Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D231/00—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings
  • C07D231/02—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings
  • C07D231/10—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
  • C07D231/14—Heterocyclic compounds containing 1,2-diazole or hydrogenated 1,2-diazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
  • C07D231/16—Halogen atoms or nitro radicals
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/12—Powders or granules
  • A01N25/14—Powders or granules wettable
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N43/00—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds
  • A01N43/72—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with nitrogen atoms and oxygen or sulfur atoms as ring hetero atoms
  • A01N43/80—Biocides, pest repellants or attractants, or plant growth regulators containing heterocyclic compounds having rings with nitrogen atoms and oxygen or sulfur atoms as ring hetero atoms five-membered rings with one nitrogen atom and either one oxygen atom or one sulfur atom in positions 1,2
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01P—BIOCIDAL, PEST REPELLANT, PEST ATTRACTANT OR PLANT GROWTH REGULATORY ACTIVITY OF CHEMICAL COMPOUNDS OR PREPARATIONS
  • A01P13/00—Herbicides; Algicides
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D413/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms
  • C07D413/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms containing two hetero rings
  • C07D413/12—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms containing two hetero rings linked by a chain containing hetero atoms as chain links

Definitions

• the present invention relates to a novel intermediate of the formula (I) or its salt, which is a valuable intermediate in synthesis of Pyroxasulfone and process for preparation of the same.
• the present invention further relates to a process for preparation of Pyroxasulfone using this novel intermediate of formula (I) or its salt.
• Pyroxasulfone is a herbicide belonging to the group of pyrazolium. Pyroxasulfone is chemically known as 3-[5-(difluoromethoxy)-l-methyl-3- (trifluoromethyl)pyrazol-4-ylmethylsulfonyl]-4,5-dihydro-5, 5-dimethyl- 1,2- oxazole and represented by compound of formula (VII).
• Pyroxasulfone was first disclosed in US patent No. 7, 238, 689. Currently, few processes for preparation of Pyroxasulfone are known. The method for preparation of Pyroxasulfone known in the prior art are lengthy, tedious and possess problems in the scale-up to commercial production. Another issue involved is availability of the starting material used. These problems have necessitated further research in an attempt to discover a shorter route which involves use of easily available materials for preparation of Pyroxasulfone.
• Another object of the present invention is to provide a process for preparation of a compound of formula (I) or its salt.
• Yet another object of the present invention is to provide an alternative synthesis route for preparation of Pyroxasulfone using compound of formula (I) or its salt.
• Yet another object of the present invention is to provide an alternative synthesis route for preparation of compound of formula (IV), an advance intermediate formed in Pyroxasulfone preparation.
• Formula (II) Formula (I) wherein R is selected from halogen or hydroxy group, with thiourea to obtain compound of formula (I) or its salt; b) condensing compound of formula (I) or its salt with isooxazoline compound of formula (III) to get compound of formula (IV),
• a process for purification of Pyroxasulfone comprising treating the crude Pyroxasulfone with mixture of alcohol and water at temperature ranging from 50 to 110°C.
• Pyroxasulfone is characterized by having D50 particle size value of less than about 200pm, preferably less than about 150mih.
• Pyroxasulfone having bulk density of about 0.40 g/cc to 0.90 g/cc.
• the present invention provides an agrochemical composition comprising Pyroxasulfone prepared according to the present process. In another aspect the present invention provides an agrochemical composition comprising Pyroxasulfone prepared using the compound of formula (I).
• composition comprising Pyroxasulfone characterized by an X-ray powder diffraction pattern exhibiting at least three peaks selected from 9.90°, 17.72°, 17.94°, 19.91°, 20.36°, 20.60°, 21.76°, 22.09°, 22.31°, 22.70°, 25.10°, 25.41°, 26.57°, 27.01°, 28.40°, and 30.18° ⁇ 0.2° 2Q.
