Note: Descriptions are shown in the official language in which they were submitted.
CA 02311782 2000-OS-26
1
METHOD FOR EXTRACTING ORGANIC MOLECULES) USING A
SOLVENT MEDIUM CONTAINING A HYDROE'LUOROETHER
The invention relates to the field of organic
chemistry.
More precisely, the invention relates to a new
method for solubilizing one or more organic molecules
using a solvent medium containing a hydrofluoroether.
The invention finds application in particular in
extraction, purifying, fractionating, separating,
refining, depolluting, analysis operations, etc... These
operations concern chiefly, but not exclusively, the
aromatic, cosmetic, pharmaceutical, agribusiness, fine
chemistry or environment-related industries.
The use of the solubilizing properties of some
molecules is a well-known operation, in particular for
the purpose of obtaining concentrated extracts. In this
precise example, the extracts are conventionally
obtained by contacting a given raw material with an
extraction solvent such as hexane, acetone, ethanol.
This contacting may be conducted by hot or cold
maceration, with or without shaking, by single or
multiple extraction, for time intervals of varying
lengths, etc... according to a unit protocol in separate
batches or a continuous process. Other physical means
may also be applied such as ultrasound or microwaves in
CA 02311782 2000-OS-26
2
order to optimise extraction kinetics, yields or the
quality of the extracts. On completion of the
extraction, the exhausted raw material is separated from
the solvent containing the solutes. The latter are
concentrated by evaporation of the extraction solvent
until a crude extract is obtained. The crude extract may
undergo subsequent purification treatments such as, for
example, desolvation. During the evaporation stage, the
solutes undergo thermal stress which may lead to the
denaturing of some of its constituents (onset of
"roasted" notes, change in colour, loss of activity,...).
This degradation may be particularly extensive during
the final desolvation of the extract, since industrial
regulations lay down increasingly severe standards for
residual solvent(s).
To these technical and regulatory restrictions must
be added those imposed by consumers who demand products
of increasingly higher purity, devoid of any toxicity
yet having faultless organoleptic qualities.
New technologies have therefore been developed in
order to substitute in full or in part those solvents
having a certain extent of toxicity such as benzene,
hexane or chlorinated products. Among these
technologies, extraction using a gas in supercritical
state has been the subject of numerous patent
applications. By gas in the supercritical state is meant
a gas which, when placed under special conditions of
temperature and pressure, enters into an intermediate
state between a liquid and a gas. On a phase diagram,
this state is located beyond the critical point.
In known methods concerning this technique, the
solvent gas may be carbon dioxide, alkanes or alkenes
(butane, butene, propane, propene,...), chlorinated
molecules such as chlorofluorocarbons (CFCs), etc...
either separately or in a mixture. For reasons of
toxicity and safety, the solvent gas is most often
CA 02311782 2000-OS-26
3
carbon dioxide, whose critical point co-ordinates are 73
bars and 31.3°C. However, in most of the described
methods, carbon dioxide is preferably subjected to a
pressure of between 100 and 300 bars. The cost of the
installations using supercritical methods is
proportional to pressure constraints. These
installations are therefore, by definition, extremely
costly and rather more reserved up until now for
products with high added value.
To reduce installation costs, . several patent
applications describe methods based on the principle of
the refrigerating cycle in which the solvent gas of
varying chemical nature is not in the supercritical
state but simply liquefied under the action of pressure
in the range of 2 to 25 bars.
Patent application EP 0 616 821 (on behalf of Wilde
P.) describes just such a method which generally uses
non-chlorinated hydrofluoroalkanes as solvent gas and in
particular 1,1,1,2-tetrafluoroethane. In this method,
1,1,1,2-tetrafluoroethane is liquefied under the action
of a pressure of 6 bars and placed in contact with the
raw material to be extracted. However, since 1,1,1,2-
tetrafluoroethane has limited solvent power, exhaustion
of the raw material is conducted using multiple-
percolation according to the well-known Soxhlet
technique.
In order to remedy this constraint, patent GB 2 288
552 (Powell R.) describes a method based on the same
principle but which uses a hydrofluoroether as solvent
gas instead of 1,1,1,2-tetrafluoroethane.
Hydrofluoroethers combine the qualities of 1,1,1,2-
tetrafluoroethane (safety, non-flammability, chemical
inertia) with distinctly greater solvent power. However,
in the described method, the hydrofluoroethers used are
characterised by a number of carbon atoms lying between
CA 02311782 2000-OS-26
4
2 and 4 and a boiling point generally in the range of
-85°C and 15°C, preferably between -70°C and -
10°C.
