DD251981A5 - PROCESS FOR THE PREPARATION OF 4,5-DIHYDRO-1,3,4-THIODIAZOLE DERIVATIVES - Google Patents

Abstract

The invention relates to a process for the preparation of novel optionally substituted 2-phenyl-5-pyridyl-4,5-dihydro-1,3,4-thiadiazoles of the formula in which R 1 is hydrogen or C 1 -C 4 -alkyl; R is hydrogen, C 1 -C 4 -alkyl, halogen, nitro, cyano, C 1 -C 4 -alkoxy, C 1 -C 4 -alkylthio, C 1 -C 4 -haloalkyl having 1 to 9 halogen atoms, C 1 -C 4 -haloalkoxy having 1 to 9 halogen atoms, C 1 C4-haloalkylthio having 1 to 9 halogen atoms, phenyl, substituted phenyl, phenylalkyl, substituted phenylalkyl, phenoxy, substituted phenoxy, phenylthio, substituted phenylthio, pyridyloxy or substituted pyridyloxy, and n is a number from 1 to 5; and their salts and optical isomers. The new compounds have, in particular, good activity against plant-inducing sucking insects. formula

Description

will be produced.

Field of application of the invention

The present invention relates to a process for the preparation of novel, optionally substituted 2-phenyl-5-pyridyl-4,5-dihydro-1,3,4-thiadiazoles and their use in pest control.

Characteristic of the known technical solutions

The claimed compounds of the formula I are novel. There is no prior art which is close to the structural type proposed according to the application.

From the general literature processes for the preparation of 4,5-dihydro-1,3,4-thiadiazoles are known, for. & Evans, et al., J. Chem. Soc. Chem. commun, 1982, 1888; K.N. Zelenin et al., Khim. Geterotsikl. Soedin, 1982 No. 7, 904.

Object of the invention

The aim of the invention is the provision of new compounds with a strong pesticidal, in particular acaricidal action.

Explanation of the essence of the invention

The invention has for its object to provide novel compounds with the desired properties and methods for their

To find production.

According to the invention, new 2-phenyl-5-pyridyl-4,5-dihydro-1,3,4-thiazole derivatives of the formula I

(D

manufactured,

wherein

R ₁ is hydrogen or C _r C ₄ alkyl;

R is hydrogen, C ₁ -C ₄ -alkyl, halogen, nitro, cyano, C _r C ₄ alkoxy, Ci-C ₄ alkylthio, C _r C ₄ -haloalkyl having 1 to 9 halogen atoms, Crd-haloalkoxy having 1 to 9 halogen atoms , CiC ^ haloalkylthio having 1 to 9 halogen atoms, phenyl, substituted phenyl, phenylalkyl, substituted phenylalkyl, phenoxy, substituted phenoxy, phenylthio, substituted phenylthio, pyridyloxy ost substituted pyridyloxy and

η is a number from 1 to 5; and the salts and optical isomers of a compound of the formula I.

According to the invention, preference is given to compounds of the formula I in which

R _{1 is} hydrogen or C ₁ -C ₄ -alkyl;

R is hydrogen, C ₁ -C ₄ -alkyl, halogen, nitro, cyano, C ₁ -C ₄ -alkoxy, C _r C ₄ alkylthio, -C ₄ -haloalkyl having 1 to 9 halogen atoms,

dC ₄ -haloalkoxy having 1 to 9 halogen atoms or dQ-Halogenalkylthio having 1 to 9 halogen atoms and η is a number from 1 to 5.

Further preferred according to the invention are compounds of the formula I in which η is 1 or 2.

If R in the compounds of the formula I has the meaning of substituted phenyl, substituted phenylalkyl, substituted phenoxy, substituted phenylthio or substituted pyridyloxy, where these radicals may be substituted 1 to 3 times, preferably 1 times, as substituents independently of one another preferably the following Consider: C ₁ -C ₄ -alkyl, halogen, preferably fluorine or chlorine, nitro, cyano, C ₁ -C ₄ -alkoxy, C ₁ -C ₄ -alkylthio, C-pC / i-haloalkyl having 1 to 9 halogen atoms , C 1 -C ₄ -haloalkoxy having 1 to 9 halogen atoms and cyd-haloalkylthio having 1 to 9 halogen atoms. Of particular interest are those compounds of the formula Ia) ₍

worjn,

R ₁ is hydrogen or -C ₄ alkyl, trifluoromethyl, C ₁ -C ₄ -alkoxy or nitro

mean; and the salts of a compound of the formula Ia), and in particular those compounds of the formula Ia) in which R _{1 is} hydrogen, methyl or ethyl;

R ₂ and R _{3 are} independently hydrogen or in the 2- and / or 4-position halogen.

