Patent Application
20130172191
The present invention relates to inhibiting the ethylene response in plants or plant parts. Plant parts include, for example, flowers, leaves, fruits and vegetables and may remain on the parent plant or may be harvested. The ethylene response accelerates the ripening of the plant or, especially, the harvested plant part, such as a fruit or vegetable. Such accelerated ripening makes it necessary to transport such products as quickly as possible, under optimum conditions, to the final consumer before the harvested product is rendered unmarketable by becoming prematurely rotten.
It is well known that plants contain molecular receptor sites for the molecule ethylene. Ethylene affects many plant characteristics, specifically those related to plant growth, development and senescence. For the harvester of plant products, such as fruits and vegetables, ethylene causes most problems in the area of senescence. Specifically, once fruits and vegetables are harvested, ethylene will cause these products to ripen and eventually rot at an accelerated rate. Much work has been done in an effort to either eliminate or mitigate the deleterious effects of ethylene on harvested plant products.
An example of an irreversible ethylene inhibiting agent is disclosed in U.S. Pat. No. 5,100,462. This patent discloses diazocyclopentadiene as the blocking agent. However, this compound exhibits a strong odor and is very unstable. In an effort around these problems, U.S. Pat. No. 5,518,988 discloses the discovery of cyclopropene and derivatives thereof, which are used as effective blocking agents for the ethylene binding site. However, while the compounds of this patent do not suffer from the odor problems of diazocyclopentadiene they are relatively unstable gases. Therefore, the stability of these gases, as well as the explosive potential these gases pose when compressed still present problems.
Since the cyclopropenes of the '988 patent have proven to be very effective ethylene inhibitors, it remains very desirable to find a viable means to resolve their instability problem. One approach that was taken is disclosed in U.S. Pat. No. 6,017,849. This patent shows that it is possible to encapsulate the cyclopropene molecule into a cyclodextrin molecule as a carrier. This approach allows for the safe storage and transport of the cyclopropene/cyclodextrin complex, in general providing a shelf life of more than one year.
Although the foregoing encapsulation technique provides a substantially more stable ethylene inhibiting agent, problems still remain. For instance, the double bond in the cyclopropene molecule is very reactive and makes the molecule susceptible to degradation under a variety of storage and handling conditions.
Therefore, what is needed is an ethylene inhibitor that is storage stable over a long period of time, is not susceptible to self-degradation and eliminates the significant risk of explosion associated with the handling of cyclopropenes. The present invention solves these problems by utilizing certain precursors of the cyclopropene class of ethylene inhibitor molecules. These precursors have increased storage stability. In practice, the precursors are converted to their corresponding cyclopropene molecule when treatment of the target plant parts is desired.
In one aspect, the present invention provides a method of stabilizing unstable cyclopropene molecules by converting them to their more stable cyclopropane analogs. The double bond is eliminated by binding moieties to each carbon atom component of the double bond. In the formulae of the disclosure of this invention, these moieties are designated as W1 and W2. These stabilizing moieties are selected from F, Cl, Br, I, alkoxy, acyloxy, alkoxycarbonyloxy, aminocarbonyloxy, alkylaminocarbonyloxy, dialkylaminocarbonyloxy, alkylsulfonyloxy and arylsulfonyloxy groups; with the proviso that at least one of W1 and W2 is a Br or I. In one embodiment, at least one of W1 and W2 is I. In another embodiment, both of W1 and W2 are I.
In another aspect, the present invention provides a method of generating cyclopropene derivatives of structures I, II, III and IV for use as plant ethylene response inhibitors. These compounds are represented as follows:
Structures I, II, III and IV represent cyclopropene derivative compounds which are effective ethylene antagonists. These compounds can be derived from their respective cyclopropane precursor molecules V, VI, VII and VIII:
Compounds of structures V, VI, VII and VIII are reacted with a reducing agent or a nucleophile to obtain the respective gaseous compounds of structures I, II, III, and IV. In one embodiment, compounds of structures V, VI, VII and VIII are placed into a container that defines an enclosed atmosphere, and also contains one or more plant or plant part to be treated, and then reacted with a reducing agent or a nucleophile in the container. Compounds I, II, III and IV are thus released into the target enclosed atmosphere to treat the plants or plant parts to inhibit the ethylene response.
