Method for preparing benzene hexathiol

Abstract

To synthesize hexabenzenethiol more easily, and form larger benzenehexathiol nanosheets.SOLUTION: 4-methoxy-α-toluenethiol is reacted with hexafluorobenzene to synthesize hexakis(4-methoxybenzylthio)benzene, the synthesized hexakis(4-methoxybenzylthio)benzene is dissolved in trifluoroacetic acid to be heated, resulting in the synthesis of benzenehexathiol. In a state where a thin film of aqueous solution is formed on a substrate surface, the substrate surface is supplied with a base material solution with benzenehexathiol dissolved therein, thereby forming a film composed of the base material solution on the substrate surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a method for producing benzenehexathiol. In the law To relate to. [Background technology]

[0002] Two-dimensional nanosheet-like complexes composed of hexabenzenethiol and metal are expected to function as topological insulators. Conventional and generally known methods for synthesizing benzenehexathiol use hexachlorobenzene and benzyl mercaptan. In this synthesis method, the benzyl group is removed using metallic sodium in liquid ammonia cooled to -78°C (Figure 4).

[0003] Furthermore, two-dimensional nanosheet-like complexes composed of benzenehexathiol and metal are formed at the liquid-phase interface (see Non-Patent Literature 2). In this technique, benzenehexathiol nanosheets are formed at the interface between an aqueous layer containing a dissolved metal salt and an organic layer containing a dissolved ligand. Nanosheets are formed by bringing an aqueous solution containing dissolved metal ions into contact with an organic solution containing dissolved benzenehexathiol, and generating nanosheets at this interface (liquid-liquid interface method). By reducing the amount of organic solution used, nanosheets are generated on the surface of the aqueous solution as it evaporates (gas-liquid interface method). After forming the nanosheets in this way, the generated nanosheets are transferred to a substrate. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] Jennifer A. Harnisch and Robert J. Angelici, "Gold and platinum benzenehexathiolate complexes as large templates for the synthesis of 12-coordinate polyphosphine macrocycles", Inorganica Chimica Acta, vol. 300.302, pp. 273-279, 2000. [Non-Patent Document 2] T. Kambe et al., "π-Conjugated Nickel Bis(dithiolene) Complex Nanosheet", Journal of the American Chemical Society, vol. 135, no. 7, pp. 2462-2465, 2013. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] However, conventional methods for synthesizing hexabenzenethiol use liquid ammonia and metallic sodium, which makes handling the chemicals difficult and hinders easy synthesis. Furthermore, conventional nanosheet formation techniques form nanosheets at the interface between the aqueous and organic layers, requiring transfer to a specific substrate. Therefore, conventional techniques have the problem of not easily obtaining large-area nanosheets.

[0006] This invention was made to solve the above-mentioned problems and aims to facilitate the synthesis of hexabenzenethiol. It also aims to enable the formation of larger benzenehexathiol nanosheets. [Means for solving the problem]

[0007] The present invention provides a method for producing benzenehexathiol, comprising: a first step of reacting toluenethiol having at least one methoxy group with any of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene to produce a compound; and a second step of dissolving the compound in trifluoroacetic acid and heating it to remove the methoxybenzyl group from the compound and produce benzenehexathiol.

[0008] Furthermore, the method for producing nanosheets according to the present invention comprises: a first step of preparing a raw material solution in which benzenehexathiol is dissolved in a water-soluble organic solvent; a second step of supplying the raw material solution to the surface of a substrate while a thin film of aqueous solution is formed on the surface of the substrate, thereby forming a film of the raw material solution on the surface of the substrate; and a third step of removing the aqueous solution from the surface of the substrate to remove the organic solvent from the film of the raw material solution, thereby separating benzenehexathiol from the raw material solution and forming a sheet of benzenehexathiol on the surface of the substrate. [Effects of the Invention]

[0009] As described above, according to the present invention, benzenehexathiol can be synthesized more easily by reacting toluenethiol having a methoxy group with any of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene, dissolving the resulting compound in trifluoroacetic acid, and heating it. Furthermore, according to the present invention, a thin film of aqueous solution is formed on the surface of the substrate, and then the raw material solution is supplied to the surface of the substrate to form a film of the raw material solution on the surface of the substrate, thus enabling the formation of larger benzenehexathiol nanosheets. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a flowchart illustrating a method for producing benzenehexathiol according to an embodiment of the present invention. [Figure 2]Figure 2 is an explanatory diagram showing the chemical reaction equation for the synthesis of hexakis(4-methoxybenzylthio)benzene by the reaction of 4-methoxy-α-toluenethiol with hexafluorobenzene. [Figure 3] Figure 3 is an explanatory diagram showing the chemical reaction equation for the synthesis of benzenehexathiol by removing the methoxybenzyl group from hexakis(4-methoxybenzylthio)benzene. [Figure 4] Figure 4 is a flowchart illustrating a method for producing nanosheets according to an embodiment of the present invention. [Figure 5] Figure 5 is an explanatory diagram showing the chemical reaction equation for the synthesis of benzene hexathiol as presented in Non-Patent Document 1. [Modes for carrying out the invention]

