GB2177394A - Nematocidal benzamide derivatives - Google Patents

Abstract

Compounds of formula (I> <IMAGE> wherein X represents from 1 to 4 substituents selected from halo, C1-4 alkyl, C1-4 alkoxy, C1-4 alkylthio, nitro, trihalomethyl, amino, carboxamido, or aryl of up to 12 carbon atoms; Y represents hydrogen or halo; and R represents hydrogen or C1-4 alkyl, have use in combating nematode pests in plants.

Description

SPECIFICATION Benzamide derivatives This invention relates to novel benzamide derivatives, to compositions thereof useful for combating and controlling nematode pests of plants, and to processes for preparing the said benzamide derivatives.

In a first aspect the invention provides benzamide derivatives of the general formula:

wherein X represents from 1 to 4 substituents selected from halo, especially fluoro or chloro, C14 alkyl, C14 alkoxy, C14 alkylthio, nitro, trihalomethyl, amino, carboxamido, or aryl of up to 12 carbon atoms; Y represents hydrogen or halo, and R represents hydrogen or C, 4 alkyl.

In a preferred aspect the invention provides compounds of formula (I) wherein X represents one or two substituents selected from fluoro, chloro, C1-4 alkyl, trifluoromethyl, C1-4 alkoxy or phenyl. It is especially preferred that X (or at least one X if more than one) is present in the 3position with respect to the carboxamide group.

Specific examples of compounds according to formula (I) are those set forth in Table I in which the meanings of X, Y and R are given for each compound, together with the melting point. Each compound is in the form of the racemic (RS) pair of isomers with respect to the chiral carbon atom bearing the cyano group.

TABLE I

COMPOUND X Y R Melting Point NO. ( C) 1 3-Cl-5-Cl H H 215-216 2 4-CH3O 3-Cl H 133-134 3 H H H 159-160 4 2-Cl H H 130-131 5 3-Cl H H 139-140 6 2-Cl 4-Cl H 140-141 7 4-CH3O 4-Cl H 165-166 8 3-Cl 4-Cl H 170-171 9 4-Cl 4-Cl H 190-191 10 H 4-Cl H 156-157 11 3-NO2 4-Cl H 130-131 12 4-Cl H H 164-166 13 3-NO2 H H 182-183 14 4-CH3O H H 150-152 15 H H CH3 196-197 16 3-Cl-5-Cl H CH3 232-233 17 3-Cl-5-Cl 4-Cl CH3 208-209 18 H 4-Cl CH3 245-246 19 3-CH3 H H 163-164 20 3-CH3-5-CH3 H H 187-189 TABLE I (CONT'D)

COMPOUND X Y R Melting Point NO. ( C) 21 2-F-6-F H H 127-128 22 2-Cl-5-Cl H H 176-178 23 3-C2H5 H H 129-130 24 2-Cl-6-Cl H H 181-183 25 3-CH3O H H 126-127 26 3-CF3 H H 176-177 27 3-CH3S H H 122-123 28 3-C6H5 H H 145-146 29 3-NH2 H H 184-186 30 3-NHCOCH3 H H 208-209 The compounds of formula (I) may most conveniently be prepared by reacting a compound of formula II with a compound of formula III, preferably in the presence of a base such as anhydrous potassium carbonate, according to the following scheme.

wherein Z represents halo, especially chloro, X' is X as defined above except that it is not amino or carboxamido; and Y and R are as defined above in relation to formula (I). To obtain compound of formula (I) where X is amino or amido, a compound of formula (I) where X is nitro is reduced, for example with acid iron filings, to the corresponding amino compound which may be acylated with an carboxylic acid halide or anhydride.

The compounds of formula (I) are active against nematocide pests of plants. Suitably they are employed in the form of a composition.

In a further aspect the invention provides a nematocidal composition comprising a compound of formula (I) as hereinbefore defined in combination with a carrier or diluent.

In a further aspect the invention also provides a method of combatting nematode pests of plants by applying to the locus of the plants a compound of formula (I) or a composition comprising a compound of formula (I), hereinafter referred to as the active ingredient.