In another aspect, the present invention provides cyclopropane compounds of structures V, VI, VII and VIII wherein:
a) each R1, R2, R3, and R4 is independently a group of the formula:
-(L)n-Z
and
-(L)m-Z;
b) W1 and W2 are selected from F, Cl, Br, I, alkoxy, acyloxy, alkoxycarbonyloxy, aminocarbonyloxy, alkylaminocarbonyloxy, dialkylaminocarbonyloxy, alkylsulfonyloxy, and arylsulfonyloxy;
c) at least one of W1 and W2 is a Br or I; and
d) the total number of non-hydrogen atoms in each compound is 50 or less; its enantiomers, stereoisomers, salts, and mixtures thereof; or a composition thereof. In one embodiment, at least one of W1 and W2 is I. In another embodiment, both of W1 and W2 are I.
For the purposes of this invention, in the structural representations of the various L groups, each open bond indicates a bond to another L group, a Z group, or the cyclopropene moiety. For example, the structural representation
indicates an oxygen atom with bonds to two other atoms; it does not represent a dimethyl ether moiety.
Typical R1, R2, R3, and R4 groups include, for example: alkenyl, alkyl, alkynyl, acetylaminoalkenyl, acetylaminoalkyl, acetylaminoalkynyl, alkenoxy, alkoxy, alkynoxy, alkoxyalkoxyalkyl, alkoxyalkenyl, alkoxyalkyl, alkoxyalkynyl, alkoxycarbonylalkenyl, alkoxycarbonylalkyl, alkoxycarbonylalkynyl, alkylcarbonyl, alkylcarbonyloxyalkyl, alkyl(alkoxyimino)alkyl, carboxyalkenyl, carboxyalkyl, carboxyalkynyl, dialkylamino, haloalkoxyalkenyl, haloalkoxyalkyl, haloalkoxyalkynyl, haloalkenyl, haloalkyl, haloalkynyl, hydroxyalkenyl, hydroxyalkyl, hydroxyalkynyl, trialkylsilylalkenyl, trialkylsilylalkyl, trialkylsilylalkynyl, dialkylphosphonato, dialkylphosphato, dialkylthiophosphato, dialkylaminoalkyl, alkylsulfonylalkyl, alkylthioalkenyl, alkylthioalkyl, alkylthioalkynyl, dialkylaminosulfonyl, haloalkylthioalkenyl, haloalkylthioalkyl, haloalkylthioalkynyl, alkoxycarbonyloxy; cycloalkenyl, cycloalkyl, cycloalkynyl, acetylaminocycloalkenyl, acetylaminocycloalkyl, acetylaminocycloalkynyl, cycloalkenoxy, cycloalkoxy, cycloalkynoxy, alkoxyalkoxycycloalkyl, alkoxycycloalkenyl, alkoxycycloalkyl, alkoxycycloalkynyl, alkoxycarbonylcycloalkenyl, alkoxycarbonylcycloalkyl, alkoxycarbonylcycloalkynyl, cycloalkylcarbonyl, alkylcarbonyloxycycloalkyl, carboxycycloalkenyl, carboxycycloalkyl, carboxycycloalkynyl, dicycloalkylamino, halocycloalkoxycycloalkenyl, halocycloalkoxycycloalkyl, halocycloalkoxycycloalkynyl, halocycloalkenyl, halocycloalkyl, halocycloalkynyl, hydroxycycloalkenyl, hydroxycycloalkyl, hydroxycycloalkynyl, trialkylsilylcycloalkenyl, trialkylsilylcycloalkyl, trialkylsilylcycloalkynyl, dialkylaminocycloalkyl, alkylsulfonylcycloalkyl, cycloalkylcarbonyloxyalkyl, cycloalkylsulfonylalkyl, alkylthiocycloalkenyl, alkylthiocycloalkyl, alkylthiocycloalkynyl, dicycloalkylaminosulfonyl, haloalkylthiocycloalkenyl, haloalkylthiocycloalkyl, haloalkylthiocycloalkynyl; aryl, alkenylaryl, alkylaryl, alkynylaryl, acetylaminoaryl, aryloxy, alkoxyalkoxyaryl, alkoxyaryl, alkoxycarbonylaryl, arylcarbonyl, alkylcarbonyloxyaryl, carboxyaryl, diarylamino, haloalkoxyaryl, haloaryl, hydroxyaryl, trialkylsilylaryl, dialkylaminoaryl, alkylsulfonylaryl, arylsulfonylalkyl, alkylthioaryl, arylthioalkyl, diarylaminosulfonyl, haloalkylthioaryl; heteroaryl, alkenylheteroaryl, alkylheteroaryl, alkynylheteroaryl, acetylaminoheteroaryl, heteroaryloxy, alkoxyalkoxyheteroaryl, alkoxyheteroaryl, alkoxycarbonylheteroaryl, heteroarylcarbonyl, alkylcarbonyloxyheteroaryl, carboxyheteroaryl, diheteroarylamino, haloalkoxyheteroaryl, haloheteroaryl, hydroxyheteroaryl, trialkylsilylheteroaryl, dialkylaminoheteroaryl, alkylsulfonylheteroaryl, heteroarylsulfonylalkyl, alkylthioheteroaryl, heteroarylthioalkyl, diheteroarylaminosulfonyl, haloalkylthioheteroaryl; heterocyclyl, alkenylheteroycycyl, alkylheteroycycyl, alkynylheteroycycyl, acetylaminoheterocyclyl, heterocyclyloxy, alkoxyalkoxyheterocyclo, alkoxyheterocyclyl, alkoxycarbonylheterocyclyl, heterocyclylcarbonyl, alkylcarbonyloxyheterocyclyl, carboxyheterocyclyl, diheterocyclylamino, haloalkoxyheterocyclyl, haloheterocyclyl, hydroxyheterocyclyl, trialkylsilylheterocyclyl, dialkylaminoheterocyclyl, alkylsulfonylheterocyclyl, alkylthioheterocyclyl, heterocyclylthioalkyl, diheterocyclylaminosulfonyl, haloalkyllthioheterocyclyl; hydrogen, fluoro, chloro, bromo, iodo, cyano, nitro, nitroso, azido, chlorato, bromato, iodato, isocyanato, isocyanido, isothiocyanato, pentafluorothio; acetoxy, carboethoxy, cyanato, nitrato, nitrito, perchlorato, allenyl; butylmercapto, diethylphosphonato, dimethylphenylsilyl, isoquinolyl, mercapto, naphthyl, phenoxy, phenyl, piperidino, pyridyl, quinolyl, triethylsilyl, trimethylsilyl; and substituted analogs thereof.
Typical G groups include, for example: saturated or unsaturated cycloalkyl, bicyclic, tricyclic, polycyclic, saturated or unsaturated heterocyclic, unsubstituted or substituted phenyl, naphthyl, or heteroaryl ring systems such as, for example, cyclopropyl, cyclobutyl, cyclopent-3-en-1-yl, 3-methoxycyclohexan-1-yl, phenyl, 4-chlorophenyl, 4-fluorophenyl, 4-bromophenyl, 3-nitrophenyl, 2-methoxyphenyl, 2-methylphenyl, 3-methyphenyl, 4-methylphenyl, 4-ethylphenyl, 2-methyl-3-methoxyphenyl, 2,4-dibromophenyl, 3,5-difluorophenyl, 3,5-dimethylphenyl, 2,4,6-trichlorophenyl, 4-methoxyphenyl, naphthyl, 2-chloronaphthyl, 2,4-dimethoxyphenyl, 4-(trifluoromethyl)phenyl, 2-iodo-4-methylphenyl, pyridin-2-yl, pyridin-3-yl, pyridin-4-yl, pyrazinyl, pyrimidin-2-yl, pyrimidin-4-yl, pyrimidin-5-yl, pyridazinyl, triazol-1-yl, imidazol-1-yl, thiophen-2-yl, thiophen-3-yl, furan-2-yl, furan-3-yl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, quinolyl, isoquinolyl, tetrahydrofuryl, pyrrolidinyl, piperidinyl, tetrahydropyranyl, morpholinyl, piperazinyl, dioxolanyl, dioxanyl, indolinyl and 5-methyl-6-chromanyl, adamantyl, norbornyl, and their substituted analogs such as, for example: 3-butyl-pyridin-2-yl, 4-bromo-pyridin-2-yl, 5-carboethoxy-pyridin-2-yl, 6-methoxyethoxy-pyridin-2-yl.
