IL33727A - Amidothionophosphoric acid esters as herbicides - Google Patents

Description

Amidothionophosphoric aoid esters as herbicides ■ AlU3MT?AIlR¾BBg BAYER AKTIENGESE1ISCHAPT The present Invention relates to the use as a herbicide of a certain amidothionophosphoric aoid ester. The invention provides a method of combating weeds which comprises applying to the weeds or a habitat thereof the compound of the formula alone or in admixture with a solid or liquid diluent or carrier.

According to British Patent No. 659»682, it is known that compounds of the type of that used in the present invention possess insecticldal and fungicidal activities. However, that patent indicates only thac those compounds have insecticidal and acarlcidal efficacy and are also effective for the control of harmful fungi on plants and can be used as spraying preparations. There is no description of a test example showing their efficacy, and no indication of any ho bicidal activity. There is also no mention of the applicability of the compounds to soil or any reason to expect herbicldal activity.

A compound of U.S. Patent No. 3,074,790, 0-(2,4· dichlorophenyl)-0-methyl-H-iso-propylphosphoroamidothioate, possesses activity as a herbicide.

It has now been found that 0-(2-nitrophenyl)-0-ethyl- N-isopropylphosphoroaraidothioate of the structural formula (I) has strong herbicldal activity, especially against weeds in paddy fields; weeds of the Graminae family, broad leaved weeds and perennial weeds. Moreover it shoxfs remarkably good selective herbicldal activity, for example in exhibiting little or no soil treatment herbicide in the control of weeds in paddy fieldsf As shown "by Example A herein, the compound of fonaula (I) according to the present invention is also superior in rospeot of its above mentioned properties, to 0-(2-nitrophenyl)-0-methyl-N-iso-propylphosphoroajnidothioa e disclosed in German Patent iio. 1,245»952 (corresponding to Israeli Patent No. 26698). 33727/2 The compound used in the present invention is obtained easily and with good yields by reacting O-ethyl-N-isopro pyl-amido-thionophosphoric acid ester halide with 2-nitrophenpl, preferably in the presence of an acid binding agent, or by reacting it with a salt of 2-nitrophenol as shown by 'the following reaction scheme: in which Hal is a halogen atom, preferably a chlorine atom, and Me is a hydrogen atom, alkali metal atom or ammonium radical. (1 Example 1 illustrates the preparation of the compound used in the present invention.

Example 1 14 g (0.1 mol) of 2-nitrophenol were dissolved in 100 ml of ac¾9tonitrile and 14- g of anhydrous potassium ca-rbonate were added to the solution. 20.2 g (0.1 mol) of 0-ethyl-N-iso-propyl-amidothionophosphoric acid ester chloride were added dropwiBe at 50-60°G, with vigorous stirring. The inorganic salt produced was filtered off and the filtrate was distilled to remove the solvent. The residue was dissolved in 100 ml of benzene and the benzene solution was washed with V/o aqueous solution of sodium carbonate, which was dried over anhydrous sodium sulphate. After distillation off of the benzene, 25.3 g of 0-( 2-nitrophenyl)-0-ethyl-N-iso- . propylphosphoroamidothioate were obtained.

The active compounds used according to the present invention can be 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 diluents or carriers, optionally with the use of surface-active agents, that is, emulsifying agents and/or dispersing 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 or benzene, chlorinated aromatic hydrocarbons, such as chlorobenzenes, paraffins, such as mineral oil fractions, alcohols, such as methanol or butanol, or strongly polar solvents, such as dimethyl formamide or dimethyl sulphoxide, as well as water.

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

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

The compounds can be applied in admixture with such adjuvants generally used for agricultural chemicals as spreaders, emulsifiers, wetting agents, adhesive agents, etc. Further, they can be applied in admixture with other herbicides, for example phenoxy compounds, chlorophenol compounds, carbamate compounds, diphenyl ether compounds, urea compounds or triazine compounds, and also with plant growth regulators, insecticides, acarici-des, nematocides, fungicides and other agricultural chemicals and fertilizers. Mixed application especially with phenoxy herbicides, for example esters of MCP ( 2-methyl-4-chlorophenoxy acetic acid), is effective and gives rise to synergistic effects.

The method of the present invention is illustrated by the following Examples 2-6.

Example 2 $ of the compound of the present invention and 95$ of a mixture of talc and clay are formulated into a dust by mixing and crushing, and used by dusting as such.

Example 3 $ of the compound of the present invention, 75$ of a mixture of Zeeklite and clay, 3$ of sodium alkylbenzene sulphonic acid and 2$ of sodium dinaphthyl-methane disulphonic acid are formulated into a wettable powder by mixing and crushing and applied diluted with water .

Example 4 of the compound of the present invention, 75% of xylol and $ of Sorpol (trade name of a product of Toho Kaga'ku Kogyo K.K. ) are formulated into an emulsifiable concentrate by mixing and stirring, and applied diluted with water.

Example 5 The compound of the present invention is dissolved in xylol while heating. The solution is sprayed onto clay granules while rotating and mixing so that about 10$ of active ingredient is incorporated in the granules. The granular formulation is used by scattering as such on the surface of soil.

Example 6 Three parts of the compound of the present invention, 1.5 parts of ethyl ester of MCP (2-methyl-4-chlorophenoxy acetic acid), and 95.5 parts of bentonite are mixed well. The mixture containing of paddy fields.

