CH558141A - 3-bromo-4-isopropylphenylureas - Google Patents

Abstract

Ureas of formula (where R is H, (1-4C) alkyl, (1-4C) alkoxy (2-4C) alkenyl, or (2-4C) alkynyl, all opt. substd. e.g. by hal) are biocides and selective herbicides. (I) are prepd. by condensing 3-bromo-4-isopropylphenyl isocyanate with a methyl amine or an O,N-methyl hydroxylamine.

Description

  

  
 



  In the main patent no. 537 148, the use of phenylurea derivatives of the formula A
EMI1.1
 for weed control in cereal crops.



  In this formula, R denotes a methoxy group, a C1C4-alkyl or a C2-C4-alkynyl group, while X stands for a hydrogen or chlorine atom.



   The present invention relates to the use of similarly structured phenylurea derivatives of the formula
EMI1.2
 for combating weeds in cereal crops.



   In the formula (I), R stands for hydrogen, methoxy, C-C4-alkyl or C2-C4-alkynyl and X for hydrogen or halogen. Excepted from this scope are those compounds that are protected in the claim of the main patent. There are radicals such as C1-C4-alkyl groups. B. methyl, ethyl, n- or i-propyl or n-, sec.- or tert.



  To understand butyl. A C2-C4-alkynyl group includes radicals such as. E.g. ethynyl, 1-propynyl, 2-propynyl, sec-butynyl.



   Compounds of the formula are of particular importance
EMI1.3
 where R 'is hydrogen, methoxy, C1-C4-alkyl and X' is bromine.



   The ureas of the formula (I) are prepared by methods known per se, e.g. B. by reaction of a corresponding phenyl isocyanate with an N, N-methylalkylamine or O, N-methylalkylhydroxylamine.



   The selective herbicidal action can be achieved both pre-emergence and post-emergence and is mainly observed in cereals (such as, for example, wheat, oats, barley, rice). The application rates can vary within wide limits z. B. between 0.1 to 10 kg of active ingredient per hectare, but preferably 0.5 to 5 kg per hectare.



   The active ingredients of formula I are also used to otherwise influence plant growth, eg. B. to accelerate the ripening of plants through premature drying, also to increase the fruit set, delay flowering, to extend the shelf life of harvested products or to make frost resistant.



   The active ingredients of the formula I can be used alone or together with suitable carriers and / or other additives. Suitable carriers and additives can be solid or liquid and correspond to the substances customary in formulation technology, such as. B. natural or regenerated mineral substances, solutions, thinners, dispersants, wetting agents, adhesives, thickeners, binders or fertilizers. Further biocidal compounds can also be added. Such biocidal compounds can e.g. B.



  the class of ureas, saturated or unsaturated halogenated fatty acids, halogenobenzonitriles, halogenated benzoic acids, phenoxyalkylcarboxylic acids, carbamates, triazines, nitroalkylphenols, org. Phosphoric acid compounds, quaternary ammonium salts, sulfamic acids, arsenates, arsenites, borates or chlorates.



   Solvents, such as alcohols in particular, eg. B. ethyl or isopropyl alcohol, ketones such as acetone or cyclohexanone, aliphatic hydrocarbons such as kerosene and cyclic hydrocarbons such as benzene, toluene, xylene, tetrahydronaphthalene, alkylated naphthalenes, and also chlorinated hydrocarbons such as tetrachloroethane, ethylene chloride, and finally, mineral and vegetable oils above substances in question.



   Aqueous preparations are dispersions in general and emulsions in particular.



  The active ingredients are homogenized in water as such or in one of the abovementioned solvents, preferably by means of wetting or dispersing agents. Quaternary ammonium compounds may be mentioned as examples of cationic dispersants; of anion-active z. B. soaps, aliphatic long-chain sulfuric acid monoesters, aliphatic-aromatic sulfonic acids, long-chain alkoxyacetic acids; of nonionic polyglycol ethers of fatty alcohols or p-tert. Alkylphenols with ethylene oxide. On the other hand, concentrates consisting of active ingredient, dispersant and possibly solvent can also be produced. Such concentrates can be z. B. dilute with water and are then available as emulsions or suspensions.



   Dusts can be produced by mixing or co-grinding the active substance with a solid carrier. As such come z. B. in question: talc, diatomaceous earth, kaolin, bentonite, calcium carbonate, boric acid, tricalcium phosphate, but also wood flour, cork flour, coal and other materials of vegetable origin.



  The active ingredients can also be absorbed onto the carrier substances using a volatile solvent. By adding wetting agents and protective colloids, pulverulent preparations and pastes can be suspended in water and made usable as sprays.



   In many cases, the use of granules for the even delivery of active ingredients over a longer period of time is advantageous. This can be done by dissolving the active ingredient in an organic solvent, absorption of this solution by granulated mineral, e.g. B. Make attapulgite or SiO2 and remove the solvent. The content of active ingredient in the agents described above is between 0.1 and 95%.



   Preparation Example 1 N-4-Isopropyl-3-bromophenyl-N ', N' -dimethylurea
A. A solution of 117 g of 4-isopropyl-3-bromaniline in 100 ml of ethyl acetate was added dropwise at -10 to -5 ° C. to a solution of 200 g of phosgene in 1 liter of ethyl acetate. The cooling bath was removed and left at room temperature for 20 hours after-react before the reaction solution was fractionated, giving 121 g of 4-isopropyl-2bromophenyl isocyanate with a boiling point of 131-135 ° C./15 mmHg.



