IE52031B1 - Trialkylsulf(ox)onium salts of n-phosphonomethylglycine,their production,their use as plant growth regulators and herbicides and compositions containing them - Google Patents

Abstract

Novel tri-mixed alkylsulfonium salts of N-phosphonomethylgly-cine are disclosed herein, having the formula < IMG > in which R1, R2, are R3 represent C1-C6 alkyl and n is zero or one, wherein no more than two of R1, R2, or R3 are identical. The compounds are useful in regulating the natural growth or development of plants and as herbicides.

Description

Ihls Invention is directed to novel chemical compounds and their use in regulating the natural growth or development of plants. In particular, this invention relates to the chemical treatment of plants to alter their natural growth or development for the purpose of enhancing various agricultural or horticultural features of the plants, and also to the control of undesirable vegetation.

It is well known among those skilled in the art of agriculture and horticulture that various features of plant growth can be modified or regulated to produce a variety of beneficial effects. lo For instance, certain types of treatment can produce defoliation of a plant in a beneficial manner, i.e., inhibiting further leaf growth while permitting further development of the productive plant parts. As a result, the productive parts demonstrate extra growth, and subsequent harvesting operations are facilitated. Defoliants are parti15 cularly useful in flax, cotton, and bean crops, and other crops of a similar nature. Although defoliation results in the killing of leaves, it is not a herbicidal action per se since the remainder of the plant is unharmed. Indeed, killing of the treated plant is undesirable when . defoliation is sought, since leaves will continue to adhere to a dead plant.

Another response demonstrated by plant growth regulants is the general retardation of vegetative growth. This response has a wide variety of beneficial features. In certain plants it causes a diminution - 3 or elimination of the normal apical dominance, and thus leads to a shorter main stem and increased lateral branching. This alteration of the natural growth or development produces smaller, bushier plants which often demonstrate Increased resistance to drought and pest infestation.

The retardation of vegetative growth in turf grasses is particularly desirable. When the vertical growth rate of such grasses is lessened, root development Is enhanced and a denser, sturdier turf is produced.

Die retardation of turf grasses also serves to increase the interval between mowings of lawns, golf courses and similar grassy areas.

In many types of plants, such as silage crops, potatoes, sugar cane, beets, grapes, melons and fruit trees, the retardation of vegetative growth results in an Increase In the carbohydrate content of the plants at harvest. It Is believed that the retardation or suppression of such growth at the appropriate stage of development causes less of tne 15 available carbohydrate to be consumed for vegetative growth and results in an enhanced starch and/or sucrose content. Retardation of vegetative growth in fruit trees is demonstrated by shorter branches and greater fullness of shape, and often results in lesser vertical elongation.

Diese factors contribute to the ease of access to the orchard and simpli2o fy the fruit harvesting procedure.

It has now been discovered that novel tri-mixed alkylsulfonium salts of Ν-phosphonomethylglyclne are useful in both regulating the natural growth or development of plants and in controlling undesirable vegetation. These salts have the formula Ro-S(0)n© Θ 0,0 0 I \H 1' Ri \>-CH2NHCH2C0H HX where R^, Rg/ ^3 represent Cj-Cg alkyl, and n is zero or one, wherein no more than two of R^, Rj and Rj are identical. Preferably, R^, Rj and Rj each represent C^-C^ alkyl, wherein no more than two of R^, Rj and Rj are identical. - 4 This Invention further relates to a method of regulating the natural growth or development of plants comprising applying to said plants an effective, plant-regulating, non-lethal amount of the above compounds, as well as a method of controlling undesirable vegetation comprising applying a herbicidally effective amount of the compounds to such vegetation when the latter is In a postemergence state.

As employed herein, the term natural growth or development designates the normal life cycle of a plant in accordance with its genetics and environment, in the absence of artificial external influences.

A preferred utility of the instant compounds is in increasing the sucrose yield of field grown sugarcane and sorghum. The tern regulating is used herein to denote the bringing about through chemical means of any temporary or permanent modification or variation from the normal life cycle short of killing the plant.

