The present invention directs generally to chemical solvent and more particularly to a novel
5 eutectic solvent containing derivative(s) of the methanesulfonic acid. The novel eutectic
solvent has broad application prospects.
BACKGROUND OF THE INVENTION
Solvents are the chemical substances which dissolve a solute and have various applications
10 in chemical, pharmaceutical, oil & gas industries, etc. for multiple processes and
applications including but not limited to electrochemical application, chemical synthesis,
electroplating, purification processes, etc. The applications of solvents generally involve
their utilization in bulk quantities. Typically, solvents constitute around 80% of the total
volume of chemicals used in a specific application/ process.
15
The conventional solvents including ethylene carbonate, dimethyl carbonate, propylene
carbonate, etc., used in industries are highly toxic, volatile, irritant, carcinogenic,
mutagenic, costly, difficult to dispose to electrochemical application, chemical synthesis,
electroplating, purification processes to electrochemical application, chemical synthesis,
20 electroplating, purification processes off, etc. making them unsuitable for large scale
industrial application. Hence, possible alternatives to the conventional solvents are being
searched, experimented, invented, developed and improved for a long time.
Various alternatives were proposed from time to time. Still, they had limited application
25 due to slow kinetics (rate of the reactions at which reaction proceeds), low efficiencies and
high capital cost.
The toxic solvents utilized in the chemical industries can be simply replaced by the less
harmful organic solvents like ethyl alcohol; however, substitutions like these can result in
30 the synthetic restriction as well as can be non-economical.

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In search of green and sustainable alternative solvents as a replacement to the conventional
solvents, Ionic liquids have been studied and experimented upon since several decades.
Several ionic liquids have been found as prominent alternatives to the conventional
solvents due to their unusual physical and chemical properties, e.g. wide electrochemical
5 potential window, high ionic conductivity, negligible vapor pressures, wide temperature
range at which solvent remain at a liquid state, excellent thermal stability, adjustable
solubility for both organic and inorganic molecules, and much synthetic flexibility. Further,
the discovery of room temperature ionic liquids (RTIL) has increased application of ionic
liquids as solvents. A review article titled as “Analytical applications of room-temperature
10 ionic liquids: A review of recent efforts” by Siddhartha Pandey published at Analytica
Chimica Acta 556 (2006) 38–45; doi:10.1016/j.aca.2005.06.038, mentioned potential of
RTIL in detail.
However, ionic liquids can have their own limitations and shortcomings. Ionic liquids are
15 mostly manufactured from petrochemical resources, and most production routes require
the involvement of halogen atoms. Use of halogen components in ionic liquids is unwanted,
because of low hydrolysis stability, high toxicity. The further production cost of RTIL,
compared to conventional solvents, are real limitations in order to enlarge its applications
in the industry. Also, several additional disadvantages have been observed with common
20 ionic liquids, such as limited solute solubility, high viscosity, low biodegradability and
high disposal cost, etc. A review article titled as “Toxicity of Ionic Liquids” by Dongbin
Zhao et. al. published in clean journal; DOI: 10.1002/clen.200600015, mentions about
toxicity of Ionic liquids.
25 In the year 2003, a new class of ionic liquids called eutectic solvent (ES) also popularly
known as Deep Eutectic Solvent was proposed by Abbott et al. which contained quaternary
ammonium salt like choline chloride and urea in a molar ratio of 1:2.
ESs are eutectic liquids having melting points that are much lower than the melting point
30 of the corresponding compounds that are complexed in the synthesis of the solvent. ES is
formed by mixing Lewis or Bronsted acid and bases with different cationic and anionic
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species. A review report titled as “Deep Eutectic Solvents (DESs) and Their Applications”
by Emma L. Smith et. al. published in Chemical Reviews published by American Chemical
Society, dx.doi.org/10.1021/cr300162p | Chem. Rev. 2014, 114, 11060−11082 has
discussed various aspects of various existing ESs. Another review report titled as “ Deep
5 eutectic solvents vs ionic liquids: Similarities and differences” published in Microchemical
Journal by Justyna Płotka-Wasylka et.al.; https://doi.org/10.1016/j.microc.2020.105539,
has compared characteristics of Ionic Liquids against Eutectic solvents.

