CA1186328A - Tri-mixed alkylsulfonium salts of n- phosphonomethylglycine and their use as plant growth regulators and herbicides - Google Patents

Abstract

Abstract of the Disclosure Novel tri-mixed alkylsulfonium salts of N-phosphonomethylgly-cine are disclosed herein, having the formula

Description

TRI-MIXED ALKYLSULF~NIUM SALTS OF N-PHOSPHONOMETHYLGLYCIN~
AND THEIR USE AS PLANT GROWTH REGULATORS AND HERBICIDES

ack~ _d of the In~ention This invention is directed to novel chemical conpounds and their use in regulating the natural growth or develo~ment of plants. Ir.
particular, this invention relates to the chemical treatment of plan~s to alter their natural growth or develo~ment 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 `oe modified or regulated to produce a variety of beneficial effects.

For instance, certain tyoes of treatment can produce defoli-ation of a plant in a beneficial manner, i.e., inhibiting further leaf growkh while pe m itting further development of the productive plant parts. As a result, the productive parts d~monstrate extra growth, and subse~uent harvesting operations are facilitated. De~olian~s are parti-cularly useful in flax, cotton, and bean crops, and other crops of a slmilar 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 ls 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. m is response has a wide variety of beneficial features. In certain plants it causes a diminution ,, 632~

or elimination of the normal apical dominance, and thus leads to a shorter main stem and increased lateral branching. qhis alteration of the natural growth or development produces smaller, bushier plants ~lhich often demonstrate increased resistance to drought and pest infestation.
m e retardation of vegetative growth in turf grasses is particularly desirable. When the vertical growth rate of such grasses is lessened, root developrnent is enhanced and a denser, sturdier turf is produced.
The 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 vegeta-tive 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 the 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.
These factors contribute to the ease of access to the orchard and simpli-fy the fruit harvesting procedure.
Brief Description of the Invention It has now been discovered that novel tri-mixed alkylsulfonium salts of N-phosphonomethylglycine are useful in both regulating the natural growth or development of plants and in controlling undesirable vegetation. Ihese salts have the formula ~3 R2-S(O)n~3 ~ \1l 1 Rl ~P-CH2NHCH2COH

where Rlg R2, and R3 represent Cl-C6 alkyl, and n is zero or one, wherein no more than two of Rl, R2 or R3 are identical. Preferably, Rl, R2, and R3 each represent Cl-C4 alkyl, wherein no ~.ore than two of Rl, R2 or R3 are identical.

11~6328 This invention further relates to a method of regulating the natural growth or development of plants comprising applyin3 to sa~d plants an effective, plant-regulating, non-lethal amount of the above compounds, as well as a method of controlling undesirable vegetation com-prising applying a herbicidally effective amount of the compounds to suchvegetation 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 gene-tics 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 ter~ "regulating'l is used herein to denote tne 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 'therbicidally e~fective amount" designates any a~ount of the compounds disclosed herein which will kill a plant or any portion thereof. By "plants" is meant germlnant seeds, emerging seedlings, and established vegetation, including roots and above-ground portions. Herb-icidal effects include killing, defoliation, desiccation, stunting, leaf burn, and dwarfing. Herbicidal effects are generally achieved at higher application rates than growth regulating effects.

m e term "aIkyl" is used herein to include both straight- chain and branched-chain alkyl groups. m e carbon atom range is intended to `ce inclusive of its upper and lower limits; for example, methyl, ethyl3 n~propyl, isopropyl, butyl, n-butyl, sec.-butyl, pentyl, isopentyl, neo-pentyl, sec.-pentyl, hexyl, isohexyl, sec.-hexyl, and the like. Hence, the term "tri-mixed alkyl" represents alkyl substitutions in which the sulfonium cation contains three aIkyl moieties. 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 . , .

