Field of the invention
The present invention relates to a process for the synthesis of alkenone ethers.
Background of the invention
The alkenone ethers, such as 4-alkoxy- 1, 1, 1 -trifluoro-3-butenone, are building blocks and
important precursors for chemical synthesis of agrochemicals or pharmaceuticals.
The U.S. Patent No. 5,708,175 provides a process for the preparation of halogenated alkenone
ethers by reacting an acid chloride with vinyl ether in the presence of a base at a very low
temperature ranging from 2OC to 5OC.
The U.S. Patent No. 7,057,079 provides a process for production of alkenones from vinyl ethers
and acid halides or acid anhydrides in the presence of "onium" salt of carboxylic acid.
The U.S. Patent No. 7,405,328 provides a two-step method for production of alkenones
comprising addition of carboxylic acid halides to vinyl ethers in the absence of acid-capturing
agent and at high temperatures up to 1 50°C.
The U.S Patent No. 8,440,865 provides a two-step process for preparation of alkenone providing
a halogenated precursor of the alkenone and eliminating the hydrogen halide from said precursor
to form the alkenone by a thermolysis treatment selected from the group consisting of a
thermolysis carried out at a temperature from greater than 90°C to 120°C, a flash thennolysis,
vacuum thermolysis carried out at a temperature from 60°C to 140°C, and thermolysis under
stripping with inert gas.
The present invention now makes available an improved process for the preparation of alkenone
ethers, in particular concerning the selectivity and the yield of the production, whereby, amongst
others, separation of the product can be simplified and yield loss is minimized. The present
invention further obviates stringent reaction conditions such as very low reaction temperatures
and multiple steps.
Surnrnarv of the invention
The present invention relates to a process for the synthesis of alkenone ethers.
In one aspect, the present invention provides a process for preparation of alkenone ether of
Formula I, comprising;
Formula I
wherein R' represents a Cl-Clo alkyl group which is substituted by at least one halogen atom;
R~ represents aryl, substituted aryl, or a Cl-Clo alkyl group which is optionally substituted by
at least one halogen atom;
a) reacting a compound of Formula I1 and compound of Formula 111, and
Formula I1 Formula 111
wherein X represents fluorine, chlorine, iodine or bromine; R1 represents a C 1 -C lo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a Cl-Clo alkyl group which is optionally substituted by at least one halogen atom;
b) isolating alkenone ether of Formula I, wherein step a) is carried out at a pressure of at
least about 3 kg/cm2 or more.
In second aspect, the present invention provides a process for preparation of alkenone ether of
Formula I having purity greater than 98%, comprising;
Formula I
wherein R' represents a CI-Cloa lkyl group which is substituted by at least one halogen atom;
R' represents aryl, substituted aryl, or a CI-Cloa lkyl group which is optionally substituted by
at least one halogen;
a) reacting a compound of Formula I1 and compound of Formula 111, and
Formula I1 Formula I11
wherein X represents fluorine, chlorine, iodine or bromine; R' represents a Cl-Clo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a CI-Clo alkyl group which is optionally substituted by at least one halogen atom;
b) isolating alkenone ether of Formula I having purity greater than 98%, wherein step a) is
carried out at a pressure of at least about 3 kgicm2 or more.
The Gas chromatography is carried out with Agilent technologies-6820 with FID detector.
Detailed Description of the Invention
In an embodiment, the present invention provides a process for preparation of alkenone ether of
Formula I, comprising;
Formula I
wherein R' represents a CI-Cloa lkyl group which is substituted by at least one halogen atom;
R' represents aryl, substituted aryl, or a CI-Cloa lkyl group which is optionally substituted by
at least one halogen atom;
a) reacting a compound of Formula I1 and compound of Formula 111, and
Formula I1 Formula 111
wherein X represents fluorine, chlorine, iodine or bromine; R' represents a CI-Clo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a Cl-Cloa lkyl group which is optionally substituted by at least one halogen atom;
b) isolating alkenone ether of Formula I, wherein step a) is carried out at a pressure of at
least about 3 kgicm2 or more.
In another embodiment, the present invention provides a process for preparation of alkenone
ether of Formula I having purity greater than 98%, comprising;
Formula I
wherein R' represents a CI-Clo alkyl group which is substituted by at least one halogen atom;
R~ represents aryl, substituted aryl, or a C1-Clo alkyl group which is optionally substituted by
at least one halogen atom;
a) reacting a compound of Formula I1 and compound of Formula 111, and
Formula I1 Formula 111
wherein X represents fluorine, chlorine, iodine or bromine; R' represents a Cl-Clo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a CI-Clo alkyl group which is optionally substituted by at least one halogen atom;
b) isolating alkenone ether of Formula I having purity greater than 98%, wherein step a) is
carried out at a pressure of at least about 3 kg/cm2 or more.
Unless specifically limited otherwise, the term "alkyl" as used therein, includes straight chain,
branched chain and cyclic groups. Thus, typically alkyl groups are methyl, ethyl, n-propyl,
isopropyl and cyclopropyl. The halogen may be selected from fluorine, chlorine, bromine and
iodine.
