IL29201A - Plant growth regulant compositions and method using phosphonic acid derivatives - Google Patents

Description

PLANT GROWTH REGULANT COMPOSITIONS AND METHOD USING PHOSPHONIC ACID DERIVATIVES T»n o'nas ¾m»A mo'n ΠΟ»Β?Ι a-ia^-a-w 29201 / 3 This invention pertains to novel compositions for the control of plant growth, comprising as an essential active ingredient certain phosphonic acids and phosphonic acid derivatives, which compositions cause cessation of growth of a wide variety of plant species without causing immediate death of the plants; and to the method of controlling and arresting the growth of plants without necessarily killing the plants. Certain of these phosphonic acids and phosphonic acid derivatives which are effective in the control of plant growth by the mechanism of arresting said growth are new compounds.

It is known that a variety of organophosphorus compounds exhibit herbicidal activity of varying types. However, the unusual plant responses of inhibition and arrestation of growth, caused by the phosphonic acids and acid de rivatives described herein, have not previously been reported or suggested in the prior art.

The active compounds of this invention are members of the class having the general formula: wherein (Qg 3 represents a saturated or unsaturated straight-chain hydrocarbon group having two or three carbon atoms, such as ethyl, vinyl, propyl, 1 -propenyl, allyl, 1 -propynyl, 2 -propynyl, Z represents hydroxy or acetoxy, and n = 1 or 2. Y represents a halogen atom, preferably chlorine or bromine, or -XH or the anion -X , Y' represents either any of the groups represented by Y, or -XR where R is a hydrocarbon radical. Thus, R may be a or alkenyl, fe/aftfipM44 /cfif fakkkiMife/dl straight- or branched-chain alkyl/ aryl, - la- aralkyl, or cycloalkyl group of one to about twelve carbon atoms ,· for example, R may be methyl, ethyl, propyl, allyl, isopropyl, methallyl, butyl, sec-butyl, isobutyl, pentyl, neopentyl, crotyl, 2-ethylhexyl, phenyl, benzyl, cyclohexyl. In the general formula and in the above description, X represents oxygen or sulfur.

Y and Y1 may be taken together to represent an oxygen or sulfur atom which is doubly bonded to phosphorus. When Y is the anion X , the nature of the cation is not critical, so long as it is agriculturally acceptable.

A particularly preferred group of compounds is represented , by the formula: wherein n is the integer 2 or 3, and R represents a lower alkyl radical.

A number of procedures are known for the synthesis of compounds of this class of phosphonic acids and acid derivatives. For example, O, O-dialkyl phosphonates, the preparation of which is extens ively described in the literature, may be subjected to partial hydrolysis with sodium hydroxide to give the monosodium salt of the corresponding phsphonate monoester which on acidification yields the corresponding monoacidic monoester RP(0)(OH)(OR' ).

Dialkyl phosphonates may be hydrolyzed under acid conditions such as with concentrated hydrochloric acid to give the corresponding diacidic compound RP( 0)(0H)2. Treatment of dialkyl phosphonates with phosphorus pentachloride gives the corresponding phosphonic dichloride, which on reaction with one equivalent of the appropriate alcohol in the presence of an acid acceptor gives the ester chloride R-P(O) (OR 1 ) ( CI ) . Sulfur analogs are readily correspondingly prepared, by procedures known or apparent to those skilled in this art .

The following examples illustrate certain aspects of the invention. It is to be understood that the examples are presented for purposes of illustrating selected and representative aspects of the invention, and are in no sense limitative of the scope of the invention. In the examples all temperatures are in degrees Centigrade, and all parts are by weight unless otherwise stated.

