Alkylphosphonate Diesters of N-Phosphonomethylglycinate as Herbicides

This invention relates to diesters of N-phosphonomethylglycinate which are useful as herbicides. More particularly this invention relates to alkyl phosphonate diesters of N-phosphonomethylglycinate which are useful as herbicides and to herbicidal methods employing such compounds and compositions.

U.S. Pat. No. 4,025,331 issued to Jean-Pierre Leber on May 24, 1977 discloses N-phosphonomethylglycine derivatives of the formula ##STR1## wherein X is hydrogen, unsubstituted or substituted hydrocarbon or a cation and M is hydrogen or a cation. The compounds disclosed in U.S. Pat. No. 4,025,331 supra are said to possess herbicidal and plant growth regulating properties.

The compounds of the present invention are represented by the formula ##STR2## wherein R is lower alkyl; R.sub.1 is selected from the group consisting of hydrogen, lower alkyl and lower alkoxycarbonyl, R.sub.2 is selected from the group consisting of halogen, lower alkoxycarbonyl and a ##STR3## group wherein Z is lower alkyl; and n is an integer from 0 to 3.

As employed throughout the claims and description, the term "lower alkyl" includes alkyl radicals which have up to five carbon atoms in a straight or branched chain, for example, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl and t-butyl.

As employed throughout the claims and description, the term "lower alkoxy" includes groups of the aforedefined term "lower alkyl" which have one oxygen associated therewith such as methoxy, ethoxy, propoxy, butoxy and the like.

The term "lower alkoxy carbonyl" is employed throughout the claims and description to include groups representative of the aforedefined term "lower alkoxy" in combination with a carbonyl group. Suitable examples of "lower alkoxy carbonyl" groups include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl and the like.

In a preferred embodiment, R is preferably ethyl; n is 0 or 1; R.sub.1 is hydrogen, methyl or ethoxycarbonyl; and R.sub.2 is chloro, methoxycarbonyl, ethoxycarbonyl and ##STR4## wherein Z is preferably methyl.

In accordance with the present invention alkylphosphonate diesters of N-phosphonomethylglycinate of the formula ##STR5## may be prepared by simultaneously reacting a tri-substituted phosphite of the formula ##STR6## wherein R.sub.1 and R.sub.2 are defined as recited above with water and with 1,3,5-tri-(alkoxycarbonylmethyl) hexahydro-1,3,5-triazine (trimer of the Schiff's base of formaldehyde and alkyl glycinate) of the formula ##STR7## wherein R is as aforedefined to form a crude diester composition containing diester product. A purified phosphonate diester product may be recovered from the crude diester composition by employing suitable separation means as, for example, employing a chromatographic and/or distillation means having sufficient capability and capacity to effect the aforedescribed recovery.

The aforedescribed reaction is carried out at a temperature in the range from about 10 to 110 and preferably from about 20.degree. to about 100.degree. C.

In preparing phosphonate diester compounds of formula (I), the range of reactants is not narrowly critical. Preferably, however for each mole of trialkylphosphite employed, one should employ from about 0.5 to about 1.5 mole water, about 1/4 to about 1/2 mole 1,3,5-tri-(alkoxycarbonylmethyl)hexahydro-1,3,5-triazine (which is equivalent to 1 mole of the monomer of a Schiff's base of formaldehyde and the corresponding alkyl glycinate) while no catalyst is required for the aforedescribed reaction to proceed although a catalyst may be employed if desired.

The reaction time is in the range from about 1 to about 72 and is preferably from about 2 to about 50 hours.

While the process of this invention can be conducted at atmospheric, sub-atmospheric or super-atmospheric pressure, for convenience and economy it is generally preferred to conduct these processes at atmospheric pressure.

Although a suitable solvent may be employed in the aforedescribed process, it is preferred that the reaction be carried out in the absence of a solvent.

Suitable agitation is provided, preferably by stirring or otherwise agitating the reaction composition.

In practicing the aforedescribed process the aforedescribed reactants are admixed together although the reactants may be admixed in any order if desired to form a reaction composition.

