WO1994018173A1

WO1994018173A1 - Benzimidazolesulfonic acid derivatives as microbicides

Info

Publication number: WO1994018173A1
Application number: PCT/EP1994/000187
Authority: WO
Inventors: Urs Müller; Marius Sutter; Adolf Hubele
Original assignee: Ciba-Geigy Ag
Priority date: 1993-02-05
Filing date: 1994-01-25
Publication date: 1994-08-18
Also published as: AU5999094A; ZA94774B; TW242556B; IL108545A0; MX9400901A

Abstract

Benzimidazolesulfonic acid derivatives of formula (I), wherein R1 is halogen which may be identical or different, C1-C3alkyl, C1-C3alkoxy or C1-C3haloalkyl; R2 is cyano, CSNH2 or -C(SR')=NH, where R' is C1-C4alkyl; R3 is C1-C4alkyl or N(R')(R''), where R' and R'' are C1-C3alkyl which may be identical or different; and X is oxygen or sulfur, and n is 0, 1 or 2, are valuable microbicides. They can be used in plant protection in the form of suitable compositions, inter alia for controlling fungal diseases.

Description

BENZIMIDAZOLESULFONIC ACID DERIVATIVES AS MICROBICIDES

The present invention relates to novel benzimidazolesulfonic acid derivatives of formula I below. The invention also relates to the preparation of these substances and to agrochemi- cal compositions comprising at least one of said compounds as active ingredient. The invention further relates to the preparation of said compositions and to the use of the novel microbicides or compositions for controlling or preventing the infestation of plants by phytopathogenic microorganisms, especially fungi.

The compounds of this invention have the general formula I

wherein the R₃SO₂ group is in 1- or 3-position and, in relation to the two substituents F₂HC-X- and Rj, forms pure or mixed position isomers, and wherein the substituents have the following meanings:

Ri is halogen which may be the same or different, C₁-C₃alkyl, C_rC₃alkoxy and

C_rC₃haloalkyl

R₂ is cyano, CSNH₂ or -C(SR')=NH, where R' = C_rC₄alkyl;

R₃ is C_rC₄alkyl or N(R")(R"'), where R" and R"' are C_rC₃al yl which may be the same or different;

X is oxygen or sulfur, and n is 0, 1 or 2.

Depending on the indicated number of carbon atoms, al yl by itself or as moiety of another substituent such as haloalkyl or alkoxy will typically be taken to mean the following straight-chain or branched groups: methyl, ethyl, propyl, butyl and the isomers thereof, including isopropyl, isobutyl, sec-butyl, tert-butyl. Halogen and halo denote fluoro, chloro, bromo or iodo. Haloalkyl thus denotes a monohalogenated to perhalogenated alkyl radical, typically CH₂F, CHF₂, CHFCH₃, CH₂CH₂Br, CF₂CHFC1 and the like.

The compounds of formula I are oils or solids that are stable at room temperature and which have valuable microbicidal properties. They may be used in agriculture or related fields for the preventive or curative control of microorganisms which are injurious to plants. When applied in low concentrations, the novel microbicides of formula I not only have an excellent microbicidal, especially fungicidal, activity, but are also particularly well tolerated by plants.

Within the scope of formula I, important compounds are those wherein Rj is halogen, C_rC₃alkyl, C_rC₃alkoxy or CF₃, R₃ is C_j^alkyl or N(CH₃)₂, and X is sulfur [subgroup lb].

Another important group of compounds falling within the scope of formula I embraces those compounds wherein R_t is halogen, C_rC₃alkyl, C C^lkoxy or CF₃, R₃ is C_rC alkyl or N(CH₃)₂, and X is oxygen [subgroup Ic].

Other important compounds falling within the scope of formula I are those wherein R_j, R₃, n and X have the given meanings and R₂ is CSNH₂ [subgroup Id].

Yet another important subgroup of compounds falling within the scope of formula I embraces those compounds wherein R_1?R₃, n and X have the given meanings and R₂ is CN [subgroup Ie].

