DESC:FIELD
The present disclosure relates to a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
BACKGROUND
The background information hereinbelow relates to the present disclosure but is not necessarily prior art.
2-(2,6-diethyl-4-methyl-phenyl)–malononitrile, is an intermediate for the synthesis of a phenylpyrazoline based herbicide i.e. Pinoxaden. Pinoxaden is known to inhibit Acetyl-CoA carboxylase (ACC) in the weeds and unwanted plants, thereby blocking fatty acid synthesis, hindering cell division, and resulting in the destruction of the cell membrane lipid structure that leads to weed death.
Conventional processes for the synthesis of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile provide low purity products. Further, most of the purification process is cumbersome, time-consuming, and not environment friendly.
The conventional route for preparing 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile involves the use of a homogeneous palladium catalyst in its synthesis. The source of palladium catalyst used in the process are PdCl2 in HCl, PDCl2 (TPP)2, tetrakis(triphenylphosphine) palladium, and the like for catalyzing the C-C coupling reaction. However, palladium is found in many streams of the reaction product and intermediates having lower purity and comparatively lesser yields. Moreover, the cost of palladium is very high leading to a non-economical process for the commercial application.
There is, therefore, felt a need for a process for preparing 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile that mitigates the drawbacks mentioned hereinabove.
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.
Another object of the present disclosure is to provide a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
Still another object of the present disclosure is to provide a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile that results in relatively high purity and high yield of the product.
Yet another object of the present disclosure is to provide a simple and efficient process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
Another object of the present disclosure is to provide a process for the preparation
of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile avoiding the use of noble metal catalyst like palladium.
Another object of the present disclosure is to provide a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile, wherein the halide used during the process is recovered and reused.
Still another object of the present disclosure is to provide a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile that uses cheaper and easily available raw materials.
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
The present disclosure relates to a process for the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The process comprises reacting paraformaldehyde with propanaldehyde by using a first base at a temperature in the range of 70 °C to 100 °C for a time period in the range of 2 hours to 5 hours to obtain methacrolein. Separately, 4-heptanone is reacted with malononitrile in a first fluid medium by using a second base at a temperature in the range of 100 °C to 140 °C for a time period in the range of 2 hours to 6 hours to obtain 2-(heptan-4-ylidene)malononitrile. Further, methacrolein is reacted with 2-(heptan-4-ylidene)malononitrile by using a third base in a second fluid medium at a temperature in the range of 100 °C to 140 °C for a time period in the range of 8 hours to 20 hours to obtain 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile. The so obtained 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile is reacted with a halide in a third fluid medium optionally by using a fourth base in an inert atmosphere at a temperature in the range of 120 oC to 140 oC to obtain 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, known processes or well-known apparatus or structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure are not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
2-(2,6-diethyl-4-methyl-phenyl)–malononitrile, is an intermediate for the synthesis of a phenylpyrazoline based herbicide i.e. Pinoxaden. Pinoxaden is known to inhibit Acetyl-CoA carboxylase (ACC) in the weeds and unwanted plants, thereby blocking fatty acid synthesis, hindering cell division, and resulting in the destruction of the cell membrane lipid structure that leads to weed death. Conventional processes for the synthesis of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile provide low purity products. Further, most of the purification process is cumbersome, time-consuming, and not environment friendly. The conventional route for preparing 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile involves the use of a homogeneous palladium catalyst in its synthesis. The source of palladium catalyst used in the process are PdCl2 in HCl, PDCl2 (TPP)2, tetrakis(triphenylphosphine) palladium, and the like for catalyzing the C-C coupling reaction. However, palladium is found in many streams of the reaction product and intermediates having lower purity and comparatively lesser yields. Moreover, the cost of palladium is very high leading to a non-economical process for the commercial application.
The process of the present disclosure provides a simple, environment-friendly, and economical process that, results in improved yield and higher purity of 2-(2, 6-Diethyl-4-methyl-phenyl)-malononitrile.
The present disclosure relates to the process for preparing 2-(2, 6-Diethyl-4-methyl-phenyl)-malononitrile of formula (I),

