WO1994027972A1

WO1994027972A1 - Substituted pyrazolines having insecticidal and acaricidal activity

Info

Publication number: WO1994027972A1
Application number: PCT/EP1994/001693
Authority: WO
Inventors: Andreas Van Almsick; Annegrit Bosum-Dybus; Holger Hoffmann; Thomas Wegmann; Hartmut Joppien; Harald Von Keyserlingk
Original assignee: Schering Aktiengesellschaft
Priority date: 1993-05-27
Filing date: 1994-05-25
Publication date: 1994-12-08
Also published as: DE4318938A1; ZA943753B; IL109678A0; AU6996794A; AP9400644A0

Abstract

Substituted pyrazoline derivatives of general formula (I) in which R?1, R2 and R4¿, which may be the same or different, are hydrogen, or are phenyl, cycloalkyl, cycloalkenyl, alkyl, alkoxycarbonyl, alkylcarbonyl or alkenyl, each of which is optionally substituted, or R?1 and R2¿ together form an optionally benzo fused alkylene group, R?3 and R5¿, which may be the same or different, are hydrogen or optionally substituted alkyl, R?6, R7 and R8¿, which may be the same or different are hydrogen, nitro or cyano or are phenyl, cycloalkyl, cycloalkenyl, alkyl, alkoxy, alkylthio, alkoxycarbonyl, alkylcarbonyl or alkenyl, each of which is optionally substituted, or R?6 and R7¿ together with the C-C double bond attached to the nitrogen form an optionally substituted cycloalkenyl ring, have insecticidal and acaricidal activity.

Description

SUBSTITUTED PYRAZOLINES HAVING INSECTICIDAL AND ACARICIDAL ACTIVITY

Field of the invention

This invention relates to new substituted pyrazoline derivatives with an enamide structure, processes for their preparation, as well as their use as pesticides,

especially as insecticides and acaricides.

Prior Art

Pyrazolines with insecticidal activity are already well known. There are a number of patents describing such compounds. In particular a number of patent applications, e.g. EP 227 055 and DE 4 005 114, disclose pyrazolines which have a carbamoyl structure at the 1-position.

The disadvantage of many of the prior art compounds is the insufficient activity and/or spectrum and/or have an unacceptable toxicity to mammals or beneficial insects and/or mites. We have now found that the novel group of compounds of the present invention overcome these

disadvantages. Description of the Invention

According to the invention there is provided a pyrazoline derivative of general formula I

in which

R¹, R² and R⁴, which may be the same or different, are

hydrogen, or are phenyl, cycloalkyl, cycloalkenyl, alkyl, alkoxycarbonyl, alkylcarbonyl or alkenyl, each of which is optionally substituted,

or R¹ and R² together form an optionally benzo fused

alkylene group,

R³ and R⁵, which may be the same or different, are hydrogen or optionally substituted alkyl,

R⁶, R⁷ and R⁸, which may be the same or different are

hydrogen, nitro or cyano or are phenyl, cycloalkyl, cycloalkenyl, alkyl, alkoxy, alkylthio,

alkoxycarbonyl, alkylcarbonyl or alkenyl, each of which is optionally substituted, or

R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form an optionally substituted cycloalkenyl ring.

The invention includes isomeric forms and as well as mixtures of isomers.

Particularly preferred compounds of formula I are those where

R¹, R² and R⁴, which may be the same or different, are

hydrogen, or are phenyl, optionally substituted by one or more of the same or different, halogen, nitro, cyano, C_1-6-alkyl, C_1-6-alkoxy,