Exemplary preferred individual compounds are; l(3)-(dimethylaminosulfonyl)-2-cyano-5-chloro-6-difluoromethoxybenzimidazole (compound 1.5), l(3)-(dimethylaminosulfonyl)-2-thioamido-5-chloro-6-difluoromethoxybenzimidazole (compound 1.6), l(3)-(dimethylaminosulfonyl)-2-cyano-6-difluoromethoxybenzimidazole (compound 1.2), l(3)-(dimethylaminosulfonyl)-2-cyano-4-bromo-6-difluoromethoxybenzimidazole (compound 1.4), l(3)-(methylsulfonyl)-2-cyano-4-bromo-6-difluoromethoxybenzimidazole (compound 1.3), l(3)-(dimethylaminosulfonyl)-2-cyano-4-bromo-6-difluoromethylthiobenzimidazole (compound 1J5), l(3)-(dimethylaminosulfonyl)-2-cyano-5-trifluoromethyl-6-difluoromethoxybenzimida- zole (compound 1J7), l(3)-(dimethylaminosulfonyl)-2-thioamido-5-trifluoromethyl-6-difluoromethoxybenz- imidazole (compound 1.18), l(3)-(dimethylaminosulfonyl)-2-cyano-6-difluoromethylthiobenzimidazole (compound 1.33), l(3)-(dimethylaminosulfonyl)-2-thioamido-5-chloro-6-difluoromethylthiobenzimidazole (compound 1.40).

The compounds of formula I can be prepared by reacting a compound of formula π

with a compound of formula m

Q-SO₂-R₃ ( )

wherein R_1? R₂, R₃, X and n are as defined for formula I, and M is hydrogen or an alkaline earth metal or alkali metal, preferably Na, K or Li, and Q is a halogen atom, preferably a chlorine or bromine atom, or is the radical O-SO₂-R₃, in an inert solvent and in the absence or presence of a base, in the temperature range from -30° to +180°C, preferably from -10° to 80°C, under normal pressure, reduced pressure or elevated pressure, preferably under normal presure.

Particularly suitable solvents are polar reaction media such as ketones alone (e.g. acetone, methyl ethyl ketone, tert-butyl methyl ketone) or in mixtures with ethers (e.g. diethyl ether, dioxane, tetrahydrofuran, 1,2-dimethoxyethane) or conveniently with dimethyl formamide or dimethyl sulfoxide. The benzimidazole derivative II is preferably reacted in the presence of a strong inorganic base (e.g. KOH, NaOH). Organic bases such as triethylamine may also be very suitably used.

The reactivity of the thioamide group [R₂ = -CSNH₂] or of the substituted isothioamide group [R₂ = -C(-SR')=NH] makes it advisable to employ a procedure in which these groups are introduced in the last reaction step after the sulfonylation. In this case, therefore, the sulfonylated 2-cyanobenzimidazole of formula I'

will subsequently be reacted with either H₂S or HS-R', where R' is as defined for formula I. The reaction giving the thioamide [R₂ = -CSNHJ is carried out in a polar solvent (e.g. an alcohol such as ethanol), but preferably in dimethyl formamide (DMF) or in an ether (e.g. diethyl ether, tetrahydrofuran) or acetonitrile, or in pyridine using a tertiary amine such as a trialkylamine. The introduction of H₂S is made at -20° to +80°C, preferably from -10° to +40°C.

A suitable procedure for preparing the substituted isothioamide group can be to treat the sulfonylated 2-cyanobenzimidazole of formula I' in a polar aprotic solvent (e.g. acetonitrile) in the presence of a weak base (e.g. an alkali metal carbonate) at -20° to +100°C, preferably from -10° to +40°C, with the thiol HS-R'.

It is preferred, however, to react the thioamide (formula I, R₂ = CSNH₂) with the corresponding alkyl halide in an inert solvent (e.g. chloroform, methylene chloride, diethyl ether, acetonitrile, etc.) without or with a base in the temperature range from 0°C to 100°C.

2-Cyanobenzimidazole derivatives of formula II are prepared by methods which are known per se from o-phenylenediamine derivatives or their salts:

(Y = anion of an acid; Hal = halogen, preferably Cl)

HY is an acid, preferably a mineral acid such as a hydrohalic acid or sulfuric acid. The o-phenylenediamine derivative can, however, also be used as free base if reaction step a) is carried out in glacial acetic acid. Preferred solvents are glacial acetic acid; ethers such as diethyl ether, dioxane, 1,2-dimethoxyethane; esters such as ethyl acetate; or alcohols such as methanol and ethanol.

The trihaloimidate (e.g. methyl trichloro- or chlorodifluoromethyl imidate) is conveniently added at -20°C to +100°C to a solution or suspension of the o-phenylenediamine derivative. In reaction step b), the 2-trihalomethylbenzimidazole derivative is preferably added to a concentrated aqueous ammonia solution (US-A-3 576 818).