diethylisopropyl sulfoniwm salt of N-phosphono~lyc ne diethyl-n-butyl sulfonium salt of N-phoshonoglycine di-n-butylmethyl sulfonium salt of ~T-phosphonogl~cine dimethyl-n-butyl sulfonium salt of ~-phosponogl~cine dimethylisopropyl sulfonium salt of N-phosphonoglycine Detailed Desc_iption of the Invention In accordance with the instant invention, regulation of the natural growth or development of plants is achieved by the direct appli-cation of a compound within the above formula or a formulation of such a compound to the plants or to any of their above-ground portions at approximately 4 to 10 weeks prior to harvest. ~lith properly controlled application, a growth regulating effect can be achieved without herbici-dal results. ~he 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 o~ development, and ~hether a permanent or transient effect is sought. Other factors which bear upon the determination of an appro-priate plant regulating amount include the ma~ner of application and weather conditions such as temperature or rainfall. Growth regulation may arise from the effect of the compound on either the physiological processes or the morphology of the plant, or from both in combination or in sequence. ~orphological changes are generally noticeable by observ-able 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 pro-duced.

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 occurrin~ 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 determlning the nature and magnitude of changes in the various physiological processes are known to those skilled in t~le art.

. j 1~8~;328 ~ he compounds of the instant 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 iden-tical regulatory ef~ects on each plant species or at everJ rate of appii-cation. As stated above, responses will vary in accordance ~lith thecompound, the rate, the plant, etc.

Herbicidal effects are achieved in a similar ~nner, and the strength of t`ne application can be varied to achieve the desired result.

~ le compounds of this invention are readily prepared from 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 sodi~m salt with a trialkylsulfonium or -sulfoxonium halide. Alternatively, the glycine can be reacted directly with the trialkylsulfonium or -sulfoxonium halide in the presence of propylene oxide. N-Phosphonomethylglycine is a commercially available material known by the common name "glyphosate." It can be prepared by the phosphonomethylation of ~lycine, the reaction of ethyl glycinate with formaldehyde and diethylphosphite, or the oxidation of the ~-phosphino-methylglycine. Such methods are described in U.S. Patent No. 3,799,758 (~ranz, March 26, 1974).

As illustrated in the examples which follow, the compounds of the invention can either regulate the natural gro~th or develo~ment of plants or kill weeds. While reO~ulatory responses are often desirable in their own right, their effect on crop economics is most often of primary sig~ificance. Thus, increases in the yield of individual plants, increases in the yield per unit area, and reductions in the cost of har-vesting and/or subsequent processing are all to be considered in assess-ing the consequence of an individual regulatory effect during the growth or development of a plant.

The specific examples ~hich follow are presented as merely illustrative, non-limiting demonstrations of the preparation of the com-pounds of the instant invention and of their effectiveness in regulating the growth of plants and in controlling undesirable vegetation.

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E~AMPLE 1 Di-n-butylmethyl sulfonium Salt of N-phosphonomethylglyclne A reaction vessel was charged with 50 milliliters (ml) of water, 5.1 grams (g) (0.03 mole) of N-phosphonomethylglycine, and 8.65 g (0.03 mole) of di-n-butylmethyl sulfoxonyl iodide. The vessel ~as addi-tionally charged with 2.2 g (0.0375 mole) of propylene oxide. The entire 5 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. The 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 pro-duct. m is product was further triturated with 20 ml of acetone and thenwith 10 ml diethyl ether and stripped. Ihere 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
Diethylmethyl sulfonium Salt of N-phosphonomethylglycine In a similar procedure as Example I, 50 ml of water, 6.76 g 15 (0.04 mole) of N-phosphonomethylglycine, 9.3 g (0.04 mole) of diethyl-methyl 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 trlturation with acetone and diethyl ether and stripping of volatiles, 20 there was obtained 12.0 g o~ the title compound (decomposes at 60-65C).
The molecular structure of the product was confirmed by proton-nuclear magnetic resonance as that o~ the title compoundO

Dimethylisopropyl sulfonium Salt of N-phosphonomethylglycine In a si~ilar procedure as Example I, 50 ml of water, 6.76 g (0.04 mole) of N-phosphonomethylglycine, ~.3 g (0.04 mole) of dimethyl-25 isopropyl sulfoxonyl iodide and 3.5 g (O.o6 mole) of propylene oxide werereacted overnight at room temperature~ extracted 2 times with diethyl ether and the aqueous phase stripped (yield 11.8 g). .~fter trituration with acetone (2 times, 10 ml each) the product was stripped again to yield 11.2 g, nD3 1.5232. me molecular structure of the product ~1~632~

was confirmed by pro~on nuclear magnetic resonsance as that of the titie compound.