In addition, preference is given to those compounds of the formulas I or Ia) according to the invention in which R ₁ and / or R _{3 are} hydrogen.

Because of their biological activity, those compounds of the formula I or Ia are of particular interest, wherein the

Pyridyl is bound with its 3-position to the 5-position of the 4,5-dihydro-1,3,4-thiadiazole ring. :

The present subject matter of the invention also encompasses the salts, in particular the plant-physiologically acceptable salts, of the compounds of the formulas I or Ia). As such salts with organic and inorganic acids are e.g. the following: chlorides, bromides, iodides, sulfates, hydrogen sulfates, chlorates, perchlorates, rhodanides, nitrates, phosphates, hydrogen phosphates, tetrafluoroborates, formates, acetates, T.richloracetate, trifluoroacetates, phenylsulfonates, oxalates malonates, succinates, malates, tartrates or Citrate.

The subject of the invention further comprises the optical isomers of the compounds of the formulas I and Ia, respectively, which can be obtained from the racemic forms in a manner known per se by means of the customary separation methods.

The compounds of the formula I or la) can be prepared in a manner known per se (compare D.M. Evans et al., J. Chem. Soc., Chem.

1982.188; K.N. Zeletin et al., Khim. Geterotsikl. Soedin, 1982 No. 7, 904) are prepared by reacting a compound of formula II

V ",

with a compound of the formula III ₍

S "" s / ⁿ

-NH-C ^ y

H ₂ N-NH-C ^ y . (III).

wherein in the compounds II and III R ₁ , R and η have the meanings given above under formula I (method a). The compounds of formula I or la) can also be prepared in a novel manner by reacting a compound of formula IV _f

i 91 / · ⁼ · ν ^ ^η

wherein R ₁ , R ₂ and η have the meanings given above under formula I, with a sulfide (process b). If appropriate, it is possible to convert a compound of the formulas I or la) obtained as indicated above into one of its salts in a manner known per se.

The process a) according to the invention of the formulas I or I a) is preferably carried out in a solvent. Suitable solvents are, for. Aromatic hydrocarbons such as benzene, toluene and xylene; Ketones such as acetone, cyclohexanone and methyl ethyl ketone; Ethers, such as tetrahydrofuran, dioxane and diethyl ether; halogenated hydrocarbons, such as chloroform, carbon tetrachloride and chlorobenzene; Alcohols, such as ethanol and propanol; Esters of aliphatic acids, such as ethyl acetate; aliphatic amides such as dimethylformamide and dimethylacetamide; Dimethyl sulfoxide and other solvents that do not interfere with the reaction. These solvents can also be used as mixtures. The reaction temperature can be in a wide range of -10 to + 200 ° C. A temperature range of room temperature is preferably up to about 15O ⁰ C.

Process b) is preferably carried out in a polar solvent such as water, an alcohol, e.g. As methanol or ethanol performed. The ring closure reaction is carried out with a sulfide, preferably a soluble metal sulfide, such as sodium or potassium sulfide, or a corresponding hydrogen sulfide, with an alkaline medium being preferred. The reaction temperature may be in the range of -15 to + 100 ⁰ C. A temperature range of -10 to + 5O ⁰ C, ZBRaumtemperatur is preferred.

The pyridine-carbonyl compounds of the formula II used as starting materials and thiobenzoic acid of the formula III are known and can be obtained analogously to known methods. The substituted 2,3-diazabutadienes of the formula IV, which likewise form an object of the present invention as novel compounds, are analogously to known procedures (compare WT Flowers et al., J. Chem. Soc., Perkin, Trans., 1 (2) , 349, 1981) as follows, where R ₁ , R and η are as defined above:

I II + H ₂ N-NH-C- _{Ν /} ~ I II 'IV

V * Λ-; ' V.

(SOCl ₂ )

It has been found that the compounds of the formulas I or la) according to the invention have excellent activity as pesticides with good plant tolerance and low toxicity to warm-blooded animals. They are especially suitable for controlling plant and animal infesting pests.