The term herbicidally effective amount designates any amount of the compounds disclosed herein which will kill a plant or any portion thereof. By plants is meant germinant seeds, emerging seedlings, and established vegetation, including roots and above-ground portions. Herbicidal effects include killing, defoliation, desiccation, stunting, leaf bum, and dwarfing. Herbicidal effects are generally achieved at higher application rates than growth regulating effects.

The term alkyl is used herein to include both straight- chain and branched-chain alkyl groups. The carbon atom range is intended to be inclusive of its upper and lower limits; for example, methyl, ethyl, n-propyl, isopropyl, butyl, n-butyl, sec.-butyl, pentyl, isopentyl, neopentyl, sec.-pentyl, hexyl, isohexyl and sec.-hexyl. However, no more than two of said alkyl moieties are identical.

Examples of specific compounds falling within the above formula are: diethylmethyl sulfonium salt of N-phosphonoglycine dimethylethyl sulfoniun salt of N-phosphonoglycine - 5 dlethylisopropyl sulfonium salt of N-phosphonoglycine diethyl-n-butyl sulfonium salt of N-phosphonoglycine di-n-butylmethyl sulfonium salt of N-phosphonoglycine dimethyl-n-butyl sulfoniun salt of N-phosponoglycine dimethylisopropyl sulfonium salt of N-phosphonoglycine In accordance with the present invention, regulation of the natural growth or development of plants is achieved by the direct application of a conpound within the above formula or a formulation of such a conpound to the plants or to any of their above-ground portions at approximately 4 to 10 weeks prior to harvest. With properly controlled application, a growth regulating effect can be achieved without herbicidal results. Hie amount which constitutes an effective amount varies not only with the particular material selected for treatment, but also with the regulatory effect to be achieved, the species of plant being treated and its stage of development, and whether a permanent or transient effect is sought. Other factors which bear upon the determination of an appropriate plant regulating amount include the manner of application and weather conditions such as temperature or rainfall. Growth regulation may arise fran the effect of the compound on either the physiological processes or the morphology of the plant, or from both in combination or in sequence. Morphological changes are generally noticeable by observable changes in the size, shape, color or texture of the treated plant or any of its parts, as well as in the quantity of fruit or flowers produced.

Changes in physiological processes, on the other hand, occur within the treated plant and are usually hidden from the eye of an observer. Changes of this type most often occur in the production, location, storage or use of chemicals naturally occurring in the plant, such as hormones. Physiological changes may be visually detectable when followed by a change in morphology. In addition, numerous analytical procedures for determining the nature and magnitude of changes in the various physiological processes are known to those skilled in the art. - 6 The compounds of the present invention serve to regulate the natural growth or development of treated plants in a number of diverse ways, and it is to be understood that each compound may not produce identical regulatory effects on each plant species or at every rate of appli5 cation. As stated above, responses will vary in accordance with the compound, the rate and the plant.

Herbicidal effects are achieved in a similar manner, and the strength of the application can be varied to achieve the desired result.

The compounds of this invention are readily prepared from 10 N-phosphonomethylglycine by reacting the latter with silver oxide to form the silver salt or with sodium hydroxide to form the sodium salt, and treating either the silver or sodium salt witii a trialkylsulfonium or -sulfoxonium halide. Alternatively, tile glycine can be reacted directly with the trialkylsulfonium or -sulfoxonlun halide in the presence of propylene oxide. N-Phosphonomethylglycine is a conraereially available material known by the comnon name glyphosate. It can be prepared by the phosphonomethylation of glycine, the reaction of ethyl glycinate with formaldehyde and diethylphosphite, or the oxidation of the N-phosphinomethylglycine. Such methods are described in O.S. Patent No. 3,799,758 (Franz, March 26, 197*0« As illustrated in the examples which follow, the compounds of the invention can either regulate the natural growth or development of plants or kill weeds. While regulatory responses are often desirable in their own right, their effect cn crop economics is most often of primary significance. Thus, increases in the yield of individual plants, increases in the yield per unit area, and reductions in the cost of harvesting and/or subsequent processing are all to be considered in assessing the consequence of an individual regulatory effect during the growth or development of a plant.

