IL46607A - Fungicidal compositions containing diesters of phosphorous acid - Google Patents

Abstract

1449443 Disubstituted phosphonates PHILAGRO 7 March 1975 [8 March 1974] 9541/75 Heading C2P [Also in Division A5] Phosphonates of the general formula in which R and R<SP>1</SP>, which may be the same or different, represent a linear or branched chain alkyl radical, which may optionally be substituted, e.g. by halogen or -OH groups, and which contains 1-18 C atoms, an optionally substituted cyclohexyl or phenyl radical or a heterocyclic radical connected to an oxygen atom adjacent the phosphorus by an aliphatic chain of 1 or 2 carbon atoms are prepared by reacting the appropriate alcohol with PCl 3 or H 3 PO 4 or by reacting a salt of a monoester of phosphonic acid with a haloformate. Exemplified are the preparation of O,O-diethyl phosphonate, O,O-di-n-propyl phosphonate, O,O-diisopropyl phosphonate, O,O-di-2-chloroethyl phosphonate, O,O-di-methoxy ethyl phosphonate, O,O-di-cyclohexylphosphonate, O,O-ditetra hydrofurfuryl phosphonate and O-methyl, O-ethyl phosphonate. [GB1449443A]

Description

46607/2 ft'nmrn nsoinn Fungicidal compositions containing dieaters of phosphorous acid PHI GRO C. 44575 This invention relates to fungicidal compositions based on diesters of phosphorous acid (or phosphonates and their salts.

These compounds are sometimes also referred to as dialkyl (or aryl ....) phosphites.

More particularly, the invention relates to compositions which are suitable for use in controlling parasitic fungi, especially mildews, in plants and whi^ch contain as active ingredient at least one compound corresponding to the general formula: in which R and R', which may be the same or different, represent a linear or branched alkyl radical, which may optionally be substituted, by halogens or alkoxy groups, and which contains from 1 to 18 carbon atoms, a cyclohexyl or phenyl radical or a saturated 5 or 6 -membered heterocyclic radical connected to an oxygen atom adjacent the phosphorus by an aliphatic chain of 1 or 2 carbon atoms.

One preferred sub-group comprises compounds of the followki formula: iti which R and R' , whih may be the same or, preferably, different, represent a linear or branched, optionally halogen- or alkoxy-substituted alkyl radical containing 1 to 4 carbon atoms.

Most of these compounds are known per se. In particular, GB-PS 1,051,965 describes a process for the preparation of phosphonic acid esters in which one of the substituents is a lower alkyl radical and the other an optionally substituted alkyl, aralkyl or aryl radical. These compounds, like the corresponding phosphates, have pesticidal properties, but none of them is illustrated in the above-mentioned GB-PS.

It has now been found that the compounds according to the invention show excellent fungicidal properties and, in particular, are remarkably active against mildews, such as mildew of the vine, tobacco mildew and hop mildew.

These compounds may be obtained by the methods described in Houben-Weyl XII/2, pp. 20 - 37, which differ according to whether it is desired to obtain symmetrical or asymmetrical phosphonic esters.

Some symmetrical compounds are produced on an industrial scale and are commercially available. These compounds are in particular 0,0-dimethyl phosphonate, 0,0-diethyl phosphonate, 0,0-di-n-butyl phosphonate, 0,0-di-n-hexyl phosphonate, 0,0-di-2-ethyl-n-hexyl phosphonate, 0,0-di-n-octyl phosphonate, 0,0-di-n-dodccyl phosphonate, .0,0-n-he::adecyl phosphonate, 0,0-diphenyl phosphonate.

The other compounds may be prepared by the method described by Mc COMBIE in Journal of the Chemical Society, LONDON (1945), page 380, in accordance with the following scheme: 3 ROH + PCI- (R0) POH + 2 HC1 + RCl 0,0-Diethyl phosphortate is prepared in this way: r- 1 mol of phosphorus trichloride in solution in 150 ml of {I carbon tetrachloride is added with stirring to a solution of 3 mols of ethanol in 225 ml of carbon tetrachloride. The mixture is heated for 30 minutes to 90°C. Dry nitrogen is then bubbled through the reaction mixture in order to remove the volatile compounds. Following removal of the solvent, the product is distilled in vacuo.

Yield: 93 % b.p.„14, mm H„g : 73 - 74°C n^ : 1.4080 It was possible by this method to synthesise the compounds identified along with their characteristics in the following Table: In cases where R and R' are long-chain substituents , it is preferred to react phosphorous acid with an alcohol under reflux in toluene, cf. GB-PS 699,154: 2 ROH + H3 P03 =s»(R0)2 POH + 2H20 The asymmetrical compounds may be prepared by the method described in GB-PS 1,051,965 referred to above, or by the method described in DT-PS 1 ,216,278 v/hich comprise reacting a salt of a monoester of phosphonic acid with a haloformate in accordance with the following scheme: 0-Methyl and 0-ethyl phosphonate were prepared by this method: Methyl chloroformate is reacted with sodium ethyl phosphite in methylene chloride at ambient temperature.

