IL43712A - N-methyl-o-phenyl-carbamic acid esters their production and insecticidal compositions containing them - Google Patents

Description

43712/2 N*Methyl-0-phenyl-caroamic acid esters, their production and insecticidal compositions containing them BAYER XSNeSSBI It is already known that N-methyl-0-(alkoxymethyl- phenyl)-carbamic acid esters, such as K-methyl-0-(2-methoxy-methylphenyl)- and -0-(2-ethoxyiaethylphenyl)-carbamlc acid esters, display an insecticidal action (compare Israel Patent Specification No. 23516) .

The N-methyl-O-phenyl-carbamic acid esters according to the invention fall within the generic scope of British Patent Specification No. 912,895. However, none of the small group of compounds according to the invention is specifically disclosed in the said British Specification. In accordance with the present invention it has been surprisingly found that the new compounds possess markedly better insecticidal activity than a compound of similar structure known from said British Specification.

The present invention provides N-methyl-O-phenyl- carbamic acid esters of the general formula in which R denotes alkyl with 1-4 carbon atoms and n denotes one or two.

R preferably denotes methyl, ethyl or propyl.

The invention also provides a process for the production of a NHoaethyl-O-phenyl-caxbamic acid ester of the formula (I) in which a phenol derivative of the formula in which R and n have the abovementioned meanings (a) is reacted with methyl isocyanate, optionally in the presence of a catalyst, or (b) is converted into the corresponding chloroformic acid ester with phosgene, and the ester is reacted with methyl- amine, or (c) is reacted with an approximately equivalent amount of phosgene to give the corresponding bis-phenyl-carbonate and the latter is split with methylamine* Surprisingly, the N-methyl-O-phenylcarbamic acid esters according to the invention display a substantially greater insecticidal action than the compounds of analogous structure and type of action known from the state of the art. The products according to the present invention thus represent a genuine enrichment of the art.

If methyl isocyanate and 2-ethylsulphoxylmethylphenol are used as starting materials, the course of the reaction can be represented by the following reaction scheme; The formula (II) provides an unambiguous general definition of the starting compounds to be used.

Methyl isocyanate, to be used as the starting material in process variant (a), is known from the literature and can be prepared according to known processes. The phenol derivatives (II) can be prepared according to processes which alkylmercaptan in the presence of alcoholate - either with hydrogen peroxide in methanol in the presence of catalytic amounts of sulphuric acid to give the sulphoxide compounds or with hydrogen peroxide in glacial acetic acid in the presence of catalytic amounts of sulphuric acid to give the corresponding sulphone compounds.

The following may be mentioned individually as examples of phenol derivatives to be reacted in accordance with the process: 2-methyl-, 2-ethyl-, 2-n-propyl- or 2-iso-propyl-sulphoxide- or -sulphonylmethylphenol.

The process of the invention is preferably carried out in the presence of a solvent (this term includes a mere diluent). As such, it is possible to use practically all inert organic solvents. Particular examples include aliphatic and aromatic, optionally chlorinated, hydrocarbons, such as benzene, toluene, xylene, benzine, methylene chloride chloroform, carbon tetrachloride and chlorobenzene; ethers, such as diethyl ether, dibutyl ether and dioxan; ketones, such as acetone, methyl ethyl ketone, methyl isopropyl ketone and methyl isobutyl ketone; and ni riles, such as aceto-nitrile and propionitrile.

As catalyst in process variant (a) it is possible to use a base, preferably a tertiary base, for example tri-ethylamine, dimethylbenzylamine or pyridine.

The reaction temperature can be varied over a wide range. In general, the reaction is carried out at 0 to 100°C, preferably at 15 to 30°C, and generally under normal pressure.

In carrying out the process according to the invention the starting substances are generally employed in equivalent variant (a) can be used in less than the equivalent amount and the phosgene in process variant (b) is generally used in excess. The first step of process variant (b) is preferably carried out at a Pg below 7, and the first step of process variant (c) preferably at a Pj^of approximately 8.

The reaction mixture may be worked-up in the usual manner by filtration, drying and recrystallisation.

The compounds according to the invention are obtained in a crystalline form and are characterised by their melting point.

As has already been mentioned, the N-methyl-O-phenyl-carbamic acid esters according to the invention are distinguished by outstanding insecticidal activity, especially towards plant pests. They combine low phototoxicity with a good action against both sucking and biting insects.