[0011] The following describes a method for producing benzenehexathiol according to an embodiment of the present invention, with reference to Figure 1. First, in the first step S101, a toluenethiol having at least one methoxy group is reacted with one of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene to produce a compound (first step). For example, hexakis(4-methoxybenzylthio)benzene is synthesized as a compound by reacting 4-methoxy-α-toluenethiol with hexafluorobenzene (aromatic nucleophilic substitution reaction). This synthesis can be carried out in a solvent to which a base has been added. For example, a solvent to which sodium hydroxide has been added can be used. 1,3-dimethyl-2-imidazolidinone can be used as this solvent. As the reaction proceeds, hexakis(4-methoxybenzylthio)benzene precipitates. Figure 2 shows the reaction equation.

[0012] Next, in the second step S102, the synthesized compound [hexakis(4-methoxybenzylthio)benzene] is dissolved in trifluoroacetic acid [CF3COOH] and heated to eliminate the methoxybenzyl group from the compound [hexakis(4-methoxybenzylthio)benzene] (deprotection reaction of the SH group used as a protecting group) to produce (synthesize) benzenehexathiol (second step). This production (second step) can be carried out by heating trifluoroacetic acid to 70 °C. Also, in this production (second step), the compound [hexakis(4-methoxybenzylthio)benzene] can be dissolved in trifluoroacetic acid in which triethylsilane [(C2H5)3SiH] is dissolved. The reaction formula is shown in FIG. 3.

[0013] As described above, once benzenehexathiol is produced, in the third step S103, by removing the trifluoroacetic acid used as a solvent, benzenehexathiol can be obtained.

[0014] Next, a method for producing nanosheets using benzenehexathiol will be described with reference to FIG. 4.

[0015] First, in the first step S111, a raw material solution in which benzenehexathiol is dissolved in a water-soluble organic solvent is prepared.

[0016] Next, in the second step S112, with a thin film of an aqueous solution formed on the surface of the substrate, the raw material solution is supplied to the surface of the substrate to form a film of the raw material solution on the surface of the substrate. For example, by floating the substrate on the above-mentioned aqueous solution contained in a container, a thin film of the aqueous in the second step S112, with a thin film of an aqueous solution formed on the surface of the substrate, the raw material solution is supplied to the surface of the substrate to form a film of the raw material solution on the surface of the substrate. For example, by floating the substrate on the above-mentioned aqueous solution contained in a container, a thin film of the aqueous solution can be formed on the surface of the substrate.

[0017] Next, in the third step S113, by removing the aqueous solution from the surface of the substrate, the organic solvent is removed from the film of the raw material solution and benzenehexathiol is separated from the raw material solution to form a sheet of benzenehexathiol on the surface of the substrate. For example, after floating the substrate on the above-mentioned aqueous solution contained in a container, the above-mentioned aqueous solution can be discharged from the container to carry out the removal of the aqueous solution.

[0018] Next, we will explain in more detail using examples.

[0019] [Preparation of benzene hexathiol] First, we will explain the preparation of benzene hexathiol.

[0020] First, hexakis(4-methoxybenzylthio)benzene is synthesized.

[0021] NaOH (1.08 g, 27 mmol) and 1,3-dimethyl-2-imidazolidinone (32.00 mL) were placed in a Schlenk tube (50 mL). The Schlenk tube was purged with nitrogen three times, and while cooling with room temperature water, 4-methoxy-α-toluenethiol (3.30 mL, 24 mmol) was added. After stirring for 1 minute, hexafluorobenzene (0.345 mL, 3.0 mmol) was added. Cooling was continued for 10 minutes after adding hexafluorobenzene. After this, the precipitate [reaction mixture] obtained by stirring at room temperature for 2 hours was reprecipitated in methanol (approximately 200 mL) from which oxygen had been removed by bubbling nitrogen for more than 30 minutes. After reprecipitation with methanol, the precipitate was filtered off, washed with methanol, and then dried under reduced pressure to obtain hexakis(4-methoxybenzylthio)benzene (yield 2.31 g, yield 78%).

