This invention relates to alkyl N-heterocyclic-N'-(arylsulfonyl)carbamimidothioates having agricultural activity. It relates also to such compounds wherein the aryl radical has been replaced by a thienyl radical.

In our United States Patent Specification No. 4,127,405 We have disclosed, inter alia, compounds of the following formula as herbicides:

In the former R is:

and in the latter, R is

In each of those applications R₁ may be

U.S. Patent 3,823,007 discloses isourea salts as herbicides:

• wherein R is chloro, bromo,'iodo, cyano, alkyl, alkoxy, nitro, amino or -

• _R³ is hydrogen or alkyl;
• n is the integer one to three;
• m is the integer one or two;
• M is of alkali metal, alkaline earth metal or ammonium;
• _R¹ and _R² are each independently hydrogen, alkyl, alkoxy, alkynyl, phenyl, substituted phenyl having a maximum of three substituents said substituents being alkyl bromine, chlorine, alkoxy, phenoxy, mono and dihalogenated phenoxy said halogen being chlorine or bromine, or the group

  and

• _R⁴ and _R⁵ are each independently hydrogen or alkyl.

U.S. Patent 3,714,209 discloses the iso- propylidineaminoethanol salt of p-nitrobenzenesul- fonylisourea as a herbicide:

• R₂ is C₁-C₁₀ alkyl; CH₂CH₂OCH₃; CH₂CH₂OCH₂CH₃;-CH₂CH₂CH₂OCH₃; CH₂A,

• where A is CO₂-C₁-C₄ alkyl;

  phenyl; phenyl substituted with CH₃ or chlorine; CN; C₂-C₄ alkenyl; C₂-C₄ alkynyl;

• R₃ is H, Cl, Br, CH₃, CH₃O, NO₂, CF₃, CH₃S(O)_n, COOR₅, or CONR₆R₇;
• R₄ is H, F, Cl, Br, CH₃, CH₃0, NO₂, CF₃, or CH₃S(O)_n; wherein n = 0, 1 or 2;
• R₅ is C₁-C₄ alkyl or C₃-C₄ alkenyl;
• R₆ is H, CH₃0 or C₁-C₃ alkyl;
• R₇ is H or C₁-C₃ alkyl;
• X is CH₃, CH₃0, CH₃CH₂O or CH₃OCH₂;
• Y is CH₃ or CH₃O; and
• Z is CH or N; provided that R₃ and R₄ differ from one another when either of them is NO₂ or CF₃; and
• that when R₆ is CH₃0, R₇ is CH₃.

Preferred for their high activity and/or favorable cost are those compounds of Formula I wherein independently or in any combination

• A) The generic scope I where R₁ is

• B) Compounds of A where R₃ is Cl, Br, CH₃, CH₃O, NO₂ or CO₂R₅ and R₄ is H or Cl.

Specifically preferred for their outstanding activity and/or highly favorable cost are (melting points in °C):

• methyl N'-(2, 5-dimethoxyphenylsulfonyl)-N-(4,6-dimethoxypyrimidin-2-yl[carbamimidothioate, m.p. 207-208,
• methyl N'-(2-chlorophenylsulfonyl)-N-(4,6-dimethoxypyrimidin-2-yl)carbamimidothioate, m.p. 169-171;
• methyl N'-(2-chlorophenylsulfonyl)-N-(4-methoxy-6-methylpyrimidin-2-yl)carbamimidothioate, m.p. 160-162;
• methyl N'-(2-chlorophenylsulfonyl[-N-(4,6-dimethoxy-1,3,5-triazine-2-yl)carbamimido- thioate.
• methyl N'-(2-chlorophenylsulfonyl)-N-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)carbamimidothio- ate, m.p. 148-150°;
• methyl 2-[(2-chlorophenylsulfonylimino)(4-methoxy-6-methylpyrimidin-2-ylamino)methylthio]-propionate, m.p. 166-168°.

Synthesis

As shown in Equation 1, the compounds of Formula I can be prepared by reacting an appropriately substituted carbamimidothioic acid salt of Formula II with an alkylating agent of Formula III:

Equation I:

add the isothiocyanate to a stirred suspension of the aminohettrocycle. Since such isothiocyanates usually are liquids, their addition is more easily controlled. Catalysts, such as l,4-diazabicyclo[2.2.2]octane or dibutyltindilaurate, maybe used.

