U.S. patent application number 14/719912 was filed with the patent office on 2015-09-10 for method for isolation of catmint oil.
The applicant listed for this patent is E. I. DU PONT DE NEMOURS AND COMPANY. Invention is credited to DAVID L. HALLAHAN, MARK A. SCIALDONE.
Application Number | 20150252286 14/719912 |
Document ID | / |
Family ID | 43992366 |
Filed Date | 2015-09-10 |
United States Patent
Application |
20150252286 |
Kind Code |
A1 |
SCIALDONE; MARK A. ; et
al. |
September 10, 2015 |
METHOD FOR ISOLATION OF CATMINT OIL
Abstract
A high yielding method is described for improved isolation of
catmint oil after recovery from catmint plants of the genus Nepeta.
Catmint oil can be obtained in quantitative yields for use in
insect repellent compositions.
Inventors: |
SCIALDONE; MARK A.; (WEST
GROVE, PA) ; HALLAHAN; DAVID L.; (WILMINGTON,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
E. I. DU PONT DE NEMOURS AND COMPANY |
WILMINGTON |
DE |
US |
|
|
Family ID: |
43992366 |
Appl. No.: |
14/719912 |
Filed: |
May 22, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13509061 |
May 10, 2012 |
9085747 |
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PCT/US2010/056167 |
Nov 10, 2010 |
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14719912 |
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61260370 |
Nov 11, 2009 |
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Current U.S.
Class: |
549/283 ; 554/20;
554/21 |
Current CPC
Class: |
C11C 3/126 20130101;
C11B 1/10 20130101; A01N 43/16 20130101; C07D 311/94 20130101 |
International
Class: |
C11B 1/10 20060101
C11B001/10; C07D 311/94 20060101 C07D311/94; A01N 43/16 20060101
A01N043/16; C11C 3/12 20060101 C11C003/12 |
Claims
1. A method for recovering catmint oil from plants of the genus
Nepeta, comprising (a) providing a first liquid mixture comprising
catmint oil and water; (b) contacting the first liquid mixture with
at least one water-immiscible organic extracting solvent to form a
second liquid mixture that contains a solvent phase and an aqueous
phase; (c) in the second liquid mixture, separating the solvent
phase from the aqueous phase, and recovering the solvent phase; and
(d) removing the extracting solvent from the solvent phase to
isolate the catmint oil.
2. A method for recovering catmint oil from plants of the genus
Nepeta, comprising (a) providing a first liquid mixture comprising
catmint oil and water; (b) in the first liquid mixture, separating
catmint oil from water, and recovering the catmint oil; (c)
contacting the catmint oil recovered in (b) with at least one
water-immiscible extracting solvent to form a second liquid mixture
that contains a solvent phase and an aqueous phase; (d) in the
second liquid mixture, separating the solvent phase from the
aqueous phase, and recovering the solvent phase; and (e) removing
the extracting solvent from the solvent phase to isolate the
catmint oil.
3. A method according to claim 1 or 2 wherein an aqueous phase from
which a catmint oil phase has been separated is contacted with at
least one water-immiscible extracting solvent, and a catmint oil
and extracting solvent phase is separated, the extracting solvent
removed, and the catmint oil recovered.
4. A method according to claim 1 or 2 wherein the yield of catmint
oil is at least about 50% greater than the yield of catmint oil
obtained from the separation of catmint oil from water in the
absence of an organic extracting solvent.
5. A method according to claim 1 or 2 wherein the water immiscible
organic extracting solvent has a density that is different from the
density of water by at least about 0.1 Wm.
6. A method according to claim 5 wherein the water immiscible
organic extracting solvent is selected from the group consisting of
a hexane, petroleum ether, toluene, a xylene, ethyl acetate,
dichloromethane (DCM), chloroform and mixtures thereof.
7. A method according to claim 1 or 2 further comprising
hydrogenating the recovered catmint oil.
8. A method according to claim 7 further comprising formulating the
hydrogenated catmint oil in an insect repellent composition.
Description
[0001] This application claims priority under 35 U.S.C.
.sctn.119(e) from, and claims the benefit of, U.S. application Ser.
No. 13/509,061, filed May 10, 2012, and U.S. Provisional
Application No. 61/260,370, filed Nov. 11, 2010.