To the sucking insects there belong, in the main, aphids (Aphidae) such as the green peach aphid (Myzus persicae) , the bean aphid (Doralis fabae), the bird cherry aphid (Rhopalosiphum padi) , the pea aphid (Macrosiphum pisi) and the potato aphid (Macrosiphum solanifolii) , the currant gall aphid (Cryptomyzus korschelti) , the rosy apple aphid (Sappaphis mali), the mealy plum aphid (Hyalopterus arundln1 s) and the cherry black-fly (Myzus cerasi) ; in addition, scales and mealybugs (Ooccina) , for example the oleander scale (Aspidiotus hederae) and the soft scale (Lecanium hesperidum) as well as the grape mealybug (Pseudococcus maritimus) ; thrips (Thysanoptera) , such as Hercinothrips femoralis, and bugs, for example the beet bug (Piesma quadra a) . the red cotton bug (¾ysdercus intermedius), the bed bug (Cimex leotularius) . the assassin bu (Rhodnius prolixus) and Cha as' bu bilobatus and Nephotettix bipunctatus.

In the case of the biting insects, above all there should be mentioned butterfly and moth caterpillars (Lepidoptera) such as the diamond-back moth (Plutella maculipennis) . the gipsy moth (Lvmantria dispar). the brown-tail moth (Euproctis chrysorrhoea) and tent caterpillar (Malacosoma neustria) ; further, the cabbage moth (Mamestra brassicae) and the cutworm (Agrotis segetum) t the large white butterfly (Pieris brassicae) . the small winter moth (Cheimatobia brumata) , the green oak tortrix moth (Tortrix viridana) t the fall armyworm (Laphygma frugiperda) and cotton worm (Prodenia litura) , the ermine moth (Rvponomeuta padella) . the Mediterranean flour moth (Ehestia khril ella) and reater wax moth (Salleria mellonella) .

Also to be classed with the biting insects are beetles (Coleoptera) . for example the ranary weevil (Sitophilus granarius = Calandra granaria). the Colorado beetle (Leptino-tarsa decemlineata) , the dock beetle (Gastrophvsa viridula) , the mustard beetle (Phaedon cochleariae) , the blossom beetle (Meligethes aeneus) , the raspberry beetle (Byturus tomentosus) , the bean weevil (Bruchidius = Acanthoscelides obtectus). the leather beetle (Permeates frischi) t the khapra beetle (Trogo-derma granarium) . the flour beetle (Tribollum castaneum). the northern corn billbug (Calandra or Sitophilus zeamais) . the drugstore beetle (Stegobium paniceum). the yellow mealworm (Tenebrio molitor) and the saw-toothed grain beetle (Or zae-philus surinamensis) , but also species living in the soil, for example wireworms (Agriotes spec.) and larvae of the cockchafer (Melolontha melolontha) : cockroaches, such as the German cockroach (Blattella germanica) . American cockroach Rhvparobia maderae) . oriental cockroach (Blatta orientalis ) . the giant cockroach (Blaberus gjganteus) and the black giant cockroach (Blaberus fuscus) as well as Henschoutedenia flexivitta: further, Orthoptera. for example the house cricket (Gryllus cbmesticus) ; termites such as the eastern subterranean termite (Reticulitermes flavipes) and Rvmen-optera such as ants, for example the garden ant (Lasius niger.

The active compounds according to the present invention can he converted into the usual formulations, such as solutions, emulsions, suspensions, powders, pastes and granulates. These may be produced in known manner, for example by mixing the active compounds with extenders, that is, liquid or solid or liquefied gaseous diluents or carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing agents,and/ or foam-forming agents. In the case of the use of water as an extender, organic solvents can, for example, also be used as auxiliary solvents.

As liquid diluents or carriers, there are preferably used aromatic hydrocarbons, such as xylenes, toluene, benzene or alkyl naphthalenes, chlorinated aromatic or aliphatic hydrocarbons, such as chlorobenzenes, chloroethylenes or methylene chloride, aliphatic hydrocarbons, such as cyclohexane or paraffins, for example mineral oil fractions, alcohols, such as butanol or glycol as well as their ethers and esters, ketones, such as acetone, methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone, or strongly polar solvents, such as dimethyl formamide, dimethyl sulphoxide or ac tonitr a w liquids which would be gaseous at normal temperatures and pressures, e.g. aerosol propellents, such as halogenated hydrocarbons, e.g. freon.