• X-ray powder diffraction pattern exhibiting at least three peaks selected from 9.90°, 17.72°, 17.94°, 19.91°, 20.36°, 20.60°, 21.76°, 22.09°, 22.31°, 22.70°, 25.10°, 25.41°, 26.57°, 27.01°, 28.40°, and 30.18° ⁇ 0.2° 2Q.
• Fig. 1 illustrates powder X-ray diffraction (PXRD) pattern of Pyroxasulfone prepared according to example 10.
• “About” or “approximately” as used herein is inclusive of the stated value and means within an acceptable range of deviation for the particular value as determined by one of ordinary skill in the art, considering the measurement in question and the error associated with measurement of the particular quantity (i.e., the limitations of the measurement system). For example, “about” can mean within one or more standard deviations, or within ⁇ 10% or ⁇ 5% of the stated value. Recitation of ranges of values are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. The endpoints of all ranges are included within the range and independently combinable.
• alkyl refers to a straight or branched chain saturated aliphatic hydrocarbon having the specified number of carbon atoms, specifically 1 to 12 carbon atoms, more specifically 1 to 8 carbon atoms.
• halogen refers to a fluorine, chlorine, bromine, or iodine atom.
• room temperature unless stated otherwise, essentially means temperature in range of 20-45 °C.
• purity means purity as determined by HPLC ("High Pressure Liquid Chromatography").
• Pyroxasulfone or “compound of formula (VII)” as used herein, includes Pyroxasulfone free base or its salts or its crystalline forms and polymorphs and is used interchangeably throughout the disclosure.
• a compound of formula (la) or its salt wherein A is hydrogen, -C(NH)(NH2) or alkali metal.
• the salt of compound of formula (I) can be its hydrochloride salt or hydrobromide salt.
• the salt of compound of formula (I) is its hydrochloride salt.
• Formula (II) Formula (I) wherein R is selected from halogen or hydroxy group.
• R is chlorine. According to an embodiment, R is a hydroxy group.
• the amount of thiourea used is in the range of 1 to 1.5 moles with respect to the compound of formula (II).
• the compound of formula (II) is condensed with thiourea in presence of an organic solvent at temperature ranging from 0°C to 150°C.
• the organic solvent used is selected from lower alcohol such as methanol, ethanol, isopropanol, n-propanol, butanol, tert-butanol and the like, hydrocarbons such as toluene, xylene, benzene and like, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform and the like, ethers such as methyl tert-butyl ether, tetrahydrofuran, dioxane and the like.
• the amount of organic solvent used is in the range of 1 to 60 moles with respect to compound of formula (II).
• the compound of formula (II) is condensed with thiourea in presence of an organic or inorganic acid.
• the organic acid used is selected from acetic acid, formic acid, oxalic acid, and the likes.
• the inorganic acid used is selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, hydrofluoric acid, hydrobromic acid, perchloric acid, hydroiodic acid.
• the amount of acid used may vary from catalytic amount to 6 equivalents with respect to compound of formula (II).
• the compound of formula (II) is condensed with thiourea at temperature ranging from 0°C to 150°C for 0.5 to 20 hours.
• the compound of formula (I) is isolated by the methods known in prior art for example by filtration, crystallisation, distillation, extraction and the likes.
• the compound of formula (I) obtained is filtered and washed with a non-polar solvent such as hexane, heptane, petroleum ether or mixture thereof.
• the compound of formula (I) is in salt form, preferably it is hydrochloride salt. According to an embodiment, there is provided a process for the preparation of the compound of formula (I) or its salt, comprising condensing compound of formula (Ila) with thiourea.