Preferably, two of R1, R2, R3, and R4 are hydrogen. More preferably, R1 and R2 are hydrogen or R3 and R4 are hydrogen. Even more preferably, R2, R3, and R4 are hydrogen or R1, R2, and R3 are hydrogen. Most preferably, R2, R3, and R4 are hydrogen.
Preferably, n is from 0 to 8. Most preferably, n is from 1 to 7. Preferably, m is 0 to 4. Most preferably, m is from 0 to 2.
Preferably, D is —CXY—, —SiXY—, —CO—, or —CS—. More preferably D is —CXY—. Preferably, E is —O—, —S—, —NX—, or —SO2—. Preferably, X and Y are independently H, halo, OH, SH, —C(O)(C1-C4)alkyl-, —C(O)O(C1-C4)alkyl-, —O—(C1-C4)alkyl, —S—(C1-C4)alkyl, or substituted or unsubstituted (C1-C4)alkyl. Preferably, Z is H, halo, or G. More preferably, Z is H or G.
Preferably, each G is independently a substituted or unsubstituted; five, six, or seven membered; aryl, heteroaryl, heterocyclic, or cycloalkyl ring. More preferably, each G is independently a substituted or unsubstituted phenyl, pyridyl, cyclohexyl, cyclopentyl, cycloheptyl, pyrolyl, furyl, thiophenyl, triazolyl, pyrazolyl, 1,3-dioxolanyl, or morpholinyl. Even more preferably, G is unsubstituted or substituted phenyl, cyclopentyl, cycloheptyl, or cyclohexyl. Most preferably, G is cyclopentyl, cycloheptyl, cyclohexyl, phenyl, or substituted phenyl wherein the substituents are independently selected from 1 to 3 of methyl, methoxy, and halo.
In one aspect, the present invention provides a method that comprises converting the precursor compounds of structures V, VI, VII and VIII into the corresponding ethylene antagonistic compounds of structures I, II, III, and IV, respectively. This is achieved by reacting the compound of structures V, VI, VII or VIII with a reducing or a nucleophilic agent. The moieties identified as W1 and W2 on structures V, VI, VII and VIII are often referred to as “leaving groups”. These groups will remain on the core molecule until cleaved off by reaction with, as in this instance, a reducing or nucleophilic agent. Once the reducing or nucleophilic agent cleaves off the leaving group, the molecule of structures V, VI, VII and VIII converts to the molecule of structures I, II, III and IV, respectively.
Reducing agents may be classified as metals, organometallic reagents and low valent metal ions. Suitable examples of metals are zinc, magnesium, iron, copper, samarium and aluminum. Examples of organometallic reagents are methyllithium and n-butyllithium. Low valent metal ions include Cr(II), Ti(II), Cu(I) and Fe(II). The most preferred reducing agent is metallic zinc.
Nucleophilic agents include mercaptans, selenides, phosphines, phosphites, Na2S, Na2Te, Na2S2O4, diethylphosphite sodium salt, KSCN, NaSeCN, thiourea, diphenyltelurium and Nal. These nucleophiles may also be incorporated into polymeric reagents.