C_1-6-alkoxycarbonyl, C_1-6-alkylthio, halo-C_1-6-alkyl, halo-C_1-6-alkoxy, halo-C_1-6-alkoxycarbonyl, halo- C_1-6-alkylthio, C_1-6-alkylsulfonyl or

halo-C_1-6-alkylsulfonyl, or are C_5-8-cycloalkyl or C_5-8-cycloalkenyl, each of which is optionally substituted by one or more of the same or different, cyano, C_1-6-alkyl, halo-C_1-6-alkyl, C_1-6-alkoxy, halo-C_1-6-alkoxy, C_1-6-alkylthio, halo-C_j.6-alkylthio, C_1-6-alkoxycarbonyl or halσ-C_1-6-alkoxycarbonyl, or are C_1-6-alkyl, C_1-6-alkoxycarbonyl, C_1-6-alkylcarbonyl or C_1-6-alkenyl, each of which is optionally substituted by halogen, nitro or cyano,

R³ and R⁵, which may be the same or different, are hydrogen or C_1-6-alkyl, optionally substituted by halogen, nitro or cyano,

R⁶, R⁷ and R⁸, which may be the same or different are

hydrogen, nitro or cyano or are phenyl, optionally substituted by one or more of the same or different, halogen, nitro, cyano, C_1-6-alkyl, C_1-6-alkoxy,

C_1-6-alkoxycarbonyl, C_1-6-alkylthio, halo-C_1-6-alkyl, halo-C_1-6-alkoxy, halo-C_1-6-alkoxycarbonyl, halo- C_1-6-alkylthio, C_1-6-alkylsulfonyl or halo- C_1-6-alkylsulfonyl, or are C_5-8-cycloalkyl or

C_5-8-cycloalkenyl, each of which is optionally

substituted by one or more of the same or different, cyano, C_1-6-alkyl, halo-C_1-6-alkyl, C_1-6-alkoxy, halo- C_1-6-alkoxy, C_1-6-alkylthio, halo-C_1-6-alkylthio,

C_{1 -6}-alkoxycarbonyl or halo-C_1-6-alkoxycarbonyl , or are C_1-6-alkyl , C_1-6-alkoxycarbonyl , C_1-6-alkylcarbonyl or C_1-6-alkenyl , each of which is optionally substituted by halogen , nitro or cyano , or

R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form a C_5-8-cycloalkenyl ring , optionally substituted by one or more of the same or different , halogen , cyano , C_1-6-alkyl , C_1-6-alkoxy , C_1-6-alkylthio , C_1-6-alkoxycarbonyl , halo-C_1-6-alkyl , halo-C_1-6-alkoxy , halo-C_1-6-alkylthio or halo-C_1-6-alkoxycarbonyl ,

C_1-6-alkylsulfonyl .

Preferably at least one of R¹ , R² and R⁴ , is optionally substituted phenyl and it is particularly preferred that both R¹ and R² are optionally substituted phenyl. R⁴ is preferably hydrogen.

Particularly preferred substituents on these R¹ and R² phenyls are halogen, cyano or halo-C_1-6-alkoxy.

For the moiety in the 1-position of the pyrazoline, it is generally preferred that R⁸ is hydrogen and either R⁶ is hydrogen, in which case R⁷ is optionally substituted phenyl, in which the substituents are preferably halogen, nitro, cyano, C_1-6-alkyl, C_1-6-alkoxy, halo-C_1-6-alkyl or halo-C_1-6-alkoxy, or R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form an optionally

substituted C_5-8-cycloalkenyl ring, preferably a

cyclohexenyl ring, in which the substituents are

preferably halogen, cyano, C_1-6-alkyl, C_1-6-alkoxy, halo-C_1-6-alkyl or halo-C_1-6-alkoxy, and especially C_1-6-alkyl, or halo-C_1-6-alkyl. It is preferred that R³, R⁴ and R⁵, are all hydrogen,

By the term "halogen" it is preferably understood to mean fluorine, chlorine or bromine. Particularly preferred are compounds of formula I in which R¹ is 4-cyanophenyl, 4-fluorophenyl, 4-chlorophenyl,

4-isopropoxyphenyl, 4-butoxyphenyl or

4-(2,2,2-trifluoroethoxy)phenyl,

R² is 4-cyanophenyl, 4-fluorophenyl- or

4-chlorophenyl or 4-isopropoxyphenyl,

R³, R⁴, R⁵ and R⁸ are hydrogen, and either

a) R⁶ is hydrogen and R⁷ is 4-trifluoromethylphenyl,

3-trifluoromethylphenyl, 4-nitrophenyl- 4-trifluoromethoxyphenyl, 3-trifluoromethoxyphenyl, b) R⁶ and R⁷ together with the C-C double bond on the nitrogen form cyclohex-1-enyl, 4-methylcyclohex- 1-enyl or 4-trifluoromethylcyclohex-1-enyl.