The compositions of the present invention generally contain 0.1 - 95% by weight, preferably 0.5-90$ by weight, of active compound.

The application may be carried out by ordinary methods, for example watering, spraying, atomizing, dusting or scattering.

The most suitable application time is before the germination of the weeds to be eradicated. When application is carried out mainly before the germination of cultivated plants, the general conditions of cultivation are not so important, but the quantity per unit area of active compound to be applied and the application method are important.

The quantities of the active compound to be used according to this invention may vary within a fairly wide range. They depend upon various factors, for example the conditions of cultivation, soil, weeds and weather as well as the purpose of application. The compound of the present invention tends to show non-selective her-bicidal action when used in an amount of more than 500 g per 10 a. in, paddy fields or dry fields, but tends to show selective herbi-cidal action when used in smaller amounts.

The outstanding herbicidal action of the compound of the present invention as well as its aiperiority as a herbicide to -the previously known compounds is clearly shown by the following Examples A and B.

Example A. Test against weeds of paddy fields Test method : After filling up pots of 1/5,000 a. with soil of paddy field, paddy rice seedlings (Kinmaze variety) at the 3 to 4 leaves stage were transplanted under inundation conditions. After the seedlings were rooted, barnyardgrass, seeds of broad-leaved weeds and spikerush were planted. The compounds of the present invention formulated into emulsifiable concentrate or wettable powder were sprayed in amounts of 500, 250 and 125 g as active ingredient per 10 a. After three weeks, the herbicidal effect against barnyard-grass, spikerush and broad-leaved weeds and the phytotoxicity to the paddy rice were investigated. The results are in Table A.

Valuation: Herbicidal efficacy Phytotoxicity highest efficacy 5 highest phytotoxicity 4 big efficacy 4 big phytotoxicity 3 medium efficacy 3 medium-big phytotoxicity 2 small efficacy 2 medium phytotoxicity 1 slightest efficacy 1 small phytotoxicity 0 no efficacy 0 no phytotoxicity Table A Herbicidal efficacy against weeds of paddy fields and phytotoxicity to rice Quantity η„„„Λ„„, of active Herbicidal effect Phytotoxici Compound irJgred. ients barnyard- spikerush broad-leaved rice g/10 a grass weeds Compound 500 5 5 5 0 of pres250 ent 5 5 5 0 invention 125 5 4-5 5 0 500 A 5 4 4 0 (Comparison) 250 4 3 3 0 125 2 1 2-1 0 PCP( Commer500 5 3 5 0 cial product; 250 Compari son) 3 0 2 0 125 1 0 0 0 NIP( Commer500 5 5 5 3 cial product; Comparison ) 25Ο 5 5 5 1 125 3 1 2 0 Non-treatment _ 0 0 0 0 Broad-leaved weeds are; Monochoria vaginalis, Rotala indica, Lindernia pyxidaria, Dopatrium junceum, etc.

PCP: pentachloro henol (Commercial product).

NIP: 2 , -dichlorophenyl- ' -nitrophenyl ether (Commercial product). : 0-( 2-nitrophenyl)-0-methy1-N-isopropylphos phoroamidothioate.

Example B. Test against weeds of upland fields :^ Test method: After filling up pots of 30 x 30 cm with soil of diluvial volcanic ashes, seeds of the undermentioned weeds, upland rice (Hataminori variety), and vegetables were sown. After covering with soil, the compounds of the present invention in. the formulation of the emulsifiable concentrate or' wettable powder were sprayed ori the surface of soil in amounts of 400, 200 and 100 g of active ingredient per 10 a. After 3 weeks, herbicidal efficacy against . all the kinds of weeds and phytotoxicity to upland rice. and various vegetables were investigated. The. results are in Table B.

Valuation: Herbicidal efficacy Phytotoxicity highest efficacy . 5 highest phytotoxicity 4 big efficacy 4 big phytotoxicity 3 medium efficacy 3 medium-big phytotoxicity 2 small efficacy 2 medium phototoxicity 1 slightest efficacy 1 small phytotoxicity 0. no efficacy 0 no phytotoxicity NIT 23 - 9 - Table B . Test results of herbicidal efficacy against weeds of o various cro s Compound Quantity Herbicidal efficacy of a.i. gAO barnyard- finger-- dent wild common u a grass grasa foxtail amaranth purslane r Compound of 400 5 5 5 5 5 present 200 5 5 5 5 5 invention 100 5 4-5 4-5 ; . 5 .; · 5 B 400 5 5 • 5 · l 2 (Comparison) 200 4-5 4 4 . 0 0 ' 100 ' . 3 3 3 - 0 0 ■ CAT (Commer100 5 5 5 5 5 cial product; 50 4 4 5 5 ' 5 Comparison) NIP (Commer¬ 400 cial product; 5 5 5 5 5 . 200 Comparison) 5 5 4 5 5 Non-treatment ' - 0 0 0 0 ' 0 Notes: 1) CAT: 2--chlorO" -4, 6-bis( ethylamin □ )-l,3,5-tri 0-( 2, 4-dichlorophenyl)-0-methyl-N-iso- NIT 23 - 10 -

Claims (1)

1. insufficientOCRQuality