IL29351A - O-alkyl s-phenyl benzyl phosphonothiolates,their preparation and their use as fungicides - Google Patents

Description

29351/2 New O-alkyl S-phenyl benzyl phoaphono tliiola es , their preparation and tJieir use as fungicidea HIH03J TOKUS J ΝΟΥΑΚΪ SEIZO KABU3HIKI KAISHA FARBBMPAEHIKi BAYER A.G.

C.27771 The present invention relates to organic phospho-thiolates vjhich are useful as agricultural and horticultural fungicides, their production, compositions comprising them and their use.

The fungicidally active compounds of the invention are O-alkyl S- henyl benzyl phosphonothiolates of the general formula wherein R is an alkyl group of 1 - 4 carbon atoms, X is a hydrogen atom, a chlorine atom or a methyl group, Y is a hydrogen atom, a chlorine atom, an alkyl group of 1 to 4 carbon atoms or an alkoxy group, and n is zero, 1 or 2.

Such compounds as phenyl mercuric acetate and methyl arsonic acid metal salts have been used extensively in the control of the rice diseases blast (Piricuralia oryzae) and sheath blight (Hypochnus sasakii)* They are effective and cheap but suffer the disadvantage that they are toxic to humans.

The O-alkyl S-phenyl benzy¾?hosphonothiolates of general formula (I) are useful as agricultural and horticultural fungicides and in particular they are effective against such rice diseases as blast, brown spot ( Cochliobolus miyabeanus) and sheath b g t* They do not contain heavy metals such as mercury and are non-toxic to man and cattle.

Table 1 illustrates compounds within the scope of the invention. 29351/2 Chemical name O-methyl S-phenyl beneylphoephonothio t* O-methyl S-(4-methyl« phenyl) benzylphoe- '·. phonothiolate ■.t Compound Structural formula Chemical name O-ethyl S-phenyl benzyl phosphonothiolate No. -CH2 O-ethyl S-(4-methyl- phenyl) benzylphos- 2H5O phono.thiolate O-iso-propyl S-phenyl benzylphosphonothiolate No. 6 O-methyl S-phenyl 4'· chlorobenzylpho s- phonothiolate No. 7 O-methyl S-(4-methyl- phenyl) 4' -chlorobenzyl- phosphonothiolate No. 8 O υ--eetxhnyylj. S o--pphneennyylj.4.'. chlorobenzylpho s- phonothiolate O-methyl S-( methyl - phenyl) 2Λ ,4' -dichloro- CH3 benzylphosphonothiolate » m O-ethyl S-phenyl 2»,4'· No. 10 dichlorobenzylphoe- phonothiolate Compound Structural formula Chemical O-methyl S-(4-chloro phenyl) benzylphos- phonothiolate No. 12 0-eth l S-(4-chloro phenyl) benzylphos- phonothiolate No. 13 0-methyl S-(4-chloro- phenyl) 4' -chlorobenzyl- phosphonothiolate 0-ethyl S-(4-chloro- phenyl) ' -chlorobenzyl phosphonothiolate 0-methyl S-(4-chloro- Phenyl) 2' ,4» -dichloro- benzylphosphonothiolate CI „ ,/· S-(4-chloro- No. 16 , -dichloro- sphonothiolate No. 17 „ 0-methyl S-phenyl 4'- / P-S- v methylbenzylphosphono- CH3O thiolate No. 18 0-methyl S-(4-chloro- phenyl) 4'-methylbenzyl- phosphonothiolate Compound Structural formula Chemical No. „ O-methyl S-(4-methyl- phenyl ) 4 ' -methylbenzyl- phosphonothiolate No. 20 0-methyl S-phenyl 4' ethylbenzylphosphono thiolate O-methyl S-phenyl 4' - methoxybenzylpho sphono thiolate The aforementioned such compounds may be easily produced by reacting benzylphosphonic acid alkyl ester chloride represented by the following formula (il) (wherein R, Y and n stand for the same as defined the formula (l) with a compound represented by the following formula (ill) (III) 29351/2 Compound Structural formula Chemioal name No.19 O-methyl S-(4-methyl- phenyl) 4'-methylbenzyl* phoephonothiolate No. 20 O-ethyl S-phenyl 4'- metyloenssylphoephoioo* thiolate No. 21 O-methyl S-phenyl 4*·. ethylbensylphoephono* thiolate No.22. O-methyl S-phenyl 4*· methoxybenzylphoephono* thiolate1 .

