FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
AND
THE PATENTS RULES, 2003
COMPLETE
SPECIFICATION
(See section 10; rule 13)
2-PYRROLIDONE BASED IONIC LIQUIDS
RELIANCE INDUSTRIES LIMITED
an Indian company of,
3rd Floor, Maker Chamber-IV,
222, Nariman Point, Mumbai 400 021, Maharashtra, India
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED 2

FIELD
The present disclosure relates to ionic liquids.
BACKGROUND
Ionic liquids can be used as fluid media and catalysts for many industrial processes because of useful properties associated with them.
Diverse areas such as electrochemistry, synthesis of chemical compounds, batteries, photovoltaic devices, electro-deposition processes, and semi-conductor cleaning sometimes use ionic fluids in place of conventional molecular fluid media.
The use of ionic liquids is advantageous over conventional organic fluid media because they do not produce harmful vapor, have high ionic conductivity and are non-flammable. The ionic liquids are also used as a green fluid media and catalysts in organic synthesis.
An ionic liquid is composed of at least two components, an anionic component and a cationic component, which form a complex. Typically, a Lewis acid is one of the components of an ionic liquid. When the amount of the Lewis acid is higher than the amount of the 3

second component, the resultant ionic liquid is acidic in nature. However, the ionic liquids derived from Lewis acid are associated with drawbacks such as high cost and decomposition at high temperature. Further, in certain cases, component/s of the ionic liquid can be an environmental burden.
Thus, there is felt a need to provide an ionic liquid derived from Lewis acid that is cost-effective, stable at high temperature and environment friendly.
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 ionic liquid derived from Lewis acid that is stable at high temperature. 4

Another object of the present disclosure is to provide an environment friendly ionic liquid derived from Lewis acid.
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.
SUMMARY
One aspect of the present disclosure provides an ionic liquid comprising at least one 2-pyrrolidone compound and at least one Lewis acid.
2-Pyrrolidone compounds have a relatively high boiling point which ensures stability of the ionic liquid even at a high temperature. 2-Pyrrolidone compounds are biodegradable and therefore, the ionic liquids of the present disclosure are environment friendly. The ionic liquid of the present disclosure is cost effective because of the use of 2-pyrrolidone compounds, which are relatively inexpensive. 5

In accordance with the embodiments of the present disclosure, the molar ratio of the 2-pyrrolidone compound to the Lewis acid in the ionic liquid is in the range from 1:1 to 1:6.
The ionic liquid of the present disclosure can be used for various reactions such as alkylation, trans-alkylation, acylation, oligomerization, Diel-Alder reaction, and Friedel-Craft reaction.
DETAILED DESCRIPTION
Ionic liquids comprise a cationic component and an anionic component that interact with each other and form a complex. Ionic liquids derived from Lewis acid are associated with certain drawbacks as described hereinabove. The present disclosure envisages an ionic liquid derived from a Lewis acid that is stable at high temperature and environment friendly.
In accordance with an aspect of the present disclosure, there is provided an ionic liquid comprising at least one 2-pyrrolidone compound and at least one Lewis acid. The 2-pyrrolidone compound is an electron rich molecule, which shares a lone pair of electrons 6

with the electron deficient metal center of a metal salt and thereby forms an ionic liquid.
The 2-pyrrolidone compound is at least one selected from the group consisting of 1H-2-pyrrolidone, n-methyl-2-pyrrolidone and n-ethyl-2-pyrrolidone.
2-Pyrrolidine compounds have boiling points above 200 C. The high boiling point provides stability to the ionic liquid at high temperatures. Ionic liquids of the present disclosure show good thermal conductivity and stability. 2-pyrrolidone compounds are inexpensive fluid media and are biodegradable and hence the ionic liquids of the present disclosure are cost-effective and environment friendly.
In accordance with one embodiment of the present disclosure, the 2-pyrrolidone compound is 1H-2-pyrrolidone.
In accordance with another embodiment of the present disclosure, the 2-pyrrolidone compound is 1-methyl-2-pyrrolidone (NMP). 7

