FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE
SPECIFICATION
(See section 10; rule 13)
IONIC LIQUIDS
RELIANCE INDUSTRIES LIMITED
an Indian Company of,
3rd floor, maker chamber-IV
222, Nariman point, Mumbai-400021, Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED 2

FIELD
The present disclosure is related to ionic liquids.
BACKGROUND
Ionic liquids are composed of ionic species, cations and anions, which interact with each other and produce supra-molecular structural organization. Their interactions are weaker as compared to the common salts such as, sodium chloride comprising inorganic cations and inorganic anions. The ionic liquids have many useful properties, for e.g. they can be used as a polar solvent for chemical reactions. Since the ionic liquids produce negligible vapor pressure, they are less hazardous as compared to the conventional solvents.
However, ionic liquids are expensive as compared to the conventional solvents, since the preparation of ionic liquids involves the use of costly raw materials. Further, the conventional processes used for the preparation of the ionic liquids involve preparation of deep eutectic mixtures, often, at high temperature. The preparation of deep eutectic ionic liquids in larger quantities is tedious. Further, the resultant ionic liquid is viscous in nature and hence they are difficult to handle. 3

Thus, there is felt a need to provide an inexpensive ionic liquid and a simple, cost-effective, and energy efficient method for its preparation.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide an inexpensive ionic liquid.
Another object of the present disclosure is to provide a simple process for the preparation of the ionic liquid.
Still another object of the present disclosure is to provide a cost-effective and energy efficient process for the preparation of the ionic liquid.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure. 4

SUMMARY
In an aspect, the present disclosure provides an ionic liquid comprising at least one metal salt, at least one azole selected from the group consisting of imidazole, pyrazole, substituted imidazole, and substituted pyrazole, and a fluid medium. The metal salt is a salt of a metal selected from the group consisting of Al, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg. The salt is at least one selected from the group of salts consisting of chloride, bromide, iodide, sulfate, acetate, and chromate. The ratio of the amount of the metal salt to the amount of the azole ranges from 1:1 to 3:1. The fluid medium comprises at least one fluid selected from the group consisting of benzene, toluene, xylene, heptane, chlorobenzene, methoxybenzene, and substituted aromatic hydrocarbons. The ratio of the amount of the fluid medium to the amount of azole is in the range of 1:1 to 1:10. Due to the use of inexpensive raw materials, the ionic liquid of the present disclosure is inexpensive.
The ionic liquid is prepared by simply contacting in a fluid medium, at least one metal salt with at least one azole, and stirring at a 5

temperature is in the range of 10 C and 40 C for 30 minutes to 600 minutes.
The ionic liquid of the present disclosure can be used for various reactions such as alkylation, trans-alkylation, acylation, Diel-Alder reaction, Friedel-Craft reaction and oligomerization.
DETAILED DESCRIPTION
Ionic liquids are expensive, involve complex production process, and are difficult to handle. The present disclosure envisages an inexpensive ionic liquid that is easy to prepare and handle.
In one aspect, the present disclosure provides an ionic liquid comprising at least one metal salt, at least one azole selected from the group consisting of imidazole, pyrazole, substituted imidazole and substituted pyrazole, and a fluid medium.
In accordance with the embodiments of the present disclosure, the azole can be at least one selected from the group consisting of Imidazole, 1-methyl-imidazole, and 2-methyl-imidazole.
In accordance with one embodiment of the present disclosure, the azole is imidazole. 6

In accordance with another embodiment of the present disclosure, the azole is 1-methyl-imidazole.
In accordance with yet another embodiment of the present disclosure, the azole is 2-methyl-imidazole.In accordance with embodiments of the present disclosure, the metal salt is a salt of at least one metal selected from the group consisting of Al, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg.
In accordance with embodiments of the present disclosure, the salt is at least one selected from the group of salts consisting of chloride, bromide, iodide, sulfate, acetate, and chromate.
In accordance with embodiments of the present disclosure, the metal salt can be at least one selected from the group of salts consisting of aluminum trichloride, gallium trichloride, indium trichloride, ferric trichloride and chromium trichloride.
In accordance with one embodiment of the present disclosure, the metal salt is aluminum trichloride.
In accordance with another embodiment of the present disclosure, the metal salt is gallium trichloride. 7

