IE46956B1

IE46956B1 - Substituted isoxazolyl benzoates and their use as herbiciddes and plant growth regulants

Info

Publication number: IE46956B1
Application number: IE960/78A
Authority: IE
Original assignee: Monsanto Co
Priority date: 1977-05-12
Filing date: 1978-05-11
Publication date: 1983-11-16
Also published as: MX5300E; PH14737A; RO84779A; DK207478A; CS197321B2; PL110437B1; RO84914A; IE780960L; BR7802953A; SU738490A3; HU181477B; IL54692A; EG13353A; NO151745C; IL54692A0; IT7823288A0; IT1094829B; RO84779B; PL206702A1; NO151745B

Abstract

Substituted isoxazolylbenzoates of the formula: are previously unknown active compounds for regulating the growth or the development of desired or unwanted plants. They can be employed pre-emergence or post-emergence in a conventional manner. In the formula, A and B have the meanings given in Claim 1.

Description

This invention relates to novel isoxazol-5-yl-benzoates and isoxazol-3-yl-benzoates as well as their use as agricultural chemicals. The novel compounds have been found to be effective in controlling the growth of undesired vegetation. At fairly low rates, the compounds have been found to be effective in regulating the growth of desirable plants.

The compounds of the invention may be represented by the following chemical formula or wherein A is «^l-n ; and B is pyridyl / (C°2R)n ; n is 0 or 1; and R is hydrogen, lower alkyl or agriculturally acceptable cations; with the proviso that B may be pyridyl only when ji is 0.

One preferred class of compounds of the present invention is the class wherein B is Another preferred class of compounds of the present invention is the class wherein the compound has a phenyl group substituted by a trifluoromethyl group in the meta position.

The isoxazol-5-yl-benzoates of the invention may be prepared by 10 reacting the appropriate hydroxamoyl chloride with an o-vinylbenzoate under basic conditions (such as in the presence of tertiary amines) to form the isoxazolin-5-yl-benzoate which can then be converted to the isoxazol-5-yl benzoate either upon heating with N-bromosuccinimide or diihlorodicyanobenzoquinonone. In order to clarify the above the following reaction scheme is presented: 469^6 ΝΗ,ΟΗ (I) Aryl-CHO —-► aqueous C2HgOH CK/CHCK or (II) Aryl-CH = NOH —-NOCI/ether (III) Aryl— C=NOH + I Cl ether H = CH, NBS or DDQ CC1„ > Aryl _C~ CH | co2r As is apparent to those skilled in the art, the appropriate hydroxamoyl chloride is prepared in accordance with the above reaction scheme by reaction of hydroxylamine with an arylaldehyde in aqueous alcohol to form Compound II which can then be chlorinated to the hydroxamoyl chloride (III).

Aryl aldehydes may be prepared by the procedure of Jolad and Rajagopal, Org. Syn., Coll., Vol. V, Page 139 (1973). The o-vinylbenzoate may be prepared by treatment of vinylbenzoic acid with thionyl chloride and then with an alcohol. cj-Vinylbenzoic acid may be prepared in accordance with the following Examples 1-3 are presented as an illustration of the above procedure.

Example 1 Preparation of o-Vinylbenzoic Acid The sodium salt of 2-carboxybenzaldehyde was prepared by addition of 129.6 g (0.60 mol) of 25% sodium methoxide in methanol to a solution of 90 g (0.6 mol) of 2-carboxybenzaldehyde in 900 ml of methanol, followed by concentration under vacuum to 90°C at 0.5 torr.

Methylenetriphenylphosphorane was prepared on a 0.605 mol scale in dimethylsulfoxide from methyl triphenylphosphonium bromide and dimsylsodium as described in E.J. Corey et al., J. Org. Chem., Vol. 28, Page 1128 (1963). Then the sodium carboxylate was added with stirring under N2- After a few minutes, the solution was concentrated under oil pump vacuum (45°C maximum bath temperature), and water was added to the residue. The mixture was filtered, and to the filtrate was added 57 ml of concentrated HCl with stirring. The resultant mixture was extracted with ether. The ether solution was extracted with 5% NaOH. The aqueous layer was acidified with HCl and then extracted with ether. The ether solution was dried and concentrated under vacuum to 61 g (69%) of sticky solid. A small portion was recrystallized from pet ether to give 1.5 g of solid, mp 89-90°C.

