Process for the manufacture of halogenated precursors of alkenones and of
alkenones
This application claims priority to European application 11195352.7
filed on 22 Dec 201 1, the whole content of this application being incorporated
herein by reference for all purposes.
The present invention relates to a process for preparing halogenated
precursors of an alkenone, to a process for preparing alkenones from the
halogenated precursors obtained thereby, to method for transporting or storing
the aforesaid products.
Halogenated alkenones, such as 4-ethoxy-l,l,l-trifluoro-3-butenone
(ETFBO), are building blocks in chemical synthesis, as disclosed, for example,
in U.S. Pat. No. 5,708,175.
WO-A-201 1/003854 in the name of the applicant, the entire contents of
which is incorporated by reference into the presents, discloses inter alia
manufacture of halogenated precursors of an alkenone, carried out in a ceramic
lined vessel.
It is an object of the present invention to provide an improved process for
the preparation of halogenated precursors of alkenones. It is another object of
the present invention to provide a process for the manufacture of alkenones from
the halogenated precursors.
The invention relates consequently to a process for preparing a halogenated
precursor of an alkenone, which comprises reacting a carboxylic acid halide with
a vinyl ether in a liquid reaction medium using an equipment having at least one
surface in contact with the liquid reaction medium, wherein said surface consists
of a material selected from a nickel based alloy, containing at least 14 % wt.
molybdenum relative to the total weight of the alloy and 14 % wt. of chromium
relative to the total weight of the alloy ; glass and polytetrafluoroethylene.
It has been found that the process according to the invention allows for
efficient manufacture of halogenated precursors of an alkenone while
substantially avoiding corrosion of the equipment used and consequently
enhancing the plant life and reducing downtimes. In certain aspects of the
invention, it is particularly surprising that the highly reactive reagents and
products of the reaction can be processed substantially without unwanted sidereactions
in an equipment containing transition metals, which are known to
catalyze a lot of chemical reactions. It has also been found, surprisingly, that
alpha-CF3-ketones, which can be prone to metal-complexation reactions, can be
advantageously prepared in equipment made of certain alloys.
Particular alloys in the sense of this invention correspond to the
specifications according to ASME SB-575.
In the process according to the invention, the alloy preferably contains
nickel, in an amount from 50 to 7 1 wt %, relative to the total weight of the alloy.
Other components include chromium, preferably in an amount from 14
to 20 wt %, relative to the total weight of the alloy, and molybdenum, preferably
in an amount from 14 to 20 wt %, relative to the total weight of the alloy, the
remainder of the alloy consisting essentially of other metals, in particular
transition metals. Said other metals may contain up to 3 % wt. of iron, up
to 2 % wt. of cobalt and up to 1% wt of manganese, all relative to the total
weight of the alloy. More preferably, the alloy is selected from Haste oy® C
alloys, for example from the group consisting of Hastelloy® C4, C22 and C276.
In the process according to the invention, the equipment is generally
selected from the group consisting of a vessel, a tube, a nozzle, in particular
suitable for feeding of reactants, a tank, a stirrer, a heat exchanger, a distillation
column or combinations thereof.
It has been found that in the process according to the present invention for
preparing an alkenone can advantageously be carried out in a microreactor, at
least partially.
Microreactors are known in the art (cf. e.g. WO 2007/042313 A2,
US 2009/0295005 Al , EP 1 481 724 A2, or WO 2007/027785 A2).
"Microreactors" as used herein is understood in the broadest technical
meaningful sense. In the art often "micromixer" and "microreactor" are used as
synonyms. In some cases, however, a microreactor which mixes a plurality of
fluids together is called a "micromixer" and a microreactor which causes a
chemical reaction during the mixing of a plurality of fluids is called a
"microreactor". The microreactor as used herein is a device comprising
"micromixers", "microreactors" and combinations of these as used in the art.