Example 1 . Preparation of 0-Ethyl Hydrogen Fropylphosphonate a. Preparation of 0, 0-diethyl propylphosphonate : To a mixture of 3^ .1 g of a 51.7$ dispersion of sodium hydride in mineral oil and 200 ml anhydrous diethyl ether was added slowly a solution of 100 g of diethyl hydrogen phosphite in 200 ml ether, the rate of addition being such as to maintain reflux. Stirring was continued until evolution of hydrogen ceased. A solution of 89.3 g of 1-bromopropane was then added, and the mixture was heated under reflux overnight. Excess sodium hydride was decomposed by adding a few drops of ethanol and the mixture was washed with water. The washed ether solution was dried, filtered and the ether re-moved by flash distillation. Distillation of the residue gave 4.5.1 g of 0,0-diethyl propylphosphonate, b.p. 88-91°/lO mm. b. Preparation of O-ethyl hydrogen propylphosphonate : A mixture of 37.1 g of 0,0-diethyl propylphosphonate and 150 ml of 10 aqueous sodium hydroxide was heated at 100° for two hours. The solution was cooled in an ice bath, acidified to about pH 4 and the acidic solution was extracted with chloroform. The chloroform extracts were dried ever anhydrous sodium sulfate. The solvent was removed by flash distillation and the residue was distilled to give 10.3 g of 0-ethyl hydrogen propylphosphonate, b.p. 106-8°/0.45 mm.

Analysis: Calc'd for C5H13O3P: C. 39.48 ,; H. 8.64 ; P. 20.32; Pound: c. 38. 4; H. 8.73; P. 19.96.

Example 2. Preparation of 0-Propyl Hydrogen Propylphosphonate To a solution of 20 g of propylphosphonic dichloride (Kabachnik and Godovikov, Doklady Akad. Nauk S.S.S.R. 110, 217 [1956]) in 1 5 ml of diethyl ether was added slowly a solution of .5 g of n-propanol and 9.7 g of pyridine in 1 5 ml of diethyl ether. The rate of addition was such that the temperature remained in the range of 20-25° . When addition was complete, the mixture was heated under reflux for 0.5 hour, then allowed to stand at room temperature overnight. The separated pyridine hydrochloride was removed by filtration and the filtrate concentrated by evaporation of the diethyl ether under reduced pressure. To the residue was added a solution of 20 g of sodium hydroxide in 200 ml of water. This mixture was maintained at 80° until it became homogeneous, and then maintained at 80° for one hour. The homogeneous mixture was then cooled to 5° and acidified with concentrated hydrochloric acid to pH 1.

The acidic solution was extracted five times with 200 ml portions of diethyl ether. The ether extracts were combined dried over sodium sulfate and concentrated under reduced pressure. The residue was distilled under reduced pressure to give 4.7 g of O-propyl hydrogen propylphosphonate, b.p. 1ΐ8.5-ΐ20°/0.0β9 mm Hg; ng5 1.4313.

Example 3. Growth Control, of Annual Plants with O-Ethyl Hydrogen Propylphosphonate In flats containing sterile loam soil were planted, at a depth of one inch, seeds of corn (Zea mays ) and lima beans (Phaseolus lunatus ) ; at a depth of one fourth to one half inch were planted seeds of lettuce (Lactuca sativa ) , mustard (Brassica juncea) and crabgrass (Digitaria sanquinalis ) , These plant species are representative of a wide variety of annual plants and were selected on this basis. The flats were watered and the plants allowed to grow under good growing conditions for two weeks. Maintaining untreated plants for comparison, the stand of plants was sprayed with a solution of 0-ethyl hydrogen propylphosphonate in a volume of acetone-water equivalent to eighty gallons per acre, at a rate equivalent to eight pounds of the phosphonate per acre. Two weeks after treatment, the condition of the treated plants was compared with that of untreated plants which had been maintained under the same growing conditions. Results are shown in Table 1.

Table 1. Response of Annual Plants Plant Condition of Plant Lima beans Primary leaves darker green and turgid; Apical growth destroyed.

Corn Plant growth arrested, followed by slow dieback from the apex.

Lettuce Slight necrosis of leaf margins.

Mustard New growth inhibited; slight marginal necrosis produced in leaves present at time of treatment.

Crabgrass Leaves initially stunted and curled, but slowly regrew to nearly normal size.

