GB2031880A - 1,3,4-Oxadiazolin-5-one derivatives - Google Patents

Abstract

1,3,4-Oxadiazolin-5-one derivatives of the general formula: <IMAGE> (wherein X represents a halogen atom, R1, R2 and R3 have the same or different significances and each represents a hydrogen atom or a C1 to 3 alkyl radical, R4 represents a halogen atom, a C1 to 3 alkyl radical or a C1 to 3 alkoxy radical, and n represents zero or an integer from 1 to 4 inclusive) are new compounds useful as insecticides.

Description

SPECIFICATION 1,3,4-Oxadiazolin-5-one derivatives This invention relates to new 1 ,3,4-oxadiazolin-5-one derivatives useful as insecticides, to processes for their preparation and compositions containing them.

The 1,3,4-oxadiazolin-5-one derivatives of the present invention are those compounds of the general formula:

wherein X represents a halogen atom (preferably chlorine), R1, R2 and Rs have the same or different significances and each represents a hydrogen atom or an alkyl radical containing from 1 to 3 carbon atoms (preferably methyl), R4 represents a halogen atom (preferably chlorine), an alkyl radical containing from 1 to 3 carbon atoms (preferably methyl) or an alkoxy radical containing from 1 to 3 carbon atoms (preferably methoxy), and n represents zero or an integer from 1 to 4 inclusive. When n is 2,3 or 4 the substituents R4 may be the same or different.

The compounds of general formula I all possess at least one asymmetrically substituted carbon atom.

They can thus exist in several stereoisomeric forms and all such forms are within the scope of the present invention.

The 1 ,3,4-oxadiazoiin-5-one derivatives of general formula I possess useful insecticidal properties. They are particularly active by contact and by ingestion. Particularly valuable results are obtained by means of these compounds in the case of diptera, coleoptera and lepidoptera.

Preferred compounds are those of general formula I wherein the halogen atom represented by symbol X is attached to the para-position of the phenyl radical, and especially those such compounds wherein X represents a chlorine atom. Preferably R3 represents a hydrogen atom and n is zero or 1. Compounds of outstanding interest are 4-benzyl-l ,3,4-oxadiazolin-5-on-2-yl methyl 2-(4-chlorophenyl)-3-methyl butyrate and 1-(4-benzyl-1,3,4-oxadiazolin-5-on-2-yl)ethyl 2-(4-chlorophenyl)-3-methylbutyrate, especially its diastereoisomer having the physical characteristics: m.p. 40-45"C: [a]D = -21.3 (c = 10, acetone).

The first mentioned compound is especially important.

Certain oxadiazoie derivatives have already been described in the literature as having insecticidal properties. Thus United States Patent No. 4096273 (granted to A.D.Gutman) describes 3-benzyl-5-[2-(4 chlorophenyl)-3-methyl-butyryloxy-alkyl] ,2,4-oxadiazole compounds of the general formula:

(wherein R' represents a hydrogen atom or an alkyl radical containing from 1 to 4 carbon atoms and X' represents a hydrogen or chlorine atom) which are useful as insecticides.

The new 1,3,4-oxadiazolinone derivatives of the present invention are obviously different from the 1,2,4-oxadiazole derivatives disclosed in the aforementioned United States patent, and moreover exhibit -in the case of at least the most important compounds - a substantially greater insecticidal activity than the hitherto disclosed compounds.

The 1 ,3,4-oxadiazolin-5-one derivatives of general formula I are prepared, according to a feature of the present invention, by a process which comprises the the three following stages: Stage A. Reaction of an alkanoic acid derivative of the general formula:

(wherein Y and Y', which may have the same or different significances, each represent a chlorine atom or a hydroxy radical, with the proviso that when Y represents a hydroxy radical Y' does not represent a chlorine atom, and R, and R2 are as hereinbefore defined) with a benzylhydrazine derivative of the general formula:

(lV) (wherein Rs, R4 and n are as hereinbefore defined) in accordance with the reaction scheme:

wherein the various symbols are as hereinbefore defined.

Stage B. Cyclisation of the resulting hydrazine derivative of general formula V by reaction with phosgene in accordance with the reaction scheme:

wherein the various symbols are as hereinbefore defined.

Stage C. Reaction of the resulting 1,3,4-oxadiazolin-5-one derivative of general formula VI with a derivative of 2-phenyl-3-methylbutyric acid of the general formula:

(VII) (wherein Z represents the hydroxy radical or a chlorine atom and is different from Y defined above, and X represents a halogen atom) in accordance with the reaction scheme: (VI) + (Vll)^(l) + HCI in the presence of a base which serves as an HCI acceptor such as, for example, triethylamine, N,N-dimethylaniline or pyridine.