The Lewis acid can be a metal salt of a metal selected from the group consisting of Al, Mg, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, In, Sn, Ti, Pb, Cd, and Hg.
In accordance with the embodiments of the present disclosure, the metal salt is selected from the group of salts consisting of chloride, bromide, iodide, sulfate, acetate, and chromate, typically a chloride salt.
In accordance with one embodiment of the present disclosure, the Lewis acid is aluminum trichloride (AlCl3).
In accordance with another embodiment of the present disclosure, the Lewis acid is gallium trichloride (GaCl3).
In accordance with yet another embodiment of the present disclosure, the Lewis acid is ferric trichloride (FeCl3).
Other Lewis acids such as CrCl3, MnCl2, FeBr2, CoCl2, NiI2, CuCl2, ZnCl2, GaCl3, GeBr2, InCl3, SnCl2, TiCl3, and CdCl2, will interact with 2-pyrrolidone compounds in the similar way as AlCl3, and form ionic liquids as envisaged in accordance with this disclosure. 8

In accordance with the embodiments of the present disclosure, the molar ratio of the 2-pyrrolidone compound to the Lewis acid is in the range from 1:1 to 1:6.
In accordance with the preferred embodiments of the present disclosure, the molar ratio of the 2-pyrrolidone compound to the Lewis acid is in the range from 1:1 to 1:3.
In accordance with one embodiment of the present disclosure, the molar ratio of the 2-pyrrolidone compound to the Lewis acid is 1:1.5.
In accordance with the embodiments of the present disclosure, the ionic liquid optionally comprises at least one fluid medium selected from the group consisting of benzene, toluene, xylene, chlorobenzene, methoxybenzene, and substituted aromatic compounds.
The ratio of the amount of the ionic liquid to the amount of the fluid medium ranges from 10:1 to 1:10.
The ionic liquids of the present disclosure can be used as a catalyst and as a solvent for various reactions such as alkylation, trans-alkylation, acylation, Diel-Alder reaction, Friedel-Craft reaction, and 9

oligomerization. These reactions can be carried out using 0.1% to 10% w/w of the ionic liquids of the present disclosure, as a catalyst.
The ionic liquids of the present disclosure are found to be stable at a temperature up to 250 C.
The alkylation of benzene with olefins in the presence of the ionic liquid of the present disclosure provides an excellent yield of linear alkyl benzenes (LABs).
Oligomerization of olefins is catalyzed at high conversion rate by the ionic liquids of the present disclosure.
Further, the trans-alkylation of heavier alkyl benzene (HAB) with benzene in the presence of the ionic liquid of the present disclosure provides good yield of linear alkyl benzenes (LABs).
Furthermore, ionic liquid of the present disclosure can efficiently catalyze the Diel-Alder reaction.
The ionic liquid of the present disclosure can be used in place of the conventional catalyst used for other reactions such as acylation, and Friedel-Craft reactions. 10

In accordance with the exemplary embodiments of the present disclosure, the reactions catalyzed by the ionic liquids of the present disclosure are demonstrated with NMP-based ionic liquid comprising AlCl3. However, the 2-pyrrolidone-based ionic liquids comprising other metal salts catalyze these reactions in a similar fashion.
After the reaction the ionic liquid can be separated and the separated ionic liquid can be reused as a catalyst.
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.
Experiments
The ionic liquid of the present disclosure can be prepared in the form of a eutectic mixture or a solution in a fluid medium.
Experiment 1: 11

1-Methyl-2-pyrrolidone (NMP) (10 g, 0.1 mol) was mixed with AlCl3 (20.2 g, 0.15 mol) under nitrogen atmosphere at room temperature. The resultant mixture was stirred for 3.5 hours to obtain NMP-AlCl3 ionic liquid in the form of a eutectic mixture.
Experiment 2:
1-Methyl-2-pyrrolidone (NMP) (10 g, 0.1 mol) was mixed with AlCl3 (20.2 g. 0.15 mol) in benzene as a fluid medium (30 g) under nitrogen atmosphere at room temperature. The resultant mixture was stirred for 3 hours to obtain NMP-AlCl3 ionic liquid in benzene.
Experiment 3:
1-H-2-pyrrolidone (8.5 g, 0.1 mol) was mixed with AlCl3 (20.2 g. 0.15 mol) in benzene as a fluid medium (30 g) under a nitrogen atmosphere at room temperature. The resultant mixture was stirred for 3 hours to obtain an ionic liquid in benzene.
Experiment 4:
1-Methyl-2-pyrrolidone (NMP) (10 g, 0.1 mol) was mixed with GaCl3 (26.5 g. 0.15 mol) in benzene as a fluid medium (30 g) under a 12

