Novel eutectic solvent

Abstract

The present invention discloses novel eutectic solvents (NES) comprising one or more derivatives of methanesulfonic acid, one or more ammonium salts, and one or more hydrogen bond donors. The disclosed NES has characteristics such as low freezing and eutectic points, low viscosity, negligible vapor pressure, non-volatility, low water content, a wide potential window, high thermal stability, high solubility, long shelf life, high recyclability, high biodegradability, high ionic character, air and moisture stability, non-corrosiveness, non-mutagenicity, economical properties, and non-flammability, making it suitable for a wide range of applications.

Description

Technical Field

[0001] The present invention generally relates to chemical solvents, and more specifically to novel eutectic solvents containing derivatives of methanesulfonic acid. The novel eutectic solvents are expected to have a wide range of applications.

Background Art

[0002] A solvent is a chemical substance that dissolves a solute and has various applications in the chemical, pharmaceutical, petroleum and gas industries, etc., and is used in various processes and applications including electrochemical applications, chemical synthesis, electroplating, purification processes, etc., but is not limited thereto. The use of solvents generally involves the use of solvents in bulk amounts. Usually, solvents constitute about 80% of the total volume of chemical substances used in a specific application / process.

[0003] Conventional solvents including ethylene carbonate, dimethyl carbonate, propylene carbonate, etc. used in the industry are highly toxic, volatile, irritating, carcinogenic, mutagenic, costly, and difficult to apply to electrochemical applications, chemical synthesis, electroplating, purification processes for electrochemical applications, chemical synthesis, electroplating, and purification processes off, etc., and are not suitable for large-scale industrial applications. Therefore, the search, experiment, invention, development, and improvement of solvents that can be alternatives to conventional solvents have been continuously carried out for a long time.

[0004] Various alternatives have been proposed from time to time. Nevertheless, their uses have been limited due to slow kinetics (the reaction rate at which the reaction proceeds), low efficiency, and high capital costs.

[0005] The toxic solvents used in the chemical industry can simply be replaced with less harmful organic solvents such as ethyl alcohol. However, such replacement may not only be uneconomical but may also bring synthetic limitations.

[0006] In the search for green and sustainable alternative solvents to conventional solvents, ionic liquids have been studied and experimented with for decades. Several ionic liquids have been found as promising alternatives to conventional solvents due to their unique physical and chemical properties, such as a broad electrochemical potential window, high ionic conductivity, negligible vapor pressure, a wide temperature range over which the solvent remains liquid, excellent thermal stability, tunable solubility for both organic and inorganic molecules, and many synthetic flexibility. Furthermore, the discovery of room-temperature ionic liquids (RTILs) has increased the applications of ionic liquids as solvents. A review paper by Siddhartha Pandey titled "Analytical applications of room-temperature ionic liquids: A review of recent efforts," published in Analytica Chimica Acta 556(2006)38-45; doi:10.1016 / j.aca.2005.06.038, discusses the potential of RTILs in detail.

[0007] However, ionic liquids have their own limitations and drawbacks. Ionic liquids are mainly produced from petrochemical resources, and most production routes require the involvement of halogen atoms. Due to their low hydrolysis stability and high toxicity, the use of halogen components in ionic liquids is undesirable. The high production cost of RTILs compared to conventional solvents is a substantial limitation in expanding their industrial applications. In addition, several further drawbacks have been observed in common ionic liquids, including limited solute solubility, high viscosity, low biodegradability, and high disposal costs. A review paper titled "Toxicity of Ionic Liquids" by Dongbin Zhao et al., published in the clean journal; DOI: 10.1002 / clen.200600015, mentions the toxicity of ionic liquids.

[0008] In 2003, Abbott et al. proposed a new class of ionic liquids called eutectic solvents (ES), also known as deep eutectic solvents, which contain quaternary ammonium salts such as choline chloride and urea in a 1:2 molar ratio.

[0009] Eutectic solvents (ESs) are eutectic liquids that have a much lower melting point than the corresponding compound, forming complexes in the synthesis of the solvent. ESs are formed by mixing Lewis acids or Brønsted acids with bases, along with different cationic and anionic species. A review report by Emma L. Smith et al., titled "Deep Eutectic Solvents (DESs) and Their Applications," published in Chemical Reviews, dx.doi.org / 10.1021 / cr300162p | Chem. Rev. 2014, 114, 11060-11082 by the American Chemical Society, discusses various aspects of various existing ESs. Another review report titled "Deep eutectic solvents vs ionic liquids: Similarities and differences," published by Justyna Plotka-Wasylka et al. in the Microchemical Journal; https: / / doi.org / 10.1016 / j.microc.2020.105539, compares the properties of ionic liquids and eutectic solvents.