[0022] The obtained hexakis(4-methoxybenzylthio)benzene 1 H NMR spectrum measurement, and 13 The results of the 13C NMR spectrum measurement are shown. The resonance frequency was 400 MHz, and deuterated chloroform (CDCl3) was used as the solvent. The numerical values ​​after δ indicate the chemical shift, s, d, and br in parentheses indicate the peak splitting state, the J value is the coupling constant, 12H is the integrated intensity, and ArH, CH2, and OCH3 indicate the assignment of the target H atom (see Japanese Patent Publication No. 2015-172166). 13 The same applies to 13C NMR.

[0023] 11H NMR (400 MHz, CDCl3): δ 7.10 (d, J = 8.4 Hz, 12H, ArH), 6.73 (d, J = 6.8 Hz, 12H, ArH), 3.98 (s, 12H, CH2), 3.70 (s, 18H, OCH3). 13 13C NMR (400 MHz, CDCl3): δ 158.74 146.71, 130.34, 129.31, 113.69, 55.17, 41.84.

[0024] Next, synthesize benzenehexathiol. <N000119> Trifluoroacetic acid (10 mL) and triethylsilane (1.91 mL) were placed in a nitrogen-purged Schlenk tube (50 mL). Hexakis(4-methoxybenzylthio)benzene (0.20 g, 0.20 mmol) obtained as described above was added to this Schlenk tube. While stirring these, the mixture was heated from room temperature to 70 °C and reacted for 1.5 hours. Subsequently, trifluoroacetic acid was vaporized and removed by reducing the pressure in the Schlenk tube at room temperature. Next, the non-volatile liquid was removed by cannula filtration, and the white powder in the Schlenk tube was washed 4 times with chloroform and then dried under reduced pressure to obtain benzenehexathiol (yield 0.043 g, yield 79%). [[ID=X]]

[0026] The obtained benzenehexathiol 1 1H NMR spectrum measurement, 13 13C NMR spectrum measurement, and IR measurement (total reflection measurement: ATR) results are shown. The resonance frequency was 400 MHz, and pyridine-d5 (C5D5N) was used as the solvent. The values after δ indicate the chemical shift. 13 The same applies to 13C NMR.

[0027] 1HNMR (400MHz, C5D5N): δ7.19 (br, 6H, ArSH). 13CNMR(400MHz,C5D5N):δ131.35. IR(ATR):3407.6,2494.5,1680.7,1482.0,1443.5,1306.5,1276.7,1204.3,1136.8,922.8,900.6,845.6,803.2,803.2,726.1,557.3cm -1 .

[0028] [Nanosheet fabrication] Next, we will explain how to create nanosheets.

[0029] [Preparation Method 1]: Levitation Method First, a silicon wafer (substrate) was suspended in a saturated 35 mM nickel acetate-10 mM sodium bromide aqueous solution (3 mL) to form a film of the aqueous solution on the silicon wafer. Next, an ethyl acetate solution of benzenehexathiol (100-fold dilution of the saturated solution; 70 μL) was gently dropped onto the silicon wafer and allowed to stand for 4 hours. After this, the solution was drained and washed with water and ethyl acetate to obtain a nanosheet of benzenehexathiol on the silicon wafer.

[0030] [Preparation Method 2]: Levitation Method A transmission electron microscope (TEM) mesh grid (substrate) was floated in a 3 mL aqueous solution of 35 mM nickel acetate and 10 mM sodium bromide saturated with ethyl acetate, so that a film of the aqueous solution formed on the TEM mesh grid. Next, an ethyl acetate solution of benzenehexathiol (100-fold dilution of the saturated solution; 70 μL) was gently added dropwise onto the TEM mesh grid and allowed to stand for 5 hours. After this, the solution was drained and washed with water and ethyl acetate to obtain benzenehexathiol nanosheets on the TEM mesh grid.

[0031] [Preparation Method 3]: Drainage Method A 35 mM nickel acetate-10 mM sodium bromide aqueous solution saturated with ethyl acetate was placed in a designated container, and a silicon wafer (substrate) was submerged in this solution. Next, the solution in the container was drained until the silicon wafer was almost completely submerged, so that a film of the aqueous solution formed on the silicon wafer. Then, an ethyl acetate solution of benzenehexathiol (100-fold dilution of the saturated solution; 70 μL) was gently dropped onto the silicon wafer with the aqueous solution film and allowed to stand for 5 hours. After this, the solution in the container was completely drained, and the wafer was washed with water and ethyl acetate. As a result, a nanosheet of benzenehexathiol was obtained on the silicon wafer.

[0032] [Preparation Method 4]: Drainage Method A 35 mM nickel acetate-10 mM sodium bromide aqueous solution saturated with ethyl acetate was placed in a designated container, and a TEM mesh grid was submerged in this solution. Next, the solution was drained until the TEM mesh grid was almost completely covered, so that a film of the aqueous solution formed on the TEM mesh grid. Then, an ethyl acetate solution of benzenehexathiol (100-fold dilution of the saturated solution; 70 μL) was gently added dropwise onto the TEM mesh grid with the aqueous solution film, and it was allowed to stand for 3 hours. After this, the solution in the container was completely drained, and the container was washed with water and ethyl acetate. As a result, a nanosheet of benzenehexathiol was obtained on the TEM mesh grid.