As solid diluents or carriers, there are preferably used ground natural minerals, such as kaolins, clays, talc, chalk, quartz, attapulgite, montmorillonite or diatomaceous earth, or ground synthetic minerals, such as highly-dispersed silicic acid, alumina or silicates.

Preferred examples of emulsifying and foam-forming agents include non-ionic and anionic emulsifiers, such as polyoxyethylene-fatty acid esters, polyoxyethylene-fatty alcohol ethers, for example alkylarylpoly lycol ethers, alkyl sulphonates, alkyl sulphates and aryl sulphonates as well as albumin hydrolyzation products; and preferred examples of dispersing agents include lignin, sulphite waste liquors and methyl cellulose.

The formulations in general contain from 0.1 to 95 per ceit by weight of active compound, preferably 0.5 to 90 .

The active compounds can be used as such or in the form of their formulations or the use forms prepared therefrom, such as ready-to-use solutions, emulsions, foams, suspensions, powders, pastes, soluble powders, dusting agents, and granules. They may be applied in the customary manner, for example by squirting, spraying, atomising, dusting, sprinkling, fumigating, gassing, watering, dressing or encrusting.

The compositions may be diluted for actual application, and the concentration of active compound in the ready-to- "by weight.

The active compounds can also be used with good success in the ultra-low volume (ULV) method where it is possible to apply formulations of up to 95$ or even 100$ strength active compound by itself.

The invention therefore provides an insecticidal composition containing as activeingredient a compound according to the invention in admixture with a solid or liquefied gaseous diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent.

The invention also provides a method of combating insect pests which comprises applying to the insects or a habitat thereof a compound according to the invention alone or in the form of a composition containing as active ingredient a compound according to the invention in admixture with a diluent or carrier.

The invention also provides crops protected from damage by insects by being grown in areas in which, immediately prior to and/or during the time of the growing, a compound according to the invention was applied alone or in admixture with a diluent or carrier. It will be seen that the usual methods of providing a harvested crop may be improved by the present invention.

The compounds according to the invention, and the preparation and use of the compounds according to the invention, are illustrated by the following Examples.

Example A Myzus Test (contact action) To produce a suitable preparation of active compound, 1 part "by weight of the active compound was mixed with the stated amount of solvent containing the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Cabbage plants (Brassica oleracea) which had been heavily infested with the peach aphid (Myzus persicae ) were sprayed with the preparation of the active compound until they were dripping wet.

After the specified periods of time, the degree of destruction was determined as a percentage. 100$ means that all aphlds were killed and O means that none of the aphids were killed.

The active compounds, the concentrations of the active compounds, the evaluation times and the results can be seen from Table A.

Table A Myzus Test Active Compounds Active Degree of compound destruction' concenin after tration 1 day in £ (known) (known) Table A (continued) Myzus Test Active Com ounds Active Degree of ction Example B Rhopalosiphum test (systemic action) Solvent: 3 parts by weight of dimethylformamide Bmulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of the active compound was mized with the stated amount of solvent containing the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Oat plants (Ayena sativa) which had been strongly the preparation penetrated into the soil without wetting the leaves of the oat plants. The active compound was taken up by the oat plants from the soil and thus reached the infested leaves.

After the specified periods of time, the degree of destruction was determined as a percentage: 100 means that all the aphids were killed whereas Ofo means that none of the aphids were killed.

The active compounds, the concentrations of the active compounds, the evaluation times and the results can be seen from Table B.

Table B Hhopalosiphum Test Active Compounds Active com- Degree of (known) (known) 0.1 100 0.01 100 Table B (continued) Rhopalosiphum Test Active Compounds Active com- Degree of Example C Doralis-Test (systemic action) Solvent: 3 parts by weight of dimethylformamide Emulsifier: 1 part by weight of alkylaryl polyglycol ether To produce a suitable preparation of active compound, 1 part by weight of the active compound was mixed with the stated amount of solvent containing the stated amount of emulsifier and the concentrate was diluted with water to the desired concentration.

Bean plants (Vicia faba) which had been heavily infested with the bean aphid were watered with 20 ml each of the preparation of the active compound, so that the preparation of the active compound penetrated into the soil without wetting the leaves of the bean plants. The active compound was absorbed from the soil by the bean plants and thus reached the infested leaves.

After the specified periods of time, the degree of destruction was determined as a percentage: 100% means that The active compounds, the concentrations of the active compounds, the evaluation times and the results can be seen from Table C.

