DE2261431A1 - N-phenyl-5-bromopyrazolones - herbicides acting only against weeds without damaging culture plants - Google Patents

Abstract

Substd. N-phenyl-5-pyrazolones (I) Br-substd. in position 4 of pyrazolone ring, their derivs. and salts, pref. 1-phenyl- or 1-(4- or 2- or 3- -chlorophenyl)- or 1-(2,5- or 3,4-dichlorophenyl)-2,3-dimethyl- or 1-(cloro- or dichloro- or 3- or 4-nitrophenyl)3-Me-4-Br-pyrazolone-5, have selective activity against mono- and di-cotyledon weeds, e.g. alopecurus myosuroides, agrostis spica venti, poa anua, veronics, matricaria, stellaria media, voila tricolor, solanum migrum, polygonum, chenopodium, panicum etc. (I) or their hydrobromides are used esp. with extenders, as emulsion concentrates, spray powders or granulates opt. with fertilisers, pesticides and other herbicides. A synergetic effect is achieved on using (I) with 3-(4-chlorophenyl)-1-methoxy-1-methyl-urea and/or 2-Cl-4-ethylamino-6-isopropylamino-s-triazine.

Description

The invention relates to substituted N-Fhengl-5-pyrazolones, their salts and derivatives, as well as their use for eliminating undesired plants.

It is known according to DBP 1 112 855 that N-phenyl-3-methyl-4-chloro-pyraqzolone- (5) and N-phenyl-2,3-dimethyl-4-chlorpyrazolone- (5), also those substituted on the phenyl ring Derivatives and also the chlorohydrates of these compounds influence plant growth have. They acted as selective or total anti-trust agents, in particular usable in maize crops.

The object of the invention is to provide substances which also has a large tolerance range in a broader group of cultivated plants own and by destroying the weeds without damaging the cultivated plants cause.

The task is carried out by means of new substances of the same connection class desire, which are gekenuzeichmet that they are substituted in the 4-position with bromine are.

These new substances have a number of very undesirable berbicidal properties Properties that make them superior to the corresponding Chlo-connections. The user of such herbicidal compositions is thus for the first time in a position to meaningful Overcoming herbicide problems for which there has been no satisfactory solution. The mentioned Pigneschsften concern a surprisingly high selectivity in all Cetreideartan, also in Mals. Oilseed rape, beets, potatoes and other crops, being the commonly occurring weed species in reasonable amounts of the means Necessarily destroyed or not emerged when used in advance, noteworthy is the large tolerance range in both summer and winter cereals that the Practically eliminates risk of grain damage from overdose, practicing this Property means a very significant advantage, especially over the hitherto customary application of so-called growth substance herbicides from the class for this purpose of the phenoxycarboxylic acids, which are used as mache casserole herbicides in spring cereals but are dose-bound in an extremely narrow range. vines this substantial The growth agent herbicides show the risk of overdosing to the negative ones Influence, while the pyrazolones according to the invention clearly stimulate growth and yield. In addition, the compounds of the 2,4-D group show no activity against grass weeds such as black foxtail, stalk of wind and annual panicle, -In the summer grain, that is in weed removal is much more problematic than winter cereals, so-called contact herbicides are also used, mainly from the nitrated series Phenols. A crucial downside of these revenge herbicides is next to the toxicological Risk their ineffectiveness against grasses. All mentioned disadvantage omitted when using the pyrazolones according to the invention, which are excellent Effectiveness against weed grasses in cereals and which use it as pre-emergence herbicides do not let the weeds emerge first. The compounds according to the invention thus represent for the first time pre-emergence herbicides that are used in all summer cereal species are applicable. e described advantages also apply to numerous others Types of crops of plants including ornamental plants and rabbits. As special The high selectivity and tolerance range in oilseed rape and beetroot is pronounced to mention, a strong merbicidal effect of the 4-stwlaung brominated 1-phenyl-pyrazolones is among the monolotyledonous weeds against black foxtail (Alopecurus myosuroides).

