, it was confirmed that cyanide was formed within 1 minute after mixing glycine and manganese dioxide. The cyanide concentration increased with reaction time, and it was confirmed that the reaction was almost complete after 9 hours. In contrast, the glycine concentration was confirmed to decrease continuously. Furthermore, it was confirmed that ammonia as a byproduct increased continuously. It is thought that cyanide was formed according to the following scheme. CH2-NH2-COO - +MnO2+6OH - →CN - +CO3 2- +5H2O The concentration was measured using high-pressure liquid chromatography (HPLC).

[0046] (Example 2) An isotope experiment was conducted to confirm that cyanide is produced from glycine. Specifically, ordinary glycine, which is not isotope-labeled, was used as the glycine. 12 1C-glycine) and glycine (1C-glycine) in which the carbon atom of the carboxyl group of glycine is isotoped. 13 1C-glycine), glycine (2C-glycine) isotopically labeled with the α-carbon (the carbon atom directly bonded to the nitrogen atom and carboxyl group) of glycine. 13The experiment was carried out in the same manner as in Example 1, except that C-glycine was used, to obtain cyanide. Figure 3 shows the results of gas chromatography-mass spectroscopy (GCMS) analysis of the products from the three glycine-based examples. As shown in the figure, 2C- 13 When 13C-glycine was used, hydrogen cyanide derived from 13C was produced, and it was confirmed that the cyanide was derived from glycine. Furthermore, when a similar experiment was conducted using deuterated glycine, the rate of cyanide formation was reduced to approximately one-quarter. This suggests that the oxidative dehydrogenation reaction of the CH bond is the rate-determining step.

[0047] (Example 3) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with alanine (yield: 2.37 ± 0.88 μM).

[0048] (Example 4) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with glutamic acid (yield: 3.33 ± 0.07 μM).

[0049] (Example 5) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with aspartic acid (yield: 0.07 ± 0.004 mM).

[0050] (Example 6) Cyanide was obtained using the same method as in Example 1, except that glycine was replaced with tyrosine (yield: 0.035 ± 0.002 mM).

[0051] (Example 7) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with N-methylglycine (yield: 0.049 ± 0.01 mM).

[0052] (Example 8) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with leucine (yield: 1.23 ± 0.01 μM).

[0053] (Example 9) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with phenylalanine (yield: 2.4 ± 0.3 μM).

[0054] (Example 10) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with asparagine (yield: 24.9 ± 0.6 μM).

[0055] (Example 11) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with glutamine (yield: 1.9 ± 0.2 μM).

[0056] (Example 12) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with isoleucine (yield: 2.5 ± 1.2 μM).

[0057] (Example 13) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with serine (yield: 3.0 ± 1.1 μM).

[0058] (Example 14) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with threonine (yield: 0.06 ± 0.003 mM).

[0059] (Example 15) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with valine (yield: 1.2 ± 0.06 μM).

[0060] (Example 16) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with tryptophan (yield: 23.4 ± 0.1 μM).

[0061] (Example 17) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with proline (yield: 0.79 ± 0.2 μM).

[0062] (Example 18) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with arginine (yield: 5.7 ± 0.4 μM).

[0063] (Example 19) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with histidine (yield: 0.09 ± 0.004 mM).

[0064] (Example 20) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with methionine (yield: 2.3 ± 0.2 μM).

[0065] (Example 21) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with cysteine ​​(yield: 1.4 ± 0.05 μM).

[0066] (Example 22) Cyanide was obtained in the same manner as in Example 1, except that glycine was replaced with glycine tripeptide (yield: 0.60 ± 0.01 mM).

[0067] (Comparative Example 1) Cyanide was not obtained using the same method as in Example 1, except that glycine was replaced with beta-alanine.

[0068] (Comparative Example 2) Cyanide was not obtained by the same method as in Example 1, except that glycine was replaced with γ-aminobutyric acid.

