DE1010314B - Herbicides - Google Patents

Description

Herbicidal agents The invention relates to herbicidal agents consisting of an ester of trichloroacetic acid with a polyglycol having a molecular weight from 300 to 400 dispersed in a carrier. It also concerns a method of using these agents in the selective control of herbal Growth.

Salts of trichloroacetic acid are already used in aqueous solutions Used to kill grasses and other plants. The salts, however, show the great one Disadvantage that you have to use them in strong doses per floor unit if they These doses are said to be effective, with intervals of 4 to 6 weeks during the growing season must be repeated to allow the grass to come back up impede. Another major disadvantage of the trichloroacetic acid salts is that that they are only slightly poisonous to broad-leaved plants, even if one apply them in fairly strong doses and repeatedly.

As a result, it can affect floor areas treated with such salts have been able to develop unwanted growth again and again if the salts are not be supplemented by herbicides, as opposed to broad-leaved plants are quite toxic.

It has now been found that esters of trichloroacetic acid with a polyglycol with a molecular weight of 300 to 400 have a remarkable effect in suppressing or killing grass alone or grass and broad-leaved plants - except those with woody tissues - even if these plants do fully grown above the ground. These polyglycol esters of trichloroacetic acid are also surprisingly effective as agents for pre-emergence treatment, as all types of plants are completely prevented from emergence or arise therein when the compounds are used before seed germination or before the seedlings emerge above the soil be restricted to a minimum. It has also been found that the growth of grasses can be almost completely prevented if the amounts of trichloroacetic acid polyglycol ester are measured correctly, while broad-leaved plant species are able to bloom at the same time. If the esters are used correctly, a selective effect appears to be exerted on the grasses, and at the same time these agents are relatively inert towards broad-leaved plants. Investigations have shown that the esters have a toxic effect on the root systems of the grasses as well as on the parts above the ground, so that the regeneration of the grasses is practically prevented.

In doses of about 1.1 to 3.9 g per square meter, based on the acid, are capable the means to effectively control the growth of grasses. Quantities on the order of magnitude from about 4.5 to 8.5 g per square meter, based on the acid, are present in the treatment effective for the emergence of the plants, and prevent the development of all types of plants. Quantities of about 5.7 to 11.3 g per square meter, based on the acid, kill all plant species with the exception of those that have a woody structure. The doses mentioned are recommended for use under normal weather conditions. When it is dry Season or dry climate are the ones necessary for the purposes mentioned Doses a little lower. Under such circumstances, 2.8 g per square meter, based on the Acid, to kill all vegetation on the ground surface.

The esters found useful for weed control will be in a known manner by esterification of trichloroacetic acid or a haloacetyl derivative this is made with a polyglycol with a molecular weight of 300 to 400. Preferably 1 to 2 equivalent weights of trichloroacetic acid or a trichloroacetic acid halide are used with 0.5 to 1 equivalent weight or more of the polyglycol (molecular weight 300 up to 400) implemented. For the preparation of the herbicidal esters, mixtures of Polyglycols can be used. The reaction is carried out with these higher molecular weights Polyglycols are best made in such a way that one slowly releases a trichloroacetyl halide to the polyglycol and the reaction with gentle heating (z. B. on the Steam bath).

The following esters were prepared for the purposes of the present investigations I. 1650 g (about 5.5 moles) of polyethylene glycol having a molecular weight of about 300 were placed in a four-necked flask equipped with a stirrer, thermometer, dropping funnel and condenser that with a gas scrubber too; Absorption of the released H Cl was related. 1000 g (about 5.5 mol) of trichloroacetyl chloride were added to the stirred glycol. The temperature rose to 75 to 80 °. When the addition of the trichloroacetyl chloride was complete, the reaction mixture was heated on a steam bath for 3 hours. The heated mixture was then gently evacuated to help remove dissolved gases. The cooled residue weighed 2464 g (about 99.7% of theory). analysis Calculated on monotrichloroacetate from Found Polyethylene glycol (molecular weight 300) Chlorine. . . . . . . . . . . 23.80 /, 23.450 /, In these and other esterification reactions, the trichloroacetyl chloride can be replaced by equivalent amounts of other trichloroacetyl halides, e.g. B. trichloroacetyl bromide, are replaced.