TECHNICAL FIELD
[0002] This invention provides methods for improved recovery of
catmint oil from plants of the genus Nepeta (catmint).
BACKGROUND
[0003] It has been demonstrated that dihydronepetalactone exhibits
insect repellency (see, for example, US 2005/0112166, which is by
this reference incorporated in its entirety as a part for all
purposes). Dihydronepetalactone can be obtained by hydrogenation of
nepetalactone, which may be isolated as a component of the
essential oil of plants of the genus Nepeta (catmint plant).
Essential oil from Nepeta plant material, herein referred to as
catmint oil, has been obtained by various isolation processes,
including steam distillation, organic solvent extraction,
microwave-assisted organic solvent extraction, supercritical fluid
extraction, mechanical extraction and enfleurage (initial cold
extraction into fats followed by organic solvent extraction). Steam
distillation [such as described by Regnier, F. E. et al,
Phytochemistry (1967) 6:1281-1289] is the most viable method for
obtaining catmint oil. Disclosed in a commonly owned and co-pending
application published as US 2010/0034906 (which is by this
reference incorporated in its entirety as a part for all purposes)
are improved processes for steam distilling plant material from
Nepeta cataria to obtain catmint oil.
[0004] For commercial production of the insect repellent
dihydronepetalactone as derived from catmint oil, it is desirable
to have further increased yields of catmint oil containing
nepetalactone obtained from Nepeta plant material. A need thus
remains for improved techniques for the recovery of catmint oil
from Nepeta plants.
SUMMARY
[0005] The invention provides methods for recovering catmint oil
that increase the yield of catmint oil following steam extraction
of catmint oil plants which are of the genus Nepeta.
[0006] In one embodiment, this invention provides a method for
recovering catmint oil from plants of the genus Nepeta by (a)
providing a first liquid mixture comprising catmint oil and water;
(b) contacting the first liquid mixture with at least one non-water
miscible organic extracting solvent to form a second liquid mixture
that contains a solvent phase and an aqueous phase; (c) in the
second liquid mixture, separating the solvent phase from the
aqueous phase, and recovering the solvent phase; and (d) removing
the extracting solvent from the solvent phase to isolate the
catmint oil.
[0007] In another embodiment, this invention provides a method for
recovering catmint oil from plants of the genus Nepeta by (a)
providing a first liquid mixture comprising catmint oil and water;
(b) in the first liquid mixture, separating catmint oil from water,
and recovering the catmint oil; (c) contacting the catmint oil
recovered in (b) with at least one non-water miscible extracting
solvent to form a second liquid mixture that contains a solvent
phase and an aqueous phase; (d) in the second liquid mixture,
separating the solvent phase from the aqueous phase, and recovering
the solvent phase; and (e) removing the extracting solvent from the
solvent phase to isolate the catmint oil.
[0008] In yet another embodiment, the combination of the catmint
oil obtained in steps (b) and (e) is the total isolated catmint
oil.
DETAILED DESCRIPTION
[0009] This invention relates to improved methods for the recovery
of catmint oil from plant material of the genus Nepeta. Catmint oil
contains nepetalactone, and nepetalactone when hydrogenated yields
dihydronepetalactone, which has been found to serve as an insect
repellent active. The term "insect repellent" or "insect repellent
composition", as used herein, refers to a compound or composition
that deters insects from their preferred hosts or from articles of
manufacture. Typically, an insect repellent is a compound or
composition that can be either topically applied to a host, or
incorporated into an article to deter insects from the space in
which the host or article exists.
The term "invention" as used herein is a non-limiting term, and is
not intended to refer to any single embodiment of the various
inventions to the exclusion of others, but encompasses all possible
embodiments as described in the specification and the claims.
[0010] Where a range of numerical values is recited or established
herein, the range includes the endpoints thereof and all the
individual integers and fractions within the range, and also
includes each of the narrower ranges therein formed by all the
various possible combinations of those endpoints and internal
integers and fractions to form subgroups of the larger group of
values within the stated range to the same extent as if each of
those narrower ranges was explicitly recited. Where a range of
numerical values is stated herein as being greater than a stated
value, the range is nevertheless finite and is bounded on its upper
end by a value that is operable within the context of the invention
as described herein. Where a range of numerical values is stated
herein as being less than a stated value, the range is nevertheless
bounded on its lower end by a non-zero value.
