WO2018082456A1

WO2018082456A1 - A novel form of penoxsulam, a process for its preparation and use of the same

Info

Publication number: WO2018082456A1
Application number: PCT/CN2017/107092
Authority: WO
Inventors: James Timothy Bristow
Original assignee: Jiangsu Rotam Chemical Co Ltd
Current assignee: Jiangsu Rotam Chemical Co Ltd
Priority date: 2016-11-07
Filing date: 2017-10-20
Publication date: 2018-05-11
Anticipated expiration: 2019-05-07
Also published as: CN109803970A; CN109803970B; GB2555635B; GB2555635A

Abstract

The present invention describes the crystalline form of penoxsulam of formula (I), the crystal preparation process, the analyses of the crystal through various analytical methods and using the crystal to prepare stable agrochemical formulation. The invention also describes the use of various solvents towards the crystalline form preparation conditions.

Description

A NOVEL FORM OF PENOXSULAM, A PROCESS FOR ITS PREPARATION AND USE OF THE SAME

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to GB Patent Application No. 1618734.6, titled “A NOVEL FORM OF PENOXSULAM, A PROCESS FOR ITS PREPARATION AND USE OF THE SAME” , filed with Intellectual Property Office (UK) on November 7, 2016, the entire contents of which are incorporated herein by reference.

FIELD

The present invention relates to a crystalline form of 3- (2, 2-difluoroethoxy) -N- (5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidin-2-yl) -α, α, α-trifluorotolu ene-2-sulfonamide (penoxsulam) , to its preparation processes and to its use in agrochemical preparations.

BACKGROUND

3- (2, 2-difluoroethoxy) -N- (5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidin-2-yl) -α, α, α-trifluorotoluene-2-sulfonamide (penoxsulam) , is a herbicide from the triazolo pyrimidine sulfonanilide family. It is a selective and highly active herbicide to control grasses, broadleaved weeds and sedges on rice. It is applied through the field or foliage using a suitable formulated product and absorbed through the root or foliage of the plants, respectively.

Penoxsulam has molecular formula of C₁₆H₁₄F₅N₅O₅S. Its chemical structure is:

The commercially available penoxsulam, which is usually manufactured by the process described in U.S. Patent No. 5858924, which is incorporated herein by reference for all purposes, is present in an amorphous state. It has been found that amorphous penoxsulam is not suitable for being prepared as compositions or formulations as it is extremely susceptible to hydrolysis due to its unstable nature. It will undergo significant hydrolysis when dissolved or dispersed in water. Hydrolysis can even occur during storage, particularly where the compound is exposed to moisture. As a result, the stability of penoxsulam is of great concern for the commercially available formulations. Therefore, there is a need to provide a novel form of penoxsulam with increased stability in formulations.

SUMMARY

In attempt to resolve some or all of the problems with existing amorphous form of penoxsulam, a new and stable crystalline form of penoxsulam has been prepared.

Aspects of the invention relate to a crystalline modification of 3- (2, 2-difluoroethoxy) -N- (5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidin-2-yl) -α, α, α-trifluorotolu ene-2-sulfonamide (penoxsulam) .

In a first aspect, the present invention provides a novel crystalline form of 3- (2, 2-difluoroethoxy) -N- (5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidin-2-yl) -α, α, α-trifluorotoluene-2-sulfonamide (penoxsulam) , termed “crystalline modification I” , exhibiting at least 4 of the following reflexes, in any combination, as 2θ±0.2 degree in an X-ray powder diffractogram (X-RPD) recorded using Cu—Kα radiation at 25℃:

2θ ＝ 6.19 ± 0.2 (1)

2θ ＝ 10.70 ± 0.2 (2)

2θ ＝ 11.05 ± 0.2 (3)

2θ ＝ 11.47 ± 0.2 (4)

2θ ＝ 17.21 ± 0.2 (5)

2θ ＝ 18.75 ± 0.2 (6)

2θ ＝ 20.28 ± 0.2 (7)

2θ ＝ 23.38 ± 0.2 (8)

2θ ＝ 23.59 ± 0.2 (9)

2θ ＝ 24.50 ± 0.2 (10)

2θ ＝ 24.66 ± 0.2 (11)

2θ ＝ 25.10 ± 0.2 (12)

2θ ＝ 27.57 ± 0.2 (13)

2θ ＝ 29.65 ± 0.2 (14)

In an embodiment, the crystalline modification according to the first aspect of the invention, exhibits at least 4, 5, 6, 7, 8 or all of the reflexes, in any combination, from the following:

2θ ＝ 6.19 ± 0.2 (1)

2θ ＝ 11.47 ± 0.2 (4)

2θ ＝ 18.75 ± 0.2 (6)

2θ ＝ 20.28 ± 0.2 (7)

2θ ＝ 24.50 ± 0.2 (10)

2θ ＝ 24.66 ± 0.2 (11)

2θ ＝ 27.57 ± 0.2 (13)

2θ ＝ 29.65 ± 0.2 (14)

In a second aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to the first aspect of the invention, exhibiting an infrared (IR) spectrum with characteristic functional group vibration peaks at wavenumbers (cm-1, ±0.2％) of 3360.72, 2925.19, 1637.23 and 1534.23 cm^-1.