Wind stalk (Agrostis spics venti) and annual panicle (Pos amun) observed, among the dicotyledonous weeds against honorary greens (Veronica species), chamomile (Matricaria species), Chickweed (Stellaria media), pansy (Viola tricolor), nightshade family (Solanum nigrum et al.). Knotweed (Polygonum species), white goosefoot (Chenopodium slbum), millet (Panicum species) and other economic weeds have been observed. The pre-sowing, pre-emergence and post-emergence methods are suitable as application methods, In most plant cultures, preference is given to the first two.

As a preparation form emulsion concentrates come in the same way, Wettable powder and granules are possible. The agents according to the invention can be used here also use in a mixture with fertilizers or other biologically active compounds. Mixing with other herbicidally active substances can be particularly advantageous be. In the case of selective use, this preferably applies to mixtures with smaller amounts Are such iserbicidal components too whose narrow tolerance range is too large Risk of harm includes when using admixtures of other herbicides synergistic effects can also be observed.

For the preparation of the 4-brominated N-phenylpyrazolones the following method is generally applicable for 1-phenyl-2,3-dimethyl-4-bromo-pyrazolone- (5): 188 g (1 wel.) 1-Phernyl-2, 3-dimethyl-p6razolon- (5) are dissolved in 600 ml of chloroform, slowly adds 51 ml of bromine (1So @,) 2 hol.) while stirring and cooling, leaves over I; eight and removes most of the solvent by evaporation. 326 g (85 ° 'of theory) 1-phenyl-2,3-dimethyl-4-bromo-pyrazolone- (5) -hydrobromide separate turn out as colorless to pale yellow crystals. The yield can be further increased Evaporation can be increased to almost loo C 'of the calculated wenge. The weakly hygrescopic Hydrobromide can be used as a herbicide after processing with inert and auxiliary substances. The free rast is particularly suitable for the production of emulsion concentrates, by dissolving the hydrobromide in warm water and adding alkalis easily is obtained in almost quantitative yield. The melting point is 119 ° (from alcohol).

Since the Ilydrobromide when standing in the air, when warming and when When recrystallizing, partially splitting off hydrogen bromide, they cannot be easily removed derstellen in analytically pure form or precisely define them by melting point. Therefore the following compounds are characterized as free bases by melting points.

Melting point 1-phenyl-2, 3-dimethyl-4-bromo-byrazolone- (5) 119 ° 1- (4-chlorophenyl) -2,3-dimethyl-4-bromo- 135 ° pyrazolone- (5) 1- (2-chlorophenyl) -2, 3-dimethyl-4-bromo-111 ° pyrazolone- (50 Melting point 1- (3-chlorophenyl) -2,3-dimethyl-4-bromo-132 ° pyrazolone- (5) 1- (2,5-dichlorophenyl) -2, 3-dirnethyl-4- 1790 bron-pyrazolone- (5) 1- (3,4-dichlorophenyl) -2,3-dimethyl-4- 1630 bromo-pyrazolone- (5) 1- (2-chlorophenyl) -3-methyl-4-bromo- 150 ° pyrazolone- (5) 1- (3-chlorophenyl) -3-methyl-4-bromo- 152 ° pyrazolone- (5) 1- (4-chlorophenyl) -3-methyl-4-bromo- 139 pyrazolone- (5) 1- (2,5-dichlorophenyl) -3-methyl-4-bromo- Decomp. from 175d pyrazolon- (5) 1- (3-nitrophenyl) -3-methyl-4-bromo- 125 ° pyrazolon- (5) 1- (4-nitrophenyl) -3-methyl-4-bromo dec. from 155 ° pyrazolone- (5) example 1: 500 g of 1-phenyl-2,3-dimethyl-4-bromo-pyrazolone- (5) lydrobromiC are niche, numbers and homogenization with 15o g of highly dispersed silica, 150 g of kaolin, 15o g calcium lignosulfonate and 5c g oleic acid methyl tauride or another powdery form Wetting agent processed in known Teise to a suspendable wettable powder.

On a last year heavily contaminated with wind stalk and annual risps, Heavy soil becomes the medium between sowing and emergence of spring barley as an aqueous suspension in a dosage of 2 kg of active substance / Hectares and applied in an amount of water of looo L / hectare.