Preferably, "microreactor" as used herein is a device which comprises
components, typically channels or flow ducts, having characteristic/determining
geometric dimensions of 1 mih to 2000 mih, and in particular preferable
from 10 mih to 1000 mih. A microreactor is typically provided with a reaction
channel which leads to a plurality of fine reaction channels or flow ducts. The
equivalent diameter obtained in the section of the fine reaction channel is,
converted to a circle, several micrometers to several hundreds of micrometers.
Preferably, "microreactor" as used herein includes at least one micromixer,
which is preferably used in combination with a further microreactor. Further, the
term "microreactor" used herein can be a device, which is referred to in the art as
"minireactor", "micro heat exchanger", "minimixer" or "micromixer". Examples
of these are microreactors, micro heat exchangers, and T- and Y-mixers, as
available by a large number of companies (e.g. Ehrfeld Mikrotechnik
BTS GmbH, Institut fur Mikrotechnik Mainz GmbH, Siemens AG,
CPC-Cellulare Process Chemistry Systems GmbH).
As alternative micromixers, V-type mixers, as available by
Forschungszentrum Karlsruhe, split and recombine mixers, e.g. cascade mixers
or faceted mixers, as available by Ehrfeld Mikrotechnik BTS GmbH, or
caterpillar mixers, e.g. obtainable from the Institut fur Mikrotechnik, Mainz, can
be used. In these mixers the product streams to be mixed are divided into
smaller flows and these smaller flows are repeatedly combined and divided.
Further alternative micromixers with a cross-sectional constriction, such as focus
mixers or cyclone mixers, or else jet mixers, as described in EP 1 165 224 Bl,
e.g. obtainable from Synthesechemie, and impingement jet mixers or valve
mixers, as described in WO 2005/079964 Al, available from Ehrfeld
Mikrotechnik BTS GmbH, can be used. Particular preferred cascade mixers are
used as micromixers in the process of the present invention.
In one aspect, substantially all or all the surfaces of the equipment which
can come into contact with liquid reaction medium consist of a material selected
from glass and alloy in accordance with the invention. In another aspect, at least
a part of the surfaces which can come into contact with liquid reaction medium
consists of alloy in accordance with the invention. In that case, the parts which
consist of alloy in accordance with the invention are preferably located at a place
of the equipment which comes into contact with the liquid reaction medium at a
feed point of reactants or in the vicinity of such feed point, "vicinity" denoting in
particular a distance of from greater 0, in particular at least 0,1 to 50 cm of such
feed point.
In the process according to the invention, the liquid reaction medium has
generally a temperature from -50°C to 150°C.
In the process according to the invention, the equipment can be used to
manufacture a precursor of an alkenone. In this case, the temperature of the
liquid reaction medium is generally from 0°C to 50°C. Especially in this case,
the liquid reaction medium comprises hydrogen chloride and an alkenone.
In the process according to the invention, the equipment can be used to
manufacture an alkenone from the precursor of the alkenone. In this case, the
temperature of the liquid reaction medium is generally from 50°C to 150°C.
In a first particular embodiment, the equipment has the surface coated or
lined onto a support material. Suitable support materials include, for example,
steel. When the surface consists of an alloy in accordance with the invention, the
latter may be applied onto the support material by techniques such as coating,
spraying or cladding. A surface obtained by coating or cladding is preferred.
When the surface consists of polytetrafluoroethylene, high-density
polytetrafluoroethylene is preferably used. The polytetrafluoroethylene is
preferably applied onto the support material, in particular steel, by spraying.
In a second particular embodiment, the equipment consists of massive
alloy in accordance with the invention, in particular as described above.
The process according to the invention is preferably performed to prepare a
halogenated alkenone precursor of formula (I)
R1-C(0)-CH 2-CHX-OR2 (I)
wherein R1 represents a CI-CIO alkyl group which is optionally substituted by at
least one halogen atom or R1 represents CF3, CF2C1, CF2H ; and R2 represents
aryl, substituted aryl, or a CI-CIO alkyl group which is optionally substituted by
at least one halogen atom and X represents fluorine, chlorine or bromine wherein
an acid halide corresponding to Formula (II) : R1-C(0)X (II) in which X
represents fluorine, chlorine or bromine and R1 has the meaning given above, is
reacted with a vinyl ether corresponding to Formula (III) : CH2=C(H)-OR2 (III)
in which R2 has the meaning given above.