1I. 1800 g (about 6 moles) of the above polyethylene glycol were in the given device described. To the stirred glycol was slowly added 546 g (about 3 mol) trichloroacetyl chloride set. The temperature rose to about 70 °. To The trichloroacetyl chloride was added to the mixture on a steam bath for 21/2 hours heated. For the next 3 hours the mixture remained on the steam bath; a water jet pump was used to pull off and dissolve what had become free H C1 used. The monoester had predominantly formed, and only small amounts of the diester, both of which were dissolved in excess polyethylene glycol.

III. 1200 g (about 3 moles) of one were put into the device described Polyethylene glycol with a molecular weight of about 400 is given. These were slowly added with stirring 546 g (about 3 mol) of trichloroacetyl chloride. To complete addition of the trichloroacetyl chloride was carried out as in Example II described, proceed. It was mainly the monoester, the small quantities, that emerged of the diester contained.

IV. Of the polyethylene glycol with a molecular weight of about 300 earth molar is related to half as much as trichloroacetyl chloride. After removal the HCl formed during the reaction was not purified any further. The reaction product consisted predominantly of the diester, which contained only small amounts of the monoester.

Patent protection is not claimed for the manufacturing process.

The mono- and diesters formed during manufacture can be separated from one another separate; This is not necessary, however, as both types of esters have a herbicidal effect.

The monoesters dissolve or disperse in aqueous media in these by themselves; they are used on plants and soils in the form of aqueous dispersions or solutions. But they can also be used in relatively cheap liquid hydrocarbons, z. B. aromatic heavy gasoline and the like., Dispersed or dissolved. the Diesters, on the other hand, are found in liquid hydrocarbons, e.g. B. heavy aromatic Hydrocarbons and the like, soluble; however, they do not disperse in water by itself and consequently need a dispersant or emulsifier if one wants to use it in aqueous solutions. For the purpose of emulsification, all can known emulsifiers can be used. The nonionic ones are preferred. Examples suitable emulsifiers are: the sodium and potassium salts of fatty acids, known as hard and soft soaps; water-soluble salts of intra-molecularly rearranged Abietic acid, so-called resin soaps; Salts of the oxyaldehyde acids found in seaweed occur and are known as algin soaps; long-chain alcohols with 10 to 18 carbon atoms; water-soluble Salts of sulfated fatty acid amides, water-soluble esters of sulfated fatty acids; water-soluble alkyl sulfonates having 8 to 20 carbon atoms in the alkyl group; water soluble aryl sulfonates; water-soluble sorbitan monolaurate, palmitate, stearate and oleate; water-soluble polyepoxy laurate, palmitate, stearate and oleet, and many other. These dispersing and wetting agents are available under various trade names on the market and either individual compounds or mixtures of compounds of the same general group. The -aqueous dispersions and solutions of both the mono- as the diester or mixtures thereof can furthermore also contain adhesives or adhesives included to prevent them from being used as a herbicide Weather influences are removed from the soil or from the plants treated with it can. A polymeric agent acts as an excellent adhesive in an aqueous dispersion organic polysulphide, which forms an uninterrupted, translucent, rubber-like, microscopically fine film forms. An example of this type of adhesive is an aqueous dispersion of polymeric ethylene polysulphide obtained by the reaction of ethylene dichloride with an aqueous All @ alipolysulphide solution in the presence of a salt-resistant Emulsifier is produced.

The esters can also be mixed with other diluents Solutions, dispersions, pastes or dusts can be applied. These Solutions, dispersions and pastes can be made with any inert liquid carrier are, while the dusts usually with a finely divided inert solid, z. B. talc, flour, fuller's earth, clay or other non-alkaline, powdery, substances soluble or insoluble in water are produced.