The pyrazoline derivatives of the invention of general formula I, can be prepared by reacting a pyrazoline derivative of general formula II

in which R¹, R², R³, R⁴ and R⁵ have the meanings given above, with an isocyanate of general formula III

in which R⁶, R⁷ and R⁸ have the meanings given above, optionally in the presence of a base.

For example if one uses 3,4-bis-(4-chlorophenyl)-2-pyrazoline and 4-trifluoromethylcyclohex-1-enyl isocyanate as starting materials, the reaction can be illustrated as follows.

The pyrazoline derivatives of general formula II are known or can be obtained in known manner, for example as

described in J. Agric. Food Chem. Vol. 25, No. 5, (1977) 987, J. Agric. Food Chem. Vol. 27, No. 2, (1979), 406, J. Agric. Food Chem. Vol. 26, No. 4, (1973), 915; USP

4,439,440; EP-A 113 213; EP-A 053 424, USP 4,663,341, DE-A 3 628 647 or EP-A 236 346.

The isocyanates of general formula III are known or can be obtained in known manner, for example as described in J. Org. Chem. 49, (1984), 4569-4571.

Those compounds of formula III where R⁶ and R⁷ together with the C-C double bond on the nitrogen form a

cyclohexenyl ring, substituted by halo-C_1-6-alkyl, halo-C_1-6- alkoxy, halo-C_1-6-alkylthio, C_1-6-alkoxycarbonyl or halo- C_1-6-alkoxycarbonyl, are new and form part of the

invention. In these cases some of the precursors may also be novel and also form part of the invention.

Particular novel compounds that can be mentioned are :

4-trifluoromethylcyclohex-1-enyl isocyanate , the mixed anhydride from

4-trifluoromethylcyclohex-1-enecarboxylic acid and ethyl hydrogen carbonate,

4-trifluoromethylcyclohex-1-enecarbonyl chloride, 4-trifluoromethylcyclohex-1-enecarbonyl azide,

4-trifluoromethylcyclohex-1-enecarboxylic acid, 4-trifluoromethyleyclohex-1-enecarbonitrile,

1-hydroxy-4-trifluoromethylcyclohexane- 1-carbonitrile and

4-trifluoromethyl-1-trimethyIsilyloxycyclohexane- 1-carbonitrile.

In some situations the isocyanate can be formed in situ and in these cases it may be possible to use the so formed isocyanate in the next reaction stage without isolation and/or purification.

The reaction between the compounds of formula II and formula III is preferably carried out in an organic solvent or mixture of solvents at a temperature of from -20 to 150°C, preferably at 20 to 90°C.

Suitable solvent are liquids which are inert to the reactants, e.g aliphatic, alicyclic or aromatic

hydrocarbons, which are optionally chlorinated, e.g.

pentane, hexane, cyclohexane, petroleum ether, benzene, toluene, xylene, dichloromethane, chloroform, carbon tetrachloride, ethylene dichloride, trichloroethylene or chlorobenzene; ethers, such as diethyl ether, methyl ethyl ether, diisopropyl ether, dibutyl ether, methyl tert-butyl ether, dioxane or tetrahydrofuran; nitriles, such as acetonitrile, propionitrile or benzonitrile; esters, such as ethyl acetate or amyl acetate; amides, such as

dimethylformamide; N-methylpyrrolidone or

hexamethylphosphoric triamide, as well as sulfones, such as dimethyl sulfoxide or sulfolane. As bases there can mentioned aliphatic, aromatic and heterocyclic amines, e.g. triethylamine, dimethylaniline or pyridine. The reaction can be carried out at atmospheric pressure although higher or lower pressures may be used.