After filtration and evaporation of the solvent, the product is distilled in vacuo. b.p.._ ,.·: 63 - 64°C 9 2 mm Hg n : 1.4050 yield: 72 % The following Examples illustrate the fungicidal properties of the following compounds: (1) 0,0-dirnethy1 phosphonate - (2) 0,0-diethyl phosphonate (3) 0,0-di-n-propyl phosphonate - (4) 0,0-diisopropyl phosphonate (5) 0,0-di-n-butyl phosphonate (6) Ο,Ο-dimGthoxy ethyl phosphonate (7) 0,0-diphenyl phosphonate ^ (8) 0,0-dicyclohexyl phosphonate (9) O-methyl, O-ethyl phosphonate.

EXAMPLE 1 : In vivo test on Plasmopara viticola in vine plants a) Preventive treatment The leaves of pot-grown vine plants (Gamay variety) are sprayed underneath using a spray gun with an aqueous suspension of a wettable powder having the following composition (by weight): active material to be tested 20 % deflocculant (calcium lignosulphate) 5 % wetting agent (sodium alkyl aryl sulphonate) .... 1 % filler (aluminium silicate) 74 % in the required dilution containing the active material to be tested in the required dose. Each test was repeated three times .

After 48 hours, the plants are contaminated by spraying the leaves underneath with an aqueous suspension of approximately 80,000 units/cc of spores of the fungus.

The pots are then placed in an incubation cell at 20°C/100 % relative humidity for a period of 48 hours.

The plants are inspected 9 days after infestation.

Under these conditions, it was found that, in a dose of 0.5 g/1, compounds 1, 2, 6, 8 and 9 afford total protection, whilst compounds 3 and 5 afford good protection.

In addition, it was found that none of the compounds tested showed the least phytotoxicity . b) Treatment after contamination The proecedure is as described in a) above, except that the plants are first of all contaminated and then treated with the active material to be tested, the plants being inspected^ 9 days after contamination.

Under these conditions, it was found that, in a dose of 1 g/1, compounds 1,2,3,6 and 8 complete^ stop growth of the mildew on the vine plants.

EXAMPLE 2 : Systemic test by root absorption on vine mildew Several vine stocks (Gamay variety) each accommodated in a pot containing vermiculite and a nutritive solution are sprinkled with 40 cc of a solution containing 0.5 g/1 of the material to be tested. After 2 days, the vine is contaminated with an aqueous suspension containing 100,000 spores/cc of Plasmopara viticola. The spores are then left to incubate for 48 hours in a room at 20°C/100 % relative humidity. The degree of infestation is assessed after about 9 days in relation to an infested control which has been sprinkled with 40 cc of distilled water.

Under these conditions, it was found that compounds 1, 2, 3, 4, 5 and 9 absorbed by the roots afford total protection to the vine leaves . against mildew, which demonstrates clearly the systemic nature of these compounds.

EXAMPLE 3: Systemic test by leaf absorption on mildew of the vin Vine stocks (Gamay variety) each accommodated in a pot containing a mixture of clean soil and sand, are treated at the 7- leaf stage.

The treatment is carried out by spraying the lowest 4 leaves underneath with a wettable powder containing 2.5 g/1 of the active material to be tested.

After 2 days, the vine is contaminated with an aqueous suspension containing approximately 100,000 spores/cc of asmopara viticola. The spores are then left to incubate for 48 hours in a room at 20°C/100 % relative humidity.

The degree of infestation is assessed after about 9 days from the 5th to 7th leaves from the bottom in relation to a control which has been treated with distilled water. Under these conditions, it was found that compounds 1, 6, 7, 8 and 9 afford total protection to the upper leaves of the vine against mildew.

All these Examples clearly demonstrate the remarkable anti-mildew activity of the compounds according to the invention, being a systemic activity which both prevents and stops growth of the fungus. Accordingly, these compounds may be used both for the preventive treatment and for the curative treatment of plants susceptible to fungus disease caused, for example, by phycomycetes and ascomycetes, and in particular for the protection of vegetables such as, in particular, vines, hops or tobacco against mildews of the Plasmopara viticola, Peronospora tabacci or Pseudo peroponospora humili type.

In addition, these compounds may be used with advantage in admixture with one another or with other known fungicides, such as metal dithiocarbamates (manebe, zinebe, mancozebe), basic salts or hydroxides of copper (oxy chloride, oxy sulphate), (tetrahydro)phthalimides (captane, captafol, fol el), methyl -butyl ca bamoyl )-2-benz imidazole carbamate (benomyl), , 2-di- (3-methoxy or ethoxy)-2-carbonyl thioureidobenzenes (thiophanates) , methyl 2-benzimidazole carbamate, etc., either in order to complete the range of activity of the compounds according to the invention or to increase their persistence.