   B. 55 g of 4-isopropyl-3-bromo-phenyl isocyanate were added dropwise to a solution of 200 ml of dioxane and 100 ml of 40% strength aqueous dimethylamine solution. The product was precipitated by adding 1 liter of ice water and recrystallized from alcohol. The urea of the formula was obtained
EMI2.1
 (Active ingredient no. 1)
Production example 2
60 g of 4-isopropyl-3-bromophenyl isocyanate were added dropwise to a solution of 100 ml of benzene, 100 ml of hexane and 30 ml of O, N dimethylhydroxylamine. The reaction solution was then evaporated. The compound of the formula was obtained
EMI2.2
 (Active ingredient No. 2)
Similarly, when using 4-isopropyl-3-bromophenyl isocyanate and the corresponding amines, the following ureas were obtained:
EMI2.3
 No.

  R 'm.p. C
EMI2.4


<tb> <SEP> CH3
<tb> 3 <SEP> -CH <SEP> 110-111
<tb> <SEP> C = CH
<tb> 4 <SEP> -C4H9 (n) <SEP> 64
<tb> 5 <SEP> H <SEP> 114
<tb> 6 <SEP> -C3H7 (n) <SEP> 77- <SEP> 79
<tb> and the compound obtained by an analogous reaction of 3-chloro-4-isopropylphenyl isocyanate and monomethylamine
EMI2.5

Formulation example dust
Equal parts of an active ingredient of the formula I and precipitated silica were finely ground. By mixing it with kaolin or talc, it was possible to produce dusts with a preferably 1-6% active ingredient content.



  Wettable powder
To produce a wettable powder, for example, the following components were mixed and finely ground: 50 parts of active ingredient according to the present invention 20 parts of highly adsoptive silica 25 parts of Bolus alba (kaolin)
1.5 parts of 1-benzyl-2-stearyl-benzimidazole-6,3 'disulfonic acid sodium
3.5 parts of reaction product from p-tert. Octylphenol and ethylene oxide.

 

  Emulsion concentrate
Easily soluble active ingredients were formulated as an emulsion concentrate according to the following procedure: 20 parts of active ingredient 70 parts of xylene 10 parts of a mixture of a reaction product
Alkylphenols with ethylene oxide and calcium dodecylbenzenesulfonate were mixed. When diluting with water to the desired concentration, a sprayable emulsion was created.



  Granules
7.5 g of one of the active ingredients of the formula I were dissolved in 100 ml of acetone and the acetone solution thus obtained was added to 92 granulated attapulgite. The whole was mixed well and the solvent removed in a rotary evaporator. Granules with an active ingredient content of 7.5% were obtained.



   Biological example of herbicidal effect
The following types of plants were sown in the greenhouse: Triticum vulgare (= wheat), Zea mays (= maize), Oryza (= rice), Hordeum (= barley), Avena (= oats), sorghum, soy, Alopecurus, Poa, Amaranthus, Panicum , Chrysanthemum, Calendula, Sinapis, Stellaria, Digitaria, Galium, Beta (= sugar beet), Brassica (= cabbage) and Ipomoca.



   The post-emergent treatment of the plant species mentioned was carried out with a 1% aqueous solution of the compounds about 10-12 days after sowing, in the 2-3 leaf stage, at an application rate of 1 kg or 2 kg of active substance per hectare. The evaluation took place about 20 days after the treatment and led to the result shown in the table below.



   The pre-emergent treatment was carried out with 1 kg AS / ha, but already 24 hours after sowing.

 

  Active ingredient no. 1 1 2 3 4 5 post pre post post post post plant species 1 kg / ha 2 kg / ha 1 kg / ha 1 kg / ha 1 kg / ha 2 kg / ha Triticum 1 3 1 1 2 1 Hordeum 1 - - 2 - Avena 2 - - - 2 Zea 1 1 2 1 2 1 Oryza - 2 - - 1 2 Soy - 1 - - - - Digitaria 9 9 9 7 8 8 Sorghum 8 8 9 7 - Panicum - 9 9 - - Poa 9 9 9 - 7 7 Alopecurus - 9 8 8 - Beta 9 9 9 9 9 9 Galium - - 7 - - 7 Calendula 9 9 9 9 9 9 Chrysanthemum 9 8 9 - 7 8 Sinapis 9 8 9 9 9 9 Brassica 9 9 9 9 7 9 Ipomoea - 8 9 - 8 9 Stellaria 9 9 9 9 9 9 Amaranthus 9 9 9 9 9 9 Rating:
1-3 = plants not or hardly affected 9 = plants dead 4-6 = moderate damage - = not tested
7-8 = severe damage

 

Claims (1)

PATENT CLAIM Use of a compound of the general formula EMI3.1 where R is hydrogen, methoxy, C1-C4-alkyl or C2-C4-alkynyl and X is hydrogen or halogen, with the exception of the compounds covered by the claim of the main patent as a selective herbicide for weed control in cereals. SUBClaim Use according to patent claim of a compound of the formula EMI3.2 where R 'is hydrogen, methoxy or C1-C4-alkyl and X' is bromine.