The preparation of the 2-cyanobenzimidazole derivatives of formula II can also be carried out with the following o-nitroaniline derivative instead of the o-phenylenediamine derivative by reaction with formaldehyde and KCN in glacial acetic acid, with the addition of zinc chloride (or another Lewis acid) as catalyst, giving compounds of formula VIII

[K. Dimroth et al., Ber. 98, 3902 (1965)], which compounds are cyclised with K₂CO₃ to l-hydroxy-2-cyanobenzimidazole derivates [B. Serafinowa et al. Rocz. Chem. 5_i, 1783 (1977)] and can be reacted with PC1₃ to give compounds of formula π (M = hydrogen; R₂ = CN).

The intermediates of formula II, in which R₂ = CN and M = hydrogen, are novel and constitute a further object of this invention (compound group II'):

wherein R_:, X and n are as defined for formula I. Compounds of formula IV can be prepared by reduction of nitro group-containing compounds of formula DC. The classical reducing agents such as iron (Bechamps reduction), tin(II) chloride or hydrogen with a catalyst, typically Raney nickel or palladium/carbon, can be used as reducing agent. The reaction conditions are in accordance with those described in the literature (e.g. Houben- Weyl "Methoden der organischen Chemie").

The starting materials of formula

are prepared by reacting

HX

NO,

(V)

NH,

(Rι) n

with F₂CH-halogeno compounds, preferably with CHF₂C1 (Freon 22) under basic conditions and by further reaction according to reaction scheme c). Suitable bases are alkali metal or alkaline earth metal hydroxides, tert-ammonium bases, alkali metal or alkaline earth metal hydrides or alcoholates. It is preferred to use sind alkali metal hydroxides as aqueous solutions or in solid form.

The solvents employed may be ethers, preferably dioxane and tetrahydrofuran, alcohols and other common solvents.

The procedure will usually be in accordance with the following general reaction scheme c):

If R^s halogen, this substituent can also be introduced in a later step by posthalogenation in accordance with known methods.

The formation of the benzimidazoles from the 1,2-diaminoaryl compounds is a generally known reaction.

The reaction with difluorohalomethane compounds may also be carried out in the diamino or benzimidazole step. 2-Cyanobenzimidazolesulfonic acid derivatives of different structure are known fungicides and are disclosed, inter alia, in EP-A-487 286, JP-4-308 580, EP-A-517 476 and EP-A-239 508.

Surprisingly, it has now been found that the introduction of the novel structural unit F₂CHX- in conjunction with the other substituents leads to compounds that, for practical purposes, have an exceedlingly advantageous biocidal spectrum for controlling phytopathogenic microorganisms, especially fungi. Such compounds have very useful curative and preventive properties and are used for for protecting numerous cultivated plants. The compounds of formula I can be used to inhibit or destroy pests which occur on plants or parts of plants (fruit, blossoms, leaves, stems, tubers, roots) in different crops of useful plants, while at the same time the parts of plants that grow later are also protected from attack by phytopathogenic fungi.

The novel compounds of formula I prove effective against particular species of the phytopathogenic fungi belonging to the following classes: Fungi imperfecti, Basidiomycetes and Ascomycetes and especially against Oomycetes (e.g. Plasmopara, Pernospora, Pythium and Phytophthora). Thus the compounds of formula I are a useful addition to the microbicides suitable for controlling phytopathogenic fungi. The compounds of formula I can also be used as dressing agents for protecting seeds (fruit, tubers, grains) and plant cuttings against fungus infections as well as against phytopathogenic fungi which occur in the soil.

The invention also relates to compositions which comprise the compounds of formula I as active components, preferably to plant-protective compositions and to the use thereof in agriculture or related fields.

The invention also relates to the preparation of these compositions, which comprises intimately mixing the active ingredient with one or more than one substance or group of substances as described herein. The invention further relates to a method of treating plants, which comprises applying thereto the novel compounds of formula I or the novel compositions comprising them.