Commonly available ESs are mixtures of the quaternary ammonium salts complexed with
10 various hydrogen bond donor compounds in a particular molar ratio. The purity of the
resulting ESs depends on the purity of the corresponding individual components. ESs are
easy to manufacture in a cost-effective manner and does not involve any post purification
problem and considered to be easily disposable in comparison of the conventional solvents
and the existing Ionic solvents. ESs are preferably liquid at ambient temperatures. ESs are
15 rapidly gaining interest as alternative green solvents due to their enormous potential and
industrial applications as solvents. Further ESs have found their application in absorption
of CO2, however the same is still at nascent stage and there is a great scope of
improvement.
20 However, like other solvents used in the chemical industries, existing ESs have their
limitations. Usage of various kinds of quaternary ammonium salts is common in the
synthesis of existing ESs; however, the majority of the quaternary ammonium salts are
toxic. Generally, the components are stored in a vacuum and need drying before utilization
for preparation of the ES. While preparing commonly existing ESs, components are mixed
25 and slowly heated at around 100 degrees Celsius for 8-10 hours and are needed to store in
a vacuum. Most of the ESs are very viscous in nature and difficult to handle. There are lots
of scopes for improvement/amendment in the manufacturing process and time required for
manufacturing ESs. Further, existing ESs requires special arrangement for storage in order
to retain their property. Hence there is a requirement of a novel ES having answers to the
30 limitations present in the existing ESs and having improvements in desired features like
low freezing and eutectic points, low viscosity, negligible vapour pressure, non volatility,
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less water content, high potential window, high thermal stability, high solubility, long shelf
life, high recyclability, high biodegradability, high ionic character, air and moisture
stability, non-corrosive, non-mutagenic, economical, non-flammable etc., hence having
broader applications.
5
SUMMARY OF THE INVENTION
The present invention discloses a Novel ES (NES) which has answers to the limitations of
the existing ESs and has desired improved characteristics as mentioned above over the
existing ESs and has wider applications.
10
The NES is comprising one or more derivative(s) of methanesulfonic acid selected from
its salts with various metal ions selected from a group consisting of manganese, zinc,
cerium, nickel, titanium, copper, sodium, potassium and calcium; one or more ammonium
salt(s) having general formula NH4X, where X can be selected from a group consisting of
15 chloride, methanesulfonate, acetate, sulphate, triflate, trimethanesulfonate ; one or more
hydrogen bond donor(s) selected from a group consisting of urea, thiourea, glycerol, oxalic
acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, citric
acid ; wherein the molar ratio of derivative(s) of methanesulfonic acid, ammonium salt(s)
and hydrogen bond donor(s) is in the range 0.5-3: 2-7: 8-13. The NES having potential
20 window ranging from 0.1 to 3.5 V and conductivity ranging from 10 to 90 mS/cm. Further
the NES is having viscosity ranging from 1 to 60 mPa.s. NES remains liquid at a
temperature as low upto 5 °C at ambient pressure.
BRIEF DESCRIPTION OF DRAWINGS
25 Figure 1: Cyclic voltammetry curve of NES of Example 1 on a three-electrode system at
a scan rate of 1 mV/s.
Figure 2. Voltage-time electrochemical stability and electroplating characteristics of NES
of Example 1 in an asymmetrical Carbon Steel/Zn set-up at 2.5 mA/cm2
current.
30
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Figure 3. As temperature increases, the energy gained by the molecules in the NES of
Example 1 increases along with decrease in viscosity and hence the ions are in a higher
energy state which will lead to the mobility increases and hence the conductivity increases
in NES.
