DESC:PROCESS FOR THE PREPARATION OF ALKYL HALO-SUBSTITUTED PROPANOATE

Field of the invention

The present invention provides a process for the preparation of methyl 2,3-dibromo-2-chloropropanoate of Formula I.

Background of the invention

The methyl 2,3-dibromo-2-chloropropanoate is useful as a starting material for the preparation of methyl fluoro acrylate, which is a key intermediate for agrochemicals and pharmaceuticals.

Formula I

The present invention provides a process of preparation of methyl 2,3-dibromo-2-chloropropanoate of Formula I 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 having purity greater than 97%, comprising;
a) reacting a compound of Formula II with bromine to obtain the compound of Formula I having purity greater than 97%; and
b) isolating the compound of Formula I having purity greater than 97% from step a).

Formula I

Formula II

In an aspect, the present invention provides a process of preparation of a compound of Formula II, comprising:
a) reacting a compound of Formula III with an organic base in the presence of water to obtain the compound of Formula II,
b) Isolating the compound of Formula II from step b).

Formula III

In another aspect the present invention provides a process of preparation of a compound of Formula I, comprising:
a) reacting a compound of Formula III with an organic base to obtain a compound of Formula II,
b) optionally, isolating the compound of Formula II from step a),
c) contacting bromine with step a) or b) to obtain a compound of Formula I, and
d) isolating the compound of Formula I from step c)

Detailed description of the invention

The present invention provides a process for the preparation of a compound of Formula I having purity greater than 97%, comprising;
a) reacting a compound of Formula II with bromine to obtain the compound of Formula I having purity greater than 97%; and
b) isolating the compound of Formula I having purity greater than 97% from step a).

Formula I

Formula II

The compound of Formula II was reacted with bromine at a temperature in the range of 10oC to 58oC.

In an aspect, the present invention provides a process of preparation of a compound of Formula II, comprising:
a) reacting a compound of Formula III with an organic base in the presence of water to obtain the compound of Formula II,
b) isolating the compound of Formula II from step b).

Formula III

The step a) is carried out at a temperature in the range of 20oC to 60oC.
The step a) may be carried out in the presence of polymerization inhibitors such as 2,6-Bis(1,1-dimethylethyl)-4-methylphenol (BHT), methyl hydroquinone, hydroquinone, phenothiazine or other polymerization inhibitors known in the art.

In another aspect the present invention provides a process of preparation of a compound of Formula I, comprising:
a) reacting a compound of Formula III with an organic base to obtain a compound of Formula II,
b) optionally, isolating the compound of Formula II from step a),
c) contacting bromine with step a) or b) to obtain a compound of Formula I, and
d) isolating the compound of Formula I form step c)

The step a) is carried out at a temperature in the range of 20oC to 60oC and the step c) is carried out at a temperature in the range of 10oC to 58oC.

The step a) may be carried out in the presence of polymerization inhibitors such as 2,6-Bis(1,1-dimethylethyl)-4-methylphenol (BHT), methyl hydroquinone, hydroquinone, phenothiazine or other polymerization inhibitors known in the art.

The bromine may be in gaseous form or liquid form. The bromine utilized in present invention is greater than 90% pure.
The step a) is carried out in the presence of organic base, for example, triethyl amine, diethyl amine and other organic base as known in the art.

The compound of Formula III may be obtained commercially or can be prepared by any of the methods known in the art, for example, as in DE Patent No. 2,352,153.
The isolation of the compound of Formula I is carried out by distillation, evaporation, and layer separation or mixture thereof.

The compound of Formula I, obtained by the process of the present invention has a purity greater than 97% by gas chromatography.

The compound of Formula I, as prepared by the process of the present invention, is used to prepare methyl 2-fluoroacrylate by any method known in the art.

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 Methyl-2,3-dibromo-2-chloropropanoate
a) Methyl-2,3-dichloropropionate (200g, 1.27mol), water (174g) and BHT (1.12 g, 0.005 mol) were taken into a reaction vessel fitted with a mechanical stirrer. Triethylamine (128.3 g, 1.27mol) was added drop wise to methyl-2,3-dichloropropionate for 0.50 hours and the progress of the reaction was monitored by gas chromatography. After the completion of reaction, the organic layer was separated from the aqueous layer and the organic layer contained the crude methyl 2-chloroprop-2-enoate.

b) The step a) product (496 g, 4.13 mol) was taken into the reaction vessel with mechanical stirrer, Bromine (670 g, 4.18 mol) was added drop-wise to the reaction vessel, the temperature was maintained below 40°C. Progress of the reaction was monitored by gas chromatography. The reaction mass was purified by distillation at 86°C and 8mm of mercury pressure to give Methyl-2,3-dibromo-2-chloropropanoate as a pale yellow liquid.
Yield (%): 92
Purity (%): 98

,CLAIMS:We Claim:
1. A process for the preparation of a compound of Formula I having purity greater than 97%, comprising;
a) reacting a compound of Formula II with bromine to obtain the compound of Formula I having purity greater than 97%; and
b) isolating the compound of Formula I having purity greater than 97% from step a).

Formula I

Formula II

2. The process as claimed in claim 1, wherein step a) takes place at the temperature in the range of 10oC to 58oC.
3. A process of preparation of a compound of Formula II, comprising:
a) reacting a compound of Formula III with an organic base in the presence of water to obtain the compound of Formula II,
b) isolating the compound of Formula II from step b).

Formula II

Formula III

4. The process as claimed in claim 3, wherein the step a) is carried out at a temperature in the range of 20oC to 60oC.

5. The process as claimed in claim 3, wherein the step a) is carried out in the presence of polymerization inhibitors selected from 2,6-Bis(1,1-dimethylethyl)-4-methylphenol (BHT), methyl hydroquinone, hydroquinone and phenothiazine or mixture thereof.

6. A process of preparation of a compound of Formula I, comprising:
a) reacting a compound of Formula III with an organic base to obtain a compound of Formula II,
b) optionally, isolating the compound of Formula II from step a),
c) contacting bromine with step a) or b) to obtain a compound of Formula I, and
d) isolating the compound of Formula I form step c)

7. The process as claimed in claim 6, wherein step a) is carried out at a temperature in the range of 20oC to 60oC and the step c) is carried out at a temperature in the range of 10oC to 58oC.

8. The process as claimed in claim 1 or claim 6, wherein the isolation of the compound of Formula I is carried out by distillation, evaporation, decantation and layer separation or mixture thereof.