Plant protecting and regulating compositions – Plant growth regulating compositions – Organic active compound containing
Reexamination Certificate
2002-10-01
2004-07-13
Clardy, S. Mark (Department: 1616)
Plant protecting and regulating compositions
Plant growth regulating compositions
Organic active compound containing
C504S359000
Reexamination Certificate
active
06762153
ABSTRACT:
The present invention relates to complexes formed from molecular encapsulation agents such as cyclodextrin, and cyclopropene and its derivatives such as methylcyclopropene, which are capable of inhibiting the ethylene response in plants. Such complexes provide a convenient means for storing and transporting these compounds which are reactive gases and highly unstable because of oxidation and other potential reactions. Such complexes also provide convenient methods of delivering to plants these compounds in order to extend their shelf life.
It is well known that ethylene can cause the premature death of plants including flowers, leaves, fruits and vegetables through binding with certain receptors in the plant. It can also promote 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 &agr;-cyclodextrin being the most preferred. The application or delivery of these active compounds is then accomplished by simply adding water to the molecular encapsulation agent complex. The complex prepared according to the methods disclosed in U.S. Pat. No. 6,017,849 provides the material in the form of a powder.
The powdered complex, although stable in the dry state, releases the 1-methylcyclopropene when added to water. Release is very quick, typically taking between five and 30 minutes, and complete for small quantities, such as milligrams, of powder. However, 1-methylcyclopropene release from larger quantities of powder can be very slow and incomplete, sometimes taking days. This is especially true for the large quantity of powdered complex needed to treat full-scale fruit storage rooms. Stirring the powder/water mixture does not appreciably speed up 1-methylcyclopropene release when large quantities of the complex are involved.
We have surprisingly found that formulating the 1-methylcyclopropene/&agr;-cyclodextrin powder with carbon dioxide-generating additives such as citric acid and sodium bicarbonate, for example, causes release of 1-methylcyclopropene more efficiently even for large quantities of powder when the powder is contacted with an aqueous solvent. It is very surprising that, even though most of the carbon dioxide itself bubbles off in the first few minutes after water is added to the formulation, actual release of 1-methylcyclopropene occurs slowly in the beginning with the majority of the release 10-60 minutes after addition of water. Continued release occurs as much as 120 minutes after addition of water. Another feature of the formulation is that due to the presence of carbon dioxide hazards associated with the highly flammable 1-methylcyclopropene are reduced.
Effervescent compositions are known. For example, International Patent Application No. WO 98-EP4517 discloses tablets containing. 20 mg piroxicam in as a piroxicam-&bgr;-cyclodextrin complex (2:5), sodium glycine carbonate, fumaric acid, PEG 600, spray-dried lactose, lemon flavor, and aspartame. The effervescent tablet allowed higher plasma concentrations 15 minutes after the administration as compared to a standard formulation, as well as a higher drug exposure during the first hours after the administration. However, piroxicam is a high-melting solid; significantly different in properties than the gaseous cyclopropenes of this invention.
Even though this formulation improves 1-methylcyclopropene release dramatically, there is often a need to have the majority of the 1-methylcyclopropene released in less than 120 minutes. This will ensure that the target crop is treated evenly and completely. We have further discovered that the addition of a water soluble substance which itself can complex with the &agr;-cyclodextrin (a “displacing substance”) improves 1-methylcyclopropene release even more. Thus, for example, the combination of the 1-methylcyclopropene/&agr;-cyclodextrin complex with citric acid, sodium bicarbonate, and benzoic acid provides very efficient release of 1-methylcyclopropene.
The present invention is, therefore, a composition comprising:
a) a cyclopropene of the formula:
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;
b) a molecular encapsulation agent within which the cyclopropene is encapsulated; and
c) one or more carbon dioxide generating additives; and
d) optionally, a displacing substance.
As used herein, the term “alkyl” means both straight and branched chain (C
1
-C
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
3
-C
20
)alkenyl and (C
3
-C
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
1
-C
15
) alkyl group substituted with a (C
3
-C
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.
Preferably, R is (C
1
-C
10
) alkyl. More preferably, R is (C
1
-C
8
) alkyl. Even more preferably R is (C
1
-C
4
) alkyl. Most preferably, R is methyl.
Preferred encapsulating agents include cyclodextrins, crown ethers, polyoxyalkylenes, polysiloxanes, and zeolites. More preferred encapsulating agents include &agr;-cyclodextrin, &bgr;-cyclodextrin, and &ggr;-cyclodextrin. The most preferred encapsulating agent, particularly when the cyclopropene is 1-methylcyclopropene, is &agr;-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.
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.
The cyclopropenes applicable to this invention are 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.
It is often desirable to include in the composition of this invention one or more adjuvants, such as, for example, binders, lubricants, release agents, surfactants and/or dispersants, wetting agents, spreading agen
Jacobson Richard Martin
Kostansek Edward Charles
Stevens Bridget Marie
Weisel Leah Anne
Clardy S. Mark
Rogerson Thomas D.
Rohm And Haas Company
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