• a process for preparation of Pyroxasulfone of formula (VII) comprising the steps of: a) condensing compound of formula (II) with thiourea to obtain compound of formula (I) or its salt;
• Formula (II) Formula (I) wherein R is selected from halogen or hydroxy group and b) converting compound of formula (I) or its salt to Pyroxasulfone of formula
• the process of converting compound of formula (I) or its salt to Pyroxasulfone of formula (VII) comprising the steps of; a) condensing compound of formula (I) or its salt with isooxazoline compound of formula (III) to get compound of formula (IV),
• Formula (V) Formula (VI) d) oxidising compound of formula (VI) to get Pyroxasulfone of formula (VII).
• a process for preparation of Pyroxasulfone wherein the process proceeds via the intermediate of formula (I).
• a process for preparation of Pyroxasulfone wherein the process proceeds via the intermediate of formula (la).
• a process for preparation of Pyroxasulfone wherein the process proceeds via the intermediate of formula (IV).
• Formula (V) Formula (VI) e) oxidising compound of formula (VI) to get Pyroxasulfone of formula (VII).
• the step a) of the process is carried out in presence of an organic solvent at temperature ranging from 0°C to 150°C.
• the organic solvent used is selected from lower alcohol such as methanol, ethanol, isopropanol, n-propanol, butanol, tert-butanol and the like, hydrocarbons such as toluene, xylene, benzene and like, halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform and the like, ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone and the likes, ethers such as methyl tert-butyl ether, tetrahydrofuran, dioxane and the like.
• the step a) is carried out in presence of an organic or inorganic acid.
• the step b) of the process comprises condensing compound of formula (I) or its salt with isooxazoline compound of formula (III) and said step is carried out in presence of a base like carbonates selected from potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate and the like, hydroxides selected from potassium hydroxide, sodium hydroxide, ammonium hydroxide and the like, or alkoxides like sodium alkoxide or potassium alkoxide.
• a base like carbonates selected from potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate and the like
• hydroxides selected from potassium hydroxide, sodium hydroxide, ammonium hydroxide and the like
• alkoxides like sodium alkoxide or potassium alkoxide.
• the amount of base used is in the range of 0.5 to 3 moles with respect to compound of formula (I).
• the step b) is carried out in presence of a polar solvent such as alcohols like methanol, ethanol, isopropanol, n-propanol, tert-butanol and the like, ethers such as tetrahydrofuran, 1,6-dioxane and the like, water, dimethylformamide or mixture thereof.
• a polar solvent such as alcohols like methanol, ethanol, isopropanol, n-propanol, tert-butanol and the like, ethers such as tetrahydrofuran, 1,6-dioxane and the like, water, dimethylformamide or mixture thereof.
• an alcohol, water, or a mixture thereof is used as solvent.
• the step b) is carried out at temperature ranging from 0°C to 150°C.
• the step c) of the process comprises converting compound of formula (IV) to compound of formula (V) wherein the compound of formula (IV) is first converted to compound of formula (Va) followed by converting compound of formula (Va) to compound of formula (V).
• the compound of formula (IV) is alkoxylated using an alkoxylating agent in presence of an alcohol to obtain compound of formula (Va); followed by treatment with an acid to obtain compound of formula (V).
• compound of formula (IV) is alkoxylated using alkoxylating agent such as sodium methoxide, sodium ethoxide and so on, in presence of an alcohol such as methanol to obtain a compound of formula (Va).
• alkoxylating agent such as sodium methoxide, sodium ethoxide and so on
• the compound of formula (Va) obtained is converted to compound of formula (V) by treatment with an acid selected from organic or inorganic acid or mixture thereof.
• the organic acid used is selected from acetic acid, formic acid, oxalic acid, and the likes.
• the inorganic acid used is selected from hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, hydrofluoric acid, hydrobromic acid, perchloric acid, hydroiodic acid or Lewis acids such as boron tribromide, boron trichloride, boron trifluoride.
• hydrobromic acid in acetic acid used for converting formula (Va) to compound of formula (V).
• the compound of formula (Va) obtained is converted to compound of formula (V) by treatment with an acid in presence of a suitable solvent.