The grain then runs practically free of black foxtail and other grass weeds. Even in the case of considerable overdevelopment, there is no damage to the grain observed. The yield not only exceeds that of the untreated comparison test by far, but is also significantly above aen with herbicides from the group the chlorophenoxycarboxylic acid treated comparative experiment, especially since these are known Herbicides only remove dicot weeds while by that Product according to the invention both dicotyledonous and monocotyledonous weeds or grass weeds can be selectively switched off.

Example 2: 400 g of 1- (p-chlorophenyl) -2, 3-dimethyl-4-bromo-pyrazolone- (5) dissolve in 500 ml of a mixture of methyl cellosolve and solvent naphtha (9: 1), add 100 g of oxyethylated castor oil as an emulsifier and thus get one in water Easily emulsifiable active ingredient concentrate.

Handled by Rs in the course of preparing an eat bed before eating out one the soil with an aqueous emulsion of the so manufactured means in a 2 kg active ingredient / wectar: Iooo 1 water / mectar corresponding dosage and works the remedy in the usual way about 3 - 4 cm deep into the tiredness. The im Rapeseed in the same process or later brought in run without any damage and without competition from weeds.

Example 3: A mixture of 1.5 kg of 1- (3,4-dichlorophenyl) -2. 3dinethyl-4-bromo-pyrazolone- (5) and 0.5 kg of 3- (4-chlorophenyl) -1-methoxy 1-methyl-urea (monolinuron) is after Example 1 to a.

50% active substance containing wettable powder prepared. Be application in the pre-emergence method for beet seed in the same way and quantity as in the example 1 stated, the seed runs without damage and without accompanying monocot or dicot weeds.

Example 4: A mixture of 1.6 kg of 1-phenyl-2, 3-dimethyl-4-bromo-pyrazolone- (5) -hydrobromide and 0.4 kg. 2-chloro-4-ethylamino-6-isopropylamino-s-triazine (atrazine) are in the same processing and application rate as in Example 1 in the pre-emergence method applied to spring wheat. The particularly vigorous growing grain remains free from weeds,

Claims (1)

P A T E N T A N S v R Ü C H E Substituted N-Phenyl-5-pyrazolones, their derivatives and salts, characterized in that they are on the pyrazolone ring in 4- Position are bromine-substituted. 2. 1-phenyl-2,3-dimethyl-4-bromo-pyrazolone- (5) 3. 1- (4-chlorophenyl) -2,3-dimethyl-4-bromo-pyrazolone- (5) 4. 1- (2-chlorophenyl) -2,3-dimethyl-4-bromo-pyrazolone- (5) 5. 1- (3-chlorophenyl) -2,3-dimethyl-4-bromo-pyrazolone- (5) 6. 1- (2,5-dichlorophenyl) -2,3-dimethyl-4-bromo-pyrazolone- (5) 7. 1- (3,4-dichlorophenyl) -2,3-dimethyl-4-bromo-pyrazolone - (5) 8. 1- (2-chlorophenyl) -3-methyl-4-bromo-pyrazolone- (5) 9. 1- (3-chlorophenyl) -3-methyl-4-bromo-pyrazolone- (5) 10. 1- (4-chlorophenyl) -3-methyl-4-bromo-pyrazolone- (5) 11. 1- (2,5-dichlorophenyl) -3-methyl-4-bron-pyrazolone- (5) 12. 1- (3-nitrophenyl) -3-methyl-4-bromo-pyrazolone- (5) 13. 1- (4-nitrophenyl) -3-methyl-4-bromo-pyrazolone- (5) 14th Use of the substances according to one or more of Claims 1 to 13 or of the hydrobromides these substances, preferably together with extenders in the form of emulsion concentrates, Wettable powders or granules, possibly mixed with fertilizers, pesticides and other herbicides, as a means of eliminating or preventing undesirable Plant growth, especially in plant crops. 15. Application of the substances according to one or more of claims 1 to 13 according to claim 14, characterized in that for the purpose of obtaining a synergistic effect 3- (4-chlorophenyl) -1-methxy-1-methyl-urea and / or Z-chloro-4-ethylamino-6-isopropyl-emine-striazine is used in a mixture with.