The present invention provides a process for the preparation of a compound of
Formula I.
F3C O CF2CF3
F3C F
Formula I
Background of the invention
The compound of Formula I is useful as an intermediate for preparing compounds, such as, perfluoroethylisopropylketone, which has numerous applications. Particularly, perfluoroethyl isopropylketone is used as fire extinguishing agent apart from being used as a cleaning agent and a solvent.
The Chinese Patent Application No. 103787854 describes a process of preparation of perfluoro-2,3-epoxy-2-methyl pentane by reacting perfluoro-2-methyl-2-pentene with sodium hypochlorite in the presence of polar aprotic solvent. The inventors of the present invention have observed that carrying out the reaction in the absence of phase transfer catalyst,leads to incomplete reaction and separation of reactant and product becomes difficult due to very close boiling points (boiling point of perfluoro-2-methyl-2-pentene is 55°C and perfluoro-2-methyl-2,3-epoxypentane is 53°C).Additionally, far longer time is required for reaction completion.
The Chinese Patent Application No. 102992986 describes a process for the preparation of perfluoro ethyl isopropylketone and its intermediate, perfluoro-2,3-epoxy-2-methyl pentane. The epoxidation reaction is carried out by treating perfluoro-2-methyl-2-pentene with an oxidant in the presence of a phase transfer

catalyst, a solvent and an additional catalyst. The additional catalyst provided in the prior art istitanium silicate, phosphotungstic acid, KF / AI2O3, CsF / AI2O3, transition metal porphyrin complex compounds, Schiff s base complexes, Mg-La composite oxide, one-component metal oxide, supported alkali metal or hydroxide. The described process suffers from the drawback that the use of additional catalyst results in effluent formationand hence making it difficult to manage at industrial scale. Also, use of additional catalyst adds on to the cost thereby making the process industrially unfavourable.
While working on the present invention, the inventors have observed that, carrying out the reaction using phase transfer catalyst, without additional catalyst, overcomes the disadvantages associated with the prior arts. Thus, present invention provides a simple, economical and industrially feasible process.
Summary of the invention
The present invention provides a process for the preparation of a compound of
Formula I, comprising:
a) contacting a compound of Formula II with an oxidant in the presence of a phase transfer catalyst to obtain the compound of Formula I; and
b) isolating the compound of Formula I obtained from step a),
F3C CF2CF3 F3C O CF2CF3
F3C F F3C F
Formula II Formula I
wherein the step a) is carried out in absence of an additional catalyst.
Detailed description of the invention
The present invention provides a process for the preparation of a compound of
Formula I, comprising:

a) contacting a compound of Formula II with an oxidant in the presence of a phase transfer catalyst to obtain the compound of Formula I; and
b) isolating the compound of Formula I obtained from step a),
F3C CF2CF3 F3C O CF2CF3
F3C F F3C F
Formula II Formula I
wherein the step a) is carried out in absence of an additional catalyst.
The compound of Formula II may be obtained commercially or may be prepared by any method known in the art, for example, as disclosed in EP Patent No. 2862850.
The step a) is carried out in the presence of oxidant selected from the group consisting of sodium hypochlorite, calcium hypochlorite, hydrogen peroxide, peraceticacid and N- Oxides.
The preferred N-oxides are selected from the group consisting of pyridineN-oxides, substituted pyridine N-oxides, n-alkyl morpholine N-oxides, trialkylamine N-oxides, quinoline N-oxides, substituted quinolone N-oxides, isoquinoline N-oxides, substituted isoquinoline N-oxides, pyrazine N-oxides, substituted pyrazine N-oxides, pyrimidineN-oxides, substituted pyrimidine N-oxides, pyridazine N-oxides, substituted pyridazine N-oxides, quinoxalineN-oxides and substituted quinoxaline N-oxides.
The phase transfer catalyst used in the step a) is selected from the group consisting of trioctyl methyl ammonium chloride, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, methyltricaprylammonium chloride, methyltributylammonium chloride, crown ethers and urea or a mixture thereof.