R1 is often a fluorinated C1-C4 alkyl group. R1 preferably represents
methyl, ethyl, n-propyl, isopropyl or methyl, ethyl, n-propyl or isopropyl
substituted by at least one fluorine atom. It is especially preferred if R1
represents methyl, ethyl or methyl or ethyl substituted by at least one fluorine
atom. CF3, CF2H, CF2C1, C2F , C3F7 are particularly preferred as R1. CF3,
CF2C 1 and CF2H are more particularly preferred as R1.
R2 can be selected for example from aryl, for example, phenyl,
C1-C4 alkyl groups and/or phenyl substituted by halogen atoms. R2 is often
a C1-C4 alkyl group. Preferably, R2 represents a linear or branched C1-C4 alkyl
group, and particularly preferably R2 represents methyl, ethyl, n-propyl or
isopropyl, most preferably a methyl or an ethyl group.
X is preferably selected from fluorine and chlorine, more preferably X is
chlorine.
The alkenones which can be prepared from the halogenated alkenone
precursors of formula (I) are the alkenones of formula (IV),
R1-C(0)-CH=CH-OR 2 (IV)
R1 and R2 have the same meaning as in formula (I). ETFBO is a
particularly preferred alkenone.
In the liquid reaction medium of the manufacture of the precursor of an
alkenone generally a content of hydrogen halide in the reaction medium of equal
to or lower than 1% wt is maintained. Preferably, this content is maintained
equal to or lower than 0.5 % wt. When the formation of hydrogen halide is
substantially avoided, a content of hydrogen halide in the reaction medium equal
to or higher than 0.01 % wt albeit equal to or higher than 0.1 % wt relative to the
total weight of the reaction medium is acceptable.
The process according to this specific embodiment, generally comprises
carrying out the reaction at a temperature from 0°C to 40°C, preferably
from 10°C to 30°C, more preferably at equal to or about 25°C and most
preferably at equal to or about 20°C. If desired, the reaction can also be
performed at temperatures below 0°C ; e.g., between 0°C and -50°C, but the
reaction rate is lower. It is preferred to operate at a temperature from 0°C
to 40°C.
In the process according to this specific embodiment, the reaction is
preferably carried out in a continuously stirred tank reactor (CSTR).
In a particular aspect said the continuously stirred tank reactor is combined
with a plug flow reactor. In that case, generally, at least a part of the liquid
reaction medium is withdrawn from the continuously stirred tank reactor and
subjected to further reaction in a plug flow reactor. In this case, the CSTR
reactor is usually in a turbulent state while the plug-flow reactor can be in a
turbulent or laminar flow state.
Particular embodiments of CSTR include reactors which consist of one or
more cylindrical or spherical tanks wherein a turbulent state of the liquid reaction
medium is created by any of the means described above. When more than
one CSTR reactor is used, for example 2, 3 or 4 reactors, it is advantageous to
split the feed of vinyl ether so as to feed vinyl ether to each reactor.
Particular embodiments of plug flow reactor are in the form of a cylindrical
tube through which the feed enters at one end and exits at the other end.
The addition reaction of the acid halide and the vinyl ether is exothermic.
As mentioned above, it is preferably performed at a temperature from 0°C
to 40°C, and thus, the reaction medium is preferably cooled.
In another particular aspect said the continuously stirred tank reactor is
combined with a heat exchanger. Said heat exchanger advantageously can
remove heat from the reactor during the exothermic reaction. The heat
exchanger can be a separated device added to the CSTR or the heat exchanger
and the reactor can be combined into a single piece of equipment.
Existing apparatus with intensified heat exchange and compact heat
exchanger/reactor (HEX reactor).