These characteristics require the use of specific
equipment with which the solvent gas can be liquefied
under pressure before and during extraction. For
industrial application, this obligation becomes a non-
negligible financial restriction since the industrialist
must replace or considerably modify production tooling.
The purpose of the present invention is to put
forward a new method for solubilizing or insolubilizing
an organic molecule or a group of organic molecules in a
solvent or a mixture of solvents, which does not involve
the above-cited disadvantages of the prior art.
In particular, one objective of the present
invention is to describe said method which may be
implemented using atmospheric pressure at room
temperature.
A further objective of the present invention is to
disclose such a method which uses an atoxic solvent or
mixture of solvents.
These different objectives are reached through the
invention which concerns a method using at least one
solubilization step of an organic molecule or group of
organic molecules in a solvent medium, characterised in
that said solvent medium contains at least one
hydrofluoroether chosen from the group made up of
methoxy-nonafluorobutane (C4F90CH3) and its isomer
( ( CF3 ) 2CFCF20CH3 ) , ethoxy-nonafluorobutane ( C4FgOC2H5 ) and
its isomer ( (CF3) zCFCF20C2H5) and propoxy-
undecafluoropentane (CSF110C3H~), said hydrofluoroether
having a boiling point in atmospheric pressure ranging
between +15°C and +100°C.
The method of the invention has the major advantage
of being able to be implemented under normal conditions
of pressure and temperature, that is to say at
atmospheric or near atmospheric pressure and at room or
CA 02311782 2000-OS-26
near room temperature. Preferably, the method of the
invention is implemented at room temperature and at
atmospheric pressure.
Within the scope of the present invention, said
5 hydrofluoroethers may be used pure or in a mixture. In
addition to their high solvent power, they have the
advantage of being non-toxic, chemically inert, non
flammable, colourless, odourless, tasteless. They also
have low calorific capacity and low latent heat of
to vaporization. Finally, they also have the advantage of
having zero Ozone Depletion Potential (ODP) and a low
Global Warming Potential (GWP).
Also, preferably, said hydrofluoroether has a
boiling point at atmospheric pressure in the range of
+30°C to +80°C.
According to one variant of the invention, said
solvent medium may, in addition to at least one
hydrofluoroether, also contain at least one co-solvent.
By co-solvent is meant any molecule of any chemical
nature whatsoever added in varying quantities to the
hydrofluoroethers for the purpose of altering the
properties of the mixture obtained (solvent power,...).
According to the present invention, the preferred co
solvents have the lowest toxicity possible. By way of
example, that is in no way restrictive, ethanol and
water are considered to be co-solvents within the scope
of the present invention.
The present invention may be implemented in
particular to obtain extracts of superior quality from a
raw material, and/or to purify and/or fractionate such
extracts under normal conditions of pressure and
temperature.
When the method of the invention is used to obtain
extracts of superior quality from a raw material, the
method of obtaining these new extracts conforms to the
prior art: placing the hydrofluoroether(s), whether or
CA 02311782 2000-OS-26
6
not containing one or more co-solvents, in contact with
a determined raw material by hot or cold maceration,
with or without shaking, by single or multiple
extraction, for time intervals of varying lengths, etc...
Other physical means may also be used such as ultrasound
or microwaves in order to optimise the extraction
kinetics, yields or the quality of the extracts.
The exhausted raw material after extraction is
separated from the solvent containing the solutes. The
latter are concentrated by evaporation of the
hydrofluoroether(s) until the extract is obtained. Given
the physico-chemical characteristics of
hydrofluoroethers, it is not necessary to apply any
special pressure before or during extraction. Extraction
is therefore conducted under atmospheric pressure. This
characteristic of the invention is of importance since
it allows substitution of conventionally used extraction
solvents by hydrofluoroethers without requiring any
change to existing industrial tooling.
The extracts obtained are characterised by: no
toxicity caused by extraction solvents, low residual
solvent content, high purity and low production costs
while complying with the most restrictive environmental
standards. This last characteristic of the extracts
obtained can be accounted for by the absence of any need
for changes to production tooling and easy
hydrofluoroether regeneration.
The method of the invention may also be used to
purify and/or fractionate extracts obtained with a
conventional extraction method in order to remove, or at
least substantially reduce, the concentration of one or
more undesired molecules in the extract. By way of
example of such molecules, that is in no way
restrictive, mention may be made of the extraction
solvents used in conventional methods and pesticides.
CA 02311782 2000-OS-26
7
The hydrofluoroether(s) containing one or more
undesired molecules are separated from the extract by
simple sedimentation, filtration or azeotropic
separation.
