CA1079729A - Herbicidally active 1,2,4-triazin-5-one derivatives - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A herbicidally active 1,2,4-triazin-5-one derivative of the formula:

Description

- ~07~729 The present invelltion relates to a 1,2,4-triazinone derivative, a process for l~roducing it and to herbicidal agents containing said 1,2,4-triazin-5-one derivative as the active component as well as to tile use of said 1,2,4-triazin-5-one derivative or of agents containing -them for the control of un-desired plant growth.
According to the present invention there is provided a triazinone derivative corres~onding to the formula:

O :, 11 `, CE~ C

/ ~ / \ (I) C2~15 N \ ~ C - SC~13 N

ie 4-amino-6(1-ethyl-cyclo propyl)-3-methylthio-1,2,4-triazin-5-one.
This application is a divisional application of copend- ~ -ing application No. 307,630 filea July 19, 1978. In said copend-ing application ~here is provided a herbicidally active, 1,2,4-triazin-5-one oE formula I, except being substituted in the 6-position by l-methyl cyclopropyl.
The product can be prepared by means of a process des-cribed by Dornow et al (Ber. 97, 2173-79, (1964j). According to this process an alkyl- or aryl-glyoxylic acid is condensed with thiocarbohydrazide to a 6-aryl- or alkyl- substituted 4-amino-3-thiono-1,2l4-triazin-5-one and subsequently reacted by means of a methylating agent to the 3-methyl-mercapto derivative.
Methyl iodide, methyl bromide or dimethyl sulphate in a basic medium can be used as methylating agents. However, when apply-ing this reaction to the production of the compound acc:oxding lO~ Z9 to the invention a tertiary alkyl ~mide of the corresponding glyoxylic acid must be used as the starting material. The rcaction can be represen-ted by the following equation, wherein R represents a tertiary alkyl radical containing 4 to 18 carbon atoms, particularly the t-butyl, t-amyl or t-octyl radical:

/ \ /

2 C - CO - CON * H2N-NH-CS-NH l~H2 O
, ~ ,g~
H C Cll C N - NH2 c2~s \ W / = S ., , ...
H :

CH ll

3 > H C/ ~ C~lC / \ N - NH2 The reactions are carried out preferably in polar sol-vents, such as methanol, ethanol, dimethyl formamide, dimethyl sulphoxide, water or mixtures thereof, at temperatures between 0C and the boiling point of the solvent or of the mixtures.
The reactions of the thiocarbohydrazide with the ter-tiary alkyl arnides of the (l-ethyl-cyclo~ropyl)-glyoxyl:ic acids are carried out in the presence of an acid, preferably sulphuric acid, or hydrochloric acid, that is to say, in arnounts corres-lO~g7Z9 ponding at lcast to the equivalent amount of amide.
The methylation is carried out in a manner known perse, preferably with methyl iodiode or methyl bromide.
r~he (l-ethyl-cyclopropyl)-glyoxylic acid-tert.-al~yl amides can ~e obtained, for example, by condensation of tlle 1-ethyl-cyclopropane carboxylic cyanides with a tcrtiary alcollol or with an alkene in an acid medium. This reaction is carried out essentially under the conditions of -the so-called "Ritter"
reaction or "Graf-Ritter" reaction (JACS 70, 4045 (1948), JACS
70, 4048 (1948)). Particularly glacial acetic acid or dichloro me-thane or ether, as for example, dibutyl ether, can be used as solvents.
The acyl cyanide can be obtained in turn from the corresponding acyl halide. For cxample, it can be obtained by means o~ the process oE the German Patent Application P 27 08 183.0 by reaction with CuCII at temperatures between 50 and 180C
in a mixture of approximately 1 to 10 parts by weight of an inert carboxylic nitrile and approximately 0.5 to 20 parts by weight of an inert organic solvent, for example, dioxane. According to the German Patent P 27 08 182.9 this production can also beso carried out that a mixture of approximately 0.1 to 5 parts by weight of ' alkali metal cyanide and approximately 0.05 to 2 parts by weight of a copper~ salt is used and that the production is likewise carried out in the presence of an inert carboxylic nitrile.
The 1,2,4-triazon-5-one derivative according to the invention which has the formula I afects the growth of plants.
In particular it has excellent herbicidal properties. It serves primarily for the control of weeds. However, because of its favourable desicating and defoliating action it can be used as a harvesting aid in cultures such as cotton and potatoes.
In the control of mono- and di-cyteledonous weeds the active substance of the formula I exhibits even when applied in small amo~nts, an excellent herbicidal effect on undesired vegeta~ion while distinctly sparing a number of useful plant cultures and in this respect it surprisingly i5 superior to structurally similar known l,2,4-triazin-5-c)ne cleriva-tives.
This also covers the kinds of weeds which are difficult -to control.
The tria~inone according to the invention has very good properties with respect to Gramineae such as millet or millet-like plants and fox-tail grasses (Alopecurus sp.).
The general e~fec-tiveness of the triazones is known, for example, that of the compound 4-amino-6-t-butyl-3-methyl-thio-1,2,4-triazin-5-one. Tlle novel compound differs from the latter compound primarily in the prcemeryence tcst at average concentrations in that it ac~5 much more selectively in a num-ber of us~Eul plant culture~s, as for example, in corn, soybean, rye, barley and oats, and it also differs by its effectiveness against Gaiium aparine.
The compound of the present invention can be applied with equally good results in the usual formulae after the emer-gence of the plants (postemergently) and particularly preemer-gently. The amounts used for the active substance accorcling to the invention vary within wide limits and are surprisingly low irrespective of purpose and place of applicakion, culture, type o~ weed and their spread, climatic conditions, etc. In light soils the triazinone derivative according to the present inven-tion usually is effective when applied in amounts as low as 0.1kg per hectare. It is preferably applied in amounts of 0.5 to 2.0 kg per hectare. In heavy soils rich in humus and in adsorp-tive soils higher amounts are required. When applied in amounts of up to and exceeding 3.0 kg per hectare the total herbicidal action of the compound outweighs the selective action.
The ~xamples hereafter illustrate the process for pro-ducing the novel compound having the formula I. The temperature~

