NO135472B - - Google Patents

Abstract

Substituted phenylthiocarbamates for use in herbicides.

Description

The present invention relates to new substituted phenylthiocarbamates for use in herbicides.

The herbicidal action of m-thiocarbanilates, e.g.

S-ethyl-m-(methylcarbamoyloxy)-thiocarbanilate, is known, e.g. from Norwegian patent 119-822 (corresponding to German publication no. 1,568-621).

Furthermore, there are known herbicidally active n-biscarbamates, e.g. a hyl-N-[3-(N1-st earylcarbamoyloxy)-phenyl]-carbamate

(German publication no. 1,567-151), as well as methyl-N-[3-(N<*->[2<*>,5'-dimethoxyphenyl]-carbamoyloxy)-phenyl]-carbamate and butyne-(l )-yl-(3)-N-[3 * -(N'-[3"-methoxyphenyl]-carbamoyloxy)-phenyl]-carbamate (British Patent No. 1,197-788) • Constitutionally analogous compounds are also known from the descriptions

to Danish patents no. 91,946, 127-363, 128-552 and 130,788, French patent no. 1,498-834 and Norwegian patent no. 119,822.

However, it has been shown that these active substances do not always have a sufficient herbicidal or selective effect.

It has now been shown that compounds of the general formula:

where R is methyl or ethyl, and

R 2 is allyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl,

neopentyl, phenyl, methylphenyl, dimethylpheny1 or chlorophenyl, exhibit an excellent herbicidal action against weeds while simultaneously sparing cultivated plants.

The herbicidal properties of the compound according to the invention are remarkable. They extend to the effect of a number of these compounds when used in both pre-emergence and post-emergence methods and thereby enable a fruitful application regardless of the time of vegetation.

Of the numerous weeds that can be combated with the compounds according to the invention, i.a. mention: Stellaria media, Senecio vulgaris, Matricaria chamomilla, Lamium amplexicaule, Galinsoga parviflora, Chenopbdium album, Amaranthus retroflexus and Setaria italica.

Most of the specified active substances also surprisingly prove to be selective towards a number of economically important cultivated plants so that they can be used to combat unwanted plants without harming these crops. thus, e.g. weed control is even carried out by the post-emergence method in maize, rice, wheat and other types of grain." Depending on the amount of weeds and the species composition of the weed flora, the application requirements for adequate weed control in useful plant crops amount to approx. &,5 -

5 kg of active ingredient/ha.

The compounds according to the invention are either used alone or in a mixture with other active substances. Possibly k-arr other plant protection or pest control agents, e.g. fungicides, nematocides or other agents, depending on the desired purpose, are added. An addition of fertilizers is £.eg. also possible.

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If an increase in the spectrum of action is desired, other herbicides can also be added, although, of course, selectivity is not always maintained. As herbicide-active mixing partners, e.g. active substances from the group of carbamic acid and thiocarbamic acid esters, the substituted anilines and anilides, triazines, amino-triazoles, diazines, such as uracils, e.g. 3-cyclohexyl-5,6-trimethyleneuracil, 1-phenyl~4-amino-5-chloropyridazone(6), aliphatic carboxylic acids and halocarboxylic acids, halogenated benzoic acids and phenylacetic acids, aryloxycarboxylic acids, hydrazides, amides, nitxyls, halocarboxylic acids, e.g. 2,2-dichloropropionic acid or its salts, tetrafluoropropionic acid or its salts, esters of such carboxylic acids, ureas, 2,3,6-trichlorobenzyloxypropanol and rhodan-containing agents.

Depending on the purpose of use, other substances can also be added, among these e.g. also non-phytotoxic additives,

which can give a synergistic increase in effectiveness with herbicides, such as wetting agents, emulsifiers, solvents, oily additives, etc.

Preferably, the active substances according to the invention or mixtures thereof are used in the form of preparations, such as powders, flow agents, granules, solutions, emulsions or suspensions, with the addition of liquid and/or solid carriers, respectively. diluents, and possibly wetting, binding, emulsifying and/or dispersing aids.

Suitable liquid carriers are e.g. water, aliphatic and aromatic hydrocarbons such as benzene, toluene, xylene, cyclohexanone, isophorone, and also mineral oil fractions.

As solid carriers, mineral soil is suitable, e.g. tonsil, silica gel, talcum, kaolin, attaclay, calsten, silicic acid and plant products, e.g. flour.

Surface-active substances can be mentioned: e.g. calcium lignin sulfonate, polyoxyethylene octylphenol ether, naphthalene sulfonic acids, phenol sulfonic acids, formaldehyde condensates, fatty alcohol sulfates and fatty acid alkali and alkaline earth metal salts.

The amount of the active substance or active substances in the different preparations can vary within wide limits. For example, the agent contains approx. 20 - 80% by weight active ingredient, approx. 80 - 20% by weight liquid or solid carriers, as well as possibly up to 20% by weight surface-

active substances.