In a third aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to the first or second aspect of the invention, exhibiting a melting point of 227℃ to 232℃.

In a fourth aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to any one of the first to third aspects of the invention, exhibiting a differential scanning calorimetry (DSC) profile having an endothermic melting peak with onset at 228℃ and peak maximum at 229℃, further optionally with a melting enthalpy of 80 J/g.

In a fifth aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to any one of the first to fourth aspects of the invention, characterized by X-ray powder diffraction pattern as substantially shown in FIG. 2, and/or characterized by an IR spectrum as substantially shown in FIG. 1, and/or characterized by a DSC thermogram as substantially shown in FIG. 3.

In a sixth aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to any one of the first to fifth aspects of the invention, obtainable by the process as substantially as described in Example 2 or 3.

In a seventh aspect, the present invention provides a crystalline modification I of penoxsulam, optionally according to any one of the first to sixth aspects of the invention, obtainable by the process of the eighth aspect of the invention.

It has been found that the present crystalline modification I of penoxsulam has a significant increase in its hydrolysis stability, which significantly reduces the hydrolysis problems encountered in current commercially available formulations. In addition, it is found that the crystalline modification I of penoxsulam is easier to comminute or grind compared to amorphous penoxsulam prepared in accordance with the disclosure of US PAT. NO. 5,858,924. In addition, the crystalline modification I has a lower tendency to hydrolysis after exposure to moisture compared to the amorphous state described in US PAT. NO. 5,858,924. This allows the preparation of commercial formulations such as suspension concentrates (SC) , oil-based suspension concentrates (OD) , water-dispersible granules (WG) and water-soluble granules (SG) . By virtue of its high hydrolysis stability, the crystalline modification I of penoxsulam gives the desired long storage period to its formulations. Hence, it is possible to prepare any formulations of penoxsulam of crystalline modification I, which will be disclosed hereinafter.

In an eighth aspect, the present invention provides a process for preparing a crystalline modification I of penoxsulam comprising steps of:

i) dissolving penoxsulam in a solvent, or mixture of solvents；

ii) precipitating the dissolved compound into crystalline modification I of penoxsulam； and

iii) isolating the precipitated crystalline modification I.

In an embodiment of the eighth aspect of the invention, the penoxsulam in step i) is amorphous penoxsulam.

Methods for preparing amorphous penoxsulam are well known in the art. Amorphous penoxsulam is manufactured and available on a commercial scale. A particularly suitable method for preparing amorphous penoxsulam is described in US5858924.

In an embodiment of the eighth aspect of the invention, the solvent is selected from the group consisting of halogenated hydrocarbons (for example, chlorobenzene, bromobenzene, dichlorobenzene, chlorotoluene and trichlorobenzene) , ethers (for example, ethyl propyl ether, n-butyl ether, anisole, phenetole, cyclohexyl methyl ether, dimethyl ether, diethyl ether, dimethyl glycol, diphenyl ether, dipropyl ether, diisopropyl ether, di-n-butyl ether, diisobutyl ether, diisoamyl ether, ethylene glycol dimethyl ether, isopropyl ethyl ether, methyl tert-butyl ether, tetrahydrofuran, methyltetrahydrofuran, dioxane, dichlorodiethyl ether, methyl-tetrahydrofuran, polyethers of ethylene oxide and/or propylene oxide) , nitrated hydrocarbons (for example, nitromethane, nitroethane, nitropropane, nitrobenzene, chloronitrobenzene and o-nitrotoluene) , aliphatic, cycloaliphatic or aromatic hydrocarbons (for example, pentane, n-hexane, n-heptane, n-octane, nonane) , cymene, petroleum fractions having a boiling range of from 70℃ to 190℃, cyclohexane, methylcyclohexane, petroleum ether, ligroin, octane, benzene, toluene and xylene, esters (for example, malonates, acetic acid n-butyl ester (n-butyl acetate) , methyl acetate, ethyl acetate, isobutyl acetate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate and ethylene carbonate) , and aliphatic alcohols (for example, methanol, isopropyl alcohol, ethanol, n-propanol, isopropanol, n-butanol and tert-amyl alcohol) , mesitylene, diethyl ketone, methyl ethyl ketone and mixtures thereof.

In an embodiment of the eighth aspect of the invention, the solvent is selected from the group consisting of nitrobenzene, toluene, xylene, benzene, chlorobenzene, dichlorobenzene, ethyl benzene, trifluoro methyl benzene, mesitylene, ether, methyl ethyl ketone.

In an embodiment of the eighth aspect of the present invention, the solvent is selected from the group consisting of methyl ethyl ketone or xylene or a mixture thereof.