lOt797~9 are expressed in deyrees of Celsius.
Example l a) Production of the l-ethyl-cyclopropane carboxylic cyanide 90.5 g of l-ethyl-cyclopropane carboxylic cllloride are stirred in l~O ml of acetonitrile ~ trichloroethylene = l:l Wit]
79.3 g of CuCN for 12 hours at 80C. The cooled suspension is filtered, the filtrate is to-tally concentrated and the residue is distilled. 65 g of colorless l-ethyl-cyclopropyl carboxylic cyanide having a b.p.60 mbar of 88C are obtained.
b) Production of the (l-ethyl-cyclopropyl)-glyoxylic tertiary butyl amide 10 g of a 98% H2S04 are added dropwise to a solution of 12.3 g of l-ethyl-cyclopropane carboxylic cyanide in 13 g of t-butanol and 13 ml of methylene chlorid~ within 10 minukes at O to $C. The solut:Lon is then st~rred Eor ~ hours ~t: room temperature, whereupon it is mixed with 2 ml of ~I20 and stirred for further 30 minutes. The pH of the solution is adjusted to 6 with 80 ml of ZnNaOH and the organic phase is separated. After removing the solvent the residue is crystallized from 50 ml of petroleum ether (b.p. 40 to 65C) at 50C. Thus, 13.1 g of white crystals of pure (l-ethyl-cyclopropyl)-glyoxylic tertiary butyl amide having a melting point of 37.5 to 29C are obtained.
c) Production of the 3-mercapto-4-amino-6-(1-ethyl-cyclopropyl)-1,2,4-triazin-5-(4H)-one 9.2 g of thiocarbohydrazide hydrochloride are put into 65 ml of H20 and mixed with 12.7 g of (l-ethyl-cyclopropyl)-gly-oxylic tertiary butyl amide in 65 ml of ethanol. The mixture is stirred for 8 hours at 80C.
At the same time a portion of the product precipitates.
The suspension is cooled to 20C, mixed with 130 ml of H20 and stirred for another hour. The precipitated crystals are filtered off and recrystallized from 50 ml of CH30H. 8 g of colorless 1C~797;~9 crystals consisting of 3-mercapt:o-4-amino-6-(1-ethyl-cyclopropyl)-1,2,4-triazin-S(4ll)-one having a melting point of 177 to 179~C
are obtained.
d) Production of the 3-methyl-thio-4~amino-6-(1-ethyl-cyclo-propyl)-1,2,4-triazin-5-(4H)-one 6 g of 3-mercapto-4-amino-6-~1-ethyl-cyclopropyl)-1,2,4-triazin-5(4~l)-one are dissolved in 14.2 ml of ~N NaOH
and 20 ml of H20 while cold. A solution consisting of 4.8 g of methyl iodide and 35 ml of CH30H is then added dropwise.
The solution is stirred for three hours at room -temp-erature, mixed wi-th H20 and then extracted three times with 50 ml of acetic ester. The organic phase is separated, dried and totally concentrated by evaporation. rrhc rcsiclue (5.7 g) is recrysta:llLzed from 70 mL oE toluane : petrolc~lm etller = 1:1 ~0 to 65C). `