By way of illustration, the following devices can be used as heat
exchangers, especially when added to the CSTR : double jacket, external and
internal coils.
If the heat exchanger is a device separated from the reactor, a part of the
reaction medium can be passed through a loop via a heat exchanger or a cooling
machine. This is preferably performed continuously.
The stirrers may be single-stage or multistage embodiments, especially
those which produce not only a tangential flow component but also an axial flow
field. Preferred stirrers are those having 1 to 7 stirring blade stages attached,
preferably equidistantly, on the axial stirrer shaft. Examples are blade, anchor,
impeller, Pfaudler, disk, helical, bar, finger propeller, sigma, paddle, pitchedblade
and coaxial stirrers, such as cross-arm. Multiflow, multipulse
countercurrent, Intermig and Interpro stirrers. A suitable reactor is described
in US patent 6,428,199. The reactor described therein has a stirring mechanism,
incoming and outgoing lines and a removable head wherein both the incoming
and outgoing lines and the stirring mechanism are installed on the reactor floor.
A reactor which can be used in the process of the present invention is
described in US patent application publication 2006/0198771 Al . A cylindrical
vertical stirred reactor provided with means of injection of gaseous (or liquid)
reactants at the bottom, and, as essential parts, centrifugal turbines arranged
along a single vertical agitating shaft. The shaft is driven by a geared motor unit
which is most often situated either above or below the reactor. The reactor may
be equipped with counterbaffles and/or a heat exchanger.
In still another aspect, the process according to the invention is carried out
in a microreactor. In this embodiment, the internal surfaces of the microreactor
consist preferably of an alloy in accordance with the invention. More
information about the reaction of the present invention carried out in a
microreactor are contained in PCT/ EP201 1/064503, the entire contents of which
is incorporated herein by reference.
Another apparatus for preparing halogenated precursors of an alkenone is
now described.
The apparatus comprises two means, wherein the first means comprises a
circulation system with a boiler, pipes filled with Raschig rings, centrifugal
pump, tubular reactors each with a pipe. Product can be added or removed (for
analysis purposes) before and after each of these reactors. For safety reasons, a
further length of pipe with cooler and cold traps is mounted after circulation ;
wherein the second means is used as a receiver and for the thermolysis of the
organic products' precursors to the organic products, for example, from 4-chloro-
4-ethoxy-l,l,l-trifluoro-butane-2-one (CETFBO) to ETFBO and comprises
ceramic boiler with column pipes with Raschig rings and cooler with take-off.
It is understood that each equipment and apparatus described herein before
can comprise a surface consisting of glass or alloy in accordance with the
invention, and at least one such surface is present in the equipment used in the
process according to the invention.
In one embodiment, which is preferred, the liquid reaction medium for the
reaction comprises an alkenone, in particular ETFBO, as a solvent. The
alkenone is generally used in an amount of from 50 to 99 % by weight,
preferably from 60 to 99 % by weight, more preferably from 75 to 99 % by
weight of the alkenone relative to the total weight of the reaction medium.
This embodiment is particularly advantageous for starting up said reaction.
The alkenone comprises preferably additional alkenone which is provided
to the reaction from an external source, for example an earlier batch manufacture
of alkenone. In one aspect of this embodiment, said reaction is carried out by
introducing carboxylic acid halide into said alkenone containing liquid reaction
medium, in particular during start-up of the manufacturing process. The
formation of the halogenated precursor of the alkenone after introduction of a
vinyl ether into the liquid reaction medium comprising the alkenone and the
carboxylic acid halide will generally provide a liquid reaction medium
containing the halogenated precursor and the alkenone.
It is understood that this embodiment may also be applied for reaction of
the same type as reaction described above wherein the vinyl ether is not added to
a reaction medium containing carboxylic acid halide, for example, vinyl ether
may be dissolved in the alkenone containing reaction medium and carboxylic
acid halide is then added to the reaction medium containing vinyl ether and
alkenone.