In another embodiment of this invention the aforedescribed diester compounds of formula (I) may be prepared by reacting a disubstituted phosphite of the formula ##STR8## with the aforedescribed trimer of formula (III). Typically a coproduct alcohol compound formed when employing a triphosphite and water as reactants along with said trimer is not believed formed in this embodiment.

The ratio of reactants disubstituted phosphite and trimer, are not narrowly critical. Preferably, for each mole of diphosphite employed, one should employ about 1/4 to about 1/2 mole trimer of formula (III).

The aforedescribed conditions of pressure, agitation and admixing discussed with respect to use of tri-substituted phosphite, water and trimer apply generally with respect to this embodiment as well.

The temperature employed for this embodiment is generally in the range from about 90.degree. to about 110.degree. C. and the reaction time is generally in the range from about 1 to about 12 hours.

The following examples are presented to define the invention more completely without any intention of being limited thereby. All parts and percentages are by weight, unless otherwise specified.

A reaction composition comprising 15.0 g (0.0441 mole) tri(ethoxycarbonylmethyl)phosphite, 0.79 g (0.0441 mole) water and 5.08 g (0.0147 mole) 1,3,5-tri-(ethoxycarbonylmethyl) hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for three hours with agitation. An alcohol, ethyl glycolate, co-product was removed by bulb to bulb distillation of the reaction mixture at 75.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on microcrystalline cellulose with an eluent of ethyl acetate. The product, glycine, N-[bis(ethoxycarbonylmethoxy)phosphinylmethyl]-, ethyl ester was obtained as a viscous yellow oil in 62% yield (10.1 g) having the following analysis:

Calculated: C, 42.28; H, 6.55; N, 3.79; P, 8.39; Found: C, 42.35; H, 6.12; N, 3.90; P, 8.54.

A reaction composition comprising 19.9 g (0.033 mole) tri(1,2-diethoxycarbonylethyl)phosphite, 0.6 g (0.033 mole) water and 3.8 g (0.011 mole) 1,3,5-tri-(ethoxycarbonylmethyl) hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for 2.5 hours with agitation. An alcohol, diethyl malate (.alpha.-hydroxysuccinate), co-product was removed by bulb to bulb distillation of the reaction mixture at 75.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on silica gel with an eluent of ethyl acetate. The product, butanoic acid, 2,2'-[[[(2-ethoxy-2-oxo-ethyl)amino]methyl]phosphinylidene]bis(oxy)bis-, tetraethyl ester was obtained as a viscous yellow oil in 13% yield (2.4 g) having the following analysis:

Calculated: C, 46.58; H, 6.70; N, 2.59; P, 5.72; Found: C, 46.75; H, 6.60; N, 2.85; P, 6.03.

A reaction composition comprising 15.0 g (0.0353 mole) butanoic acid, 3,3',3",-phosphinidynetris(oxy)tris-, triethyl ester, 0.64 g (0.0353 mole) water and 5.08 g (0.0147 mole) 1,3,5-tri-(ethoxycarbonylmethyl) hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for three hours with agitation. An alcohol co-product ethyl .beta.-hydroxybutanoate was removed by bulb to bulb distillation of the reaction mixture at about 80.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on microcrystalline cellulose with an eluent of ethyl acetate. The product, butanoic acid, 3,3'-[[[[(2-ethoxy-2-oxoethyl]amino]methyl]phosphinylidene]bis-(oxy)]bis-, diethyl ester was obtained as a viscous yellow oil in 61.3% yield (9.2 g) having the following analysis:

Calculated: C, 48.00; H, 7.58; N, 3.29; P, 7.28; Found: C, 47.03; H, 7.48; N, 3.56; P, 8.07.