A preferred embodiment of the process hereinbefore described consists in using, as the starting material for the first stage of the process, an a-chloroalkanoic acid, or a chloride of such an acid, of the general formula:

wherein R1 and R2 are as hereinbefore defined, and Y' represents a hydroxy radical or a chlorine atom.

According to this preferred embodiment, stage A is then carried out in an inert organic solvent medium, such as an aromatic or aliphatic hydrocarbon, at a temperature approximately between 10 and 50"C. When compound VIII is an acid (Y'=OH), the water formed during this stage is removed by azeotropic distillation.

When compound VIII is an acid chloride (Y'=CI), the reaction is preferably carried out in the presence of an arylsulphonic or alkylsulphonic acid, such as methanesulphonic acid.

The cyclisation, according to stage B, of the compound thus obtained conforming to general formula V is carried out in an inert organic solvent medium, e.g. an aromatic hydrocarbon, at a temperature between 20 and 110".

According to stage C of the process, a 2-(chloroalkyl )-4-benzyl-1 ,3,4-oxadiazolin-5-one conforming to general formula VI resulting from stage B is reacted with an acid of the general formula:

(wherein X is as hereinbefore defined) in an inert organic solvent medium, such as an aromatic or aliphatic hydrocarbon, at a temperature approximately between 10 and 140"C.

According to another embodiment of the process hereinbefore described, an a-hydroxyalkanoic acid of the formula:

(wherein R1 and R2 are as hereinbefore defined) is used as the starting material for stage A and this stage is then carried out in an organic solvent medium at a temperature approximately between 80" and 1 508C, the water formed being removed by azeotropic distillation.

The cyclisation, according to stage B of the process, of the compound conforming to general formula V thus obtained is carried out in an aqueous medium at a temperature between 10 and 50"C.

According to stage C of the process, the 2-(hydroxyalkyl)-4-benzyl-1 ,3,4-oxadiazolin-5-one conforming to general formula VI then resulting from stage B is reacted with an acid chloride of the formula:

(wherein X is as hereinbefore defined) in an inert organic solvent medium, such as acetone, methylene chloride or an aromatic hydrocarbon, at a temperature approximately between 10 and 50"C.

The acids of formula IX are prepared in accordance with the method described in Beilstein 91, page 216, as for the preparation of 2-phenyl-3-methyl-butyric acid. 2-(4-Chlorophenyl)-3-methylbutyric acid is a known compound and is described in Chem. Abstr. 59, 1016e.

The acid chlorides of formula Xl are obtained in accordance with methods known perse by reaction of thionyl chloride with the corresponding acid of formula IX According to a variant of the process hereinbefore described, which variant also forms part of the invention, the 1,3,4-oxadiazolin-5-one derivatives of general formula I wherein R3 represents a hydrogen atom are also prepared in accordance with a process which comprises the following stages: Stage A 1. Reaction of the hydrazide of an a-hydroxyalkanoic acid of the general formula:

(wherein R1 and R2 are as hereinbefore defined) with a benzaldehyde derivative of the general formula:

(wherein R4 and n are as hereinbefore defined) to form a hydrazone of the benzaldehyde derivative in accordance with the reaction scheme::

wherein the various symbols are as hereinbefore defined. The reaction is advantageously carried out in an aqueous-alcoholic medium (e.g. a water/ethanol mixture) in the presence of acetic acid at a temperature approximately between 20 and 40"C.

Stage Bi. Reduction with hydrogen of the resulting hydrazone of general formula XIV in accordance with the reaction scheme:

wherein the various symbols are as hereinbefore defined. This reduction preferably takes place in the presence of palladium on charcoal at a temperature approximately between 20 and 60"C.

Stage Cl. Cyclisation of the resulting hydrazine derivative of general formula XV by reaction with phosgene to give a 1 ,3,4-oxadiazolin-5-one derivative of general formula:

wherein the various symbols are as hereinbefore defined. The cyclisation is advantageously carried out in an aqueous medium at a temperature between 10 and 50"C.

Stage Dl. Reaction of the resulting 1,3,4-oxadiazolin-5-one derivative of general formula XVI with a 2-phenyl-3- methylbutryric acid chloride of general formula Xl to give a compound of general formula I in accordance with the reaction scheme hereinbefore depicted in Stage C (Y in formula VI is the hydroxy radical and R3 in that formula is a hydrogen atom, and Z in formula VII is a chlorine atom). The reaction is carried out in the presence of a base which serves as an HCI acceptor and is preferably effected in an inert organic solvent medium, such as acetone, methylene chloride or an aromatic hydrocarbon, at a temperature approximately between 10 and 50"C.

The following Examples illustrate the preparation of 1,3,4-oxadiazolin-5-one derivatives of the present invention.