In another embodiment, the liquid reaction medium for the reaction of the
carboxylic acid halide with the vinyl ether comprises a halogenated precursor of
the alkenone, in particular CETFBO. The halogenated precursor is generally
used in an amount of from 50 to 99 % by weight, preferably from 60 to 99 % by
weight, more preferably from 75 to 99 % by weight of the halogenated precursor
to the total weight of the reaction medium.
In a preferred aspect of this embodiment, the process is carried out in
continuous mode. In a continuous process, the content of the halogenated
precursor of the alkenone in the liquid reaction medium is generally kept in a
range from 50 to 99 %, preferably in a range from 60 to 99 %, more preferably in
a range from 75 to 99 % by weight of halogenated precursor relative to the total
weight of the reaction medium. This is particularly advantageous for a
continuous process operated in steady-state, for example in a continuously stirred
tank reactor (CSTR).
In a preferred aspect, the remainder of the liquid reaction medium
comprises carboxylic acid halide.
The liquid reaction medium generally contains at least 0.5 % by weight,
preferably at least 1% by weight of carboxylic acid halide relative to the total
weight of the reaction medium. Preferably this content is at least 5 % weight.
The liquid generally contains less than about 20 %by weight of carboxylic acid
halide relative to the total weight of the reaction medium. Preferably this content
is less than 10 % weight. Preferably, the liquid contains 5 to 10 % by weight of
carboxylic acid halide relative to the total weight of the reaction medium. This
particular aspect may also be applied to the different embodiments of the process
according to the invention described herein. The reaction can be carried out in
the presence of an additional solvent. The term "additional solvent" is
understood to denote a solvent different from the reactants, the products of said
reaction and the additional alkenone or precursor of the alkenone. The solvent to
be used may, for example, be an aromatic hydrocarbon such as benzene, toluene
or xylene, an aliphatic hydrocarbon such as pentane or hexane ; a halogenated
hydrocarbon such as methylene chloride, chloroform or ethylene dichloride or
fluorinated hydrocarbons such as 1,1,1,3,3-pentafluorobutane (commercialized
by Solvay Fluor GmbH under the trademark Solkane® 365mfc) ; or an ether such
as diethyl ether, dibutyl ether or tetrahydrofuran. Among them, an aromatic
hydrocarbon is preferred. Particularly preferred among them, is benzene or
toluene. These solvents may be used alone or in combination as a mixture. If
appropriate, the solvent is used usually in an amount of from 1 to 35 parts by
weight, preferably from 3 to 16 parts by weight, per part by weight of the
carboxylic acid halide. It is however preferred to carry out the reaction in the
substantial absence or absence of additional solvent.
In a particular embodiment, the solvent further comprises at least one
haloether, for example a chloroether such as chloroethyl-ethyl ether. In this case,
the content of haloether in the liquid reaction medium is generally from 0.1
to 5 % often from 0.5 to 2 % by weight relative to the total weight of the liquid
reaction medium. It has been found that haloethers are suitable solvents which
can be incorporated in the liquid reaction medium, in particular in the indicated
concentration ranges while achieving high productivity and selectivity to
halogenated precursor of alkenone. In a continuous process, the content of
haloether is preferably maintained in the concentration range indicated here
above.
It is more particularly preferred to carry out the reaction in a liquid reaction
medium consisting or consisting essentially of alkenone, halogenated precursor
of alkenone, carboxylic acid halide and vinyl ether. This embodiment has
particular advantages for subsequent process steps such as for example a
thermolysis or purification operations.
In the process according to the invention and in the particular embodiments
thereof, the molar ratio of acid halide to vinyl ether preferably is from 0.8 to 1.2,
and particularly preferably from 0.8:1 to about 1. Most preferably, the molar
ratio is about 1.
In the process according to the invention and in the particular embodiments
thereof, the vinyl ether is generally introduced into the liquid reaction medium at
a rate of from 0.01 to 2 mol/hour/mol of carboxylic acid halide. Preferably this
rate is from 0.5 to 1.5 mol/hour/mol of carboxylic acid halide. A rate of
about 1 mol/hour/mol of carboxylic acid halide has given good results.