In some cases, sulfonylthioureas of Formula IV are more conveniently prepared, as shown in Equation 3, by reacting an appropriately substituted sulfonamide of Formula VII with the appropriate 2-isothiocyanatoheterocycle of Formula VIII; R₁, X, Y and Z being as previously defined:

The preparation of 2-isothiocyanatohetero- cycles VIII is taught in Japanese patent Kokai 51-143686.

The preparation of the sulfonyl thioureas IV and reactants therefor is described in said United Patent Specification No. 4,127,405, the contents of which in that connection are incorporated herein by reference.

The compounds of Formula I may also be prepared as shown in Equation 4. This is the preferred procedure for Z = N.

Equation 4

reaction mixture was refluxed for 0.5 hour, whereupon 5.5 g of Methyl iodide in 10 ml of anhydrous tetrahydrofuran was added. After refluxing for an additional 4 hours the reaction mixture was cooled, solvent was removed under vacuum, and the residue recrystallized from acetonitrile to afford 6.5 g of methyl N'-(2-chlorophenylsulfonyl)-N-(4,6-dimethoxy- pyrimidin-2-yl)carbamimidothioate, m.p. 169-171°C.

EXAMPLE 3

Methyl N'-(2-chlorophenylsulfonyl)-N-(4-methoxy-6-methylpyrimidin-2-yl)carbamimidothioate

To a suspension of 11.2 g of N-[4-methoxy-6-methylpyrimidin-2-yl)aminothioxomethyl]-2-chloro- benzenesulfonamide in 150 ml of anhydrous tetrahydro-' furan was added 13.0 ml of 3M NaOCH₃/MeOH solution. The reaction mixture was refluxed for 0.5 hour, whereupon 5.5 g of methyl iodide in 10 ml of anhydrous tetrahydrofuran was added. After refluxing for an additional 4 hours, the reaction mixture was cooled, solvent was removed under vacuum and the residue was recrystallized from acetonitrile to afford 8.6 g of methyl N'(2-chlorophenylsulfonyl)-N-(4-methoxy-6-methylpyrimidin-2-yl)carbamimidothioate, m.p. 160-162°C.

EXAMPLE 4

Methyl N' (2,5-dimethoxyphenylsulfonyl)-N-(4-methoxy-6-methyl-1,3,5-triazine-2-yl)carbonimidothioate

1.4 grams of 2-amino-4-methoxy-6-methyltriazine was dissolved in a mixture of 20 ml of tetrahydrofuran and 60 ml of dimethylformamide. 0.48 grams of sodium-hydride (50% mineral oil dispersion) was added. The reaction was stirred until hydrogen evolution ceased. 2.75 grams of N(2,5-dimethoxyphenylsulfonyl)-carbonimidodithoic acid, S,S-dimethyl ester was added all at once. The reaction mixture was stirred 24 hours at ambient temperature. The mixture was poured into 300 ml of water and acidified to a pH of 5 with 20% hydrochloric acid. The mixture was filtered. The crude solid obtained was crystallized from ethyl acetate to yield 1.1 grams of product with m.p. 168-169°.

Using the procedures of Examples 1-3 with equivalent amounts of appropriate N-(triazinylamino- thioxomethyl)benzenesulfonamides (or thiophenesulfon- amides), metal compounds and alkylating agents, the compounds of Tables III and IV can be prepared.

Formulations

Useful formulations of the compounds of Formula I can be prepared in conventional ways, They include dusts,' granules, pellets, solutions, suspensions, emulsions, wettable powders, emulsifiable concentrates and the like. Many such formulations may be applied directly. Sprayable formulations can be extended in suitable media and used at spray volumes of from a few liters to several hundred liters per hectare. High strength compositions are primarily used as intermediates for further formulation. The formulations, broadly, contain about 0.1% to 99% by weight of active ingredient(s) and at least one of a) about 0.1% to 20% surfactant(s) or b) about 1% to 99.9% solid or liquid diluent(s). More specifically, they will contain these ingredients in the approximate proportions set forth in Table VII.

Lower or higher levels of active ingredient can be present depending upon the intended use and the physical properties of the compound. Higher ratios of surfactant to active ingredient are sometimes desirable, and are achieved by incorporation into the formulation or by tank mixing.

19 and Examples 10 through 41.

R. W. Luckenbaugh, U.S. Patent 3,309,192, March 14, 1967, Col. 5, line 43 through Col. 7, line 62 and Examples 8, 12, 15, 39, 41, 52, 53, 58, 132, 138-140, 162-164, 166, 167, 169-182.