[0010] Generally available ES is a mixture of quaternary ammonium salts that have formed complexes with various hydrogen bond donor compounds in specific molar ratios. The purity of the resulting ES depends on the purity of the corresponding individual components. ES is considered to be easily manufactured in a cost-effective manner, has no problems after purification, and can be easily disposed of compared to conventional solvents and existing ionic solvents. ES is preferably liquid at ambient temperature. Due to its great potential as a solvent and industrial applications, ES is rapidly attracting interest as an alternative green solvent. Furthermore, ES is finding applications in CO2 absorption, although this is still in its early stages and there is considerable room for improvement.

[0011] However, like other solvents used in the chemical industry, existing ESs have limitations. The synthesis of existing ESs commonly involves the use of various types of quaternary ammonium salts, most of which are toxic. Generally, the components are stored in vacuum and must be dried before use in the preparation of ESs. Preparing common existing ESs requires mixing the components, slowly heating them at approximately 100°C for 8-10 hours, and then storing them in vacuum. Most ESs are inherently very viscous and difficult to handle. There is considerable room for improvement / modification in the ES manufacturing process and time. Furthermore, existing ESs require special preparation for storage to maintain their properties. Therefore, there is a need for novel ESs that address the limitations of existing ESs and improve upon desirable characteristics such as low freezing and eutectic points, low viscosity, negligible vapor pressure, non-volatility, lower water content, high potential window, high thermal stability, high solubility, long shelf life, high recyclability, high biodegradability, high ionic properties, air and moisture stability, non-corrosiveness, non-mutagenicity, economical properties, and non-flammability, resulting in a wider range of applications. [Overview of the Initiative]

[0012] The present invention discloses a novel ES (NES) that addresses the limitations of existing ESs, possesses the desired improved properties described above compared to existing ESs, and has a wider range of applications.

[0013] NES comprises one or more methanesulfonic acid derivatives selected from salts of methanesulfonic acid with various metal ions selected from the group consisting of manganese, zinc, cerium, nickel, titanium, copper, sodium, potassium, and calcium; one or more ammonium salts having the general formula NH4X (X can be selected from the group consisting of chloride, methanesulfonate, acetate, sulfate, triflate, and trimethanesulfonate); and one or more hydrogen bond donors selected from the group consisting of urea, thiourea, glycerol, oxalic acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, and citric acid, wherein the molar ratio of the methanesulfonic acid derivative, ammonium salt, and hydrogen bond donor(s) is in the range of 0.5 to 3:2 to 7:8 to 13. NES has a potential window ranging from 0.1V to 3.5V and a conductivity ranging from 10mS / cm to 90mS / cm. Furthermore, NES has a viscosity ranging from 1mPa·s to 60mPa·s. NES is in a liquid state at ambient pressure and temperatures down to 5°C. [Brief explanation of the drawing]

[0014] [Figure 1] Cyclic voltammetry curve of NES in Example 1 at a scan rate of 1 mV / s in a three-electrode system. [Figure 2] Voltage-time electrochemical stability and electroplating characteristics of NES in Example 1 at a current of 2.5 mA / cm² in an asymmetric carbon steel / Zn setup. [Figure 3] As the temperature increases, the energy obtained by the molecules in the NES in Example 1 increases along with the decrease in viscosity, thereby putting the ions in a higher energy state, which leads to an increase in mobility and an increase in the conductivity of the NES. [Modes for carrying out the invention]

[0015] I. Definition For the purpose of interpreting the specification and the attached claims, the following terms shall have the meanings set forth below. The term "solvent" refers to a liquid medium capable of dissolving other substances. The term "ambient temperature" refers to temperatures within the range of 25-30°C. The term "ambient pressure" shall mean atmospheric pressure at 1 bar.

[0016] II. Explanation Hereinafter, various embodiments of the present invention will be described in detail, with examples shown in the accompanying drawings. It will be understood that the invention described herein is not intended to be limited to these exemplary embodiments. The present invention is intended to encompass various substitutes, modifications, equivalents, and other embodiments that may fall within the spirit and scope of the invention as defined by the claims.

[0017] NES comprises one or more methanesulfonic acid derivatives selected from salts of methanesulfonic acid with various metal ions selected from the group consisting of manganese, zinc, cerium, nickel, titanium, copper, sodium, potassium, and calcium; one or more ammonium salts having the general formula NH4X (where X can be selected from the group consisting of chloride, methanesulfonate, acetate, sulfate, triflate, and trimethanesulfonate); and one or more hydrogen bond donors selected from the group consisting of urea, thiourea, glycerol, oxalic acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, and citric acid, wherein the molar ratio of the methanesulfonic acid derivative, ammonium salt, and hydrogen bond donor is in the range of 0.5 to 3:2 to 7:8 to 13. NES has a potential window in the range of 0.1 V to 3.5 V and a conductivity in the range of 10 mS / cm to 90 mS / cm. Furthermore, NES has viscosities ranging from 1 mPa·s to 60 mPa·s. NES is liquid at ambient pressures and temperatures down to 5°C.

