U.S. patent application number 09/957752 was filed with the patent office on 2002-05-23 for delivery systems for cyclopropenes requiring less water.
Invention is credited to Kostansek, Edward Charles.
Application Number | 20020061822 09/957752 |
Document ID | / |
Family ID | 22890437 |
Filed Date | 2002-05-23 |
United States Patent
Application |
20020061822 |
Kind Code |
A1 |
Kostansek, Edward Charles |
May 23, 2002 |
DELIVERY SYSTEMS FOR CYCLOPROPENES REQUIRING LESS WATER
Abstract
The present invention relates to new delivery systems for
cyclopropenes in which compositions comprising the cyclopropene and
a molecular encapsulation agent complex further comprise additional
components which provide slow release of the cyclopropene from the
molecular encapsulating agent with water, or release of the
cyclopropene from the molecular encapsulating agent with only small
amounts of water, or both. The present invention also provides
methods to release a cyclopropene from such compositions as well as
methods to deliver a cyclopropene compound to a plant to inhibit an
ethylene response in the plant.
Inventors: |
Kostansek, Edward Charles;
(Buckingham, PA) |
Correspondence
Address: |
ROHM AND HAAS COMPANY
PATENT DEPARTMENT
100 INDEPENDENCE MALL WEST
PHILADELPHIA
PA
19106-2399
US
|
Family ID: |
22890437 |
Appl. No.: |
09/957752 |
Filed: |
September 21, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60236659 |
Sep 29, 2000 |
|
|
|
Current U.S.
Class: |
504/357 ;
504/359 |
Current CPC
Class: |
A01N 3/02 20130101; A01N
27/00 20130101; A01N 27/00 20130101; A01N 25/18 20130101; A01N
25/10 20130101; A01N 25/08 20130101; A01N 27/00 20130101; A01N
2300/00 20130101 |
Class at
Publication: |
504/357 ;
504/359 |
International
Class: |
A01N 027/00; A01N
025/28 |
Claims
We claim:
1. A composition comprising: a) a molecular encapsulation agent
within which a cyclopropene of the formula: 2 wherein R is hydrogen
or a substituted or unsubstituted alkyl, alkenyl, alkynyl,
cycloalkyl, cycloalkylalkyl, phenyl, or naphthyl group; wherein the
substituents are independently halogen, alkoxy, or substituted or
unsubstituted phenoxy; is encapsulated; b) optionally one or more
adjuvants; and c) a water absorbent material.
2. The composition of claim 1, wherein R is
(C.sub.1-C.sub.8)alkyl.
3. The composition of claim 1, wherein R is methyl.
4. The composition of claim 1, wherein the molecular encapsulation
agent is a cyclodextrin or a mixture of cyclodextrins.
5. The composition of claim 1, wherein the molecular encapsulation
agent is .alpha.-cyclodextrin.
6. The composition of claim 1, wherein the water absorbent material
is: a) one or more polymers; or b) one or more deliquescent
compounds; or c) a mixture thereof.
7. The composition of claim 1, wherein the water absorbent material
is a superabsorbent polymer.
8. A article of manufacture comprising the composition of claim 1
enclosed in a water impermeable container.
9. A method to release a cyclopropene from the composition of claim
1, comprising the step of contacting the composition with
water.
10. A method to deliver a cyclopropene compound to a plant to
inhibit an ethylene response in the plant, comprising the step of
contacting the composition of claim 1 with water in the presence of
the plant.
Description
[0001] The present invention relates to new delivery systems for
cyclopropenes in which compositions comprising the cyclopropene and
a molecular encapsulation agent complex comprise additional
components which provide enhanced release of the cyclopropene from
the molecular encapsulating agent using water. Such cyclopropenes
and their derivatives, such as methylcyclopropene, are capable of
inhibiting the ethylene response in plants. The
cyclopropene/molecular encapsulating agent complexes provide a
convenient means for storing and transporting the cyclopropenes
which are reactive gases and highly unstable because of oxidation
and other potential reactions. Such complexes also provide
convenient methods of delivering these compounds to plants in order
to extend the plant's shelf life.
[0002] It is well known that ethylene can cause the premature death
of plants or plant parts including, for example, flowers, leaves,
fruits, and vegetables through binding with certain receptors in
the plant. Ethylene also promotes leaf yellowing and stunted growth
as well as premature fruit, flower, and leaf drop. Because of these
ethylene-induced problems, very active and intense research
presently concerns the investigation of ways to prevent or reduce
the deleterious effects of ethylene on plants. U.S. Pat. No.
5,518,988 discloses the use of cyclopropene and its derivatives,
including methylcyclopropene, as effective blocking agents for
ethylene binding. However, a major problem with these compounds is
that they are typically unstable gases which present explosive
hazards when compressed. As a solution to these problems, U.S. Pat.