In particular, the compounds of the formulas I or la) are suitable for controlling insects of the orders Lepidoptera, Coleoptera, Homoptera, Heteroptera, Diptera, Thysanoptera, Orthoptera, Anoplura, Siphonaptera, Mallophaga, Thysanura, Isoptera, Psocoptera and Hymenoptera, and of representatives of the order Acarina.

The good pesticidal activity of the compounds according to the invention corresponds to a mortality of at least 50-60% of the pests mentioned.

With the aid of the compounds of the formula I or Ia according to the invention it is possible above all to combat plant-damaging insects, especially plant-damaging insects in ornamental and useful plantings, in particular in cotton crops, vegetable crops, rice crops and fruit crops. In this context, it should be emphasized that the compounds mentioned are characterized both by a pronounced systematic, but especially by contact with sucking insects,. especially against insects of the family Aphididae (such as Aphis fabae, Aphis craccivora and Myzus persicae), which are difficult to combat by conventional means, distinguished.

The compounds of the formulas I or la) are furthermore distinguished by a good action against larval insect stages and nymphs, especially of eating noxious insects. In particular, the compounds of the formula I can be used with excellent success against plant-damaging cicadas, especially in rice cultures. The compounds are also useful for controlling ectoparasites, e.g. B. Lucilia sericata, as well as ticks on domestic and farm animals, z. B. by animal, stable and grazing treatment.

The effect of the compounds according to the invention or the compositions containing them can be substantially broadened by the addition of other insecticides and / or acaricides and adapted to given circumstances. As additives z. As representatives of the following classes of active substances into consideration: organic phosphorus compounds, nitrophenols and derivatives, formamidines, ureas, carbamates, pyrethroids, chlorinated hydrocarbons and Bacillus thuringiensis preparations. The compounds of the formulas I and Ia are used in unchanged form or preferably together with the usual in formulation technology aids and are therefore z. B. to emulsion concentrates, directly sprayable or dilutable solutions, dilute emulsions, wettable powders, soluble powders, dusts, granules, and encapsulations in z. B. polymeric substances processed in a known manner. The application methods, such as spraying, misting, dusting, scattering or pouring, as well as the means are chosen according to the desired goals and the given circumstances.

The formulation, ie the agent, or combinations of these agents with other insecticides or acaricides, and optionally a solid or liquid additive containing agents, preparations or compositions are prepared in a known manner, for. B. by intimately mixing and / or grinding the active compounds with extenders, such as with solvents, solid carriers, and optionally surface-active compounds (surfactants). Suitable solvents are: Aromatic hydrocarbons, preferably the fractions C ₃ to C ₁₂ , such as. As xylene mixtures or substituted naphthalenes, phthalic acid esters such as dibutyl or Dioctylphthalat, aliphatic hydrocarbons such as cyclohexane, paraffins, alcohols and glycols and their ethers and esters such as ethanol, ethylene glycol, Äthylenglykolmonomethyl- or -äthyläther, ketones such as cyclohexanone, strongly polar Solvents, such as N-methyl-2-pyrrolidone, dimethyl sulfoxide or dimethylformamide, and optionally epoxidized vegetable oils, such as epoxidized coconut oil or soybean oil, or water.

As solid carriers, for. As for dusts and dispersible powders, natural minerals are generally used, such as calcite, talc, kaolin, montmorillonite or attapulgite. To improve the physical properties, it is also possible to add highly disperse silicas or highly dispersed absorbent polymers. As a granular, adsorptive

Granule carriers come porous types, such as. As pumice, broken brick, sepiolite or bentonite, as non-sorptive carrier materials such. As calcite or sand in question. In addition, a variety of granular materials of inorganic or organic nature, such as in particular dolomite or crushed plant residues can be used.

Suitable surface-active compounds, depending on the nature of the active compound of formulas I or la) to be formulated or combinations of these active ingredients with other insecticides or acaricides, are nonionic, cationic and / or anionic surfactants having good emulsifying, dispersing and wetting properties. Surfactants are also surfactant mixtures.

Suitable anionic surfactants may be both so-called water-soluble soaps and water-soluble synthetic surface-active compounds.

As soaps are the alkali, alkaline earth or optionally substituted ammonium salts of higher fatty acids (CiO-C ₂₂ ), such as. As the Na or K salts of oleic or stearic acid, or of natural fatty acid mixtures, the. Β. can be obtained from coconut or tall oil. Also to be mentioned as surfactants, the fatty acid methyl-taurine salts and modified and unmodified phospholipids.

More often, however, so-called synthetic surfactants are used, especially fatty sulfonates, fatty sulfates, sulfonated benzimidazole derivatives or alkylarylsulfonates.