[0011] In this specification, unless explicitly stated otherwise or
indicated to the contrary by the context of usage, where an
embodiment of the subject matter is stated or described as
comprising, including, containing, having, being composed of or
being constituted by or of certain features or elements, one or
more features or elements in addition to those explicitly stated or
described may be present in the embodiment. An alternative
embodiment of the subject matter, however, may be stated or
described as consisting essentially of certain features or
elements, in which embodiment features or elements that would
materially alter the principle of operation or the distinguishing
characteristics of the embodiment are not present therein. A
further alternative embodiment of the subject matter may be stated
or described as consisting of certain features or elements, in
which embodiment, or in insubstantial variations thereof, only the
features or elements specifically stated or described are
present.
[0012] In this specification, unless explicitly stated otherwise or
indicated to the contrary by the context of usage, amounts, sizes,
ranges, formulations, parameters, and other quantities and
characteristics recited herein, particularly when modified by the
term "about", may but need not be exact, and may also be
approximate and/or larger or smaller (as desired) than stated,
reflecting tolerances, conversion factors, rounding off,
measurement error and the like, as well as the inclusion within a
stated value of those values outside it that have, within the
context of this invention, functional and/or operable equivalence
to the stated value.
Improved Catmint Oil Extraction
[0013] Catmint oil exhibits several characteristics that lead to
low recovery of the oil from plant material using standard steam
distillation techniques commonly employed for the isolation of
essential oils from plant material. Catmint oil has a similar
density to water, and does not readily coalesce to form a separate
oil phase from the condensed water used in the steam distillation
process. Additionally, nepetalactone, the principal constituent of
catmint oil, hydrates at high temperatures to non-volatile and
unwanted side products. This invention overcomes these
disadvantages of the isolation of catmint oil from plant material
to provide an enhanced method for recovering the oil in high yield
at moderate temperatures.
[0014] In the methods, the volatized mixture of catmint oil and
water solution resulting from steam distillation of Nepeta plant
material (herein also called catmint plant material) is contacted
with a non-water miscible organic solvent that dissolves catmint
oil. Applicants have found that by using this extracting solvent,
there is isolation of substantial amounts of catmint oil that
remain in the aqueous portion of the steam distillate when a
catmint oil phase is separated without using the extracting
solvent. Removal of the solvent under reduced pressure affords
catmint oil suitable for use in the preparation of hydrogenated
catmint oil insect repellent. The yield of catmint oil may be
improved by at least about 50%, 55%, 60%, 65%, 70%, or greater to
achieve overall quantitative yields of at least about 80%, 85%,
90%, 95%, or 99%. For example, the yield of catmint oil may, by a
factor as set forth above, be greater than the yield of catmint oil
obtained from the separation of catmint oil from water in the
absence of an organic extracting solvent. The amount of improvement
in recovery will vary depending on factors including the level of
recovery from steam distillation alone in a particular process, the
organic solvent used for further extraction, and use of repetitions
of an extraction process.
Steam Distillation
[0015] In the methods, catmint oil plants are subjected to steam
distillation with improved extraction following condensation of the
resulting volatized mixture of catmint oil and water. Any plants of
the genus Nepeta that contain nepetalactone in the catmint oil may
be used. Preferred are plants of Nepeta cataria. Any method for
steam distillation of plant material that is known in the art may
be used such as that typically used for catmint oil recovery.
[0016] For example, according to conventional distillation
processes for recovering catmint oil, plant material from Nepeta
cataria is contacted with steam to form a vapor phase heterogeneous
mixture comprising predominantly catmint oil and water. This
volatized mixture is then condensed to form a heterogeneous liquid
mixture comprising catmint oil and water.
[0017] Diagrams of typical distillation apparatuses are shown in
commonly owned and co-pending application WO 2008/079261, which is
by this reference incorporated in its entirety as a part for all
purposes. A traditional steam distillation apparatus may be used
according to the following description. Plant material is packed
into a retort over a set of steam injectors. A suitable retort that
may be used for such purpose is available from Juniper Mfg.