EXAMPLE 1 Preparation of 64benzyl- 1,3,4-oxadiazolin-5-on-2-ylJ-methyl 2-{4-chlorophenyl)-3-methylbutyrate (Corn- pound No. 1) A solution of 2-(4-chlorophenyl)-3-methyl-butyric acid chloride (9.2 g) in acetone (100 cc) is added dropwise, in the course of 10 minutes, to a solution of 2-hydroxymethyl-4-benzyl-l ,3,4-oxadiazolin-5-one (8.2 g) and triethylamine (4.04 g) in acetone (100 cc). The mixture is stirred for two hours at room temperature.

The precipitate formed is then removed by filtration on a glass frit and the organic solution is concentrated under reduced pressure. The residue is taken up in diisopropyl ether (250 cc) and the solution obtained is washed successively with water (200 cc), a 3.6% (w/v) aqueous hydrochloric acid solution (100 cc), a 4% (w/v) aqueous sodium hydroxide solution (100 cc) and water (100 cc).

After drying and concentrating under reduced pressure, the residue obtained is purified by chromatography on a silica column and gives (4-benzyl-1 ,3,4.oxadiazolin-5-on-2-yl)methyl 2-(4-chlorophenyl)-3methylbutyrate (12 g) melting at 70"C.

Elementary composition calculated found C % 62.92 62.76 H % 5.28 5.29 0% 15.97 15.78 N % 6.99 7.03 Cl % 8.84 9.0 2-(4-Chlorophenyl)-3-methylbutyric acid chloride is obtained by reaction of thionyl chloride with 2-(4-chlorophenyl)-3-methylbutyric acid, melting at 85 C, which is itesif prepared, in accordance with the method described in Beilstein 91 - page 216, by reaction of isopropyl bromide with (4-chlorophenyl)acetonitrile in the presence of sodamide and hydrolysis of the resulting product with sulphuric acid.

2-Hydroxymethyl-4-benzyl-1 ,3,4-oxadiazolin-5-one is prepared as follows: Benzylhydrazine (61 g) is reacted with glycolic acid (53 g) in solution in toluene (200 cc) at the reflux temperature. After azeotropic distillation of the water formed, the reaction mixture is taken up in water (500 cc). The aqueous layer is decanted and washed with methylene chloride (2 x 250 cc) and this aqueous layer is then re-introduced into a flask and saturated with phosgene at 20"C. The reaction mixture is taken up in methylene chloride (500 cc) and the organic layer is decanted and washed successively with a solution containing 100 g/l of potassium bicarbonate (500 cc) and then with distilled water (500 cc).After drying over sodium sulphate and concentrating under reduced pressure, 2-hydroxymethyl-4-benzyl-1 ,3,4-oxadiazolin-5- one (35 g), melting at 54"C, is obtained.

EXAMPLE 2 Preparation of l-(4-benzyl- l,3,4-oxadiazolln-5-on-2-yl)-ethyl 2-(4-chlorophenyll-3-methylbutyrate, in the form oftwo diastereoisomeric compounds A solution of 2-(4-chlorophenyl)-3-methylbutyric acid chloride (11.6 g) in methylene chloride (100 cc) is added rapidly to a solution of the L-isomer of 2-(1 -hydroxyethyl)4-benzyl-l ,3,4-oxadiazolin-5- one (11 g) in methylene chloride (50 cc), and pyridine (4 g) is then added dropwise in the course of 10 minutes. The reaction mixture is stirred for 2 hours at room temperature and is then taken up in a 3.5% (wlv) aqueous hydrochloric acid solution (300 cc).The organic layer is decanted, washed successively with a 10% (w/v) aqueous potassium bicarbonate solution (300 cc) and with water (300 cc), and dried.

After filtering, and concentrating under reduced pressure, the residue (weighing 22 g) is purified on a silica column. The oil (17 g) obtained after chromatography gives the following after trituration with petroleum ether: 1 -(4-benzyl-1 ,3,4-oxadiazolin-5-on-2-yI)ethyl 2-(4-chlorophenyl)-3-methylbutyrate (7 g), diastereoisomer A (Compound No.2), melting at 1020C, [alD = -39.6 (c = 10, acetone, and 1-(4-benzyl-1,3,4-oxadiazolin-59n- 2-yl)ethyl 2-(4-chlorophenyl)-3-methylbutyrate (9 g), diastereoisomer B (Compound No.3), in the form of a solid paste melting at 40-45"C, [alD = -21.3" (c= 10, acetone).

Elementary composition calculated found Compound Compound No.2 No.3 C % 63.69 63.69 63.26 H % 5.59 5.71 5.94 0% 15.42 15.60 14.91 N% 6.75 7.01 6.17 Cl % 8.55 8.45 8.85 The L-isomer of 2-(1 -hydroxyethyl)-4-benzyl-l ,3,4-oxadiazolin-5-one is obtained in accordance with the method described in Example 1 by reacting the L-isomer of lactic acid (33 g) with benzylhydrazine (25 g) in toluene heated to the reflux temperature and then cyclising the compound obtained with phosgene in an aqueous medium. This gives the L-isomer of 2-(1 -hydroxyethyl)-4-benzyl-1 ,3,4-oxadiazolin-5-one (18 g), melting at700C, [al20 = 19 (c = 10, acetone).

