PROCESS FOR THE PREPARATION OF FLUOROACRYLIC ACID ESTERS
Field of the invention
The present invention provides a process for the preparation of methyl 2-fluoroacrylate of
Formula VI.
Background of the invention
The methyl 2-fluoroacrylate (MFA) of Formula VI is a key intermediate for agrochemicals and
pharmaceuticals. Crossed Claisen condensation of alkyl monofluoroacetates with esters of formic acid
or oxalic acid in the presence of strong bases, followed by a reaction with paraformaldehyde represents
one of the most widely used methods for the synthesis of α-fluoroacrylates.
F
H2C
O
CH3
O
Formula VI
The PCT publication no. WO 2014/034906 relates to a method for producing α-fluoroacrylic
acid ester having the formula H2C:CFCO2R, wherein, R represents the alkyl group that may be
substituted by one or more fluorine atoms. The α-fluoroacrylic acid ester is obtained by reacting a
compound having the formula H2C:CFX, wherein X is Br or Cl, with an alcohol and carbon monoxide
in the presence of a transition metal catalyst and a base.
The PCT publication no. WO 2014/001365 provides a process for the manufacture of an
alkylfluoroacrylate, by reacting an alkylfluoroacetate with an ester of formic acid or oxalic acid in the
presence of a base in a crossed Claisen condensation resulting in a Claisen salt. The Claisen salt is
reacted with paraformaldehyde to isolate alkylfluoroacrylate, using an alkane as solvent. The process
disclosed suffers from the disadvantages that the isolated MFA contains residual methyl fluoroacetate
and solvents. Purification of MFA from starting material, residual solvents and side-products is difficult
because of very close boiling points and careful column vacuum distillation is required. Also, the
starting material methyl monofluoro acetate is highly toxic and hence there is difficulty in handling at
the industrial level.
It is therefore, an object of the present invention to provide an improved process for the
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preparation of methyl 2-fluoroacrylate with high purity and high yield. The present invention provides
a process of preparation of methyl 2-fluoroacrylate which is simple, economically viable and
industrially doable, due to easy isolation of methyl 2-fluoroacrylate in comparison to prior arts.
Object of the invention
An object of the present invention is to provide a process for the preparation of a compound of
Formula VI
O
O
F
Formula VI
Summary of the invention
The present invention provides a process for the preparation of a compound of Formula VI,
comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide to
produce a compound of Formula II;
b) reacting the compound of Formula II with an organic base to produce a compound of
Formula III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula IV;
d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a
compound of Formula V;
e) reacting the compound of Formula V with zinc to produce the compound of Formula VI;
and
f) isolating the compound of Formula VI from step e)
O
O
O
O
Cl
Cl
O
O
Cl
Formula I Formula II Formula III
4
O
O
Cl
Br
Br
O
O
Cl
Br
F
O
O
F
Formula IV Formula V Formula VI
In an aspect, the present invention provides a process for the preparation of a compound of
Formula VI, comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide to
produce a compound of Formula II;
b) reacting the compound of Formula II with an organic base to produce a compound of
Formula III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula IV;
d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a
compound of Formula V;
e) reacting the compound of Formula V with zinc to produce the compound of Formula VI,
f) isolating the compound of Formula VI from step e),
wherein, optionally isolating compound of Formula II from step a), compound of Formula
III from step b), compound of Formula IV from step c) and compound of Formula V from
step d).
In another aspect, the present invention provides a process for the preparation of compound of
Formula VI,
a) reacting a compound of Formula V with zinc to give the compound of Formula VI; and
b) isolating the compound of Formula VI from step a)
Detailed description of the invention
The present invention provides a process for the preparation of a compound of Formula VI,
comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide
to produce a compound of Formula II;
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b) reacting the compound of Formula II with an organic base to produce a compound of
Formula III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula
IV;
d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a
compound of Formula V;
e) reacting the compound of Formula V with zinc to produce the compound of Formula VI;
and
f) isolating the compound of Formula VI from step e)
O
O
O
O
Cl
Cl
O
O
Cl
Formula I Formula II Formula III
O
O
Cl
Br
Br
O
O
Cl
Br
F
O
O
F
Formula IV Formula V Formula VI
In an aspect, the present invention provides a process for the preparation of a compound of Formula
VI, comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide to
produce a compound of Formula II;
b) reacting the compound of Formula II with an organic base to produce a compound of Formula
III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula IV;
d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a
compound of Formula V;
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e) reacting the compound of Formula V with zinc to produce the compound of Formula VI,
f) isolating the compound of Formula VI from step e),
wherein, optionally isolating compound of Formula II from step a), compound of Formula III from step b), compound of Formula IV from step c) and compound of Formula V from step d).