Example 4. Growth Control of Annual Plants with 0-Prcpyl Hydrogen Propylphosphonate Following the procedure described in Example 5 " , 0-propyl hydrogen propylphosphonate was applied to lima beans, corn, lettuce, mustard, and crabgrass. The response of the plants to this treatment was very similar to their response to 0-ethyl hydrogen. ropylphosphonate : the growth of lima beans, corn and crabgrass was arrested, and the general vigor of lettuce and mustard was markedly reduced.

Example 5. Control of Woody Plants with 0-Ethyl Hydrogen Propylphosphonate A formulation was prepared by mixing 59.26 parts of 0-ethyl hydrogen propylphosphonate, 37.12 parts xylene, 2.17 parts calcium dodecylbenzenesulfonate and 1.4.5 parts of a nonylphenol ethylene oxide condensate . A spray mixture was prepared by mixing 1.49 g of this formulation with sufficient water to make a total volume of 80 ml; this is equiva-lent in coneentration to six pounds of the formulation per eighty gallons of spray. Test plants were selected such that all individual plants were of uniform size and vigor. Silver maple (Acer saccharinum) plants were 24-30 inches in height with a canopy spread of about 6 inches. Mock orange (Philadelphus virginalis ) plants were 12-15 inches in height with a canopy spread of about 6-8 inches; mock orange (Philadelphus coronarius ) plants were 8 inches in height with a canopy spread of about 6 inches. Regal privet (Ligustrum regelianum) plants were Ik inches in height with a canopy spread of 15 inches. The silver maple and mock orange (P_j_ virginalis ) plants were removed from dormancy three weeks prior to treatment; the mock orange (P. coronarius ) were removed from dormancy one week prior to treatment. Regal privet plants were trimmed to size just prior to treatment. Two plants of each test species were sprayed to run-off. The treated plants were maintained under normal growing conditions for fifteen weeks, at which time the growth-arrestant response was evaluated by comparison with untreated plants.

Table 2. Response of Woody Plants Plant Condition of Plant Silver maple Shoot extension markedly inhibited; slight chlorosis of some leaves.

Mock orange New shoots and leaves reduced in size; (P . virginalis ) axillary shoots proliferated; some leaves chlorotic.

Mock orange Shoot extension inhibited; slight (P. coronarius) chlorosis of some leaves.

Regal privet No shoot expansion; new leaves minute and chlorotic; original leaves defoliated, Example 6. Control of Woody Plants with O-Propyl Hydrogen Propylphosphonate The growth arrestant properties of O-propyl hydrogen propylphosphonate were determined, using the method described in Example 5. The response of woody plants to this treatment was very similar to their response to O-ethyl hydrogen Many other examples of active growth-controlling phosphonxc acid derivatives of the class described may be prepared, by procedures known or apparent to those skilled in this / art, and demonstrated to exhibit the useful :?erhavior illustrated / herein. Such examples include the following, as essential active ingredients: Example Sodium 0-ethyl propylphosphonate mp ^ 220°, IR / Example O-Allyl hydrogen propylphosphonate bp lj51-134°/0.125mm, -Ethyl hydrogen vinylphosphonate bp 115°/0.03mm, -Methallyl hydrogen propylphosphonate bp 132-147°/ 0.15mm, IR Example 11. -Propyl hydrogen propylphosphonothiolate nf5 I.5I76, Example 12. 0-Ethyl propylphosphonochloridate bp 43- 6 °/0.35mm, n 5 I.4369, IR Example 13. Propylphosphonic oxide IR Example 14. 1-Acetoxypropylphosphonic acid IR Example 15. Propylphosphonothioic dichloride bp 72-80°/l2mm, n^ I.53 O, IR Example l6. Ethylphosphonic dichloride bp 89-97°/50mm Example 17. 0-Ethyl hydrogen propylphosphonodithioate bp 46-5-48°/ 0.01mm, IR Example 18. Propylphosphonic dichloride bp 85~88°/l9mm, n^5 1.4617, Example 19 Propylphosphonic acid mp 7I-730 Example 20 Ethylphosphonic acid mp 55-58°, IR Example 21. Disodium propylphosphonate mp^ 250'° Example 22. 0-Methyl hydrogen propylphosphonate bp 99-IO2 °/0.025mm, n 6 I.4 24 IR Example 2k. O-Pentyl hydrogen propylphosphonate bp Ij50-1 0°/10 4mm, Example 25· O-Hexyl hydrogen propylphosphonate bp 120-150°/10 4mm, n^s I.43 , IR ample 26 0-(2-Ethylhexyl) hydrogen propylphosphonate bp Ιβ5-167 °/10~4mm, IR Example 27· 0-Isopropyl hydrogen propylphosphonate bp 93"95°/0.075™™ Example 28. 1-Hydroxypropylphosphonic acid mp 1 5-157° Example 29· O-Isobutyl hydrogen propylphosphonate bp H7-II9°/0.13mm n^5 I. I3-I5, IR Example >0. O-Dodecyl hydrogen propylphosphonate bp l40°/10 5mm Example 31. O-Propyl hydrogen ethylphosphonate bp 105°/0. lmm, ^ 1.4205, IR :.