The agent can be applied in different ways, e.g. with water as carrier in spray liquids in quantities of 100 - 1000 l/ha. For total eradication of weeds, the required spray liquid quantities can, under certain circumstances, be more than 1000 l/ha. An application of the agent in the so-called "ultra-low-volume method" is also possible as application of them in the form of so-called microgranules.

The compounds according to the invention can be prepared by methods known per se, e.g. from the corresponding chloroformate esters and aliphatic or aromatic amines or the corresponding phenols, resp. their salts and isocyanates or carbamoyl chlorides, optionally with the addition of catalysts and/or inorganic or organic tertiary bases or from the corresponding 3-nitrophenyl-N-alkyl-, N,N-dialkyl- or N-aryl carbamates by hydration. of the nitro group to the amino group e.g. using catalytically active hydrogen in methanol with subsequent reaction with chlorothioformic acid S-alkyl esters, optionally with the addition of an inorganic or tertiary organic base.

The production of the compounds according to the invention takes place by reacting compounds of the general formula: a) with carbamoyl chlorides of the general formula

in the presence of an acid acceptor, preferably an inorganic or tertiary one

organic base, or

by- with phosgene in the presence of eri acid acceptor to the corresponding klox-formic acid ester with subsequent reaction of this ester with an amine of the general formula:

c) when R2 is hydrogen, with isocyanates of the general formula: in the presence of a catalyst, preferably an organic base, or by catalytic reduction of compounds of the general formula: to the corresponding amine with subsequent reaction with a compound of the general formula:

in the presence of an acid acceptor to the desired end product.

The following example illustrates the preparation of the compounds according to the invention:

S-methyl-N-[3-(N*-n-ethylcarbamoyloxy)-phenyl]-thiocarbamate

A solution of 14.7 9 (0.08 mol) 3-hydroxycarbanilic acid S-methyl ester in approx. 6.1 g of ethyl isocyanate and 0.5 ml of triethylamine are added to 50 ml of tetrahydrofuran. After 15 hours at room temperature, the carbamate is precipitated by the addition of petrol (boiling point 65 - 8o°C).

Yield: 16.3 g = 8o% of the theoretical, m.p. 153 - 155°C.

The following table lists some of the compounds according to the invention.

They are mostly crystalline compounds that are soluble in organic solvents, such as e.g. acetone, cyclohexanone, isophorone, tetrahydrofuran, acetic acid ester, dimethylformamide and dimethylsulfoxyd.

The starting materials for the production of the compounds are known in and of themselves and can be produced by methods known in and of themselves.

The chloroformic acid-3-methylthio-carbonylamino-phenyl ester used as starting material (m.p.: 91 - 93°C) can e.g. is prepared in the usual way from the 3-hydroxythiocarbanilic acid S-methyl ester and phosgene with the addition of dimethylaniline in acetic acid ester.

From the following experiments, the herbicidal effect of the agents according to the invention can be seen compared to known agents.

Attempt 1

In greenhouses, the experimental plants listed below were treated by the pre-(a) or post-emergence method (b) with the agents according to the invention in a dosage of 5 kg of active substance/ha. The agent was sprayed evenly on the plants as an aqueous suspension at 600 l/ha. The comparator was also used as an aqueous emulsion at 600 l/ha.

The results show that only with the means according to the invention was a destruction achieved, or strong damage to the experimental plants, while these were not damaged by the known comparison agents.

The assessment took place 3 weeks after the treatment, with O meaning not damaged and k meaning completely destroyed.

Attempt 2

The plants listed below were treated at a growth height of 5 - 10 cm T with a comparison agent or the listed compounds according to the invention in a dosage of 1 kg/ha. The agents were sprayed evenly on the plants as aqueous emulsions with 500 l of water.

3 weeks after treatment, the agents according to the invention showed a strong

herbicidal effect with good compatibility with cultivated plants, while the comparison agent was ineffective.

Attempt 3

In connection with the post-emergence method, the plants listed in the following table were sprayed with the listed compounds in a dosage of 1 kg of active substance/ha. The agents were sprayed evenly on the plants as aqueous dispersions with 500 liters of water per hectares. lh days after the treatment, an assessment of the achieved result was made according to the following assessment scale:

0 = complete extinction

10 = no effect.

As can be seen from the results, the thiol carbamates according to the invention generally exhibited a stronger herbicidal effect than the analogous oxygen carbamates according to the descriptions of German publication no. 1.567.16<*>+ and French patent no. l.i+98.83^.

Claims (1)

Substituted phenylthiocarbamates for use in herbicides, characterized in that they are covered by the genes elle f ormel r where is methyl or ethyl, and R 2 is allyl, ethyl, propyl, isopropyl, butyl, sec-butyl, pentyl, neopentyl, phenyl, methylphenyl, dimethylphenyl or chlorophenyl.