No. 6,017,849 discloses a method of incorporating these gaseous
compounds into a molecular encapsulation agent complex in order to
stabilize their reactivity and thereby provide a convenient and
safe means of storing, transporting and applying or delivering the
active compounds to plants. For the most active cyclopropene
derivative disclosed in U.S. Pat. No. 5,518,988,
1-methylcyclopropene, the preferred molecular encapsulation agent
is a cyclodextrin, with .alpha.-cyclodextrin being the most
preferred. The application or delivery of these active compounds to
plants is accomplished by simply adding water to the molecular
encapsulation agent complex. The complex is prepared according to
the methods disclosed in U.S. Pat. No. 6,017,849 which provides the
material in the form of a powder.
[0003] The 1-methylcyclopropene/.alpha.-cyclodextrin complex noted
above releases the 1-methylcyclopropene very quickly. However, in
order to accomplish this release large amounts of water are
required, at least ten times and preferably twenty times the weight
of the 1-methylcyclopropene/.alpha.-cyclodextrin complex. It would
be advantageous to accomplish complete release of the cyclopropene
from the complex using a minimal amount of water. This would allow
a user to treat flowers, fruits, or vegetables with the
cyclopropene gas directly in shipping containers, rather than a
large treatment container, chamber, or room.
[0004] We have surprisingly found that small amounts of absorbed
water are sufficient to release 1-methylcyclopropene from the
1-methylcyclopropene/.alpha.-cyclodextrin complex. In one
embodiment of the present invention powdered complex is mixed with
a water absorbent material such as a powdered superabsorbent
polymer. Such polymers include, for example, sodium polyacrylate.
The mixture is then placed in a sachet which can be made from a
variety of materials including, as one example, filter paper. When
this sachet is dipped in water for 10 seconds and then placed in a
container, it slowly releases the 1-methylcyclopropene gas. In
another embodiment of the invention, a deliquescent compound is
mixed with the powdered complex and placed in a sachet. When this
sachet is placed in a humid environment, such as an environment
typical for the storage of flowers, fruits, and vegetables, the
1-methylcyclopropene gas again is slowly released. Although the
delivery systems of this invention provide slow release of
1-methylcyclopropene they still provide complete release. This same
process is equally applicable to other cyclopropene/molecular
encapsulation agent complexes.
[0005] The present invention is, therefore, a composition
comprising:
[0006] a) a molecular encapsulation agent within which a
cyclopropene of the formula: 1
[0007] wherein R is hydrogen or a substituted or unsubstituted
alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, phenyl, or
naphthyl group; wherein the substituents are independently halogen,
alkoxy, or substituted or unsubstituted phenoxy;
[0008] is encapsulated;
[0009] b) optionally one or more adjuvants; and
[0010] c) a water absorbent material.
[0011] As used herein, the term "alkyl" means both straight and
branched chain (C.sub.1-C.sub.20) radicals which include, for
example, methyl, ethyl, n-propyl, isopropyl, 1-ethylpropyl,
n-butyl, tert-butyl, isobutyl, 2,2-dimethylpropyl, pentyl, octyl,
and decyl. The terms "alkenyl" and "alkynyl" mean
(C.sub.3-C.sub.20)alkenyl and (C.sub.3-C.sub.20)alkynyl groups such
as, for example, 2-propenyl, 2-butenyl, 3-butenyl,
2-methyl-2-propenyl, and 2-propynyl. The term "cycloalkylalkyl"
means a (C.sub.1-C.sub.15) alkyl group substituted with a
(C.sub.3-C.sub.6) cycloalkyl group such as, for example
cyclopropylmethyl, cyclopropylethyl, cyclobutylmethyl, and
cyclopentylethyl. The term "haloalkyl" means an alkyl radical
wherein one or more of the hydrogen atoms have been replaced by a
halogen atom. The term "halogen" means fluorine, chlorine, bromine,
and iodine.
[0012] Preferably, R is (C.sub.1-C.sub.10) alkyl. More preferably,
R is (C.sub.1-C.sub.8) alkyl. Even more preferably R is
(C.sub.1-C.sub.4) alkyl. Most preferably, R is methyl.
[0013] Preferred encapsulating agents include cyclodextrins, crown
ethers, polyoxyalkylenes, polysiloxanes, and zeolites. More
preferred encapsulating agents include .alpha.-cyclodextrin,
.beta.-cyclodextrin, and .gamma.-cyclodextrin. The most preferred
encapsulating agent, particularly when the cyclopropene is
1-methylcyclopropene, is alpha-cyclodextrin. The most preferred
encapsulating agent will vary depending upon the size of the R
substituent. However, as one skilled in the art will appreciate,
any cyclodextrin or mixture of cyclodextrins, cyclodextrin polymers
as well as modified cyclodextrins can also be utilized pursuant to
the present invention. Cyclodextrins are available from Wacker
Biochem Inc., Adrian, Mich. or Cerestar USA, Hammond, Ind., as well
as other vendors.