The fatty sulfonates or sulfates are typically present as alkali, alkaline earth or optionally substituted ammonium salts and generally have an alkyl radical of 8 to 22 carbon atoms, alkyl also including the alkyl moiety of acyl radicals, e.g. the Na or Ca salt of lignosulfonic acid, of dodecylsulphuric acid ester or of a fatty alcohol mixture prepared from natural fatty acids. This subheading also covers the salts of sulfuric acid esters and sulfonic acids of fatty alcohol / ethylene oxide adducts. The sulfonated benzimidazole derivatives preferably contain 2 sulfonic acid groups and a fatty acid residue having about 8-22 C atoms. Alkylarylsulfonates are z. As the sodium, calcium or triethanolamine salts of dodecylbenzenesulfonic acid, dibutylnaphthalenesulfonic acid or a naphthalenesulfonic acid-formaldehyde condensation product. Furthermore, corresponding phosphates, e.g. Salts of the phosphoric acid ester of a p-nonylphenol (4-14) -Äthylenoxid adduct, in question.

Suitable nonionic surfactants are primarily polyglycol ether derivatives of aliphatic or cycloaliphatic alcohols, saturated or unsaturated fatty acids and alkylphenols which may contain 3 to 30 glycol ether groups and 8 to 20 carbon atoms in the (aliphatic) hydrocarbon radical and 6 to 18 carbon atoms in the alkyl radical of the alkylphenols. Further suitable nonionic surfactants are the water-soluble 20 to 250 ethylene glycol ether groups and 10 to 100 propylene glycol ether groups containing Polyäthylenoxidaddukte of polypropylene glycol, Äthylendiaminopolypropylenglykol and alkylpolypropylene glycol having 1 to 10 carbon atoms in the alkyl chain. The compounds mentioned usually contain 1 to 5 ethylene glycol units per propylene glycol unit.

Examples of nonionic surfactants include nonylphenol polyethoxyethanols, castor oil polyglycol ethers, polypropylene-polyethylenebylene oxide adducts, tributylphenoxypolyethoxyethanol, polyethylene glycol, and octylphenoxypolyethanol.

Also suitable are fatty acid esters of polyoxyethylene sorbitols, such as the polyoxyethylene sorbitan trioleate.

The cationic surfactants are, above all, quaternary ammonium salts which contain at least one alkyl radical having 8 to 22 carbon atoms as N-substituent and lower, optionally halogenated, alkyl, benzyl or lower hydroxyalkyl radicals as further substituents. These salts are preferably in the form of halides, methylsulfates or ethylsulfates, e.g. As the stearyltrimethylammonium chloride or the benzyl-di- (2-chloroethyl) ethylammoniumbrornid.

The surfactants commonly used in the formulation technique are i.a. described in the following publications:

"McCutcheon's Detergents and Emulsifiers Annual" MC Publishing Corp., Ridgewood, New Jersey, 1979; Dr. Helmut Stäche "Tensid Taschenbuch", Carl Hanser Verlag Munich / Vienna 1981.

The pesticidal preparations contain - by weight - usually 0.1 to 99%, in particular 0.1 to 95%, of an active compound of the formula I or combinations thereof with other insecticides or acaricides, 1 to 99.9% of a solid or liquid additive and 0 to 25%, in particular 0.1 to 20%, of a surfactant. While more preference is given to concentrated products as a commercial product, the end user generally uses dilute preparations which have significantly lower active substance concentrations.

The compositions may also contain other additives such as stabilizers, defoamers, viscosity regulators, binders, adhesives and fertilizers or other active ingredients to achieve special effects.

embodiment

The invention is explained in more detail below with reference to some examples.

Example 1: Preparation of 2- (4-chlorophenyl) -5- (pyrid-3-yl) -4,5-dihydro-1,3 _/ 4-thiadiazole

39.2 g of p-chlorothiobenzoic acid hydrazide are dissolved in 350 ml of ethanol. 21.4 g of pyridine-3-aldehyde (dissolved in 20 ml of ethanol) are added dropwise to this solution under nitrogen. The reaction temperature is maintained at 20 ° C. by cooling. After completion of the addition, stirring is continued for 1 hour at reflux temperature and then the reaction mixture is filtered through finely divided diatomaceous earth. The filtrate is concentrated to three quarters of its initial volume and the precipitated product is filtered off, washed with hexane and dried. The title compound of the formula is obtained

/ nIV V · '

• ·

with a mp of 106-108 ° C (Compound No. 1.1).