The step a) take place in the presence or absence of a solvent. The solvent used can be acetonitrile. The step a) may take place at a temperature in the range of -5°C to 25°C for 0.5 to 12 hours.
An "additional catalyst" is a catalyst other than phase transfer catalyst. Additional catalyst may be acidic or basic catalyst.
The compound of Formula I as prepared by the process of present invention may be used to prepare perfluoro-2-methyl pentanone by any method known in the art.
The compound of Formula I is isolated by any of the methods known in the art, for example, distillation, evaporation and layer separation or mixture thereof.
In a preferred embodiment, 0.56 moles of acetonitrile is used as a solvent, 10% aqueous sodium hypochlorite solution is used as an oxidant and 0.01 moles of trioctyl methyl ammonium chloride is used as a phase transfer catalyst, all are charged in a round bottom flask fitted with condenser and stirrer. The 0.17 moles of l,l,l,3,4,4,5,5,5-nonafluoro-2-(trifluoromethyl)pent-2-ene is then added to the round bottom flask in a lot-wise manner at 0°C and the temperature of the mixture is maintained in the range of 0°C to 5°C. After 3.5 hours of stirring, organic layer is separated to obtain the title compound.
The compound of Formula I as obtained by the process of the present invention has a purity greater than 95% by gas chromatography.
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
Preparation of 2-fluoro-2-(pentafluoroethyl)-3,3-bis(trifluoromethyl)oxirane Acetonitrile (23 g, 0.56 mol), aqueous sodium hypochlorite (350g, 10%) and trioctyl methyl ammonium chloride (0.76 g, 0.01 mol) were taken in 500 mL round bottom flask fitted with condenser and stirrer. The 1,1,1,3,4,4,5,5,5-nonafluoro-2-(trifluoromethyl)pent-2-ene (50 g, 0.17 mol) was added portion-wise to the reaction mixture at 0°C and the temperature of the mixture was maintained in the range of 0°C to 5°C. After 3.5 hours of stirring, organic layer was separated to obtain the title compound. Yield(%) = 74 Purity (%) = 96

WE CLAIM:

1.A process for the preparation of a compound of Formula I, comprising:
a) contacting a compound of Formula II with an oxidant in the presence of a phase transfer catalyst to obtain the compound of Formula I; and
b) isolating the compound of Formula I obtained from step a),
F3C CF2CF3 F3C O CF2CF3
F3C F F3C F
Formula II Formula I
wherein the step a) is carried out in absence of an additional catalyst.
2. The process as claimed in claim 1, wherein the additional catalyst is a catalyst other than phase transfer catalyst.
3. The process as claimed in claim 1, wherein the step a) is carried out in presence of oxidant selected from the group consisting of sodium hypochlorite, calcium hypochlorite, hydrogen peroxide, peraceticacid and N- Oxides.
4. The process as claimed in claim 3, wherein the N-oxides are selected from the group consisting of pyridine N-oxides, substituted pyridine N-oxides, n-alkyl morpholine N-oxides, trialkylamine N-oxides, quinoline N-oxides, substituted quinolone N-oxides, isoquinoline N-oxides, substituted isoquinoline N-oxides, pyrazine N-oxides, substituted pyrazine N-oxides, pyrimidineN-oxides, substituted pyrimidine N-oxides, pyridazine N-oxides, substituted pyridazine N-oxides, quinoxalineN-oxides and substituted quinoxaline N-oxides.
5. The process as claimed in claim 1, wherein the step a) is carried out in presence of phase transfer catalyst selected from the group consisting of trioctylmethyl ammonium chloride, benzyltrimethylammonium chloride,

benzyltriethylammonium chloride, methyltricaprylammonium chloride, methyltributyl ammonium chloride, crown ethers and urea or a mixture thereof.
6. The process as claimed in claim 1, wherein the step a) is carried out in presence of acetonitrile.
7. The process as claimed in claim 1, wherein the step a) is carried out at a temperature in the range of-5°C to 25°C for 0.5 hours to 12 hours.