(I)
The process is described in detail.
In a first step, paraformaldehyde is reacted with propanaldehyde by using a first base at a temperature in the range of 70 oC to 100 oC for a time in the range of 2 hours to 5 hours to obtain methacrolein. In an embodiment, the reaction is carried out at 80 oC for 3 hours.
In accordance with one embodiment, the first base is at least one selected from morpholine and diethanolamine. In an exemplary embodiment of the present disclosure, the first base is morpholine.
In accordance with the present disclosure, the molar ratio of the propanaldehyde to the paraformaldehyde is in the range of 1:0.9 to 1:1.2. In an exemplary embodiment, the molar ratio of propanaldehyde to paraformaldehyde is 1:0.98.
In an embodiment, the predetermined condition is acidic. The acid used to obtain the acidic condition is selected from H2SO4 and HCl. In an exemplary embodiment, the acid is sulphuric acid (H2SO4).
The schematic representation of the preparation of methacrolein in accordance with the present disclosure is illustrated in Scheme 1.

Scheme 1
In a second step, separately 4-heptanone is reacted with malononitrile in a first fluid medium by using a second base at a temperature in the range of 100 oC to 140 oC (azeoptropically) for a time period in the range of 2 hours to 6 hours to obtain 2-(heptan-4-ylidene)malononitrile. In an embodiment, the reaction is carried out at 110 oC for 4 hours. In another embodiment, the reaction is carried out at 130 °C to 135 °C for 4 hours.
In accordance with one embodiment, the second base is a weak base. In an embodiment, the weak base is ammonium acetate. In an exemplary embodiment of the present disclosure, the second base is ammonium acetate.
In an embodiment, the first fluid medium is selected from toluene, monochlorobenzene (MCB), and dichlorobenzene. In an exemplary embodiment of the present disclosure, the first fluid medium is toluene. In another exemplary embodiment of the present disclosure, the first fluid medium is monochlorobenzene (MCB).
The schematic representation of the preparation of 2-(heptan-4-ylidene)malononitrile in accordance with the present disclosure is given below as Scheme 2.

Scheme 2
In a third step, methacrolein obtained in the first step is reacted with the 2-(heptan-4-ylidene)malononitrile obtained in the second step by using a third base in a second fluid medium to obtain 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile.
In accordance with an embodiment, the third base is selected from trimethylamine, triethylamine, and tributylamine. In an exemplary embodiment of the present disclosure, the third base is triethylamine.
In an embodiment, the second fluid medium is at least one selected from the group consisting of toluene and monochlorobenzene (MCB). In an exemplary embodiment of the present disclosure, the second fluid medium is monochlorobenzene.
The reaction of methacrolein and 2-(heptan-4-ylidene)malononitrile is carried out at a temperature in the range of 100 oC to 140 oC for a time in the range of 8 hours to 20 hours. In an embodiment, the reaction is carried out at 112 oC for 10 hours.
The schematic representation of the preparation of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile in accordance with the present disclosure is given below as Scheme 3.


Scheme 3
In a fourth step, 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile is reacted with a halide in a third fluid medium optionally by using a fourth base in an inert atmosphere at a temperature in the range of 120 oC to 140 oC to obtain 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
In an embodiment, the halide is at least one selected from bromine solution, iodine solution, and solid iodine. In an exemplary embodiment of the present disclosure, the halide is a bromine solution. In another exemplary embodiment of the present disclosure, the halide is an iodine solution. In yet another exemplary embodiment of the present disclosure, the halide is a bromine-iodine solution.
In accordance with the process of the present disclosure, the halide used during the process is recovered and reused and hence the process is economical and environment friendly.
In an embodiment, the third fluid medium is selected from monochlorobenzene (MCB), bromobenzene, nitrobenzene, and orthodichlorobenzene. In an exemplary embodiment of the present disclosure, the third fluid medium is monochlorobenzene (MCB).
In accordance with an embodiment, the fourth base is selected from the group consisting of calcium carbonate and sodium carbonate. In an exemplary embodiment of the present disclosure, the fourth base is calcium carbonate. In another exemplary embodiment of the present disclosure, the fourth base is sodium carbonate.
In an embodiment, the inert atmosphere is selected from nitrogen and argon. In an exemplary embodiment of the present disclosure, the inert atmosphere
In an embodiment, a mole ratio of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile to the fourth base is in the range of 1:1 to 1:2. In an exemplary embodiment, the mole ratio of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile to the fourth base is 1: 1.5.
The schematic representation of the preparation of 2-(2, 6-diethyl-4-methyl-phenyl)-malononitrile in accordance with the present disclosure is given below as Scheme 4.