EXAMPLE 3 Following the same procedure as in Example 2, and with the same amounts of reactants, but starting with the D-isomer of 2-(1 -hydroxyethyl)-4-benzyl-1 ,3,4-oxadiazolin-5-one (prepared from the D-isomer of lactic acid), melting at 70"C [a]20 = + 19.7 (c = 10, acetone), there are obtained diastereoisomer C (Compound No.

4) (7 g), melting at [a]D = +42 (c = 10, acetone), and diastereoisomer D (Compound No. 5) (99), in the form of an oil, [a]0 = +22 (c = 10, acetone).

Elementary composition calculated found Compound Compound No.4 No.5 C % 63.69 63.89 63.90 H % 5.59 5.68 6.0 0% 15.42 15.26 15.40 N% 6.75 6.93 6.16 Cl % 8.55 8.44 9.31 EXAMPLE 4 Preparation of4-(2-meth ylbenzyl)- 1,3,4-oxa diazolin-5-on-2-yl]meth yl 2-(4-chlorophen yl)-3-meth ylbutyrate (Compound No. 6) A solution of 2-chloromethyl-4-(2-methylbenzyl)- 1,3A-oxadiazolin-5-one (13.3 g) in xylene (35 cc) is added in the course of 20 minutes to a solution of 2-(4-chlorophenyi)-3-methylbutyric acid (19 g) and triethylamine (11.7 cc) in xylene (175 cc) heated to 110 OC.The reaction mixture is heated at the reflux temperature for 4 hours and, after cooling, is washed successively with water (100 cc), a 3.5% (w/v) aqueous hydrochloric acid solution (100 cc), a 4% (w/v) aqueous sodium carbonate solution (100 cc) and water (100 cc). After drying, decolorising over animal charcoal and concentrating under reduced pressure, the residue obtained is purified by chromatography on a silica column and gives [4(2-methyl-benzyl)-1,3,4-oxadiazolin-5-on-2- yl]methyl 2-(4-chlorophenyl)-3-methylbutyrate (11.2 g) in the form of an oil.

Elementary composition calculated found C % 63.69 63.55 H % 5.59 5.78 0% 15.42 15.44 N% 6.75 6.88 Cl % 8.55 9.12 2-Chloromethyl-4-(2-methyl benzyl)-1 ,3,4-oxadiazolin-5-one is prepared as follows: Chloroacetyl chloride (d = 1.42: 56.7 cc) is reacted with 2-methylbenzhydrazine (100 g) in solution in toluene (1000 cc) in the presence of methanesulphonic acid (46.2 cc), at ambient temperature, and phosgene (200 g) is then introduced at a temperature between 25 and 112"C. The mixture is concentrated and 2-chloromethyl 4-(2-methylbenzyl)-1,3,4-oxadiazolin-5-one (13.3 g) is thus obtained in the form of an oil.

EXAMPLE 5 Preparation of J4-(2-chlorohenzyl)- 1,3,4-oxadiazolin-5-on-2-y/lmethy/ 2-(4-chlorophenyl)-3-meth ylbutyrate (Compound No. 7) Following the procedure of Example 1 but starting with a solution of 2-hydroxymethyl-4-(2-chlorobenzyl)1,3,4-oxadiazolin-5-one (16 g) in acetone (100 cc) and a solution of 2-(4-chlorophenyl)-3-methyl-butyric acid (17.8 g) in acetone (50 cc), [4-(2-chlorobenzyl)-1,3,4-oxadiazolin-5-on-2-yl]methyl 2-(4-chlorophenyl)-3- methylbutyrate (26 g) is obtained in the form of an oil.

Elementary composition calculated found C % 57.94 58.61 H % 4.63 4.68 0% 14.70 13.94 N% 6.44 6.15 CI% 16.29 16.31 2-Hydroxymethyl-4-(2-chlorobenzyl)-1 ,3,4-oxadiazolin-5-one is obtained by reaction of phosgene with a solution of 1-(2-chlorobenzyl)-2-glycolyl-hydrazine (38 g) in water (600 cc) at a temperature between 20 C 30 C.

In this way, after recrystallisation from diisopropyl ether, 2-hydroxymethyl-4-(2-chlorobenzyl)- 1,3,4oxadiazolin-5-one (16 g) melting at 67C is obtained (yield 42%).