According to an embodiment of the eighth aspect of the present invention, crystalline modification I of penoxsulam is prepared by dissolving amorphous penoxsulam in a solvent or a solvent mixture as a concentrated solution by heating from ambient temperature to a temperature at or below the reflux temperature of the solvent or the solvent mixture. Optionally, the concentrated solutions can be prepared at the reflux temperature of the solvents. The concentration of the solution depends on the solubility of penoxsulam in the corresponding solvent or solvent mixture.

In an embodiment of the eighth aspect of the invention, the concentrated homogeneous solution thus prepared as in step (i) is then cooled to room temperature or to a temperature of about 0℃ to 20℃ to crystallize the desired crystalline form from the solvent. The crystalline modification I of penoxsulam can also be crystallized out by concentrating the homogeneous solution by removing the solvent or solvent mixture to a certain volume with or without applying vacuum and cooling to below the reflux temperature of the solvent or the solvent mixture.

In an embodiment of the eighth aspect of the invention, crystalline modification I of penoxsulam can also be effected by adding seed crystals of the desired crystalline form during crystallization into a solution prepared in step (i) , which can promote or accelerate the crystallization.

The seed crystal amount added to the concentrated solution is typically in the range of 0.001％to 10％by weight, optionally 0.001％to 2.5％by weight, further optionally 0.005 to 0.5％by weight based on the weight of penoxsulam used for the preparation of concentrated solution in step (i) . Optionally, the seed crystals are added to the concentrated solution at the temperature below the boiling point of the corresponding solvent or the solvent mixture.

In an embodiment of the eighth aspect of the invention, the precipitated crystalline modification I of penoxsulam obtained from step (ii) is isolated by the usual solid component separating techniques from solutions, such as filtration, centrifugation or decantation. Then, the isolated solid will be washed with solvent one or more times. Optionally, the solvent employed in the washing stage consists of one or more components of the solvent or solvent mixture employed for the preparation of concentrated solution in step (i) , as described hereinbefore. Methyl ethyl ketone and xylene are particularly suitable solvents for washing the recovered solid of penoxsulam. The washing is usually carried out using the corresponding solvent or solvent mixture between room temperature and 0℃, depending on the solubility of the crystal in order to avoid the loss of crystal as far as possible in the corresponding washing solvent.

In an embodiment of the eighth aspect of the invention, crystalline modification I of penoxsulam is dissolved and recrystallized. The washings and/or the solvent of crystallization in any of the methods may be concentrated to obtain solid penoxsulam which may be recycled.

In a ninth aspect, the present invention provides a crystalline modification I of penoxsulam obtained according to the eighth aspect of the invention, having a crystalline penoxsulam content of at least 98％by weight.

In a tenth aspect, the present invention provides a composition comprising the crystalline modification I of penoxsulam according to any one of the first to seventh and ninth aspects of the invention, and at least one auxiliary.

In an eleventh aspect, the present invention provides a use of the crystalline modification I of penoxsulam according to any one of the first to seventh and ninth aspects of the invention, or a composition according to the tenth aspect of the invention, for weed control.

In an embodiment of the tenth aspect of the invention, the amount of the crystalline modification I of penoxsulam is less than 75％by weight of the composition, optionally less than 50％by weight of the composition, further optionally less than 30％by weight of the composition, still further optionally about 10％to 25％by weight of the composition.

The use of amorphous penoxsulam as a herbicide is known in the art and is used on a commercial scale. It has been found that the crystalline modification I of penoxsulam is also active in controlling undesirable plant growth, such as weeds. As a result, the techniques of formulating and applying penoxsulam known in the art with respect to amorphous penoxsulam, for example as disclosed in the prior art documents discussed hereinbefore, can also be applied in an analogous manner to penoxsulam in the crystalline modification I of the invention.

Accordingly, the invention provides a herbicidal composition comprising penoxsulam in the crystalline modification I as defined hereinbefore.

The invention additionally provides processes for preparing compositions for controlling undesirable plants, such as weeds using the crystalline modification I of penoxsulam.

The invention also provides a method for controlling unwanted plant growth, comprising applying to the plant, plant part, or surroundings of the plant, a herbicidally effective amount of crystalline modification I of penoxsulam according to any one of the first to seventh and ninth aspects of the invention, or a composition according to the tenth aspect of the invention. Accordingly, this provides for controlling undesirable plants in plants, plant parts, and/or their surroundings, comprising applying to the foliage or fruit of the plant, plant part, or surroundings of the plant, a herbicidally effective amount of crystalline modification I of penoxsulam.

In an embodiment of the tenth aspect of the invention, the composition is in the form of a suspension concentrate (SC) , oil-based suspension concentrate (OD) , water-soluble granule (SG) , dispersible concentrate (DC) , emulsifiable concentrate (EC) , emulsion seed dressing, suspension seed dressing, a granule (GR) , a microgranule (MG) , a suspoemulsion (SE) or water-dispersible granule (WG) . Crystalline modification I of penoxsulam can be included into these customary formulations in a known manner using suitable auxiliaries, carriers and solvents and the like.