In accordance with yet another embodiment of the present disclosure, the metal salt is indium trichloride.
In accordance with yet another embodiment of the present disclosure, the metal salt is ferric trichloride.
In accordance with yet another embodiment of the present disclosure, the metal salt is chromium trichloride.
In accordance with embodiments of the present disclosure, the ratio of the amount of the metal salt to the amount of the azole ranges from 1:1 to 3:1.
In accordance with one embodiment of the present disclosure, the ratio of the amount of the metal salt to the amount of azole is 3:2.
The azole has a lone pair of electrons that is available for coordination. The metal has empty orbitals that can accept the lone pair of electron. Thus, the azole acts as a Lewis base and the metal acts as a Lewis acid.
Combination of an azole and a metal salt result in the formation of a coordination complex containing an ion pair of a large cation and an anion. The diffuse charge of a large cation leads a weak electrostatic 8

interaction with the anion. A three-dimensional network of the weak electrostatic interactions among several ion pairs forms a continuous micro-domain structure of the ionic liquid.
The structure of the ionic liquid is further modified by the presence of the fluid medium resulting in the formation of the envisaged ionic liquid of the present disclosure.
In accordance with embodiments of the present disclosure, the fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, heptane, chlorobenzene, methoxybenzene, and substituted aromatic hydrocarbons.
In accordance with one embodiment of the present disclosure, the fluid medium is benzene.
In accordance with another embodiment of the present disclosure, the fluid medium is chlorobenzene.
In accordance with embodiments of the present disclosure, the ratio of the amount of the fluid medium to the amount of the azole is in the range of 1:1 to 10:1. 9

In accordance with one embodiment of the present disclosure, the ratio of the amount of the fluid medium to the amount of the azole is 2:1.
Characteristics of the ionic liquid of the present disclosure depend upon the nature of the metal salt, the azole, and the fluid medium. Requisite properties of ionic liquid can be obtained by choice of appropriate metal salt, azole, and fluid medium.
In another aspect, the present disclosure provides a process for the preparation of the ionic liquid of the present disclosure. The process comprises contacting in a fluid medium, at least one metal salt with at least one azole, followed by stirring the mixture at a predetermined temperature for a predetermined time to obtain the ionic liquid.
In accordance with embodiments of the present disclosure, the predetermined temperature is in the range of 10 C and 40 C.
In accordance with one embodiment of the present disclosure, the first predetermined temperature is room temperature i.e. 30 C.
In accordance with embodiments of the present disclosure, the predetermined time is in the range of 30 minutes and 600 minutes. 10

In accordance with one embodiment of the present disclosure, the first predetermined time is 180 minutes.
In conventional processes, ionic liquids are prepared as deep eutectic mixtures. The process of preparation of the ionic liquid often requires high temperature and it is time consuming. The preparation of deep eutectic ionic liquids in larger quantities is tedious. Further, the resultant ionic liquid is viscous in nature and hence they are difficult to handle.
However, it was found that, the process of the present disclosure involving contacting the azole with the metal salt in a fluid medium provides the ionic liquid at ambient temperature. Thus, the process for preparation of the ionic liquids of the present disclosure is simple, fast, cost-effective, and energy-efficient as compared to the conventional processes. Further, the ionic liquids of the present disclosure are non-viscous and easy to handle as compared to the deep eutectic mixtures.
The ionic liquids have supra-molecular structural organization of cations and anions bound by weak electrostatic interactions. Hence, 11

the ionic liquids can be used as polar liquid mediums for chemical reactions.
The ionic liquid of the present disclosure can be used for various reactions such as alkylation, trans-alkylation, acylation, Diel-Alder reaction, Friedel-Craft reaction and oligomerization.
It is observed that the ionic liquid of the present disclosure acts as a solvent as well as a catalyst for the alkylation of the aromatic compound. After completion of reaction, the ionic liquid of the present disclosure can be recycled.
In accordance with one exemplary embodiment of the present disclosure, the ionic liquid of the present disclosure has been used for alkylation of benzene using olefins present in a hydrocarbon stream to provide linear alkyl benzene (LAB). The LABs are commercially important compounds used for various applications such as the preparation of biodegradable detergents. The hydrocarbon stream containing olefins used for the alkylation can be a by-product of the petroleum and refinery industry. Thus, the LABs prepared by the process of the present disclosure are value added products. The process of LAB preparation is an environment-friendly process that 12