[0069] (Example 23) Cyanide was obtained in the same manner as in Example 1, except that the manganese dioxide used in Example 1 was replaced with copper oxide (0.42 ± 0.04 μM).

[0070] (Example 24) Cyanide was obtained in the same manner as in Example 1, except that the manganese dioxide used in Example 1 was replaced with cuprous oxide (yield: 2.11 ± 0.04 μM).

[0071] (Example 25) Cyanide was obtained in the same manner as in Example 1, except that the manganese dioxide used in Example 1 was replaced with copper hydroxide (yield: 2.14 ± 0.03 μM).

[0072] (Example 26) Cyanide was obtained in the same manner as in Example 1, except that the temperature used in Example 1 (25°C) was changed to 60°C (yield: 1.7 ± 0.05 μM).

[0073] (Example 27) Cyanide was obtained in the same manner as in Example 1, except that the temperature used in Example 1 (25°C) was changed to 6°C (yield: 1.48 ± 0.02 μM).

[0074] (Example 28) Cyanide was obtained using the same method as in Example 1, except that the temperature (25°C) used in Example 1 was changed to 40°C (yield: 0.72 ± 0.01 mM).

[0075] (Example 29) Cyanide was obtained in the same manner as in Example 1, except that the pH (12.6) used in Example 1 was changed to 2 (yield: 0.08 ± 0.03 mM).

[0076] (Example 30) Cyanide was obtained in the same manner as in Example 1, except that the pH (12.6) used in Example 1 was changed to 5.8 (yield: 0.05 ± 0.01 mM).

[0077] (Example 31) Cyanide was obtained in the same manner as in Example 1, except that the pH (12.6) used in Example 1 was changed to 9.2 (yield: 0.02 ± 0.005 mM).

[0078] (Example 32) Figure 4 shows the results of investigating the amount of cyanide produced and the cyanide selectivity of the product by changing the glycine concentration in the composition of Example 1. As shown in Figure 4, it was confirmed that lower glycine concentrations resulted in higher cyanide selectivity in the product.

Claims

1. General formula (1): 【Chemistry 1】 (R in equation (1)) １ , R ２ and R ３ Each of these is independently a hydrogen atom or a monovalent organic group which may have a substituent. A step of preparing a solution by dissolving compound (A) represented by in an aqueous solvent, and A step of preparing a mixed suspension by adding a metal oxide catalyst to the solution under oxygen-free conditions, and oxidizing compound (A) to produce cyanide, A method for producing cyanide having the following characteristics.

2. The aforementioned R １ is a hydrogen atom, and the R ２ and R ３ The method for producing cyanide according to claim 1, wherein each is independently a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may have substituents.

3. General formula (1): 【Chemistry 2】 (In formula (1), R １ , R ２ and R ３ are each independently a hydrogen atom or a monovalent organic group which may have a substituent.) A method for using a metal oxide catalyst, comprising adding a metal oxide catalyst to an aqueous solvent in which compound (A) represented by [formula] is dissolved, under oxygen-free conditions, to produce cyanide from compound (A).

4. The aforementioned R １ is a hydrogen atom, and the R ２ and R ３ The method for using a metal oxide catalyst according to claim 3, wherein each is independently a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may have substituents.

5. For aqueous solvents, the general formula (1): 【Transformation 3】 (R in equation (1)) １ , R ２ and R ３ Each of these is independently a hydrogen atom or a monovalent organic group which may have a substituent. Compound (A) represented by is dissolved, a metal oxide catalyst is added under oxygen-free conditions to obtain a mixed suspension, and compound (A) is oxidized by the metal oxide catalyst to generate cyanide. A metal-containing ore is leached into the mixed suspension containing the cyanide. A metal-rich leachate and residue are produced from the aforementioned metal-containing ore. A method for recovering metal from metal-containing ore, comprising the step of separating the metal-rich leachate from the residue.

6. The aforementioned R １ is a hydrogen atom, and the R ２ and R ３ The method for recovering a metal according to claim 5, wherein each is independently a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms which may have substituents.

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