The compounds of the invention prepared by these processes can be isolated from the reaction mixtures in conventional manner, for example by distillation of the solvent at normal or reduced pressure, by precipitation with water or by extraction. A higher level of purity can be achieved as a rule by column chromatography or recrystallisation. Besides the process described, compounds of formula I may also be obtained by reacting a pyrazoline derivative of general formula IV

in which R¹, R², R³, R⁴ and R⁵ have the meanings given above, with a carbonyl compound of general formula V

or an enol ether of general formula VI

in which R⁶, R⁷ and R⁸ have the meanings given above, and R⁹ is C_1-6-alkyl, optionally in the presence of an acid.

The compounds of the invention have insecticical and acaricidal activity and are suitable for combating

parasites of humans and domestic animals as well as plant pests. Examples are Lepidoptera, such as Plutella

xylostella , Spodoptera littoralis, Heliothis armigera, Heliothis virescens and Pieris brassicae ; Diptera, such as Gasterophilus, Cochliomyia, Muεca domestica , Ceratitis capitata , Erioischia braεεicae , Lucilia sericata and Aedes aegypti ; Hemiptera, including aphids such as Megoura viciae and leafhoppers, such as Nilaparvata lugens and Nephotettix cincticeps; Coleoptera, such as Phaedon

cochleariae, Anthonoiπuε grandis and corn rootworms

(Diabrotica spp., e.g. Diabrotica undecimpunctata);

Orthoptera, such as Blatiella germanica ; ticks, such as Boophilus microplus and lice, such as Damalinia bovis and Linognathus vituli as well as mites such as Tetranychus urticae and Panonychus ulmi . The compounds of the invention can be used either alone or in mixture with each other or another insecticide.

Optionally other plant protection or pesticidal

compositions, such as for example insecticides, acaricides or fungicides can be added depending on the desired

result. An improvement in the intensity and speed of action can be obtained, for example, by addition of suitable adjuvants, such as organic solvents, wetting agents and oils. Such additives may allow a decrease in the dose.

Suitable mixture partners may also include phospholipids, e.g. such as from the group phosphatidylcholine, hydratεd phosphatidylcholine, phosphatidylethanolamine,

N-acyl-phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, lysolecithin or phosphatidylglycerol.

The designated active ingredients or their mixtures can suitably be used, for example, as powders, dusts,

granules, solutions, emulsions or suspensions, with the addition of liquid and/or solid carriers and/or diluents and, optionally, binding, wetting, emulsifying and/or dispersing adjuvants.

Suitable liquid carriers are, for example aliphatic and aromatic hydrocarbons such as benzene, toluene, xylene, cyclohexanone, isophorone, dimethyl sulfoxide,

dimethylformamide, other mineral-oil fractions and plant oils. Suitable solid carriers include mineral earths, e.g.

tonsil, silica gel, talcum, kaolin, attapulgite,

limestone, silicic acid and plant products, e.g. flours.

As surface-active agents there can be used for example calcium lignosulfonate, polyoxyethylenealkylphenyl ether, naphthalenesulfonic acids and their salts, phenolsulfonic acids and their salts, formaldehyde condensates, fatty alcohol sulfates, as well as substituted benzenesulfonic acids and their salts.

The percentage of the active ingredient ( s ) in the various preparations can vary within wide limits. For example, the compositions can contain about 10 to 90 percent by weight active ingredients, and about 90 to 10 percent by weight liquid or solid carriers, as well as, optionally up to 20 percent by weight of surfactant.

The agents can be applied in customary fashion, for example with water as the carrier in spray mixture volumes of approximately 100 to 1,000 1/ha. The agents can be applied using low-volume or ultra-low-volume techniques or in the form of so-called microgranules.

The preparation of these formulations can be carried out in known manner, for example by milling or mixing

processes. Optionally, individual components can be mixed just before use for example by the commonly used so-called tank-mixing method.