1 -(2-Chlorobenzyl)-2-glycolyl-hydrazine is prepared by reducing 2-chlorobenzaldehyde glycolylhydrazone (41.5 g), dissolved in dioxan (415 cc), with hydrogen in the presence of palladium on charcoal in an autoclave, under hydrogen at a pressure of 15 kg/cm2, at a temperature between 20 and 60"C. After filtration and concentration,2-hydroxymethyl-4-(2-chlorobenzyl)-1,3,4-oxadiazolin-5-one (38 g) is obtained.

2-Chlorobenzaldehyde glycolylhydrazone (41.5 g), melting at 166 C, is itself obtained by reaction of glycolylhydrazine (18 g) with 2-chlorobenzaldehyde (30.9 g) dissolved in a mixture of water (20 cc). acetic acid (10 cc) and ethanol (60 cc), at a temperature between 20 and 40 C.

After precipitation and cooling, the product is filtered off, washed with water and alcohol, and dried.

[4-(2-Chlorobenzyl)-1 3,4-oxadiazol in-5-on-2-yl]methyl 2-(4-chlorophenyl )-3-methyl butryrate (41.5 g) is thus obtained.

EXAMPLE 6 The following compounds were prepared from suitable starting materials by employing the method described in Example 4.

Compound No.

8 4-(4-Chlorobenzyl )-1 ,3,4-oxadiazolin-5-on-2-yI methyl 2-(4-chlorophenyl)-3-methylbutyrate 9 2-(4-Benzyl-1 ,3,4-oxadiazolin-5-on-2-yl)-prop-2-yl 2-(4-chlorophenyl )-3-methylbutyrate 10 4-(2-Methoxybenzyl)-1,3,4-oxadiazol in-5-on-2-yI methyl 2-(4-chlorophenyl)-3-methyl butyrate 11 4-(4-Methylbenzyl)-1,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl)-3-methylbutyrate 12 4-(3-Methylbenzyl)-l ,3,4-oxadiazolin-5-on-2-yl methyl 2-(4-chlorophenyl)-3-methylbutyrate 13 4-(3-Methoxybenzyl)-1,3,4-oxadiazolin-5-on-2-ymethyl 2-(4-chlorophenyl)-3-methylbutyrate 14 4-(3.Chlorobenzyl )-1 3,4-oxadiazo lin-5-on-2-ylmethyl 2-(4-chlorophenyl )-3-methylbutyrate Compound Physical Elementary composition No. characteristic calculated found 8 oil C % 57.94 58.54 H % 4.63 4.85 0% 14.70 14.80 Cl % 16.29 15.80 N % 6.44 6.29 9 m.p. 85"C C % 64.41 63.86 H % 5.87 5.87 0% 14.92 14.91 Cl % 8.27 8.98 N% 6.53 6.04 10 oil C% 61.32 62.90 H % 5.38 5.65 0% 18.57 18.17 Cl % 8.23 7.70 N% 6.50 5.90 11 oil C % 63.69 63.22 H % 5.99 5.48 0% 15.42 14.81 Cl % 8.55 9.25 N% 6.75 7.18 12 oil C % 63.69 62.50 H % 5.59 5.40 0% 15.42 15.02 Cl % 8.55 10.02 N % 6.75 7.70 13 oil C% 61.32 61.76 H % 5.38 5.37 0% 18.57 18.0 Cl % 8.23 6.50 N% 6.50 6.0 14 oil C % 57.94 58.20 H % 4.63 4.64 0% 14.70 14.12 Cl % 16.29 16.70 N % 6.44 6.28 The insecticidal activity of the 1,3,4-oxadiazolin-5-one derivatives of the present invention is demonstrated by the results obtained in the following tests::- (a) Contact-insecticidal activity (flies and flour beetles) An acetone solution or suspension (1 cc) containing a given concentration of the product to be studied is introduced into a 120 cc glass pot and four pots are prepared in this way for each concentration of the product to be studied. When the solvent has evaporated off, either 5 flies (Musca domestica) or 10 flour beetles (Tribolium confusum) are introduced into each of the pots. For each concentration of the product to be studied, two pots are used per species of insect. The pots are covered with a wire mesh and the number of dead insects after 24 hours' contact, in the case of the flies, and after 3 days' contact, in the case of the flour beetles, is counted. The concentration which causes the death of 90% of the insects, hereafter referred to as Ciso is thus determined. The results observed are shown in the table below, in which the Cl90) values are expressed in mg per cc, taking 3-benzyl-5-[2-(4-chlorophenyl )-3-methylbutyryloxy-methyl]-l ,2,4-oxadiazole, the product of Example II of United States Patent No. 4096273, as the comparison product.