The herbicidal activity of Esters I through IV was compared to sodium trichloroacetate using the different doses. In any case, the esters were at least equivalent to or superior to the salt in terms of killing or preventing renewed growth of grasses or broad-leaved plants. In this comparison, the amount applied per square meter was related to the acid equivalent of the compound. The test results are compiled in the following table Comparison of the polyglycol esters of trichloroacetic acid in their weed-killing effect Acid Initial Onset of Estimated Percentage Root Means equi-annihilation re-annihilation after damage remarks valent at famous g / qm tion in% after 3 weeks 5 weeks ilo weeks of the grasses Ester (I) in 11.3 100 - 100 100 100 dead very few broad-leaved ones around 2251 5.7 95 8 weeks 100 100 90 difficult very little grass Water 2.8 85 6 weeks 85 85 80 moderately light to moderate grass . _new education continuation Acid Initial Onset of Estimated Percentage Root Means Equal- Destruction Reclamation- Destruction after damage Remarks valent at famous g / qm tion in % after 3 weeks I 5 weeks I 10 weeks of the grasses Ester (II) in 11.3 100 - 100 100 100 dead moderately broad-leaved plants around 2251 5.7 90 6 weeks 90 95 95 hard regrowth Water 2.8 70 6 weeks 80 85 85 difficult - Ester (III) in 11.3 95 to 100 7 to 8 weeks. 95 95 95 heavy heavy broad-leaved around 2251 damage Water 5.7 90 6 weeks 90 80 75 moderate growth 2.8 70 2 weeks 40 30 I 20 very easy - Ester (IV) in 11.3 100 9 weeks 100 100 I 95 dead little broad-leaved around 2,251 5.7 95 9 weeks 95 95 y 95 dead - aroma- 2.8 95 8 weeks 95 95 90 heavy plants on every spot table Heavy- petrol I. Sodium 11.3 20 - 40 75 95 severe severe damage chlorine- 5.7 0 - 25 60 80 moderately of the broad-leaved acetate in around 2,251 2 1 8 0 - 10 0 0 nothing - water Sodium tri- 11.3 25 - 40 80 i 95 to chlorine- 100 severe severe damage acetate in 5.7 20 - 35 70 I 85 moderate around 4501 2.8 5 - 10 30 35 slightly of the broad-leaved water Aroma 2251 90 to 100 2 weeks 75 50 10 no complete new growth of grass table i damage Emphasis petrol, approximately From these results it can be seen that mono- and diesters with polyglycols, the molecular weight of which is between about 300 and 400, are particularly suitable for killing annual and perennial grasses and are therefore the preferred weedkillers of the invention. The esters with a polyethylene glycol, whose molecular weight is about 400, are at least as effective as equivalent doses of sodium trichloroacetate.

To determine the degree of effectiveness of the esters against Paragras (Panicum purpurascens) on trench edges, the esters were in amounts of 2.8, 5.7 and 11.3 g per square meter, based on the acidity, applied. The so-treated soil sites were compared to others on which equal doses of sodium trichloroacetate were applied had been. Untreated areas littered between the treated areas served as control points. 2 days after applying the herbicide put rain on the treated area (rain height about 8 cm). 3 weeks after Using the funds, the area was checked for grass growth. On all The parasitic grass was completely destroyed with 11.3 g ester per square meter treated areas.

Areas where Paragras can be found up to a height of 1 m and more fully developed require the use of doses of 11.3 g per square meter during extremely humid periods, or one must use several means Apply times in doses of 2.8 to 5.7 g per square meter.

The effect of weed-killing esters on onions, Radish, tomatoes and wheat seeds noted. Of each of the esters I through IV were 1% oige solutions prepared in which several of the named types of seeds for 1/2 hour have been immersed for a long time. Then the seeds were taken out, in petri dishes placed on moist filter paper, covered and incubated at 20 °. At the end of a week the onion seeds treated with esters III and IV did not germinate. The one with the Ester III treated wheat kernels showed retarded growth. Everyone else like that treated plant seeds appeared to germinate normally.

In order to determine the effect of herbicides on onion, wheat, To test tomato and radish seeds in the soil, numerous seeds were found in with arable soil filled pots inserted about 2 cm deep. Then 25 cc of a 1% solution were added of each agent to be examined poured over the floor. Germinated after 2 weeks only the radish seeds in the soil that had been treated with Ester I. Radish- and tomato seeds sprouted in the soil treated with Esters II and IV had been. Only the onion seeds germinated in the soil treated with Ester III not.

Claims (1)

PATENT CLAIM: Herbicidal agents, characterized by an ester of trichloroacetic acid with a polyglycol with a molecular weight of 300 to 400, which is in a carrier, e.g. B. a liquid carrier, is dispersed.