(Redmond, Oreg.). The lid of the retort is closed and sealed to
both the retort and to a condenser. Steam is injected through the
injection manifold (or steam injector) and into the packed plant
material. The steam provides two functions: 1) energy to disrupt
the glandular (or secretory) trichomes on the plant and release the
oil, and 2) formation of a heteroazeotrope with the oil which
volatizes it sufficiently as to allow it to be transported into the
vapor phase. The steam and volatized oil are condensed as a mixture
distillate.
[0018] Cooling water, from any suitable water source, flows through
the condenser. Its cooling effect allows the steam and catmint oil
vapor to condense. The condenser is configured in such a way as to
allow gravity to drain the condensed water and catmint oil out of
the condenser and into a collection can. The water and catmint oil
are ducted into the collection can optionally using internal
baffles in such a way as to produce a quiescent zone to allow the
oil and water to effectively separate. The quiescent zone is the
zone where the superficial velocity of the condensate is less than
the disengagement velocity of the oil from the water. Typically,
the temperature of the condensate is controlled at a modest
temperature, approximately 40-60.degree. C., to allow the oil and
water to effectively separate in the quiescent zone of the
separation can.
[0019] In known steam distillation processes for recovery of
catmint oil, the separated catmint oil and water form two phases
with the catmint oil being the heavier, lower layer. The water is
generally removed as wastewater, for example by decantation.
[0020] In addition, the steam distillation may be carried out in a
distillation apparatus as described below. Plant material is packed
into a retort. The lid of the retort is closed and sealed to both
the retort and to a condenser. Steam for the distillation of the
catmint plant material can be provided by any suitable means such
as by direct injection through an injection manifold. In an
alternative embodiment, the steam can be obtained by adding water
to the retort, and boiling the water in the presence of the plant
material. The latter method is referred to as using a direct fired
retort. The steam and volatized catmint oil are condensed, the
catmint oil separated and collected as described above.
[0021] In one example of a steam extraction process, 13 kg of dried
catmint plant material is packed into the retort above the steam
injector so that the retort is full, and the plant material is
sealed securely to the sides of the retort so that channeling of
the steam along the inside walls of the retort is minimized. The
retort is sealed and made leak tight. Live steam produced in a
separate boiler is injected into the bottom of the retort at a rate
of 480 g/min for a total of 60 minutes. The pressure of the steam
is slightly above atmospheric pressure to allow for pressure drop
across the plant material and the condenser. The cooling water flow
is adjusted to the condenser so that the condensate temperature is
between about 45.degree. C. and about 55.degree. C. during the
distillation. It is desired to keep the temperature below about
75.degree. C., and preferably below about 60.degree. C. or about
55.degree. C. to reduce the tendency for the hydration of
nepetalactone to occur. Rate of hydration to nepetalic acid, an
undesirable by-product, increases with increasing temperature. The
temperature can be reduced by operating the distillation apparatus
under vacuum.
[0022] The amount of vacuum applied to the system will depend on
the system components, however achieving an absolute pressure of
about 13 kPa to about 70 kPa is preferred. An absolute pressure of
about 20 kPa to about 45 kPa is more preferred. In addition, the
application of vacuum can be used in systems where water is
recycled from the collection can back to the retort.
[0023] After the collection can is filled with condensate, the
water phase condensate is drawn from the collection can into a
wastewater drain, or the water is recycled.
The still is operated in this fashion for 1 hour. A total of
approximately 2.2 kg of steam is used per kg of dried catmint plant
material. Approximately 50 mL or 52 grams of catmint oil is
collected in the bottom of the collection can. This corresponds to
approximately 0.40 wt % of the original dry weight of the catmint
plant.
Enhanced Catmint Oil Recovery
[0024] In the methods, recovery of catmint oil from the
volatized-then-condensed mixture of catmint oil and water solution,
obtained in a process as described above, is improved by enhancing
separation of a catmint oil-containing phase (solvent phase) and
the aqueous phase of the distillate mixture. At least one
extraction solvent that is a non-water miscible organic solvent
that dissolves catmint oil remaining with the aqueous phase is
added to the condensed mixture of catmint oil and water solution.