A reaction composition comprising 15.0 g (0.039 mole) tri-(1-ethoxycarbonylethyl)phosphite, 0.71 g (0.039 mole) water and 4.525 g (0.0131 mole) 1,3,5-tri-(ethoxycarbonylmethyl)hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for three hours with agitation. An alcohol co-product ethyl .alpha.-hydroxypropionate was removed by bulb to bulb distillation of the reaction mixture at 25.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on microcrystalline cellulose with an eluent of ethyl acetate. The product, propanoic acid, 2,2'-[[[[(2-ethoxy-2-oxoethyl)amino]methyl]phosphinylidene]bis(oxy)]-bis-, diethyl ester was obtained as a viscous yellow oil in 84.5% yield (13.1 g) having the following analysis:

Calculated: C, 45.34; H, 7.10; N, 3.53; P, 7.80; Found: C, 44.68; H, 6.69; N, 4.12; P, 8.56.

A reaction composition comprising 20.0 g (0.0742 mole) tri-(2-chloroethyl)phosphite, 1.34 g (0.0742 mole) water and 8.53 g (0.0247 mole) 1,3,5-tri-(ethoxycarbonylmethyl) hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for three hours with agitation. An alcohol co-product 2-chloroethanol was removed by bulb to bulb distillation of the reaction mixture at 25.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on microcrystalline cellulose with an eluent of ethyl acetate. The product, glycine, N-[[bis(2-chloroethoxy)phosphinyl]methyl]-, ethyl ester was obtained as a viscous yellow oil in 96.7% yield (23.1 g) having the following analysis:

Calculated: C, 33.56; H, 5.63; N, 4.35; P, 9.62; Found: C, 32.94; H, 5.65; N, 4.06; P, 9.51.

A reaction composition comprising 15.0 g (0.0441 mole) tri-(1-methoxycarbonylethyl)phosphite, 0.79 g (0.0441 mole) water and 5.08 g (0.0147 mole) 1,3,5-tri-(ethoxycarbonylmethyl)hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for three hours with agitation. An alcohol co-product methyl .alpha.-hydroxypropionate was removed by bulb to bulb distillation of the reaction mixture at 75.degree. C. and 0.1 mmHg. The distillation residue was chromatographed on microcrystalline cellulose with an eluent of ethyl acetate. The product, propanoic acid, 2,2'-[[(ethoxycarbonylmethyl)amino]methylphosphinylidenedioxy]]bis-, dimethyl ester was obtained as a viscous yellow oil in 73.6% yield (9.2 g) having the following analysis:

Calculated: C, 42.28; H, 6.55; N, 3.79; P, 8.39; Found: C, 41.92; H, 6.23; N, 3.61; P, 7.74.

A reaction composition comprising 5.46 g (0.0215 mole) di-(2-acetyloxyethyl)phosphite and 2.48 g (0.0072 mole) 1,3,5-tri-(ethoxycarbonylmethyl)hexahydro-1,3,5-triazine was heated to about 100.degree.-110.degree. C. for five hours with agitation. The reaction mixture was diluted with 25 ml of ethyl acetate and the purified compound was obtained by chromatography of this solution on silica gel with an eluent of ethyl acetate. The product, glycine, N-[[bis[2-acetyloxyethoxy]phosphinyl]methyl]-, ethyl ester was obtained as a viscous yellow oil in 42.8% yield (3.4 g) having the following analysis:

Calculated: C, 42.28; H, 6.55; N, 3.79; P, 8.39; Found: C, 42.14; H, 6.70; N, 3.63; P, 7.89.

The post-emergent herbicidal activity of some of the various compounds of this invention was demonstrated by greenhouse testing in the following manner. A good grade of top soil is placed in aluminum pans having holes in the bottom and compacted to a depth of 0.95 to 1.27 cm. from the top of the pan. A predetermined number of seeds of each of several dicotyledonous and monocotyledonous annual plant species and/or vegetative propagules for the perennial plant species were placed on the soil and pressed into the soil surface. The seeds and/or vegetative propagules are covered with soil and leveled. The pans are then placed on a sand bench in the greenhouse and watered from below as needed. After the plants reach the desired age (two to three weeks), each pan except for the control pans is removed individually to a spraying chamber and sprayed by means of an atomizer operating at a positive air pressure of approximately 1.46 kg/cm.sup.2 absolute. The atomizer contains 6 ml. of a solution or suspension of the chemical. In that 6 ml., is an amount of a cyclohexanone emulsifying agent mixture to give a spray solution or suspension which contains about 0.4% by weight of the emulsifier. The spray solution or suspension contains a sufficient amount of the candidate chemical in order to give application rates corresponding to those set forth in the tables. The spray solution is prepared by taking an aliquot of a 1.0% by weight stock solution or suspension of the candidate chemical in an organic solvent such as acetone or tetrahydrofuran or in water. The emulsifying agent employed is a mixture comprising 35 weight percent butylamine dodecylbenzene sulfonate and 65 weight percent of a tall oil ethylene oxide condensate having about 11 moles of ethylene oxide per mole of tall oil. The pans are returned to the greenhouse and watered as before and the injury to the plants as compared to the control is observed at approximately two and four weeks as indicated in the tables under WAT and the results recorded. In some instances, the two-week observations are omitted.