H. Gysin and E. Knusli, U.S. Patent 2,891,855, June 23, 1959, Col. 3, line 66 through Col..5, line 17 and Examples 1-4.

G. C. Klingman, "Weed Control as a Science", John Wiley & Sons, Inc., New York, 1961, pp. 81-96.

J. D. Fryer and S. A. Evans, "Weed Control Handbook", 5th Ed., Blackwell Scientific Publications, Oxford, 1968, pp. 101-103.

In the following examples, all parts are by weight unless otherwise indicated.

EXAMPLE 4

. The ingredients are blended, hammer-milled until almost all of the solid particles thereof are under 50 microns in size, and then the ingredients are reblended.

EXAMPLE 5

The ingredients are blended, coarsely hammermilled and then air-milled to produce particles resulting suspension may be applied directly, but preferably after being extended with oils or emulsi- fied in water.

EXAMPLE 9

The ingredients are thoroughly blenied. After grinding in a hammer-mill to produce particles almost all of which are below 100 microns in size, the material is reblended and sifted through a U.S.S. No. 50 sieve (0.3 mm opening) and packaged.

EXAMPLE 10

The active ingredient is dissolved in the solvent and the solution is sprayed upon dedusted attapulgite granules in a double cone blender. After spraying of the solution has been completed, the blender is allowed to run for a short period and then the granules are packaged.

EXAMPLE 14

The ingredients are blended and ground in a hammer-mill to produce a material almost all of which passes a U.S.S. No. 50 screen (0.3 mm opening). The concentrate may be formulated further if necessary.

EXAMPLE 15

The ingredients are blended and ground in a hammer-mill to produce particles almost all of which are below 100 microns in size. The material is sifted through a U.S.S. No. 50 screen and then packaged..

EXAMPLE 16

The ingredients are thoroughly blended, coarsely hammer-milled and then air-milled to produce particles almost all of which are below 10 microns in size. The material is reblended and then packaged. sand mil until the solid particles have been reduced to under about 5 microns in size. The resulting suspension may be applied directly, but preferably after being extended with oils or emulsified in water.

EXAMPLE 20

The ingredients are blended and ground together in a sand mill to produce particles almost all of which are under 5 microns in size.

EXAMPLE 21

The active ingredient is dissolved in a solvent and the solution is sprayed upon dedusted attapulgite granules in a.double-cone blender. After spraying of the solution has been completed, the material is warmed to evaporate the solvent. The material is allowed to cool and then packaged.

UTILITY

The compounds of the present invention are useful as herbicides. They may be applied either pre- or post-emergence for selective weed control in crops or for the control of undesired vegetation in noncrop areas, such as weeds and brush growing on ester, dthyl-N-benzoyl-N-(3,4-dichlorophenyl)-2-aminopropionate, l,2-dimethyl-3,5-diphenylpyrazol- ium methylsulfate, methyl 2-[4-(2,4-dichlorophen- oxy)-phenoxy]propanoate, 4-amino-6-tert-butyl-3-(methylthio)-1,2,4-triazin-5(4H)-one, 3-(3,4-dichlorophenyl)-1-methoxy-1-methylurea, 3-isopropyl-1H-2,1,3-benzothiodiazin-(4)-3H-one 2,2-dioxide, α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine, 1,1'-dimethyl-4,4'-bipyridinium ion, monosodium methanearsonate, 2-chloro-2',6'-diethyl(methoxymethyl)acetanilide, and l,l-dimethyl-3-(a,a,a-trifluoro-m-tolyl)-urea.

The activity of these compounds was dis- . covered in greenhouse tests. The tests are described and the data resulting from them are shown below.

Ratings for compounds tested by Procedure A through C described hereinbelow are:

• 0 = no effect
• & or 10 = maximum effect
• B = burn
• C = chlorosis or necrosis
• D = defoliation
• E = emergence inhibition
• G = growth retardation
• H = formative effects
• U = unusual pigmentation
• 6F = delayed flowering

TEST PROCEDURE A

Seeds of crabgrass (Digitaria spp.), barn- yardgrass (Echinochloa crusgalli), wild oats (Avena fatua), cassia (Cassia tora), morningglory (Ipomoea spp.), cocklebur (Xanthium spp.), sorghum, corn, soybean, rice, wheat and nutsedge tubers (Cyperus rotundus) were planted in a growth medium and treated preemergence with a nonphytotoxic solvent solution of the compounds set forth in Table VIII.