produces useful product by utilizing the by-product of petroleum and refinery industry. LABs are obtained in excellent yield by the alkylation of benzene with the hydrocarbon stream containing olefins in the presence of the ionic liquids of the present disclosure.
In accordance with another exemplary embodiment of the present disclosure, the ionic liquid of the present disclosure is used for oligomerization of olefins present in a hydrocarbon stream.
In accordance with yet another exemplary embodiment of the present disclosure, the ionic liquid of the present disclosure is used for Diel-Alder reaction.
In accordance with still another exemplary embodiment of the present disclosure, the ionic liquid of the present disclosure is used for acylation of benzene by acetyl chloride and benzoyl chloride.
The continuous micro domain structures of the ionic liquids formed due to the network of electrostatic interactions can be favorable for acid catalyzed reactions. Thus, the ionic liquids of the present disclosure can be used for catalyzing trans-alkylation, acylation, and Friedel-Crafts reactions. 13

The disclosure will now be described with reference to the following laboratory experiments, which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The laboratory scale experiments provided herein can be scaled up to industrial or commercial scale.
EXAMPLES
Example 1
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added Imidazole (10 g) followed by AlCl3 (29.41 g) and the resultant mixture was stirred for 180 minutes to obtain a homogenous ionic liquid (Imidazole-AlCl3) in benzene as a fluid medium.
Example 2
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added 1-methylimidazole (8.2 g) followed by AlCl3 (20.1 g) and stirred for 180 minutes to obtain a 14

homogenous ionic liquid (1-methylimidazole-AlCl3) in benzene as a fluid medium.
Example 3
In a reactor containing chlorobenzene (20 g) maintained under nitrogen atmosphere at room temperature, was added 1-methylimidazole (8.2 g) followed by GaCl3 (26.4 g) and stirred for 180 minutes to obtain a homogenous ionic liquid (1-methylimidazole-GaCl3) in chlorobenzene as a fluid medium.
Example 4
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added 2-methylimidazole (8.2 g) followed by GaCl3 (26.4 g) and stirred for 180 minutes to obtain a homogenous ionic liquid (2-methylimidazole-GaCl3) in benzene as a fluid medium.
Example 5
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added imidazole (6.8 g) followed by InCl3 (33.15 g) and stirred for 180 minutes to obtain a 15

homogenous ionic liquid (imidazole-InCl3) in benzene as a fluid medium.
Example 6
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added imidazole (6.8 g) followed by FeCl3 (24.3 g) and stirred for 180 minutes to obtain a homogenous ionic liquid (imidazole-FeCl3) in benzene as a fluid medium.
Example 7
In a reactor containing benzene (20 g) maintained under nitrogen atmosphere at room temperature, was added imidazole (6.8 g) followed by CrCl3 (23.7 g) and stirred for 180 minutes to obtain a homogenous ionic liquid (imidazole-CrCl3) in benzene as a fluid medium.
It was observed that the process for the preparation of ionic liquids of the present disclosure is simple and do not involve heating. The ionic liquid is non-viscous and easy to handle.
Example 8: Alkylation 16

To a reactor maintained under nitrogen atmosphere, was charged dry benzene (28 g) and a hydrocarbon stream containing 20% olefin (72 g) and the resultant mixture was heated to 45 C. Imidazole-AlCl3 ionic liquid (1 g) prepared in example 1 was added to the mixture, and the reaction mixture was stirred at 45 C for 10 minutes. Heating and stirring was stopped, and the layers were allowed to separate. The hydrocarbon layer was separated and analyzed using GC. Conversion of olefin to linear alkyl benzene was found to be 98.56 %. The ionic liquid layer was recycled.
Thus, the ionic liquid of the present disclosure acts as a solvent as well as a catalyst for the alkylation of benzene with a hydrocarbon stream and provides the alkylation product in an excellent yield.
EXAMPLE-9: Oligomerization
To a reactor maintained under nitrogen atmosphere, was charged a hydrocarbon stream (100 mL) containing 12 % C10-C14 olefins and 88% paraffins and heated to 45 oC. The ionic liquid catalyst (0.1 g) obtained in Example 1 was added to the reactor and the resultant mixture stirred for 10 minutes. The reaction mass was allowed to settle and the layers were separated. The upper hydrocarbon layer was 17