[0014] As used herein, all percentages are percent by weight and
all parts are parts by weight, unless otherwise specified, and are
inclusive and combinable. All ratios are by weight and all ratio
ranges are inclusive and combinable. All molar ranges are inclusive
and combinable.
[0015] The cyclopropenes applicable to this invention are known
materials prepared using the processes disclosed in U.S. Pat. Nos.
5,518,988 and 6,017,849. The cyclopropene/molecular encapsulation
agent complexes of the present invention are prepared by contacting
the cyclopropene with a solution or slurry of the molecular
encapsulation agent and then isolating the complex, again using
general processes disclosed in U.S. Pat. No. 6,017,849. In the case
of 1-methylcyclopropene, the gas is bubbled through a solution of
.alpha.-cyclodextrin in water from which the complex first
precipitates and is then isolated by filtration.
[0016] It is often desirable to include in the composition one or
more adjuvants, such as extenders, binders, lubricants, surfactants
and/or dispersants, wetting agents, spreading agents, dispersing
agents, stickers, adhesives, defoamers, thickeners, emulsifying
agents and the like. Such adjuvants commonly used in the art can be
found in the John W. McCutcheon, Inc. publication Detergents and
Emulsifiers, Annual, Allured Publishing Company, Ridgewood, N.J.,
U.S.A.
[0017] A wide variety of water absorbent materials may be used in
the compositions of this invention. These include one or more
organic materials such as superabsorbent polymers, such as, for
example, sodium polyacrylate (crosslinked), polysaccharides,
acrylamide/acrylate copolymers, and carboxymethylcellulose; one or
more inorganic deliquescent compounds such as, for example, calcium
chloride, magnesium chloride, lithium chloride, zinc chloride,
magnesium nitrate, and aluminum nitrate; and combinations and
mixtures thereof.
[0018] The combinations described above can be placed in sachets of
various compositions or included in multilayer film systems. A
typical sachet resembles a tea bag in form and/or construction and
would be stored in a water impermeable container until just prior
to use. Alternatively, the composition itself may be placed in a
water impermeable container until just prior to use. Such
containers include, for example, vials, sealed foil pouches, sealed
plastic or polymer pouches, polymer microspheres, multilayer films,
and monolithic polymer structures. In another embodiment of this
invention, the water absorbent material is prepared as a gel which
is kept separated from the complex by various physical means until
release is desired. The gel and complex are then mixed to release
the cyclopropene. Physical means to keep the materials separated
include, for example, multi-chamber vials, multichamber pouches,
and multilayer thick films.
[0019] The compositions of this invention may comprise from 3
percent to 97 percent, by weight, cyclopropene/encapsulation agent
complex and 3 percent to 97 percent, by weight, water absorbent
material. Preferably, the compositions of this invention
comprise:
1 Preferably, the compositions of this invention comprise:
1-methylcyclopropene/.alpha.-cyclodextrin complex 5-95% Water
absorbent polymer 5-95% or 1-methylcyclopropene/.al-
pha.-cyclodextrin complex 3-90% Deliquescent compound 10-97% More
preferably, the compositions of this invention comprise:
1-methylcyclopropene/.alpha.-cyclodextrin complex 15-50% Water
absorbent polymer 50-85% or 1-methylcyclopropene/.alpha.-c-
yclodextrin complex 10-30% Deliquescent compound 70-90% Even more
preferably, the compositions of this invention comprise:
1-methylcyclopropene/.alpha.-cyclodextrin complex 20-30% Water
absorbent polymer 70-80% or 1-methylcyclopropene/.alpha.-c-
yclodextrin complex 10-20% Deliquescent compound 80-90% Most
preferably, the compositions of this invention comprise:
1-methylcyclopropene/.alpha.-cyclodextrin complex 25% Water
absorbent polymer 75% or 1-methylcyclopropene/.alpha.-cycl-
odextrin complex 15% Deliquescent compound 85%
[0020] These ratios will change for different cyclopropenes,
different encapsulation agents, and water absorbent material due to
differences in molecular weights, cyclopropene uptake by the
encapsulation agents, and water absorbing ability of the water
absorbent compound. One skilled in the art can easily determine the
optimum ratios for these various combinations.
[0021] Another embodiment of this invention is a method to release
a cyclopropene from the composition of this invention, comprising
the step of contacting the composition with water. Such contact
may, for example, range from dipping a sachet containing the
complex into water to exposing the complex to a humid environment
as described above.
[0022] Another embodiment of this invention is a method to deliver
a cyclopropene compound to a plant to inhibit an ethylene response
in the plant comprising the step of contacting the composition of
this invention with water in the presence of the plant.