Example 2 Preparation of Methyl o-Vinylbenzoate A mixture of 58.5 g (0.395 mol) of o-vinylbenzoic acid and 127.3 g (1.08 mol) of thionyl chloride was heated on a steam bath (strong gas evolution) for 40 minutes until gas evolution subsided. The solution was concentrated, and 270 ml of methanol was added slowly.

The mixture was held at reflux for 10 minutes· and then was concentrated. Ether was added to the residue, and the solution was extracted three times with water. The ether layer was dried, a little hydroquinone was added, and the solution was distilled to give 32.2 g (50.5%) of liquid, B.P. 64-78°C (0.2 torr).

. Example 3 Preparation of Methyl 2-[3-[js-(Trifluoroniethy1)Phenyl]5-Isoxazolyl] Benzoate A solution of 8.67 g (0.0858 mol) of triethylamine in 25 ml of ether was added dropwise with stirring to a solution of 19.19 g (0.0858 mol) of m-trifluoromethylbenzohydroxamoyl chloride and 13.9 g (0.0858 mol) of methyl opvinylbenzoate in 200 ml of ether at 0-5°C during 45 minutes. The mixture was stirred in an ice hath for 2 hours and then at 20°C for 21 hours, and then was washed three times with water. The ether layer was filtered.to remove a little gelatinous solid, and the filtrate was dried (CaSO^) and concentrated under vacuum to 10 torr at 60°C to give 29.5 g (98%) of oil, methyl 2 - [3 -£3 - (trifluoromethyl)phenyl] - 2 - isoxazolin - 5 yl] benzoate.

A solution of 26.74 g (0.0766 mol) of the isoxazoline from above and 13.6 g (0.0766 mol) of N-bromosuccinimide in 250 ml of CCl^ was heated with stirring at reflux. A 0.5 g sample of benzoyl peroxide was added; after 10-15 minutes the red colour of Br2 was evident.

After the reaction mixture was held at reflux for 1 hour, another 0.1 g of benzoyl peroxide was added, and heating was continued for 6 9 5 6 another hour. The reaction mixture was allowed to cool and was filtered free of succinimide. The filtrate was concentrated under vacuum, and the residual oil was subjected to Kugelrohr distillation at 140-170¾ (0.2 torr); a temporary loss of vacuum to 1-2 nm occurred when the pot temperature reached 140°C, and a sour smell emitted from the oil pump, indicative of HBr evolution. The distillate was subjected to another Kugelrohr distillation to give 20.01 g of 98% pure product as a viscous oil. Crystallization of the oil from ether-hexane at 0°C gave 13.86 g of solid mp 46.5-48.5¾.

C Η N Anal. Calculated for 62.25; 3.48; 4.03 Found: 62.33 3.49; 4.09 Acids may be prepared by hydrolysis of the appropriate ester, as illustrated in Example 4. Salts may be prepared by reaction of the appropriate base with the free acid.

Example 4 Preparation of 2-j_3-(3-Trifluoromethylphenyl)-5Isoxazolyl) Benzoic Acid.

A solution of 6.20 g of methhl 2-(^3- (3 - trifluoromethyl phenyl) - 5 - isoxazolyi] benzoate, 75 ml of acetic acid, and 50 ml of concentrated HCl was held at reflux for 4 hours, cooled, and poured into 450 ml of cold water. The resultant solid was crystallized from CH3CN to give 3.87 g of solid, mp 176-177¾.

C H Anal. Calculated for CpH^FgNOj; 61.27; 3.02 Found: 61.25; 3.03 The isoxazol-3-yl-benzoates may be prepared as follows: I Cl As is apparent to those skilled in the art, o-formylbenzoates may be prepared by known techniques. Addition of hydroxylamine hydrochloride in aqueous methanol results in 2-(hydroxyiminomethyl)benzoates which can be converted to the appropriate esters of benzohydroxamoyl chloride by the addition of chlorine in chloroform. Reaction of the appropriate esters of benzohydroxamoyl chloride with an olefinic or acetylenic benzene results in either the isoxazole or crude isoxazolines that may be converted to isoxazoles by treatment with N-bromosuccinimide or dichlorodicyanobenzoquinone.