Extraction solvents that may be used are any organic solvents that
are non-water miscible, that dissolve catmint oil in an aqueous
mixture, and that provide increased disengagement of catmint oil
from the aqueous portion of the mixture. Such extraction solvents
will have a density that differs from water density in a greater
amount than does the catmint oil density. Typically the density of
the extraction solvent differs from that of water by at least about
0.1 g/cc. The difference may be either positive or negative.
[0025] Extraction solvents that may be used include without
limitation hexanes, petroleum ether, toluene, xylenes, ethyl
acetate, methyl acetate, dichloromethane (DCM) and chloroform. Due
to the larger differences in densities and hydrophobicities of
these solvents with respect to an aqueous solution, as compared to
the density and hydrophobicity of catmint oil, the dissolved
catmint oil in these solvents will more easily partition from the
water in the condensed steam distillate into a separate layer that
can then be isolated from the aqueous layer.
[0026] Typically a single extraction solvent is used, although
multiple solvents may be used as mixtures or sequentially.
Typically the extraction solvent is added to the condensed steam
distillate and the combination mixed then allowed to separate.
Mixing may be by any method such as by injection, stirring or
shaking. Separation may be by any method such as settling or
floating. Separation characteristics will depend on the specific
extraction solvent used. For example, when using hexane as the
extraction solvent, the separated hexane and catmint oil will float
on the aqueous portion of the mixture. When using dichloromethane
(DCM) as the extraction solvent, the separated DCM and catmint oil
will, by contrast, settle below the aqueous portion of the mixture.
Removal of the solvent under reduced pressure affords catmint oil
suitable for use in the preparation of hydrogenated catmint oil
insect repellent.
[0027] The placement of a line that directs water from the
collection can to the retort will depend on the position of the
water in the collection can, i.e. whether the water phase is on top
of the catmint oil or below the catmint oil. Conventional
collecting equipment may be used when the extraction solvent and
catmint oil phase separates on top of the aqueous solution. In
addition, corrosion products that may be formed in the condenser or
collection can collect at the bottom of the collection can,
contaminating the liquid phase that is at the bottom of the can.
Therefore, an additional advantage to having the oil phase as the
top phase is that it is separated from any corrosion products that
may be present.
[0028] The extraction solvent and aqueous mixture may be collected
into a collection can optionally using internal baffles in such a
way as to produce a quiescent zone to allow the extraction solvent
containing catmint oil phase and aqueous phase to effectively
separate as described above for the original separation of catmint
oil and aqueous mixture.
[0029] The extraction solvent containing catmint oil is isolated
and the extraction solvent is removed by any suitable method known
in the art such as by evaporation. The extracting solvent may be
recovered and recycled.
[0030] In an alternative embodiment, extracting solvent is added to
the aqueous phase following separation of a catmint oil phase from
aqueous phase from the condensed steam extraction mixture with no
extracting solvent added. In this embodiment a portion of catmint
oil is isolated without using an extracting solvent, and an
additional portion of catmint oil is recovered using an extracting
solvent.
[0031] In another embodiment extraction with the extracting solvent
is performed multiple times by addition to the initial condensed
steam extraction mixture, and/or to the initial separated aqueous
phase, and to subsequent separated aqueous phases. Extractions may
be performed until at least about 50%, 55%, 60%, 65%, 70%, 75%,
80%, 85%, 90%, 95%, or 99% of catmint oil in the condensed steam
distillate from catmint oil plant material is recovered.
Application of Catmint Oil
[0032] Recovered catmint oil may be used to prepare an insect
repellent composition. The catmint oil is hydrogenated to convert
the nepetalactone into dihydronepetalactone, which is an effective
insect repellent. Nepetalactone, which naturally occurs in
different stereoisomers in catmint oil, is hydrogenated to form
mixtures of dihydronepetalactone stereoisomers, or
dihydronepetalactones. One example of hydrogenation to produce
dihydronepetalactones using catalysts such as palladium, or carbon
and palladium, supported on strontium carbonate is described in
Regnier et al [Phytochemistry 6:1281-1289 (1967)].
[0033] For example, the hydrogenation reaction may be carried out
in the presence of hydrogen at a temperature of about -10.degree.
C. to about 200.degree. C. The hydrogen pressure for the reaction
is generally from about 0.1 MPa to about 20.7 MPa. The time,
temperature, hydrogen pressure and flow rate and feed may be
adjusted, according to known principles, to obtain optimal
conversion of hydrogenation of catmint oil using a given catalyst.