In an embodiment of the tenth aspect of the invention, the composition is in the form of an oil-based suspension concentrate (OD) , a water-soluble granule (SG) , or a water-dispersible granule (WG) .

In an embodiment of the tenth aspect of the invention, the crystalline modification I of penoxsulam may be present in a concentration sufficient to achieve the required dosage when applied to plants or the loci thereof, desirably in a concentration of about 0.1％to 70％by weight of the total mixture. The formulations are prepared, for example, by extending the crystalline modification I of penoxsulam with water, solvents and carriers, using, if appropriate, emulsifiers and/or dispersants, and/or other auxiliaries.

These formulations are prepared by mixing the crystalline modification I of penoxsulam with customary additives, for example, one or more of liquid diluents, solid diluents, wetting agents, dispersants, thickening agents, antifreeze agents, antifoaming agents, biocides and any necessary adjuvants and other formulation ingredients.

Liquid diluents include, but are not limited to, water, N, N-dimethylmamide, dimethyl sulfoxide, N-alkylpyrrolidone, ethylene glycol, polypropylene glycol, propylene carbonate, dibasic esters, paraffines, alkylbenzenes, alkyl naphthalenes, glycerine, triacetine, oils of olive, castor, linseed, sesame, corn, peanut, cotton-seed, soybean, rape-seed and coconut, ketones such as cyclohexanone, 2-heptanone, isophorone and 4-hydroxy-4-methyl-2-pentanone, acetates such as hexyl acetate, heptyl acetate and octyl acetate, and alcohols such methanol, cyclohexanol, decanol, benzyl and tetrahydrofurfuryl alcohol, and mixtures thereof.

Solid diluents can be water-soluble or water-insoluble. Water-soluble solid diluents include, but are not limited to, salts such as alkali metal phosphates (e.g.， sodium dihydrogen phosphate) , alkaline earth phosphates, sulfates of sodium, potassium, magnesium and zinc, sodium and potassium chloride, sodium acetate, sodium carbonate and sodium benzoate, and sugars and sugar derivatives such as sorbitol, lactose, sucrose and mannitol. Examples of water-insoluble solid diluents include, but are not limited to clays, synthetic and diatomaceous silicas, calcium and magnesium silicates, titanium dioxide, aluminum, calcium and zinc oxide, and mixtures thereof.

Wetting agents include, but are not limited to, alkyl sulfosuccinates, laureates, alkyl sulfates, phosphate esters, acetylenic diols, ethoxyfluornated alcohols, ethoxylated silicones, alkyl phenol ethyoxylates, benzene sulfonates, alkyl-substituted benzene sulfonates, alkyl a-olefin sulfonates, naphthalene sulfonates, alkyl-substituted napthalene sulfonates, condensates of naphthalene sulfonates and alkyl-substituted naphthalene sulfonates with formaldehyde, and alcohol ethoxylates, and mixtures thereof. Alkyl naphthalene sulphonates, sodium salts are particularly useful for the composition of the invention.

Dispersants include, but are not limited to, sodium, calcium and ammonium salts of ligninsulfonates (optionally polyethoxylated) ； sodium and ammonium salts of maleic anhydride copolymers； sodium salts of condensed phenolsulfonic acid； and naphthalene sulfonate-formaldehyde condensates. Of note are compositions comprising up to 10％by weight of dispersant. Ligninsulfonates such as sodium ligninsulfonates, naphthalene sulfonate-formaldehyde condensates such as naphthalenesulfonic acid, polymers with formaldehyde, and sodium salts are particularly useful for the composition of the invention.

Thickening agents include, but are not limited to, guar gum, pectin, casein, carrageenan, xanthan gum, silica, alginates, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and carboxymethylcellulose. Synthetic thickening agents include derivatives of the former categories, and also polyvinyl alcohols, polyacrylamides, polyvinylpyrrolidones, various polyethers, their copolymers as well as polyacrylic acids and their salts. Silica is particularly useful for the composition of the invention.

Suitable antifreeze agents are liquid polyols, for example ethylene glycol, propylene glycol or glycerol. The amount of antifreeze agents is generally from about 1％to about 20％by weight, in particular from about 5 to about 10％by weight, based on the total weight of the composition.

Antifoaming agents include all substances which can normally be used for this purpose in agrochemical compositions. Suitable anti-foam agents are known in the art and are available commercially. Particularly preferred antifoam agents are mixtures of polydimethylsiloxanes and perfluroalkylphosphonic acids, such as the silicone antifoaming agents available from GE or Compton.

Biocide may also be added to the composition according to the invention. Suitable Biocides are those based on isothiazolones, for example

from ICI or

RS from Thor Chemie or

MK from Rohm &Haas. The amount of biocides is typically from 0.05％to 0.5％by weight, based on the total weight of the composition.