In accordance with the above procedure and by way of example thereof, the following Examples are presented.

Example 5 Preparation of o-Methoxycarbonylbenzohydroxamoyl Chloride Methyl £-formylbenzoate was prepared in 81% yield from 2-carboxybenzaldehyde by the procedure of Brown and Sargent, Journal Chemical Society, P 1818 (1969). A solution of 1.64 g (0.010 mol) of methyl o-formylbenzoate and 1.05 g (0.015 mol) of hydroxylamine hydrochloride in 95 ml of 30% aqueous methanol was stirred at 23°C for 50 minutes and then was cooled in ice. Scratching induced crystallization of 0.70 g of white solid (mp 73-74.5°C) which was methyl 2-(hydroxyiminomethyl)benzoate. Chlorine gas was slowly bubbled into a solution of 7.87 g (0.0439 mol) of methyl 2-(hydroxyiminomethyl)-benzoate in 250 ml of CHC13 stirred at 0°C (ice-methanol bath). A blue colour formed, and the clear solution became cloudy. Within a few minutes, the blue reaction mixture turned green. After about 20 minutes, excess chlorine gas began to come through the solution, so chlorine addition was stopped and the solution was stirred in an ice bath for 1 hour until the green colour had nearly all faded. Nitrogen gas was bubbled through the solution as it was allowed to warm to 20°C during 30 minutes. The solution was concentrated under aspirator vacuum at 30-40°C. The residue was triturated with 50 ml of ether, and the supernatant was decanted from a little insoluble gum and was concentrated to 7.21 9 of viscous oil. This compound was identified as o-methoxycarbonylbenzohydroxamoyl chloride.

Example 6 Preparation of Methyl 2-[5-(3-Trifluoroniethyl)Phenyl-3Isoxazolyl]Benzoate • To a solution of 12.3 g (0.0714 mol) of m-trifluoromethylstyrene and 15.6 g (0.073 mol) of o-methoxycarbonylbenzohydroxamoyl chloride in 200 ml of ether stirred at 0-5°C was added dropwise a solution of 9.43 g (0.073 mol) of ethyldi isopropyl amine in 35 ml of ether during 45 minutes. The mixture was stirred at 0-5°C for another 2 hours and then at 20°C for 3 hours. Ether, 50 ml, was added, and the mixture was extracted three times with 200 ml portions of water. The ether layer was dried (CaSO^) and concentrated under vacuum to 90°C at 0.5 torr to give T8.4 g of residual oil which was identified as methyl 2- Q> - [3 - (trifluoromethyl Jphenylj -2-isoxazolin -3-yl]- benzoate.

A mixture of 14.2 g (0.0407 mol) of methyl 2- [5 -£3 15 . (tri fluoromethyl) phenyl J -2-isoxazolin - 3 - yl]benzoate, 7.26 g (0.0408 mol) of N-bromosuccinimide, and 0.3 g of benzoyl peroxide in 150 ml of carbon tetrachloride was heated at reflux for 4 hours, cooled, filtered, and concentrated under vacuum to 14.5 g of oil. Kugelrohr distillation gave about 89% pure product at 158-160°C (0.1 torr), which was redistilled to give 9.8 g (70%) of 97% pure product at 148°C (0.1 torr).

CHN Anal. Calculated for ClgH12F3N03: 62.25; 3.48; 4.03 Found: 62.27; 3.50; 4.09 Example 7_ Preparation of Methyl 2-l5-(2-Pyri A solution of 7.38 g (0.0702 mol) of 2-vinyl pyridine and 9.07 g (0.0702 mol) of ethyl di isopropyl amine in 60 ml of ether was added dropwise during 20 minutes to a solution of 15.0 g (0.0702 mol) of o-methoxycarbonylbenzohydroxamoyl chloride in 200 ml of ether stirred at 0-5°C. The mixture was stirred at 0-5°C for another two hours and then at 20°C for 24 hours and then was washed twice with aqueous NaHC03 solution and once with aqueous NaCl solution. The ether layer was dried (CaSO^) and analyzed by ir, which revealed some nitrile oxide to be left. The ether solution was allowed to stand another 48 hours and then was concentrated to 90°C at 0.15 torr to give 14.23 g of viscous oil, methyl 2 - [5-(2- pyridyl) - 2 - isoxazolin - 3 yl] benzoate.