5
DETAILED DESCRIPTION OF INVENTION
I. DEFINITIONS
For purposes of interpreting the specification and appended claims, the following terms
10 shall be given the meaning set forth below:
The term “solvent” shall refer to a liquid medium capable of dissolving other substance(s).
The term “ambient temperature” shall mean temperature falling in the range of 25 to 30 °
15 C.
The term “ambient pressure” shall mean atmospheric pressure at 1 bar.
II. DESCRIPTION
20 Reference is hereby made in detail to various embodiments according to present invention,
examples of which are illustrated in the accompanying drawings and described below. It
will be understood that invention according to present description is not intended to be
limited to those exemplary embodiments. The present invention is intended to cover
various alternatives, modifications, equivalents and other embodiments, which may be
25 included within the spirit and scope of the invention as defined by the claims.
The NES is comprising one or more derivative(s) of methanesulfonic acid selected from
its salts with various metal ions selected from a group consisting of manganese, zinc,
cerium, nickel, titanium, copper, sodium, potassium and calcium; one or more ammonium
30 salt(s) having general formula NH4X, where X can be selected from a group consisting of
chloride, methanesulfonate, acetate, sulphate, triflate, trimethanesulfonate; one or more
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hydrogen bond donor(s) selected from a group consisting of urea, thiourea, glycerol, oxalic
acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, citric
acid; wherein the molar ratio of derivative(s) of methanesulfonic acid, ammonium salt(s)
and hydrogen bond donor(s) is in the range 0.5-3: 2-7: 8-13. The NES having potential
5 window ranging from 0.1 to 3.5 V and conductivity ranging from 10 to 90 mS/cm. Further
the NES is having viscosity ranging from 1 to 60 mPa.s. NES remains liquid at a
temperature as low up to 5°C at ambient pressure.
The NES is prepared by mixing one or more derivative(s) of methanesulfonic acid selected
10 from its salts with various metal ions selected from a group consisting of manganese, zinc,
cerium, nickel, titanium, copper, sodium, potassium and calcium; one or more ammonium
salt(s) having general formula NH4X, where X can be selected from a group consisting of
chloride, methanesulfonate, acetate, sulphate, triflate, trimethanesulfonate ; one or more
hydrogen bond donor(s) selected from a group consisting of urea, thiourea, glycerol, oxalic
15 acid, acetic acid, ethylene glycol, acetamide, benzamide, adipic acid, benzoic acid, citric
acid ; wherein the molar ratio of derivative(s) of methanesulfonic acid, ammonium salt(s)
and hydrogen bond donor(s) is in the range 0.5-3: 2-7: 8-13 are mixed. Upon proper mixing,
the mixture starts converting into a liquid at ambient temperature and pressure. To ensure
the proper mixing of the components and to speed up the process, this mixture may be
20 uniformly heated at a temperature up to 60°C. Once the eutectic solvent is prepared the
same can be stored in a container, which remains liquid at a low temperature up to 5°C at
ambient pressure.
No special condition of heating/drying in a vacuum is required in the preparation of NES.
25 Unlike many other eutectic solvents, the mixing of the constituting components is an
endothermic phenomenon, making synthesis process safer, non-flammable than existing
eutectic solvents. The resultant transparent liquid NES, according to the present invention,
is allowed to attain the room temperature and stored in an airtight container and ready to
be used for various applications.
30
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The NES is safer to environment being non toxicity and easily disposable due to inherent
nature of its constituents. Methanesulfonic acid is an organic acid which undergoes
biodegradation to form carbon dioxide and sulphate. It is also regarded as the green acid as
it is less toxic and corrosive in nature compared to the other mineral acids. The other
5 components of the proposed NES are hydrogen bond donor(s) and one or more kind of
ammonium salt making NES biodegradable and eco-friendly.
The NES is comparatively economical to the existing ESs as all the components are very
economic and abundant in nature, making the proposed NES a sustainable eutectic solvent.