Table C Doralis Test (Systemic action) Active Compound Active compound Degree of concentration destruction in % by weight in % after 4 days C2H5-S02-CH2-^~¾-0-CO-N-(CH3)2 ' 0.1 0 (known) Le A 14 752-Isr Example 1: 55 g (0.3 mol) of 2-ethylsulphoxylmethyl henol (an' orange-coloured viscous oil, : 1.5665) were dissolved in 5OO ml of ether and 5 ml of 9 strength triethylamina were added. 20.5 g (0.36 mol) of methyl isocyanate were added dropwise at 20°C with occasional cooling. After stirring for a further 2 hours, the crystals were filtered off and 4Q g (5 .5$ of theory) of N-methyl~0~(2-ethyl- . sulphoxylmethyl-phenyl)-carbamic acid ester were obtained. The grey-white, granular crystals of limited solubility in water were recrystallised from ethyl acetate/ether (2:1; Ig/lO ml) and crystals of melting point 75°C. were obtained. Example 2: (2) 60 g (0.3 mol) of 2-ethylsulphonylmethylphenol (melting point 92°C from benzene-) were suspended, or partially dissolved, in 500 ml of ether. After adding 5 ml of tri-ethylamine, 20.5 g (0.36 mol) of methyl isocyanate were added dropwise at 20°C. No exothermic reaction was observed. After stirring for a further 2 hours, the product was filtered off and rinsed with ether. 69 g (89. $ of theory) of N-methyl-0-(2-ethylsulphonylmethyl-phenyl)-carbamic acid ester were obtained from ethyl acetate (l g/10 ml) in the form of colourless needles of melting point 123°C.

Examples 3 - 4 The following carbamates were obtained analogously to Examples 1 and 2 from 2-methylsulphoxylmBi;hyl-phenol (melting point 123°C) and 2-methylsulphonylmethyl-phenol (melting point 118°C).

Melting Yield point (# of theory)

Claims (9)

1. What we claim is:- 1. N-methyl-O-phenyl-carbamic acid esters of the general formula in which R represents alkyl with 1-4 carbon atoms and n represents 1 or 2.

2. Compounds according to claim 1 in which R represents methyl, ethyl or propyl.

3. The compound of the formula

4. The compound of the formula

5. The compound of the formula

6. The compound of the formula

7. A process for the preparation of a NHnethyl-O-phenyl-carbamic acid ester according to any of claims 1-6 in which in which R and n have the meanings given in claim 1, (a) is reacted with methyl isocyanate, or (b) is converted into the corresponding chloroformic acid ester with phosgene, and the ester is reacted with methyl-amine, or (c) is reacted with an approximately equivalent amount of phosgene to give the corresponding bis-phenyl-carbonate and the latter is split with methylamine.

8. A process according to claim 7 (a) in which the reaction is carried out in the presaioe of a base or catalyst. 9, A process according to claim 8 in which the base is a tertiary base. 10. A process according to claim 7 (b) in which the phosgene is used in excess. 11. A process according to claim 7 (b) 6r 10 in which the reaction with phosgene is carried out at a Pg below 7· 12. A process according to claim 7 (c) in which the reaction with phosgene is carried out at a pg of approximately 8. 13. A process according to any of claims 7-12 in which the reaction or reactions is or are carried out at 15 to 30°C. 14. A process according to any of claims 7-13 in which the reaction or reactions is or are carried out in the presence of a solvent. 43712/2 to claim 1, substantially as hereinbefore described in any of Examples 1-4. 16. Compounds according to claim 1 whenever prepared by a process according to any of claims 7-15· 17. An insecticidal composition containing as active ingredient a compound- according to any of claims 1-6 or 16 in admixture with a solid or liquefied gaseous diluent or carrier or in admixture with a liquid diluent or carrier containing a surface-active agent. 18. A composition according to claim 17 containing from 0.1 to 95 of the active compound by weight. 1

9. A method of combating insect pests which comprises applying to the insects or a habitat thereof a compound according to any of claims 1-6 or 16 alone or in the form of a composition containing as active ingredient a compound according to any of claims 1-6 or 16 in admixture with a diluent or carrier. 20. A method according to claim 19 in which a composition is used containing from 0.001 to 10 of the active compound, by weight. 21. Crops protected from damage by insects by being grown in areas in which, Immediately prior to and/or during the time of the growing, a compound according to any of claims 1-6 or 16 was applied alone or in admixture with a diluent or carrier.