Target crops to be protected within the scope of the present invention typically comprise the following species of plants: cereals (wheat, barley, rye, oats, rice, maize, sorghum and related species), beet (sugar beet and fodder beet), pomes, drupes and soft fruit (apples, pears, plums, peaches, almonds, cherries, strawberries, raspberries and blackberries), leguminous plants (beans, lentils, peas, soybeans), oil plants (rape, mustard, poppy, olives, sunflowers, coconut, castor oil plants, cocoa beans, groundnuts), cucumber plants (cucumber, marrows, melons), fibre plants (cotton, flax, hemp, jute), citrus fruit (oranges, lemons, grapefruit, mandarins), vegetables (spinach, lettuce, asparagus, cabbages, carrots, onions, tomatoes, potatoes, paprika), lauraceae (avocados, cinnamon, camphor), or plants such as tobacco, nuts, coffee, pineapples, sugar cane, tea, pepper, vines, hops, bananas and natural rubber plants, as well as ornamentals. This recitation is exemplary and constitutes no limitation.

The compounds of formula I are normally applied in the form of compositions and can be applied to the crop area or plant to be treated, simultaneously or in succession, with further compounds. These further compounds may be both fertilisers or micronutrient donors or other substances that influence plant growth. They can also be selective herbicides, insecticides, fungicides, bactericides, nematicides, mollusicides or mixtures of several of these substances, optionally in conjunction with further carriers, surfactants or application promoting adjuvants customarily employed in the art of formulation.

Suitable carriers and adjuvants may be solid or liquid and correspond to the substances ordinarily employed in formulation technology, e.g. natural or regenerated mineral substances, solvents, disper :ants, wetting agents, tackifiers, thickeners, binders or fertilisers.

A preferred method of applying a compound of formula I or an agrochemical composition which contains at least one of said compounds is foliar application. The frequency of application and the rate of application will depend on the risk of infestation by the corresponding pathogen. The compounds of formula I may also be applied to seeds (coating) by impregnating the seeds either with a liquid formulation comprising a compound of formula I, or coating them with a solid formulation.

The compounds of formula I are used in unmodified form or, preferably, together with the adjuvants conventionally employed in the art of formulation, and are therefore formulated in known manner to emulsifiable concentrates, coatable pastes, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granulates, and also encapsulations in e.g. polymeric substances. Just as with the type of the compositions, the methods of application such as spraying, atomising, dusting, scattering, coating or pouring are chosen in accordance with the intended objectives and the prevailing circumstances.

Advantageous rates of application are normally from 5 g to 2 kg of active ingredient (a.i.) per hectare, preferably from 10 g to 1 kg a.i. ha, most preferably from 20 g to 600 g a.i./ha.

The formulations, i.e. the compositions comprising the compound (active ingredient) of formula I and, where appropriate, a solid or liquid adjuvant, are prepared in known manner, typically by intimately mixing or grinding the active ingredient with extenders such as solvents, solid carriers and, in some cases, surfactants.

Suitable solvents are: aromatic and aliphatic hydrocarbons, preferably the fractions contianing 8 to 12 carbon atoms, e.g. xylene mixtures or substituted naphthalenes, phthalates such as dibutyl or dioctyl phthalate; aliphatic hydrocarbons such as cyclohexane or paraffins; alcohols and glycols and their ethers and esters, including ethanol, ethylene glycol, ethylene glycol monomethyl or monoethyl ether; ketones such as cyclohexanone; strongly polar solvents such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethyl formamide; as well as vegetable oils or epoxidised vegetable oils such as epoxidised coconut oil or soybean oil; and water.

The solid carriers typically used for dusts and dispersible powders are usually natural mineral fillers such as calcite, talcum, kaolin, montmorillonite or attapulgite. To enhance the physical properties it is also possible to add highly dispersed silicic acid or highly dispersed absorbent polymers. Suitable granulated adsorptive carriers are porous types, for example pumice, broken brick, sepiolite or bentonite; and suitable nonsorbent carriers are materials such as calcite or sand. In addition, a great number of pregranulated materials of inorganic or organic nature can be used, typically dolomite or pulverised plant residues.

Depending on the type of the compound of formula I to be formulated, suitable surface-active compounds are non-ionic, cationic and/or anionic surfactants having good emulsifying, dispersing and wetting properties. The term surfactants will also be understood as embracing mixtures of surfactants.

Suitable anionic surfactants can be both water-soluble soaps and water-soluble synthetic surfactants. Illustrative examples of nonionic surfactants are nonylphenolpolyethoxyethanols, castor oil polyglycol ethers, polypropylene/polyethylene oxide adducts, tributylphenoxypoly- ethyleneethanol, polyethylene glycol and octylphenoxypolyethoxyethanol. Fatty acid esters of polyoxyethylene sorbitan, e.g. polyoxyethylene sorbitan trioleate, are also suitable nonionic surfactants.