Example 32- O-Phenyl hydrogen propylphosphonate bp 115°/10 5mm, n^7 I.498O, IR Example 35- O-Ethyl hydrogen allylphosphonate bp 101°/10~5mm, IR Example 34. 0-Ethyl hydrogen trans -1-propenylphosphonate bp 130°/0.05mm, nj 1.4 11/ IR Example 35· 0-Ethyl hydrogen propylphosphonothionate bp 77°/0. l^ m, Example 36· 0-Ethyl propylphosphonochloridothionate bp 32-32.5°/0.12 n^5 1.4888, IR Example 37. -Ethyl hydrogen 1-propynylphosphonate n^5 1. 587/ Example 38. 0-Ethyl hydrogen 2-propynylphosphonate bp 85°/10 5mm, IR (I. R. means structure confirmed by infra-red spectroscopy).

The responses of annual plants to a number of these compoun were tested, following the procedure described in Example 3· Results are recorded in Table 3· Also recorded in Table 3 are results obtain by the same test procedure on diesters of propylphosphonic acid. The esters are dimethyl (A), diethyl (B), dipropyl (C), dibutyl (D), di- Table 5 . Response of Annual Plants Compound of Lima Example Beans Corn Lettuce Mustard Crabqrass 7 R R N N R 8 R R 95 10 ■ 20 10 R R-100 R R R- 80 11 R R-100 R N R- 75 12 R R-100 N N- R- 60 R-100 R R R R-100 I2* R R N N R R R-100 N N R 17 R R- 75 R-30 R 19 R R 60 R-20 R R R N N 40 21 R R N N R 22 R R-100 N N R- 95 23 R R-100 R-10 R R- 60 24 R R-100 R-20 R R- 80 R R-100 R R-95 R 26 R- 25 R R R R 27 R R- 40 N R N 28 , R N N R N 29 R R N N N ! R R N N R 1 R R N N . R 32 R R-100 N N R- 90 * 33 R R- 20 N N N Table . Response of Annual Plants - (continued) Lima Piasters Beans Corn Lettuce Mus ard Crabgrass A N N N B N N N N C O N N N N D 100 80 20 90 60 E βθ 100 40 , 95 95 F 100 80 30 90 95 R - growth retarded N - not retarded, no substantial injury- Number only - percent killed, no retardation R-number - percent killed, plants retarded also I. R. - Structure confirmed by infra-red spectroscopy The biological test results recorded in Table J illustrate that a wide variety of acidic derivatives of phosphonic acids within the scope of the present invention show plant regulator activity. Different compounds show different degrees of selectivity. At the rate of 8 lb/acre, several of the compounds, in addition to showing plant regulator activity, selectively killed certain species particularly corn and crabgrass. For each of the compounds listed, there was at least one of the test plant species, and usually more than one, which was retarded, but not killed. In many cases where ' plants were killed, it was possible to observe that they were also retarded. At lower rates of application, such compounds continue to show plant regulator activity, but do not kill. Thus the compounds of Examples 10, 22, and 2 . each gave 100^ kill of corn at 8 lb/acre; at 1 lb/acre, it was observed that these compounds all retarded corn without killing any plants.

