DESC:FIELD
The present disclosure relates to a process for the preparation of cypermethrin intermediate.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Cypermethrin is a synthetic pyrethroid used as an insecticide in large-scale commercial agricultural applications as well as in consumer products for domestic purposes. Conventional methods for preparation of cypermethrin generally follows the following route:

2,4,4,4-tetrachlorobutyronitrile (TBN) is used as a starting material for the preparation of Cypermethrin. 2,4,4,4-tetrachlorobutyronitrile (TBN) [CAS No. 41797-95-9] is represented as follows

Conventional methods for synthesis of 2,4,4,4-tetrachlorobutyronitrile (TBN) involves use carbon tetrachloride (CTC) as a starting material, the method is represented as given below:

However, CTC is covered under Ozone depleting substance (ODS), due to it’s ozone depleting properties. Therefore, use of carbon tetrachloride (CTC) as feedstock is restricted under Montreal protocol.
There is, therefore, felt a need to provide an alternative process for the preparation of cypermethrin intermediate, which is simple, economical 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 a process for the preparation of cypermethrin intermediate.
Another object of the present disclosure is to provide a simple, economical and environment-friendly process for the preparation of cypermethrin intermediate.
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.
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, well-known processes, well-known apparatus 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 is 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.
The present disclosure provides a simple, economical and environment-friendly process for the preparation of cypermethrin intermediate having a general formula represented by:

Formula I
wherein,
X is selected from CN, COOH, COCl, COOR, wherein R is selected from C1 to C10 alkyl.
In one embodiment of the present disclosure, the cypermethrin intermediate is 2,4,4,4-tetrachlorobutyronitrile (TBN) represented by Formula IA, when X is CN.

Formula IA
In another embodiment of the present disclosure, the cypermethrin intermediate is 2,4,4,4-tetrachlorobutyric acid (TBA), represented by Formula IB, when X is COOH.

Formula IB
In still another embodiment of the present disclosure, the cypermethrin intermediate is 2,4,4,4-tetrachlorobutyric acid chloride (TBAc), represented by Formula IC, when X is COCl.

Formula IC
In yet another embodiment of the present disclosure, the cypermethrin intermediate obtained is 2,4,4,4-tetrachlorobutyric acid ester (TBA ester), represented by Formula ID, when X is COOR.

Formula ID
wherein, R is selected from C1 to C10 alkyl.
Preparation of the cypermethrin intermediate formula (I), in accordance with the process of the present disclosure, is shown as Scheme I given below:
Scheme I:

The process of the present disclosure involves a simple synthesis of the cypermethrin intermediate formula (I) comprising the following sub-steps.
• chlorinating carbon di-sulfide (II) using a chlorinating agent in a first fluid medium, at a temperature in the range of 10 to 40 °C to obtain trichloromethane sulfenyl chloride (III);
• oxidizing trichloromethane sulfenyl chloride (III) by using an oxidizing agent in the presence of a first catalyst, in a second fluid medium, at a temperature in the range of 20 °C to 110 °C to obtain trichloromethane sulfonyl chloride (IV); and
• reacting trichloromethane sulfonyl chloride (IV) with an acryl derivative (V) selected from acrylonitrile, acrylic acid, alkyl acrylate and acryloyl chloride, in the presence of a second catalyst and a base in a third fluid medium, at a temperature in the range of 100 to 130 °C to obtain cypermethrin intermediate of Formula I.
The process is described in detail herein below:
Step-I: Chlorination of carbon di-sulfide (II) using a chlorinating agent to obtain trichloromethane sulfenyl chloride (III) is illustrated as:

Chlorination of carbon di-sulfide (II) is carried out using a chlorinating agent in a first fluid medium, at a temperature in the range of 10 to 40 °C, to obtain trichloromethane sulfenyl chloride (III).
The chlorinating agent is chlorine gas.
The first fluid medium is the acidic medium. Typically, the first fluid medium is an aqueous solution of hydrochloric acid, wherein the concentration of hydrochloric acid is in the range of 2 N to 4 N.
Typically, when chlorinating agent is chlorine gas, the chlorination of carbon di-sulfide (II) is carried out by passing the chlorine gas through the solution of carbon di-sulfide in the aqueous hydrochloric acid at a flow rate in the range of 0.1 to 0.8 m/m/hr.
In accordance with an exemplary embodiment of the present disclosure, the reactor is charged with carbon di-sulfide (II) and 3N aqueous hydrochloric acid to obtain a first reaction mixture. The first reaction mixture is cooled to a temperature in the range of 20 to 26 °C. The chlorine gas is then passed through the first reaction mixture at the flow rate of 0.05 m/m/hr for 6 to 8 hours to obtain a first resultant mixture.
Work up- After completion of reaction (monitored by gas chromatography), the first resultant mixture is allowed to settle to obtain a first bi-phasic mixture. The first organic layer is separated from the first bi-phasic mixture and washed with cold water to obtain trichloromethane sulfenyl chloride (III).
Step-II: Oxidation of trichloromethane sulfenyl chloride (III) to trichloromethane sulfonyl chloride (IV) is illustrated as:

Oxidation of trichloromethane sulfenyl chloride (III) to trichloromethane sulfonyl chloride (IV) is carried out by using an oxidizing agent in the presence of a first catalyst, in a second fluid medium, at a temperature in the range of 20 °C to 110 °C.
The oxidizing agent is selected from chlorine gas in aqueous medium, hydrogen peroxide and calcium hypochlorite.
The second fluid medium is selected from water and acetic acid.
In an embodiment of the present disclosure, when the oxidizing agent is chlorine gas, the second fluid medium is water and the oxidation of trichloromethane sulfenyl chloride (III) is carried at a temperature in the range of 25 °C to 40 °C.
In another embodiment of the present disclosure, when the oxidizing agent is hydrogen peroxide, the second fluid medium is acetic acid and the oxidation of trichloromethane sulfenyl chloride (III) is carried at a temperature in the range of 90 °C to 110 °C.
Typically, when the oxidizing agent is chlorine gas, the oxidation of trichloromethane sulfenyl chloride (III) is carried out by passing the chlorine gas through the solution of trichloromethane sulfenyl chloride (III) in water at a flow rate in the range of 0.1 to 1.2 m/m/hr.
The first catalyst is phospho-tungstic acid. The molar ratio of trichloromethane sulfenyl chloride to the first catalyst is in the range of 1: 0.00010 to 1: 0.00170. In an exemplary embodiment of the present disclosure, the molar ratio of trichloromethane sulfenyl chloride to the first catalyst is 1: 0.00035.
In an exemplary embodiment of the present disclosure, the reactor is charged with trichloromethane sulfenyl chloride (III), water and phospho-tungstic acid to obtain a second reaction mixture. The chlorine gas is then passed through the second reaction mixture under continuous stirring at a flow rate in the range of 0.1 to 1.2 m/m/hr over a time period of 12 hr and at a temperature in the range of 48 to 50°C to obtain slurry.
Typically, during the first 1 to 4 hours, Cl2 gas is passed at a flow rate of 0.25 m/m/hr. Further, during 5 to 8 hours, Cl2 gas is passed at a flow rate of 0.20 m/m/hr. Furthermore, during 9 to 12 hours, Cl2 gas is passed at a flow rate of 0.15 m/m/hr.
In accordance with the present disclosure, the excess chlorine gas is removed using 4N scrubber (4N NaOH solution).
Work up- After completion of the reaction (monitored by gas-liquid chromatography), the slurry is cooled to room temperature. Carbon tetra-chloride is added to the cooled slurry and stirred for a time period in the range of 10 to 20 minutes to obtain a solution. The solution is allowed to settle to obtain a second bi-phasic mixture. The organic layer is separated from the second bi-phasic mixture and washed with water to obtain a washed organic layer. Water is then added to the washed organic layer, followed by addition of sodium bi-carbonate solution in order to adjust the pH of the resultant bi-phasic mixture in the range 7 to 8. The organic layer is separated from the resultant bi-phasic mixture and heated at a temperature in the range of 50 to 70 °C. Sodium hypochlorite solution is added to the heated organic layer and stirred for time period in the range of 1 to 4 hours. The organic layer is then separated from the sodium hypochlorite solution and directly used in the next step.
Step-III: Reaction of trichloromethane sulfonyl chloride (IV) with an acryl derivative to obtain cypermethrin intermediate (I) is illustrated as:

Reaction of trichloromethane sulfonyl chloride (IV) with an acryl derivative (V) selected from acrylonitrile, acrylic acid, alkyl acrylate and acryloyl chloride, is carried out in the presence of a second catalyst and a base in a third fluid medium, at a temperature in the range of 100 to 130 °C to obtain cypermethrin intermediate of Formula I.
The second catalyst is selected from copper salt, and iron salt. Typically, the second catalyst is copper salt. In accordance with an exemplary embodiment of the present disclosure, the second catalyst is copper chloride. The molar ratio of trichloromethane sulfonyl chloride to the second catalyst is in the range of 1: 0.1 to 1: 2.0.
The base is diethyl amine. The organic amine forms a complex with a catalyst, which helps in increasing its catalytic activity. The molar ratio of trichloromethane sulfonyl chloride to the base is in the range of 1: 0.1 to 1: 2.0. In an exemplary embodiment of the present disclosure, the molar ratio of trichloromethane sulfonyl chloride to the base is 1: 1.5.
The third fluid medium is at least one selected from acetonitrile and carbon tetrachloride. Typically, the third fluid medium is a combination of acetonitrile and carbon tetrachloride, wherein the molar ratio of acetonitrile to carbon tetrachloride is 1: 0.1. The present disclosure involves use of carbon tetrachloride as co-solvent and the amount of carbon tetrachloride used is very low, thereby making the process environment friendly.
In accordance with an exemplary embodiment of the present disclosure, the reactor is charged with acetonitrile and carbon tetrachloride. The base and the second catalyst are added to the reactor to obtain a mixture. Nitrogen gas is flushed through the mixture and the mixture is heated at a temperature in the range of 115 to 125 °C. Trichloromethane sulfonyl chloride (IV) and an acryl derivative (V) are added to the heated mixture simultaneously over a time period of 4 to 8 hours to obtain a third reaction mixture. Sulphur dioxide gas is evolved from the mixture, during addition of trichloromethane sulfonyl chloride (IV) and an acryl derivative (V). The third reaction mixture is further heated to a temperature in the range of 115 to 125 °C for 6 to 12 hours and still further heated to a temperature in the range of 125 to 135 °C for 5 to 10 hours to obtain a product mixture.
Work-up: The product mixture is subjected to distillation at a temperature in the range of 110 to 120 °C and at 20 mmHg pressure to remove the third fluid medium (acetonitrile and carbon tetrachloride). The separated third fluid medium is recycled to the next batch.
The residual product mixture is cooled to room temperature and filtered to remove the catalyst, which is recycled to the next batch.
The filtrate obtained is further subjected to distillation at a temperature in the range of 115 to 125 °C and at 2 mmHg pressure to obtain the cypermethrin derivative of Formula I.
In one embodiment of the present disclosure, the trichloromethane sulfonyl chloride (IV) is reacted with acrylonitrile (V) and the cypermethrin intermediate obtained is 2,4,4,4-tetrachlorobutyronitrile (TBN) represented by Formula IA:

Formula IA
In another embodiment of the present disclosure, the trichloromethane sulfonyl chloride (IV) is reacted with acrylic acid (V) and the cypermethrin intermediate obtained is 2,4,4,4-tetrachlorobutyric acid (TBA), represented by Formula IB:

Formula IB
In still another embodiment of the present disclosure, the trichloromethane sulfonyl chloride (IV) is reacted with acryloyl chloride (V) and the cypermethrin intermediate obtained is 2,4,4,4-tetrachlorobutyric acid chloride (TBAc), represented by Formula IC:

Formula IC
In yet another embodiment of the present disclosure the trichloromethane sulfonyl chloride (IV) is reacted with acrylic acid ester (V) and the cypermethrin intermediate obtained is 2,4,4,4-tetrachlorobutyric acid ester (TBA ester), represented by Formula ID:

Formula ID
wherein, R is selected from C1 to C10 alkyl.
In accordance with the present disclosure, sulphur di-oxide (SO2) formed during the reaction of trichloromethane sulfonyl chloride with acrylic derivative can be recovered and used in other reactions.
The process of the present disclosure is simple and employs inexpensive and easily available reagents. Thus, the process of the present disclosure is economical. Further, the process of the present disclosure obviates use of carbon tetrachloride (CTC), thereby making the process environment-friendly. Furthermore, the process of the present disclosure provides an alternate method for direct synthesis of cypermethrin intermediates.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
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.
EXPERIMENTAL DETAILS
Example 1: Preparation of 2,4,4,4-tetrachlorobutyronitrile (TBN) (IA) in accordance with the present disclosure
Step-I: Chlorination of carbon di-sulfide (II) using a chlorinating agent to obtain trichloromethane sulfenyl chloride (III)
The reactor was charged with carbon di-sulfide (II) (1 mole) and 3N aqueous hydrochloric acid (666 mL) to obtain a first reaction mixture. The first reaction mixture was cooled 25 °C. The chlorine gas was then passed through the first reaction mixture at the flow rate of 0.05 m/m/hr for 6 hours to obtain a first resultant mixture.
Work up- After completion of reaction (monitored by gas chromatography), the first resultant mixture was allowed to settle to obtain a first bi-phasic mixture. The first organic layer is separated from the first bi-phasic mixture and washed with cold water to obtain trichloromethane sulfenyl chloride (III).
The gas chromatographic analysis of the trichloromethane sulfenyl chloride: CS2= 0.5% CCl3SCl 97% and CCl3SO2Cl= 1.732%.
Trichloromethane sulfenyl chloride obtained was used without any further purification.
Step-II: Oxidation of trichloromethane sulfenyl chloride (III) to trichloromethane sulfonyl chloride (IV)
The reactor was charged with trichloromethane sulfenyl chloride (III) (1 mole), water (500 mL) and phospho-tungstic acid (1.0 gm, 0.00035 moles) to obtain a second reaction mixture. The chlorine gas was then passed through the second reaction mixture under continuous stirring for 12 hr and at a temperature in the range of 48 to 50°C to obtain a resultant mixture. The flow rate of the chlorine gas was maintained as follows:
1 to 4 hours, Cl2 gas flow rate was 0.25 m/m/hr;
5 to 8 hours, Cl2 gas flow rate was 0.20 M/M/Hr; and
9 to 12 hours, Cl2 gas flow rate was 0.15 M/M/Hr.
Excess Cl2 was removed from the reaction mixture using 4N NaOH solution as a scrubber.
After 12 hours, the resultant mixture was stirred at 50°C with continuous nitrogen purging to remove all dissolved unreacted Cl2 gas to obtain slurry. The gas-liquid chromatography of the slurry provided following results:
Total Cl2 m/m CCl4 CCl3SCl CCl3SO2Cl Imp.
2.4 4-6% 4-6% 86-89% <1%

Work up- After completion of the reaction (monitored by gas-liquid chromatography), the slurry was cooled to room temperature. Carbon tetra-chloride (250 mL/mole of trichloromethane sulfenyl chloride (III)) was added to the cooled slurry and stirred for 20 minutes to obtain a solution. The solution was allowed to settle to obtain a second bi-phasic mixture. The organic layer was separated from the a second bi-phasic mixture and washed with water to obtain a washed organic layer. Water (100 mL/ mole of trichloromethane sulfenyl chloride (III)) was then added to the washed organic layer, followed by addition of sodium bi-carbonate solution to adjust the pH of the resultant bi-phasic mixture in the range 7 to 8. The organic layer was separated from the resultant bi-phasic mixture and heated at 60 °C. Sodium hypochlorite solution (0.4 moles/ mole of trichloromethane sulfenyl chloride (III)) was added to the heated organic layer and stirred for 3 hours. The organic layer was then separated from the sodium hypochlorite solution and directly used for the further step.
The gas-liquid chromatographic analysis of organic layer is:
CCl3SCl CCl3SO2Cl Imp.
<0.5% 98-98.5% <1%