[0033] As described above, according to the present invention, benzenehexathiol is synthesized by reacting toluenethiol having a methoxy group with any of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene, dissolving the resulting compound in trifluoroacetic acid, and heating it, thereby enabling the easier synthesis of hexabenzenethiol. Furthermore, according to the present invention, a thin film of aqueous solution is formed on the surface of the substrate, and the raw material solution is supplied to the surface of the substrate to form a film of the raw material solution on the surface of the substrate, thereby enabling the formation of larger benzenehexathiol nanosheets. According to the present invention, benzenehexathiol can be synthesized more safely and easily than conventional methods, and larger nanosheets can be obtained.

[0034] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0035] [Note 1] A method for producing benzenehexathiol, comprising: a first step of reacting a toluenethiol having at least one methoxy group with any of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene to produce a compound; and a second step of dissolving the compound in trifluoroacetic acid and heating it to remove the methoxybenzyl group from the compound and produce benzenehexathiol.

[0036] [Note 2] The method for producing benzenehexathiol as described in Appendix 1, characterized in that the first step involves reacting 4-methoxy-α-toluenethiol with hexafluorobenzene to synthesize hexakis(4-methoxybenzylthio)benzene as the compound.

[0037] [Note 3] A method for producing benzenehexathiol as described in Appendix 1 or 2, characterized in that the first step is carried out in a solvent to which a base has been added.

[0038] [Note 4] A method for producing benzenehexathiol as described in any one of Appendix 1 to 3, characterized in that the second step is carried out by heating trifluoroacetic acid to 70°C.

[0039] [Note 5] A method for producing benzenehexathiol as described in any one of Appendix 1 to 4, wherein the second step is characterized by dissolving the compound in trifluoroacetic acid in which triethylsilane is dissolved.

[0040] [Note 6] A method for producing benzenehexathiol as described in any one of Appendix 1 to 5, characterized in that it further comprises a third step of removing trifluoroacetic acid after producing benzenehexathiol.

[0041] [Note 7] A method for producing a nanosheet, comprising: a first step of preparing a raw material solution in which benzenehexathiol is dissolved in a water-soluble organic solvent; a second step of supplying the raw material solution to the surface of a substrate while a thin film of the aqueous solution is formed on the surface of the substrate, thereby forming a film of the raw material solution on the surface of the substrate; and a third step of removing the aqueous solution from the surface of the substrate to remove the organic solvent from the film of the raw material solution, thereby separating benzenehexathiol from the raw material solution and forming a sheet of benzenehexathiol on the surface of the substrate.

[0042] [Note 8] A method for producing a nanosheet as described in Appendix 7, characterized in that the second step involves floating the substrate in the aqueous solution contained in a container to form a thin film of the aqueous solution on the surface of the substrate, and the third step involves removing the aqueous solution by discharging it from the container.

[0043] It should be noted that the present invention is not limited to the embodiments described above, and it is clear that many modifications and combinations can be implemented within the technical concept of the present invention by those with ordinary skill in the art.

Claims

1. A first step involves reacting a toluenethiol having at least one methoxy group with one of hexafluorobenzene, hexachlorobenzene, or hexabromobenzene to produce a synthetic product. A second step involves dissolving the aforementioned compound in trifluoroacetic acid and heating it to remove the methoxybenzyl group from the aforementioned compound and produce benzenehexathiol. A method for producing benzenehexathiol, comprising [the specified characteristics].

2. In the method for producing benzenehexathiol according to claim 1, The first step involves reacting 4-methoxy-α-toluenethiol with hexafluorobenzene to synthesize hexakis(4-methoxybenzylthio)benzene as the compound. A method for producing benzenehexathiol, characterized by the above.

3. In the method for producing benzenehexathiol according to claim 1, The first step is characterized by being carried out in a solvent to which a base has been added, in a method for producing benzenehexathiol.

4. In the method for producing benzenehexathiol according to claim 1, The method for producing benzenehexathiol is characterized in that the second step is carried out by heating trifluoroacetic acid to 70°C.

5. In the method for producing benzenehexathiol according to claim 4, The second step is a method for producing benzenehexathiol, characterized by dissolving the compound in trifluoroacetic acid in which triethylsilane is dissolved.

6. In the method for producing benzenehexathiol according to any one of claims 1 to 5, A method for producing benzenehexathiol, further comprising a third step of removing trifluoroacetic acid after generating benzenehexathiol.

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