A mixture of 11.0 g (0.039 mol) of methyl 2 - [5 - (2 - pyridyl) 2 - isoxazolin - 3 - yljbenzoate and 9.76 g (0.043 mol) of 2,3 - dichloro - 5,6 - dicyano - 1,4 - benzoquinone in 200 ml of chlorobenzene was left at reflux for 3 hours; the mixture was allowed to cool, was filtered, and was concentrated under vacuum to 12.0 g of residue. The residue was chromatographed on 400 g of silica gel with 202 ether in benzene to give 3.8 g (352) of solid, mp 54-57°C.

Recrystallization of a small sample gave solid with mp 58-60.5°C C, Anal. Calculated for gg 55.

Found: Η, N, 4.32; 9.99 4.35; 9.93 68.41; Acids may be prepared by hydrolysis of the appropriate ester as illustrated in Example 8.

Example 8 Preparation of 2-[5-[3-(Trifluoromethyl)Phenyl]-3-Isoxazolylj8enzoic Acid A 9.8 g sample of methyl 2 - 05 - |_3 - (trifluoromethyl) phenyl J f - 3 - isoxazolyij benzoate (see Example 6) in benzene was allowed to stand on an Activity I alumina column for three days. Elution of the column with glacial acetic acid gave 15 g of solid. This solid was added to dilute HCl, and the solution was extracted with ether. Concentration of the ether gave 3.8 g of solid, which was recrystallized from aqueous Η, N, 3.02; 4.20 3.02; 4.24 methyl 2 - [δ has been prepared.

H, 4.32 4.32 As used herein, the term lower alkyl is understood to mean those alkyl groups having from 1 to 5 carbon atoms, inclusive.

The term agriculturally acceptable cations is understood to mean those cations which are commonly used in agricultural compositions to form the salt of the free acid, including but not limited to the alkali metal, substituted amine and ammonium cations. ethanol to give 3.0 g of solid acid, mp 165-167 C.

C, Anal. Calculated for C^H-]qF3NO3: Found: 61.05; In a manner analogous to that described above, (4 - pyridyl) - 3 - isoxazolyl] benzoate, mp 84-85°C, C, Anal. Calcualted for C^gH]2^2%5 gg 57 Found 68.43 As noted above, the compounds of the present invention have been found to be effective in the partial or total inhibition of undesirable vegetation. Tables I and II summarize results of tests conducted to determine the pre-emergent as well as the post-emergent herbicidal activity of the compounds.

The pre-emergent tests were conducted as follows: A good grade of top soil was placed in aluminium pans and compacted to a depth of three-eights to one-half inch from the top of the pan. On the top of the soil was placed a predetermined number of seeds or vegetative propagules of various plant species. The soil required to level fill the pans after seeding or adding vegetative propagules was weighted into a pan. A known amount of the active ingredient applied in a solvent or as a wettable powder and the soil were thoroughly mixed, and used as a cover layer for prepared pans. After treatment, the pans were moved into a greenhouse bench where they were watered from below as needed to give adequate moisture for germination and growth.

Unless noted otherwise, approximately 4 weeks after seeding and treating, the plants were observed and the results recorded. Tables I and II below summarize such results. The herbicidal rating was obtained by means of a fixed scale base on the percent injury of each plant species.