It has been found that the active compounds of the composition of the present invention must be acids, an immediate acid precursor such as the acid chloride or anhydride, or the anion of an acid. Where the compound is a monoester, the structure of the alcohol moiety is of little importance. In contrast, neutral and covalent diesters of corresponding phosphonic acids have been found to be without growth regulant activity. The six diesters of propylphosphonic acid for which results are recorded in Table > , for example, are without retarding effect on plant growth in every case. The dibutyl, dipentyl, and dihexyl esters show herbicidal activity, but this is not the same thing as the growth regulant activity of growth retardation which the present invention comprises For application to plants, these phosphonates are normally a variety of adjuvants and carriers normally employed for facilitating the dispersion of active ingredients for agricultural applications, recognizing the fact that the formulation and mode of application of a toxicant may affect the activity of that toxicant in a given application. Thus, the phosphonates may be formulated as emulslflable concentrates, as solutions, as wettable powders, as flowable pastes, as resinous pastes, or as any of several other known types of formulations, depending on the desired mode of application. For control of established plant growth, sprays are most commonly used. Formulations suitable for use in these applications may contain as little as 0.5$ or as much as 95 or more by weight of active ingredient.

Emulslflable concentrates are homogeneous liquids which may be quite free-flowing or highly viscous, which are dispersible in water or other dispersant and which normally also contain a liquid carrier such as xylene, heavy aromatic naphthas, isophorone and other nonvolatile organic (solutions solvents. fifofl†v/efriij are homogeneous compositions in which the active ingredient is soluble in the inert liquid carrier and the combination is soluble in the final dispersant .

Wettable powders are in the form of finely divided particles which disperse readily in water or other dispersant. The wettable powder is ultimately applied to the plant growth either as a dry powder or as an emulsion in water or other liquid. Typical carriers for wettable powders include fuller's earth, kaolin clays, silicas and other highly absorbent, readily wet inorganic diluents.

Wettable powders are normally prepared to contain about -80$ of active ingredient, depending on the absorbency of -carrier . They usually also contain a small amount!; of a wetting, dispersing, cr emulsifying agent for facili-j tating dispersion. Typical wetting, dispersing, or emulsifying agents used in agricultural formulations include, for example, the alkyl and alkylarylsulfonates and sulfates and their sodium salts; polyethylene oxides,; sulfonated oils; fatty acid esters; polyhydric alcohols; and other types of surface-active agents which, in formulations where they are used, normally comprise from 1$ to 15 by weight of the formulation.

Resinous paste formulations' are mixtures containing the active ingredient dispersed or suspended in an inert solid or semi-solid organic substance obtained as an exudate of various plant or animal matter or prepared synthetically. Typical examples of resinous organic substances employed as carriers for the active ingredient . include lanolin, asphalt, agar, and paraffin. These resinous paste formulations may contain between 0,01$ and 50$ of active ingredient. For application, these resinous1 paste formulations are applied to plants 'directly to the locus of desired application as the concentrated formulation or may first be diluted to a desired concentration of active ingredient by admixture 'with additional inert carrier substance.

Plowable paste formulations are mixtures of very finely divided active ingredients suspended in an emulsifying agent .o other surface-active agent in the case of the highly concentrated flowable paste, or are suspensions in mixtures of water or other dispersing liquid with the may contain between 10$ and 90$ of active ingredient.

Other useful formulations include dusts which are admixtures of the active ingredient with finely divided solids such as talc, attapulgite clays, kieselguhr, and other organic and inorganic solids which act as dispersants and carriers for the toxicants; these finely divided solids have an average particle size of less than 50 microns in diameter.