then analyzed. The conversion of olefins to oligomers was found to be 96%.
Thus, it was found that the ionic liquid of the present disclosure catalyzes the oligomerization of olefins with excellent conversion.
EXAMPLE-10: Diels Alder reaction
To a reactor maintained under nitrogen atmosphere, were charged Isoprene (2.76 g) and Vinyl Acetate (1.02 g) and the mixture was heated to 60oC. The ionic liquid catalyst (0.03 g) obtained in Example-1 was added to the reactor and resultant mixture was stirred for 4 hrs. Heating and stirring was stopped and the layers were allowed to separate. The conversion of reactants was found to be 95%.
Thus, it was found that the ionic liquid of the present disclosure catalyzes the Diel-Alder reaction with excellent conversion.
EXAMPLE-11: Acylation of Benzene by Acetyl Chloride
To a reactor maintained under nitrogen atmosphere, were charged Benzene (19.5 g) and Acetyl Chloride (3.5 g) and the mixture was 18

heated to 60oC. The ionic liquid catalyst (0.21 g) prepared as per Example-2 was added to the reactor and the reaction mixture was stirred for 2 hrs. The reaction workup was carried out with 25 mL distilled water. The conversion of Acetyl Chloride was found to be 95%.
EXAMPLE-12: Acylation of Benzene by Benzoyl Chloride
To a reactor maintained under nitrogen atmosphere, were charged Benzene (19.5 g) and Benzoyl Chloride (1.95 g) and the mixture was heated to 60oC. The ionic liquid catalyst (0.21 g) prepared as per Example-4 was added to the reactor and the reaction mixture was stirred for 3 hrs. The reaction workup was carried out with 15 mL distilled water & 15 mL ethyl acetate. The conversion of Benzoyl Chloride was found to be 94%.
Thus, it was found that the ionic liquid of the present disclosure catalyzes the acylation with excellent conversion. 19

TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
 inexpensive ionic liquids;
 a simple, cost-effective, and energy efficient process for the preparation of the ionic liquid; and
 an alkylation process for the preparation of LABs in high yield using a hydrocarbon stream comprising olefins in the presence of the ionic liquids.

Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results. 20

Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of 21

the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation. 22

WE CLAIM:
1. An ionic liquid comprising at least one metal salt, at least one azole selected from the group consisting of imidazole, pyrazole, substituted imidazole, and substituted pyrazole; and a fluid medium; wherein the molar ratio of the amount of the metal salt to the amount of the azole ranges from 1:1 to 3:1.

2. The ionic liquid as claimed in claim 1, wherein the azole is at least one selected from the group consisting of imidazole, 1-methyl-imidazole, and 2-methyl-imidazole.

3. The ionic liquid as claimed in claim 1, wherein the metal salt is a salt of a metal selected from the group consisting of Al, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg.

4. The ionic liquid as claimed in claim 1, wherein the salt is at least one selected from the group of salts consisting of chloride, bromide, iodide, sulfate, acetate, and chromate.
23

5. The ionic liquid as claimed in claim 1, wherein the metal salt is at least one selected from the group of salts consisting of aluminum trichloride, gallium trichloride, indium trichloride, ferric trichloride and chromium trichloride.

6. The ionic liquid as claimed in claim 1, wherein the fluid medium is at least one selected from the group consisting of benzene, toluene, xylene, heptane, chlorobenzene, methoxybenzene, and substituted aromatic hydrocarbons.

7. The ionic liquid as claimed in claim 1, wherein the ratio of the amount of the fluid medium to the amount of the azole is in the range of 1:1 to 10:1.

8. A process for the preparation of the ionic liquid as claimed in claim 1; said process comprising contacting in a fluid medium, at least one metal salt with at least one azole selected from the group consisting of imidazole, pyrazole, substituted imidazole and substituted pyrazole, followed by stirring at a
24

predetermined temperature for a predetermined time to obtain the ionic liquid.

9. The process as claimed in claim 8, wherein the predetermined temperature is in the range of 10 C and 40 C; and the predetermined time is in the range of 30 minutes and 600 minutes.