Cationic surfactants are preferably quaternary ammonium salts which contain at least one alkyl radical of 8 to 22 carbon atoms as N-substituent and, as further substituents, unsubstituted or halogenated lower alkyl or benzyl radicals or lower hydroxyalkyl radicals.

Further surfactants customarily employed in formulation technology are known to those skilled in the art or may be found in the relevant literature.

The agrochemical formulations will usually comprise OJ to 99 % by weight, preferably 0.1 to 95 % by weight, of a compound of formula I, 99.9 to 1 % by weight, preferably 99.8 to 5 % by weight, of a solid or liquid adjuvant, and 0 to 25 % by weight, prefereably OJ to 25 % by weight, of a surfactant

Whereas commercial products will preferably be formulated as concentrates, the end user will normally employ dilute formulations.

The compositions may also contain further auxiliaries such as stabilisers, antifoams, viscosity regulators, binders, tackifiers as well as fertilisers or other chemical agents for obtaining special effects.

The invention is illustrated in more detail by the following non-limitative Examples. Preparative Examples

l(3)-(Dimethylaminosulfonyl)-2-thioamido-5-chloro-6-difluoromethoxybenzimidazole (compound 1.6)

[compound 1.6]

4.7 g of l(3)-(dimethylaminosulfonyl)-2-cyano-5-chloro-6-difluoromethoxybenzimidazole are dissolved in 60 ml of dioxane. To the solution is added 0.7 g of triethylamine and then hydrogen sulfide is introduced over 20 minutes. After stirring for 30 minutes, the reaction mixture is poured into 500 ml of ice- water and the product is extracted with ethyl acetate. The organic phase is washed with brine, dried over magnesium sulfate and concentrated. The red oil is stirred in ether and the crystallised product is isolated by filtration and dried. Yield: 4.0 g; m.p. 143- 145 °C. The --H-NMR spectrum shows that a c. 1:1 mixture (1,3) is obtained.

l(3)-(Dimethylaminosulfonyl)-2-cyano-5-chloro-6-difluoromethoxybenzimidazole (compound 1.5)

To 7.8 g of 2-cyano-5-chloro-6-difluoromethoxybenzimidazole in 100 ml of acetone are added 2.5 g of potassium hydroxide powder (85 %), followed by the slow dropwise addition of a solution of dimethyl sulfamoyl chloride (6.9 g) in 15 ml of acetone. The reaction mixture is stirred for 3 hours at room temperature, filtered over Hyflo, and the filtrate is concentrated under reduced pressure on a rotary evaporator. The residue is dissolved in methylene chloride. A minor amount of silica gel is added and the batch is stirred for 10 minutes and filtered. The filtrate is concentrated, the residue is stirred in ether and the product is finally isolated by filtration. Yield: 7.45 g. The -Η-NMR spectrum shows that a c. 1:1 mixture (1,3) is obtained.

2-Cyano-5-chloro-6-difluoromethoxybenzimidazole 20.3 g of methyl 2,2,2-trichloroacetimidate are added dropwise to l,2-diamino-4-chloro- 5-difluoromethoxybenzene (16.0 g) dissolved in 130 ml of acetic acid and the mixture is stirred for 1 hour at room temperature. The reaction mixture is poured into water, extracted with ethyl acetate, and the organic extract is concentrated on a rotary evaporator. The residue (2-trichloromethyl-5-chloro-6-difluoromethylbenzimidazole) is dissolved in 160 ml of tetrahydrofuran and the solution is slowly added dropwise to a 25 % ammonia solution (260 ml). The ensuing reaction is slightly exothermic. The reaction mixture is stirred for about 1 hour at room temperature and then filtered. The bright powder is dissolved in ethyl acetate, the solution is dried over magnesium sulfate, filtered and concentrated, giving 11.84 g of a pure product (analysis by TLC; methyl acetate:hexane 2:l.

l,2-Diamino-5-chloro-6-difluoromethoxybenzene

2-Nitro-4-difluoromethoxy-5-chloroaniline (35 g) are dissolved in 700 ml of tetrahydro¬ furan and Raney nickel is added as hydrogenation catalyst. Hydrogenation is carried out under normal pressure at room temperature until the uptake of hydrogen has ceased. After conventional working up, 30.3 g of the reduced compounds are obtained pure.

