DESC:FIELD
The present disclosure relates to a process for preparing cartap hydrochloride.
BACKGROUND
Cartap is a thiocarbamate insecticide, having the chemical formula -C7H16ClN3O2S2 [CAS No. 15263-53-3]. It is commonly used as the hydrochloride (Cartap hydrochloride: C7H15N3O2S3HCl). It is essentially a contact insecticide and is highly effective against both chewing and sucking pests, resulting in paralysis. Cartap hydrochloride is categorized as an effective, relatively low-toxic, and low-residue insecticide.
Cartap hydrochloride is in high demand because of its broad spectrum activity. Conventional processes for the preparation of cartap hydrochloride are associated with disadvantages such as low yield and low purity.
There is, therefore, felt a need to provide an efficient process for preparing cartap hydrochloride in high yield and with high purity.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a process for preparation of cartap hydrochloride.
Another object of the present disclosure is to provide a process for preparation of cartap hydrochloride in high yield and with high purity.
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
In one aspect the present disclosure provides a process for preparing cartap hydrochloride. The process of the present disclosure comprises the following steps.
Amination of allyl chloride is carried out with dimethylamine in the presence of at least one base to obtain N,N-dimethylallylamine.
Hydrochloride salt of N,N-dimethylallylamine is formed using hydrogen chloride gas. N,N-dimethylallylamine hydrochloride is chlorinated using chlorine gas to obtain 2,3-dichloro-N-N-dimethylpropylamine hydrochloride.
2,3-Dichloro-N-N-dimethylpropylamine hydrochloride is reacted with sodium thiosulfate to obtain a mixture containing monosodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (monosultap) and disodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (bisultap).
A first fraction comprising monosultap and a second fraction comprising bisultap are separated from the mixture.
Cyanation of the first fraction comprising monosultap is carried out using at least one alkali metal cyanide in the presence of at least one base to obtain a first portion of dithiocyanato compound. The first portion of dithiocyanato compound is hydrolyzed with hydrogen chloride gas in the presence of at least one alcohol to obtain a first crop of cartap hydrochloride.
Cyanation of the second fraction comprising bisultap is carried out using at least one alkali metal cyanide in the presence of at least one base to obtain a second portion of dithiocyanato intermediate. The second portion of dithiocyanato compound is hydrolyzed with hydrogen chloride gas in the presence of at least one alcohol to obtain a second crop of cartap hydrochloride.
The first crop of cartap hydrochloride and the second crop of cartap hydrochloride are mixed to obtain cartap hydrochloride.
The base is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.
In accordance with the first embodiment of the present disclosure, the step of reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate involves neutralizing 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with at least one base followed reacting the neutralized mass with sodium thiosulfate by adding sodium thiosulfate in one portion.
In accordance with the second embodiment of the present disclosure, the step of reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate involves addition of sodium thiosulfate to 2,3-dichloro-N-N-dimethylpropylamine hydrochloride in two to five portions.
The alkali metal cyanide is at least one selected from the group consisting of sodium cyanide, and potassium cyanide.
The alcohol is at least one selected from the group consisting of methanol, and ethanol.
Cartap hydrochloride is obtained by the process of the present disclosure with a yield 55% to 75%, and with purity in the range of 95% to 99.5%.

DETAILED DESCRIPTION
Conventional processes for the preparation of cartap hydrochloride are associated with disadvantages such as low yield and low purity. The present disclosure envisages an efficient process for preparing cartap hydrochloride in high yield and with high purity.
In one aspect, the present disclosure provides a process for preparing cartap hydrochloride. The process of the present disclosure comprises the following steps.
Step-1: Amination

Amination of allyl chloride is carried out with dimethylamine in the presence of at least one base to obtain N,N-dimethylallylamine.
Dimethylamine is in the form of an aqueous solution. In accordance with one embodiment of the present disclosure, the concentration of the aqueous solution of dimethyl amine is 7.5 N.
Amination is carried out at a temperature in the range of 25 ?C to 70 ?C.
Step-2: Hydrochloride salt and Chlorination

Hydrochloride salt of N,N-dimethylallylamine is formed using hydrogen chloride gas. N,N-dimethylallylamine hydrochloride is chlorinated using chlorine gas to obtain 2,3-dichloro-N-N-dimethylpropylamine hydrochloride.
Step-2 is carried out in the presence of at least one chlorinated fluid medium selected from the group consisting of methylene dichloride, ethylene dichloride, and chloroform.
Step-2 involves removal of water by azeotropic distillation.
Step-3

2,3-Dichloro-N-N-dimethylpropylamine hydrochloride is reacted with sodium thiosulfate to obtain a mixture containing monosodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (monosultap) and disodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (bisultap).
The step of reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate is carried out at a temperature in the range of 50 ?C to 75 ?C.
In accordance with the first embodiment of the present disclosure, the step of reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate involves neutralizing 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with at least one base followed reacting the neutralized mass with sodium thiosulfate by adding sodium thiosulfate in one portion.
In accordance with the second embodiment of the present disclosure, the step of reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate involves addition of sodium thiosulfate to 2,3-dichloro-N-N-dimethylpropylamine hydrochloride in two to five portions.
The reaction of 2,3-Dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate is carried out in at least one alcohol as a fluid medium. The reaction involves heating at refluxing temperature of the alcohol for a period in the range of 2 hours to 20 hours to obtain a product mixture containing monosultap and bisultap in alcohol as a fluid medium.
A first fraction comprising monosultap and a second fraction comprising bisultap are separated from the mixture.
The separation of monosultap from the product mixture containing monosultap and bisultap in alcohol as fluid medium is carried out at pH in the range of 4.0 to 5.0.
Step-4

Cyanation of the first fraction comprising monosultap is carried out with at least one alkali metal cyanide in the presence of at least one base to obtain a first portion of dithiocyanato compound.
Step-5

The first portion of dithiocyanato compound is hydrolyzed with hydrogen chloride gas in the presence of at least one alcohol to obtain a first crop of cartap hydrochloride.
Cyanation of the second fraction comprising bisultap is carried out using at least one alkali metal cyanide in the presence of at least one base to obtain a second portion of dithiocyanato intermediate. The second portion of dithiocyanato compound is hydrolyzed with hydrogen chloride gas in the presence of at least one alcohol to obtain a second crop of cartap hydrochloride.
Cyanation is carried out in the presence of water as fluid medium. Cyanation is carried out at a temperature in the range of 5 ?C to 25 ?C.
Hydrolysis is carried out at temperature in the range of 20 ?C to 70 ?C.
The first crop of cartap hydrochloride and the second crop of cartap hydrochloride are mixed to obtain cartap hydrochloride.
The base is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.
The alkali metal cyanide is at least one selected from the group consisting of sodium cyanide, and potassium cyanide.
The alcohol is at least one selected from the group consisting of methanol, and ethanol.
In the process of the present disclosure cartap hydrochloride is obtained with a yield in the range of 55% to 75%, and with a purity in the range of 95% to 99.5%
In the process of the present disclosure, the mixture containing monosultap and bisultap is separated to obtain a first fraction comprising monosultap and a second fraction comprising bisultap.
The separated fractions are separately converted to cartap hydrochloride. It is observed that if the mixture containing bisultap and monosultap is directly converted to cartap hydrochloride, a low yield of cartap hydrochloride is obtained. The low yield is due to the presence of impurities in the mixture containing bisultap and monosultap that increase the solubility of cartap hydrochloride in the reaction mixture. Further, the isolation of cartap hydrochloride from the mother liquor is very difficult.
Further, even though, the process steps for preparing cartap hydrochloride from monosultap and bisultap are the same, a difference in the yield of cartap hydrochloride is observed.
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.
Experiment:
Experiment I: Preparation of cartap hydrochloride
Step-1: Preparation of N,N-dimethylallylamine (DMAA)
160 ml of aqueous dimethylamine (DMA) (7.5 N solution) was charged to a reactor. 76.5 gm of allyl chloride, and 56 ml of NaOH (18 N NaOH) was simultaneously added to the reactor over a period of 3 hours at 30 °C to obtain a reaction mixture, followed by stirring the reaction mixture at 30°C for 2 hours. Temperature of the reaction mixture was raised to 40°C, followed by stirring for 2 hours. Finally, temperature of the reaction mixture was raised to 55°C, followed by stirring for 4 hours to obtain a product mixture. The product mixture was distilled to obtain N,N,-dimethylallylamine (weight = 75 gm, GLC purity = 99%).

Step-2: Preparation of 2,3-dichloro-N-N-dimethylpropylamine (DCDMPA)
300 ml of methylene dichloride (MDC) was charged to a reactor and 85 gm of N,N,-dimethylallylamine obtained in step-1 was added to the reactor. The resultant mixture was heated to refluxing temperature while water was azeotropically removed. The resultant mass was cooled to 15°C. 40 gm of dry HCl gas was passed into the reaction mass at 15°C followed by stirring for 30 minutes to get a reaction mass containing hydrochloride salt of DMA. Temperature of the reaction mass was raised to 25°C. 85 gm of chlorine gas was passed through the reaction mass at 25 °C followed by stirring for 2 hours. The resultant mass was heated at refluxing temperature while water was azeotropically removed. Resultant reaction mixture was cooled to 10°C, and 75 ml of water was added, followed by stirring for 30 minutes, and the resultant mass was allowed to settle for 30 minutes to obtain a biphasic mixture containing an organic layer and an aqueous layer. Aqueous layer containing 2,3-dichloro-N-N-dimethylpropylamine was separated. Yield of 2,3-dichloro-N-N-dimethylpropylamine was 94%.

Step-3: Preparation of mixture of Monosultap and bisultap (with neutralization of hydrochloride)
1000 ml methanol was charged to a reactor. 275 gm of aqueous layer containing 1.0 M of 2,3-dichloro-N,N-dimethylallylamine hydrochloride as 70% solution obtained in step-2 was added to the reactor, followed by stirring to get a clear solution. The resultant mass was cooled to 10 °C. 53 ml of sodium hydroxide (NaOH) solution (18 N) was added to the cooled mass at 10 °C over 30 minutes, followed by stirring for 30 minutes.
501 gm of sodium thiosulfate (Na2S2O3) as pentahydrate was added to the reactor slowly over 45 minutes under stirring at room temperature, followed by stirring the reaction mass for 15 minutes. The resultant mass was heated at 70 °C for 8 hours to obtain product mass containing a mixture of monosultap and bisultap. The conversion of 2,3-dichloro-N,N-dimethylallylamine hydrochloride to the mixture of monosultap and bisultap was 98%.
Separation of monosultap and bisultap
The product mass was cooled to 50 °C to obtain a slurry, and the slurry was filtered to obtain a residue and a liquid phase. The residue was washed with two portions of 100 ml each of hot methanol (50 °C). The methanol washing was mixed with the liquid phase to obtain a combined liquid phase.
Washed residue was dried at 60°C. Analysis of the dried residue showed presence of NaCl (98%), and Na2S2O3 (2%).
The combined liquid phase was cooled to 20 ?C. The pH of cooled liquid phase was 9.0. Concentrated HCl solution was added to the cooled mixture to adjust the pH to 4.5, followed by stirring the resultant mass for 30 minutes to obtain a slurry.
The slurry was further cooled to –5°C slowly over 3 hours, followed by further stirring at –5°C for 4 hours. The resultant slurry was filtered to isolate solids as a residue comprising crude monosultap. The residue was washed with two portions of 75 ml each of cold methanol (5 °C), followed by air drying and then drying at 75 °C to obtain a first fraction comprising monosultap (yield of monosultap = 65%) Analysis of the residue showed presence of monosultap (87%), NaCl (11%), and Na2S2O3 (2%).
The filtrate obtained from the slurry was combined with the methanol washing, and the combined mixture was taken for bisultap isolation.
Bisultap Isolation
The combined mixture obtained from the slurry had a pH of 4.7. The pH of the filtrate was adjusted to 10 with NaOH lye, followed by stirring for 30 minutes. Methanol was removed from the resultant mass using 1’ packed column at 60°C under reduced pressure. The residual mass was cooled to 25 °C to obtain a second fraction comprising bisultap. The bisultap content of the second fraction was 27%. The yield of bisultap was 33%.
Thus, the total yield of monosultap and bisultap was 98%.
Step-3: Preparation of mixture of monosultap and bisultap (without neutralization of hydrochloride)
1000 ml methanol was charged to a reactor. 275 gm of aqueous layer containing 1.0 M of 2,3-dichloro-N,N-dimethylallylamine hydrochloride as 70% solution obtained in step-2 was added to the reactor, followed by stirring to get a clear solution. A first portion of Na2S2O3 (250 gm) as pentahydrate was slowly added over 30 minutes, at 25 °C, under stirring. The resultant mass was heated at refluxing temperature for 2 hours.
The reaction mass was cooled to 60°C, and a second portion of Na2S2O3 (250 gm) as pentahydrate was added to the reactor over 30 minutes while stirring at 60°C. The reaction mass was heated at 70 °C for 6 hours to obtain a product mass. Conversion by Na2S2O3 consumption as well as formation of monosultap and bisultap was 96%.
The product mass was cooled to 50 °C to obtain a slurry. Solids were separated from the slurry by filtration to obtain a residue and a liquid phase. The residue was washed with two portions of 100 ml each of hot methanol (50 °C). Methanol washing was mixed with the liquid phase to obtain a combined liquid phase.
The washed residue was dried at 60 °C. Analysis of the residue showed presence of NaCl (98%), and Na2S2O3 (2%).
The combined liquid phase was taken for monosultap isolation.
Monosultap isolation
Initial pH of the combined liquid phase was 5.0. Concentrated HCl solution was added at 25 °C to the combined liquid phase to adjust the pH to 4.5, followed by stirring the resultant mass for 30 min to obtain a slurry. The slurry was cooled to –5°C over 3 hours, followed by stirring of the cooled slurry for 4 hours at –5°C, and filtering to obtain a residue comprising monosultap and a filtrate. The residue was washed with two portions of 75 ml each of cold methanol (5 °C). The washed residue was air dried, followed by drying at 80°C to obtain a first fraction comprising monosultap. Yield of Monosultap was 56%.
Analysis of the residue showed presence of monosultap 89%, NaCl (9 %), and Na2S2O3 (2 %).
The filtrate obtained from the slurry was combined with the methanol washing, and the combined mixture was taken for bisultap isolation.
Bisultap Isolation
The combined mixture obtained from the slurry had a pH of 4.9. The pH of the filtrate was adjusted to 10 with NaOH lye, followed by stirring for 30 minutes. Methanol was removed from the resultant mass using 1’ packed column at 60°C under reduced pressure. The residual mass was cooled to 25 °C to obtain a second fraction containing bisultap. The bisultap content of the second fraction comprising bisultap content was 28%. The yield of bisultap was 37%.
Thus, the total yield of monosultap and bisultap is 93%.
Step-4: Preparation of cartap hydrochloride using the first fraction comprising monosultap
Preparation of cartap hydrochloride from monosultap is carried out in two steps, step-4A- preparation of 1,3-dithiocyanato-N,N-dimethylpropylamine from monosultap, and step-4B – preparation of cartap hydrochloride from 1,3-dithiocyanato-N,N-dimethylpropylamine.
Step-4A: 1,3-Dithiocyanato-N,N-dimethylpropylamine (dithiocyanato) preparation
450 ml water was charged to a reactor and 392 gm of the first portion comprising monosultap (as 87% purity) obtained in step-3 was added to the reactor, followed by stirring for 15 minutes. NaOH lye was added to the resultant mass followed by stirring for 1 hour to obtain a mass with a pH of 10.0.
The resultant mass was cooled to 10°C and a clear solution of NaCN (100 gm of NaCN into 200 ml of water) was added into it slowly over 3 hours at 10°C, followed by stirring for 4 hours to obtain a slurry. The slurry was filtered to obtain a residue and a filtrate. The residue was washed with MDC. The filtrate was extracted with 100 ml of MDC. The filtrate and the MDC layer obtained from extraction were mixed to obtain a combined MDC layer comprising 1,3-dithiocyanato-N,N-dimethylpropylamine in the form of a solution. Average conversion to 1,3-dithiocyanato-N,N-dimethylpropylamine was 95%.
Step-4B: Preparation of cartap hydrochloride
Combined MDC layer from Step-4A containing 1,3-dithiocyanato-N,N-dimethylpropylamine was charged to a reactor, followed by cooling to 0 °C. 200 ml of methanol was added to the reactor. 185 gm of dry HCl gas was passed through the resultant mixture over a period of 4 hours at 0 °C, followed by stirring the resultant mass for 1 hour. Temperature of the resultant mixture was raised to 30°C slowly over 2 hours, and 200 ml methanol was added to the resultant mixture. Temperature of the mass was raised to 64 °C with simultaneous distillation of MDC from the reaction mass. The resultant mass was stirred at refluxing temperature for 4 hours, followed by cooling to 0°C, and then stirring for 1 hour to obtain a slurry. The slurry was filtered to obtain a residue and a filtrate. The residue was washed with two portions of 100 ml each of cold methanol (5 °C) and dried at 80 °C under reduced pressure to obtain cartap hydrochloride (yield = 81%, and HPLC purity = 99.4%)
The filtrate and washing were combined and concentrated under reduced pressure to obtain an oily mass. Cartap hydrochloride content of the oily mass as determined by HPLC was found to be 6.5%.
Two residue and the oily mass were mixed together to obtain a first fraction of cartap hydrochloride.
Step-5: Preparation of cartap hydrochloride using the second fraction comprising bisultap
Preparation of cartap hydrochloride from monosultap is carried out in two steps, Step-5A- preparation of 1,3-dithiocyanato-N,N-dimethylpropylamine from bisultap, and Step-5B – preparation of cartap hydrochloride from 1,3-dithiocyanato-N,N-dimethylpropylamine.
Step-5A- preparation of 1,3-dithiocyanato-N,N-dimethylpropylamine from bisultap
100 ml water was charged in a reactor and 890 gm of bisultap having 40% purity obtained from step-3 was added to the reactor, followed by stirring the resultant mass for 15 minutes. The pH of the resultant mass was 10.0. The resultant mass was cooled to 10°C and a clear solution of NaCN was added to it slowly over 3 hours at 10 °C, followed by stirring the mass at same temperature for 4 hours to obtain a slurry. The slurry was filtered to obtain a residue and a filtrate. The residue was washed with MDC.
The filtrate extracted with 100 ml of MDC. Both MDC layers were mixed to obtain a combined MDC layer. Average conversion of bisultap to 1,3-dithiocyanato-N,N-dimethylpropylamine was 62%.
Step-5B: preparation of cartap hydrochloride
The combined MDC layer obtained from Step-5A containing 1,3-dithiocyanato-N,N-dimethylpropylamine was charged in a reactor and was cooled to 0°C. 200 ml of methanol was added into the reactor. 185 gm of dry HCl gas was passed slowly over a period of 4 hours at 0 °C, followed by stirring the resultant mass for 1 hour. Temperature of resultant mass was raised to 30 °C over 2 hours. 200 ml methanol was added to the reaction mass, followed by slowly raising temperature to 64 °C with simultaneous distillation of MDC from the reaction mass.
The resultant mass was stirred at refluxing temperature for 4 hours, followed by cooling to 0°C, and stirring for 1 hour to obtain a slurry. The slurry was filtered to obtain a residue and a filtrate. The residue was washed with two portions of 100 ml each of cold methanol (5 °C), and the washed residue was dried at 80°C under reduced pressure to obtain cartap hydrochloride. The yield of cartap hydrochloride was 43% with a purity of 98.7%
The filtrate and methanol washing were combined and concentrated to obtain oily mass. Cartap hydrochloride content of the oily mass as determined by HPLC was found to be 42%.
Two residue and the oily mass were mixed together to obtain a second fraction of cartap hydrochloride.
Step 6:
The first fraction of cartap hydrochloride and the second fraction of cartap hydrochloride were mixed together to obtain cartap hydrochloride. Total cartap hydrochloride obtained from monosultap (step-4) and bisultap (step-5) was 64%.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of:
? an efficient and economical process for preparation of cartap hydrochloride; and
? a process for preparing cartap hydrochloride in high yield and with high purity.
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 invention to achieve one or more of the desired objects or results. While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Variations or modifications to the formulation of this invention, within the scope of the invention, may occur to those skilled in the art upon reviewing the disclosure herein. Such variations or modifications are well within the spirit of this invention.
The numerical values given for various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the invention unless there is a statement in the specification to the contrary.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the disclosure. These and other changes in the preferred embodiment 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:1. A process for preparing cartap hydrochloride, the process comprising the following steps:
i. amination of allyl chloride with dimethylamine in the presence of at least one base to obtain N,N-dimethylallylamine;
ii. forming hydrochloride salt of N,N-dimethylallylamine using hydrogen chloride gas, followed by chlorination of N,N-dimethylallylamine hydrochloride using chlorine gas to obtain 2,3-dichloro-N-N-dimethylpropylamine hydrochloride;
iii. reacting 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with sodium thiosulfate to obtain a mixture containing monosodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (monosultap) and disodium salt of thiosulfuric acid [2-(dimethylamino)-1,3-propanediyl] ester (bisultap);
iv. separating a first fraction comprising monosultap and a second fraction comprising bisultap from the mixture;

v. cyanation of the first fraction comprising monosultap with at least one alkali metal cyanide in the presence of at least one base to obtain a first portion of dithiocyanato compound; and hydrolyzing the first portion of dithiocyanato compound with hydrogen chloride gas in the presence of at least one alcohol to obtain a first crop of cartap hydrochloride;

vi. cyanation of the second fraction comprising bisultap at least one alkali metal cyanide in the presence of at least one base to obtain a second portion of dithiocyanato intermediate; and hydrolyzing the second portion of dithiocyanato compound with hydrogen chloride gas in the presence of at least one alcohol to obtain a second crop of cartap hydrochloride; and
vii. mixing the first crop of cartap hydrochloride and the second crop of cartap hydrochloride to obtain cartap hydrochloride.
2. The process as claimed in claim 1, wherein the base is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate.
3. The process as claimed in claim 1, wherein the step-(iii) involves neutralizing 2,3-dichloro-N-N-dimethylpropylamine hydrochloride with at least one base to obtain neutralized mass followed reacting the neutralized mass with sodium thiosulfate by adding sodium thiosulfate in one portion.
4. The process as claimed in claim 1, wherein the step-(iii) involves addition of sodium thiosulfate to 2,3-dichloro-N-N-dimethylpropylamine hydrochloride in two to five portions.
5. The process as claimed in claim 1, wherein the alkali metal cyanide is at least one selected from the group consisting of sodium cyanide, and potassium cyanide.
6. The process as claimed in claim 1, wherein the alcohol is at least one selected from the group consisting of methanol, and ethanol.
7. The process as claimed in claim 1, wherein the yield of cartap hydrochloride is in the range of 55% to 75%.
8. The process as claimed in claim 1, wherein the purity of cartap hydrochloride is in the range of 95% to 99.5%.