EXA,MPLE IV
Dimethyl-n-butyl sulfonium Salt of N-phosphonomethylglycine In a similar procedure as Example I, 50 ml of water, 6.8 g (0.04 mole) of N-phosphonomethylglycine, 10.0 g (0.04 mole) of dimethyl-n-butyl sulfoxonyl iodide and 3.5 g (o.o6 mole) of propylene oxide were reacted overnight at room 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. m e molecular structure of the product was confirmed by proton-nuclear magnetic resonance as the title compound.

Other compounds within the scope of the generic formula shown above can be prepared by either of these methods with appropria~e start-ing materials.

This example demonstrates the post-emergence herbicidal activi-ty of the compounds prepared in Examples I and II.

Aluminum planting flats measuring 15.2 x 22.9 x 8.9 cm were filled to a depth of 7.6 cm with loamy sand soil, containing 50 parts per million (ppm) each of the co~mercial fungicide cis-N[(trichloromethyl)-thio]-4-cyclohexene-1,2-dicarboximide (Cap~an~) and 17-17-17 fertilizer (percentages of N-P2Os-K2O) on a weight basis). Several rows were impressed across the width of each flat and a variety of seeds o~ both grass and broadlea~ weed species were planted, one species per row. The weed species used are listed below:

Grasses:
A. Yellow nutsedge Cyperus esculentus B. Foxtail Setaria sp.
25 C. Watergrass Echinochloa crusgalli D. Wild oat Avena fatua ..J

` ~863Z~3 Broadleaf weeds:
_ _ _ E. Curly dock Rumex crispus F. Annual mornining glory Ipomoea purpurea G. Velvetleaf Abutilon theophrasti H. Mustard Brassica sp.

The broad leaf species were seeded first, and the grasses were seeded four days later. Ample seeds of each species were planted to prG-duce 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 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 con-pound per acre (4.48 kilograms per hectare) as desired for the test.
Additional control flats not treated at ~11 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 stan-dards and the weeds i~ each row were rated visually in terms of percent control rangin~r from 0% to 100%, with 0% representing the same degree of growth as the same row in the standard and 100% representing complete kili of all weeds in the row. All types of plant injury were taken into consideration. Ihe results are shown in Table I.

TABLE I
HERBICIDAL TEST RESULTS

Percent Control ApplicationGrass WeedsBroadleaf Weeds _ Test Compound Rate (lb/A)A B C D E F G H
1 N-phosphonomethyl-glycine, di-n-butyl 4.0 70 100 90 90 80 50 80 75 methyl sulfonium salt

2 N-phosphonomethyl-glycine, diethylmethyl 4.0 75 90 90 60 60 55 65 50 sulfonium salt ~8~3~

MEIHODS 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 from the soil. In use at an agricultural field site, the compounds 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, water-in-oil and oil-in-water emulsions, wetting agents, dispersing agents, and emulsifiers. The formNlations generally take the form of dusts, solu-tions, emulsifiable concentrates, or wettable powders.

A. DUSTS

Dusts are dense powder compositions which combine the active com-pounds with a dense, free-flowing solid carrier. They are intended for application in dry form and are designed to settle rapidly to avoid being windborne to areas where their presence is not desired.