Step-III: Reaction of trichloromethane sulfonyl chloride (IV) with acrylonitrile (V) to obtain 2,4,4,4-tetrachlorobutyronitrile (IA)
The reactor was charged with acetonitrile and carbon tetrachloride (20 g/m). Diethyl amine hydrochloride (0.01 moles) and hydrated copper chloride (0.02 moles) were added to the reactor to obtain a mixture. Nitrogen gas was flushed through the mixture and the mixture was heated to 120 °C. Trichloromethane sulfonyl chloride (IV) (1.45 m) and an acrylonitrile (V) (1 m) were added to the heated mixture simultaneously over a time period of 6 hours to obtain a third reaction mixture. Sulphur dioxide gas evolved after addition, was scrubbed using alkali scrubber. The third reaction mixture was successively heated at 118 °C for 8 hours and at 130 °C for 6 hours to obtain a product mixture.
Work-up: The product mixture was subjected to distillation at 115 °C and at 20 mmHg pressure to remove acetonitrile and carbon tetrachloride.
The residual product mixture was cooled to room temperature and filtered to remove copper chloride.
The filtrate was further subjected to distillation at 115 °C and at 2 mmHg pressure to obtain 2,4,4,4-tetrachlorobutyronitrile (IA). The yield of 2,4,4,4-tetrachlorobutyronitrile (IA) was 86%.
Example 2: Preparation of 2,4,4,4-tetrachlorobutyric acid (TBA) (IB) in accordance with the present disclosure
Step I and Step II were carried out by the similar procedure disclosed in example 1.
Step-III: Reaction of trichloromethane sulfonyl chloride (IV) with acrylic acid (V) to obtain 2,4,4,4-tetrachlorobutyric acid (IB)
The reactor was charged with acetonitrile and carbon tetrachloride (2 g/m). Diethyl amine hydrochloride (0.01 m/m) and hydrated copper chloride (0.02 m/m) were added to the reactor to obtain a mixture. Nitrogen gas was flushed through the mixture and the mixture was heated at 120 °C. Trichloromethane sulfonyl chloride (IV) (1.45 m) and an acrylic acid (V) (1 m) were added to the heated mixture simultaneously over a time period of 6 hours to obtain a third reaction mixture. Sulphur dioxide gas evolved after addition, was scrubbed using alkali scrubber. The third reaction mixture was successively heated at 118 °C for 8 hours and at 130 °C for 6 hours to obtain a product mixture.
Work-up: The product mixture was subjected to distillation at 115 °C and at 20 mmHg pressure to remove acetonitrile and carbon tetrachloride.
The residual product mixture was cooled to room temperature and filtered to remove copper chloride.
The filtrate was further subjected to distillation at 115 °C and at 2 mmHg pressure to obtain 2,4,4,4-tetrachlorobutyric acid (IB). The yield of 2,4,4,4-tetrachlorobutyric acid (IB) was 76%.
Example 3: Preparation of 2,4,4,4-tetrachlorobutyric acid chloride (IC) in accordance with the present disclosure
Step I and Step II were carried out by the similar procedure disclosed in example 1.
Step-III: Reaction of trichloromethane sulfonyl chloride (IV) with acrloyl chloride (V) to obtain 2,4,4,4-tetrachlorobutyric acid chloride (IC)
The reactor was charged with acetonitrile and carbon tetrachloride (20 g/m). Diethyl amine hydrochloride (0.01 m/m) and hydrated copper chloride (0.02 m/m) were added to the reactor to obtain a mixture. Nitrogen gas was flushed through the mixture and the mixture was heated at 120 °C. Trichloromethane sulfonyl chloride (IV) (1.45 m) and an acrloyl chloride (V) (1 m) were added to the heated mixture simultaneously over a time period of 6 hours to obtain a third reaction mixture. Sulphur dioxide gas evolved after addition, was scrubbed using alkali scrubber. The third reaction mixture was successively heated at 118 °C for 8 hours and at 130 °C for 6 hours to obtain a product mixture.
Work-up: The product mixture was subjected to distillation at 115 °C and at 20 mmHg pressure to remove acetonitrile and carbon tetrachloride.
The residual product mixture was cooled to room temperature and filtered to remove copper chloride.
The filtrate was further subjected to distillation at 115 °C and at 2 mmHg pressure to obtain 2,4,4,4-tetrachlorobutyric acid chloride (IC). The yield of 2,4,4,4-tetrachlorobutyric acid chloride (IC) was 60%.
Example 4: Preparation of 2,4,4,4-tetrachlorobutyric acid methyl ester (ID) in accordance with the present disclosure
Step I and Step II were carried out by the similar procedure disclosed in example 1.
Step-III: Reaction of trichloromethane sulfonyl chloride (IV) with methyl acrylate (V) to obtain 2,4,4,4-tetrachlorobutyric acid methyl ester (ID)
The reactor was charged with acetonitrile and carbon tetrachloride (20 g/m). Diethyl amine hydrochloride (0.01 m/m) and hydrated copper chloride (0.02 m/m) were added to the reactor to obtain a mixture. Nitrogen gas was flushed through the mixture and the mixture was heated at 120 °C. Trichloromethane sulfonyl chloride (IV) (1.45 m) and methyl acrylate (V) (1 m) were added to the heated mixture simultaneously over a time period of 6 hours to obtain a third reaction mixture. Sulphur dioxide gas evolved after addition, was scrubbed using alkali scrubber. The third reaction mixture was successively heated at 118 °C for 8 hours and at 130 °C for 6 hours to obtain a product mixture.
Work-up: The product mixture was subjected to distillation at 115 °C and at 20 mmHg pressure to remove acetonitrile and carbon tetrachloride.
The residual product mixture was cooled to room temperature and filtered to remove copper chloride.
The filtrate was further subjected to distillation at 115 °C and at 2 mmHg pressure to obtain 2,4,4,4-tetrachlorobutyric acid methyl ester (ID). The yield of 2,4,4,4-tetrachlorobutyric acid methyl ester (ID) was 75%.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a process for the preparation of cypermethrin intermediate, which:
- is simple, economical and environment-friendly process; and
- obviates use of the carbon tetrachloride (CTC) as starting material.
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 preparation of cypermethrin intermediate, having a general formula represented as:

Formula I
wherein,
X is selected from CN, COOH, COCl, COOR, wherein R is selected from C1 to C10 alkyl;
said process comprising the following steps:
i. chlorinating carbon di-sulfide using a chlorinating agent in a first fluid medium, at a temperature in the range of 10 to 40 °C to obtain trichloromethane sulfenyl chloride;
ii. oxidizing trichloromethane sulfenyl chloride by using an oxidizing agent in the presence of a first catalyst, in a second fluid medium, at a temperature in the range of 25 °C to 110 °C to obtain trichloromethane sulfonyl chloride; and
iii. reacting trichloromethane sulfonyl chloride with an acrylic derivative selected from acrylonitrile, acrylic acid, alkyl acrylate and acryloyl chloride, in the presence of a second catalyst and a base in a third fluid medium, at a temperature in the range of 100 to 130 °C to obtain cypermethrin intermediate of Formula I.
2. The process as claimed in claim 1, wherein said cypermethrin intermediate of Formula I is 2,4,4,4-tetrachlorobutyronitrile (TBN), represented as Formula IA

when, said acrylic derivative used in step (iii) is acrylonitrile.
3. The process as claimed in claim 1, wherein said cypermethrin intermediate of Formula I is 2,4,4,4-tetrachlorobutyric acid (TBA), represented as Formula IB

when, said acrylic derivative used in step (iii) is acrylic acid.
4. The process as claimed in claim 1, wherein said cypermethrin intermediate of Formula I is 2,4,4,4-tetrachlorobutyric acid chloride (TBA chloride), represented as Formula IC

when, said acrylic derivative used in step (iii) is acryloyl chloride.
5. The process as claimed in claim 1, wherein said cypermethrin intermediate of Formula I is 2,4,4,4-tetrachlorobutyric acid ester (TBA ester), represented as Formula ID

when, R is selected from C1 to C10 alkyl; and
wherein, said acrylic derivative used in step (iii) is alkyl acrylate.
6. The process as claimed in claim 1, wherein said chlorinating agent is chlorine gas.
7. The process as claimed in claim 1, wherein said first fluid medium is an aqueous solution of hydrochloric acid, wherein the concentration of the hydrochloric acid is in the range of 2 N to 4 N.
8. The process as claimed in claim 1, wherein said step (i) of chlorination is carried out by passing the chlorine gas through the solution of carbon di-sulfide in said first fluid medium at a flow rate in the range of 0.1 to 0.8 m/m/hr.
9. The process as claimed in claim 1, wherein said oxidizing agent is selected from chlorine gas, hydrogen peroxide and calcium hypochlorite.
10. The process as claimed in claim 1, wherein said first catalyst is phospho-tungstic acid and the molar ratio of trichloromethane sulfenyl chloride to said first catalyst is in the range of 1: 0.00010 to 1: 0.00170.
11. The process as claimed in claim 1, wherein said second fluid medium is at least one selected from water and acetic acid.
12. The process as claimed in claim 1, wherein the said (ii) of oxidation is carried out by passing the chlorine gas through the solution of trichloromethane sulfenyl chloride in said second fluid medium at a flow rate in the range of 0.1 to 1.2 m/m/hr.
13. The process as claimed in claim 1, wherein said second catalyst is selected from copper salt, and iron salt; and wherein the molar ratio of trichloromethane sulfonyl chloride to said second catalyst is in the range of 1: 0.1 to 1: 2.0.
14. The process as claimed in claim 1, wherein said base is diethyl amine; and wherein the molar ratio of trichloromethane sulfonyl chloride to said base is in the range of 1: 0.1 to 1: 2.0.
15. The process as claimed in claim 1, wherein said third fluid medium is at least one selected from acetonitrile and carbon tetrachloride.