A suitable hydrogenation reaction is that which is described in
U.S. Pat. No. 7,067,677 (which is by this reference incorporated in
its entirety as a part for all purposes). Described therein is the
hydrogenation of nepetalactone in the presence of a catalytic metal
that is not nickel, platinum or palladium. The process can be
carried out at a temperature of about 25.degree. C. to about
250.degree. C. at a hydrogen pressure of about 0.1 MPa to about 20
MPa. Other suitable processes for making a dihydronepetalactone
include a process as described in the commonly owned and co-pending
application published in U.S. 2010/0168447, which is by this
reference incorporated in its entirety as a part for all purposes.
A hydrogenation reaction may be carried out in batch in a single
reactor, in sequential batch in a series of reactors, in reaction
zones within one or more reactors, or in continuous mode in any of
the equipment customarily employed for continuous processes.
[0034] Hydrogenated catmint oil is incorporated into formulations
suitable for application to the skin, hair, fur, feathers or hide
of a human or domesticated animal. In addition, insect repellent
formulations may be applied to, or incorporated into articles.
Insect repellent formulations are designed to provide a minimum
effective evaporation rate from the skin surface or insect
repellent article to maintain the necessary minimum concentration
of repellent in the air space directly above the skin
surface/article for effective insect repellency. Disclosed in
commonly owned and co-pending applications published, respectively,
as US 2005/112166 and US 2007/0264297 (each of which is by this
reference incorporated in its entirety as a part for all purposes)
are effective carriers and insect repellent compositions prepared
using catmint oil.
[0035] Insect repellent compositions containing
dihydronepetalactones are effective against a variety of insects
which interfere with human society including a variety of biting
insects (ants, bees, black flies, chiggers, fleas, mosquitoes,
stable flies, ticks, wasps), wood-boring insects (termites),
noxious insects (house flies, cockroaches, lice, wood lice), and
household pests (flour and bean beetles, dust mites, moths,
silver-fish, weevils).
EXAMPLES
[0036] The operation and effects of certain embodiments of the
inventions may be more fully appreciated from a series of examples
(Examples 1-2), as described below. The embodiments on which these
examples are based are representative only, and the selection of
those embodiments to illustrate the invention does not indicate
that materials, components, reactants, conditions, steps or
techniques not described in the examples are not suitable for use
herein, or that subject matter not described in the examples is
excluded from the scope of the appended claims and equivalents
thereof.
[0037] The following abbreviations are used: .degree. C. is degrees
Centigrade; Kg is kilogram; g is gram; min is minute; ml is
milliliter(s); CMO is catmint oil.
Example 1
Extraction of Catmint Oil from
CMO/Water Mixture with Dichloromethane
[0038] Catmint oil (purchased from Thacker brothers, 1.73 g) was
added to a separatory funnel followed by addition of 100 g of
water. The mixture (approximately 1.73% weight/weight) was stirred,
and the catmint oil (CMO) layer, which is slightly heavier than
water, was allowed to settle. The CMO layer was then separated from
the water layer in a separatory funnel and weighed. This recovered
CMO was called the first amount of CMO.
[0039] Droplets of CMO remaining in the water layer were visible
indicating that the CMO did not fully separate from the water. A
volume of 20 ml dichloromethane (DCM), a solvent heavier than
water, was then added to the separatory funnel containing rest of
the CMO/water mixture. The funnel was shaken. Droplets of CMO
disappeared when DCM was added, and the CMO/water mixture was
shaken indicating that the CMO partitioned into the DCM fraction.
The DCM, including partitioned CMO, was allowed to settle and then
was isolated from the separatory funnel. A total of three
extractions were performed using 20 ml DCM each time, and the three
CMO/DCM mixtures were combined. The combined CMO/DCM mixtures were
dried over sodium sulfate, and DCM was removed under reduced
pressure on a rotary evaporator. The resulting sample, which was
the second amount of CMO, was weighed. Together the first and
second amounts of CMO gave the total CMO yield. Total percent CMO
yield was calculated by dividing the total weight of CMO recovered
in grams as a fraction of starting CMO amount (1.73 g). Results are
given in Table 1 below.