Other formulation ingredients can also be used in the present invention such as dyes, drying agents, and the like. These ingredients are known to one skilled in the art.

In an embodiment of the tenth aspect of the invention, the crystalline modification I of penoxsulam can be present in formulations and in its use forms, prepared from these formulations, and as a mixture with other active compounds (such as insecticides, attractants, sterilizing agents, bactericides, acaricides, nematicides, fungicides, growth-regulating substances, herbicides, safeners, fertilizers and semiochemicals) or with agents for improving plant properties.

Preferred mixing partners of the crystalline modification I of penoxsulam include cyhalofop-butyl, substituted triazolopyrimidinesulfonamide compounds, such as diclosulam, cloransulam-methyl, flumetsulam. Other herbicides such as acifluorfen, bentazon, chlorimuron, clomazone, lactofen, carfentrazone-methyl, fumiclorac, fluometuron, fomesafen, imazaquin, imazethapyr, linuron, metribuzin, fluazifop, haloxyfop, glyphosate, glufosinate, 2, 4-D, acetochlor, metolachlor, sethoxydim, nicosulfuron, clopyralid, fluroxypyr, metsulfuron-methyl, amidosulfuron, tribenuron-methyl, thifensulfuron-methyl, flupyrsulfuron-methyl-sodium mesosulfuron-methyl, iodosulfuron-methyl-sodium, rimsulfuron, halosulfuron-methyl, trifloxysulfuron-sodium and chlorsulfuron can also be employed. It is generally preferred to use the compounds in conjunction with other herbicides that have similar crop selectivity. It is further usually preferred to apply the herbicides at the same time, either as a combination formulation or as a tank mix. Particular preferred mixing partner is cyhalofop-butyl. All plants and plant parts can be treated in accordance with the invention. In the present context, plants are to be understood as meaning all plants and plant populations such as desired and undesired wild plants or crop plants (including naturally occurring crop plants) . Crop plants can be plants which can be obtained by conventional breeding and optimization methods, by biotechnological and genetic engineering methods, or by combinations of these methods, including the transgenic plants and the plant cultivars which can or cannot be protected by plant breeders'rights. Plant parts are to be understood as meaning all parts and organs of plants above and below the ground, such as shoot, leaves, needles, stalks, stems, flowers, fruit bodies, fruits, seeds, roots, tubers and rhizomes. Harvested materials, and vegetative and generative propagation materials, for example, cutting, tubers, meristem tissue, rhizomes, offsets, seeds, single and multiple plant cells and any other plant tissues, are also included.

The benefits of the invention are seen most when the herbicidal composition is applied to kill weeds in growing crops of useful plants: such as sugarcane, corn, cereals, rice, maize, sorghum, cotton, canola, turf, barley, potato, sweet potato, sunflower, rye, oats, wheat, soybean, soya, sugar beet, tobacco, safflower, tomato, alfalfa, pineapple, cucurbits cassava and pastures. In an embodiment of the invention, rice and cereals are particularly suitable for treatment.

Throughout the description and claims of this specification, the words “comprise” and variations of the words, for example “comprising” and “comprises” , mean “including but not limited to” , and do not exclude other moieties, additives, components, integers or steps. Moreover the singular encompasses the plural unless the context otherwise requires: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Preferred features of each aspect of the invention may be as described in connection with any of the other aspects. Other features of the invention will become apparent from the following examples. Generally speaking the invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims and drawings) . Thus features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. Moreover unless stated otherwise, any feature disclosed herein may be replaced by an alternative feature serving the same or a similar purpose.

Where upper and lower limits are quoted for a property then a range of values defined by a combination of any of the upper limits with any of the lower limits may also be implied.

In this specification, references to properties are –unless stated otherwise –to properties measured under ambient conditions, i.e. at atmospheric pressure and at a temperature of about 20℃.

As used herein, the term “about, ” when used in connection with a numerical amount or range, means somewhat more or somewhat less than the stated numerical amount or range, to a deviation of ± 10％of the stated numerical amount or endpoint of the range.

The term “crystalline” , as used herein, refers to a solid state form wherein molecules are arranged to form a crystal lattice comprising distinguishable unit cells. In general, crystalline material may, for example, be identified by yielding diffraction peaks when subjected to X-ray radiation and/or exhibiting an endothermic melting peak profile with a characteristic sharp peak under differential scanning calorimetry (DSC) .

“Surrounding” , as used herein, refers to the place on which the plants are growing, the place on which the plant propagation materials of the plants are sown or the place on which the plant propagation materials of the plants will be sown.

Treatment of the plants and plant parts with the compositions or formulations of the inventions is carried out directly or by allowing the compositions or formulations to act on their surroundings, habitat or storage space by the customary treatment methods. Examples of these customary treatment methods include dipping, spraying, vaporizing, fogging, broadcasting, painting on in the case of propagation material, and applying one or more coats particularly in the case of seed.