Formulations can be prepared, for example, from the following ingredients.

A1 WETTABLE POWDER

30 percent by weight active ingredient

15 percent by weight kaolin

5 percent by weight of surfactant based on

of the sodium salt of N-methyl-N-oleyltaurine and calcium lignosulfonate

A2 WETTABLE POWDER

20 percent by weight active ingredient

35 percent by weight fuller's earth

8 percent by weight calcium lignosulfonate 2 percent by weight sodium salt of

N-methyl-N-oleyltaurine

35 percent by weight silicic acid

B PASTE

45 percent by weight active ingredient

5 percent by weight sodium aluminium silicate 15 percent by weight cetylpolyglycol ether with 8 moles ethylene oxide

2 percent by weight spindle oil

10 percent by weight polyethylene glycol

23 parts water

C EMULSIFIABLE CONCENTRATE

20 percent by weight active ingredient

75 percent by weight isophorone

5 percent by weight of a mixture of

ionic and nonionic surfactants The following examples illustrate the preparation of compounds according to the invention.

Preparation Example 1

3,4-bis-(4-chloroohenyl)-N-(4-trifluoromethyl- 1-cyclohexen-1-yl)-4,5-dihydropyrazole-1-carboxamide

1.70 g (7.76 mmol) 4-trifluoromethylcyclohex-1-enecarbonyl azide was dissolved in 20 ml absolute toluene and under inert conditions (nitrogen), heated to 100°C, until no more gas evolution was observed, In this way,

4-trifluoromethyl-cyclohex-1-enyl isocyanate was formed. The mixture was then cooled to 0°C, and 2.26 g (7.76 mmol) 3,4-bis-(4-chloro-phenyl)-4,5-dihydropyrazole added. After stirring for 10 minutes at 0°C, the mixture was allowed to rise to room temperature and stirred for a further hour. It was diluted with ca. 20 ml hexane and the product crystallised out. It was suction filtered and washed with hexane.

Yield: 2.15 g (52% of theory)

colourless crystals

m.p.: 167-169°C

R_f = 0.84 (silica gel/ethyl acetate)

Preparation of the starting materials 4-Trifluoromethylcyclohex-1-enecarbonitrile

12.72 g (76.56 mmol) 4-Trifluoromethylcyclohexanone was added to 50 ml absolute toluene. 0.6 g zinc iodide was added followed by dropwise addition of 11.08 g (111.01 mmol) trimethylsilyl cyanide. At the end of the exothermic reaction, the mixture was stirred for a further 2 hours. 125 ml Pyridine and 35.22 g (229.68 mmol) phosphorus oxychloride was added and the mixture heated for ca. 8 hours at ca. 100 °C. The mixture was cooled to room

temperature and added to ice/hydrochloric acid mixture and extracted with ether. The combined organic phases were washed with 2M hydrochloric acid, saturated aqueous sodium hydrogen carbonate and saturated aqueous sodium chloride, dried over magnesium sulfate and concentrated in a rotary evaporator. The residue was fractionally distilled in vacuo.

Yield: 8 g (60% of theory)

colourless crystals

m.p. : 35-40°C

b.p. : 50°C/0.3 mm

4-Trifluoromethylcyclohex-1-enecarboxylic acid

8.0 g (45.68 mmol) 4-Trifluoromethylcyclohex-1-enecarbonitrile was heated with 50 ml phosphoric acid (85%) for 8 hours on an oil bath at 140°C, with vigorous stirring. The mixture was cooled, 100 ml water added and extracted with ethyl acetate. The organic phase was extracted twice with 100 ml 2M sodium hydroxide. The aqueous phase was washed several times with ethyl acetate. It was then acidified with 5M hydrochloric acid and again extracted with ethyl acetate. The organic phase was dried over magnesium sulfate and concentrated in a rotary evaporator. The residue was treated with cold hexane and concentrated in vacuo .