Compound Flies Flour beetles No. Cigo Clgo 1 10 100 3 30 300 5 100 6 100 11 200 12 100 13 1000 Comparison compound 30 1000 (b) Insecticidal activity by contact-ingestion (leaves treated by dipping and exposed to caterpillars of Plutella maculipennis and caterpillars of Pieris brassicae) An emulsifiable solution having the following composition is prepared:: 250g active material to be tested 250g emulsifier (a mixture of calcium phenylsulphonate and of oxyethyleneated nonylphenol 90 g surface-active agent (monolaurate of oxyethyleneated sorbitan) 20 g solvent (mixture of 2 volumes of acetophenone and 3 volumes of toluene) q.s.p 1000 cc The solution thus obtained is then diluted with distilled water containing 0.02% of the same surface-active agent so as to give several solutions of a definite concentration.

Young leaves of broccoli (Brassica o/eracea) at the four-leaf stage are dipped for 10 seconds in the solutions to be studied. The leaves are allowed to dry and when they are dry they are spread in cylindrical plastic boxes. 10 Caterpillars (3rd stage) of Plutella maculipennis or of Pieris brassicae are placed in each box. For each species of caterpillar, two boxes are used per concentration of active material.

After 3 days, the living caterpillars and the dead caterpillars are counted for each concentration of active material, and the concentration which results in the death of 50% of the caterpillars (Clso) is determined. The results observed are shown in the following Table in which the Clso are expressed in mg per cc.

Compound Plutella Pieris No. (Cl50) (Cl50) 1 20 100 2 1000 1000 3 100 300 5 1000 8 1000 10 2000 2000 11 2000 12 1000 2000 13 300 1000 Comparison product 300 500 For use in practice as insecticides, the compounds of general formula I are rarely used by themselves. Most frequently, they form a component of compositions which generally comprise a carrier and/or a surface-active agent compatible with the active compound(s) and suitable for use in agricultural compositions. In these insecticidal compositions, the content of active compound generally varies from 0.05% by weight to 95% by weight.

The term "carrier" in the sense of the present description denotes an organic or inorganic, natural or synthetic, material with which the active ingredient is associated in order to facilitate its application to the plant, to seeds or to the soil, or to facilitate its transportation or its handling. The carrier can be solid (e.g.

clays, natural or synthetic silicates, calcined magnesia, kieselguhr, tricalcium phosphate, cork powder, absorbent charcoal, resins, waxes and solid fertilisers) or fluid (e.g. water, alcohols, ketones, petroleum fractions, chlorinated hydrocarbons and liquified gases).

The surface-active agent can be an emulsifying agent, dispersing agent or wetting agent, each of which can be ionic or non-ionic. As examples there may be mentioned salts of polyacrylic acids or ligninsulphonic acids, sulphoricinoleates, quaternary ammonium salts, ethylene oxide condensates with fatty alcohols, fatty acids, or fatty amines and, in particular; products based on ethylene oxide condensates, such as condensates of ethylene oxide with octyl- or nonyl-phenol, or esters of fatty acids an anhydrosorbitols which have been rendered soluble by etherification of the free hydroxy radicals by condensation with ethylene oxide. It is preferable to use agents of the non-ionic type because they are not sensitive to electrolytes.

The compositions according to the invention can be prepared in the form of wettable powders, dusting powders, granules, solutions, suspensions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols.

The wettable powders are usually prepared in such a way that they contain from 20 to 95% by weight of active ingredient, and contain, in addition to a solid carrier, from 1 to 10% by weight of a wetting or dispersing agent and, where necessary, from 0 to 10% by weight of one or more stabilisers and/or other additives, such as penetrating agents, adhesives, anti-caking agents or dyestuffs.

- By way of example, the following is the composition of a wettable powder, the percentages being expressed by weight: EXAMPLE 7 active ingredient (Compound No.6) 50 9 calcium lignosulphonate (deflocculating agent) 5% isopropyinaphthalenesulphonate (wetting agent) 1% anti-caking silica 5% filler (kaolin) 39 % The dusting powders are usually prepared in the form of a dust concentrate which has a composition similar to that of a wettable powder, but without a wetting or dispersing agent. They can be diluted on site by means of a supplementary amount of a fluid carrier, so that a composition is obtained which can easily coat seeds to be treated and which usually contains from 0.5 to 10% by weight of active material.

By way of example, the following is the composition of a dusting powder: EXAMPLE 8 active ingredient (Compound No. 6) 50 % anionic wetting agent 1% anti-caking silica 6% kaolin (filler) 43 % Granules, which are intended to be scattered on the ground, are usually prepared so that they have dimensions of between 0.1 and 2 mm, and can be manufactured by agglomeration or by impregnation. In general, the granules contain from 0.5 to 25% of active ingredient, and from 2 to 20% by weight/volume of suitable additives, such as stabilisers, modifiers which ensure slow liberation, binders and solvents.

The emulsifiable concentrates which can be applied by spraying usually contain a solvent, a co-solvent where necessary, from 10 to 50% by weight/volume of active ingredient, from 2 to 20% weight/volume of an emulsifying agent, and from 2 to 20 by weight/volume of suitable additives, such as stabilisers, penetrating agents, corrosion inhibitors, dyestuffs and adhesives.