The post-emergent herbicidal activity index used in Tables I and II is as follows:

The plant species utilized in these tests are identified by letter in accordance with the following legend:

From the test results presented in Tables I and II, it can be seen that the post-emergent herbicidal activity of the compounds of this invention is, for the most part, general in nature. In certain specific instances, however, some selectivity is demonstrated. In this regard it should be recognized that each individual species selected for the above tests is a representative member of a recognized family of plant species.

The herbicidal compositions, including concentrates which require dilution prior to application to the plants, of this invention contain from 5 to 95 parts by weight of at least one compound of this invention and from 5 to 95 parts by weight of an adjuvant in liquid or solid form, for example, from about 0.25 to 25 parts by weight of wetting agent, from about 0.25 to 25 parts by weight of a dispersant and from 4.5 to about 94.5 parts by weight of inert liquid extender, e.g., water, acetone, tetrahydrofuran, all parts being by weight of the total composition. Preferably, the compositions of this invention contain from 5 to 75 parts by weight of at least one compound of this invention, together with the adjuvants. Where required, from about 0.1 to 2.0 parts by weight of the inert liquid extender can be replaced by a corrosion inhibitor such as ethanol mercaptan, sodium thiosulfate, dodecylmono or dimercaptan or anti-foaming agent such as a dimethylpolysiloxane, or both. The compositions are prepared by admixing the active ingredient with an adjuvant including diluents, extenders, carriers and conditioning agents to provide compositions in the form of finely-divided particulate solids, pellets, solutions, dispersions or emulsions. Thus, the active ingredient can be used with an adjuvant such as a finely-divided solid, a liquid of organic origin, water, a wetting agent, a dispersing agent, an emulsifying agent or any suitable combination of these.

The herbicidal compositions of this invention, particularly liquids and soluble powders, preferably contain as a conditioning agent one or more surface-active agents in amounts sufficient to render a given composition readily dispersible in water or in oil. The incorporation of a surface-active agent into the compositions greatly enhances their efficacy. By the term "surface-active agent", it is understood that wetting agents, dispersing agents, suspending agents and emulsifying agents are included therein. Anionic, cationic and nonionic agents can be used with equal facility.

Preferred wetting agents are alkyl benzene and alkyl naphthalene 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, polyoxyethylene derivatives of phenols and alkylphenols (particularly isooctylphenol and nonylphenol) and polyoxyethylene derivatives of the mono-higher fatty acid esters of hexitol anhydrides (e.g., sorbitan). Preferred dispersants are methyl cellulose, polyvinyl alcohol, sodium lignin, sulfonates, polymeric alkyl naphthalene sulfonates, sodium naphthalene sulfonate, polymethylene bisnaphthalenesulfonate and sodium N-methyl-N-(long chain acid) taurates.

The following list gives some specific herbicidal compositions of this invention. It is to be realized that the solvents and surfactants are interchangeable in the composition.

When operating in accordance with the present invention, effective amounts of the compounds or compositions of this invention are applied to the plants, or to soil containing the plants, or are incorporated into aquatic media in any convenient fashion. The application of liquid and particulate solid compositions to plants or soil can be carried out by conventional methods, e.g., power dusters, boom and hand sprayers and spray dusters. The compositions can also be applied from airplanes as a dust or a spray because of their effectiveness at low dosages. The application of herbicidal compositions to aquatic plants is usually carried out by adding the compositions to the aquatic media in the area where control of the aquatic plants is desired.