The method of the invention is most conveniently practised by applying a composition comprising a nematocidally effective concentration of the active ingredient to the soil in which the plants to be protected from nematode damage are growing or to be grown, for example by drenching the soil with the composition or by applying the composition in the form of granules or dusting powders. Alternatively, the roots of the young plants can be treated with the composition by dipping them prior to planting out. This method is particularly useful with plants which are transplanted at a particular time in their growth. Sometimes the seeds themselves can be treated with a preparation of the active ingredient before planting.

The method of the invention may also be practised by applying to the foliage of the plant a sprayable liquid composition either using a conventional spray system or an electrodynamic spray system, the compositions comprising from 0.00001% to 1% by weight of the active ingredients in volumes of between 10 and 1000 1/ha. The method may be widely practised on crops having aerial foliage and liable to infestation by soil dwelling nematodes, such as for example, vegetable crops such as potatos and tomatoes, citrus crops, tobacco, bananas, and root crops such as sugar beet.

Species of nematodes which may be controlled by the invention method include the following: Globodera rostochiensis (potato cyst nematode) Heterodera schachtii (beet cyst nematode) Meloidogyne incognita (root knot nematode) Meloidogyne javanica (tobacco root knot nematode) Pratylenchus penetrans (lesion nematode) Radophilus similis (burrowing nematode) Tylenchulus semipenetrans (citrus nematode) Compositions for use in the invention include sprayable liquid compositions or soil drenches obtained by water dilution of emulsifiable concentrates, suspension concentrates, soluble liquid compositions and the like. Such compositions may contain from 0.00001 to 1.0% by weight of the active ingredient.The concentrated compositions, in the form in which they are prepared, transported and stored, may contain from 0.5 to 50% by weight of the active ingredient, depending upon the type of composition. Generally soluble liquid compositions have lower concentrations of active ingredient than emulsifiable concentrates or suspension concentrates.

The compositions also contain surface active agent (emulsifying agents) in an amount from 1 to 20% by weight. These surface agents are usually selected from anionic types such as alkali metal or alkaline earth metal salts of sulphosuccinate or lignosulphonic acids, eg. sodium dioctylsulphosuccinate, sodium and calcium lignosulphonates, and nonionic types such as ethoxylated alkyl phenols and alcohols, eg. ethoxylated and nonylphenol. Suspension concentrates may also contain antisettling agents such as bentonite to improve the shelf life of the compositions.

The compositions may also be in the form of dusting powders wherein the active ingredient is mixed with a solid diluent or carrier, for example kaolin, bentonite, kieselguhr, or talc, or they may be in the form of granules, wherein the active ingredient is absorbed in a porous granular material for example pumice, gypsum or corn cob granules. Preferably, the granules contain from 1 to 20% by weight of the active ingredient which is absorbed onto the granule by, for example, spraying the granules with a solution of the active ingredient in a volatile solvent which is subsequently evaporated from the surface of the granules. Such solutions may contain other ingredients, for example a resin to regulate the rate of release of the active ingredient from the granules, or to help prevent premature disintegration or the granules.Alternatively the active ingredient in the form of a powder may be applied to the surface of the porous granular material using a water-soluble binder such as gum acacia, polyvinylalcohol or hydroxyethylcellulose.

Granules may be applied to the soil either in a band between the furrows defining the crop rows, or broadcast, and may if desired be lightly incorporated in the soil, or they may be placed in the furrows themselves at the time of planting the crop. Application of granules at a rate such that the amount of active ingredient is approximately 2 to 20 kg/ha is usually sufficient to control the pests, and a preferred rate is within the range 4 to 10 kg/ha of active ingredient.

The method of the invention is illustrated by the following Examples.

EXAMPLE 1 This Example illustrates the preparation of 2-(3,5-dichlorobenzamido)-2-phenylacetonitrile (Compound No 1, Table I).

A solution of potassium carbonate (5.0g) in water (25ml) was added to a stirred solution of phenylglycinonitrile hydrochloride (3g) in ether (25ml) at the ambient temperature. The yellow two phase mixture that resulted was stirred for a further 10 minutes and then cooled with an ice/salt both to 5"C. At this temperature, 3,5-dichlorobenzoylchloride (3.719) was added dropwise keeping the internal temperature below 10 C. During the addition, a precipitate of the product amide was formed. After the addition, the mixture was allowed to warm to the ambient temperature and stirred for a further 1 hour. The suspension was then filtered and the filter cake was washed with 20ml of ether.The resulting pale yellow solid was recrystallised from hexane/diethyl ether (3: 1) to yield a white solid (39) melting point 215-216"C.

