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

“A PROCESS FOR PREPARATION OF 2,3,3,3-TETRAFLUOROPROPENE AND INTERMEDIATE THEREOF”

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

The following specification particularly describes 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 2,3,3,3-tetrafluoropropenes and their intermediates, such as pentachloropropanes.

BACKGROUND OF THE INVENTION
Hydrofluoroolefins, particularly, tetrafluoropropenes are important compounds and find applications as refrigerants, blowing agent, solvents etc. and can be prepared from intermediates, such as pentachloropropanes.
There are several methods known in the literature for the preparation of pentachloropropanes.
United States Patent No. 4535194 discloses a process for chlorination of trichloropropene to prepare pentachloropropane using chlorine in presence of an ultraviolet light or in presence of catalyst.
PCT Application 2010123148 provides a chlorination process for preparation of a 1,1,1,2,3-pentachloropropane from a mixture comprising of 1,1,3-trichloropropene (HCC-1240za) and 3,3,3-trichloropropene (HCC-1240zf). The process is carried out using an ultraviolet lamp at 0?.
The process known in the art for chlorination of trichloropropene is either using ultraviolet lamp or using a catalyst. Hence, the processes are not cost-effective, commercially feasible and generate catalyst effluent.
However, there exists a need in the art to develop a process for preparing tetrafluoropropene and its intermediates, which is economical and industrially satisfactory.

OBJECT OF THE INVENTION
The main object of present invention is to provide an economical and improved process for preparation of tetrafluoropropene and intermediates thereof, such as pentachloropropanes.

SUMMARY OF THE INVENTION
The present invention provides a process for preparation of preparation of pentachloropropane, comprising contacting trichloropropene with chlorine to produce pentachloropropane in absence of light and/or catalyst.

DETAILED DESCRIPTION OF THE INVENTION
In an embodiment, the present invention provides a process for preparation of preparation of pentachloropropane, comprising contacting trichloropropene with a chlorine to produce pentachloropropane in absence of light and/or catalyst. As used herein, “light” refers to ultraviolet light.
In an embodiment, trichloropropene refers to 3,3,3-trichloropropene (1240zf), 1,1,3-trichloropropene (1240za), or their mixture thereof. A mixture of trichloropropene refers to a mixture, comprising 3,3,3-trichloropropene and 1,1,3-trichloropropene in the range from 1-99%.
In an embodiment, trichloropropene is a mixture of 3,3,3-trichloropropene (1240zf), and 1,1,3-trichloropropene (1240za).
In an embodiment, the present invention provides a process for preparation of preparation of pentachloropropane, comprising contacting a mixture comprising trichloropropene with chlorine to produce pentachloropropane in absence of light and/or catalyst.

In an embodiment, the present invention provides a process for preparation of preparation of pentachloropropane, comprising contacting a mixture comprising trichloropropene with chlorine to produce pentachloropropane in absence of light and/or catalyst at a temperature in the range of 0-70?. The chlorination is exothermic, so temperature is maintained using an outer utility in the reactor, such as brine.
In an embodiment, the chlorine molar ratio to trichloropropene is maintained in the range of 0.8-1 and preferably 0.8.
In an embodiment, the present invention provides a process for preparation of 1,1,1,2,3-pentachloropropane (240db), comprising contacting 1,1,3-trichloropropene (1240za) with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst at 50?.
In an embodiment, the present invention provides a process for preparation of 1,1,1,2,3-pentachloropropane (240db), comprising contacting 1,1,1-trichloropropene (1240zf) with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst.
In an embodiment, the present invention provides a process for preparation of 1,1,1,2,3-pentachloropropane (240db), comprising contacting a mixture comprising trichloropropene (1240zf and 1240za) with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst.
In an embodiment, the step of contacting trichloropropene with a chlorine to produce 1,1,1,2,3-pentachloropropane (240db) is carried out in absence of ultraviolet light.
In an embodiment, the step of contacting trichloropropene with a chlorine to produce 1,1,1,2,3-pentachloropropane (240db) is carried out in absence of catalyst.
In an embodiment, the step of contacting trichloropropene with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) is carried out at a temperature in the range from 0-50? and pressure in the range from atmospheric to 12Kg/cm2.
In an embodiment, the step of contacting a trichloropropene with a chlorine is carried out in a batch or in continuous mode.
In an embodiment, trichloropropene and chlorine are continuously charged in a reactor to produce 1,1,1,2,3-pentachloropropane (240db).
The pentachloropropane is obtained by collecting the reactor outlet in a base scrubber and separating layers.
The conversion of formation of 1,1,1,2,3-pentachloropropane (240db) is greater than 70% and more preferably greater than 80%.
The selectivity of formation of 1,1,1,2,3-pentachloropropane (240db) is greater than 90% and more preferably greater than 93%.
In another embodiment, the present invention provides a process for preparation of 2,3,3,3-tetrafluoropropene, comprising the steps of:
i) contacting trichloropropene with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst;
(ii) contacting 1,1,1,2,3-pentachloropropane (240db) with HF in presence of catalyst to produce a reaction mixture comprising 2-chloro-3,3,3-trifluoropropene (1233xf);
(iii) contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF in presence of a catalyst to produce 2,3,3,3-tetrafluoropropene.
In another embodiment, the present invention provides a process for preparation of 2,3,3,3-tetrafluoropropene, comprising the steps of:
i) contacting trichloropropene with chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst;
(ii) contacting 1,1,1,2,3-pentachloropropane (240db) with HF in presence of a catalyst to produce 2,3,3,3-tetrafluoropropene.
As used herein, catalyst is selected from a group consisting of Chromia, Chromia-Alumina, Fluorinated Alumina, Fluorinated chromia, Activated carbon, or like. The catalyst has been fluorinated using HF.
In another embodiment of the present invention, the catalyst is activated using hydrogen fluoride, in-situ to form active catalyst.
In preferred embodiment, the reaction of catalyst and hydrogen fluoride gives active catalyst, wherein it is used in-situ. As used herein, “active catalyst” refers to a catalyst formed by reaction of catalyst and hydrogen fluoride.
In preferred embodiment, active catalyst for present invention is chromium oxyfluoride. It is observed that chromium oxyfluoride catalyst is not stable at room temperature.
In preferred embodiment, the chromia catalyst is activated in a reactor before fluorination and dehydrohalogenation. The chromia catalyst used for present invention has surface area from 90-150m2/g and pore volume of greater than 0.2cc/g.
In preferred embodiment, chromia catalyst is amorphous in nature and used in the pellet form.
In an embodiment, catalyst is dehydrated before activation of catalyst using HF.
In preferred embodiment, after dehydration, chromia catalyst is fluorinated using hydrogen fluoride or a mixture of nitrogen and hydrogen fluoride to form chromium oxyfluoride in-situ, which is the active catalyst for present invention. The concentration of hydrogen fluoride may vary from 1-100 % and more preferably 50-90 % in a mixture of nitrogen and hydrogen fluoride.
In an embodiment, catalyst used for present invention is supported on carbon. The chromia catalyst is present as a fixed bed catalyst.
In an embodiment, the step of contacting 1,1,1,2,3-pentachloropropane (240db) with HF is carried out to produce a reaction mixture comprising 2-chloro-3,3,3-trifluoropropene (1233xf). The molar ratio hydrogen fluoride (HF) to 1,1,1,2,3-pentachloropropane (240db) is in the range from 2-20 equivalents.
In an embodiment of the present invention, the step of contacting 1,1,1,2,3-pentachloropropane (240db) with HF is carried out at 320-370?.
In an embodiment of the present invention, the step of contacting 1,1,1,2,3-pentachloropropane (240db) with HF is carried out using a catalyst selected from a group consisting of Chromia, Chromia-Alumina, Fluorinated Alumina, Fluorinated chromia, Activated carbon, or like.
In another embodiment of the present invention, the step of contacting 1,1,1,2,3-pentachloropropane (240db) with HF using a catalyst to produce 2-chloro-3,3,3-trifluoropropene (1233xf) is carried out at a temperature range of 200-370?.
In another embodiment of the present invention, the step of contacting 1,1,1,2,3-pentachloropropane (240db) with HF using a catalyst produces 2-chloro-3,3,3-trifluoropropene (1233xf) along with unreacted 2,3-dichloro-1,1,1-trifluoropropane (243db), 1,1,2,3,3-Pentafluoropropane (245ea), 1,1,3-trichloro-3,3-difluoropropane (242db), 1,1,2,3-tetrachloropropene (1230xa), and unreacted 1,1,1,2,3-pentachloropropane (240db), hydrochloric acid and HF. These compounds can be easily separated by using physical separation techniques.
In an embodiment, the present invention provides a process for preparation of 2,3,3,3-tetrafluoropropene, comprising the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF in presence of a catalyst to produce 2,3,3,3-tetrafluoropropene.
In another embodiment, the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF is carried out at a temperature of 200-370?.
In another embodiment, the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF is carried out in presence of a catalyst selected from a group consisting of Chromia, Chromia-Alumina, Fluorinated Alumina, Fluorinated chromia, Activated carbon, or like.
In another embodiment, the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF is carried out in presence of a catalyst selected from a group consisting of Chromia, Chromia-Alumina, wherein the catalyst has been fluorinated using HF.
In another embodiment of the present invention, the catalyst is activated using HF prior to its contact with 2-chloro-3,3,3-trifluoropropene (1233xf).
In an embodiment of the present invention, the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF comprises fluorination and dehydrohalogenation.
In an embodiment, the step of contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF, wherein the molar ratio hydrogen fluoride (HF) to 2-chloro-3,3,3-trifluoropropene (1233xf) is in the range from 2-20 equivalents.
In specific embodiment, activation, and simultaneous fluorination and dehydrohalogenation is carried out in an Inconel reactor.
In an embodiment, fluorination and dehydrohalogenation is carried out in presence of active catalyst.
In an embodiment, chromium oxyfluoride is prepared in-situ for preparation of tetrafluoropropene.
In an embodiment present invention, the residence time for step of contacting 2-chloro-3,3,3-trifluoropropene with hydrogen fluoride in reactor is 5-60 seconds.
In an embodiment, the catalyst is dehydrated before activation of catalyst using hydrogen fluoride.
The selectivity of formation of 2,3,3,3-tetrafluoropropene is greater than 75% and more preferably greater than 85% and most preferably between 85-95%.
In an embodiment, reactor outlet stream after fluorination and dehydrohalogenation is quenched in a base solution or an aqueous scrubber. The base for present invention is selected from a group consisting of sodium carbonate, potassium carbonate, potassium hydroxide, sodium hydroxide or like. For present invention, quenching refers to neutralising acid content from a stream. The acid content may be due to presence of hydrogen fluoride, hydrogen chloride or mixture thereof.
In an embodiment, reaction outlet stream is quenched and distilled to obtain tetrafluoropropene.
In an embodiment, 2,3,3,3-tetrafluoropropene is isolated by distillation. The catalyst and excess hydrogen fluoride is regenerated and recycled.
Tetrafluoropropene is isolated by any method known in the art, for example, chemical separation, extraction, acid-base neutralization, distillation, evaporation, and filtration or a mixture thereof.
In another embodiment, the present invention provides a process for preparation of 2,3,3,3-tetrafluoropropene, comprising the steps of:
i) reacting tetrachloromethane and ethylene to obtain 1,1,1,3-tetrachloropropane;
ii) reacting 1,1,1,3-tetrachloropropane using a base to obtain a mixture comprising trichloropropene;
iii) contacting mixture of trichloropropene with a chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst;
(iv) contacting 1,1,1,2,3-pentachloropropane (240db) with HF in presence of catalyst to produce a reaction mixture comprising 2-chloro-3,3,3-trifluoropropene (1233xf);
(v) contacting 2-chloro-3,3,3-trifluoropropene (1233xf) with HF in presence of a catalyst to produce 2,3,3,3-tetrafluoropropene.
In another embodiment, the present invention provides a process for preparation of 2,3,3,3-tetrafluoropropene, comprising the steps of:
i) reacting tetrachloromethane and ethylene to obtain 1,1,1,3-tetrachloropropane;
ii) reacting 1,1,1,3-tetrachloropropane using a base to obtain a mixture comprising trichloropropene;
iii) contacting mixture of trichloropropene with a chlorine to produce 1,1,1,2,3-pentachloropropane (240db) in absence of light and/or catalyst;
(iv) contacting 1,1,1,2,3-pentachloropropane (240db) with HF in presence of catalyst to produce 2,3,3,3-tetrafluoropropene.
The raw materials can be commercially procured or prepared by any method known in the art.
The raw material trichloropropene used in the chlorination process may be prepared by using the process disclosed in EP0131560B1.
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 1,1,1,3-tetrachloropropane (250fb)
In a 5L autoclave, carbon tetrachloride (5500 g), triethyl phosphate (81.5 g), Fe Powder (11 g) and iron chloride (21 g) were charged. The reaction mass was heated to 120? and started adding ethylene (900 g). The ethylene addition was continued for 7 hours, and the reactor pressure was maintained at 10 kg/cm2. After reaction, the reaction mass was analysed and sent to a series of distillation column where unreacted carbon tetrachloride was removed and recycled. The next column operated under vacuum, wherein pure R-250fb was removed as top cut. The bottom mass of the second distillation containing some pentachloropropane and catalyst which was again recycled back into reactor.
Purity: 99 %; Yield: 95 %.
Example 2: Preparation of a mixture of 3,3,3-trichloropropene and 1,1,3-trichloropropene.
1,1,1,3-tetrachloropropane (R-250fb) (3 kg) and trioctylmethylammonium chloride (12 g) were charged in a reactor. The reaction mixture was heated to 60? and added an aqueous solution of sodium hydroxide (15%, 4.0 kg) in 3 hours with flow of 1.3 kg/hr. The reaction mixture was separated into two layers and bottom organic layer (2.5 kg) was separated from aqueous layer. The organic layer obtained had composition as given below.
Composition %: Unreacted R-250fb: 20%; 1,1,3-Trichloropropene: 33%; 3,3,3-Trichloropropene (1240zf): 44 %.
The organic layer was distilled to obtain a mixture of 1,1,3-Trichloropropene and 3,3,3-Trichloropropene (Purity: 97%).
Example 3: Preparation of 1,1,1,2,3-pentachloropropane (240db)
A mixture of trichloropropene (1,1,3-trichloropropene and 3,3,3-trichloropropene, 97%) with flow of 475 g/hour was fed along with chlorine with 187 g/hour in a Jacketed Inconel tubular reactor and maintained at 50 ? and obtained 1,1,1,2,3-pentachloropropane (240db) in below composition. Conversion: 70%, Selectivity: 93.7%
Example 4: Preparation of 2-chloro-3,3,3-trifluoropropene
In an Inconel reactor, Chromia catalyst was filled and heated to 300°C in the presence of nitrogen to drive out bound and unbound moisture. The nitrogen gas was passed through the reactor at 300°C for 10-15 hours. Then at this temperature, hydrogen fluoride along with nitrogen was passed to activate the chromia catalyst. During activation, Reactor temperature was raised up to 375°C. After the activation, the reactor temperature was slowly decreased to 330°C. Anhydrous HF flow was then adjusted to 172 g/hour, after the flow rate was achieved, 1,1,1,2,3 pentachloropropane feed was started with flow of 124 g/hour. The reactor outlet was purged in water scrubber and collected in a condenser. The reactor outlet composition was given below.
Example 5: Preparation of 2,3,3,3-tetrafluoropropene
In an Inconel reactor, Chromia catalyst was filled and heated to 300°C in the presence of nitrogen to drive out bound and unbound moisture. The nitrogen gas was passed through the reactor at 300°C for 10-15 hrs. Then at this temperature, hydrogen fluoride along with nitrogen was passed to activate the chromia catalyst. During activation, Reactor temperature is raised up to 375 ?. After the activation, the reactor temperature is slowly decreased to 350?. Anhydrous HF flow was then adjusted to 227g/h, and 2-chloro-3,3,3-trifluoropropene feed was fed with 145 g/hour. The pre-vaporised hydrogen fluoride and 2-chloro-3,3,3-trifluoropropene were mixed and passed through active catalyst bed at 350°C in the reactor. The reactor outlet was purged in water scrubber and collected in a condenser.
,CLAIMS:WE CLAIM
1. A process for preparation of 1,1,1,2,3-pentachloropropane, comprising contacting trichloropropene with chlorine to produce pentachloropropane in absence of light and/or catalyst.
2. The process as claimed in claim 1, wherein the reaction of trichloropropene with chlorine to produce 1,1,1,2,3-pentachloropropane in absence of light and/or catalyst is carried out at a temperature in the range of 0-70?.
3. The process as claimed in claim 1, wherein trichloropropene is a mixture of 3,3,3-trichloropropene (1240zf), and 1,1,3-trichloropropene (1240za).
4. The process as claimed in claim 1, wherein the chlorine molar ratio to trichloropropene is maintained in the range of 0.8-1.

Dated this 01st day of March 2024.