"Precipitation" as used herein, refers to the sedimentation of a solid material (a precipitate) , including the sedimentation of a crystalline material, from a liquid solution in which the solid material is present in amounts greater than its solubility in the amount of liquid solution.

All percentages are given in weight ％unless otherwise indicated.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more clearly understood by reference to the drawings, which are described below, and are intended to exemplify and illustrate, but not to limit, the scope of the invention, wherein:

FIG. 1 is a an infrared (IR) spectrograph of crystalline modification I of penoxsulam；

FIG. 2 is a X-ray powder diffractogram of crystalline modification I of penoxsulam；

FIG. 3 is a Differential Scanning Calorimetry (DSC) thermogram of crystal modification I of penoxsulam；

FIG. 4 is a X-ray powder diffractogram of amorphous penoxsulam.

DETAILED DESCRIPTION

Embodiments of the present invention will now be described by the following examples, and in which the following measurement techniques have been employed, and which the examples are provided for illustrative purposes only, and not intended to limit the scope of the disclosure.

All X-ray diffractograms were determined using powder diffractometer in reflection geometry at 25℃, using the following acquisition parameters:

X’Pert Pro MPD from PANalytical B. V.
Theta compensating slit and graphite monochromator
Copper (K-alpha) radiation, 40 kV, 40 mA
Step size: 0.03 degree 2-theta
Count time: 1.0 second
Maximum peak intensity: 1705 counts per second
Scan range: 3-60 degrees 2-theta

The IR spectrum was measured with the resolution of 4 cm^-1 and with the number of scans of 16 for the crystallized samples. The crystalline modification I of penoxsulam can be identified by its characteristic functional group vibration peaks at wavenumbers (cm^-1, ±0.2％) of 3360.72, 2925.19, 1637.23 and 1534.23 as shown in FIG. 1.

All IR spectra were obtained using the following acquisition parameters:

All DSC thermograms were obtained using the following acquisition parameters:

Examples

Example 1: Preparation of amorphous penoxsulam in accordance with the disclosure of U.S. Pat. No. 5,858,924 with necessary modification in Example 20

A mixture of 93.8mmol of 2-amino-5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidine, 7.6mmol of 2- (2, 2-difluoroethoxy) -6- (trifluoromethyl) benzenesulfonyl chloride, and 10mL of dry acetonitrile was prepared and to this was added at ambient temperature with stirring and means to exclude moisture from the system 0.61mL (7.6mmol) of dry pyridine, 43 μL (0.6mmol) of dry dimethyl sulfoxide, and a small quantity of dry 4A molecular sieves. The mixture was stirred for 5 days. Another 1.0g (3.4mmol) of 2- (2, 2-difluoroethoxy) -6- (trifluoromethyl) benzenesulfonyl chloride and 0.30mL (3.5mmol) of dry pyridine were added and the mixture stirred for another 2 days. Another 0.30mL (3.5mmol) of dry pyridine was added and stirring continued for 4 more days. The mixture was then diluted with 100mL of dichloromethane and the resulting mixture was washed with 2×100 mL of 2N aqueous hydrochloric acid, dried over magnesium sulfate, and concentrated by evaporation under reduced pressure. The tan solid residue was chromatographed on silica gel eluting with a mixture of dichloromethane and ethanol to obtain 54％of penoxsulam.

Scheme 1. Synthesis of penoxsulam

As shown in FIG. 4, the X-ray powder diffraction pattern of the resulting penoxsulam product has no significant signals, which indicates that the penoxsulam product prepared in accordance with the disclosure of U.S. Pat. No. 5,858,924 is amorphous.

Example 2: Preparation of the crystalline modification I of penoxsulam

Crystallization from methyl ethyl ketone

10g of amorphous penoxsulam sample prepared in example 1 was taken in a 3-neck round bottom flask along with 50mL of methyl ethyl ketone and the resulting slurry was heated to 65℃ to get a homogeneous solution. The insoluble particles, if any, were filtered and the solution was slowly cooled to to 20～25℃. Upon cooling, fine crystals were formed and the resulting heterogeneous mixture was stirred at 20℃ for 2h. Then, the slurry was filtered and washed with 3 mL of methyl ethyl ketone at 20℃. The filtered crystals were dried under vacuum at 40℃. The crystals thus obtained were having a purity of >98％and the recovered product as crystal was found to be not less than 90％yield.

The obtained crystals were analyzed by DSC, IR spectrometry and X-ray powder diffraction and found to crystalline modification I of penoxsulam as shown in FIG. 1, FIG. 2 and FIG. 3, respectively.

The DSC thermogram of penoxsulam exhibited an endothermic melting peak with onset at 227.5℃ and peak maximum at 229.2℃, further optionally with a melting enthalpy of 79.66 J/g as shown in FIG. 3.