Yield: 6.0 g (68% of theory)

colourless crystals

m.p.: 192-194°C

R_f = 0.57 (silica gel/ethyl acetate) 4-Trifluoromethylcyclohex-1-enecarbonyl azide

4.0 g (20.6 mmol) 4-Trifluoromethylcyclohex-1-enecarboxylic acid and 2.53 g (25.54 mmol) triethylamine was dissolved in 40 ml absolute acetone. At 0°C, a solution of 2.24 g (20.60 mmol) ethyl chloroformate in 20 ml absolute acetone was added dropwise over ca. 30 mins. The mixture was stirred for ca. 1 h and the precipitated hvdrochloride suction filtered. The acetone was removed using a rotary evaporator. The residue treated at a temperature below

15°C with a solution of 1.69 g (26.03 mmol) sodium azide in 20 ml water/acetone (1:1). The mixture was stirred vigorously for ca. 1 hour, extracted with ether, and the extract dried over potassium carbonate and a molecular sieve and concentrated in vacuo at room temperature. The crude product was then used without further purification.

In a similar manner, the following compounds of formula in which R³, R⁵ and R⁸ are hydrogen were prepared:

The following examples illustrate the possibilities for use of the compounds of the invention.

Test Example A

Activity against adult cotton boll-weevil (Antkonomus grandis)

The compounds of the invention were made up as aqueous preparations at a concentration of 0.1%. 0.2 ml of this preparation was pipetted onto feed material, in a

polystyrene petri dish and 0.2 ml onto the bottom of the petri dish. After drying, 5 adult (2 day old) cotton boll-weevils (Anthonomus grandis) were counted into the dishes. The closed dishes were left for up to 7 days at 25°C under extended daylight conditions. The % mortality of the weevils at the end of the test indicated the level of activity.

The compounds of Examples 1-10 showed 80 - 100% activity.

Test Example B

Activity against larvae (L1) of the cotton bollworm

(Heliothis virescens) The compounds of the invention were tested in a similar manner to Test Example A using 10 L1 of the cotton

bollworm (Heliothis virescens ) on the feed material.

The compounds of Examples 1-10 showed 80 - 100% activity .

Claims

1. Substituted pyrazoline derivatives of general formula I

in which

R¹, R² and R⁴, which may be the same or different, are

or R¹ and R² together form an optionally benzo fused

alkylene group,

R⁶, R⁷ and R⁸, which may be the same or different are

R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form, an optionally substituted cycloalkenyl ring.

2. Pyrazolines according to claim 1, in which

R¹, R² and R⁴, which may be the same or different, are

hydrogen, or are phenyl, optionally substituted by one or more of the same or different , halogen , nitro , cyano , C_1-6-alkyl , C_1-6-alkoxy ,

C_1-6-alkoxycarbonyl , C_1-6-alkylthio , halo-C_1-6-alkyl , halo-C_1-6-alkoxy , halo-C_1-6-alkoxycarbonyl , halo- C_1-6-alkylthio , C_1-6-alkylsulfonyl or

halo-C_1-6-alkylsulfonyl , or are C_5-8-cycloalkyl or C_5-8-cycloalkenyl , each of which is optionally

substituted by one or more of the same or dif ferent , cyano , C_1-6-alkyl , halo-C_1-6-alkyl , C_1-6-alkoxy, halo- C_1-6-alkoxy , C_1-6-alkylthio , halo-C_1-6-alkylthio ,

C_1-6-alkoxycarbonyl or halo-C_1-6-alkoxycarbonyl, or are C_1-6-alkyl, C_1-6-alkoxycarbonyl, C_1-6-alkylcarbonyl or C_1-6-alkenyl, each of which is optionally substituted by halogen, nitro or cyano,

R⁶, R⁷ and R⁸, which may be the same or different are

C_5-8-cycloalkenyl, each of which is optionally

C_1-6-alkoxycarbonyl or halo-C_1-6-alkoxycarbonyl, or are C_1-6-alkyl, C_1-6-alkoxycarbonyl, C_1-6-alkylcarbonyl or C_1-6-alkenyl, each of which is optionally substituted by halogen, nitro or cyano, or