• the suitable solvent used may be selected from water, an organic solvent such as chlorinated solvent like dichloromethane, dichloroethane, chloroform and the likes, ethers such as diethyl ether, tetrahydrofuran and the likes, hydrocarbons such as toluene, xylene and the like, or mixtures thereof.
• the step c) is carried out at temperature ranging from 0°C to 100°C.
• One of the advantages of the present invention is preparation of compound of formula (V) using a simple reaction.
• compound of formula (IV) is alkoxylated to compound of formula (Va) which is then treated with acid to get compound of formula (V).
• the step d) of the process comprises fluoromethylating compound of formula (V) to get compound of formula (VI), wherein step d) is carried out in presence of fluoromethylating agent such as difluorochloromethane (Freon gas) in presence of an alkaline reagent and an organic solvent.
• fluoromethylating agent such as difluorochloromethane (Freon gas)
• the amount of freon gas used is in the range of 3 to 10 moles with respect to the compound of formula (V).
• the alkaline reagent used can be inorganic base and/or organic base, the inorganic base is preferably one or more of potassium carbonate, sodium carbonate, potassium bicarbonate, sodium bicarbonate, potassium hydroxide and sodium hydroxide, and the organic base is preferably one or more of triethylamine, pyridine, triethylene diamine and N, N-dimethyl pyridine.
• the amount of alkaline reagent used is in the range of 1.5 to 7 moles with respect to compound of formula (V).
• the organic solvent used may be selected from one or more of acetonitrile, N, N- dimethylformamide, tetrahydrofuran, methanol, ethanol, isopropanol, and the like.
• the amount of organic solvent used is in the range of 30 to 90 moles with respect to compound of formula (V).
• the step d) is carried out at temperature ranging from 0°C to 50°C.
• the step e) of the process comprises oxidising compound of formula (VI) to get Pyroxasulfone of formula (VII) wherein oxidation is carried out in presence of an oxidizing agent.
• the oxidizing agent used may be selected from organic peroxides such as m- chloroperbenzoic acid, performic acid, peracetic acid and the like; inorganic peroxides such as hydrogen peroxide, potassium permanganate, sodium periodate or oxone® (Potassium peroxymonosulfate) and the like.
• organic peroxides such as m- chloroperbenzoic acid, performic acid, peracetic acid and the like
• inorganic peroxides such as hydrogen peroxide, potassium permanganate, sodium periodate or oxone® (Potassium peroxymonosulfate) and the like.
• the amount of oxidizing agent used is 1 to 4 moles with respect to compound of formula (VI).
• the step e) oxidation is carried out in presence of an oxidizing agent in an organic solvent to obtain the Pyroxasulfone of formula (VII).
• the step e) oxidation is carried out in presence of a metal catalyst.
• the catalyst used can be a metal catalyst such as tungsten catalyst, molybdenum catalyst, titanium catalyst, zirconium catalyst or mixture thereof
• the tungsten catalyst used may be selected from tungsten, tungstic acid, tungstic acid salt, metallic tungsten, tungsten oxide, tungsten carbide or mixtures thereof.
• the tungsten catalyst such as tungsten chloride, tungsten bromide, tungsten sulfide, phospho tungstic acid or a salt thereof, tungstic acid or a salt thereof, sodium tungstate, potassium tungstate, calcium tungstate, lithium tungstate, tungsten tungstate, coordination complex of tungsten or mixture thereof, may be used.
• the tungsten catalyst used is sodium tungstate, more preferably sodium tungstate dihydrate is used.
• the molybdenum catalyst used may be selected from molybdic acid, molybdates, metallic molybdenum, molybdenum carbide, molybdenum oxide, molybdenum chloride or mixtures thereof.
• the molybdenum catalyst such as molybdate, sodium molybdate, potassium molybdate, ammonium molybdate, molybdate oxide (VI), molybdenum carbide, molybdenum chloride (V), molybdate sulfide (IV), phosphomolybdate, sodium phosphomolybdate, ammonium phosphomolybdate, silicate molybdate or mixtures thereof, coordination complex of molybdenum may be used.