In one embodiment, a method to inhibit the ethylene response in plants includes (i) contacting a compound of structure V, VII, VII, or VIII with a reducing or nucleophilic agent to convert the compound of structure V, VI, VII, or VIII into its respective analogous compound of structure I, II, III, or IV; and (ii) contacting the plant with the compound of structure I, II, III, or IV. Because the compounds of structure V, VI, VII, and VIII are significantly more stable under storage and shipment conditions than their respective analogous compounds of structure I, II, III, and IV, it will typically be desired to delay the contacting of a compound of structure V, VII, VII, or VIII with a reducing or nucleophilic agent until shortly before treatment of a plant or a plant part is desired and/or until the compound of structure V, VII, VII, or VIII and the plant or plant part to be treated are at the same locus. Providing the compound of structure V, VII, VII, or VIII and the plant or plant part to be treated at the same locus typically includes shipment of a compound of structure V, VII, VII, or VIII from a first location at which it is manufactured to a second location at which it is intended to be used. The compound of structure V, VII, VII, or VIII may also be shipped through various channels of trade, possibly including extended periods of storage. In another embodiment, a method to inhibit the ethylene response in plants includes (i) providing a precursor compound of structure V, VI, VII, or VIII; (ii) storing the precursor compound until a time when treatment of a target plant or plant part is desired; (iii) contacting the precursor compound with a reducing or nucleophilic agent to convert the precursor compound into its respective analogous compound of structure I, II, III, or IV; and (iv) contacting the plant or plant part with the compound of structure I, II, III, or IV. In yet another embodiment, a method to inhibit the ethylene response in a plant or a plant part includes (i) providing at a locus a plant or a plant part to be treated and a precursor compound of structure V, VI, VII, or VIII; (ii) contacting the precursor compound with a reducing or nucleophilic agent to convert the precursor compound into its respective analogous compound of structure I, II, III, or IV; and (iii) contacting the plant or plant part with the compound of structure I, II, III, or IV. The locus can be, for example, a warehouse where a plant or plant part to be treated is being stored or other container that defines a target enclosed atmosphere in which a plant or plant part is located. In these embodiments, the R groups, W groups and (L)p groups of structures I, II, III, IV, V, VI, VII, and VIII are as described herein.
Molecules of structure V are preferred in the practice of this invention. The most preferred molecule is where R1=CH3, R2=H, R3=H, R4=H, W1=I and W2=I. This molecule is identified as 1,2-diiodo-1-methylcyclopropane. In the practice of this invention, this molecule represents a stable precursor to the ethylene antagonist 1-methylcylopropene. The following reaction shows the conversion from the stable 1,2-diiodo-1-methylcyclopropane to the gaseous 1-methylcylopropene upon reaction with zinc.
A number of examples were prepared. Different leaving groups are also exemplified. Although 77 examples were actually prepared, it is only necessary to show a few reaction schemes. The number of the example correlates with the same number in the list of structures identified.
Into a 3000 ml three necked round bottomed flask equipped with a mechanical stirrer was added 350 g of bromoform, 575 g of methylene chloride, 130 g of vinyl bromide, 4.5 g of N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide and 60 g of 45% aqueous potassium hydroxide. After stirring for two days, 500 ml of water was added and the organic layer was separated. An additional 4.5 g of N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide and 60 g of 45% aqueous potassium hydroxide were added and stirring was resumed overnight. After washing with water, the organic layer was distilled yielding 1,1,2-tribromocyclopropane bp (10 torr) 75-80° C. nmr (CDCl3) δ 1.72 (t, 1H), 2.76 (t, 1H), 3.58 (t, 1H).
A solution of 9.42 ml (0.0728 mol) of 2,3-dibromopropene in 70 ml diethylether was placed under a nitrogen atmosphere by use of a Firestone valve. While cooling in an ice water bath, a solution of 0.091 mol of pentylmagnesium bromide in 70 ml diethyl ether was added slowly via addition funnel. After stirring for 2 hours while warming to room temperature, there was then added via syringe 50 ml of 1 N hydrochloric acid to the reaction cooling in an ice water bath. The resulting mixture was transferred to a separatory funnel and the phases were separated. The organic layer was dried over MgSO4 and filtered. The solvent was removed from the filtrate in vacuo to yield 15.0 g (85.7% of theory) of 81% pure 2-bromo-oct-1-ene as an oil.
To 5.42 g (28.4 mmol) of 2-bromo-oct-1-ene in 7.42 ml (85.1 mmol) of bromoform and 48.8 ml of methylene chloride, were added 1.30 g (2.84 mmol) of N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide and 12.1 ml (142 mmol) of 45% aqueous potassium hydroxide. The mixture was stirred at room temperature for 5 days. There was then added hexanes and water. This mixture was filtered. The resulting mixture was transferred to a separatory funnel and the phases were separated. The organic layer was dried over MgSO4 and filtered. The solvent was removed from the filtrate in vacuo to yield 5.25 g (51.0% of theoretical) of 1,1,2-tribromo-2-hexyl-cyclopropane as an oil.