Scheme 4
The process of the present disclosure employs inexpensive and easily available reagents. Thus, the process of the present disclosure is economical.
The process of the present disclosure is simple, reduces solvent use, and hence economical.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further illustrated hereinbelow with the help of the following experiments. The experiments used herein are intended merely to facilitate an understanding of the ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the experiments should not be construed as limiting the scope of embodiments herein. These laboratory scale experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial/commercial scale.
EXPERIMENTAL DETAILS:
EXPERIMENT 1:
Step I- Preparation of methacrolein in accordance with the present disclosure
Example – 1a:
50 gm of water and 0.3 mole morpholine were mixed at 30°C to obtain a mixture. 0.16 moles conc. H2SO4 (98 %) was added to the mixture in a dropwise manner to obtain an acidic mixture having a pH of up to 2 (acidic). The acidic mixture was stirred at 30oC followed by adding 0.98 mole paraformaldehyde under stirring at 80 °C for 3 hours to obtain a clear solution. The solution was cooled to 40 °C and subsequently, 1 mole of propanaldehyde was added under stirring to obtain a reaction mixture. The reaction mixture was refluxed for 3 hours to obtain a product. The product was distilled over a short column (by using 1- 2 feet packed column and cleisen head) to obtain a distillate and a residual mass. The so obtained distillate was cooled to 30oC. The distillate thus obtained contains two layers and both the layers were analysed for purity. The top layer containing methacrolein was separated from the distillate. The distilled yield was 85 %, purity 98% and the yield on purity was 83%.