~he carrier may be of mineral or vegetable origin, and is pre-ferably an organic or inorganic powder of high bulk denslty, low surface area, and low liquid absorptivity. Suitable carriers include micaceous talcs, pyrophyllite, dense kaolin clays, tobacco dust, and ground calcium phosphate rock.

qhe performance of a dust is sometimes aided by the inclusion of a liquid or solid wetting agent, of ionic, anionic~ or nonionic char-acter. Preferred wetting agents include aIkylbenzene and alkylnaphtha-lene 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, sulfon-ated vegetable oils, and ditertiary acetylenic glycols. Dispersants are also useful in the same dust compositions. Typical dispersants include methyl cellulose, polyvinyl alcohol, lignin sulfonates, polyneric alkyl-naphthalene sulfonates, sodiun naphthalene sulfonate, polymethylene bis-naphthalenesulfonate, and sodium-N-methyl-N-(long chain acid) taurates.

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In addition, inert absorptive grinding aids are ~requently included in dust compositions to aid in the manu~acturi~g of the dust.
Suitable grinding aids include attapulgite clay, diatomaceous silica, synthetic fine silica and synthetic calcium and magnesi~m silicates.

In typical dust compositions, carriers are usually present in concentrations of frcm about 30 to 90 weight percent of the total compo-sition. The grinding aid usually constitutes about 5 to 50 weight per-cent, and the wetting agent up to about 1.0 weight percent. Dispersants, ~hen present, constitute up to about 0.5 weight percent, and minor amounts of anticaking and antistatic agents may also be present. ~ne particle size of the entire composition is usually about 30 to 50 mic-rons.

B. SOLUTIONS
Aqueous solutions of the active compounds are prepared such that application at the rate of about 1 to about 200 gallons of solution per acre ~about 9 to about 1875 liters per hectare) will provide the required amount of active ingredient. A small amount of non-phytotoxic 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, ar.d 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 surfac-tants include dimethyl dialkyl quaternary ammonium halides with alkylchains of 8 to 18 carbon atoms. Suitable nonionic sur~actants 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 aIkyl 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 alld tertiary aliphatic amine derivatives with one aliphatic substituent ~63Z8 containing 8 to 18 carbon atoms and another containing an anionic ,rater-solubilizing group such as a sulfate or sulfonate. Sodiur~3-dodecyl-aminopropiona-te and sodium-3-dodecyl amino propane sulfonate are exa~-ples. Suitable zwitterionic surfactants include derivatives of aliphatic quaternary ammonium compounds with one aliphatic substituent containing 8 to 18 carbon atoms and another containing an anionic water-solubilizing group. Examples of are 3-(N,N-dimethyl-N-hexadecyla~monio)propane-1-sul-fonate and 3-(N,N-dimethyl-N-hexadecylammonio)-2-hydroxy propane-lsulfon-ate.

C. ~ULSIFIAB1E CONCENIRATES
Emulsifiable concentrates are solutions in which the active materials and an emulsifying agent are dissolved in a non-watermiscible solvent. Prior to use, the concentrate is diluted with ~ater to form a suspended emulsion of solvent droplets.

Typical solvents for use in emulsifiable 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 ~lkylol amide condensates, calcium and amine salts of fatty alcohol sulfates, oil-soluble petroleum sulfonates, or preferably mixtures of these emulsifying agents. ~uch emulsifying agents usually comprise about 1 to 10 weight percent of the total composition.

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 emulsifier. Other additives such as spreading agents and stickers can also be included.

D. WETT.4BLE POWDERS
~ ettable powders are ~ater-dispersible compositions contain-ing the active material, an inert solid extender, and one or more surfac-tants to provide rapid wetting and ~revent flocculation when suspended in water.

Suitable solid extenders include both natural minerals and materials derived synthetically frcm such minerals. Examples include kaolinites, attapulgite clay, montmorillonite clays, synthetic silicas, synthetic magnesium silicate and calcium sulfate dihydrate.

Suitable surfactants include both nonionic and anionic types, and function as wetting agents and dispersants. Usually one of each is included. Pre~erred 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, sul-fated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated vegetable oils, and ditertiary acetylenic glycols. Preferred dispersants are methyl cellulose, polyvinyl alcohol, lignin sulfonates, polymeric aIkylnaphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bisnaphthalenesulfonate, and sodium-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 disper-sant, 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 a~ anti~oaming agent.