Example 2: Preparation of 2- (3-nitrophenyl) -5- (pyrid-3-yl) -4,5-dihydro-1,3,5-thiadiazole

A solution of 8.7 g of potassium hydroxide in 100 ml of ethanol is saturated with hydrogen sulfide. This solution will be 8.7g

Potassium hydroxide added dropwise in 100 ml of ethanol. Subsequently, the resulting solution with 22.4 g of 1-chloro-1- (3-nitrophenyl) -4- (3-pyridyl) -2,3-diazabutadiene added portionwise with ice cooling. The reaction mixture is stirred for 1 hour at room temperature, then concentrated and the residue taken up in ethyl acetate. The ethyl acetate solution is washed twice with water and twice with saturated brine, dried over sodium sulfate, filtered and evaporated.

Obtained in this way the title compound of the formula

H-

ψ- if

I II

t ·

ho

with a melting point of 109-111 ° C (compound no. 1.2).

In accordance with the procedures described above, the following compounds of formula Ia) are prepared.

connection position Ri Ri R ₂ R ₃ physikal. No. pyridyl dates 1.3 2 H 4-CI H Smp.91-93 ° C 1.4 4 H 4-CI H Mp. 145-147 ⁰ C 1.5 3 -CH ₃ 4-CI H , Mp. 119-120 ⁰ C 1.6 3 H H H Mp. 70-73 ⁰ C 1.7 3 -CH ₃ H H ng ⁰ = 1.6450 1.8 4 -CH ₃ 4-CI H Mp 123-125 ° C 1.9 2 -CH ₃ 4-CI H Mp. 92-93 ⁰ C 1.10 3 : H 2-CI H M.p. 125-126 ⁰ C 1.11 3 H 2-F H Mp. 78-8O ⁰ C 1.12 3 H 4-CH ₃ H Mp. 118-119 ⁰ C 1.13 3 H 4-CF ₃ , H Smp.98-100 ° C 1.14 3 H 3-F H Mp. 73-75 ⁰ C 1.15 3 H 4-F H Mp. 103-105 ⁰ C 1.16 3 H 4-Br H Mp 126-128 ⁰ C 1.17 3 H 3-CI H Mp. 86-87 ⁰ C 1.18 3 H 3-CH ₃ H Mp. 80-82 ⁰ C 1.19 3 H 4-OCH ₃ H Mp. 93-94 ⁰ C 1.20 3 H 3-CI 4-CI Mp. 104-108 ⁰ C As described above, too the following connections the formula la) available: Position· R ₂ R ₃ Pyridyl radical

4 2 4 2 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 In addition, as described above, the following compounds corresponding to formula I are obtainable:

nC ₄ H ₉ H H-CH ₃ H H 4-nC ₄ H ₉ -CH ₃ 4-OCH ₃ H -C ₂ H ₅ H -OCH ₃ -nC ₃ H ₇ 2-F H H 2-CI 6-Cl H 2-CI 4-CI. H 2-CI 3-CI H '3-F 5-F H 3-F 4-F H 2-F 4-F H 2-F 3-F H 4-OCF ₃ H H 4-OCF ₂ CHFCF ₃ H H 4-OCHF ₂ H H 4-CN H H 4-O-phenyl H H ' 4-CH ₂ -Phe.nyl H H 4-S-phenyl H H 3-O-phenyl H H 4-O- (3,5-CI ₂ -pyridyl) H H 4-C ₂ H ₅ H H 3-CI 5-CI

As described above, the following salts of a compound of the formula Ia) are also obtainable:

• · -

/ \ Rv

-0-CF ₂ CHFCF ₃

I Il

Cl

C-CF ₂ CHFCF ₃

• «

tf

/ S | V

I Il

-Cl

/ SJV

I Il

Cl

ii

Connection no.