To 20 g of methyl alcohol was added 1.33 g (16.2 mmole) of anhydrous sodium acetate and 3.3 g (13 mmole) of elemental iodine. The mixture was cooled to 5° C. whereon 2.0 g of 1-octylcyclopropene (13 mmole) [prepared from 1,2,2-tribromo-1-octylcyclopropane by the method of Baird, Mark S.; Hussain, Helmi H.; Nethercott, William; J. Chem. Soc. Perkin Trans. 1, 1986, 1845-1854] The reaction was stirred at room temperature for two hours. The reaction was concentrated in vacuo and the product was diluted with hexanes and washed with dilute aqueous sodium hydroxide. Re-concentration in vacuo and column chromatography over silica gel gave 1.7 g of the desired 1,2-diiodo-1-octylcyclopropane. nmr (CDCl3) δ 0.88 (m, 4H), 1.3 (m, 10H), 1.5-1.8 (m, 5H), 3.26 (t, 1H).
1-benzylcyclopropene [prepared from 3.65 g (10.0 mmole) of 1,2,2-tribromo-1-benzylcyclopropane by the method of Baird, Mark S.; Hussain, Helmi H.; Nethercott, William; J. Chem. Soc. Perkin Trans. 1, 1986, 1845-1854] was added to a stirred mixture of 0.77 g (9.4 mmole) of anhydrous sodium acetate and 2.60 g of elemental iodine in 30 g of methanol. After stirring overnight, the reaction was concentrated in vacuo and the product was diluted with hexanes and washed with dilute aqueous sodium hydroxide. Re-concentration in vacuo and column chromatography over silica gel gave 3.0 g of the desired 1,2-diiodo-1-benzylcyclopropane. nmr (CDCl3) δ 1.18 (t, 1H), 3.1 (abq, 2H), 3.41 (t, 1H), 7.3 (m, 5H).
To 300 g of methyl alcohol was added 8.2 g (100 mmole) of anhydrous sodium acetate and 53 g (209 mmole) of elemental iodine. The mixture was cooled to 5° C. whereon 19 g of 1-methylcyclopropene [prepared from 3-chloro-2-methyl-propene; see, for example, Hopf, H.; Wachholz, G.; Walsh, R. Chem. Ber., 118, 3579 (1985), and Köster, Ret al., Liebigs Annalen Chem., 1219-1235, (1973).] was added. The reaction was stirred at room temperature until the color lightened. The reaction was concentrated in vacuo and the product was diluted with hexanes and washed with dilute aqueous sodium hydroxide. Re-concentration in vacuo gave 45.7 g of the desired 1,2-diiodo-1-methylcyclopropane. Bp (5 torr) 76° C. nmr (CDCl3) δ 0.88 (t, 1H), 1.71 (t, 1H), 1.99 (s, 3H), 3.22 (t, 1H).
Into a 3000 ml three necked round bottomed flask equipped with a mechanical stirrer was added 500 g of chloroform, 103 g of vinyl bromide, 5.6 g of N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dibromide and 200 g of 45% aqueous potassium hydroxide. After stirring for two days, 500 ml of water was added and the organic layer was separated. The organic layer was distilled yielding 1,1-dichloro-2-bromocyclopropane by (760 torr) 140-150° C. nmr (CDCl3) δ 1.65 (t, 1H), 2.13 (t, 1H), 3.53 (t, 1H).
Cyclopropane, made from 10 ml of allyl chloride by the method of Binger [J. Org. Chem. 61, 6462-6464 (1996)] was condensed into a flask containing 10.13 g of iodine, 2 g of pyridine and 100 g of 2-propanol at −70° C. The reaction mixture was slowly warmed to +10° C. over the course of three hours and concentrated in vacuo. The resulting mixture was partitioned between diethyl ether and dilute aqueous hydrochloric acid. Washing the ether layer with dilute aqueous sodium hydroxide, saturated aqueous sodium chloride, drying over anhydrous magnesium sulfate, and concentration in vacuo yielded 6.0 g of trans-1,2-diiodocyclopropane which was purified by column chromatography over silica gel. nmr (CDCl3) δ 1.36 (t, 2H), 2.66 (t, 2H).
Structural examples of compounds produced according to the invention.