Die specific exanples which follow are presented as merely illustrative, non-limiting demonstrations of the preparation of the canpounds of the present invention and of their effectiveness in regulating the growth of plants and in controlling undesirable vegetation. - 7 EXAMPLE I Di-n-buty imethyl sulfonlum Salt of N-phosphonomethylglyclne A reaction vessel was cterged with 50 milliliters (ml) of water, 5-1 grams (g) (0.03 mole) of N-phosphonomethylglycine, and 8.65 g (0.03 mole) of dl-n-butylmethyl sulfoxonyl Iodide. Ihe vessel was additionally charged with 2.2 g (0.0375 mole) of propylene oxide. The entire reaction mixture was allowed to stand at room temperature overnight. At the end of this time, the reaction mixture was extracted three times with diethyl ether and phase separated. Die aqueous phase was stripped, yielding 11.1 g. This product was triturated with tetrahydrofuran (2 x 10 ml), then once with 10 ml acetone and stripped to yield 11.0 g of product. This product was further triturated with 20 ml of acetone and then with 10 ml diethyl ether and stripped. There was obtained a low melting solid, yield 9-8 g. The molecular structure of the product was confirmed by proton-nuclear magnetic resonance as the title compound.

EXAMPLE II Dlethylmethyl sulfonlum Salt of N-phosphonanethylglycine In a similar procedure as Example I, 50 ml of water, 6.76 g (0.04 mole) of N-phosphonomethylglycine, 9.3 g (0.04 mole) of diethylmethyl sulfoxonyl iodide and 2.9 g (0.05 mole) of propylene oxide were reacted overnight at room temperature, extracted 3 times with diethyl ether and the aqueous phase stripped of volatile (yield 12.3 g). After trituration with acetone and diethyl ether and stripping of volatiles, there was obtained 12.0 g of the title compound (decomposes at 60-65°C). The molecular structure of the product was confirmed by proton-nuclear magnetic resonance as that of the title compound.

EXAMPLE ΙΠ Dlmethyllsopropyl sulfonlum Salt of N-phosphonomethylglycine In a similar procedure as Exanple I, 50 ml of water, 6.76 g (0.04 mole) of N-phosphonanethylglycine, 9·3 g (0.04 mole) of dimethylisopropyl sulfoxonyl iodide and 3·5 g (0.06 mole) of propylene oxide were reacted overnight at roan temperature, extracted 2 times with diethyl ether and the aqueous phase stripped (yield 11.8 g). After trituration with acetone (2 times, 10 ml each) the product was stripped again to yield 11.2 g, ηρ3θ 1.5232. The molecular structure of the product - 8 w.-κ! conl'lrnuxl by proton nuclear magnet Lc rcsonsancc ;u; that of the titLe cuiii|jounil.

EXAMPLE IV Dimethyl-n-butyl sulfonium Salt of N-phosphonomethylglycine In a similar procedure as Exanple I, 50 ml of water, 6.8 g (0.04 mole) of N-phosphonomethylglycine, 10.0 g (0.04 mole) of dlmethyln-butyl sulfoxonyl iodide and 3.5 g (0.06 mole) of propylene oxide were reacted overnight at roan temperature, extracted 2 times with diethyl ether, phase separated, and stripped of volatiles (yield 12.4 g). After trituration with acetone (2 times, 10 ml each) and stripping, there was obtained 12.9 g of a hygroscopic white solid. 'Bie molecular structure of the product was confirmed by proton-nuclear magnetic resonance as the title conpound.

Other conpounds within the scope of the generic formula shown above can be prepared by either of these methods with appropriate starting materials.

This exanple demonstrates the post-emergence herbicidal activity of the conpounds prepared in Exanples I and II.