C15H10Cl2N2O requires C, 59.03; H, 3.30; N, 9.18% found C, 59.28; H, 3.24; N, 9.25% EXAMPLE 2 This Example illustrates the preparation of 2-(3-chlorobenzamido)-2-phenylacetonitrile (Compound No 5, Table I). 3-Chlorobenzoyl chloride (2.659) was added slowly to a well stirred solution of water (20ml), ethyl acetate (20ml), anhydrous potassium carbonate (3.59) and 2phenylglycinonitrile hydrochloride (2.19) at the ambient temperature. The reaction was mildly exothermic, and was stirred for 1 hour, returning to the ambient temperature.After this period the reaction mixture was poured into ethyl acetate, the organic layer was separated, washed with water, dilute hydrochloric acid, and more water, dried over anhydrous magnesium sulphate, filtered and the solvent was removed in vacuo to leave a pale yellow solid which was recrystallised from ethanol/water to yield white crystals (1.69) melting point 139.5-140"C.

CIsHllCIN20 requires C, 66.55; H, 4.10; N, 10.35 found C, 66.35; H, 4.35; N, 10.48 EXAMPLE 3 This Example illustrates the preparation of 4-chlorophenylglycinonitrile and its conversion to 2 (2-chlorobenzamido)-2-(4-chlorophenyl)acetonitrile (Compound No 6, Table I).

A solution of 4-chlorobenzaldehyde (109) in methanol (4.0ml) was added to a stirred mixture of sodium cyanide (3.09) in water (4.0ml) and ammonium chloride (3.359) at the ambient temperature. After stirring for 1 hour a solution of .880 ammonia (10ml) was added and the reaction mixture was warmed to 60"C for 3 hours. After this time the red solution that had resulted was allowed to cool, then poured into water (300ml) and extracted with ether (2X100ml). The aqueous layer was discarded and the ether extracts were combined and washed with 2NHCI (100ml). The acid aqueous layer was separated off and washed with a further 50cm3 of ether, before neutralising with anhydrous sodium carbonate.The neutral aqueous layer was-extracted with ether (2 > C 100ml) and the ether layer then dried over anhydrous magnesium sulphate and evaporated to yield a red oil that crystallised on standing 79 IR- bands at 3250 and 3510cm h This solid was used for the preparation of Compound No 6 in which the 4-chlorophenylglycinonitrile (1.04g) in 10ml of ether was reacted with 2-chlorobenzoylchloride by the method of Example 1, yielding 0.89 of a pale yellow solid, melting point 140-141"C.

EXAMPLE 4 The following compounds were prepared from phenylglycinonitrile hydrochloride and the appropriately substituted benzoyl chloride by the method of Example 1 or Example 2: 3, 4, 12, 13, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28.

EXAMPLE 5 The following compounds were prepared from 4-chlorophenylglycinonitrile (see Example 3) by treatment of this with the appropriately substituted benzoyl chloride by the method of Example 1: 7,8, 9, 10, 11.

EXAMPLE 6 Acetophenone was treated by the method of Example 3 to prepare alpha-methyl phenylglycinonitrile which was used with benzoyl chloride and 3,5-dichlorobenzoyl chloride in the method of Example 1 to prepare Compounds 15 and 16 respectively. Similarly, 4-chloroacetophenone gave Compounds 17 and 18.

EXAMPLE 17 This Example illustrates the preparation of 2-(3-aminobenzamido)-2-phenylacetonitril (Compound No 29, Table I).

Iron fillings (1.709) were added to a stirred solution of Compound 13 (2.819) in 50% aqueous ethanol (20ml), at the ambient temperature. The mixture was heated to reflux with stirring. A solution of concentrated hydrochloric acid (0.13ml) in aqueous ethanol (5ml) was added dropwise to the hot solution. The mixture was refluxed with stirring for 3 hours. After cooling, the mixture was poured into ethyl acetate and filtered free of inorganic material. The solvent was removed in vacuo to give a yellow solid which was recrystallised from ethanol to yield cream coloured product (1.829) mpt 184-185.5"C, Compound No 29.