The ratings are defined as follows: % Control Rating 0-24 -49 50-74 75-100 The post-emergent tests were conducted as follows: The active ingredients are applied in spray form to two or three week old specimens of various plant species. The spray, a solution or wettable powder suspension containing the appropriate rate of active ingredient to give the desired test rate and a surfactant, is applied to the plants. The treated plants are placed in a greenhouse and unless otherwise noted approximately four weeks later the effects ranging from partial to total inhibition are observed and recorded. The results are shown in Table I in which the post-emergent herbicidal activity index is as follows: % Control Rating 0-24 0 -49 1 50-74 2 75-99 3 100 4 The plant species utilized in these tests are identified by letter in accordance with the following legend: A-Soybean I-Hemp Sesbania B-Sugarbeet J-Lambsquarters C-Wheat K-Smartweed D-Rice L-Velvet Leaf E-Sorghum M-Bromus Tectorum F-Cocklebur N-Panicum Spp. G-Hild Buchwheat Ο-Barnyard Grass Η-Morning Glory P-Crabgrass TABLE I Pre-Emergent Plant Species Compound of example WAT* kg/h A B C D E F G H I ύ K L 3 4 1.12 2 2 1 3 2 1 2 2 3 1 3 1 4 5.60 3 3 2 3 3 2 3 3 3 2 3 2 4 4 1.12 3 2 0 3 1 0 2 1 3 2 2 1 4 5.60 3 2 1 3 3 1 3 2 2 3 3 2 6 4 1.12 1 2 1 2 2 0 2 2 2 2 3 1 4 5.60 2 3 2 3 2 2 3 2 2 2 2 2 7 2 1.12 1 1 0 1 0 0 0 1 1 1 0 0 4 5.60 2 2 1 2 2 1 0 1 2 2 1 1 8 4 1.12 1 2 1 1 1 0 1 2 2 2 2 1 4 5.60 2 2 2 3 2 1 2 2 3 2 3 1 Post-Emergent Plant Species 3 2 1.12 1 0 1 0 0 1 1 1 1 1 1 1 4 5.60 1 1 0 0 0 1 1 1 0 1 1 1 M N P 2 2 2 3 3 3 1 2 2 3 0 0 0 *Weeks after treatment The compounds were also tested by utilizing the above procedure the following plant species: on A-Canada Thistle G-Nutsedge B-Cocklebur H-Quackgrass C-Velvet Leaf I-Johnson Grass D-Morning Glory J-Downy Brome E-Lambsquarters K-Barnyard Grass F-Smartweed The results are summarized by Table II. 6 9 56 TABLE II Pre-Emergent Plant Species example WAT* kg/h A B C D E F G H I J K 3 4 11.2 3 2 2 3 3 3 2 3 3 2 3 4 4 11.2 3 3 3 2 2 3 1 3 0 3 3 6 4 11.2 2 1 2 2 3 3 2 2 3 3 3 7 4 11.2 3 0 2 1 1 2 0 1 0 0 2 8 4 11.2 3 1 2 2 3 3 1 3 1 . 2 2 *Weeks after treatment TABLE II Post-Emergent Plant Species Compound of example WAT* kg/h A B C D E F G H I J K 3 4 ’ 11.2 2 2 2 2 4 4 0 7 2 2 3 4 4 11.2 1 1 1 1 2 2 1 0 1 2 2 6 4 11.2 1 1 1 1 1 1 1 1 1 1 1 7 4 11.2 0 1 1 1 1 1 Q 0 0 0 1 8 4 11.2 2 2 1 1 2 2 2 1 1 1 2 *Weeks after treatment.

The above table illustrates one aspect of the present invention. That is, the use of the compounds of the invention to kill or injure undesirable plants, e.g. weeds. Another aspect of the invention, however, is the use of said compounds for the regulation of desirable plant growth especially dicotyledonous plants such as legumes, trees and sugarbeets.

As used herein, the regulation of plant growth or development is understood to mean the modification of the normal sequential development of a treated desirable plant to agricultural maturity. Such modifications are most readily observed as changes in size, shape, colour or texture of the treated plant or any of its parts. Similarly, changes in the quantity of plant fruit or flowers are also quite apparent from visual inspection.

The above changes may be characterized as an acceleration or retardation of plant growth, stature reduction, leaf or canopy, alteration, increased branching, terminal inhibition, increased flowering, defoliation, increased root growth, increased cold hardiness and the like. While many of these modifications are desirable in and of themselves, most often it is their effect on the economic result that is of most importance. For example, a reduction in stature of the plant permits the growing of more plants per unit area. A darkening of the foliar colour may be illustrative of higher chlorophyll activity indicative of improved rate of photosynthesis.

Although the regulation of plant growth in accordance with the present invention may include partial inhibition of plant growth, it does not include the total inhibition or killing of such plants. The present invention contem20 plates the use of an amount of active ingredient which will modify the normal sequential development of the treated plant to agricultural maturity. Such plant growth regulation amounts may vary, not only with the material selected, but also with the modifying effect desired, the species of plant and its stage of development, the plant growth medium and whether a permanent or a transitory effect is sought. It is, however, well within the skill of the art to determine the amount of active ingredient required.