The process according to the invention and the particular embodiments
thereof can be carried out batchwise or continuously.
In the process according to the invention and in the particular embodiments
thereof, it is especially beneficial, in particular in a continuous process to control
the concentration of the vinyl ether in the liquid reaction medium. Generally,
this concentration is less than 5 % by weight relative to the total weight of the
liquid reaction medium. Often the concentration of the vinyl ether in the liquid
reaction medium is equal to less than 1% by weight relative to the total weight
of the liquid reaction medium. Preferably, this concentration is equal to less
than 0.5 % by weight relative to the total weight of the liquid reaction medium.
Generally, this concentration is at least 0.1 % by weight relative to the total
weight of the liquid reaction medium.
In one embodiment of the invention, the halogenated precursor of the
alkenone which is obtained according to the process of the invention can be used
as such. For example, it can be used as solvent, e.g. as solvent in a subsequently
performed process according to the present invention.
In another embodiment of the invention, the halogenated precursor of the
alkenone which is obtained in the process according to the present invention is
dehydrohalogenated by the elimination of hydrogen halide to form the respective
alkenone. Consequently, the invention further concerns a process for preparing
an alkenone, which comprises (a) reacting a carboxylic acid halide with a vinyl
ether to form a halogenated precursor of the alkenone in a liquid reaction
medium containing an alkenone or a halogenated precursor thereof, and (b)
eliminating hydrogen halide from said precursor to form the alkenone.
In that case, the liquid reaction medium generally comprises hydrogen
halide, in particular hydrogen chloride. In the liquid reaction medium of the
manufacture of the alkenone generally a content of hydrogen halide in the
reaction medium of equal to or lower than 10 % wt is maintained. Preferably,
this content is maintained equal to or lower than 5 % wt. The content of
hydrogen halide in the reaction medium of the manufacture of the alkenone is
generally equal to or higher than 0,1 % wt albeit equal to or higher than 0,5 % wt
relative to the total weight of the reaction medium.
According to one alternative, the elimination of hydrogen halide is carried
out simultaneously during the formation of the halogenated precursor of the
alkenone, for example, in the presence of an acid scavenger and/or by thermally
inducing the elimination of hydrogen halide. The acid scavenger to be used may,
for example, be a nitrogen-containing heterocyclic compound such as pyridine,
quinoline or picoline ; or a tertiary base such as triethylamine, dimethylaniline,
diethylaniline or 4-dimethylaminopyridine. Among them, pyridine,
triethylamine, dimethylaniline, diethylaniline or 4-dimethylaminopyridine is
preferred. Among them, pyridine is particularly preferred. These acid
scavengers may be used alone or in combination as a mixture. If appropriate, the
acid scavenger is used in an amount of less than 1 equivalent, preferably less
than 0.8 equivalents per mol carboxylic acid halide.
If desired, an additional solvent may be present during the elimination of
hydrogen halide. The term "additional solvent" has the same meaning as defined
above.
In a first particular embodiment, the carboxylic acid halide is
trifluoroacetyl chloride. Preferably, the trifluoroacetyl chloride is fed in liquid
state into the reaction medium.
In a second particular embodiment, the carboxylic acid halide is
Chlorodifluoroacetyl chloride.
In a third particular embodiment, the carboxylic acid halide is
Difluoroacetyl chloride.
In a forth particular embodiment, the carboxylic acid halide is
trifluoroacetyl fluoride.
In a fifth particular embodiment, the carboxylic acid halide is
(trifluoroaceto)acetyl fluoride.
In a sixth particular embodiment, which is preferred, the process for the
preparation of a halogenated precursor of an alkenone and the elimination of
hydrogen halide is carried out in the substantial or complete absence of an acid
scavenger especially when a carboxylic acid chloride as described herein before
is used.