• the molybdenum catalyst used is ammonium molybdate, more preferably ammonium molybdate tetrahydrate is used.
• the titanium catalyst used may be selected from titanic acid, titanate, titanium oxide, titanium carbide, titanium chloride and mixtures thereof.
• the zirconium catalyst used may be selected from zirconium oxide, zirconium carbide, zirconium chloride and mixtures thereof.
• the oxidation step is carried out in presence of oxidising agent and a metal catalyst.
• the oxidation step is carried out in presence of hydrogen peroxide as an oxidising agent and sodium tungstate dihydrate as a metal catalyst.
• the step e) oxidation is carried out in presence of a metal catalyst and an acid.
• the acid used is an inorganic acid or organic acid.
• the inorganic acid like sulfuric acid, hydrochloric acid, or an organic acid such as acetic acid and formic acid.
• the step e) oxidation is carried out in presence of a suitable solvent selected from group comprising of halogenated hydrocarbon; ethers; amides; alcohols; ketones; nitriles; carboxylic acids; water or mixtures thereof.
• a suitable solvent selected from group comprising of halogenated hydrocarbon; ethers; amides; alcohols; ketones; nitriles; carboxylic acids; water or mixtures thereof.
• the organic solvent used may be selected from halogenated hydrocarbon such as dichloromethane, chloroform, dichloroethane, carbon tetrachloride, chlorobenzene, dichlorobenzene and the like; ethers such as dioxane, tetrahydrofuran (THF), dimethoxyethane, diethyl ether and the like; amides such as N,N- dimethylacetamide, N,N-dimethylformamide, N-methyl-2-pyrrolidinone and the like; alcohols such as methanol, ethanol, propanol, isopropanol, butanol, tert- butanol and the like; ketones such as acetone, 2-butanone and the like: nitriles such as acetonitrile and the like acetic acid; water, and mixtures thereof.
• halogenated hydrocarbon such as dichloromethane, chloroform, dichloroethane, carbon tet
• the oxidation is carried out in presence of potassium peroxymonosulfate as an oxidising agent.
• a process for preparation of Pyroxasulfone of formula (VII), comprising oxidising compound of formula (VI) using potassium peroxymonosulfate as oxidising agent
• pyroxasulfone thus obtained can be further treated with aqueous base and subjected to purification by treating pyroxasulfone with alcohol or aqueous alcohol.
• the base used may be selected from alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and the like.
• the alcohol used may be selected from methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol and the like.
• the purification of crude Pyroxasulfone comprises washing of the crude Pyroxasulfone with alcohol.
• the purification of crude Pyroxasulfone by treatment with mixture of alcohol and water is carried out at temperature ranging from 50 to 110°C.
• the step of purification of crude Pyroxasulfone further comprises cooling of reaction mixture to room temperature to isolate purified Pyroxasulfone after treatment with mixture of alcohol and water at higher temperature.
• a process for preparation of Pyroxasulfone of formula (VII) comprising a) condensing compound of formula (Ila)
• Formula (V) Formula (VI) e) oxidising compound of formula (VI) to get Pyroxasulfone of formula (VII).
• Formula (lib) Formula (I) with thiourea to obtain compound of formula (I) or its salt; b) condensing compound of formula (I) or its salt with isooxazoline compound of formula (Ilia) to get compound of formula (IV),
• Formula (V) Formula (VI) e) oxidising compound of formula (VI) to get Pyroxasulfone of formula (VII).
• a process for purification of crude Pyroxasulfone comprising treating the crude Pyroxasulfone with mixture of alcohol and water at temperature ranging from 50°C to 110°C.
• a process for purification of crude Pyroxasulfone comprising treating the crude Pyroxasulfone with mixture of isopropyl alcohol and water at temperature ranging from 60°C to 100°C.