Example – 1b: Recycle of residual mass
The residual mass obtained in example 1a) was recycled by adjusting the pH to 2.0 by using either morpholine or H2SO4. The recycled mass was used for the next batch, which can provide a yield similar to 1a.
EXPERIMENT 2:
Step II- Preparation of 2-(heptan-4-ylidene)malononitrile in accordance with the present disclosure
Example - 2: Preparation of 2-(heptan-4-ylidene)malononitrile using toluene
4-hepatanone (1.0 mol) and malononitrile (1.05 moles) were mixed in toluene (1000 ml) followed by adding ammonium acetate (0.15 mole) and acetic acid (0.3 moles) at 30oC to obtain a mixture. The mixture was refluxed at 110°C azeotropically (with simultaneously collecting water from the sidearm) for 4 hours to obtain a product mixture. After the reaction was complete (complete removal of water from the mixture), the so obtained product mixture was cooled to 30 oC, and 100 ml of water was added to obtain a biphasic layer containing a toluene layer and an aqueous layer. The toluene layer was separated and washed with water to obtain a separated toluene layer. The separated toluene layer was concentrated by distillation to obtain 2-(heptan-4-ylidene)malononitrile of 98 % purity and 90 % yield.
Example - 3: Preparation of 2-(heptan-4-ylidene)malononitrile using MCB (monochlorobenzene)
4-hepatanone (1.0 mol) and malononitrile (1.05 moles) were mixed in MCB (1000 ml) followed by adding ammonium acetate (0.15 mole) and acetic acid (0.3 moles) at 30oC to obtain a mixture. The mixture was refluxed at 130 °C to 135 °C azeotropically (with simultaneously collecting water from the sidearm) for 4 hours to obtain a product mixture. After the reaction was complete (complete removal of water from the mixture), the so obtained product mixture was cooled to 30 oC, and 100 ml of water was added to obtain a biphasic layer containing MCB layer and an aqueous layer. The MCB layer was separated and washed with water to obtain a separated MCB layer. The separated MCB layer was concentrated by distillation to obtain 2-(heptan-4-ylidene)malononitrile of 98 % purity and 90 % yield.
EXPERIMENT 3:
Step III- Preparation of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile in accordance with the present disclosure
Example- 4:
2-(heptan-4-ylidene)malononitrile (1.0 mole) obtained in experiment 2 and methacroline (1.05 mole) obtained in experiment 1 were mixed in a reactor containing 500 ml of toluene to obtain a mixture. 2.1 m/m of triethylamine (TEA) was added into the mixture and refluxed (112 oC for 10 hours) to obtain a crude product comprising 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile. The crude product comprising 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile was vacuum distilled to obtain 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile having 70 % yield.
EXPERIMENT 4:
Step IV - Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile in accordance with the process of the present disclosure
Example-5: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile by using CaCO3 as base
1 mole of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile obtained in experiment 3 was added in a reactor containing 3 lit of monochlorobenzene (MCB) followed by adding 1.5 moles of CaCO3 at 30oC to obtain a mixture. The mixture was heated to reflux (130 °C to 135°C) to obtain a reaction mixture. Separately, 224gm of bromine was diluted in 500 ml of MCB to obtain a bromine solution. The bromine solution was added to the reaction mixture below the surface at 130 °C to 135 oC over 4 hours under nitrogen flow (inert atmosphere) to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis. After the reaction was complete, the product mixture was filtered to remove the inorganic salt and a filtrate was obtained. The filtrate was washed with water. Finally, MCB was removed by distillation and 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile was vacuum distilled to obtain 70 % yield.
Example-6: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)-malononitrile by using CaCO3 as base
10 gms (46.7 mMoles) of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile obtained in experiment 3 was added in a reactor containing 140 ml of MCB followed by adding 7 gms of CaCO3 under stirring at 30 oC to obtain a mixture. The mixture was heated to reflux (130 oC to135 °C) to obtain a reaction mixture. Separately, 8 gm of Iodine was diluted in 50 ml MCB to obtain an iodine solution (in MCB). The Iodine solution was added to the reaction mixture below the surface at 130 oC to 135 oC over 4 hours under nitrogen flow (inert atmosphere) to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis. The GC analysis shows 80 % product 2-(2,6-Diethyl-4-methyl-phenyl)-malononitrile formation.
Example-7: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile by using Na2CO3 as base
0.1 mole of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile malononitrile obtained in experiment 3 was added in 300 ml of MCB followed by adding 0.15 moles of Na2CO3 at 30oC to obtain a mixture. The mixture was heated to reflux (130 °C to 135 °C) to obtain a reaction mixture. Separately, 22.4 gm of bromine was diluted in 50 ml MCB to obtain a bromine solution. The bromine solution was added to the reaction mixture below the surface at 130 oC to 135 oC over 4 hours under nitrogen flow (inert atmosphere) to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis. The GC analysis shows 84 % product (2-(2,6-diethyl-4-methyl-phenyl)–malononitrile) formation.
Example-8: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile without using base
0.1 mole of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile obtained in experiment 3 was added in 300 ml of MCB at 30 oC to obtain a mixture. The mixture was heated to reflux (130 °C to 135°C) to obtain a reaction mixture. Separately, 22.4 gm of bromine was diluted in 50 ml MCB to obtain a bromine solution. The bromine solution was added to the reaction mixture below the surface at 130 °C to 135 oC over 4 hours under nitrogen flow (inert atmosphere) to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis. The GC analysis shows 80 % product (2-(2,6-diethyl-4-methyl-phenyl)–malononitrile) formation.
Example-9: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile with iodine and bromine without using base
0.1 mole of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile was added in 300 ml of MCB at 30oC to obtain a mixture. The mixture was heated to reflux (130°C to135°C) to obtain a reaction mixture. Separately, 0.015 m iodine and 0.14 m bromine were diluted in 300 ml of MCB to obtain a bromine-iodine solution. The bromine-iodine solution was added to the reaction mixture below the surface at 130 oC to135 oC over 4 hours under nitrogen flow (inert atmosphere) to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis and distilled. The GC analysis shows 66% product (2-(2,6-diethyl-4-methyl-phenyl)–malononitrile) formation.
Examples-10-13: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile
2-(2,6-diethyl-4-methyl-phenyl)–malononitrile were prepared by using 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile similar to the process described in Example 9 by varying the halide concentration, the resultant yields are provided below in Table 1.
Table 1 – Process is same as example 9 except the use of different concentrations of halides
Example Halide mixture MCB lit/m Distilled yield of product
10 2 m % Iodine and 1.4 m/m Bromine 3 lit/m MCB 56 %
11 5 m % Iodine and 1.4 m/m Bromine 3 lit/m MCB 51 %
12 10 m % Iodine and 1.4 m/m Bromine 3 lit/m MCB 60 %
13 20 m % Iodine and 1.4 m/m Bromine 3 lit/m MCB 61 %