[0018] NES is prepared by mixing one or more methanesulfonic acid derivatives selected from salts of methanesulfonic acid with various metal ions selected from the group consisting of manganese, zinc, cerium, nickel, titanium, copper, sodium, potassium, and calcium; one or more ammonium salts having the general formula NH4X (where X can be selected from the group consisting of chloride, methanesulfonate, acetate, sulfate, triflate, and trimethanesulfonate); and one or more hydrogen bond donors selected from the group consisting of urea, thiourea, glycerol, oxalic acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, and citric acid, wherein the molar ratio of the methanesulfonic acid derivatives, ammonium salts, and hydrogen bond donors is in the range of 0.5 to 3:2 to 7:8 to 13. When properly mixed, the mixture begins to change into a liquid at ambient temperature and pressure. To ensure proper mixing of the components and to speed up the process, the mixture may be uniformly heated to a temperature up to 60°C. After preparing the eutectic solvent, it can be stored in a container and can remain in a liquid state at low temperatures down to 5°C under ambient pressure.

[0019] The preparation of NES does not require special conditions such as heating / drying in a vacuum. Unlike many other eutectic solvents, the mixing of its components is an endothermic phenomenon, making the synthesis process safer and non-flammable than existing eutectic solvents. According to the present invention, the resulting transparent liquid NES can be stored in an airtight container at room temperature and is ready for use in a variety of applications.

[0020] NES is non-toxic and easily disposable due to the inherent properties of its constituent components, making it safer for the environment. Methanesulfonic acid is an organic acid that biodegrades to form sulfates with carbon dioxide. Furthermore, compared to other mineral acids, it is considered a green acid due to its lower toxicity and corrosiveness. The other components of the proposed NES are hydrogen bond donors and one or more ammonium salts, making NES biodegradable and eco-friendly.

[0021] Since all components of the NES are very economical and abundant in nature, the proposed NES is relatively economical compared to existing ESs and is a sustainable eutectic solvent. The proposed NES has low viscosity, high thermal and chemical stability, a wide potential window, low volatility, and is non-flammable. Due to the specific chemical properties and chemical bonds of the components, it is chemically and thermally stable with respect to existing solvents. Because of several advantages over existing ESs, ionic liquids, and organic solvents, the proposed NES has a wide range of applications including, but not limited to, electrochemical applications, energy storage devices, electroplating of metals, their composites and alloys, carbon dioxide capture, catalysis, organic synthesis, purification processes, biorefinery processes, pharmaceuticals, water treatment, metal processing, coating, electroless coating, synthesis of metal nanoparticles, electropolishing of metals, metal extraction, processing of metal oxides, gas adsorption, biotransformation, and electronics.

Examples

[0022] The following exemplary examples are provided to further illustrate the method of manufacturing and the method of using preferred NES compositions according to the present invention. These are not intended to limit the scope of the claimed invention.

[0023] Example 1 In the process of preparing the NES composition, 2 moles of zinc methanesulfonate, 10 moles of thiourea, and 5 moles of ammonium chloride are mixed in a rotary bottom flask. The flask is rotated at 50 rpm for proper mixing. After rotating for about 45 minutes, the solid mixture begins to change into the NES solvent. However, to accelerate the process towards rapid results, the components are mixed in an oil bath and rotated at 45 °C for 15 minutes to obtain a clear liquid NES solvent.

[0024] Example 2 In the process of preparing the NES composition, 1.7 moles of calcium methanesulfonate, 9 moles of thiourea, and 5 moles of ammonium chloride are mixed in a rotating-bottom flask. The flask is rotated at 50 rpm to ensure proper mixing. After rotating for approximately 45 minutes, the solid mixture begins to change into the NES solvent. However, for faster results, the components are mixed in an oil bath and rotated at 60°C for 15 minutes to obtain a clear liquid NES solvent.

[0025] Example 3 In the process of preparing the NES composition, 1.7 moles of calcium methanesulfonate, 10 moles of ethylene glycol, and 4 moles of ammonium acetate are mixed in a rotating-bottom flask. The flask is rotated at 50 rpm to ensure proper mixing. After rotating for approximately 45 minutes, the solid mixture begins to change into the NES solvent. However, for faster results, the components are mixed in an oil bath and rotated at 45°C for 15 minutes to obtain a clear liquid NES solvent.

[0026] IV. Experiment Experiment 1 Cyclic voltammetry is performed using a Biologic VPM3 electrochemical workstation, measuring 1 mVs within a voltage range of -1.5V to 2.5V (vs. Ag / AgCl). -1 The procedure is carried out using a three-electrode system comprising graphite as the working electrode, platinum mesh as the counter electrode, and Ag / AgCl as the reference electrode.