nitrogen atmosphere at room temperature. The resultant mixture was stirred for 3 hours to obtain NMP-GaCl3 ionic liquid in benzene.
Experiment 5:
1-Methyl-2-pyrrolidone (NMP) (10 g, 0.1 mol) was mixed with FeCl3 (24.5 g. 0.15 mol) in benzene as a fluid medium (30 g) under a nitrogen atmosphere at room temperature. The resultant mixture was stirred for 3 hours to obtain NMP-FeCl3 ionic liquid in benzene.
Experiment 6: Alkylation of benzene with a hydrocarbon feed
A hydrocarbon feed containing paraffins and olefins was used as an alkylating agent for the alkylation of benzene. The product of the alkyaltion of benzene was linear alkyl benzene (LAB).
Hydrocarbon feed containing 20% olefin (72.0g) was mixed with benzene (28.0 g) and the flask was heated at 45 C under nitrogen atmosphere. NMP-AlCl3 ionic liquid (1.0 g, 1% w/w) obtained in Experiment-2 was added to the reaction mixture and the reaction mixture was heated at 45 C for 10 minutes. 13

The reaction mixture was cooled to room temperature. The hydrocarbon layer was separated and analyzed by GC. The conversion of olefins to LAB was found to be 98%.
Thus, the NMP-based ionic liquids provides high yield of LAB.
Experiment-7: Oligomerization
A hydrocarbon stream (100 mL) containing 12% C10-C14 olefins and 88% paraffins were charged into a reactor maintained under nitrogen atmosphere. The content of the reactor was heated to 45 C, and the ionic liquid (0.1 g) obtained in Experiment-1 was added to the reactor. The resultant mixture was stirred at 45 C for 10 minutes, followed by cooling the reaction mass and allowing it to settle. Analysis of the upper hydrocarbon layer showed 97% conversion of the olefins to oligomers.
Experiment-8: Trans-alkylation reaction of higher alkyl benzenes
11.7 ml (10.0 gm) of heavier alkyl benzene stream, containing 7% linear alkyl benzene and 93% heaviers such as dilakylbenzenes and oligomers, was added to a reactor maintained under nitrogen atmosphere. The content was heated to 85 oC and 6.9 ml (6.0 gm) of 14

benzene was added to the reactor. The resultant mixture was heated to 85 oC under stirring for 15 mins, followed by addition of 1.1 gm (1% w/w) of NMP-AlCl3 ionic liquid obtained in Experiment-2. The reaction mixture was stirred for 2 hours at 85 oC. The reaction mixture was cooled, allowed to settle and layers were separated. The upper layer was the hydrocarbon layer and the lower layer was catalyst layer. The upper layer was analyzed by gas chromatography. The conversion of heaviers was 75% with 75% selectivity towards the formation of LAB.
The lower layer containing ionic liquid was recycled. Further, the ionic liquid was stable at high temperature.
Experiment-9: Diels Alder reaction
Isoprene (2.76 g) and vinyl acetate (1.02 g) were charged to a reactor maintained under nitrogen atmosphere. The content of the reactor was heated to 60 C followed by addition of NMP-AlCl3 ionic liquid (0.03 g) obtained in Experiment-1. The reaction mixture was stirred at 60 C for 4 hours. The reaction mixture was cooled, and layers were allowed to separate. Analysis of the hydrocarbon layer showed 95% of the desired product. The catalyst layer was separated and recycled. 15

TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of ionic liquids derived from Lewis acids that:
 are stable at high temperature;
 are environment-friendly catalysts and fluid media; and
 are cost-effective catalysts and fluid media.

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 16

be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
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 17

departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of 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. 18

We Claim:
1. An ionic liquid comprising at least one 2-pyrrolidone compound and at least one Lewis acid; wherein the molar ratio of the 2-pyrrolidone compound to the Lewis acid is in the range from 1:1 to 1:6.
2. The ionic liquid as claimed in claim 1, wherein the 2-pyrrolidone compound is at least one selected from the group consisting of 1H-2-pyrrolidone, n-methyl-2-pyrrolidone, and n-ethyl-2-pyrrolidone.
3. The ionic liquid as claimed in claim 1, wherein the Lewis acid 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 selected from the group consisting of chloride, bromide, iodide, sulfate, acetate, and chromate.
5. The ionic liquid as claimed in claim 1, wherein the Lewis acid is selected from a group consisting of aluminum trichloride (AlCl3), gallium chloride (GaCl3), and ferric chloride (FeCl3).
19

6. The ionic liquid as claimed in claim 1, wherein the ionic liquid optionally comprises at least one fluid medium selected from the group consisting of toluene, benzene, xylene, chlorobenzene, methoxybenzene, and substituted aromatic compounds.
7. The ionic liquid as claimed in claim 1, wherein the ratio of the amount of the ionic liquid to the amount of the fluid medium ranges from 10:1 to 1:10.