CS254526B1 - Insecticide agent - Google Patents

Abstract

Insecticidal composition based on a mixture of isomers of alpha-cyano-3-phenoxybenzyl ester of 2,2-dimethyl-3-(2,2-dichlorovinyl)-cyclopropanecarboxylic acid of formula I consists in containing stereoisomers of absolute configuration lR, 3R, alpha-S, IR, 3R, alpha-R, 1S, 3S, alpha-S, 1S, 3S, alpha-R in the range of weight ratios 1:1:1:1 to 4:1:1:4.

Description

The invention relates to a novel insecticidal composition.

It is known that some cyclopropanoic acid esters exhibit significant insecticidal activity. The possibility of using 2,2-dimethyl-3- (2,2-dichlorvinyl) cyclopropanecarboxylic acid esters as an insecticidal agent was proposed for the first time by MS. (J. Farkas, F. Sorm: Collection Czech. Chem. Commun. 22, 2230, 1959). Their work initiated further extensive research, which resulted in the synthesis of 2,2-dimethyl-3- (2,2-dichlorvinyl) cyclopropanecarboxylic acid alpha-cyano-3-phenoxybenzyl ester of the formula I with extraordinary insecticidal activity (K. Naumann: Chemie der Synthetic Pyrethroid Insectizide, page 10, Springer Verlag, Berlin, 1981).

This substance, also known under the technical name Cypermethrin, contains three asymmetric carbons in the molecule, indicated by the Arabic numerals 1 and 3 on the cyclopropane ring in Formula I and the Greek alpha on benzyl carbon, allowing for a total of eight separate stereoisomers differing in absolute configuration and optionally also the geometric arrangement of the substituents (cis or trans) on the cyclopropane ring. The following designations are used to describe these stereoisomers:

Isomer configuration

AND IR, 3R, alpha-S (B) IR, 3R, alpha-R C IR, 3S, alpha-S D IR, 3S, alpha-R E 1S, 3S, alpha-S F 1S, 3S, alpha-R G 1S, 3R, alpha-S H 1S, 3R, alpha-R

The insecticidal activity of the individual isomers of the compound of formula I is still only partially known. However, some bioassay results show (eg P. Ackermann, F. Bourgeouis, J. Drabek: Pestic. Sci. 11, 169 (1980)) that there may be differences of several orders between individual stereoisomers. The efficiency found decreases in the order of the stereoisomers A C B D E, F, G, H.

While this sequence provides some guidance for the formulation of an optimal insecticidal composition based on a compound of Formula I, other important factors need to be taken into account at the same time, especially

(a) existing possibilities for the stereoselective synthesis of the most potent isomers, respectively. their.mixes,

(b) the economic aspects of such stereoselective synthesis;

c) the possibility of synergistic or antagonistic interaction of the different isomers present in the mixture.

The importance of these factors will in part be apparent from the following review of the state of the art:

Most of the syntheses of the compound of formula I so far described are non-stereoselective or the formation of less active isomers is predominant (see, e.g., K. Naumann: Chemie der synthetischen Pyrethroid-Insectizide, p. 23 et seq., Springer Verlag, Berlin, 1981). Therefore, the production of a mixture of all eight stereoisomers of formula (I) in which the individual isomers are approximately in a statistical ratio prevails in the world. Recently, methods have been found for the stereoselective and economical preparation of a mixture consisting of an enantiomeric pair of A and F isomers in a ratio of 1: 1 and their production has begun on a technical scale. However, the results of the insecticidal activity tests of the mixture of isomers A and F are unsatisfactory, since at least two cases have found a significant effect of the antagonist factor between the two isomers, reducing the insecticidal activity of the composition (M. Elliott, AWFarnham, NJ Jones, DM Doderlund: Sci., 9, 112, (1978).

The resulting action of synergistic and antagonistic factors in the mixture of isomeric insecticides cannot be predicted based on the knowledge of the present art. The results of some tests show that antagonist factors do not appear to be significantly present in the mixture of eight isomers of the compound of Formula I, and in some situations, synergistic factors may be predominant (see, e.g., I.A. Black et al., Proc.

BCPC, Srighton Conf. 1979, p. 377).

An antagonistic effect similar to that found in the mixture of A and F isomers has also been demonstrated for deltamethrin isomers (M. Elliott et al., Pěstíc, Sci. 9, 112, 1978). Similar facts have been shown for resmethrin and allethrin (J.C. Wickham: Fist. Sci. 7, 273, 1976). In contrast, synergistic factor has been found for mixtures of optical isomers of other pyrethroids (M. Ohno et al., Pestic. Sci. 7, 241, 1976). Therefore, the insecticidal activity of a mixture of stereoisomers cannot simply be assessed on the basis of the activity of the individual isomers contained, but the mixture must always be regarded as an integral whole.

The above-mentioned disadvantages are overcome by the insecticidal composition according to the invention, characterized in that it contains as active ingredient a mixture of four stereoisomers A, Β, E, F, i.e. stereoisomers of the absolute configuration IR, 3R, alpha-S, IR, 3R, alpha-R , 1S, 3S, alpha-S and 1S, 3S, alpha-R of the formula I, in ratios of 1: 1: 1: 1 to 4: 1: 1: 4.