The reaction of compound of Formula I1 and compound of Formula 111 may optionally take place
in the presence of base. The base may be an organic base or inorganic base. The organic base
may be selected from a nitrogen-containing heterocyclic compound such as pyridine, quinolone
or picoline and mixture thereof; a tertiary base such as triethylamine, dimethylaniline,
diethylaniline or 4-dimethylaminopyridine and mixture thereof. The inorganic base may be
selected from alkali metal hydroxides such as sodium hydroxide, potassium hydroxide or cesium
hydroxide and mixture thereof; alkali metal carbonates such as sodium carbonate, potassium
carbonate or cesium carbonate and mixture thereof; alkali metal bicarbonate such as sodium
bicarbonate or potassium bicarbonate and mixture thereof; alkaline metal hydroxides such as
calcium hydroxide, magnesium hydroxide or barium hydroxide and mixture thereof; alkaline
metal carbonates such as calcium carbonate, magnesium carbonate or barium carbonate and
mixture thereof.
The reaction of compound of Formula I1 and compound of Formula I11 may optionally take place
in the presence of organic solvent. The organic solvent may be selected from aromatic
hydrocarbon such as benzene, toluene or xylene and mixture thereof; an aliphatic hydrocarbon
such as pentane or hexane and mixture thereof; a halogenated hydrocarbon such as methylene
chloride, chloroform, ethylene chloride or carbon tetrachloride and mixture thereof; an ether such
as diethyl ether, dibutyl ether, tetrahydrohran or dioxane and mixture thereof.
The reaction of compound of Formula I1 and Formula 111 is carried out at a pressure of at least
about 3 kg/cm2 or more, for example, at a pressure of about 3 kg/cm2 to about 15 kg/cm2.
The reaction of compound of Formula I1 and Formula 111 may be carried out a temperature of
about 5°C to about 80°C, for example at about 5°C to about 60°C for about 5 minutes to about 3
hours, for example for about 15 minutes to about 1 hour.
The compound of Formula I is isolated by any of the methods in the art, for example,
evaporation, decantation, distillation, filtration or layer separation and mixture thereof. The
compound of Formula I has a purity greater than 98% 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.
Preparation of 4-Ethoxv- 1 , 1 ,l -trifluoro-3-buten-2-one
Ethyl vinyl ether (60 g) and triethyl amine (28 g) were taken in an autoclave. The vessel was
cooled to 10°C to 15OC and the contents were stirred. The trifluoroacetyl fluoride (99 g) was
added in parts to the vessel through dip line from the stainless steel cylinder at 30°C to 40°C and
5 to 10 kg/cm2 pressure. The contents were stirred for 30 minutes and the reactor pressure drops
to 0.25 to 0.5 kg/cm2. The excess of trifluoroacetyl fluoride was removed and the contents were
washed with water. The organic layer is separated, concentrated to obtain the title product.
Yield (%): 86.2
Purity (%): 98.2
We claim:
1. A process for preparation of alkenone ether of Formula I, comprising;
R I -c(o)-CH=CH- OR^
Formula I
wherein R' represents a CI-Cloa lkyl group which is substituted by at least one halogen atom;
R2 represents aryl, substituted aryl, or a C,-Clo alkyl group which is optionally substituted by
at least one halogen atom;
a) reacting a compound of Formula I1 and compound of Formula 111, and
R' -C(O)X CH~=C(H)-OR~
Formula I1 Formula 111
wherein X represents fluorine, chlorine, iodine or bromine; R' represents a Cl-Clo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a CI-Clo alkyl group which is optionally substituted by at least one halogen atom;
b) isolating alkenone ether of Formula I,
wherein step a) is carried out at a pressure of at least about 3 kg/cm2 or more.
2. A process for preparation of alkenone ether of Formula I having purity greater than 98%,
comprising;
R~-C(O)-CH=CH-OR~
Formula I
wherein R' represents a CI-Clo alkyl group which is substituted by at least one halogen atom;
R2 represents aryl, substituted aryl, or a C1-Clo alkyl group which is optionally substituted by
at least one halogen atom;
a) reacting a compound of Formula I1 and compound of Formula 111, and
Formula I1 Formula I11
wherein X represents fluorine, chlorine, iodine or bromine; R' represents a CI-Clo alkyl
group which is substituted by at least one halogen atom and R2 represents aryl, substituted
aryl, or a CI-Clo alkyl group which is optionally substituted by at least one halogen atom.
b) isolating alkenone ether of Formula I having purity greater than 98%, wherein . step a)
is carried out at a pressure of at least about 3 kg/cm2 or more.
3. The process of claim 1 or 2, wherein step a) takes place in the presence of organic base or
inorganic base.
4. The process of claim 3, wherein the organic base is selected from pyridine, quinolone,
picoline, triethylamine, dimethylaniline, diethylaniline or 4-dimethylaminopyridine and
mixture thereof.
5. The process of claim 3, wherein the inorganic base is selected from sodium hydroxide,
potassium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, cesium
carbonate, sodium bicarbonate, potassium bicarbonate, calcium hydroxide, magnesium
hydroxide, barium hydroxide, calcium carbonate, magnesium carbonate or barium
carbonate and mixture thereof.
6. The process of claim 1 or 2, wherein step a) takes place in the presence of organic solvent
selected from benzene, toluene, xylene, pentane, hexane, methylene chloride, chloroform,
ethylene chloride, carbon tetrachloride, diethyl ether, dibutyl ether, tetrahydrofuran or
dioxane and mixture thereof.
7. The process of claim 1, wherein the compound of Formula I has a purity greater than
98% by gas chromatography.
8. The process of claim 1 or 2, wherein step a) is carried out at the temperature of about 5°C
to about 80°C.
Dated this 26th day of July, 2013.
(Rame k C. Dhawan)
of La11 Lahiri & Salhotra
Agents for the Applicant