2-Nitro-4-difluoromethoxy-5-chloroaniline

A solution of 60 g of 2-nitro-4-hydroxy-5-chloroaniline in 450 ml of dioxane is added dropwise to a 15 % solution of sodium hydroxide (900 ml). The reaction mixture is heated to c. 75 °C and freon 22 is slowly passed in. During this addition a further 480 ml of 30 % sodium hydroxide solution are added at intervals. Freon 22 is passed in until almost complete reaction of the educt. After cooling, the reaction product is poured into water (3 1). The product precipitates as a crystalline solid while stirring uniformly. This product is isolated by filtration, washed with water, and dissolved in ethyl acetate. The solution is washed with brine, dried over magnesium sulfate and concentrated, giving 40.8 g of an orange powder.

The following products are prepared in analogous manner.

Cmpd. (Ri)a R R. phys. data

1.23 5-F CN CH₃ O 1.24 5-F CN N(CH₃)₂ O 1.25 5-F CSNH₂ N(CH₃)₂ O 1.26 4-Cl CN CH₃ O 1.27 4-Cl CN N(CH₃)₂ O 1.28 4-Cl CSNH₂ N(CH₃)₂ O 1.29 4-Br CSNH₂ N(CH₃)₂ O 1.30 4-Br CSNH₂ CH₃ O 1.31 4-Cl CN CH₃ S 1.32 4-Cl CN N(CH₃)₂ s 1.33 H CN N(CH₃)₂ s m.p. 102-106°C 1.34 H CSNH₂ N(CH₃)₂ s m.p. 186-187°C 1.35 H CN CH₃ s m.p. 119-122°C 1.36 H CSNH₂ CH₃ s 1.37 4-Br CSNH₂ CH₃ s 1.38 5-Cl CN CH₃ s m.p. 143-144°C 1.39 5-Cl CN N(CH₃)₂ s m.p. 119-120°C 1.40 5-Cl CSNH₂ N(CH₃)₂ s m.p. 178-180°C 1.41 5-Cl CSNH₂ CH₃ s 1.42 4-CF₃ CN N(CH₃)₂ O 1.43 4-CF₃ CSNH₂ N(CH₃)₂ O 1.44 4-CF₃ CN CH₃ O 1.45 H C(SCH₃)=NH N(CH₃)₂ s

Formulation Examples for compounds of formula I (throughout, percentages are by weight)

2J. Wettable powder a) b) c) compound of Table 1 25 % 50 % 75 %

Na ligninsulfonate 5 % 5 %

Na laurylsulfate 3 % _ 5 %

Na diisobutylnaphthalene- sulfonate 6 % 10 % octylphenol polyethylene gly col ether

(7-8 mol EO) - 2 % - highly dispersed silica 5 % 10 % 10 % kaolin 5 % 10 % 10 %

The active ingredient is thoroughly mixed with the adjuvants and the mixture is thoroughly ground in a suitable mill to give a wettable powders which can be diluted with water to give suspensions of any desired concentration.

2.2 Emulsifiable Concentrates compound of Table 1 10%

Ca dodecylbenzenesulfonate 3 % octylphenol polyethylene glycol ether (4-5 Mol EO) 3 % castor oil polyethylene glycol ether

(35 mol EO) 4 % cyclohexanone 30 % xylene mixture 50 %

Emulsions of any desired concentration can be prepared from such concentrates by dilution with water.

2.3 Dusts a) b) compound of Table 1 5 % 8 % talcum 95 % _ kaolin 92 %

Ready for use dusts are obtained by intimately mixing the carriers with the active ingredient.

2.4 Extruder granulate compound of Table 1 10 % Na ligninsulfonate 2 % carboxymethyl cellulose 1 % kaolin 87 % The active ingredient is mixed with the adjuvants, the mixture is ground and moistened with water. This mixture is extruded and subsequently dried in a stream of air.

5. Coated granulate compound of Table 1 3 % polyethylene glycol (MW 200) 3 % kaolin 94 %

(MW = molecular weight)

The finely ground active ingredient is uniformly applied to the kaolin moistened with polyethylene glycol in a mixer to give a non-dusting coated granulate.

