DESC:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
THE PATENT RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

“A PROCESS FOR PREPARATION OF 1-(CHLOROACETYL)-2-(TRIFLUOROACETYL)HYDRAZINE”

SRF LIMITED, AN INDIAN COMPANY,
SECTOR 45, BLOCK-C, UNICREST BUILDING,
GURGAON – 122003,
HARYANA (INDIA)

The following specification particular describe the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention provides a process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine.

BACKGROUND OF INVENTION
The 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine mainly used as intermediate for complex organic molecules in the pharmaceutical or agricultural industries.
The various processes are known for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine.
United States Patent No. 8,969,558 discloses a process for preparation of N'-(2-chloroacetyl)-trifluoroacetohydrazine from hydrazine hydrate, ethyl trifluoroacetate and chloroacetyl chloride in acetonitrile. The process involves multiple operations for isolation of the product using a combination of water and ethylacetate.
Chinese Patent No. 103483218 discloses a process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine from hydrazine hydrate and ethyl trifluoroacetate using large quantity of methyl tert-butyl ether.
PCT Application No. 2005003135 discloses a process for preparation of N'-(2-chloroacetyl)-trifluoroacetohydrazine from hydrazine hydrate, ethyl trifluoroacetate and chloroacetyl chloride in acetonitrile solvent.
The known processes either involve multiple operations for product isolation or uses large quantity of solvent hence not viable for industrial production and there is a need to develop a process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine that is economical, selective, and uses less operation for isolation of product with high yield and purity.
The present invention involves simple operation of adding water at reaction termination stage for complete removal of hydrazine hydrate, followed by addition of a drying agent.

OBJECT OF INVENTION
The present invention provides a process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine which is economical, selective, and uses less operation for isolation of product with high yield and purity.

SUMMARY OF INVENTION
In an aspect, the present invention provides a process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine, comprising the steps of:
a) reacting ethyl trifluoroacetate and hydrazine hydrate to form a reaction mixture in an organic solvent;
b) adding chloroacetyl chloride and 50% aqueous base in the reaction mixture;
c) adding water to the reaction mixture and separating the layers;
d) adding a drying agent in the organic layer and distilling a quantity of organic layer to obtain a slurry;
e) filtering the slurry and isolating the 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine.

DETAILED DESCRIPTION OF INVENTION
The organic solvent may be selected from methyl tert-butyl ether, 2-methyl tetrahydrofuran, tetrahydrofuran, diethyl ether and isopropyl ether or more mixtures.
In a preferred embodiment, the preparation of 1-(chloroacetyl)-2- (trifluoroacetyl)hydrazine is carried out in methyl tert-butyl ether.
In an embodiment, the molar ratio of ethyl trifluoroacetate: hydrazine hydrate: chloroacetyl chloride is 1: 1.0-1.5: 1.0-1.2.
In an embodiment, the molar ratio of ethyl trifluoroacetate: hydrazine hydrate: chloroacetyl chloride is 1: 1:1.
In an embodiment, the weight ratio of solvent to hydrazine hydrate is selected in the range from 2-4 and more preferably between 2.5-3.
As used herein, ‘drying agent’ may be selected from toluene, xylene and o-xylene or the like.
The preferred drying agent for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine is toluene.
The volume ratio of drying agent to organic solvent is selected in the range from 1-3.
In an embodiment, the drying agent is recycled and reused in further batches.
The quantity of water added in the reaction mass is 1-3/10 of organic solvent.
In an embodiment, a quantity of organic fraction is removed from organic layer via distillation.
In an embodiment 50% to 70% of organic layer is removed during distillation step. In another embodiment, half quantity of organic layer is removed at distillation step. In another embodiment the two by third quantity of organic is removed via distillation. It will save long reaction time for complete removal of solvent.
In an embodiment, the slurry obtained after distillation contains water content less than 5000 ppm, preferably 5-4000ppm of water.
In an embodiment, water is added at reaction termination and organic and aqueous layers are separated. The organic layer is added with toluene and distilled half volume of organic layer.
The present invention provides a process for preparation of 1-(chloroacetyl) -2- (trifluoroacetyl) hydrazine, comprising the steps of:
a) reacting ethyl trifluoroacetate and hydrazine hydrate to form a reaction mixture in a methyl tert-butyl ether;
b) adding chloroacetyl chloride and 50% sodium hydroxide aqueous solution in the reaction mixture;
c) adding water to the reaction mixture and separating the layers;
d) adding toluene to the organic layer and distilling it to obtain a slurry;
e) filtering the slurry and isolating the 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine.
In an embodiment, 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine obtained in the present invention is used for the preparation of 2-(chloromethyl)-5-(trifluoromethyl)-1,3,4-oxadiazole.
In an embodiment, 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine obtained in the present invention is used for the preparation of 2,2,2-trifluoro-N-(piperazin-2-ylidene) acetohydrazide.
In an embodiment, 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine obtained in the present invention is used for the preparation of 3-(trifluoro)-5,6,7,8-tetrahydro-[1,2,4]triazolo[4,3-a]pyrazine hydrochloride.
Unless stated to the contrary, any of the words “comprising”, “comprises” and includes mean “including without limitation” and shall not be construed to limit any general statement that it follows to the specific or similar items or matters immediately following it.
Embodiments of the invention are not mutually exclusive but may be implemented in various combinations. The described embodiments of the invention and the disclosed examples are given for the purpose of illustration rather than limitation of the invention as set forth in the appended claims.
The following example is given by way of illustration and therefore should not be construed to limit the scope of the present invention.

EXAMPLES
Example 1: Preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine.
Methyl tert-butyl ether (700 ml) and hydrazine hydrate (123 gm) were added to a reactor at 25-30°C. The reaction mass was cooled to 5-10°C and a solution of ethyl trifluoroacetate (350 gm in 350 ml of methyl tert-butyl ether) was added dropwise to the reaction mass in 1-2 hours at 5-15°C. After addition, temperature was raised gradually to 20-22°C and stirred for an hour. After completion of the reaction, the reaction mass was cooled to 0-5°C. Chloroacetyl chloride (306 gm) and 50% sodium hydroxide solution (221 gm) were added simultaneously into the reaction mass at 0-10°C in 2-3 hours. After addition, temperature was raised gradually to 20-22°C and reaction mass was stirred for an hour. Water (70 gm) was added into the reaction mass and stirred for 30 minutes. The layers were separated. Toluene (700*2 ml) was added in the organic layer and distilled half volume at 20-30°C under reduced pressure (300-50 mbar) for achieving the water content <0.5% of slurry. Then, slurry was filtered and washed the wet cake with toluene to obtain 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine.
Purity (GC): 98%
Yield: 92 % ,CLAIMS:WE CLAIM
1. A process for preparation of 1-(chloroacetyl)-2-(trifluoroacetyl)hydrazine, comprising the steps of:
a) reacting ethyl trifluoroacetate and hydrazine hydrate to form a reaction mixture in an organic solvent;
b) adding chloroacetyl chloride and 50% aqueous base in the reaction mixture;
c) adding water to the reaction mixture and separating the layers;
d) adding a drying agent in the organic layer and distilling a quantity of organic layer to obtain a slurry; and
e) filtering the slurry and isolating the 1-(chloroacetyl)-2-(trifluoroacetyl) hydrazine.
2. The process as claimed in claim 1, wherein the organic solvent is selected from a group consisting of methyl tert-butyl ether, 2-methyl tetrahydrofuran, tetrahydrofuran, diethyl ether and isopropyl ether or a mixture thereof.
3. The process as claimed in claim 1, wherein the molar ratio of ethyl trifluoroacetate: hydrazine hydrate: chloroacetyl chloride is 1: 1.0-1.5: 1.0-1.2.
4. The process as claimed in claim 1, wherein the weight ratio of solvent to hydrazine hydrate is selected in the range from 2-4.
5. The process as claimed in claim 1, wherein the drying agent is selected from a group consisting of toluene, xylene and o-xylene.
6. The process as claimed in claim 1, wherein the volume ratio of drying agent to organic solvent is selected in the range from 1-3.
7. The process as claimed in claim 1, wherein 50% to 70% of organic layer is removed during distillation step.
8. The process as claimed in claim 1, wherein the slurry obtained after distillation contains water content less than 5000 ppm.
9. The process as claimed in claim 1, wherein the drying agent is recycled and reused.
10. The process as claimed in claim 1, wherein the ratio of quantity of water added in the reaction mass is 1-3/10 of organic solvent.

Dated this 02nd day of September 2022.