Chemically Induced Release of a cyclopropene
Control Experiment
Into a 50 ml Florence flask with magnetic stirring was placed 2 ml of tetrahydrofuran and 0.30 g of 1,2-diiodo-1-methylcyclopropane. After stirring for 5 minutes GC analysis of the headspace showed no detectable 1-methylcyclopropene. GC method uses Varian CP-PoraBOND Q column 10 meters long 0.32 mm ID; helium carrier; initial temperature 50° C.; initial time 0 minutes; ramp rate 20° C./min; final temperature 270° C.; final time 5 minutes; injection volume 0.20 ml. The retention time of an authentic sample of 1-methylcyclopropene was 2.91 minutes. 1 ppm is easily detectable under these conditions.
1-methylcyclopropene Formation Using Zinc Metal in tetrahydrofuran
Into a 100 ml Florence flask with magnetic stirring was placed 2 ml of tetrahydrofuran and 1.0 g of zinc dust. The zinc was activated with 10 drops of 1,2-dibromoethane. Then 0.34 g of 1,2-diiodo-1-methylcyclopropane was added. After stirring for 20 hours, GC analysis of the headspace showed 4658 ppm 1-methylcyclopropene.
1-methylcyclopropene Formation Using Zinc Metal in Methanol
Into a 100 ml Florence flask with magnetic stirring was placed 2 ml of methanol and 1.0 g of zinc dust. The zinc was activated with 10 drops of 1,2-dibromoethane. Then 0.34 g of 1,2-diiodo-1-methylcyclopropane was added. After stirring for 30 minutes GC analysis of the headspace showed 98390 ppm 1-methylcyclopropene.
1-methylcyclopropene Formation Using Magnesium Metal
Into a 100 ml Florence flask with magnetic stirring was placed 2 ml of tetrahydrofuran and 1.1 g of magnesium turnings. The magnesium was activated with 10 drops of 1,2-dibromoethane. Then 0.35 g of 1,2-diiodo-1-methylcyclopropane was added. After stirring for 3 hours GC analysis of the headspace showed 49993 ppm 1-methylcyclopropene.
1-methylcyclopropene Formation Using triphenylphosphine
Into a 50 ml Florence flask with magnetic stirring was placed 3 g of dimethylformamide and 1.2 g of triphenylphosphine. Then 0.83 g of 1,2-diiodo-1-methylcyclopropane was added. After stirring for 15 minutes at room temperature, GC analysis of the headspace showed 10 ppm 1-methylcyclopropene.
1-methylcyclopropene Formation Using 4-methylbenzenethiol
Into a 100 ml Florence flask with magnetic stirring was placed 2 g of dimethylformamide, 0.70 g of potassium t-butoxide, and 0.84 g of 4-methylbenzenethiol. Then 0.40 g of 1,2-diiodo-1-methylcyclopropane was added. After stirring for 15 minutes at room temperature, GC analysis of the headspace showed 87567 ppm 1-methylcyclopropene.
1-methylcyclopropene Formation Using Polymer Containing benzenethiol Groups
The polymeric reagent was prepared by slurrying 50 ml of Duolite™ GT73 (Rohm and Haas Company) and stirring for two hours with 50 ml of water and 10 g of 45% aqueous potassium hydroxide. The slurry was filtered, washed twice with water, thrice with methanol, air dried, and placed in a vacuum oven overnight. 0.54 g of this polymeric reagent was placed in a 122 ml vial and the beads were wetted with 0.10 g of 1,2-diiodo-1-methylcyclopropane in 0.70 g of methanol. After standing overnight at room temperature, GC analysis of the headspace showed 134 ppm of 1-methylcyclopropene.
This is a continuation-in-part of U.S. patent application Ser. No. 12/752,280 filed Apr. 1, 2010, pending, which is a divisional of U.S. patent application Ser. No. 10/630,282 filed Jul. 30, 2003, abandoned, which claims priority to U.S. provisional patent application No. 60/401,308 filed Aug. 6, 2002, expired, each of which is incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 60401308 | Aug 2002 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10630282 | Jul 2003 | US |
| Child | 12752280 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12752280 | Apr 2010 | US |
| Child | 13776233 | US |