4 g of white crystals having the formula:

O

/ \ /C\

C2H5 ~ D C - SC~I3 are obtained; the melting point is 93 to 95C.
Example 2 ~ .
The pre-emergent herbicidal action of the 4-amino-6-(l-ethyl-cyclo-propyl)-3-methylthio-1,2,4-triazin-5-one was determined by means of the following tests:
Herbicidal action when applying the active substances prior to the emergence of the plants (Inhibition of Germination) In a greenhouse test plants are sown in seed boxes, that is to say, culture plants as well as mono- and di-cytele-~079'729 donous weeds. Lmmediately on completing the sowing, the soilsurface was treated with an aqueous suspension of the active sub-stance obtained from a 25~ spray powder. I'hree difEerent con centration series corresponding to 0.5, 0.25 and 0.125 kg of active substance per hectare were used. The seed boxes were kept in the g~eenhouse at 22 to 25C and at a relative humidity of the air of 50 to 70~. After three weeks the test was evalu-ated and the results were rated according to the following index:

1 = plants not germinated or completely withered 2 to 8 = int.ermediate stages of damage 9 = plants undamaged (like untreated control ' plants) ___ _______ _____ Test Plant 4-amino-6-tl-ethyl-cyclo-propyl)-3-methylthio-1,2,4-tLiaz.in-5-one ..
~ ___~ _ _ g/ha 500 250 125 Avena fatua 1 1 1 Lolium perenne 1 1 1 .
Alopecurus myos. 1 1 Bromus tectorum 1 1 1 Digitaria sanguinalis 1 1 Setaria italica 1 1 1 Echninochloa crus-galli 1 1 1 Sida spinosa 1 1 1 Sesbania exaltata 1 1 1 Amarantus retroflexus 1 1 1 ..
Sinapis alba 1 1 1 Pastinaca sativa 1 1 1 Rumex sp. 1 1 1 Chrysanthemum leuc. 1 1 1 Abutilon sp. 1 1 1 Solanum nigrum 1 1 1 Soybean 3 4 107~72~

~ or the production of herbicidal agents the active sub-stance is combined with suitable fillers and/or distribution agents. This is done in a manner known per se by intimately mixing and grinding the active substance having the general formula I with suitable fillers, if required while adding dis-persing agents or solvents which are inert with respect to the active substances. The active substance can be used in the form of dusting agents, sprinkling agen-ts, granulates, sheathing gran-ulates, impregnating granulates, homogeneous granulates, wettable powders, pastes, emulsions, solutions or aerosols.
For the production of solid processing forms (dusting agents, sprlnkling agents, yranulates) the active substance is mixed with solid ~Eillers. For dustlng ~gents ~he particle size oE th~ Eillers is suitably up to appro~imately 0.1 Tnm~ Eor sprinkliny agents it is from approximately 0.075 to 0.2 mm and for granulates 0.2 mm and more. The concentrations of active substance in the solid processing forms usually is 0.5 to 80%.
Moreover, stabilizing additives and/or nonionic anionics and cationics, which, for example, improve the adhesiveness of the active substance on plants and parts thereof (adhesives) and/or assure a better wettability (wetting agents) and dispersibility ~dispersing agents) can be added to these mixtures.
Active-substance concentrates which are dispersible in water, wettable pastes and emulsion concentrates constitute agents which can be diluted with water to any concentration desired. They consist of active agent, filler, if required, additives stabilizing the active substance, surface-active sub-stances and anti-foaming agents and, if required solvents. The concentration of active substance in these agents is 5 to 80~.
The wettable powders and the pastes are obtained by mixing the active substance with dispersing agents and powdery fillers in suitable devices until the mixture is homogeneous, whereupon it ~0~97Z9 is yround. In many cases it is adva~tac3eous to use mixtures of various fillers. For cxample, silicones, etc., are suitable as anti-foaming agents. The active substance is so mixed, ground, screened and strained that the solids in wetted powders do not exceed a particle size of 0.02 to 0.04 mm and in pastes 0.003 mm. For the production of emulsion concentrates and disperslng agents, organic solvents and water are used. The solvents must ' be virtually odorless, non-phytotoxic and with respect to ~he active substance they must be inert and not easily combustible.
Furthermore, the active substance according to the invention can be applied in the form of solutions. For this purpose the active substance having -the general formula I is dlssolved in sui-table organic solvents, solvent mixtures or water. Th~ solutions should contain the active subqtance in conc~ntrations ran~ing from 1 to 20%.
Granulate For the production of a 5% granulate the following substances are used:

5 parts of active substance according to formula I, 0.25 part of epichlorohydrin, 0.25 part of cetyl polyglycol ether with 8 moles of ethylene oxide, 3.50 parts of polyglycol ("Carbowax" ~ ), 9.1 parts of kaolin (particle size 0.3 to 0.8 mm).
The active substance is mixed with epichlorohydrin and ' -dissolved with six parts of acetone, whereupon polyglycol and cetyl polyglycol ether are added. The solution thus obtained is sprayed on kaolin. The acetone is subsequently evaporated in vacuo.
~ettable Powder For the production of a) a 50~, b) a 25~ and c~ a 10%

wettable powder the following components are used: a) 50 parts _ g _ ~C)7~'7Z9 of active substance accorc~iny to foxmula 1, S parts of sodium dibutyl naphthyl sulphonate, 3 parts of naphthalene~sulphonie acids - phenol sulphonic acids - formaldehyde condensate =
3:2:1, 20 parts of kaolin, 22 parts of Champac~ne chalk; b) 25 parts of the actlve subs-tance mentioned above, 5 parts of oleyl-methyl-tauride-Ma salt, 2.5 par~s of naphtalene sulpllonie acid -formaldehyde concentra-te, 0.5 part of carboxy-methyl cellulose, 5 parts of neutral kaolin-aluminium silicate, 62 parts of kaolin;
e~ 10 parts of the above aetive substance, 3 parts of a mixture of the sodium salts of saturated fat-alcohol sulphates, 5 parts of naphthalene sulphonie aeids - formaldehyde eondensate, 82 _ parts of kaolin.
The above aetive substanee is adsorbed on the eorres-ponding fillers (kaolin and ehalk) and then mixed and c3round.
A wettable powder of exeellent wettability and suspension prop-erty is obtained. By diluting these wettable powders with water suspensions having any desired eoneentration of aetive substanee ean be obtained. These suspensions ean be used for eontrolling weeds and undesired grasses in eotton eultures.
Paste For the produetion of a 45~ paste the following sub-stanees are used: 45 parts o~ aetive substanee aeeording to formula I, 5 parts of sodium aluminlum silieate, 14 parts of cetyl polyglycol ether with 8 moles of ethylene oxide, 1 part of cetyl polyglycol ether with 5 moles of ethylene oxide, 2 parts of spindle oil, 10 parts of polyglyeol (Carbowax 23 par~s of water.
The aetive substanee is intimately mixed with the added substanees in suitable deviees and ground. A paste from whieh suspensions having any desired eoneentration ean be pro-duced by dilution with water is obtained.

,.."," ,' . ' ~0~797Z9 Emulsion Concentrate .
For the production of a 10~ emulsion concentrate 10 parts of active substance according to formula I, 15 par-ts of cetyl polyglycol ether with 8 moles of ethylene oxide and 75 parts of isophorone ~3,5,5-trimethyl-cyclohex-2-en-1-one) are intimately mixed. This concentrate can be dlluted with water to suitable concentrations. These emulsions are suitable for the control of weeds in cultivated plants, as for example, soy-beans and potatoes, etc.

Claims (6)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A 1,2,4-triazin-5-one-derivative having the gen-eral formula

2. A process for producing a 1,2,4-triazin-5-one derivative which comprises condensing a compound having the formula H2N ? NH ? CS ? NH ? NH2 with a (1-ethyl-cyclopropyl)-glyoxylic acid-tert.-alkyl amide in an acid medium and methylating the reaction product.

3. A method of controlling weeds which comprises applying thereto a compound as claimed in claim 1.

4. A method as claimed in claim 3 in which the weeds are mono- or di-cyteledonous weeds.

5. A method as claimed in claim 3 in which the weeds are Gramineae.

6. A method as claimed in claim 3, 4 or 5 in which the application is post-emergent.