• a process for preparation of compound of formula (IV) comprising condensing novel compound of formula (la) or its salt with isooxazoline compound of formula (Ilia) to get compound of formula (IV), wherein A is hydrogen, -C(NH)(NH2) or alkali metal, and L is a leaving group.
• the compound of formula (la) wherein A is hydrogen, -C(NH)(NH2) or alkali metal for example sodium, potassium, lithium etc, can be used.
• the compound of formula (Ilia) wherein L is a leaving group such as halogen, -SO2R 1 wherein R 1 is lower alkyl group can be used.
• Pyroxasulfone characterized by having D50 particle size value of less than about 200pm, preferably less than about 150mih.
• the agrochemical composition comprising pyroxasulfone prepared according to the present process as described herein.
• the present invention provides a herbicidal composition
• a herbicidal composition comprising pyroxasulfone prepared according to the process as described herein and at least one agrochemically acceptable excipients.
• the present herbicide composition further comprising additional herbicide.
• the additional herbicide is triazinone herbicide.
• the herbicidal composition comprising a combination of pyroxasulfone prepared according to the present process and a triazinone herbicide.
• the triazinone herbicide is selected from the group of ametridione, amibuzin, ethiozin, hexazinone, isomethiozin, metamitron, metribuzin, or trifludimoxazin. In an embodiment, the triazinone herbicide is metribuzin.
• the present invention provides herbicidal composition comprising combination of pyroxasulfone prepared according to present process and metribuzin.
• the herbicide composition comprising pyroxasulfone prepared according to process as described herein; and at least one agriculturally acceptable excipient.
• agriculturally acceptable excipient/ carriers can be selected from one or more diluents, emulsifiers, fillers, anti-foaming agents, thickening agents, anti-freezing agents, freezing agents, a surfactant, a preservative, a coloring agent, a pH adjusting agent, dispersing agent, wetting agent and solvent.
• any other agriculturally acceptable excipients as known to a person skilled in the art, may be used to serve its intended purpose.
• the agriculturally acceptable excipients are present in an amount ranging from 0.01% to 90% by weight of the total composition.
• an agrochemical composition comprising Pyroxasulfone having bulk density of about 0.40 g/cc to 0.90 g/cc. According to another embodiment, there is provided an agrochemical composition comprising Pyroxasulfone having D50 particle size value of less than about 200mih. In another embodiment, the agrochemical composition comprising Pyroxasulfone having D50 particle size value of less than about 150mih.
• Pyroxasulfone prepared according to present invention can be processed into an agricultural composition of various dosage forms by conventionally known methods.
• the present compositions are formulated as water dispersible granules.
• compositions using Pyroxasulfone produced according to present invention noted the ease of making compositions using Pyroxasulfone produced according to present invention.
• compositions of Pyroxasulfone obtained according to present invention are capable of dispersing quickly in water. According to an embodiment the compositions of Pyroxasulfone obtained according to present invention leads to optimum suspensibility while dispersed in water.
• the composition prepared is a water dispersible granule comprising Pyroxasulfone, at least one dispersing agent and at least one wetting agent.
• the dispersing agent/ wetting agent used is selected from, but not limited to, group comprising of anionic, cationic or zwitterionic and/or non-ionic surface-active compounds (surfactants) or combinations thereof, preferably anionic surfactant is used.
• anionic surfactants include: anionic derivatives of fatty alcohols having 10-24 carbon atoms in the form of ether carboxylates, sulfonates, sulfates, and phosphates, and their inorganic salts (e.g., alkali metal and alkaline earth metal salts) and organic salts (e.g., salts based on amine or alkanolamine); anionic derivatives of copolymers consisting of EO(ethylene oxide), PO (propylene oxide) and/or BO (butylene oxide) units, in the form of ether carboxylates, sulfonates, sulfates, and phosphates, and their inorganic salts (e.g., alkali metal and alkaline earth metal salts) and organic salts (e.g., salts based on amine or alkanolamine) or acrylic/styrene copolymers, methacrylic copolymers; linear (Cs-Cis) alcohol derivative and
• sulfosuccinates and their derivatives/salts acrylic/styrene copolymers; salts of lignin sulfonic acid are used.