The IR spectrum of the crystalline modification I of penoxsulam exhibited the functional group characteristic vibrations peaks at wavenumbers of one or more of 3360.72, 2925.19, 1637.23 and 1534.23 cm^-1 as shown in FIG. 1.

The X-ray powder diffractogram of the crystalline modification I of penoxsulam crystals exhibited the reflexes in Figure 2 and the values are summarized in Table 1.

Table 1

Example 3: Preparation of the crystalline modification I of penoxsulam

Crystallization from xylene

5g of amorphous penoxsulam sample prepared in example 1 was taken in a 3-neck round bottom flask along with 30mL of xylene and the resulting slurry was heated to 83℃ to get a homogeneous solution. The insoluble particles, if any, were filtered and the solution was slowly cooled to 20～25℃. Upon cooling, fine crystals were formed and the resulting heterogeneous mixture was stirred at 20℃ for 2h. Then, the slurry was filtered, washed with 3mL of xylene at 20℃. The filtered crystals were dried under vacuum at 45℃. The crystalline product thus obtained were having a purity of >98％and the the recovered product as crystal was found to be not less than 80％yield.

The obtained crystals were characterized as being the crystalline modification I of penoxsulam using IR spectrometry, X-ray powder diffraction and DSC as described in Example 2.

Example 4: Preparation of oil based suspension concentrate (OD) formulation

All the components listed in Table 2 below were mixed uniformly and ground with a Dyno-Mill (manufactured by Willy A. Bachofen AG) to obtain an oil based suspension concentrate.

Table 2

Example 5: Preparation of oil based suspension concentrate (OD) formulation

All the components listed in Table 3 below were mixed uniformly and ground with a Dyno-Mill (manufactured by Willy A. Bachofen AG) to obtain an oil based suspension concentrate.

Table 3

Example 6: Preparation of soluble granules (SG)

All the components listed in Table 4 below were mixed, blended and milled in a high-speed rotary mill. Sufficient water was added to obtain an extrudable paste. The paste was extruded through a die or screen to form an extrudate. The wet extrudate was dried at 70℃ in a vacuum oven and then sifted through 0.71mm～2mm screens to obtain the product granules.

Table 4

Example 7: Preparation of water dispersible granules (WG)

All the components listed in Table 5 below were mixed, blended and milled in a high-speed rotary mill. Sufficient water was added to obtain an extrudable paste. The paste was extruded through a die or screen to form an extrudate. The wet extrudate was dried at 70℃ in a vacuum oven and then sifted through 0.71mm～2mm screens to obtain the product granules.

Table 5

Example 8: Stability test

The stability of the penoxsulam in these compositions was determined by aging samples in heated ovens having the same atmosphere therein, and then comparing the penoxsulam content before and after aging to determine relative percentage of hydrolysis (RPH) . RPH was calculated by the following equation:

Penoxsulam content was determined by assaying the compositions with high-pressure liquid chromatography (HPLC) using reverse phase columns and eluants.

Samples prepared in Examples 4, 5, 6 and 7 were stored at 54℃ for 1 week. The procedures are followed according to CIPAC MT 46.3. The concentration of penoxsulam was measured at the end of each storage time by HPLC. The results are listed in Table 6.

Table 6

It is surprisingly found that the crystalline modification I of penoxsulam is extremely stable after storage at 54℃ for 1 week. It has a reduced tendency to hydrolysis compared to the amorphous form. The relative percentage of hydrolysis (RPH) in these tests for crystalline modification I of penoxsulam was 3％or less, 2％or less, and 1％or less. By comparison, the corresponding RPH when amorphous penoxsulam was used was no less than 45％. There was up to about 15 times less hydrolysis, up to about 20 times less hydrolysis, up to about 25 times less hydrolysis, up to about 45 times less hydrolysis when the crystalline modification I of penoxsulam was used when compared to the amorphous penoxsulam； this covering a range of about 15 to 45 times less hydrolysis resulted. For these reasons, it is highly suitable for preparing commercial formulations where such hydrolysis can lead to a loss of productivity.

Claims

A crystalline modification of 3- (2, 2-difluoroethoxy) -N- (5, 8-dimethoxy [1, 2, 4] triazolo [1, 5-c] pyrimidin-2-yl) -α, α, α-trifluorotoluene-2-sulfonamide (penoxsulam) .
The crystalline modification according to claim 1, exhibiting at least four of the following reflexes, in any combination, as 2θ ± 0.2 degree in an X-ray powder diffractogram recorded using Cu—Kα radiation at 25℃:

2θ ＝ 6.19 ± 0.2                     (1)

2θ ＝ 10.70 ± 0.2                    (2)

2θ ＝ 11.05 ± 0.2                    (3)

2θ ＝ 11.47 ± 0.2                    (4)

2θ ＝ 17.21 ± 0.2                    (5)

2θ ＝ 18.75 ± 0.2                    (6)

2θ ＝ 20.28 ± 0.2                    (7)

2θ ＝ 23.38 ± 0.2                    (8)

