GB2063855A - Triazolidine derivatives and process for preparing the same - Google Patents

Abstract

1,2,4-Trisubstituted-triazolidin-3- one-5-thiones represented by the general formula: <IMAGE> wherein R<1> is C1-3 alkyl, R<2> is C1-3 alkyl, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, C1-4 alkyl, C1-4 alkoxy, nitro and haloalkyl of 1 to 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, and R<4> is C1-6 alkyl phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, C1-4alkyl, C1-4 alkoxy, nitro and haloalkyl of 1 or 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, are prepared by the reaction of an appropriately 1,2,4- trisubstituted semicarbazide and thiophosgene in the liquid phase in an inert diluent and in the presence of a base. The triazolidine derivatives are useful as herbicides and plant-growth- regulators.

Description

SPECIFICATION Triazolidine derivatives and process for preparing the same This invention relates to 1, 2, 4-trisubstituted triazolidine derivatives having herbicidal and plant-growth regulating properties.

The compounds of the invention are 1, 2, 4-triazoiidin-3-one-5-thiones represented by the general formula:

wherein R1 is alkyl of from 1 to 6 carbon atoms, R2 is alkyl of from 1 to 6 carbon atoms, phenyl, or phenyi substituted by 1 or 2 of the same of different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 or 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, and R4 is alkyl of from 1 to 6 carbon atoms, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 or 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo.

Representative alkyl R1, R2 and R4 groups are methyl, ethyl and propyl.

Representative substituted phenyl R2 and R4 groups include 2-fluorophenyl, 2-chlorophenyl, 3bromophenyl, 2,4-diidophenyl, 4-chloromethylphenyl, 3-trichloromethylphenyl, 4-methoxyphenyl, 3nitrophenyl and 3,5-dinitrophenyl.

Preferably R' and R2 are alkyl of 1 to 3 carbon atoms, especially methyl.

Preferably R4 is phenyl substituted by 1 or 2 fluoro, chloro, bromo or iodo. Most preferably R4 is phenyl substituted by 1 or 2 fluoro or chloro.

The compounds of the invention may be prepared by reacting a semicarbazide (II) and thiophosgene (III) in accordance with the following reaction (1):

wherein R1, R2 and R4 have the same significance as in formula Reaction (1) is conducted by reacting the semicarbazide (II) and thiophosgene (III) in the liquid phase in an inert diluent. Generally, the molar ratios of semicarbazide to thiophosgene vary from about 1.2:1 to 1:1.2, although molar ratios of from about 1.1:1 to 1:1.1 are preferred. Reaction (1) is conducted in the presence of a base to scavenge the hydrogen chloride produced in the reaction. Generally, the molar ratios of base to thiophosgene vary from about 2.2:1 to 2:1. Suitable bases include organic nitrogen bases such as trialkylamines, e.g., triethylamine and tributylamine, and pyridine compounds, e.g. pyridine and 2-methylpyridine.Inorganic bases such as alkali metal carbonates and bicarbonates, e.g., sodium carbonate and potassium bicarbonate, can also be used.

The reaction is conducted in inert organic diluents, e.g., haloalkanes such as dichloromethane and chloroform, aromatic compounds such as benzene, toluene and chlorobenzene, and ethers such as dimethoxyethane, tetrahydrofuran and dioxane. Reaction temperatures vary from about 0 to 1 500C, although temperatures of from about 20"C to 100"C are preferred. The reaction pressure can be atmospheric, subatmospheric or superatmospheric. However, for convenience of conducting the reaction, the pressure is generally atmospheric. The reaction time will, of course, vary depending upon the particular reactants and the reaction temperature. Generally, the reaction time is from several minutes to 24 hours.The product (I) is generally isolated and purified by conventional procedures, e.g., extraction, chromatography, crystallization, etc.

EXAMPLES Example 1-- Preparation of l,2-dimethyl-4-phenyl- l,2,4-triazolldine-3-one-5-thione A solution of 4.26 g (0.037 mol) thiophosgene in about 10 ml chloroform was added dropwise to a solution of 6.7 g (0.037 mol) 1,2-dimethyl-4-phenylsemicarbazide and 7.47 g (0.074 mol) triethylamine in 200 ml chloroform. A slightly exothermic reaction ensued. One hour after the addition was completed, the reaction mixture was heated under reflux for about 16 hours, cooled and evaporated under reduced pressure to give an oil residue. The residue was dissolved in dichloromethane, washed with water, dried over magnesium sulfate, filtered and evaporated under reduced pressure to give a red viscous oil. The oil was chromatographed on 200 g of silica gel using dichloromethane as eluant.The major product (4 g) from the chromotography was a semisolid, which on trituration with ether gave the desired product as a light tan solid, m.p. 1 18-122"C. Infrared spectrum of the product showed strong carbonyl absorption at 5.8 micron.