6. Suspension concentrate compound of Table 1 40% ethylene glycol 10 % nonylphenol polyethylene glycol ether

(15 mol EO) 6 %

Na ligninsulfonate 10 % carboxymethyl cellulose 1 %

37 % aqueous solution of formaldehyde 0.2 % silicone oil in the form of a 75 % aqueous emulsion 0.8 % water 32 %

The finely ground active ingredient is intimately mixed with the adjuvants to give a suspension concentrate from which suspensions of any desired concentration can be prepared by dilution with water.

3. Biological Examples

Example 3.L: Action against Plasmopara viticola on vines a) Residual protective action

Vine seedlings in the 4-5 leaf stage are sprayed with a spray mixture (0.02 % a.i.) prepared from a wettable powder formulation of the test compound. After 24 hours the treated plants are infected with a sporangia suspension of the fungus. Fungal infestation is evaluated after incubation for 6 days at 95-100 % relative humidity and 20°C.

b) Residual curative action

Vine seedlings in the 4-5 leaf stage are infected with a sporangia suspension of the fungus. After incubation for 24 hours in a climatic chamber at 95-100 % relative humidity and 20°C, the infected plants are dried and sprayed with a spray mixture (0.02 % a.i.) prepared with a wettable powder formulation of the test compound. After the spray coating has dried, the treated plants are put once more into the conditioning room. Evaluation of fungal infestation is made 6 days after infection.

Compounds of formula I exhibit a very good fungicidal action against Plasmopara viticola on vines. In particualr, compounds 1J-1.7, 1J4, 1J5, 1.33, 1.35 and others inhibit infestation completely (residual infestation 0 to 5 %). In contradistinction thereto, infestation of untreated and infected control plants is 100 %.

Example 3.2: Action against Phytophthora on tomato plants

Residual protective action

After a cultivation period of 3 weeks, tomato plants are sprayed with a spray mixture

(0.02 % a.i.) prepared from a wettable powder formulation of the test compound. After

24 hours the treated plants are infected with a sporangia suspension of the fungus.

Evaluation of fungal infestation is made after incubation of the infected plants for 5 days at 90-100 % relative humidity and 20°C.

Compounds of Table 1 have a long-lasting action (less than 20 % infestation). Compounds 1J-1.7, 1J4, 1J5, 1.33, 1.35 and others inhibit infestation almost completely (0 to 5 % infestation). In contradistinction thereto, Phytophthora infestation of untreated and infected control plants is 100 %.

Example 3.3: Action against Phytophthora on potato plants

Residual protective action

After a cultivation period of 3 weeks, 2-to 3-week-old potato plants (Bintje variety) are sprayed with a spray mixture (0.02 % a.i.) prepared from a wettable powder formulation of the test compound. After 24 hours the treated plants are infected with a sporangia suspension of the fungus. Evaluation of fungal infestation is made after incubation of the infected plants for 5 days at 90-100 % relative humidity and 20°C. Compounds of Table 1 have a long-lasting action (less than 20 % infestation). Compounds 1J-1.7 and others inhibit infestation almost completely (0 to 5 % infestation). In contradistinction thereto, Phytophthora infestation of untreated and infected control plants is 100 %.

Example 3.4: Action against Pythium debaryanum on sugar beet (Beta vulgaris) The fungus is cultivated on sterile oat grains and blended with a mixture of earth and sand. Flower pots are filled with the infected soil and sown with sugar beet seeds. Immediately after sowing, aqueous suspensions of the test compounds formulated as wettable powders are poured over the soil (20 ppm a.i., based on the volume of the soil). The pots are then placed in a greenhouse for 2-3 weeks at 24-26°C. The soil is continually kept uniformly moist by lightly spraying it with water. The test is evaluated by determining the emergence of the sugar beet plants as well as the number of healthy and sick plants.

b) Action after seed dressing

The fungus is cultivated on sterile oat grains and blended with a mixture of earth and sand. Flower pots are filled with the infected soil and sown with sugar beet seeds dressed with test compounds formulated as seed dressing powders (1000 ppm a.i., based on the weight of the seeds). The pots in whuch the seeds have been sown are then placed in a greenhouse for 2-3 weeks at 20-24°C. The soil is continually kept uniformly moist by lightly spraying it with water. The test is evaluated by determining the emergence of the sugar beet plants as well as the number of healthy and sick plants.

After treatment with compounds of formula I according to Table 1 more than 80 % of the plants emerge and have a healthy appearance. Only isolated emergent plants of sickly appearance are observed in the control pots.