Aluminium planting flats measuring 15.2 x 22.9 x 8.9 on were filled to a depth of 7.6 em with loamy sand soil, containing 50 parts per million (ppn) each of the conmercial fungicide cis-N/Ctrichlorcmethyl)thio7-4-cyclohexene-l,2-dicarboximide (Captan, Captan is a Trade Mark) and. 17-17-17 fertilizer (percentages of N-P2O^-K2O) on a weight basis). Several rows were impressed across the width of each flat and a variety of seeds of both grass and broadleaf weed species were planted, one species per row. The weed species used are listed below: Grasses: A. Yellow nutsedge Cyperus esculentus B. Foxtail C. Watergrass D. Wild oat Setaria sp. Echinochloa erusgalli Avena fatua Iπ·'ι·ΐ' 11 ·•al' wf.1.!;!: E. Curly dock Rumex crlspus F. Annual momining glory Ipomoea purpurea G. Velvetleaf Abutilon theophrastl H. Mustard Brassloa sp. lhe broad leaf species were seeded first, and the grasses were seeded four days later. Ample seeds of each species were planted to produce 20 to 50 seedlings per row after emergence, depending on the size of each plant.

Ten days after the grasses were seeded, the emerged seedlings 10 of all species were sprayed with aqueous solutions of the test compounds.

The solutions were prepared to such dilutions that a spray rate of 80 gallons per acre (750 liters per hectare) gave 4.0 pounds of test ccmpound per acre (4.48 kilograms per hectare) as desired for the test. Additional control flats not treated at all were used as standards for comparison to measure the extent of weed control in the treated flats.

Nineteen days later, the test flats were compared to the standards and the weeds in each row were rated visually in terms of percent control ranging from 0% to 100%, with 0% representing the same degree of growth as the same row in the standard and 100% representing complete kill of all weeds in the row. All types of plant injury were taken into consideration. The results are shown in Table I.

TABLE I HERBICIDAL TEST RESULTS Test Compound Application Rate (lb/A) Grass Weeds A B C D Percent Control Broadleaf Weeds E F G H N-phosphonomethyl- * glycine, di-n-butyl 4.0 methyl sulfoniun salt N-phosphonomethylglycine, diethylmethyl 4.0 sulfoniun salt 100 90 90 50 80 75 90 90 60 55 65 50 * 4.48 kg/ha - 10 METHODS OF APPLICATION Whether used as plant growth regulators or as herbicides, the compounds of the present invention are most useful when applied directly to the plants subsequent to their emergence fran the soil. In use at an agricultural field site, the conpounds are generally embodied in suitable formulations containing additional ingredients and diluent carriers to aid in their dispersal. Examples of such ingredients or carriers are water, organic solvents, dusts, granules, surface active agents, waterin-oil and oil-in-water emulsions, wetting agents, dispersing agents, and emulsifiers. The formulations generally take the form of dusts, solu10 tions, anulsifiable concentrates, or wettable powders.

A. DUSTS Dusts are dense powder compositions which combine the active compounds with a dense, free-flowing solid carrier. They are intended for application in dry form and are designed to settle rapidly to avoid being windbome to areas where their presence is not desired. lhe carrier may be of mineral or vegetable origin, and is preferably an organic or inorganic powder of high hulk density, low surface area, and low liquid absorptivity. Suitable carriers include micaceous talcs, pyrophyllite, dense kaolin clays, tobacco dust, and ground calcium phosphate rock.

The performance of a dust is sometimes aided by the inclusion of a liquid or solid wetting agent, of ionic, anionic, or nonionic character. Preferred wetting agents include alkylbenzene and alkylnaphthalene sulfonates, sulfated fatty alcohols, amines or acid amides, long chain acid esters of sodium isothionate, esters of sodium sulfosuccinate, sulfated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated vegetable oils, and dltertiary acetylenic glycols. Dispersants are also useful in the same dust compositions. Typical dispersants include methyl cellulose, polyvinyl alcohol, lignin sulfonates, polymeric alkylnaphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bis30 naphthalenesulfonate, and sodium-N-methyl-N-(long chain acid) taurates. - 11 In addition, inert absorptive grinding aids are frequently included in dust compositions to aid in tbe manufacturing of the dust. Suitable grinding aids include attapulgite clay, diatomaceous silica, synthetic fine silica and synthetic calciun and magnesiun silicates.

In typical dust compositions, carriers are usually present in concentrations of fran about 30 to 90 weight percent of the total composition. The grinding aid usually constitutes about 5 to 50 weight percent, and the wetting agent up to about 1.0 weight percent. Dispersants, when present, constitute up to about 0.5 weight percent, and minor amounts of anticaking and antistatic agents may also be present. The particle size of the entire composition is usually about 30 to 50 ym.