C15H,3N30 requires C, 71.70; H, 5.21; N, 16.72 found C, 71.53; H, 5.33; N, 16.78 EXAMPLE 8 This Example illustrates the preparation of 2-(3-acetamidobenzamido)-2-phenylacetonitrile (Compound No 30, Table I).

Acetic anhydride (0.53ml) was added to a stirred solution of Compound No 29 (1.409) and acetic acid (5ml) at the ambient temperature. The mixture was then heated to reflux with stirring for 2 hours. After cooling, the mixture was poured into water and the resultant mixture extracted with ethyl acetate. The organic extracts were washed with water, potassium carbonate solution (10% by volume) and more water, and then dried over anhydrous magnesium sulphate, filtered and the solvent was removed in vacuo to give a brown glassy solid which was recrystallised from ethyl acetate/60-80 petroleum ether, to yield cream coloured product (0.289), Compound No 30 melting point 208-209"C.

Cl7HlsN3o2-H2O requires C, 65.58; H, 5.50; N, 13.50 found C, 65.32; H, 5.57; N, 13.24 EXAMPLE 9 This Example illustrates the nematocidal propeties of the compounds of Formula I.

Tomato plants are planted in sterile soil and at 6-8 weeks old are transferred into a pot containing soil infested with root-knot nematodes (Meloidogyne incognita) and the soil is drenched with a composition containing 10 or 25 ppm of the compound under test (obtained by diluting 1 part of a solution of the compound in a 1:1 mixture of a acetone and ethanol with 99 parts of water containing 1% of a wetting agent) at a rate of 200ml/kg of soil. The roots of the plants.are examined after 3 weeks to determine the reduction in the number of root knots as compared with a similar treatment omitting the compound. The results are given in Table II as a grading of 0 to 9 where 0 represents from 0-10% reduction, 1 represents from 11 to 20% reduction, and so, on up to 9 which represents 91 to 100% reduction in the number of root knots formed.

TABLE II

COMPOUND GRADING NO. at 10 ppm 25 ppm 1 7 9 4 4 5 5 6 3 17 2 19 2 20 4 21 4 23 3 25 | - | 5 26 5 28 2 A dash - in Table II indicates that the compound was not tested at that rate.

Claims (11)

1. A compound of the formula (I):

wherein X represents from 1 to 4 substituents selected from halo, C1-4 alkyl, C1-4 alkoxy, C1-4 alkylthio, nitro, trihalomethyl, amino, carboxamido, or aryl of up to 12 carbon atoms; Y represents hydrogen or halo; and R represents hydrogen or C14 alkyl.

2. A compound according to claim 1 wherein X represents one or two substituents selected from fluoro, chloro, C1-4 alkyl, trifluoromethyl, CI 4 alkoxy or phenyl.

3. A compound according to claim 1 or claim 2 wherein a substituent X is present in the 3position with respect to the carboxamide group.

4. A process for preparing a compound of formula (I) as defined in claim 1, which process comprises reacting a compound of formula (II)

wherein X' is X as defined in claim 1 except that it is not amino or carboxamido and Z is halo; with a compound of formula (III)

wherein Y and R are as defined in claim 1; and thereafter if desired where X is nitro, carrying out one or both of the following steps: i) reducing the nitro group to amino; and ii) acylating the amino group to amido.

5. A process according to claim 4 wherein the reaction between the compound of formula (II) and the compound of formula (III) is carried out in the presence of a base.

6. A nematocidal composition comprising a compound of formula (I) as defined in claim 1 in combination with a carrier of diluent.

7. A method of combating nematode pests of plants by applying to the locus of the plant a compound of formula (I) as defined in claim 1 or a composition as defined in claim 6.

8. A compound substantially as hereinbefore described with reference to the examples.

9. A process for preparing a compound of formula (I) as defined in claim 1 substantially as hereinbefore described with reference to the examples.

10. A nematicidal composition substantially as hereinbefore described.

11. A method of combating nematode pests of plants substantially as hereinbefore described.