E. IN GEME~AL
In general, any conventional postemergence method of applica-tion can be used, including common dusting or spraying equipment. Theamount 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. Herbi-cidal effects are usually achieved at 0.1 to 50 pounds active ingredient per acre, preferably l to 10, while plant growth regulation is usually ., 13 1~8~
achieved at 0.1 to 20 pounds active ingredient per acre, preferably 0.5 to 5. It will ~e readily apparent to one skilled in the art that com-pounds of lower activity will require a higher dosage than more active compounds for the same degree o~ control.

Claims (22)

WHAT IS CLAIMED IS:

1. A compound having the formula where R1, R2, and R3 represent C1-C6 alkyl, and n is zero or one, where-in no more than two of R1, R2 or R3 are identical.

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

3. The compound according to Claim 2 in which R1, R2 and R3 each represent C1-C4 alkyl.

4. The compound according to Claim 2 in which R1 and R2 are each n-butyl and R3 is methyl.

5. The compound according to Claim 2 in which R1 and R2 are each ethyl and R3 is methyl.

6. The compound according to Claim 2 in which R1 and R2 are each methyl and R3 is isopropyl.

7. The compound according to Claim 2 in which R1 and R2 are each methyl and R3 is n-butyl.

8. A method of controlling undesirable vegetation comprising applying to the vegetative in post-emergent state an herbicidal composi-tion comprising an herbicidally effective amount of a compound having the formula where R1, R2, and R3 represent C1-C6 alkyl, and n is zero or one, where-in no more than two of R1, R2 or R3 are identical, and an inert diluent carrier.

9. The method according to Claim 8 in which n is zero.

10. The method according to Claim 9 in which R1, R2 and R3 each represent C1-C4 alkyl.

11. The method according to Claim 9 in which R1 and R2 are each n-butyl and R3 is methyl.

12. The method according to Claim 9 in which R1 and R2 are each ethyl and R3 is methyl.

13. The method according to Claim 9 in which R1 and R2 are each methyl and R3 is isopropyl.

14. The method according to Claim 9 in which R1 and R2 are each methyl and R3 is n-butyl.

15. A method of controlling undesirable vegetation in the post-emergent state by applying to the vegetation a post-emergent herbi-cidally effective amount of a tri-mixed alkylsulfonium salt of N-phos-phonomethylglycine wherein said alkyl groups each contain from 1 to 6 carbon atoms and wherein no more than two of said alkyl groups are iden-tical.

16. The method of Claim 15 wherein said alkyl groups each con-tain 1 to 4 carbon atoms and no more than two of said alkyl groups are identical.

17. A method of controlling undesirable vegetation in the post-emergent state by applying to the vegetation a post-emergence herbi-cidally effective amount of a tri-mixed alkylsulfoxonium salt of N-phos-phonomethylglycine wherein said alkyl groups each contain from 1 to 6 carbon atoms and wherein no more than two of said alkyl groups are iden-tical.

18. The method of Claim 17 wherein said alkyl groups each con-tain 1 to 4 carbon atoms and no more than two of said alkyl groups are identical.

19. Compounds corresponding to tri-mixed alkylsulfonium salts of N-phosphonomethylglycine wherein said alkyl groups each contain from 1 to 6 carbon atoms and wherein no more than two of said alkyl groups are identical.

20. Compounds of Claim 19 wherein said alkyl groups each con-tain 1 to 4 carbon atoms and no more than two of said alkyl groups are identical.

21. Compounds corresponding to tri-mixed alkylsulfoxonium salt of N-phosphonomethylglycine wherein said alkyl groups each contain from 1 to 6 carbon atoms and wherein no more than two of said alkyl groups are identical.

22. Compunds of Claim 21 wherein said alkyl groups each con-tain 1 to 4 carbon atoms and no more than two of said alkyl groups are identical.