Field of the invention
The present invention provides a process for the preparation of methyl fluoroacrylate of
Formula I.
F
H2C
O
CH3
O
Formula I
Background of the invention
The methyl fluoroacrylate (MFA) of Formula I 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 I
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
2
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 solvent. The process disclosed suffers from the disadvantages that the isolated MFA
contains residual methyl fluoroacetate and solvents. The 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
preparation of methylfluoroacrylate with high purity in high yield and easy isolation. The
present invention provides a process of preparation of methylfluoroacrylate 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,
comprising;
a) contacting a compound of Formula II with a compound of Formula III in the presence
of zinc to obtain a compound of Formula I;
b) isolating the compound of Formula I from step a).
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
The present invention also provides a process for the preparation of a compound of Formula
I, comprising;
a) contacting a compound of Formula IV with chlorine or a source of chlorine to obtain
a compound of Formula II;
3
b) contacting a compound of Formula V with Bromine and antimony trifluoride to obtain
a compound of Formula III;
c) contacting the compound of Formula II with the compound of Formula III in the
presence of zinc to obtain a compound of Formula I;
d) isolating the compound of Formula I from step c)
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
F3C O
CH3
O
Cl3C O
CH3
O
Formula IV Formula V
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 a compound of Formula III in the presence
of zinc to obtain a compound of Formula I;
b) isolating the compound of Formula I from step a).
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
The compound of Formula II may be prepared by any method known in the art, for example,
2937/DEL/2015 or may be obtained commercially. The compound of Formula III may be
4
prepared by any method known in the art, for example, JP 04-036262 or may be obtained
commercially
The step a) of present invention is carried out in the presence of polymerization inhibitors.
The polymerization inhibitor is selected from the group consisting of butylated toluene,
methyl hydroquinone, hydroquinone, phenothiazine and other polymerization inhibitors
known in the art.
The present invention also provides a process for the preparation of a compound of Formula
I, comprising;
a) contacting a compound of Formula IV with chlorine or a source of chlorine to obtain
a compound of Formula II;
b) contacting a compound of Formula V with Bromine and antimony trifluoride to obtain
a compound of Formula III;
c) contacting the compound of Formula II with the compound of Formula III in the
presence of zinc to obtain a compound of Formula I;
d) isolating the compound of Formula I from step c)
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
F3C O
CH3
O
Cl3C O
CH3
O
Formula IV Formula V
The compound of Formula IV may be reacted with chlorine at a temperature in the range of
30oC to 75oC. The source of chlorine may be selected from molecular chlorine. The
chlorination takes place in the presence of light source, in particular visible light or ultraviolet
light in a range of from 450 to 260 nm.
5
The step c) of present invention is carried out in the presence of polymerization inhibitors. The polymerization inhibitor is selected from the group consisting of butylated toluene, methyl hydroquinone, hydroquinone, phenothiazine and other polymerization inhibitors known in the art.
The isolation of the compound of Formula I is carried out by distillation, evaporation, decantation and layer separation or mixture thereof.
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.
Example
Preparation of Methyl Fluoroacrylate
Zinc (1.38 mol), cuprous chloride (0.04 mol), phenothiazine (0.15 mol) and dimethyl formamide (4.61 mol) were taken in a reaction vessel. The temperature of the reaction mass was raised to 60°C. The mixture of chloromethyl trifluoroacetate (0.537 mol) and methyldichlorofluoro acetate (0.543 mol) was added slowly to the reaction mass at 50°C . The addition rate was maintained in such a way that the temperature of the reaction mass should not exceed 55 oC. The reaction mass was subjected to distillation under vacuum 50 oC at 5 mm/hg to obtain the title compound.

We claim:
1. A process for the preparation of a compound of Formula I, comprising;
a) contacting a compound of Formula II with a compound of Formula III in the presence
of zinc to obtain a compound of Formula I;
b) isolating the compound of Formula I from step a).
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
2. The process as claimed in claim 1, wherein step a) is carried out in the presence of a
polymerization inhibitor.
3. The process as claimed in claim 2, wherein the polymerization inhibitor is selected
from the group consisting of butylated toluene, methyl hydroquinone, hydroquinone
and phenothiazine or mixture thereof.
4. A process for the preparation of a compound of Formula I, comprising;
a) contacting a compound of Formula IV with chlorine or a source of chlorine to obtain
a compound of Formula II;
b) contacting a compound of Formula V with Bromine and antimony trifluoride to obtain
a compound of Formula III;
c) contacting the compound of Formula II with the compound of Formula III in the
presence of zinc to obtain a compound of Formula I;
d) isolating the compound of Formula I from step c)
F3C O
CH2Cl
O
Cl2FC O
CH3
O
F
H2C
O
CH3
O
Formula II Formula III Formula I
7
F3C O
CH3
O
Cl3C O
CH3
O
Formula IV Formula V
5. The process as claimed in claim 4, wherein step a) takes place at a temperature in the
range of 30oC to 75oC.
6. The process claimed in claim 4, wherein the source of chlorine in step a) is molecular
chlorine.
7. The process as claimed in claim 4, wherein the step c) is carried out in the presence of
a polymerization inhibitor selected from the group consisting of butylated toluene,
methyl hydroquinone, hydroquinone and phenothiazine or mixture thereof.
8. The process as claimed in claim 1 or 4, wherein the isolation of the compound of
Formula I is carried out by distillation, evaporation, decantation and layer separation
or mixture thereof.