An unexpectedly high insecticidal activity is a novel and useful aspect of the composition of the invention. Surprisingly, the insecticidal activity of the composition according to the invention is not only superior to that of a known isomeric mixture of compounds of formula I consisting of all eight stereoisomers of AH in roughly statistical ratios, but is also higher than that of a commercial formulation containing enantiomeric pair A and F in a ratio of 1: 1, although the content of the isomers A, which in itself is the most insecticidally effective, is lower in the composition according to the invention.

The insecticidal composition of the invention may be used in any formulation known per se from the application of natural or synthetic pyrethroid insecticides. In addition to the active ingredient, the composition may contain a carrier, a non-ionic surfactant, and conventional synergistic compounds. The composition can be applied in a variety of ways, for example, as a dust, granulate, suspension, emulsion, solution, aerosol, etc. Depending on the method of application, either a liquid carrier such as water, alcohols, hydrocarbons or other organic solvents, mineral plant or animal oils or a solid carrier such as talc, clay, silica gel, perlite and the like can be selected.

Said compositions preferably contain from 0.005 to 20% by weight of active ingredient. The compositions can be advantageously used for controlling insects in particular in agriculture, fruit growing, forestry, veterinary applications and in households.

Some insecticidal activity assays are described in the examples.

Example 1

Activity on individual organisms was monitored for three isomeric mixtures or isomers of the ester of formula I. The composition of each mixture was designated as follows:

Substance 1 Mixture of isomers A, Β, E, F - each 25%

Substance 2 Cypermethrin (commercial - 40% cis isomers)

Substance 3 A mixture of isomers A, Směs, E, F in a ratio of 4: 1: 1: 4.

The composition of the active compound according to the invention was determined as follows: Quantification of the individual components was carried out by high performance liquid chromatography. Was a 25x0.5 cm Spherisorb S5CN column used? eluent n-hexane-0.2% tetrahydrofuran. In this way, the pair of isomers A, F is totally separated from the pair of isomers Β, E. The individual pairs of isomers do not exhibit optical rotation and are therefore racemates? hence, the ratio of A: F and B: E isomers in the mixture is 1: 1.

The determination of the ratio of the isomeric pairs A, F and poměru, E was performed using an internal standard (1,3-dichloro-4,6-dinitrobenzene) with an accuracy of ± 4%. Typical retention times for said isomeric pairs are 16 and 14 min. at a flow rate of 2 ml / min. This methodology found that the ratio of isomers in compound 3 was 4: 1: 1: 4 (A: B: E: F) and in compound 1 was 1: 1: 1: 1. Chemical identification of the separated racemic pairs of isomers was performed spectrally (NMR, IR) by comparison with automated samples obtained by known literature procedures.

(a) Effectiveness study on housefly

The tested insects are flies of mixed sex. Administration of the active ingredient is performed by topical application of 1 µl of acetone solution to the dorsal thorax of the test insect. 50 insect individuals are used and mortality is determined 24 hours after application. 5 determinations are made and the lethal dose is calculated ^ld 5q. Doses are given in pg per subject.

Substance 1 2 3 Batch 2 0 98% 62 100% 10 62 34% 88% 2.5 22% 12% 32% ^LD 50 7.3 16.8 4.1

(b) Study of efficacy on Spodoptera Littoralis larvae

The assays were again performed by topical application of 1 µl of a solution of the active ingredient in acetone to each individual's thorax. 30 caterpillars of stage 4 larvae were used and LD50 was counted from 5 consecutive 24-hour mortality determinations.

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Dose 5 91 % 76 % 100 ALIGN! % 2.5 76 % 46 % 91 % 1.5 54 % 28 % 77 % 0.5 26 % 11 % 40 % ^LD 50 1, , 3 2, .8 0, , 6

c) Study of insecticidal activity on Phaedon cochlearie

The determination was performed according to the described methodology (M. Elliot and and the relative molar potencies thus obtained are:

spol., Pestic. Sci. 9, 112 (1978))

3

100,500 1,400

Example 2

Greenhouse experiment

The active substances were labeled as follows:

Substance 1 1: 1: 1: 1 mixture of A, Β, E, F isomers Substance 2 1: 1 mixture of A, F isomers

The substances were applied by spraying on a cucumber culture infected with greenhouse aphids. The insect mortality is shown in the table.

concentration of the composition substance 1 substance 2 0.000 1 72.0 66.9 0,000 3 86.7 84.7 0.001 94.0 94.7 0.003 99.8 99.4

Claims (1)

SUBJECT OF THE INVENTION Insecticidal composition based on a mixture of 2,2-dimethyl-3- (2,2-dichlorvinyl) cyclopropanecarboxylic acid alpha-cyano-3-phenoxybenzyl ester isomers of the formula I, characterized in that it contains stereoisomers of the absolute configuration IR, 3R, alpha- S, IR, 3R, alpha-R, 1S, 3S, alpha-S, 1S, 3S, alpha-R in the weight ratios of 1: 1: 1: 1 to 4: 1: 1: 4.