Position pyridyl radical

salt-forming acid

Physical.

dates

T'c]

2.1 3 H 4-CI H oxalic acid Mp. 200-201 2.2 3 H 4-CI H HBr Mp. 232-234 2.3 3 H 4-CI H p-toluenesulfonic acid Mp. 261-262 2.4 3 H 4-CI H benzoic acid Mp. 70-72 2.5 3 H 4-CI H HCI Mp. 192-193 2.6 3 H 4-CI H HBr Mp. 228-229

Example 3: Formulations for active compounds of the formulas I and I a) according to Example 1 and 2 resp. Combinations of these agents with others Insecticides or acaricides (% = wt%):

1. Spray powder a) b) c)

Active substance or drug combination 25% 50% 75%

Na lignosulfonate 5% 5% -

-a ^ 3I 3Ol

1. Spray powder a) b) c)

Na lauryl sulphate 3% - 5%

Na-diisobutylnaphthalenesulfonate - 6% 10%

Octylphenolpolyäthylenglykoläther

(7-8MoIAeO) - 2% -

Highly disperse silica 5% 10% 10%

Kaolin 62% 27% -

The active substance or combination of active ingredients is mixed with the additives and ground well in a suitable mill.

This gives wettable powders which can be diluted with water to give suspensions of any desired concentration.

2. Emulsion Concentrate

Active substance or active substance combination 10%

Octylphenolpolyethylene glycol ether (4-5MoIAeO) 3%

Ca-dodecylbenzenesulfonate 3%

castor oil

(36MoIAeO) 4%

Cyclohexanone · 30%

Xylene mixture 50%

From this concentrate emulsions of any desired concentration can be prepared by dilution with water.

3. Dusts a) b) Active ingredient or active ingredient combination 5% 8% Talc 95% - kaolin - 92% Ready-to-use dusts are obtained by mixing the active ingredient with the carrier and grinding on a suitable mill.

4. extruder granules

Active substance or active substance combination 10%

Na lignosulfonate 2%

Carboxymethylcellulose 1%

Kaolin 87%

The active ingredient is mixed with the additives, ground and moistened with water. This mixture is extruded, granulated and then dried in a stream of air.

5. Serving Granules

Active substance or combination of active ingredients 3%

Polyethylene glycol (MG200) 3%

Kaolin. 94%

The finely ground active ingredient or combination of active ingredients is applied uniformly in a mixer to the kaolin moistened with polyethylene glycol. In this way, dust-free coating granules are obtained.

6. suspension concentrate

Active substance or active ingredient combination 40%

Ethylene glycol '10%

Nonylphenolpolyäthylenglykoläther

(15MoIAeO) 6%

Na lignosulphonate 10%

Carboxymethylcellulose 1%

37% aqueous formaldehyde solution 0.2%

Siukonöl in the form of a 75%

aqueous emulsion 0.8%

Water 32%

The finely ground active ingredient or combination of active ingredients is intimately mixed with the additives. This gives a 'suspension concentrate from which suspensions of any desired concentration can be prepared by dilution with water.

Example 4: Action against Musca domestica

50g freshly prepared CSMA nutrient substrate for maggots are weighed into beakers. From a 1 wt .-% strength acetone solution of the active ingredient in question, a certain amount is pipetted on the nutrient medium contained in the cups, so that there is an active ingredient concentration of 400 ppm. After mixing the substrate, the acetone is allowed to evaporate for at least 20 hours.

Then, for each active ingredient, 25 one-day maggots of Musca domestica are added to the beakers containing the nutrient substrate so treated. After the maggots have pupated, the formed dolls are separated by flushing with water from the substrate and deposited in closed with strainer vessels.

The peruvian flushed out pupae are counted (toxic influence of the drug on the maggot development). Then after 10 days, the number of flies hatched from the pupae is determined.

Compounds of the formula I or la) according to Examples 1 and 2 show good activity in the above test.

Example 5: Action against Lucilia sericata (larvae)

To 9 ml of a culture medium is added at 50 ⁰ CI ml of an aqueous preparation containing 0.5% active substance. Now about 30 fresh hatched Lucilia sercata larvae are added to the culture medium. After 48 and 96 hours, the insecticidal activity is determined by determining the kill rate. Compounds of the formula I or la) according to Examples 1 and 2 show good activity against Lucilia sericata in this test.

Example 6: Action against Aedes aegypti (larvae)

On the surface of 150 ml of water, which is in a container, as much of a 0.1% acetone solution of the active ingredient is pipetted that a concentration of 200 ppm is obtained. After evaporation of the acetone, the container is charged with 30 to 40 2-day Aedes larvae. After 2 and 7 days the mortality is checked. Compounds of the formula I or la) according to Examples 1 and 2 show good activity in the above test.