Modification of the plants may be accomplished by applying the active ingredient to seeds, emerging seedlings, roots, stems, leaves, flowers, fruits or other plant parts. Such application may be made directly to the plant part, or indirectly by application to the plant growth medium.

Utilizing the isoxazole-5-yl-benzoates as the active ingredient in a plant growth regulating composition, said compounds were found to possess plant growth regulating activity when tested in accordance with the following procedure.

Soybean plants, variety Clark 63, were grown in a greenhouse or a growth chamber to the one-half expanded unifoliate stage. At that time, the plants were treated by dipping the plants into an aqueous solution of the chemical, acetone and a surfactant. After growing the plants for approximately two weeks under cool conditions (11-T4°C), the plants were transferred to a greenhouse and grown at 24°C.

Approximately four weeks after treatment, the plants were observed and compared with control plants that had been dipped into water containing only the surfactant. Results are summarized by Table III TABLE III Compound of Chemi cal Concentrati on example (PPm) 3 133 400 Observations Stature reduction, axillary bud development Stature reduction, axillary bud development. 266 Stature reduction, axillary bud development, dark foliar colour, inhibition of apical development. 6 133 Stature reduction, axillary bud development, leaf inhibition. 133 Stature reduction, axillary bud development, stem distortion, leaf distortion leaf inhibition, inhibition of apical development. 133 Stature reduction, epinasty, stimulation of axillary bud development, leaf inhibition.

The compound of Example 3 was further tested as follows.

A number of soybean plants, variety Williams, were grown from seeds in plastic pots in the greenhouse for a period of one week at which time the plants are thinned to one plant per pot. When the second trifoliate leaf (three weeks) was fully expanded, the plants were treated with a solution of the active ingredient in acetone and water.

Aqueous Tween 20 was used as a surfactant. (Tween is a trade mark).

When the fifth trifoliate leaf (four to five weeks) was fully expanded, the treated plants were compared with the non-treated control plants and the observations recorded. At rates of 2.8, 0.56 and 0.112 kilograms per hectare, the treated plants were observed to have undergone a reduction in stature, leaf alteration, rosette growth, altered canopy and inhibition of apical development.

The compound of Example 3 was also tested on various species of trees. Seedlings of said trees were potted anu placed in the greenhouse after they had been subjected to a cold temperature environment (4°C) for a period of approximately two months.

When the buds broke and new growth appeared, the trunk and foliage were treated with an aqueous solution of the compounds of Example 3, acetone, cyclohexanone and an emulsifier. Table IV summarizes the observations noted. 6956 TABLE IV Tree Species Rate mg/pi ant Observation Period (Days) after Treatment Observations Black Locust 50 7-29 Stature reduction, leaf epinasty, leaf inhibition inhibition of branch growth. Northern Red Oak 20 28 Stature reduction, leaf epinasty, stimulation of axillary buds, leaf inhibition, inhibition of apical development. American Sycamore 8 70 Stature reduction, leaf epinasty, stimulation of axillary buds, leaf alteration, leaf inhibition, inhibition of apical development, inhibition of branch growth, enlarged nodes, increased number of branches at the node. American 4 70 Stature reduction, leaf Sycamore epinasty, stimulation of axillary buds, leaf alteration, leaf inhibition, inhibition of apical development, inhibition of branch growth, enlarged nodes, increased number of branches at the node. 2 70 Stature reduction, leaf epinasty, stimulation of axillary buds, leaf alteration, leaf inhibition, inhibition of apical development, inhibition of branch growth, enlarged nodes, inceased number of branches at the node.

The compound of Example 3 was formulated as an aqueous solution of acetone, cyclohexanone and an emulsifier. Sugarbeet plants at the 5 to 7 leaf stage were treated with said formulation by wetting the leaves thereof,. Table V summarizes the results of observations taken 28 to 126 days after treatment. 4695θ TABLE V Rate (ppm) Observations Stature reduction, leaf inhibition, axillary bud development. 100 Stature reduction, leaf inhibition, reduced beet size, axillary bud development.