Given the physico-chemical characteristics of the
hydrofluoroethers of the present invention, it is not
necessary to apply any special pressure either before or
during purifying and/or fractionating. It is therefore
conducted at atmospheric pressure. In addition, all the
purification and/or fractionating steps are conducted at
a temperature of below 80°C, preferably at room
temperature.
The refined extracts obtained show no or a greatly
reduced number of undesired molecules, low residual
solvent content, high purity, intactness of the "noble"
constituents of the extract (no thermal degradation),
low production costs while conforming to the most
restrictive environmental standards.
The invention also covers any extract or any
purified extract which may be obtained by using the
method of the invention. Such extracts may in particular
be aromatic extracts, active ingredients, colouring
extracts, etc...
The invention and the various advantages it offers
will be more easily understood on reading the following
description of four non-restrictive examples of
embodiment.
Example 1:
100 g of lavendula hybrida flowers crushed and
dried (dry matter - 85 %) are placed in contact with 2
litres of methoxy-nonafluorobutane (C4F90CH3). The
mixture is brought to 45°C and shaken for 5 hours. After
solid/liquid separation, the filtrate is evaporated in a
vacuum (250 mbar, 48°C). An extract weighing 13.16 grams
CA 02311782 2000-OS-26
8
is collected which has the aromatic notes characteristic
of hybrid lavender.
Example 2:
30 grams of whole dried flowers of lavendula
hybrida and 250 g of methoxy-nonafluorobutane
(C4F90CH3)are added to a mixing grinder of Warring
Blender type in order to crush the flowers directly in
contact with the solvent. After grinding for 30 seconds
at 22°C the flowers are separated from the solvent by
filtration and rinsed twice in l5 ml of fresh solvent.
The lavender residue is replaced in contact with the
same quantity of fresh solvent and re-extracted under
the same conditions. Overall, 5 successive extractions
are made. Each filtrate is evaporated separately. The
extracts obtained are weighed and the results given in
the table below.
Grinding/extractio 1 2 3 4 5
n
Mass of extract 1.72 0.67 0.58 0.58 0.13
(g)
The global yield of the 5 extraction tests is 12.27
o. The total mass of extract obtained is 3.68 g. The
first extract obtained is in the form of a limpid
slightly yellow-coloured oil. It has a strong smell and
has the aromatic notes that are characteristic of hybrid
lavender flowers.
Example 3:
An emulsion water model is reconstituted by
emulsifying 1 o by mass of essential oil of lavender
(obtained by conventional hydrodistillation) in
demineralised water. The emulsion obtained has a milky
CA 02311782 2000-OS-26
9
appearance characteristic of emulsion waters. 170 grams
of this solution are placed in contact with quantities
of methoxy-nonafluorobutane (C4F90CH3) in accordance with
a methoxy-nonafluorobutane/emulsion ratio (m/m) of 0.01,
0.02, 0.1 and 0.2 relative to the emulsion. After
homogenisation and sedimentation, the methoxy-
nonafluorobutane containing the essential oil is drawn
off and evaporated in a vacuum (250 mbars, 48°C). An
additional test is made conducting 3 successive washings
of the model in accordance with a global ratio of 0.3.
The table below gives the percentages of essential oil
extracted from the model in relation to the ratio and
expressed relative to the initial quantity of essential
oil in the model.
Ratio 0.01 0.02 0.1 0.2 0.3*
essential oil 3g 44 67 72 1 0
5 0 4 % 5 0 7 0 83
extracted , . . . .
* result obtained for 3 washings
The best result is obtained with a ratio (methoxy-
nonafluorobutane/model) of 0.3 with 3 successive
washings. In this case, 83 % of the emulsified essential
oil is extracted with methoxy-nonafluorobutane.
Example 4:
A model of food oil to undergo de-solvation is
reconstituted by incorporating 150 ppm of hexane in
commercial soybean oil. The exact content of hexane in
the oil is determined using the IUPAC 2 607 method by
head space in gaseous phase chromatography.
It is desired to solubilize the residual hexane in
the methoxy-nonafluorobutane and to collect the solution
obtained by simple sedimentation. The methoxy
nonafluorobutane is incorporated into the model
according to a (methoxy-nonafluorobutane/residual
CA 02311782 2000-OS-26
l~
hexane) ratio of 5. After homogenisation and
sedimentation for one hour at room temperature (25°C),
oil samples are taken to analyse the hexane content. The
results obtained show that 23.5 % of the hexane
initially present is extracted from the oil by methoxy-
nonafluorobutane in a single extraction.
The above-described examples of the invention are
not intended to limit the scope of the invention. In
this respect, it will be noted that the invention may be
implemented under any method requiring the
solubilization of a molecule or a group of molecules in
a solvent.