Example 7: Contact effect on Aphis craccivora

In pots attracted 4-5 day old pea seedlings (Vicia faba) are populated before the start of each experiment with about 200 individuals of the species Aphis craccivora. The treated plants are sprayed 24 hours later with an aqueous preparation containing the test compound to dripping wet directly. Two plants are used per test compound. An evaluation of the mortality rate achieved after another 24 and 72 hours. The experiment is at 21-22 ° C and a rel. Humidity of about 55% performed.

A mortality of 80-100% in this test gives Compound No. 1.1 according to Example 1 at 3 ppm. The same effect at 400 ppm, the compounds no. 1.6.1.11, 2.1, 2.2, 2.3, 2.4 and 2.5.

Example 8: Systematic effect on Aphis craccivora

Rooted bean plants are transplanted into pots containing 600cm of soil. Subsequently, 50 ml of a preparation of the compounds to be tested (obtained from a 25% wettable powder) in a concentration of 800 ppm are poured directly onto the soil in the pots.

After 24 hours, aphids of the species Aphis craccivora are planted on above-ground plant parts and the plants are put over with a plastic cylinder in order to protect the lice from any direct contact or gas action of the test substance. '

The evaluation of the achieved killing takes place 48 and 72 hours after the beginning of the test. Two plants, one in a separate pot, are used per test substance. The experiment is carried out at 25 ° C and about 70% relative humidity.

Compounds of the formula I or la) according to Examples 1 and 2 show good activity in this test.

Example 9: Contact effect on Myzus persicae

About 4 to 5 days old, in water attracted pea seedlings (Vicia faba) are populated before the start of each with about 200 individuals of the species Myzus persicae. The treated plants are sprayed 24 hours later with an aqueous suspension containing up to 200 ppm of the test compound to dripping wet directly. Two plants are used per test substance. An evaluation of the kill rate achieved is 24 and 72 hours after application. The experiment is carried out at 21-22 ⁰ C and about 60% relative humidity.

Compound No. 1 according to Example 1 gives at 200 ppm, Compound No. 2.5 at 3 ppm and Compounds No. 2.1, 2.2, 2.3 and 2.4 give an 80-100% mortality in this test at 50 ppm.

Example 10: Systematic effect on Myzus persicae

Rooted cabbage plants in the 4- to 5-leaf stage are transplanted into pots containing 60ecm of soil. Subsequently, 50 ml of an aqueous formulation of the compound to be tested (obtained from a 25% wettable powder) in each case in a concentration of 800 ppm poured directly onto the soil.

After 24 hours aphids of the species Myzus persicae are placed on the above-ground parts of the plant and the plants are covered with plastic cylinders to protect the aphids from any direct contact or gas action of the test substance.

The evaluation of the achieved% killing takes place 48 hours after the start of the test. Two plants, one in separate pots, are used per test substance. The experiment is carried out at about 25 ⁰ C and 60% relative humidity.

Compounds of the formula I or I a) according to Examples 1 and 2 show good activity in the above test.

Example 11: Leaf Penetration Effect on Aphis craccivora

In about 8cm high plastic cups (diameter about 6cm) is placed a matching small branch of Vicia faba, which is heavily infected with aphids of the species Aphis craccivora. The cup is covered with a plastic lid with a punched hole of 2 cm diameter in the middle. A leaf of a Vicia faba plant is placed on the opening in the lid without separating this leaf from the potted plant. The sheet is then fixed with a second hole lid on the cup over the opening of the first lid. From the bottom, i. Through the opening of the first lid, the aphids in the cup now infect the overhead leaf of the forage plant. On the upper side, an aqueous preparation of the active substance to be tested in a concentration of 400 ppm is applied evenly to the sheet by means of a brush. It is checked whether the applied on one side of the top of the leaf of the fodder plant test substance in sufficient quantity diffuses through the leaf on its underside to kill there suckling aphids.

The experiment is carried out at about 20 ⁰ C and 60% relative humidity. The evaluation for% mortality is 48 hours after drug administration

 Compounds of the formula I or I a) according to Examples 1 and 2 show good activity in the above test.

Example 12: Gnat poison effect on Laodelphax striatellus and Nilaparvata lugens (nymphs);

The test is performed on growing plants. In each case 4 rice plants (thickness of the stalk 8mm) with a height of approx. 20cm are planted in pots (diameter of 8cm).

The plants are sprayed on a turntable with 100 ml of an acetone solution containing 800 ppm of the respective active ingredient. After the spray coating has dried on, each plant is colonized with 20 nymphs of the test animals in the third stage. To prevent the cicadas from escaping, a glass cylinder open on both sides is placed over the populated plants and covered with a gauze lid. The nymphs are kept on the treated plant for 10 days until they reach the next stage of development. The evaluation on% mortality takes place 1.4 and 8 days after the treatment.