10 The proposed NES has low viscosity, high thermal and chemical stability, wide potential
window, low volatility and non-flammability. The unique chemistry and chemical bonding
among the components make it chemically and thermally stable over the existing solvents.
Due to its several advantages on the existing ES, ionic liquids and organic solvents,
proposed NES has broad applications for including but not limited to the electrochemical
15 application, energy storage devices, electroplating of metals their composites and their
alloys, carbon dioxide capture, catalysis, organic synthesis, refinery process, biorefinery
process, pharmaceutical, water treatment, metal processing, coatings, electroless coatings,
metal nanoparticle synthesis, metal electropolishing, metal extraction, processing of the
metal oxides, gas adsorption, biotransformation and electronics.
20
EXAMPLES
The following illustrative examples are provided to further describe how to make and use
the preferred NES compositions according to present invention. The same are not intended
to limit the scope of the claimed invention.
25
EXAMPLE 1
In the process of preparing 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 @ 50 rpm for proper mixing. After rotating around 45 minutes the solid
30 mixture start converting into NES solvent. However, in order to expedite the process for
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speedy result, the components are mixed in oil bath and the rotation is done at 45°C for 15
minutes to obtain transparent liquid NES solvent.
EXAMPLE 2
5 In the process of preparing NES composition, 1.7 moles of calcium methanesulfonate 9
moles of thiourea and 5 moles of Ammonium Chloride are mixed in a rotary bottom flask.
The flask is rotated @ 50 rpm for proper mixing. After rotating around 45 minutes the solid
mixture start converting into NES solvent. However, for speedy result, the components are
mixed in oil bath and the rotation is done at 60°C for 15 minutes to obtain transparent liquid
10 NES solvent.
EXAMPLE 3
In the process of preparing NES composition, 1.7 moles of calcium methanesulfonate, 10
moles of Ethylene Glycol and 4 moles of Ammonium Acetate are mixed in a rotary bottom
15 flask. The flask is rotated @ 50 rpm for proper mixing. After rotating around 45 minutes
the solid mixture start converting into NES solvent. However, for speedy result, the
components are mixed in oil bath and the rotation is done at 45°C for 15 minutes to obtain
transparent liquid NES solvent.
20 IV. EXPERIMENTATION
EXPERIMENT 1
Cyclic voltammetry is done using Biologic VPM3 electrochemical workstation at 1 mV s1 within the voltage range from -1.5 V to 2.5 V (versus Ag/AgCl) using a three-electrode
system with graphite as the working electrode, Platinum Mesh as counter electrode, and
25 Ag/AgCl as reference electrode, respectively.
Cyclic voltammograms of a three-electrode system. To determine the potential window of
the NES number 1, three electrode system is used as mentioned above for CV experiment
at a scan rate of 1 mV/s from -1.5 V to 2.5.
30
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The cyclic voltammogram as shown in figure 1 for NES of example 1 indicates reversible
electrochemical deposition/dissolution of Zinc. The corresponding onset potentials of
initial Zinc plating/stripping are −0.31 V and −0.01 V. Compared to other existing solvents,
smaller potential separation between plating and stripping and higher response current can
5 be found for NES, suggesting better reversibility and faster kinetics of Zn deposition/
dissolution. Notably, NES exhibits a wide stable electrochemical window from -1.5V to
2V. The Coulombic efficiency (CE) gradually increased and reached around 99.9% after
the third cycle.
10 EXPERIMENT 2
To determine the metal electroplating and de-plating capacity in NES solution.
A Carbon Steel working electrode (Sheet: 10mm*0.2mm*50mm) and a Zinc
counter/reference electrode (diameter: 10mm*0.2mm*50mm) with a rectangle shaped
15 made up the Carbon steel//Zn asymmetric cells is suspended in NES of example 1.
The results of voltage-time electrochemical stability tests of the Zn-Carbon Steel
asymmetrical cell is shown in Figure 2. The NES shows good electroplating capabilities.
It displays greater stability even at cycling.