• the composition may further comprise a defoamer.
• the defoamer used is selected from, but not limited to, group comprising of aqueous emulsion with polysiloxane and emulsifier, silicone oil and magnesium stearate or a suitable combination thereof.
• the water dispersible granule comprising Pyroxasulfone is prepared by a process comprising: a) mixing Pyroxasulfone with wetting agent/s and dispersing agent/s as required; b) milling the mixture in a suitable equipment to obtain a powder having a particle size D90 ⁇ 15 pm; and c) granulating the powder by suitable means and drying the granules obtained.
• an agrochemical composition comprising Pyroxasulfone prepared according to the present process and characterized by an X-ray powder diffraction pattern exhibiting at least three peaks selected from 9.90°, 17.72°, 17.94°, 19.91°, 20.36°, 20.60°, 21.76°, 22.09°, 22.31°, 22.70°, 25.10°, 25.41°, 26.57°, 27.01°, 28.40°, and 30.18° ⁇ 0.2° 2Q.
• the water dispersible granule comprising Pyroxasulfone is characterized by an X-ray powder diffraction pattern exhibiting at least three peaks selected from 9.90°, 17.72°, 17.94°, 19.91°, 20.36°, 20.60°, 21.76°, 22.09°, 22.31°, 22.70°, 25.10°, 25.41°, 26.57°, 27.01°, 28.40°, 30.18° ⁇ 0.2° 2Q.
• the present invention provides a simple, cost-effective and industrially viable alternative route to synthesis of Pyroxasulfone through preparation of intermediate compound of formula (I)
• Said process of present invention employees use of easily available raw materials.
• X-ray powder diffraction method pattern was carried out on Instrument: Bruker make 2 nd generation D2 Phaser Powder X-Ray diffractometer; Operated at: 30.0kV, 10mA;
• Chloride content of compound 12.48%, which corresponds to mono HC1 salt (Chloride content was calculated by HPLC)
• reaction mass was cooled to 55-60°C followed by addition of 0.0098mol of 17% sodium bisulphite solution. The mixture was then stirred for 30 minutes and 0.024mol of 48% sodium hydroxide solution was added to it. The mixture was again stirred for 5-10 minutes, and the layers were separated. The organic layer was then added to preheated 0.583mol of water and the temperature of mixture was raised to 90-95 °C. The acetonitrile in the mixture was distilled out. To the reaction mass at 80-90°C was then added 0.221mol of isopropyl alcohol and maintained for one hour. The mixture was then cooled 20-30°C to precipitate product. The precipitated product was filtered, washed with mixture of isopropyl alcohol and water and dried to yield 87% of Pyroxasulfone.
• WDG Water dispersible granules
• Pyroxasulfone along with wetting agent/s and dispersing agent/s were taken in ribbon blender and blended for 30 minutes. After blending, the powder was milled in air jet mill to achieve milled powder having particle size D90 ⁇ 15pm. The milled powder was then post blended in ribbon blender to form homogenous mixture. This mixture and required amount of Defoamer water solution (15 to 20 %) were taken in dough maker to make dough suitable for extrusion. Th dough was then extruded using extruder such as basket extruder by using required aperture size of 0.5 to 0.8 mm. The extruded granules were dried in fluid bed dryer to reduce moisture content below 2% and then sieved to get final product. The final product was characterised by X-ray powder diffraction pattern.
• Example 12 Preparation of water dispersible granules comprising Pyroxasulfone + Metribuzin
• WDG Water dispersible granules
• Example 13 Preparation of water dispersible granules comprising Pyroxasulfone + Metribuzin
• WDG Water dispersible granules

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