Example-14: Preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile using nitro derivatives
0.4 mole of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile was added in 300 ml of ortho dichlorobenzene (ODCB) at 30 oC to obtain a mixture in nitrogen as an inert atmosphere. The mixture was heated to reflux (180 °C to190 °C) to obtain a reaction mixture. 148 gm of nitrobenzene was added over a period of 4 hours uniformly at reflux to obtain a product mixture comprising 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The reaction progress was monitored by GC analysis and worked up till no further conversion was observed by GC analysis. The product mixture was subjected to vacuum distillation to obtain 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile. The yield of the product (2-(2,6-diethyl-4-methyl-phenyl)–malononitrile) was 38%.

TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of the process of the preparation of 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile that;
- avoids palladium;
- uses easily available and comparatively cheap raw materials hence the process is economical;
- the halide used during the process is recovered and reused and hence the process is economical and environment friendly;
- a simple and environment friendly process for preparing 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile; and
- provides 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile in comparatively high purity and high yield.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
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.
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 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.
,CLAIMS:WE CLAIM:
1. A process for preparing 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile, said process comprising the following steps:
a) reacting paraformaldehyde with propanaldehyde by using a first base at a temperature in the range of 70 °C to 100 °C for a time period in the range of 2 hours to 5 hours to obtain methacrolein;
b) separately, reacting 4-heptanone with malononitrile in a first fluid medium by using a second base at a temperature in the range of 100 °C to 140 °C for a time period in the range of 2 hours to 6 hours to obtain 2-(heptan-4-ylidene)malononitrile;
c) reacting the methacrolein obtained in step (a) with 2-(heptan-4-ylidene)malononitrile obtained in step (b) by using a third base in a second fluid medium at a temperature in the range of 100 °C to 140 °C for a time period in the range of 8 hours to 20 hours to obtain 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile; and
d) reacting 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile with a halide in a third fluid medium optionally by using a fourth base in an inert atmosphere at a temperature in the range of 120 oC to 140 oC to obtain 2-(2,6-diethyl-4-methyl-phenyl)–malononitrile.
2. The process as claimed in claim 1, wherein said first base is at least one selected from morpholine and diethanolamine.
3. The process as claimed in claim 1, wherein said first fluid medium is at least one selected from toluene, monochlorobenzene (MCB), and dichlorobenzene.
4. The process as claimed in claim 1, wherein said second base is a weak base.
5. The process as claimed in claim 4, wherein said weak base is ammonium acetate.
6. The process as claimed in claim 1, wherein said third base is selected from trimethylamine, triethylamine and tributylamine.
7. The process as claimed in claim 1, wherein said second fluid medium is at least one selected from toluene and monochlorobenzene (MCB).
8. The process as claimed in claim 1, wherein said halide is at least one selected from bromine solution, iodine solution, and solid iodine.
9. The process as claimed in claim 1, wherein said third fluid medium is at least one selected from monochlorobenzene (MCB), bromobenzene, nitrobenzene, and orthodichlorobenzene.
10. The process as claimed in claim 1, wherein said inert atmosphere is selected from nitrogen and argon.
11. The process as claimed in claim 1, wherein said fourth base is selected from calcium carbonate and sodium carbonate.
12. The process as claimed in claim 1, wherein a molar ratio of the propanaldehyde to the paraformaldehyde in step a) is in the range of 1:0.9 to 1:1.2.
13. The process as claimed in claim 1, wherein a mole ratio of 2-(2,6-diethyl-4-methyl-hexylidene)-malononitrile to the fourth base in step d) is in the range of 1:1 to 1:2.

Dated this 08th day of September, 2021

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant
TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI