PROCESS FOR THE PREPARATION OF 1,1,2,3-TETRACHLOROPROPENE
Field of the invention
The present invention provides a process for the preparation of a compound of Formula I. More particularly, the present invention provides a process for the preparation of 1,1,2,3-tetrachloropropene.
Background of the invention
The chlorinated propenes, particularly, 1,1,2,3-tetrachloropropene is an important precursor for the production of 2,3,3,3-tetrafluoropropene (HFO-1234yf). The fluorinated olefins are known to be effective refrigerants, fire extinguishants, heat transfer media, propellants, foaming agents, blowing agents, gaseous dielectrics, sterilant carriers, polymerization media, particulate removal fluids, carrier fluids, buffing abrasive agents, displacement drying agents and power cycle working fluids. Along with their innumerable applications, they have added advantage of posing no threat to the ozone layer as being devoid of chlorine atom.
U.S. Patent No.3,446,859 discloses a process for the production of chlorinated allyl halides by reacting in a vapour phase a chlorinated olefin with a methyl halide at a temperature in the range of 400oC to 700oC. This patent also mentions about free radical initiators like oxygen, chlorine, chlorine yielding chlorocarbons and like.
U.S. Patent No.8,258,353 provides a process for the production of chlorinated and/or fluorinated propenes by reacting, at elevated pressures i) a chloroethylene or a chlorofluoroethylene and ii) a methane, chloromethane, fluoromethane or chlorofluoromethane, to provide at least one chlorinated and/or fluorinated propene. The reaction preferably takes place in the presence of initiators such as carbon tetrachloride, chlorine, hexachloroethane, benzotrichloride, hexachloroacetone or a combination of these. 2
The present invention relates to a process for the free radical reaction between 1,1,2,2-tetrachloroethene and methylchloride in the presence of certain compounds which act as free radical initiator. In this case the compound is trichloroacetylchloride (TCAC).
The present invention provides a process which is simple, economically viable and industrially doable.
Summary of the invention
The present invention provides a process for the preparation of a compound of Formula I
CYCl=CCl-CH2X,
comprising reacting a chlorinated olefin of Formula II
CYCl=CCl2
with a methyl halide of Formula III
CH3-X,
wherein Y is selected from chlorine and hydrogen and X is selected from chlorine, fluorine and bromine, and
wherein said reaction takes place in a vapour phase and in the presence of trichloroacetylchloride.
The present invention also provides a process of preparing 1,1,2,3-tetrachloropropene comprising reacting methyl chloride with 1,1,2,2-tetrachloroethene, wherein the said reaction takes place in a vapour phase and in the presence of trichloroacetylchloride.
The inventors have observed that upon maintaining the conversion of 1,1,2,2-tetrachloroethene at around 7-9%, the selectivity of 1,1,2,3-tetrachloropropene so obtained is greater than 85 %. Further, the carbon lay down decreases thus increasing the cycle life of the reaction.
Detailed description of the invention
The present invention provides a process for the preparation of a compound of Formula I
CYCl=CCl-CH2X,
comprising reacting a chlorinated olefin of Formula II 3
CYCl=CCl2
with a methyl halide of Formula III
CH3-X,
wherein Y is selected from chlorine and hydrogen and X is selected from chlorine, fluorine and bromine, and
wherein said reaction takes place in a vapour phase and in the presence of trichloroacetylchloride.
The present invention also provides a process of preparing 1,1,2,3-tetrachloropropene comprising reacting methyl chloride with 1,1,2,2-tetrachloroethene, wherein the said reaction takes place in a vapour phase and in the presence of trichloroacetylchloride.
The 1,1,2,2-tetrachloroethene may be obtained commercially or can be prepared by any of the methods known in the art.
The process of the present invention may be carried out at a temperature in the range of from about 460oC to 560oC.
The 1,1,2,3-tetrachloropropene prepared by virtue of the process of present invention has a selectivity greater than 80.0% by Gas chromatography.
The term ‘about’ refers to a variation of 10% on the higher and lower side of specified parameter.
While the present invention has been described in terms of its specific embodiments, certain modifications and equivalents will be apparent to those skilled in the art and are intended to be included within the scope of the present invention.
The following examples are given by way of illustration and therefore should not be construed to limit the scope of the present invention.
Examples
Example 1: Preparation of 1,1,2,3-tetrachloropropene 4
Methyl chloride (@ a feed rate of 341 g/hr) and 1,1,2,2-tetrachloroethene containing 3000 ppm of trichloroacetylchloride (@ a feed rate of 279 g/hr) was preheated to 1800C in a double pipe heat exchanger using high pressure steam and then vaporized in a 1” 500 mm length electrical superheater where the temperature was brought to the reaction temperature, and then fed to a 1” Inconel hollow reactor of 750 mm length which was maintained at 4600C by electrical heaters and a pressure of 10 kg/cm2g. The molar ratio of methyl chloride: 1,1,2,2-tetrachloroethene was maintained at 4:1. The product stream was collected in a collection pot which was also maintained at 10kg/cm2g. The excess pressure which is mainly due to the byproduct HCl was vented out to water scrubber. The sample from collection pot was analysed by gas chromatography after venting methyl chloride.
Analysis:
1,1,2,2-tetrachloroethene conversion: 7-9 %
Selectivity of 1,1,2,3-tetrachloropropene: 87 %.

We claim:
1. A process for the preparation of a compound of Formula I
CYCl=CCl-CH2X,
comprising reacting a chlorinated olefin of Formula II
CYCl=CCl2
with a methyl halide of Formula III
CH3-X,
wherein Y is selected from chlorine and hydrogen and X is selected from chlorine, fluorine