The step a) may be carried out at a temperature in the range of 10oC to 50oC. The step b) may be carried out at a temperature in the range of 5oC to 60oC. The step c) may be carried out at a temperature in the range of 10oC to 58oC. The step d) may be carried out at a temperature in the range of 15oC to 40oC. The step e) may be carried out at a temperature in the range of 55oC to 100oC.
The step b) 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 organic base may be selected from triethyl amine, diethyl amine, trimethyl amine and other organic base as 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 solvent may be selected from bromine, perfluorinated solvents or a mixture thereof. The perfluorinated solvent may be selected from perfluoro 2-methyl pentane, perfluorohexane, perfluoromethyl cyclohexane.
The compound of Formula I may be obtained commercially or may be prepared by any of the methods known in the art, for example, as in the U.S. Patent no. 3,925,463.
In another aspect, the present invention provides a process for the preparation of compound of Formula VI,
a) reacting the compound of Formula V with zinc to give the compound of Formula VI; and
b) isolating the compound of Formula VI from step a)
The step a) is carried out at a temperature in the range of 55oC to 100oC.
The step a) may be carried out in the presence of water and sulphuric acid.
The isolation of the compound of Formula VI is carried out by distillation, evaporation, and layer separation or mixture thereof.
The compound of Formula VI, obtained by the process of the present invention has a purity greater than 90% by gas chromatography, preferably greater than 93%.
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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-dichloropropanoate
Methyl acrylate (2366 g, 27.5 mol) and dimethylformamide (DMF) (40 g, 0.55 mol) was placed in a 3-liter three necked flask fitted with a stirrer, thermometer, inlet tube and gas trap. Chlorine (950 g, 0.48 mol) was passed into the methyl acrylate rapidly over a period of ten hours while the temperature was kept below 40°C. Reaction progress was monitored by gas chromatography (GC). When it seemed that 50 percent of chlorine was consumed, the reaction was stopped. The reaction mass was taken for distillation to separate methylacrylate and Methyl 2,3-dichloropropanoate. The contents were subjected to vacuum distillation. Methyl 2,3-dichloropropanoate was collected distilling at 70°C with 15mm.
Yield (%):77.2
Purity (%) = 98
Example 2: Preparation of methyl 2-chloropropenoate
Methyl 2,3-dichloropropanoate (200 g, 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-dichloropropanoate for 0.50 hours . The temperature of the reaction is maintained between 20 to 25oC . 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-chloropropenoate.
Yield (%): 93.12
Purity (%): 97.5
Example 3: Preparation of methyl 2,3-dibromo-2-chloropropanoate
Methyl 2-chloropropenoate (496 g, 4.13 mol) and BHT (3.65 g, 0.016 mol) were taken into the reaction vessel with mechanical stirrer. Bromine (670 g, 4.18 mol) was added drop-wise to the vessel while
8
keeping the temperature below 40°C to obtain methyl 2,3-dibromo-2-chloropropanoate. Progress of the reaction was monitored by gas chromatography.
Yield (%): 92
Purity (%): 98
Example 4: Preparation of methyl 3-bromo-2-chloro-2-fluoropropanoate
Methyl 2,3-dibromo-2-chloropropanoate (400g, 1.43mol) and 600g of bromine were added into a reaction vessel fitted with a stirrer. Then, BrF3/Br2 (175g, 1.28mol) was added to the reaction mass slowly at 20°C. Progress of the reaction was monitored by gas chromatography. After completion of the reaction, the reaction mass was subjected to distillation to remove the excess bromine and washed with saturated sodium meta-bisulfite solution to give the crude product. The crude product was further purified by distillation at 58°C and 10mm of mercury pressure to give methyl 3-bromo-2-chloro-2-fluoropropanoate as a colorless liquid.
Yield (%): 70
Purity (%): 97
Example 5: Preparation of methyl 2-fluoroacrylate
Zinc (6g, 0.092 mol), water (20g, 1.11 mol), con. H2SO4 (0.2g, 0.002 mol) and phenothiazine (0.5g, 0.0025 mol) were added sequentially in a reaction vessel. The reaction mixture was heated to 82°C to 86°C and methyl 3-bromo-2-chloro-2- fluoropropanoate (15 g, 0.068 mol) was added to the reaction mass slowly over a period of 20 minutes. An azeotropic mixture was distilled off at 55°C and 550 mbar simultaneously. Then, 10 ml saturated calcium chloride solution was added to the azeotropic mixture and the organic layer was separated and dried to give methyl 2-fluoroacrylate as a clear colorless liquid.