The product is tabulated in Table I as Compound No. 1.

Example 2 -- Preparation of l,2-dimethyl-4-(4-chlorophen yl)- 1,2,4-triazolidin-3-one-5-thione A solution of 3.8 g (0.033 mol) thiophosgene in 10 ml chloroform was added dropwise to a stirred solution of 7 g (0.033 mol) 1,2-dimethyl-4-(4-chlorophenyl)semicarbazide and 6.67 g (0.066 mol) triethylamine in 200 ml chloroform. After completion of the addition, the reaction mixture was headed under reflux for 2 hours and stirred at about 25"C for 3 days. The reaction mixture was then washed with water, dilute hydrochloric acid solution, dried over magnesium sulfate, filtered and evaporated under reduced pressure to give 10 g of a semi-solid residue. The residue was diluted with 100 ml dichloromethane and filtered. The filtrate was chromatographed on 200 g of silica gel.Elution with 1% methanol in dichloromethane gave the product, 3.9 gaslight tan crystals, m.p. 143-144"C. Infrared analysis showed strong carbonyl absorption at 5.8 micron.

The product is tabulated in Table I as Compound No. 2.

The compounds tabulated in Table I were prepared by procedures similar two those of Examples 1-2. The structure of each compound tabulated in Table I was confirmed by nuclear magnetic resonance and/or infrared spectroscopy.

Utility The compounds of the present invention are, in general, herbicidal in both pre- and post-emergent applications. For pre-emergent control of undesirable vegetation, the herbicidal compounds will be applied in herbicidally effective amounts to the locus or growth medium of the vegetation, e.g., soil infested with seeds and/or seedlings of such vegetation. Such application will inhibit the growth of or kill the seeds, germinating seeds and seedlings. For post-emergent applications, the herbicidal compounds will be applied directly to the foliage and other plant parts. Generally, the herbicidal compounds of the invention are effective against weed grasses as well as broad-leaved weeds. Some may be selective with respect to the type of application and/or type of weed. The compounds are particularly effective as pre-emergent herbicides against weed grasses.

The compounds, when applied to growing plants above the ground in such an amount that the compounds will not kill beneficial plants, also show efficient plant growth regulating or retarding effects and may be advantageously employed, for example, to prevent or retard the growth of lateral buds in plants and to promote the thinning out of superfluous fruits in various fruit trees.

The compounds can be applied in any of a variety of compositions. In general, the compounds can be extended with a carrier material of the kind used and commonly referred to in the art such as inert solids, water and organic liquids.

The compounds will be included in such compositions in sufficient amount so that they can exert a herbicidal or growth-regulating effect. Usually from about 0.5 to 95% by weight of the compounds are included in such formulations.

Solid compositions can be made with inert powders. The compositions thus can be homogeneous powders that can be used as such, diluted with inert solids to form dusts, or suspended in a suitable liquid medium for spray application. The powders usually comprise the active ingredient admixed with minor amounts of conditioning agent. Natural clays, either absorptive, such as attapulgite, or relatively non-absorptive, such as china clays, diatomaceous earth, synthetic fine silica, calcium silicate and other inert solid carriers of the kind conventionally employed in powdered herbicidal compositions can be used. The active ingredient usually makes up from 0.5-90% of these powder compositions. The solids ordinarily should be very finely divided. For conversion of the powders to dusts, talc, pyrophyllite, and the like, are customarily used.

Liquid compositions including the active compounds described above can be prepared by admixing the compound with a suitable liquid diluent medium. Typical of the liquid media commonly employed are methanol, benzene, toluene, and the like. The active ingredient usually makes up from about 0.5 to 50% of these liquid compositions. Some of these compositions are designated to be used as such, and others to be extended with large quantities of water.

