PROCESS FOR THE PREPARATION OF ALKYLFULOROACRYLATES
Field of the invention
The present invention provides a process for the preparation of alkylfluoroacrylates of
Formula I.
Background of the invention
In the past, crossed Claisen condensation of alkyl monofluoroacetates with esters of formic
acid in the presence of strong bases is carried out. Further, followed by reaction with
paraformaldehyde results in the formation of α-fluoroacrylates. The U.S Patent No. 3,262,968
and PCT Publication No. WO 2014/001365 provide the methods of preparation of
alkylfluoroacrylates.
The PCT Publication No. WO 2014/001365 provides the use of alkane solvent, especially
hexane and pentane for the crossed Claisen condensation.
F
O
CH2
O
R
Formula I
Wherein R is C1-6 alkyl group
It is, therefore, a principal object of the present invention to prepare alkylfluoroacrylates,
especially methyl-2-fluoroacrylate, in good yield and purity. The present invention provides a
process for the preparation of compound of Formula I, which is simple, easy to perform and
industrially doable.
Summary of the invention
The present invention provides a process for the preparation of compound of Formula I
comprising;
a) reacting an alkylfluoroacetate with an ester of oxalic acid in the presence of a base
and methylene chloride,
2
b) the step a) mixture reacted with paraformaldehyde to obtain compound of Formula I,
and
F
O
CH2
O
R
Formula I
Wherein R is C1-6 alkyl group
c) isolating a compound of Formula I from step b) reaction mixture.
Detailed description of the invention
The present invention provides a process for the preparation of compound of Formula I
comprising;
a) reacting an alkylfluoroacetate with an ester of oxalic acid in the presence of a base
and methylene chloride,
b) the step a) mixture reacted with paraformaldehyde to obtain compound of Formula I,
and
F
O
CH2
O
R
Formula I
Wherein R is C1-6 alkyl group
c) isolating a compound of Formula I from step b) reaction mixture.
The alkylfluoroacetate may be obtained commercially or prepared by the process as known in
the prior art.
The “alkyl” is univalent group, having the general formula CnH2n+1. In present invention n =
1 to 6.
The step a) is carried out at a temperature of about 20oC to 50oC and step b) is carried out in
the temperature range of -5oC to 30oC for about 2 hours to about 8 hours.
3
The compound of Formula I is isolated by any of the methods in the art, for example, crystallization, re-crystallization, distillation, evaporation and layer separation or mixture thereof.
The compound of formula I, as obtained by the present invention, has purity of about greater than 95%, preferably greater than 98%.
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
Dimethyl oxalate (154 g) and sodium methoxide (100 g) were mixed in methylene chloride at room temperature. A solution of Methyl fluoroacetate (100 g, 1.09 mole) in methylene chloride was added to above reaction mixture at in 4-5 hrs. After stirring the reaction mixture for 7-8 hrs, it was cooled to -10 °C and paraformaldehyde (49g) was added at-10 to -15 °C and stirred till reaction completion. Reaction mixture was cooled to -5 to -8 °C and added slowly to dilute sulphuric acid (1500 g, 10%). Heated the reaction mixture to 10 °C and separated the organic layer. The aqueous layer was further extracted with methylene chloride. The organic layers were washed with 10 % Na2CO3 (250.5g). Added BHT as stabilizer and distilled to get pure methyl 2-fluoroacrylate (53g).

We claim:
1. A process for the preparation of compound of Formula I comprising;
a) reacting an alkylfluoroacetate with an ester of oxalic acid in the presence of a base
and methylene chloride,
b) the step a) mixture reacted with paraformaldehyde to obtain compound of Formula I,
and
F
O
CH2
O
R
Formula I
Wherein R is C1-6 alkyl group
c) isolating a compound of Formula I from step b) reaction mixture.
2. The process as claimed in claim 1, wherein step a) is carried out in a temperature
range of 20oC to 50oC.
3. The process as claimed in claim 1, wherein step b) is carried out in a temperature
range of -5oC to 30oC.
4. The process as claimed in claim 1, wherein the compound of Formula I is isolated by
any of the methods selected from crystallization, re-crystallization, distillation,
evaporation and layer separation or mixture thereof.
5. The compound of formula I, as obtained by the process as claimed in claim 1, has
purity of about greater than 95%, preferably greater than 98%.