The compounds of the invention have been found to be effective in regulating the growth of various monocotyledonous plants as well as dicotyledonous. The compound of Example 3 was treated on various lawn grasses as follows. A mixture of Kentucky Bluegrass, Creeping Red Fescue and Chewings Fescue were planted in a good grade of top soil in plastic pots. Seven to ten days after termination, the plants were treated with the active ingredient to which a surfactant had been added by spraying the plants until they were wet with various concentrations. Results are summarized in Table VI.

TABLE VI 2θ Height (2 of Control) at Rate (ppm) 3 Weeks After Treatment 9 Weeks After Treatment 10 102 93 50 94 87 250 66 57 6 9 5 6 The compound of Example 3 was applied to four-week old Bluebell rice at a rate of 250 ppm. When compared with the control, stature reduction and tillering were noted both at 3 weeks and 7 weeks after treatment.

The compound of Example 3 was also applied to four-week old grain sorghum at a rate of 250 ppm. Results are summarized in Table VII.

TABLE VII Weeks After Treatment 7 Plant Height (2 of Control Other Observations Chlorosis necrosis Necrosis Table VIII, below summarizes observations made when the compound of Example 3 was applied to Larber barley.

TABLE VIII Time of Treatment Time of Observation (Weeks after Treatment) Concentration (ppm) Plant Height (2 of Control 16 days 3 250 90 16 days 6 250 97 42 days 3 10 93 42 days 3 50 106 42 days 3 250 90 46936 Table IX summarizes observations made when compound 3 was applied to Cheyenne wheat.

TABLE IX Time of Treatment Time of Observation (Weeks after Treatment) Concentration (PPm) Plant Height (% of Control) 15 days 3 250 80 15 days 6 250 93 42 days 3 10 113 42 days 3 50 112 42 days 3 250 109 The above data illustrate that the compounds of the invention may be used as a herbicide or a plant growth regulant for regulation of monocotyledonous or dicotyledonous plants. When used as a herbicide, it is desirable that rates of application above 2.24 kilograms per hectare be utilized. When used to regulate the growth of desirable plants, rates below 5.6 kilograms per hectare especially 0.056 to 3.36 are preferred.

In selecting the appropriate time the rate of application of the active ingredient, it will be recognized that precise rates will also be dependent upon the desired response, mode of application, plant variety, soil conditions and various other factors known to those skilled in the art. While a rate of about 0.056 to 5.6 kilos per hectare is preferred, higher rates of up to 56 kilos per hectare may be used, depending upon the factors noted above. In addition, it will be recognized that single or multiple applications may be used to exert the desired response.

In the practice of the invention, the active ingredient can be used alone or in combination with other pesticides or a material referred to in the art as an adjuvant in either liquid or solid form. To prepare such compositions, the active ingredient is mixed with an adjuvant including diluents, extenders, carriers and conditioning agents to provide compositions in the form of finely-divided particulate solids, granules,pellets, wettable powders, dusts, solutions and aqueous dispersions or emulsions. Thus, the active ingredient can be used with an adjuvant such as a finely-divided particulate solid, a solvent liquid of organic origin, water, a wetting agent, dispersing agent or emulsifying agent or any suitable combination of these.

Illustrative finely-divided solid carriers and extenders which are useful in plant growth regulating compositions of this invention include the talcs, clays, pumice, silica, diatomaceous earth, quartz, Fullers earth, sulfur, powdered cork, powdered wood, walnut flour, chalk, tobacco dust, and charcoal. Typical liquid diluents include Stoddard solvent, acetone, alcohols, glycols, ethyl acetate and benzene. The plant growth regulating compositions of this invention, particularly liquids and wettable powders, usually contain one or more surface-active agents in amounts sufficient to render a given composition readily dispersible in water or in oil. The term surface-active agent is understood to include wetting agents, dispersing agents, suspending agents and emulsifying agents. Such surface-active agents are well known and reference is made to U.S. Patent No. 2,547,724, Columns 3 and 4, for detailed examples of the same.

Generally, the active ingredients are applied in the form of a composition containing one or more adjuvants which aid in the application of a uniform distribution of the active ingredient. The application of liquid and particulate solid . compositions of the active ingredient can be carried out by conventional techniques utilizing, for example, spreaders, power dusters, boom and hand sprayers and spray dusters. The compositions can also be applied from airplanes as a dust or spray.