The compounds of the invention may be easily produced by reacting a benzylphosphonic acid alkyl ester chloride of the general formula wherein R, Y and n are as defined for formula (I)with a compound of the general formula (III) wherein X is as defined for formula (I), and M is hydrogen or an alkali metal atom. This process may be pepresented by the following reaction scheme:— The reaction may be carried out in the presence of an organic solvent, preferably with heating. Suitable organic solvents include liquid hydrocarbons (benzene, xylene and hexane), liquid chlorinated hydrocarbons, ethers and ketones.

The reaction may, particularly when M is a hydrogen atom, employ an acid-binding agent such as an organic base, for example triethylamine, benzyldimethylamine, pyridine or 2-mothyl-5-ethyl pyridine, or an inorganic base, for example sodium carbonate, potassium carbonate, sodium bicarbonate or potassium bicarbonate.

Reaction temperatures may be from 0°C. to 80°C.

The reaction time is dependent upon the reaction temperature, reaction components and other reaction conditions, however, reaction times of from one hour to 10 hours are usual.

Further, as occasion demands it is possible to carry out the reaction in a nitrogen gas stream.

After completion of the reaction, the product may be obtained by filtering off the salts produced, washing the filtrate with water or an aqueous solution of a carbonate, drying with anhydrous sodium sulphate and then removing the solvent, thereafter purifying the product as occasion demands.

Host of the compounds of formula (I) are oily substances generally insoluble in water, but soluble in organic solvents, for example, alcohols, benzene, xylene, hexane, ethers, ketones, chlorinated hydrocarbons and hydrocarbons.

The compounds of Formula I may be applied using various methods known in the agricultural and horticultural fields. Thus they can be diluted with water or mixed with various carriers and formulated into fungicidal compositions in •r the form of we able powders, emulsifiable concentrates, dusts, granules or pastes by methods generally used in agricultural chemical industry* Solid carriers which may be used include such inactive materials as talc, clay, kaolin, montmorillonite, diatomaceous earth and calcium carbonate. Liquid carriers can be either solvents or non-solvents which provide compositions in the form of solutions or dispersions. Suitable liquid carriers include alcohol, benzene, xylene, dimethylnaphthalene, aromatic naphtha and dimethylforniaaide. Liquid carriers can be used in association with surface active agents.

The active ingredients of formula I can be applied when mixed with adjuvants commonly used in the agricultural chemical industry, such as spreaders, emulsifiers, wetting agents or adhesive agents. Further, they can be applied in mixtures with such Insecticides, acaricides and nematocides as organo-phosphorus compounds, carbamate compounds, chlorinated compounds and dLnitro-compounds, such fungicides as organo^ phosphorus compounds, organic sulphur, copper compounds, dithiocarbamate compounds and dinitro-compounds, antibiotics, such herbicides as substituted phenoxy compounds, carbamate compounds, urea compounds, triazine compounds, chlorophenols, substituted diphenyl ethers and anilide compounds and other agricultural chemicals and fertilizers.

When using the fungicides of the invention in powder form, they can be directly dusted on the leaves or stems of plants or on the seeds. When in the form of emulsifiable concentrates, they can be diluted with water to a desirable concentration and then sprayed on the leaves and stems of plants. When in the form of wettable powders they can be The fungicides of this invention are ordinarily used in amounts sufficient to provide 25 g - 100 g, preferably 40 g - 100 g, especially 60 g - 80 g of the active ingredient per 10 acres However, if desired, they may be used in smaller or larger amounts. The amounts used vary depending upon the particular active ingredient, the method and time of application, the object of application, and the formulation of the fungicides.

One of the characteristics of the 0-alkyl S-phenyl ben-zylphosphonothiolates of the invention is that they have excellent fungicidal activit against blast, Brown spot and sheath blight, when compared with compounds in which the sulphur atom interposed between the phosporus atom and the group, in formula( I) is replaced by an oxygen atom. This will be illustrated in more detail in the followin examples which also illustrate the preparation of representative compounds of formula (I).

EXAMPLE 1 Preparation of the compound: 14.6 g of benzylphosphonic acid ethyl chloride and 7.5 g of 4-methylthiophenol were dissolved in 150 ml of benzene, 6 g of triethylamine were added dropwise with cooling and then the mixture was stireed for three hours at 60°C. After cooling, the be zene solution was washed with cold water and dried over anhydrous sodium sulphate. The benzene was distilled off and 14.9 g of pale yellow, oily, Q-ethyl S~(4-methyiphenyl) benzylphosphonothiolate were obtained at 150°0./0.1 mm Hg.