20 EXPERIMENT 3
To determine the effect of temperature variation on the ionic conductivity and viscosity of
NES of example 1.
A S230 Bench Conductivity Meter (Mettler-Toledo GmbH) is used to measure ionic
25 conductivity. Before each experiment, the equipment is calibrated against a standard KCl
solution.
An Dv2t Brookfield Viscometer is used to evaluate viscosities of NES
30 Table 1
Temp (°C) Conductivity (mS/cm) Viscosity (mPa.s)
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10 25.97 50
20 58.39 20
25 62.71 15
30 64.92 13
35 68.81 11
40 71.91 10
50 75.26 7
60 81.42 5
For both the cases temperature are controlled within ±0.5°C using a thermo-static, water
bath.
5 The NES gives better ionic conductivity over the measured temperature range of 10 to
60°C, especially at elevated temperatures that increased from 25.97 to 81.42 mS/cm. This
could be explained by the fact that as the temperature rises, the energy gained by the
molecules in the NES medium rises along with a decrease in viscosity (from 50mPa.s at
10 °C to 5mPa.s at 60 °C) and thus the ions are in a higher energy state, resulting in
10 increased mobility and thus increased conductivity in or NES. NES is thermally stable as
no breakdown products are observed.
Referring Figure 3, as temperature increases the energy gained by the molecules in the NES
increases along with decrease in viscosity and hence the ions are in a higher energy state
15 which will lead to the mobility increases and hence the conductivity increases in NES.
EXPERIMENT 4
CO2 absorption is measured using the developed NES of Examples 1, 2 and 3. CO2 gas is
flown into a vial (10 ml) holding 5 ml of developed NESs at a flow rate of 10 ml/min.
20 Weighing the vial at regular intervals with a weighing balance with an accuracy of 0.1 mg
is used to calculate the weight percent of CO2 absorbed. The vial is kept partially immersed
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in a water bath at constant temperatures during the experiment to reduce the effect of
temperature.
Test are prepared using the above method and tested using constant flow of CO2 and at
5 constant temperature of 27 °C.
According to the screening of NESs, NES containing Calcium showed high CO2 sorption
capacity, when measured at atmospheric pressure for the fixed molar ratio of NES.
10 Table 2 represents the comparative CO2 uptake of different NESs during 2h of experiment.
NES Temperature (⁰C) Pressure (Bar) CO2 uptake
(in mole)
NES of Example 1 27 ~1 0.283
NES of Example 2 27 ~1 0.461
NES of Example 3 27 ~1 0.398

We Claim:

1. A novel eutectic solvent comprising:
one or more derivative(s) of methanesulfonic acid selected from its salts with various
metal ions selected from a group consisting of manganese, zinc, cerium, nickel,
titanium, copper, sodium, potassium and calcium;
one or more ammonium salt(s) having general formula NH4X, where X can be
selected from a group consisting of chloride, methanesulfonate, acetate, sulphate,
triflate, trimethanesulfonate;
one or more hydrogen bond donor(s) selected from a group consisting of urea,
thiourea, glycerol, oxalic acid, acetic acid, ethylene glycol, acetamide, benzamide,
adipic acid, benzoic acid, citric acid.
2. The novel eutectic solvent as claimed in claim 1, wherein the molar ratio of
derivative(s) of methanesulfonic acid, ammonium salt(s) and hydrogen bond donor(s)
is in the range 0.5-3: 2-7: 8-13.
3. The novel eutectic solvent as claimed in any of the claims 1 or 2 has potential
windows ranging from 0.1 to 3.5 V.
4. The novel eutectic solvent as claimed in any of the claims 1 to 3 has conductivity
ranging from 10 to 90 mS/cm.
5. The novel eutectic solvent as claimed in any of the claims 1 to 4 has viscosity ranging
from 1 to 60 mPa.s.
6. The novel eutectic solvent as claimed in any of the claims 1 to 5 remains liquid at a
temperature as low up to 5°C at ambient pressure