[0023] Some embodiments of this invention are illustrated by the
following examples:
EXAMPLE 1
1-Methylcyclopropene Release by Humidity
[0024] A dry-blend mixture of 50%
1-methylcyclopropene("MCP")/.alpha.-cycl- odextrin complex powder
and 50% dextrose powder (by weight) was prepared as a control and
as a starting material for blending with various additives. Two
samples were prepared. The first involved blending 0.1 g of the
mixture with 0.5 g calcium chloride powder and placing this mixture
in a high humidity chamber, being careful not to allow the powder
blend to contact any water directly. The second involved blending
0.1 g of the mixture with 3.0 g calcium chloride powder and placing
this mixture in a high humidity chamber, again being careful not to
allow the powder blend to contact any water directly. Two
concurrent controls were run using the mixture alone. The first
control was treated in the same manner as the calcium chloride
blends described above except that 0.10 g of the dry-blend mixture
was used without the calcium chloride. The second control used 0.10
g of the dry-blend mixture directly dissolved in 2 ml of a 15%
aqueous calcium chloride solution. The 1-methylcyclopropene release
characteristics of the samples were determined by periodically
analyzing the headspace of each for 1-methylcyclopropene. The
analysis method used gas chromatography with a flame ionization
detector. Table 1 shows the resulting release profiles of the four
sample systems.
2TABLE 1 0 g CaCl.sub.2 CaCl.sub.2 soln % MCP 0.5 g CaCl.sub.2 3 g
CaCl.sub.2 % MCP Release Time Released % MCP % MCP Released (hours)
(Control) Released Released (Control) 0.5 0.7 8 1 90 1.1 1.6 21 1.5
100 2 3.6 41 2 3 5.7 53 5 4 62 9 5 7.2 69 12 7 84 22 9 88 29 24 93
51
[0025] The results clearly show that 1-MCP can be released from the
dry-blend mixture plus calcium chloride just by the water provided
by humidity. Release is slower than from the powder dissolved
directly in the liquid. However, this is often an advantage when
treating small containers. When no deliquescent salt is present,
the 1-methylcyclopropene does release, but it is very slow and
takes several days to reach the same level of release achieved by
the 0.5 g calcium chloride system in only 9 hours.
EXAMPLE 2
1-Methylcyclopropene Release by Limited Exposure to Water
[0026] A dry-blend mixture of 50%
1-methylcyclopropene/.alpha.-cyclodextri- n complex powder and 50%
dextrose powder (by weight) was prepared as a control and as a
starting material for blending with the superabsorbent polymers
ASAP.RTM. 1100 (Chemdal Corp-BASF, Portsmouth, Va.) and Sanwet.RTM.
IM-300 (Sanyo Chemical, Kyoto, Japan). Samples were prepared by
mixing 0.3 g of the dry-blend mixture with 1.0 g polymer powder and
placing the blend in a filter paper sachet. The sachet was then
dipped in water for 10 seconds and placed in a chamber which was
then sealed. The 1-methylcyclopropene release characteristics of
the delivery systems were determined by periodically analyzing the
headspace of each for 1-methylcyclopropene as in Example 1. The
dry-blend mixture alone, as a control, was placed in a sachet,
dipped in water, and analyzed in the same manner. Table 2 shows the
resulting average release profiles produced from the two
superabsorbent polymer samples and the control.
3 TABLE 2 Release ASAP .RTM. Sanwet .RTM. Control .RTM. Time % MCP
% MCP % MCP (hours) Released Released Released 0 18 5 44 0.12 57 81
0.23 71 88 0.35 79 94 0.47 85 100 0.58 85 1 85 47 2 100 67 18
93
[0027] The 1-Methylcyclopropene release profiles demonstrate that
the sachets dipped in water release the active ingredient well and
at a slower rate than the dry-blend mixture alone.
EXAMPLE 3
1-Methylcyclopropene with Slower Release by Limited Exposure to
Water
[0028] This example is a repeat of Example 2 with ASAP.RTM. 1100
superabsorbent polymer except that the dry-blend mixture was
enclosed in a polyvinylalcohol pouch before adding it to the sachet
containing the superabsorbent polymer. Table 3 shows the release
characteristics of this system. The pouch significantly delays the
wetting of the dry-blend mixture and demonstrates a delayed (24
hr.) 1-methylcyclopropene release rather than the 2 hr.
1-methylcyclopropene release profile for material in the absence of
the polyvinylalcohol pouch.
4TABLE 3 Release Time ASAP .RTM. PVA/ASAP .RTM. (hrs) (% MCP
Released) (% MCP Released) 0 18 0 0.5 79 16 1 85 22 2 100 28 16 69
24 77
* * * * *