The application of an effective amount of the compounds or compositions of this invention to the plant is essential and critical for the practice of the present invention. The exact amount of active ingredient to be employed is dependent upon the response desired in the plant as well as such other factors as the plant species and stage of development thereof, and the amount of rainfall as well as the specific glycine employed. In foliar treatment for the control of vegetative growth, the active ingredients are applied in amounts from about 0.112 to about 56.0 or more kilograms per hectare. In pre-emergent treatments, the rate of application can be from about 0.56 to about 22.4 or more kilograms per hectare. In applications for the control of aquatic plants, the active ingredients are applied in amounts of from about 0.01 parts per million to about 1000 parts per million, based on the aquatic medium. An effective amount for phytotoxic or herbicidal control is that amount necessary for overall or selective control, i.e., a phytotoxic or herbicidal amount. It is believed that one skilled in the art can readily determine from the teachings of this specification, including examples, the approximate application rate.

There are several methods for applying liquid compositions of this invention to emerged plants. Such methods include the use of wiper systems whereby the plant to be treated is contacted with an absorbent material containing the particular liquid composition, a portion of which is thereby released onto the plant upon contact therewith. Such wiper systems typically comprise a reservoir of the liquid composition into which a portion of the absorbent material is placed and is fed therethrough. Generally, substances employable as absorbent material include substances of any shape or form capable of absorbing the liquid composition and releasing a portion of the same upon contact with the plant. Typical absorbent materials include felt, foam rubber, cellulose, nylon, sponges, hemp, cotton, burlap, polyester over acrylic, combinations thereof and the like. Forms of absorbent material include rope, twine, string, cloths, carpets, combinations thereof and the like. These forms may be assembled in any manner desired including a pipe rope wick, a wedge rope wick, a multi-rope wick and the like.

In another application method, liquid compositions may be selectively applied to weeds by the use of recirculating sprayer systems wherein the recirculating spray unit is mounted on a tractor or high clearance mobile equipment and the spray is directed horizontally onto the weeds growing over a crop. Spray not intercepted by the weeds is collected in a recovery chamber before contacting the crop and is reused. Roller applications may also be employed to apply liquid compositions to weeds growing over a crop.

In yet another application method, shielded applicators may be employed to direct the liquid composition in the form of a spray onto the weeds while effectively shielding the crops from the spray.

These and other application methods for selectively applying liquid compositions to weeds are discussed in detail in Innovative Methods of Post-Emergence Weed Control, McWhorter C. G, Southern Weed Science Society, 33rd Annual Meeting Proceedings, Jan. 15-17, 1980; Auburn University Printing Service, Auburn, Ala. U.S.A., the teachings of which are incorporated herein by reference in their entirety.

Another method of applying liquid compositions of this invention to plants includes controlled droplet application which is also known as the ultra low-volume chemical application. Controlled droplet application involves the production of uniform or nearly uniform spray drops of a predetermined size and the conveyance of these drops with negligible evaporation to a spray target. In particular, this method comprises feeding spray solutions to a rotary atomizer comprising a small disk with serrated edges that disperses liquid into droplets as the disk spins. Different droplet sizes are produced by changing solution flow rates to the spinning disk or changing the speed of rotation of the disk.

The aforementioned and other methods for applying liquid compositions to plants are discussed in detail in "Rope Wick Applicator--Tool With A Future", Dale, James E., pp. 3-4, "The Recirculating Sprayer and Roundup.RTM. Herbicide", Derting, Claude W., pp. 5-7, and "C.D.A. Herbicide Application", McGarvey, Frank X., Weeds Today, Volume 11, Number 2, pp. 8-9, Late Spring, 1980, 309 W. Clark St., Champaign, Ill., the teachings of which are incorporated herein by reference in their entirety.

Although this invention has been described with respect to specific modifications, the details thereof are not to be construed as limitations, for it will be apparent that various equivalents, changes and modifications may be resorted to without departing from the spirit and scope thereof and it is understood that such equivalent embodiments are intended to be included herein.