By way of example, the following is the composition of an emulsifiable concentrate, the amounts being expressed in g/litre: EXAMPLE 9 active ingredient (Compound No.6) 400 g/l dodecylbenzenesulphonate 24g/l nonylphenol oxyethyleneated with 10 molecules of ethylene oxide 16 gel cyclohexanone 200 g/l aromatic solvent q.s.p 1 litre Aqueous dispersions and emulsions, e.g. compositions obtained by diluting a wettable powder or an emulsifiable concentrate according to the invention with water, are included within the general scope-of the present invention. Such emulsions can be of the water-in-oil type or of the oil-in-water type and can have a thick consistency such as that of a "mayonnaise".

For so-called "ultra-low volume" application with a spray of very fine droplets, solutions in organic solvents containing from 70 to 99% of active ingredient are prepared.

The insecticidal compositions according to the invention can contain other ingredients, e.g. protective colloids, adhesives or thickeners, as well as other known active substances possessing pesticidal properties, in particular insecticidal or fungicidal properties.

Claims (39)

1. 1 ,3,4,-Oxadiazolin-5-one derivatives of the general formula:

wherein X represents a halogen atom, R1, R2 and R3 have the same or different significances and each represents a hydrogen atom or an alkyl radical containing from 1 to 3 carbon atoms, R4 represents a halogen atom, an alkyl radical containing from 1 to 3 carbon atoms or an alkoxy radical containing from 1 to 3 carbon atoms, and n represents zero or an integer from 1 to 4 inclusive.

2. 1,3,4-Oxadiazolin-5-one derivatives according to claim 1 wherein R3 represents a hydrogen atom

3. 1 ,3,4-Oxadiazolin-5-one derivatives according to claim 2 wherein n represents zero.

4. 1,3,4-Oxadiazolin-5-one derivatives according to claim 1 or 2 wherein n represents 1.

5. 1,3,4-Oxadiazolin-5-one derivatives according to any one of the preceding claims wherein the halogen atom represented by symbol X is in the para-position of the phenyl radical.

6. 1 ,3,4-Oxadiazolin-5-one derivatives according to claim 5 wherein X represents a chlorine atom in the para-position of the phenyl radical.

7. 1,3,4-Oxadiazolin-5-one derivatives according to any one of the preceding claims wherein R1 and/or R2 represents a hydrogen atom or a methyl radical.

8. 1,3,4-Oxadiazolin-5-one derivatives according to claim 2,4,5,6 or 7 wherein R4 represents a chlorine atom, or a methyl or methoxy radical, and n represents 1.

9. 4-Benzyl-1 ,3,4-oxadiazol in-5-on-2-ylmethyl 2-(4-chlorophenyl)-3-methylbutyrate.

10. 1 -(4-Benzyl-1 ,3,4-oxadiazolin-5-on-2-yl)ethyl 2-(4-chlorophenyl)-3-methylbutyrate.

11. The diastereoisomer of 1 -(4-benzyl-1 ,3,4-oxadiazolin-5-on-2-yl)ethyl 2-(4-chlorophenyl)-3-methylbutyrate having a melting point of 40-45"C and [a]20 = -21.3 (c = 10, acetone).

12. 4-(2-Methylbenzyl)-1 ,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl )-3-methylbutyrate.

13. 4-(2-Chlorobenzyl)-1 3,4-oxadiazoli n-5-on-2-yl methyl 2-(4-ch lorophenyl)-3-methylbutyrate.

14 4-(4-Chlorobenzyl )-1 ,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl)-3-methylbutyrate.

15. 2-(4-Benzyl-1 3,4-oxadiazol in-5-on-2-yl)-prop-2-yl 2-(4-chlorophenyl )-3-methyl butyrate.

16. 4-(2-Methoxybenzyl)-1 ,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl)-3-methylbutyrate.

17. 4-(4-Methylbenzyl)-1 ,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl )-3-methylbutyrate.

18. 4-(3-Methyl benzyl)-1 ,3,4-oxadiazolin-5-on-2-yl methyl 2-(4-chlorophenyl)-3-methylbutyrate.

19. 4-(3-Methoxybenzyl)-1 ,3,4-oxadiazolin-5-on-2-ylmethyl 2-(4-chlorophenyl)-3-methylbutyrate.

20. 4-(3-Chlorobenzyl )-1,3,4-oxadiazol methyl 2-(4-chlorophenyl)-3-methylbutyrate.