Compounds of the formula I or la) according to Examples 1 and 2 show good activity in this test

Example 13: Ovicidal activity on Laodelphax striatellus and Nilaparvata lugens;

The test is performed on growing plants. Each 4 rice plants (thickness of stem 8mm, height about 20cm) are in pots (diameter of 8cm) implanted.

The plants are sprayed on a turntable with 100 ml of an acetone solution containing 400 ppm of the respective active ingredient. After the spray coating has dried on, each plant is colonized by 3 adult females. To prevent the animals from escaping, a glass cylinder is placed over each colonized plant and covered with a gauze lid.

The females remain for 4 days for oviposition on the treated plant and are then removed.

About 8 days after colonization, the young cicadas hatch, and the counting takes place. From the comparison of the number of hatched larvae on the treated plants to the animals hatched on untreated control plants, the percentage mortality is determined.

Compounds of the formula I or la) according to Examples 1 and 2 show good ovicidal activity in the above test.

Claims (11)

Invention claim: A process for the preparation of 4,5-dihydro-1,3,4-thiadiazole derivatives, characterized in that the preparation of a 2-phenyl-5-pyridyl'-4,5-dihydro-1,3,4 thiadiazoles of the formula I _f R (D, wherein R _{1 is} hydrogen or C _r C ₄ alkyl; R is hydrogen, C ₁ -C ₄ -alkyl, halogen, nitro, cyano, C ₁ -C ₄ -alkoxy, C _r C _r alkylthio, C ₁ -C ₄ -haloalkyl having 1 to 9 halogen atoms, C _r C ₄ -haloalkoxy with 1 to 9 halogen atoms, CT-CrHalogenalkylthio with 1 to 9 halogen atoms, phenyl, substituted phenyl, phenylalkyl, substituted phenylalkyl, phenoxy, substituted phenoxy, phenylthio, substituted phenylthio, pyridyloxy or substituted pyridyloxy and η is a number from 1 to 5; and the salts and optical isomers of a compound of formula I '
a) a compound of formula II (ID with a compound of the formula (Ill), or b) a compound of formula IV (IV), with a sulfide, where R ₁ , R and η have the meanings given above, and optionally converting a compound of formula I obtained into one of its salts or separating it into its optical isomers. 2. A process for the preparation of a compound of formula I according to item!, Characterized in that R ₁ is hydrogen or C _r C ₄ alkyl; R is hydrogen, C ₁ -C ₄ -AlRyI, halogen, nitro, cyano, C _r C ₄ alkoxy, C _r C ₄ alkylthio, C ₁ -C ₄ -haloalkyl having 1 to 9 halogen atoms, -C ₄ -haloalkoxy having 1 to 9 halogen atoms or C-pC ^ halogenoalkylthio having 1 to 9 halogen atoms and η is a number from 1 to 5; and their salts and optical isomers. 3. A process for preparing a compound of formula I according to item 1 or 2, characterized in that η is 1 or 2. 4. The method according to item 3, characterized in that a compound of formula la) (La), in which R _{1 is} hydrogen or C ₁ -C ₄ -alkyl; R -C ₂ and R ₃ are independently hydrogen, halogen, Ci-C ₄ alkyl, trifluoromethyl, C _{1 -C 4} alkoxy or nitro; and the salts of a compound of formula I a). 5. The method according to item 4, characterized in that a compound of formula la) is prepared according to item 4, wherein R _{1 is} hydrogen, methyl or ethyl; R ₂ and R _{3 are} independently hydrogen or located in the 2- and / or 4-position Mean halogen. 6. A process for the preparation of a compound of the formula Ia) according to one of the items 4 or 5, characterized in that R _{3 is} hydrogen. 7. A process for the preparation of a compound according to any one of items 1 to 6, characterized in that R _{1 is} hydrogen. 8. A process for preparing a compound according to any one of items 1 to 7, characterized in that in the formulas I and I a) of the pyridyl radical with its 3-position to the 5-position of the 4,5-dihydro-1.3 , 4-thiadiazole ring is bonded. 9. The method according to item 1, characterized in that a compound according to item 6 of the formula will be produced. 10. The method according to item 1, characterized in that a compound according to item 6 of the formula H H M will be produced. 11. The method according to item 1, characterized in that a compound according to item 6 of the formula