Example 2
Extraction of Catmint Oil from
CMO/Water Mixture with Hexane
[0040] Catmint oil (purchased from Thacker brothers, 1.56 g) was
added to a separating funnel followed by addition of 150 g of
water. The mixture (approximately 1.04% weight/weight) was stirred,
and the catmint oil (CMO) layer, which is slightly heavier than
water, was allowed to settle. The CMO layer was then separated from
the water layer and weighed. This recovered CMO was called the
first amount of CMO.
[0041] Droplets of CMO remaining in the water layer were visible
indicating that the CMO did not fully separate from the water. A
volume of 20 ml hexane (HXN), a solvent lighter than water, was
then added to the separatory funnel containing the rest of the
CMO/water mixture. The funnel was shaken. Droplets of CMO
disappeared when HXN was added, and the CMO/water mixture was
shaken indicating that the CMO partitioned into the HXN fraction.
The HXN, including partitioned CMO, was allowed to float and then
was isolated from the separatory funnel. A total of three
extractions were performed using 20 ml HXN each time, and the three
CMO/HXN mixtures were combined. The combined CMO/HXN mixtures were
dried over sodium sulfate, and HXN was removed under reduced
pressure on a rotary evaporator. The resulting sample, which was
the second amount of CMO, was weighed. Together the first and
second amounts of CMO gave the total CMO yield. Total percent CMO
yield was calculated by dividing the total weight of CMO recovered
in grams as a fraction of starting CMO amount (1.56 g). Results are
given in Table 1.
TABLE-US-00001 TABLE 1 Recovery of CMO from water. Start- First
Second Start- ing amount % amount Total Total ing CMO of CMO of CMO
% CMO Water Sol- % in CMO re- CMO yield CMO (g) (g) vent water (g)
covered (g) (g) yield 1.73 100 DCM 1.73% 0.45 26.01% 1.27 1.72
99.42% 1.56 150 HXN 1.04% 0.34 21.79% 0.97 1.31 83.97%
[0042] In other embodiments, the methods could be conducted as
described below. Steam distillation of catmint oil is carried out
in a distillation apparatus consisting of a retort, steam
generator, condenser and receiver to capture the condensate. Dried
catmint plant material is packed into the retort of the
distillation apparatus so that the retort is full. The retort is
sealed, and steam is injected into the bottom of the retort. The
pressure of the steam is slightly above atmospheric pressure, and
the cooling water temperature in the condenser of the distillation
apparatus is adjusted so that the condensate temperature in the
receiver is between 45.degree. C. and 55.degree. C. during the
distillation.
[0043] After the distillation is complete, the collected condensate
in the receiver mixture consisting of catmint oil and water is
transferred to a separatory funnel. A water immiscible extraction
solvent, such as hexane, is added and the mixture is shaken in
order to thoroughly mix the water and solvent layers. The mixture
is allowed to stand in order for the layers to completely separate
into two distinct liquid phases. The water layer is separated from
the extraction solvent layer. The extraction solvent is evaporated
from the solvent layer for recovery of the catmint oil.
[0044] Thus, catmint oil can be isolated after recovery from plants
of the genus Nepeta by a method comprising: [0045] (a) providing a
first liquid mixture comprising catmint oil and water; [0046] (b)
contacting the first liquid mixture with at least one non-water
miscible organic extracting solvent to form a second liquid
mixture; [0047] (c) separating from an aqueous phase in the second
liquid mixture a solvent phase that comprises catmint oil and the
extracting solvent; and [0048] (d) removing the extracting solvent
from the solvent phase to isolate catmint oil.
[0049] Alternatively, catmint oil can be isolated after recovery
from plants of the genus Nepeta by a method comprising: [0050] (a)
providing a first liquid mixture comprising catmint oil and water;
[0051] (b) separating catmint oil from an aqueous phase in the
first liquid mixture; [0052] (c) contacting the aqueous phase with
at least one non-water miscible extracting solvent to form a second
liquid mixture; [0053] (d) separating from an aqueous phase in the
second liquid mixture a solvent phase that comprises catmint oil
and the extracting solvent; and [0054] (e) removing the extracting
solvent from the solvent phase to isolate catmint oil.
* * * * *