2θ ＝ 23.59 ± 0.2                    (9)

2θ ＝ 24.50 ± 0.2                    (10)

2θ ＝ 24.66 ± 0.2                    (11)

2θ ＝ 25.10 ± 0.2                    (12)

2θ ＝ 27.57 ± 0.2                    (13)

2θ ＝ 29.65 ± 0.2                    (14) .
The crystalline modification of penoxsulam according to claim 1 or claim 2, exhibiting at least four of the following reflexes, in any combination, in an X-ray powder diffractogram recorded using Cu—Kα radiation at 25℃:

2θ ＝ 6.19 ± 0.2                     (1)

2θ ＝ 11.47 ± 0.2                    (4)

2θ ＝ 18.75 ± 0.2                    (6)

2θ ＝ 20.28 ± 0.2                    (7)

2θ ＝ 24.50 ± 0.2                    (10)

2θ ＝ 24.66 ± 0.2                    (11)

2θ ＝ 27.57 ± 0.2                    (13)

2θ ＝ 29.65 ± 0.2                    (14) .
The crystalline modification of penoxsulam according to claim 2 or claim 3 exhibiting at least five or at least six of said reflexes.
The crystalline modification of penoxsulam according to any preceding claims, exhibiting an IR spectrum with characteristic functional group vibrations peaks at wavenumbers (cm^-1, ±0.2％) of one or more of about 3360.72, 2925.19, 1637.23 and 1534.23cm^-1.
The crystalline modification of penoxsulam according to any preceding claims, exhibiting a melting point 227℃ to 232℃, optionally 228℃ to 230℃, further optionally about 229℃.
The crystalline modification of penoxsulam according to any preceding claims, exhibiting a differential scanning calorimetry (DSC) profile having an endothermic melting peak with onset at 228℃ and peak maximum at 229℃, further optionally with a melting enthalpy of 80 J/g.
The crystalline modification of penoxsulam according to any preceding claims, characterized by an X-ray powder diffraction pattern substantially as shown in FIG. 2, and/or characterized by an IR spectrum substantially as shown in FIG. 1, and/or characterized by a DSC substantially as shown in FIG. 3.
The crystalline modification of penoxsulam according to any preceding claims, obtainable by the process as substantially as described in Example 2 or 3.
The crystalline modification of penoxsulam according to any one of claims 1 to 8, obtainable by the process of any one of claims 11 to 16.
A process for the preparation of a crystalline modification of penoxsulam according to any one of claims 1 to 8 comprising:

i) dissolving penoxsulam in a solvent, or mixture of solvents；

ii) precipitating the dissolved compound into a crystalline modification of penoxsulam； and

iii) isolating the precipitated crystalline modification.
The process according to claim 11, where the penoxsulam in step i) is amorphous penoxsulam.
The process according to claim 11 or claim 12, wherein the solvent is selected from the group consisting of nitrobenzene, toluene, xylene, benzene, chlorobenzene, dichlorobenzene, ethyl benzene, trifluoro methyl benzene, mesitylene, ether, methyl ethyl ketone.
The process according to any one of claims 11 to 13, wherein the solvent is methyl ethyl ketone or xylene or a mixture thereof.
The process according to any one of claims 11 to 14, wherein step ii) is effected by concentration of the solvent and/or by cooling and/or by the addition of a solubility reducing solvent and/or by adding a seed crystal of the crystalline modification of penoxsulam.
The process according to claim 15, wherein step ii) is effected by cooling to about 0 to 20℃.
The crystalline modification of penoxsulam obtainable according to any one of claims 11 to 16 and having a crystalline penoxsulam content of at least 98％by weight.
A composition comprising the crystalline modification of penoxsulam according to any one of claims 1 to 10 and 17 and at least one auxiliary.
The composition according to claim 18, wherein the auxiliary is selected from the group consisting of liquid diluents, solid diluents, wetting agents, dispersants, thickening agents, antifreeze agents, antifoaming agents, biocides and any necessary adjuvants and other formulation ingredients.
The composition according to any one of claims 18 to 19, which is in form of a suspension concentrate (SG) , an oil-based suspension concentrate (OD) , water-soluble granules (SG) , a dispersible concentrate (DC) , an emulsifiable concentrate (EC) , an emulsion seed dressing, a suspension seed dressing, a granule (GR) , a microgranule (MG) , a suspoemulsion (SE) or a water-dispersible granule (WG) .
The composition according to claim 20, in form of an oil-based suspension concentrate, a water-soluble granule (SG) , or a water-dispersible granule (WG) .
The composition according to any of claims 18 to 21, which comprises crystalline modification of penoxsulam in an amount of less than 75％by weight.
The composition according to any of claims 18 to 22, which comprises crystalline modification of penoxsulam and cyhalofop-butyl.
Use of the crystalline modification of penoxsulam according to any of claims 1 to 10 or a composition according to any of claims 18 to 23 for weed control.