[0027] A cyclic voltammogram of a three-electrode system. To measure the potential window of NES number 1, the three-electrode system is used as shown above for a CV experiment, scanning from -1.5V to 2.5V at a scan rate of 1mV / s.

[0028] The cyclic voltammogram for NES in Example 1, shown in Figure 1, demonstrates the reversible electrochemical deposition / dissolution of zinc. The corresponding onset potentials for initial zinc plating / delamination are -0.31V and -0.01V. Compared with other existing solvents, NES shows a smaller potential separation between plating and delamination and a higher response current, suggesting better reversibility and faster kinetics of Zn deposition / dissolution. In particular, NES exhibits a broad and stable electrochemical window from -1.5V to 2V. The Coulomb efficiency (CE) gradually increases, reaching approximately 99.9% after 3 cycles.

[0029] Experiment 2 The electroplating and deplating capabilities of metals in NES solution are measured. A carbon steel working electrode (sheet: 10mm*0.2mm*50mm) and a zinc pair / reference electrode (diameter: 10mm*0.2mm*50mm) are suspended in a rectangular shape made up of carbon steel / / Zn asymmetric cells within the NES of Example 1. The results of the voltage-time electrochemical stability test of the Zn-carbon steel asymmetric cell are shown in Figure 2. The NES shows good electroplating capability. The NEC shows higher stability even with cycles.

[0030] Experiment 3 The effect of temperature changes on the ionic conductivity and viscosity of the NES in Example 1 will be measured. For measuring ionic conductivity, use the S230 Bench Conductivity Meter (Mettler-Toledo GmbH). Before each experiment, calibrate the instrument with a standard KCl solution.

[0031] A Dv2t Brookfield viscometer is used to evaluate the viscosity of NES.

[0032] [Table 1]

[0033] In both cases, a constant temperature water bath is used to control the temperature within ±0.5°C.

[0034] NES exhibited excellent ionic conductivity over the measurement temperature range of 10 to 60°C, increasing particularly at higher temperatures from 25.97 mS / cm to 81.42 mS / cm. This can be explained by the fact that as the temperature increases, the energy obtained by molecules in the NES medium increases along with the decrease in viscosity (from 50 mPa·s at 10°C to 5 mPa·s at 60°C), thus allowing ions to enter higher energy states, resulting in increased mobility and thus increased conductivity of NES. Since no decomposition products were observed, NES is thermally stable.

[0035] Referring to Figure 3, as the temperature increases, the energy obtained by the molecules in the NES increases along with the decrease in viscosity, causing the ions to enter a higher energy state. This leads to an increase in mobility, which in turn increases the conductivity of the NES.

[0036] Experiment 4 CO2 absorption is measured using the developed NES prepared in Examples 1, 2, and 3. CO2 gas is flowed at a rate of 10 ml / min into a 10 ml vial containing 5 ml of the prepared NES. The vial is weighed at regular intervals using a balance with an accuracy of 0.1 mg, and the weight percentage of absorbed CO2 is calculated. To reduce the effect of temperature, the vial is partially immersed in a water bath at a constant temperature during the experiment.

[0037] The test is prepared using the method described above and tested at a constant temperature of 27°C using a constant flow rate of CO2.

[0038] According to NES screening, calcium-containing NES showed high CO2 absorption capacity when measured against the fixed molar ratio of NES at atmospheric pressure.

[0039] Table 2 shows a comparison of CO2 uptake by each NES during a 2-hour experiment.

[0040] [Table 2]

Claims

1. One or more derivatives of methanesulfonic acid selected from salts of methanesulfonic acid with metal ions selected from the group consisting of manganese, zinc, cerium, nickel, titanium, copper, sodium, potassium, and calcium; General formula NH ４ One or more ammonium salts containing X (X can be selected from the group consisting of chlorides, methanesulfonates, acetates, sulfates, triflates, and trimethanesulfonates); One or more hydrogen bond donors selected from the group consisting of urea, thiourea, glycerol, oxalic acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, and citric acid. A novel eutectic solvent containing [the specified element].

2. The novel eutectic solvent according to claim 1, wherein the molar ratio of the methanesulfonic acid derivative, ammonium salt, and hydrogen bond donor is in the range of 0.5 to 3:2 to 7:8 to 13.

3. A novel eutectic solvent according to claim 1 or 2, having a potential window in the range of 0.1 V to 3.5 V.

4. A novel eutectic solvent according to any one of claims 1 to 3, having a conductivity in the range of 10 mS / cm to 90 mS / cm.

5. A novel eutectic solvent according to any one of claims 1 to 4, having a viscosity in the range of 1 mPa·s to 60 mPa·s.

6. A novel eutectic solvent according to any one of claims 1 to 5, which is in a liquid state at low temperatures of up to 5°C under ambient pressure.

Images