In a seventh particular embodiment, which is preferred, the preparation of
the halogenated precursor of the alkenone and the elimination of hydrogen halide
is carried out in the substantial or complete absence of additional solvent.
In a eighth particular embodiment, which is preferred, the preparation of
the halogenated precursor of the alkenone and the elimination of hydrogen halide
is preferably carried out in the substantial or complete absence of an acid
scavenger and of additional solvent, as described here before. The sixth to
eighth, in particular the eighth particular embodiment can be advantageously
combined with any of the first to fifth particular embodiment.
In the sixth to eighth particular embodiments of the process according to
the invention, "Substantial absence" typically denotes an optional content of
equal to or less than 1% by weight, more particularly equal to or less than 0.5 %
by weight of acid scavenger and/or solvent relative to the total weight of the
reaction medium. "Complete absence" in this context typically denotes a process
wherein no voluntary addition of acid scavenger and/or solvent to the reaction
medium has been carried out. Typically "complete absence" means that no acid
scavenger and/or solvent can be detected in a GC of the reaction medium.
In particular the sixth to eighth particular embodiments of the process
according to the invention allow for particularly efficient isolation of, if desired,
the halogenated precursor of the alkenone and in particular the desired alkenone
as reaction proceeds selectively and separation is facilitated by the limitation
albeit substantial absence of components different from the starting material and
the products of the reaction.
The invention also concerns a process for the manufacture of an alkenone,
comprising (a) the manufacture of a precursor of the alkenone according to the
process according to the process described above and (b) at least partially
converting the precursor obtained in step (a) into the alkenone, preferably by
thermolysis. In the process for the manufacture of an alkenone according to the
invention, step (b) is carried preferably out in an equipment comprising a surface
consisting of glass, polytetrafluoroethylene or alloy, as described herein before.
More specifically, the invention concerns also a process for preparing an
alkenone, which comprises (a) reacting a carboxylic acid halide with a vinyl
ether to form a halogenated precursor of the alkenone in a liquid reaction
medium containing an alkenone or a halogenated precursor thereof, and (b)
eliminating hydrogen halide from said precursor to form the alkenone.
This embodiment of the process according to the invention and the
particular embodiments thereof, generally comprises carrying out the reaction of
step (a) at a first temperature and carrying out step (b) at a second temperature
higher than the first temperature.
The first temperature is generally less than 50°C, often less than 40°C,
preferably equal to or less than 30°C. In one aspect, the temperature is
preferably equal to or less than about -25°C. The first temperature is generally at
least -50°C, often equal to or greater than -40°C, preferably equal to or greater
than -30°C.
The second temperature is generally at least 50°C, often equal to or greater
than 60°C, preferably equal to or greater than 70°C. The second temperature is
generally less than 150°C, often less than 100°C, preferably equal to or less than
about 80°C.
The process according to the invention and the particular embodiments
thereof, generally comprises carrying out the reaction of step (a) at a first
pressure and carrying out step (b) at a second pressure lower than the first
pressure.
The first pressure is generally chosen to maintain the reaction medium in
the liquid state. For example, if trifluoroacetyl chloride is used as acid halide,
the first pressure is advantageously atmospheric pressure at a reaction
temperature of equal to or less than about -25°C. The first pressure is
advantageously a pressure equal to or greater than about 4, preferably about
5 bar abs to equal to or less than about 10 bar at a reaction temperature of
from 20 to 30°C.
The second pressure is preferably chosen to allow for fractional distillation
at least of the alkenone from the reaction medium. A typical second pressure is
from 1 to about 10 bar abs.
The invention also concerns a method for storing or transporting a
precursor of an alkenone or an alkenone wherein said storing or transporting is
carried out in an equipment comprising a surface consisting of glass,
polytetrafluoroethylene or alloy, as described herein before.