For application, these concentrated formulations are usually dispersed in water or other liquid carrier and applied as a spray to the plant growth to be treated. Or, in the case of solid formulations, application is carried out by dusting the toxicant formulation onto the plant growth to be controlled at a time when the normal leaf surface is in a condition such that the dust particles will adhere to the leaf surface.

Due to the outstanding effectiveness of the phos-phonic acids and derivatives described herein to arrest the growth of woody* plants without causing immediate death of the plants, these products are of particular value and utility where retardation of vegetative growth and development, without total elimination of vegetation, is desired; for example, inhibition of growth of ornamental trees or shrubs so as to provide more desirable shapes or flowering patterns, or for the treatment of brush, shrubs, and trees under power lines, along highways and railroads, and in small parks so as to reduce costs of trimming and pruning.

The compounds of this invention may be combined with other active ingredients. For example, combinations with slow-acting systemic herbicides may be used for weed and "brush control, wherein the phosphonlc acid derivative retards the growth of the plant while the herbicide is translocated throughout the plant to eventually kill it. The compounds of this invention may also be formulated and/or applied with insecticides, fungicides, nema ocides, other plant growth regulators, fertilizers, and ether agricultural chemicals. In applying these active compounds, formu lated alone or with other agricultural chemicals, an effective amount and concentration of the phosphonlc acid or acid derivative is of course employed.

Claims (16)

29201 /2

1. Plant regulator compositions comprising as an essential active ingredient an effective amount of a compound of the formula Y« wherein (C)2t3 is a straight -chain hydrocarbon group having 2 or 3 carbon atoms; X is oxygen or sulfur; n is 1 or 2; Z is -OH or -OCOCH3; Y is halogen, -XH, or -X~ ; and Y' is Y or -XR wherein R is a hydrocarbon radical, with the proviso that Y and Y* can be taken together to represent X doubly bonded to the phosphorus atom, in combination with adjuvants and carriers normally employed for the dispersion of the active ingredient

2. Compositions of claim 1 wherein X represents oxygen.

3. Compositions of claim 1 wherein Y represents -XH.

4. Compositions of claim 1 wherein Y* represents -XR* wherein R' is a lower alkyl radical.

5. Compositions of claim 4 wherein Y represents halogen. - 24 - if

6. Compositions of claim 1 wherein Y and Y* are taken together to represent X doubly bonded to the phosphorus atom.

7. Compositions of claim 1 wherein the active ingredient is a compound of the formula ? OH H(CH -P v 2 n X OR wherein n is an integer; of 2 to 3 inclusive and R is a lower t alkyl radical. /

8. Method of controlling and arresting the growth i of plants which comprises applying to plants an effective amount of a compound of the formula wherein (0)313 is a straight -chain hydrocarbon group having 2 or 3 carbon atoms; ' X is ogygen or sulfur; n is 1 or 2; Z is -OH or -OCOCH3; Y is halogen, -XH, or -x"; and Y» is Y or -XR wherein R is a hydrocarbon radical, with the proviso that Y and Yr can be taken together to represent X double bonded to the phosphorus atom.

9. Method of claim 8 wherein X represents oxygen. - 15- 6. Compositions of claim 1 wherein Y and Y* are taken i together to represent X doubly bonded to the phosphorus atom, 7. Compositions of claim 1 wherein the active ingre- dient is a compound of the formula ° OH 11 / 2 n OR

10. Method of claim 8 wherein Y represents -XH.

11. Method of claim 8 wherein Y' represents - R^ wherein R' is a lower alkyl radical.

12. Method of claim 11, wherein Y represents halogen,

13. Method of claim 8 wherein Y and Y' are taken together to represent X doubly bonded to the phosphorus atom.

14. Method of claim 8 wherein the compound used is a compound of the formula wherein n is an integer of 2 to 3 inclusive, and R is a lower alkyl radical.

15. Compositions for the control of plant growth COsuBittan¾]ia¾y as hereinbefore described.

16. Method of controlling and arresting the growth according to claim 8 of plants /substantially as hereinbefore described. DATED the 21st December, 1967