Example 3.5: Direct action against Peronospora tabacina

A formulation of the test compound is mixed in different concentrations (10, 1, 0J ppm) with water-agar and the mixture is poured into petri dishes. After cooling, 100 μl of a sporangia suspension (10⁶ spores/ml) are streaked on to the plate. The plates are incubated for 16 hours at 18 °C.

The compounds of Table 1 inhibit the germination of Peronospora tabacina.

Claims

What is claimed is:

1. A benzimidazolesulfonic acid derivative of formula I

wherein the R₃SO₂ group is in 1- or 3-position and, in relation to the two substituents F₂HC-X- and R_j, forms pure or mixed position isomers, and wherein the substituents have the following meanings:

Rj is halogen which may be identical or different, C_rC₃alkyl, C_rC₃alkoxy and

C_rC₃haloalkyl;

R₂ is cyano, CSNH₂ or -C(SR')=NH, where R' is C_rC₄alkyl;

R₃ is C_rC₄alkyl or N(R")(R"'), where R" and R"' are identical or different C_rC₃alkyl;

X is oxygen or sulfur, and n is 0, 1 or 2.

2. A benzimidazolesulfonic acid derivative of formula I according to claim 1, wherein R_j is halogen, C_rC₃alkyl, C_rC₃alkoxy or CF₃, R₂ is cyano, CSNH₂ or -C(SR')=NH, where R' is C_rC₄alkyl, R₃ is C_rC₄alkyl or N(CH₃)₂, and X is sulfur.

3. A benzimidazolesulfonic acid derivative of formula I according to claim 1, wherein R₁ is halogen, C_rC₃alkyl, C_rC₃alkoxy or CF₃, R₂ is cyano, CSNH₂ or -C(SR')=NH, where R" is C_rC₄alkyl, R₃ is C_rC₄alkyl or N(CH₃)₂, and X is oxygen.

4. A compound according to claim 1, wherein R₂ is -CSNH₂.

5. A compound according to claim 1, wherein R₂ is cyano.

6. A compound of formula I according to claim 1„ selected from the group consisting of: l(3)-(dimethyla^'minosulfonyl)-2-cyano-5-chloro-6-difluoromethoxybenzimidazole, l(3)-(dimethylaminosulfonyl)-2-thioamido-5-chloro-6-difluoromethoxybenzimidazole, l(3)-(dimethylaminosulfonyl)-2-cyano-6-difluoromethoxybenzimidazole, l(3)-(dimethylaminosulfonyl)-2-cyano-4-bromo-6-difluoromethoxybenzimidazole, l(3)-(methylsulfonyl)-2-cyano-4-bromo-6-difluoromethoxybenzimidazole, l(3)-(dimethylaminosulfonyl)-2-cyano-4-bromo-6-difluoromethylthiobenzimidazole, l(3)-(dimethylaminosulfonyl)-2-cyano-5-trifluoromethyl-6-difluoromethoxybenzimida- zole, l(3)-(dimethylaminosulfonyl)-2-thioamido-5-trifluoromethyl-6-difluoromethoxybenz- imidazole, l(3)-(dimethylaminosulfonyl)-2-cyano-6-difluoromethylthiobenzimidazole, l(3)-(dimethylaminosulfonyl)-2-thioamido-5-chloro-6-difiuoromethylthiobenzimidazole.

7. A compound of formula II'

wherein R_lt X and n are as defined in claim 1.

8. A process for the preparation of a compound of formula I according to claim 1, which comprises reacting a compound of formula II

with a compound of formula in

Q-SO₂-R₃ (HI)

wherein R_j, R₂, R₃, X and n are as defined for formula I, and M is hydrogen or an alkali metal, and Q is a halogen atom or the radical O-SO₂-R₃, in an inert solvent and in the absence or presence of a base, in the temperature range from -30° to +180°C.

9. A composition for controlling and preventing infestation of plants by microorganisms, which composition comprises aas active ingredient a compound of formula I as claimed in claim 1, together with a suitable carrier material.

10. A composition according to claim 9, which comprises as active ingredient a compound as claimed in any one of claims 2 to 5.

11. A composition according to claim 9, which comprises as active ingredient a compound as claimed in claim 6.

12. A method of controlling or preventing the infestation of plants by microoganisms, which comprises applying a microbicidally effective amount of a compound of formula I as claimed in claim 1 to said plants, to parts of plants or to the locus thereof.

13. Use of a compound as claimed in claim 1 as microbicide.