The invention also concerns a process for manufacture of an organic
compound comprising use of an alkenone or precursor thereof as synthesis
intermediate, comprising the process for the manufacture of a precursor of an
alkenone or the process for the manufacture of an alkenone according to the
invention. Examples of organic compounds which can be produced using the
process according to the invention include in particular Sulfoxafluor®
or Pyroxolam®, wherein the alkenone produced according to the process
according to the invention or the precursor thereof can be suitably further reacted
according to the procedures described in WO-A-2005/063780, WO2009006217
and WO2010002577.
Should the disclosure of any patents, patent applications, and publications
which are incorporated herein by reference conflict with the description of the
present application to the extent that it may render a term unclear, the present
description shall take precedence.
The examples here after are intended to illustrate the invention without
however limiting it.
Abbreviations :
ETFBO - 4-ethoxy-l,l,l-trifluorobut-3-en-2-one
CETFBO - 4-chloro-4-ethoxy-l,l,l-trifluorobutan-2-one
Example 1
The materials indicated in the table were contacted with Hastelloy® C4
pieces, having each a weight of between 24,5 g and 24,8 g, at about 20°C
for 6 months. The weight loss was determined.
Example 2
CETFBO containing reaction medium is heated to 100°C in Hastelloy® C4.
ETFBO is obtained while the internal surface of the reactor shows no corrosion.
C L A I M S
1. A process for preparing a halogenated precursor of an alkenone, which
comprises reacting a trifluoroacetyl halide with a vinyl ether in a liquid reaction
medium using an equipment having at least one surface in contact with the liquid
reaction medium, wherein said surface consists of a material selected from an
nickel based alloy containing at least 14 % wt. molybdenum relative to the total
weight of the alloy and at least 14 % wt. of chromium relative to the total weight
of the alloy.
2. The process according to claim 1, wherein the alloy contains at
least 50 wt % nickel.
3. The process according to claim 2, wherein the alloy contains nickel, in
an amount of 50 to 7 1 wt %, relative to the total weight of the alloy, chromium,
in an amount from 14 to 20 wt %, relative to the total weight of the alloy, and
molybdenum, in an amount from 14 to 20 wt %, relative to the total weight of
the alloy, the remainder of the alloy consisting essentially of other metals.
4. The process according to any one of claims 1 to 3, wherein the alloy is
selected from Hastelloy® C alloys, preferably Hastelloy® C4.
5. The process according to any one of claims 1 to 4, wherein the
equipment is selected from the group consisting of a vessel, a tank, a tube, a
distillation column, a stirrer, a microreactor or combinations thereof.
6. Process according to anyone of claims 1 to 5, wherein the equipment
has the surface coated or lined onto a support material.
7. Process according to anyone of claims 1 to 5, wherein the equipment
consists of massive alloy.
8. Process according to anyone of claims 1 to 7, wherein the liquid
reaction medium comprises hydrogen chloride and optionally an alkenone.
9. Process according to anyone of claims 1 to 8, wherein the liquid
reaction medium has a temperature from 0°C to 120°C.
10. Process according to anyone of claims 1 to 9, wherein the
trifluoroacetyl halide is trifluoroacetyl chloride and the vinyl ether is selected
from methyl-vinyl ether and, preferably, ethyl-vinyl ether.
11. Process according to anyone of claims 1 to 10, wherein the liquid
reaction medium contains from 1%, preferably from 5 % to less than about 20 %
by weight of carboxylic acid halide.
12. Process for the manufacture of an alkenone, comprising (a) the
manufacture of a precursor of the alkenone according to the process according to
anyone of claims 1 to 11 and (b) at least partially converting the precursor
obtained in step (a) into the alkenone, preferably by thermolysis.
13. Process according to claim 12, wherein step (b) is carried out in an
equipment in accordance with anyone of claims 1 to 7.
14. A method for storing or transporting a precursor of an alkenone or an
alkenone in accordance with anyone of claims 1 to 13, wherein said storing or
transporting is carried out in an equipment in accordance with anyone of
claims 1 to 7.
15. A process for manufacture of an organic compound comprising use of
an alkenone or a precursor thereof as synthesis intermediate, comprising the
process according to anyone of claim 1 to 13 or the method according to
claim 14.