Compositions in the form of wettable powders or liquids can also include one or more surface-active agents, such as wetting, dispersing or emulsifying agents. The surface-active agents cause the compositions of wettable powders or liquids to disperse or emulsify easily in water to give aqueous sprays.

The surface-active agents employed can be of the anionic, cationic or nonionic type. They include, for example, sodium long-chain carboxylates, alkyl aryl sulfonates, sodium lauryl sulfate, polyethylene oxides, lignin sulfonates and other surface-active agents.

When used as a pre-emergent treatment, it is desirable to include a fertilizer, an insecticide, a fungicide or another herbicide.

The amount of compound or composition administered will vary with the particular plant part of plant growth medium which is to be contacted, the general location of application --i.e., sheltered areas such as greenhouses, as compared to exposed areas such as fields-- as well as the desired type of control. Generally for both pre- and post-emergent herbicidal control, the compounds of the invention are applied at rates of 0.2 to 60 kg/ha, and the preferred rate is in the range of 0.5 to 40 kg/ha. For plant growth regulating or retarding activity, it is essential to apply the triazolidine compounds at a concentration not so high as to kill the plants. Therefore, the application rates for plant growth regulating or retarding activity will generally be lower than the rates used for kiiling the plants.Generally, such rates vary from 0.1 to 5 kg/ha, and preferably from 0.1 to 3 kg/ha.

Herbicidal and plant-growth-regulating tests on representative compounds of the invention were made using the following methods.

Pre-emergent herbicidal test An acetone solution of the test compound was prepared by mixing 375 mg of the compound, 118 mg of a nonionic surfactant and 18 ml of acetone. 10 ml of this solution was added to 40 ml of water to give the test solution.

Seeds of the test vegetation were planted in a pot of soil and the test solution was sprayed uniformly onto the soil surface at a dose of 27.5 micrograms/cm2. The pot was watered and placed in a greenhouse. The pot was watered intermittently and observed for seedling emergence, health of emerging seedlings, etc., for a 3-week period. At the end of this period, the herbicidal effectiveness of the compound was rated on the physiological observations. A 0-to-100 scale was used, 0 representing no phytotoxicity, 100 representing complete kill. The results of these tests appear in Table II.

Post-emergent herbicidal test The test compound was formulated in the same manner as described above for the pre-emergent test.

This formulation was uniformly sprayed on 2 similar pots of 24-day-old plants (approximately 15 to 25 plants per pot) at a dose of 27.5 microgram/cm2. After the plants had dried, they were placed in a greenhouse and then watered intermittently at their bases, as needed. The plants were observed periodically for phytotoxic effects and physiological and morphological responses to the treatment. After 3 weeks, the herbicidal effectiveness of the compound was rated based on these observations. A 0-to-i 00 scale was used, 0 representing no phytotoxicity and 100 representing complete kill. The results of these tests appear in Table II.

Axillary bud growth inhibition ofpinto bean plants Compound No. 2 was tested to determine its plant-growth-retarding effects on axiliary bud growth of pinto beans.

Idaho pinto bean plants (13-16 days old) having mono-foliate leaves fully developed and first trifoliates beginning to unfold were used. All growth 5 mm above the monofoiiate leaf node was removed with forceps 1 to 4 hours prior to treatment with the test compounds. Four plants were used for each test compound.

A 625-ppm solution of the test compound in a 2% aqueous acetone solution containing a small amount of a non-ionic surfactant was sprayed onto the pinto bean plants until runoff. After drying, the treated plants were transferred to a greenhouse maintained at 20-230C and watered at regular intervals. Twelve days after treatment, the bud growth at the axil of the monofoliate leaf was determined and expressed as percent inhibition of axillary bud growth as compared to untreated check plants. The percent inhibition for Compound No. 2 was 85%.

Cotton defoliation test Compound No. 2 was tested to determine its post-emergent foliar activity for cotton defoliation and/or desication.

Cotton plants (26-35 days old) with 4 fully expanded leaves were used. Two days before use, the growth beyond the 4th leaf was removed.

A 5000-ppm solution of the test compound in acetone containing a small amount of a nonionic surfactant was sprayed on two cotton plants until run off. The treated plants were transferred to a greenhouse maintained at 23-25"C. The plants were watered from the base 1-2 times per day using an automatic sub-irrigation system. Ten days after treatment the percent defoliation and desiccation was determined (relative to the original number of mature leaves). The results for Compound No. 2 were 75% defoliation and 18% desiccation.