It has also been found that these compounds may be m e^ with other fungicidal phosphorus derivatives with anti-mildew activity, especially the optionally substituted 2-hydroxy- , 3 , dioxaphospholanes described in French Patent Application 73-01.803 and its Addition 73.37994, and with phosphorous acid and its salts, as described in French Patent Application 73-43.081, and with phosphonic monoesters and their salts, as described in French Patent Application 73-45.627.

The doses in which the compounds according to the invention are used may vary within wide limits, depending both upon the virulence of the fungus and upon the climatic conditions .

Doses of from 0.01 to 5 g/1 of active material are generally suitable.

For their practical application, the compounds according to the invention are rarely used on their own. Instead, they generally form part of formulations which, as a rule, contain a support and/or a surfactant in addition to the active material according to the invention.

• In the context of the invention, a support is an organic or mineral, natural or synthetic material with which the active material is associated to facilitate its application to the plant, to seeds or to soil, or its transportation or handling. The support can be solid (clays, natural or synthetic silicates, resins, waxes, solid fertilisers) or fluid (water, alcohols, ketones, petroleum fractions, chlorinated hydrocarbons, liquefied gases).

The surfactant can be an ionic or non- ionic emulsifier, dispersant or wetting agent such as, for example, salts of polyacrylic acids and lignin sulphonic acids, condensates of ethylene oxide with fatty alcohols, fatty acids or fatty amines .

The compositions according to the invention may be ^ prepared in the form of wettable powders, soluble powders, dusting powders, granulates, solutions, emulsifiable concentrates, emulsions, suspended concentrates and aerosols .

The wettable powders according to the invention can be prepared in such a way that they contain from 20 to 95 % by weight of the active material, and they normally contain, in addition to a solid support, from 0 to 5 % by weight of a wetting agent, from 3 to 10 % by weight of a dispersant and, when necessary, from 0 to 10 % by weight of one or more stabilisers and/or other additives, such as penetration agents, adhesives or antilumping agents, colorants, etc.

One example of the composition of a wettable powder is given below: active material 50 % calcium lignosulphate (deflocculant) 5 % - anionic wetting agent (alkylaryl sulphonate) .... 1 % antilumping silica 5 % - .kaolin (filler) 39 % The water-soluble powders are obtained in the usual way by mixing from 20 to 95 % by weight of the active material with 0 to 10 % of an antilumping filler, the balance bang made up by a solid water-soluble support , especially a salt.

One example of the composition of a soluble powder is iven below: active material 70 % anionic wetting agent 0.5 antilumping silica 5 % sodium sulphate (soluble support) 24.5 Aqueous dispersions and emulsions, for example compositions obtained by diluting with water a wettable powder or an 4 emulsifiable concentrate according to the invention, are included within the general scope of the invention. These emulsions can be of the water-in-oil type or of the oil-in-water type, and can have a thick consistency resembling that of a "mayonnaise".

The compositions according to the invention may contain other ingredients, for example protective colloids, adhesives or thickeners, thixotropic agents, stabilisers or sequestrants, as well as other active materials known to have pesticidal properties, especially acaricides or insecticides. 46607/2

Claims (8)

1. A fungicidal composition for controlling fungus disease in plants, wherein it contains an effective quantity of at least one compound corresponding to the general formula: in which R and R1, which, may be the same or different, represent an optionally halo or alkoxy substituted, linear or branched alkyl radical with 1 to 18 carbon atoms, a cyclohexyl or phenyl radical or a saturated 5-or 6-membered heterocyclic radical connected to an oxygen atom adjacent the phosphorus by an aliphatic chain of 1 or 2 carbon atoms

2. A composition as claimed in Claim 1 in admixture with a support and additives harmless to the plants, containing as active ingredient at least one compound corresponding to the formula: in which ¾ and R^, which may be the same or different, represent an optionally halogen- or alkoxy-substituted linear or branched alkyl radical with 1 to 4 carbon atoms.

3. > A composition as claimed in Claim 1, wherein the radicals R and R' are the same.

4. A composition as claimed in Claim 2, wherein the active ingredient is 46607/2 0,O-dimethyl phosphonate.

5. A composition as claimed in Claim 2, wherein the active ingredient is 0,0-diethyl phosphonate.

6. A composition as claimed in Claim 2, wherein the active ingredient is 0,0-dimethoxy ethyl phosphonate.

7. A process for controlling fungus disease in plants, comprising applying a composition of the kind claimed in any of Claims 1 to 6 for preventive or curative treatment.

8. A process as claimed in Claim 7, wherein the fungus disease is a mildew. PC/mm