Compositions of this invention generally contain from about to 99 parts active ingredient, about 1 to 50 parts surface-active agent and about 4 to 94 parts solvent, all parts being by weight based on the total weight of the composition.

Claims

1. CL A IH S

1. A compound having the formula wherein A is R is hydrogen, lower alkyl or agriculturally acceptable cations; providing that B may be pyridyl only when n is 0.

2. A compound according to Claim 1 wherein £ is 1.

3. A compound according to Claim 1 which is methyl 2* £*3 -^3(trifluoromethyl)phenylj - 5 - isoxazolyij benzoate.

4. A compound according to Claim 1 wherein £ is 0.

5. A compound according to Claim 4 wherein B is

6. A compound according to Claim 1 having a phenyl group substituted by a trifluoromethyl group in the meta position.

7. A method for preventing the growth of undesirable vegetation which comprises applying to said vegetation a herbicidally effective amount of a compound having the formula -CH c wherein A is R is hydrogen, lower alkyl or agriculturally acceptable cations; providing that B may be pyridyl only when £ is 0.

8. A method according to Claim 7 wherein jn is 1.

9. A method according to Claim 7 wherein said compound is methyl 2-(3-(3- (trifluoromethyl)phenyfj - 5 - isoxazolyl] benzoate.

10. A method according to Claim 7 wherein ji is 0.

11. A method according to Claim 10 wherein B is CF,

12. A method according to Claim 7 wherein the compound has a phenyl group substituted by a trifluoromethyl group in the meta position.

13. A method according to any of Claims 7 to 11 wherein the compound is applied at a rate of application above 2.24 kilograms per hectare.

14. A method according to any of Claims 7 to 13 wherein the 5 compound is applied to a plant referred to herein as F to P in Table I or as C or G to J in Table II.

15. A method of regulating the growth of undesirable plants which comprises applying to said plants an effective amount of a compound having the formula wherein A is ; and B is pyridyl or ; n is 0 or 1; and R is hydrogen, providing that lower alkyl or agriculturally ί may be pyridyl only when n acceptable cations; is 0. 46356

16. A method according to Claim 15 wherein ji is 1.

17. A method according to Claim 15 wherein said compound is methyl 2 -^3 -(j3 ' (tri fluoromethyl) phenyl J - 5 - isoxazolyl]benzoate.

18. A method according to Claim 15 wherein n is 0.

19. A method according to Claim 18 wherein B is

20. A method according to Claim 15 wherein the compound has a phenyl group substituted by a trifluoromethyl group in the meta position.

21. A method according to any of Claims 15 to 19 wherein the compound 10 is applied to a plant at a rate of application of from 0.056 to 3.36 kilograms per hectare.

22. A method according to any of Claims 15 to 21 wherein the regulation takes the form of stature reduction.

23. A method according to any of Claims 15 to 22 wherein the regulation 15 effects axillary bud development.

24. A method according to any of Claims 15 to 23 wherein the plant is selected from legumes, trees and sugarbeets.

25. An agricultural chemical composition comprising an adjuvant and from 1 to 99 parts by weight of a compound having the formula A—C -CH II w N £— B wherein A is or ; and B is pyridyl Wl-n Λ ; ji is 0 or 1; and ( c o 2 R) n R is hydrogen, lower alkyl, or agriculturally acceptable cations; providing that B may be pyriclyl only when ji is 0. 10

26. A composition according to Claim 25 wherein ji is 1.

27. A composition according to Claim 25 wherein said compound is methyl 2 -03 -£3 - (trifluoromethyl)phenyl] - 5 - isoxazolyj] benzoate.

28. A composition according to Claim 25 wherein n is 0.

29. A composition according to Claim 28 wherein B is // \

30. A composition according to Claim 25 wherein the compound has a 5 phenyl group substituted with a tri fluoromethyl group in the meta position.

31. A composition according to any of Claims 25 to 29 that comprises a surface-active agent.

32. A composition according to Claim 31 which comprises from 1 to 99 parts of the compound, from 1 to 50 parts of surface-active agent 10 and from 4 to 94 parts of solvent per 100 parts by weight based on the total weight of the composition.

33. A composition according to any of Claims 25 to 32 which takes the form of a finely-divided particulate solid, a granule, a pellet, a wettable powder, a dust, a solution, an aqueous dispersion or an 15 aqueous emulsion.