21. Process for the preparation of a 1 ,3,4-oxadiazolin-5-one derivative as claimed in claim 1 which comprises the reaction of an alkanoic acid derivative of the general formula:

(wherein Y and Y', which may have the same or different significances, each represent a chlorine atom or a hydroxy radical, with the proviso that when Y represents a hydroxy radical Y' does not represent a chlorine atom, and R1 and R2 as defined in claim 1) with a benzylhydrazine derivative of the general formula:

(wherein R3, R4 and n are as defined in claim 1) to give a hydrazine derivative of the general formula:

(wherein Y is as hereinbefore defined, and the other symbols are as defined in claim 1), cyclisation of the hydrazine derivative of general formula V by reaction with phosgene to give a compound of the general formula::

(wherein Y is as hereinbefore defined, and the other symbols are as defined in claim 1), and reaction of the 1,3,4-oxadiazolin-5-one derivative of general formula VI with a derivative of 2-phenyl-3-methylbutyric acid of the general formula:

(wherein Z represents the hydroxy radical or a chlorine atom with the proviso that Z is different from Y defined above, and X represents a halogen atom) in the presence of a base to give a 1,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1.

22. Process according to claim 21 in which the reaction between the compounds of general formulae VI and VII is carried out in the presence of triethylamine, N,N-dimethylaniline or pyridine.

23. Process for the preparation of a 1 ,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1 wherein R3 represents a hydrogen atom and the other symbols are as defined in claim 1 which comprises the reaction of the hydrazide of an a-hydroxyalkanoic acid of the general formula:

(wherein R1 and R2 are as defined in claim 1) with a benzaldehyde derivative of the general formula:

(wherein R4 and n are as defined in claim 1) to form a hydrazone of the benzaldehyde derivative of the general formula:

(wherein the various symbols are as defined in claim 1), reduction with hydrogen of the hydrazone of general formula XIV to give a compound of the general formula::

wherein the various symbols are as defined in claim 1), cyclisation of the hydrazine derivative of general formula XV by reaction with phosgene to give a 1,3,4-oxadiazolin-5-one derivative of the general formula:

(wherein the various symbols are as defined in claim 1), and reaction of the 1,3,4-oxadiazolin-5-one derivative of general formula XVI with a 2-phenyl-3-methylbutyric acid chloride of the general formula:

(wherein X is as defined in claim 1) to give a 1 ,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1 wherein Rs represents a hydrogen atom.

24. Process for the preparation of a 1 ,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1 substantially as hereinbefore described with especial reference to Example 1,2, or 3.

25. Process for the preparation of a 1,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1 substantially as hereinbefore described in Example 4, 5, or 6.

26. 1,3,4-oxadiazolin-5-one derivatives of the general formula specified in claim 1 when prepared by a process claimed in claim 21,22, 23, 24 or 25.

27. Insecticidal compositions which comprise, as active ingredient, at least one 1,3,4-oxadiazolin-5-one derivative as claimed in any one of claims 1 to 20 in association with at least one carrier and/or surface-active agent compatible with the said compound(s) and suitable for use in agricultural insecticidal compositions.

28. Insecticidal compositions according to claim 27 in which a carrier is water.

29. Insecticidal compositions according to claim 27 or 28 in which the quantity of oxadiazolinone derivative is from 0.05% to 95 by weight of the composition.

30. Insecticidal compositions according to claim 27 in the form of a wettable powder which comprises from 20% to 95% of oxadiazolinone derivative, a solid carrier therefor, from 1 to 10% of a wetting or dispersing agent and from 0 to 10% of one or more stabilizers and/or other additives, the said percentages being by weight.

31. Insecticidal compositions according to claim 27 in the form of a dust concentrate which comprises from 20% to 95% of oxadiazolinone derivative, a solid carrier therefor, and from 0 to 10% of one or more stabilizers and/or other additives, the said percentages being by weight.

32. Insecticidal compositions according to claim 27 in the form of granules of size between 0.1 and 2 mm containing from 0.5% to 25% by weight of oxadiazolinone derivative and from 2 to 20% by weight/volume of suitable additives.

33. Insecticidal compositions according to claim 27 in the form of an emulsifiable concentrate which comprises from 10% to 50% of oxadiazolinone derivative, an organic solvent therefor, from 2% to 20% of an emulsifying agent, and from 2 to 20% of appropriate additives, the said percentages being weight/volume.

34. Insecticidal compositions according to claim 27 in which the surface-active agent is a non-ionic compound.

35. Insecticidal compositions according to claim 27 which include another pesticide compatible with the oxadiazolinone derivative(s) and with the carrier and/or surface-active agent.

36. Insecticidal compositions according to claim 27 substantially as hereinbefore described with especial reference to Example 7,8 or 9.

37. The use of a 1,3,4-oxadiazolin-5-one derivative of the general formula specified in claim 1 as an insecticide.

38. A compound of the general formula:

wherein Y represents a chlorine atom or a hydroxy radical, and the other symbols are as defined in claim 1.

39. A comoound of the aeneral formula:

wherein Y represents a chlorine atom or a hydroxy radical, and the other symbols are as defined in claim 1.