Yield (%): 85
Purity (%): 94
Example 6
(a) 500g Methyl Acrylate (5.81 mol), 8.48g DMF (0.116 mol) and 2.55g BHT were charged into a 1000ml 4- neck round bottom flask fitted with a mechanical stirrer and a double walled reflux condenser. The Reaction mass was cooled under stirring to 18˚C by using cold water. After reaching the required temperature, 430g (6.056 mol) of chlorine was purged into the reaction mass for 600 minutes at 25-40˚C. After the completion of reaction, chlorine purging was stopped and N2 gas was passed to
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give a pale yellow liquid.
(b) 844g of pale yellow liquid obtained from above step 1(a), 919g Water and 2.27g BHT were charged into 3000ml 4- neck round bottom flask fitted with a mechanical stirrer and a double walled condenser. The Reaction mass was cooled under stirring to 18˚C by using cold water. After reaching the required temperature, 532g (5.27 mole eq.) of triethylamine was added to the reaction mass for 5 hours at 25-40˚C under stirring. After completion of reaction, the organic layer was separated to give the mixture weighing 604g.
(c) 206g (1.3 mol.) of Bromine was charged into a 250ml 3-neck Round bottom flask fitted with magnetic stirrer and double walled condenser. Then the reaction mass was heated slowly 40 ˚C by using a water bath and 150g (1.2 mol) of the mixture obtained from 2(b) was added to the reaction mass for 45 minutes under stirring at 40-60 ˚C. After the completion of reaction, N2 gas was passed to give methyl 2,3-dibromo-2-chloropropanoate, weighing 322g. The reaction was monitored by GC and the results are as shown below.
Purity: 95.4% (GC area %)
Yield: 90%

We Claim:
1. A process for the preparation of a compound of Formula VI, comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide to
produce a compound of Formula II;
b) reacting the compound of Formula II with an organic base to produce a compound of
Formula III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula IV;
d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a
compound of Formula V;
e) reacting the compound of Formula V with zinc to produce the compound of Formula VI;
and
f) isolating the compound of Formula VI from step e)
O
O
O
O
Cl
Cl
O
O
Cl
Formula I Formula II Formula III
O
O
Cl
Br
Br
O
O
Cl
Br
F
O
O
F
Formula IV Formula V Formula VI
2. A process for the preparation of a compound of Formula VI, comprising;
a) reacting a compound of Formula I with chlorine in the presence of dimethyl formamide to
produce a compound of Formula II;
b) reacting the compound of Formula II with an organic base to produce a compound of
Formula III;
c) reacting the compound of Formula III with bromine to produce a compound of Formula IV;
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d) reacting the compound of Formula IV with bromine trifluoride in a solvent to produce a compound of Formula V;
e) reacting the compound of Formula V with zinc to produce the compound of Formula VI, and
f) isolating the compound of Formula VI from step e)
wherein, optionally isolating compound of Formula II from step a), compound of Formula III from step b), compound of Formula IV from step c) and compound of Formula V from step d).
3. The process as claimed in claim 1 or 2, wherein the step a) is carried out at a temperature in the range of 10oC to 50oC.
4. The process as claimed in claim 1 or 2, wherein the step b) is carried out at a temperature in the range of 5oC to 60oC.
5. The process as claimed in claim 1 or 2, wherein the step b) is carried out in the presence of polymerization inhibitors selected from the group consisting of 2,6-bis(1,1-dimethylethyl)-4-methylphenol (BHT), methyl hydroquinone, hydroquinone, and phenothiazine or mixture thereof.
6. The process as claimed in claim 1 or 2, wherein the organic base is selected from the group consisting of triethyl amine, diethyl amine, and trimethyl amine or mixture thereof.
7. The process as claimed in claim 1 or 2, wherein the solvent is selected from the group consisting of perfluoro 2-methyl pentane, perfluorohexane and perfluoromethyl cyclohexane or mixture thereof.
8. A process for the preparation of compound of Formula VI,
a) reacting the compound of Formula V with zinc to give the compound of Formula VI; and
b) isolating the compound of Formula VI from step a).
9. The process as claimed in claim 8, wherein the step a) is carried out in the presence of water and sulphuric acid.
10. The process as claimed in claim 1, 2 or 8, wherein the isolation of the compound of Formula VI is carried out by distillation, evaporation, and layer separation or mixture thereof.