The benzylphosphonic acid alkyl ester chlorides used as starting materials in the preparation of compounds of formula I were manufactured according to the reaction scheme sh wherein R, Y and n are as defined hereinbefore. The compound benzylphosphonic acid ethyl ester chloride of formula:- "T-Cl C2H5( used in Example 1 was prepared as follows :- (A) 133.5 g of aluminium trichloride were suspended in 303 g of phosphorus trichloride and 63.3 g of benayl chloride were added gradually while stirring to give a uniform reaction mixture. Surplus phosphorus trichloride was distilled off under reduced pressure and the mixture was dissolved in 4 - 6 times its weight of dichloromethane and water added gradually at - 20°C. to - 15°C. until crystals of aluminium chloride hydrate separated out. After aluminium trichloride hydrate had been removed by filtration and dichloromethane distilled off, 66 g. of benzylphosphonyl dichloride were obtained at 107° - 8°C./ (B) 26 g. of the benzylphosphonyl dichloride from (A) were dissolved in 100 ml. of ether and cooled to 0°C. 6 g. of ethanol and 13 g. of triethylamine were dissolved in 100 ml. of ether and the mixture was added dropwise to the cooled ether solution while stirring below 0°C. After the completion of the addition, stirring was continued at 0°C. for two hours and the precipitate which formed was removed by filtration. The filtrate fras concentrated by distillation and the residue was distilled. 17.6 g. of benzyl hos honic acid ethyl ester chloride were obtained at 98°G./0.1 mm. Hg.

SXAMPIiE 2 Preparation of the compound: 17.0 g. of 4-chlorobenayl phosphonic acid ethyl ester chloride and 6.6 g. of thiophenol were dissolved in 150 ml. of benzene. 6 g. of triethylamine were added dropwise with cooling and the mixture was stirred for 10 hours at room temperature. The benzene solution was washed with cold water and dried over anhydrous sodium sulphate. The benzene ivas distilled off and 15.1 fg. of pale yellow, cily, 0-ethyl S--phenyl 4 ' -chlorobenzyl-phosphonothiolate were obtained at 140°0./0.1 mm. Hg.

EXAMPLE 3 Preparation of the compound; chloride and 8.7 g* of 4-ehlorothiophenol were dissolved in 150 ml. of benzene. 6 g. of triethylamine were added dropwise with cooling and the mixture was stirred for 2 hours at 70°C. After cooling, the benzene solution was washed with cold water and dried over anhydrous sodium sulphate. The benzene was distilled off and 14.4 g. of pale yellow, oily, 0-iaethyl S-(4-chlorophenyl) benzylphosphonothiolate were obtained at 140°C./0.1 ram. Hg.

EXAMPLE 4 Preparation of the compound: · g. of 4-methylbenzylphosphonic acid ethyl ester chloride and 6.6 g. of thiophenol were dissolved in 160 ml. of benzene. 6.0 g. of triethylamine were added dropwise with cooling and the mixture was stirred for 10 hours at room temperature. The benzene solution was washed with cold water and dried over anhydrous sodium sulphate. The benzene was distilled off and 14.0 g. of pale yellow, oily, 0-ethyl S-phenyl 4 '-methyl-benzylphosphonothiolate were obtained at 150°C./Q.l mm. Hg.

The following Examples 5 to 12 illustrate the preparation of fungicidal compositions.

EXAMPLE 5 40 Parts of 0-methyl S-(4-methylphenyl) benzylphosphonothiolate, 58 parts of clay and 2 parts of the emulsifier Sorpol ¥ - 150 (trade name of the product of Toho EXAMPLE 6 50 Parts of 0-ethyl S-phenyl benzylphosphonothiolate, 30 parts of xylene and 20 parts of the emulsifier Sorpol 2020 (trade name of the product of Toho Kagaku Kogyo , Japan) were formulated into an emulsifiable concentrate by mixing and stirring. The concentrate was suitable for application when diluted with water.

EXAMPLE 7 2 Parts of 0-methyl S-phenyl benzylphosphonothiolate and 98 parts of a mixture of talc and clay were formulated into a powder by crushing and mixing. The composition was suitable for application in that form.

EXAMPLE 8 Parts of 0-ethyl S-phenyl 4 '-chlorobenzylphos-phonothiolate dissolved in a solvent were sprayed onto 95 parts ''! of mulmerised clay granules of 0.2 - 2 mm. in diameter in a rotating mixer (V-shaped). Granules were obtained after drying which were suitable for application in that form.