TABLE I Compounds of the formula

Elemental Analysis No. R4 m.p., "C Calculated Found 1 * 118-122 S 14.3 S 14.1 2 4-CI-0 139-142 S 12.5 S 12.3 Cl 13.9 Cl 12.9 3 3,4-C12-pl 165-167 S 11.0 S 11.6 Cl 24.5 Cl 22.7 4 3-CF3-0 107-109 C 45.7 C 46.3 H 3.5 H 3.6 N 14.5 N 14.9 5 4-F-0 178-180 C 50.2 C 50.8 H 4.2 H 4.4 N 17.6 N 17.9 6 3-CF3-4-CI-pr 157-159 C 40.7 C 40.4 H 2.8 H 2.8 N 13.0 N 13.8 * represents phenyl TABLE II -- Herbicidal Effectiveness % Control - Pre/Post No. L M P C W O 1 80/45 60/0 50/0 20/0 30/0 35/0 2 100/85 100/70 100/88 100/20 95/50 95/20 3 100/78 98/35 100/20 95/20 90/20 80/0 4 20/20 20/30 20/20 0/0 0/0 0/0 5 90/35 90/20 93/40 85/0 95/0 90/0 6 90/0 85/0 85/0 85/0 75/0 65/0 L = Lambsquarter (Chenopodium album) M = Mustard (Brassica arvensis) P = Pigweed (Amaranthus retroflexus) C = Crabgrass (Digitaria sanguinalis) W = Watergrass (Echinochloa crusgalli) O = Wild Oats (Avenua fatua)

Claims (13)

1. Triazolidin-3-one-5-thiones represented by the general formula:

wherein R1 is alkyl of from 1 to 3 carbon atoms, R2 is alkyl of from 1 to 3 carbon atoms, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 or 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, and R4 is alkyl of from 1 to 6 carbon atoms, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 or 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo.

2. Compounds as claimed in Claim 1, wherein R1 and R2 are each alkyl of from 1 to 3 carbon atoms.

3. Compounds as claimed in Claim 1 or 2, wherein R4 is phenyl substituted by 1 or 2 fluoro, chloro, bromo or iodo.

4. Compounds as claimed in Claim 1, wherein R1 and R2 are methyl and R4 is phenyl substituted by 1 or 2 fiuoro or chloro.

5. 1 ,2-Dimethyl-4-(4-ch lorophenyl)-1 ,2,4-triazolidin-3-one-5-thione.

6. A process for preparing a compound as claimed in Claim 1, which comprises reacting a semicarbazide of the general formula:

wherein R1, R2 and R4 have the same meanings as in Claim 1, with thiophosgene in the liquid phase in an inert diluent and in the presence of a base to form the required compound.

7. A process according to Claim 6, wherein the semicarbazide and thiophosgene are reacted in molar ratios of from 1.1:1 to 1:1.1.

8. A process according to Claim 6, substantially as described in either of the foregoing Examples.

9. A herbicidal composition comprising a biologically inert carrier and a herbicidally effective amount of a compound as claimed in any one of Claims 1 to 5.

10. A plant-growth-regulating composition comprising a biologically inert carrier and a plant-growthregulating amount of a compound as claimed in any one of Claims 1 to 5.

11. A method of controlling undesirable vegetation, which comprises applying to said vegetation or its growth medium a herbicidally effective amount of a compound as claimed in any one of claims 1 to 5.

12. A method of regulating plant growth, which comprises applying to said plant or its growth environment a plant-growth-retarding amount of a compound as claimed in any one of Claims 1 to 5.

New claims or amendments to claims filed on 4.11.80 New or amended claims:

13. Triazolidin-3-one-5-thiones represented by the general formula:

wherein R1 is alkyl of from 1 to 3 carbon atoms, R2 is alkyl of from 1 to 3 carbon atoms, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 to 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, and R4 is alkyl of from 1 to 6 carbon atoms, phenyl or phenyl substituted by 1 or 2 of the same or different substituents selected from fluoro, chloro, bromo, iodo, alkyl of 1 to 4 carbon atoms, alkoxy of 1 to 4 carbon atoms, nitro and haloalkyl of 1 to 2 carbon atoms and 1 to 3 fluoro, chloro, bromo or iodo, with the proviso that R4 is not 3,5-dihalophenyl.