B. SOLUTIONS Aqueous solutions of the active compounds are prepared such that application at the rate of about 1 to 2OO gallons of solution per acre (about 9 to 1875 liters per hectare) will provide the required amount of active ingredient. A small amount of non-phytotoxlc surfactant typically between 0.05% and 0.5% by weight is usually included to improve the wetting ability of the solution and thus its distribution over the plant surface. Anionic, cationic, nonionic, ampholytic, and 20 zwitterionic surfactants are all useful in this regard.

Suitable anionic surfactants include alkali metal, ammonium, and amine salts of fatty alcohol sulfates having from 8-18 carbon atoms in the fatty chain and sodium salts of alkyl benzene sulfonates having from 9 to 15 carbon atoms in the alkyl chain. Suitable cationic surfac25 tants include dimethyl dialkyl quaternary amnonium halides with alkyl chains of 8 to 18 carbon atoms. Suitable nonionic surfactants include polyoxyethylene adducts of fatty alcohols having 10 to 18 carbon atoms, polyethylene oxide condensates of alkyl phenols with alkyl chains of 6 to 12 carbon atoms and 5 to 25 moles of ethylene oxide condensed onto each mole of alkyl phenol, and polyethylene oxide condensates of sorbitan esters with 10 to 40 moles of ethylene oxide condensed onto each mole of sorbitan ester. Suitable ampholytic surfactants include secondary and tertiary aliphatic amine derivatives with one aliphatic substituent - 12 containing 8 to 18 carbon atoms and another containing an anionic watersolubilizing group such as a sulfate or sulfonate. Sodium-3-dodecylaminopropionate and sodiuni-3-dcdecyl amino propane sulfonate are examples. Suitable zwitterionic surfactants include derivatives of aliphatic quaternary ammonium conpounds with one aliphatic substituent containing 8 to 18 carbon atoms and another containing an anionic water-solubilizing group. Exanples thereof are 3-(N,N-diirEthyl-N-hexadecylaitrrcnio)propane-l-sul fonate and 3-(N,N-dimethyl-N-hexadecylanmonio)-2-hydroxy propane-lsulfonate.

C. EMULSIFIABLE CONCENTRATES Etaulsifiable concentrates are solutions in vhich the active materials and an emulsifying agent are dissolved in a non-watermiscible solvent. Prior to use, the concentrate is diluted with water to form a suspended emulsion of solvent droplets.

Typical solvents for use in snulsifiable concentrates include weed oils, chlorinated hydrocarbons, and non-water-miscible ethers, esters, and ketones.

Typical emulsifying agents are anionic or nonionic surfactants, or mixtures of the two. Examples Include long-chain mercaptan polyethoxy alcohols, alkylaryl polyethoxy alcohols, sorbitan fatty acid esters, polyoxyethylene ethers with sorbitan fatty acid esters, polyoxyethylene glycol esters with fatty or rosin acids, fatty alkylol amide condensates, calcium and amine salts of fatty alcohol sulfates, oil-soluble petroleum sulfonates, or preferably mixtures of these emulsifying agents. Such emulsifying agents usually comprise about 1 to 10 weight percent of the total conposition.

Typical emulsifiable concentrates contain about 15 to 50 weight percent active material, about 40 to 82 weight percent solvent, and about 1 to 10 weight percent airulsifier. Other additives such as spreading agents and stickers can also be included. - 13 D. WETTABLE POWDERS Wettable powders are water-dispersible compositions containing the active material, an inert solid extender, and one or more surfactants to provide rapid wetting and prevent flocculation when suspended in water.

Suitable solid extenders include both natural minerals and materials derived synthetically from such minerals. Examples Include kaolinites, attapulgite clay, montmorillonite clays, synthetic silicas, synthetic magnesiun silicate and calciun sulfate dihydrate.