EXAMPLE 9 Parts of 0-methyl S-(4-chlorophenyl) benzylphosphonothiolate, 68 parts of cla and 2 parts of the emulsifier Sorpol W - 150 were formulated into a **ettable powder by crushing and mixing. The composition was suitable for application t-jhen diluted with water.

EXAMPLE 10 50 Parts of 0-methyl S-phenyl 4'-methylbenzyl-phosphonothiolate, 0 parts of xylene and 20 parts of the emulsifier Sorpol 2020 were formulated into an emulsifiable concentrate by mixing and stirring. The composition could be ' BXiUCPLE 11 # 2 Parts of O-methyl S-(4-fihlorophenyl) 4'-chloro-benzylphosphonothiolate and 98 parts of a mixture of talc and clay were formulated into a powder by crushing and mixing. The powder could be applied as it was.

EXAMPLE 12 Parts of O-toethyl S-( -chlorophenyl) benzylphos-phonothiolate dissolved in solvent were sprayed onto 95 parts of mulmerised clay granules of about 0.2 - 2 mm. in diameter in a rotating mixer (V-shaped) and granules were obtained after drying. The granules were suitable for application to the soil.

The following Example 13 illustrates the fungicidal activity of compounds of the present invention.

EXAMPLE 13 (i) Tests against blast (Pot test) Paddy rice (Jukkoku variety) was cultivated in pots 12 cm. in diameter and suspensions of the test compounds were sprayed on the rice plants at their young ear-forming period. From the next day the treated rice plants were kept in a greenhouse under conditions of high humidity at 25°0. for 48 hours* During that time a suspension of the spores of rice blast pathogen was twice sprayed on the plants to inoculate them.

The inoculated rice plants were kept in the greenhouse for a further 7 days and the attack rate of each was assessed on a scale from 0 (no attack) to 5 (heavy attack).

Comparison experiments were carried out using closely related pho3phonates and phenyl mercuric acetate and also using no fungicide. The results are summarised in Table II. (ii) Test against plant pathogen (agar dilution method) The test compounds were mixed In the agar culture medium of potato in the concentrations set out in Table III. After the medium had been poured into scales 9 cm., in diameter and coagulated, various plant pathogens were inoculated. After culturing at 27°G<. for 4 days, the growth of the plant pathogens was investigated and the minimuia concentration of active ingredient required to inhibit growth was determined. The results are summarised in Table III.

Table II The : experimental results of fungicidal effect against blast ( Pot test) The numbers of compound in the table are the same as those of the aforementioned table ( i) Table III Concentration of plant pathogen growth inhibition (agar dilution method) ppm shows minimum growth inhibition concentration.

Compounds Nos are the same with those shown in the aforementioned table (i) .

Zinc ethylene-his-(dithiocarb;amate) 29551/2

Claims (1)

1. CLAIMS of the general formula is an alkyl group of 1 to 4 carbon X is a hydrogen a chlorine atom or a methyl Y is a hydrogen a chlorine an alkyl group of 1 to 4 carbon atoms or an and n is 1 or benzylphosphonothiolates according to claim 1 wherein is an alkyl group of 1 to carbon X is a hydrogen atom or a methyl Y is a chlorine atom and n is 1 or phonothiola hyl 2 l hen phosphonothiolate 4 phosphonothiolate phosphonothiolate benzylphosphonothiolates according to claim 1 substantially as hereinbefore A process for the production of an benzylphosphonothiolate of the general formula in claim which comprises reacting a benzylphosphonic acid alkyl ester chloride of the general formula wherein and n are as defined in claim 1 with a compound of general formula wherein X is as defined in claim 1 and M is a hydrogen or an alkali metal A process according to claim wherein R is an group of 1 to 3 carbon atoms Y is a chlorine n is 1 or 2 and is a hydrogen atom or A process according to claim 26 or 27 wherein the reaction is carried ou in the presence of organic A process according to any of claims 26 to 28 wherein the reaction is carried out in the presence of an A process according to 26 substantially as hereinbefore A fungicidal composition as active an benzylphosphonothiolate as claimed in any of claims 1 to in association with a A fungicidal composition according to claim 31 stantially as hereinbefore A process for eradicating or preventing brown spot or sheath blight on rice plants which comprise applying a composition as claimed in claim o 32 to rice rice seeds or to the soil in which rice plants are growing or are to be A process according to claim 33 wherein the tions are applied in amounts providin from 25 to 100 of active ingredient per 10 A process according to claim substantially as hereinbefore insufficientOCRQuality