R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form a C_5-8-cycloalkenyl ring, optionally substituted by one or more of the same or different, halogen, cyano, C_1-6-alkyl, C_1-6-alkoxy, C_1-6-alkylthio, C_1-6-alkoxycarbonyl, halo-C_1-6-alkyl, halo-C_1-6-alkoxy, halo-C_1-6-alkylthio or halo-C_1-6-alkoxycarbonyl,

C_1-6-alkylsulfonyl.

3. Pyrazolines according to claim 1 or 2, in which aatt lleeaast one of R¹, R² and R⁴, is optionally substituted phenyl

4. Pyrazolines according to claim 3, in which

both R¹ and R² are optionally substituted phenyl.

5. Pyrazolines according to any one of the preceding claims, in which R⁴ is hydrogen.

6. Pyrazolines according to claim 4, in which

R¹ and R² are phenyl optionally substituted by halogen, cyano or halo-C_1-6-alkoxy.

7. Pyrazolines according to any one of the preceding claims, in which R⁸ is hydrogen and either R⁶ is hydrogen, in which case R⁷ is optionally substituted phenyl, in which the substituents are halogen, nitro, cyano, C_1-6-alkyl, C_1-6-alkoxy, halo-C_1-6-alkyl or halo-C_1-6-alkoxy, or R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form an optionally substituted C_5-8-cycloalkenyl ring, preferably a cyclohexenyl ring, in which the substituents are preferably halogen, cyano, C_1-6-alkyl, C_1-6-alkoxy, halo-C_1-6-alkyl or halo-C_1-6-alkoxy, and especially C_1-6-alkyl, or halo-C_1-6-alkyl.

8. Pyrazolines according to any one of the preceding claims, in which R³, R⁴ and R⁵ are all hydrogen,

9. Pyrazolines according to any one of the preceding claims, in which

R¹ is 4-cyanophenyl, 4-fluorophenyl, 4-chlorophenyl,

4-isopropoxyphenyl, 4-butoxyphenyl or

4-(2,2,2-trifluoroethoxy)phenyl,

R² is 4-cyanophenyl, 4-fluorophenyl- or

4-chlorophenyl or 4-isopropoxyphenyl,

R³, R⁴, R⁵ and R⁸ are hydrogen, and either

a) R⁶ is hydrogen and R⁷ is 4-trifluoromethylphenyl,

3-trifluoromethylphenyl, 4-nitrophenyl- 4-trifluoromethoxyphenyl, 3-trifluoromethoxyphenyl, 4-(1,1,2,2-tetrafluoroethoxy)phenyl, or

4-fluoro-3-trifluoromethylphenyl, or

b) R⁶ and R⁷ together with the C-C double bond attached to the nitrogen form cyclohex-1-enyl, 4-methylcyclohex- 1-enyl or 4-trifluoromethylcyclohex-1-enyl.

R¹ is 4-cyanophenyl, 4-fluorophenyl or

4-(2,2,2-trifluoroethoxy),

R² is phenyl, 4-cyanophenyl, 4-fluorophenyl- or

4-difluoromethoxy,

R³ is 4-difluoromethoxyphenyl, 4-trifluoromethylphenyl-, 4-trifluoromethoxyphenyl-,

4-(2,2,2-trifluoroethoxy)phenyl-, 4-chlorophenyl-, 4-cyanophenyl- or 4-trifluoromethylcyclohexyl, and

R⁴ is hydrogen or methyl.

10. An insecticidal and acaricidal composition which comprises a compound claimed in any one of claims 1 to 9 in admixture with an agriculturally acceptable diluent or carrier.

11. Use of a compound claimed in any one of claims 1 to 9, for combating insects or acarids.

12. A method of combating insects and acarids which comprises applying to the insect or acarid or their locus, an effective amount of a compound claimed in any one of claims 1 to 9.