Suitable surfactants include both nonionic and anionic types, and function as wetting agents and dispersants. Usually one of each is included. Preferred wetting agents are alkylbenzene and alkylnaphthalene sulfonates, sulfated fatty alcohols, amines or acid amides, long chain acid esters of sodium isothionate, esters of sodium sulfosuccinate, sulfated or sulfonated fatty acid esters, petrolean sulfonates, sulfonated vegetable oils, and ditertiary acetylenic glycols. Preferred dispersants are methyl cellulose, polyvinyl alcohol, lignin sulfonates, polymeric alkylnaphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bisnaphthalenesulfonate, and sodlum-N-methyl-N(long chain acid) taurates.

Typical wettable powders contain 25 to 90 percent active material, 0.5 to 2.0 percent wetting agent, 0.25 to 5.0 percent dispersant, and from 9.25 to 74.25 weight percent inert extender. Frequently, 0.1 to 1.0 percent of the extender is replaced by a corrosion inhibitor and/or an antifoaming agent.

E. DJ GENERAL In general, any conventional postemergence method of application can be used, including conrnon dusting or spraying equipment. The amount of active ingredient which is effective in producing the desired result, be it herbicidal or growth-regulating, depends on the nature of the plant species to be controlled and the prevailing conditions. Herbicidal effects are usually achieved at 0.1 to 50 pounds active ingredient per acre (0.112 to 56 kg/ha), preferably 1 to lo (1.12 to 11.2), while plant growth regulation is usually - 14 achieved at 0.1 to 20 pounds active ingredient per acre (0.112 to 22.4 kg/ha), preferably 0.5 to 5 (0.56 to 5.6). It will be readily apparent to one skilled in the art that canpounds of lower activity will require a higher dosage than more active compounds for the same degree of control.

Claims (9)

1. CLAIMS:1. A compound having the formula R 3 I R--S(O) ® ® 0 0 0 2 I n \JI II R x P-CH 2 NHCH 2 COH HO where Rj, R 2 , and Rj each represent Cj-Cg alkyl, and n is zero or one, no more than two of Rj, R 2 and Rj being identical.

2. A compound according to Claim 1, in which n is zero.

3. A compound according to Claim 1 or 2, in which Rj, R 2 and R 3 each represent Cj-C^ alkyl. 4. are A each compound according to Claim 2, n-butyl and R 3 is methyl. in which Rj and R 2 5. A compound according to Claim 2, in which Rj and R 2 are each ethyl and R 3 is methyl. 6. A compound according to Claim 2, in which Rj and R 2 are each methyl and R 3 is isopropyl. 7. A compound according to Claim 2, in which Rj and R 2 are each methyl and R 3 is n-butyl. 8. A compound according to Claim 1, in which n is one. 9. A process for the preparation of a compound as claimed in Claim 1, which comprises reacting the sodium or silver salt of N-phosphonomethylglycine with an appropriate trialkylsulf(ox)onium halide. 10. A process according to Claim 9, wherein the sodium or silver salt has been prepared by reacting sodium hydroxide or silver oxide with N-phosphonomethylglycine. 11. A process for the preparation of a compound as claimed in Claim 1, which comprises reacting N-phosphonomethylglycine with an appropriate trialkylsulf(ox)onium halide in the presence of propylene oxide. - 16 12. A herbicidal composition comprising a herbicidally effective amount of a compound as claimed in any one of Claims 1 to 8 and an inert diluent or carrier. 13. A method of controlling undesirable vegetation compris

4. 5 ing applying to the vegetation in post-emergent state a compound as claimed in any one of Claims 1 to 8 or a composition as claimed in Claim 12. 14. A compound of the formula given and defined in Claim 1 substantially as hereinbefore described with particular

5. 10 reference to Examples I-IV of the accompanying Examples.

6. 15. A process for the preparation of a compound of the formula given and defined in Claim 1, substantially as hereinbefore described with particular reference to Examples I-IV of the accompanying Examples. 15

7. 16. A compound of the formula given and defined in Claim 1, whenever prepared by a process claimed in a preceding claim.

8. 17. A herbicidal composition according to Claim 12, substantially as hereinbefore described.

9. 20 18. A method according to Claim 13 of controlling undesirable vegetation, substantially as hereinbefore described and exemplified.