Process for production of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl) phenyl]-1-(1, 2, 4-triazol-1-yl) propan-2-ol

Abstract

The present invention relates to a process for the production of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl) phenyl]-1-(1, 2, 4-triazol-1-yl) propan-2-ol in high purity and yield, to a process for the production of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl) phenyl]-1-(1, 2, 4-triazol-1-yl) propan-2-ol.

Description

[0001] The present invention relates to a method for producing 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol with high purity and high yield.

[0002] 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol is an effective fungicide, which is described, for example, in WO 2014 / 108286 and WO 2015 / 091045. It is usually synthesized by reacting 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane with 1H-[1,2,4]-triazole. However, the reaction is not completely selective. In addition to the desired 1,2,4-triazol-1-yl compound, undesirable 1,2,4-triazol-4-yl isomers are also formed.

[0003] In agricultural chemistry, the active desired 1,2,4-triazole-1-yl compound components must be provided in high purity in order to ensure high product reliability and avoid unexpected and undesirable side effects caused by by-products or other impurities. In addition, yield losses must be minimized.

[0004] WO 2017 / 102905 describes a method for producing 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol in high purity. According to this method, the product is purified by crystallization. However, crystallization causes some product loss to the filtrate. Therefore, the filtrate contains the desired 1,2,4-triazol-1-yl compound and almost all of the undesirable 1,2,4-triazol-4-yl isomers formed.

[0005] Surprisingly, we have found that the undesired 1,2,4-triazol-4-yl isomer can be purified from the filtrate by precipitating it and then separating it from the mother liquor. Thereafter, the mother liquor enriched with the desired product is returned to the process. In this way, more than 90% of the product lost to the mother liquor after crystallization can be recovered and reintroduced into the process while maintaining the desired high purity of the final product. Furthermore, in this way, the amount of aromatic solvent used for crystallization can be reduced.

[0006] It is therefore an object of the present invention to provide a process which produces 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol in high purity, minimizing the loss of the desired 1,2,4-triazol-1-yl compound during purification and reducing the amount of aromatic solvent used in the process.

[0007] Therefore, the present invention relates to a method for obtaining the compound of formula (I) from a mixture containing 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol of formula (I) and 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-4-yl)propan-2-ol of formula (I-sym),

[0008]

[0009] The method includes

[0010] (a) providing a mixture containing compounds of formula (I) and (I-sym) in at least one aromatic solvent, wherein the mixture contains the compound of formula (I) in a concentration of 30% to 90% by weight relative to the total weight of the mixture;

[0011] (b) adding at least one polar aprotic solvent to the mixture of step (a) such that the content of the at least one polar aprotic solvent is from 1% to 25% by weight relative to the weight of the solution obtained after its addition;

[0012] (c) crystallizing a compound of formula (I) from the mixture obtained in step (b);

[0013] (d) adding water in an amount of 10 to 40% by weight relative to the total weight of the mother liquor to the mother liquor obtained after crystallization in step (c); and

[0014] (e) separating a liquid phase from the mixture obtained in step (d) and returning the separated liquid phase to step (a).

[0015] When compound (I) is prepared by nucleophilic addition of 1H-[1,2,4]-triazole to an electrophilic carbon atom of a precursor molecule of compound (I) or by substitution of 1H-[1,2,4]-triazole at an electrophilic carbon atom of a precursor molecule of compound (I), a mixture containing compound (I) and (I-sym) is generally formed. For example, when 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane is reacted with 1H-[1,2,4]-triazole, such a mixture is generally formed.

[0016] Thus, step (a) may, for example, include the following steps:

[0017] (i) 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane having the formula (II)

[0018]

[0019] reacting with 1H-[1,2,4]-triazole in the presence of a base in at least one polar aprotic solvent;

[0020] (ii) removing at least 90% of the at least one polar aprotic solvent after the reaction is complete;

[0021] (iii) diluting the mixture obtained in step (ii) with at least one aromatic solvent and extracting the diluted mixture with water or an aqueous solution;

[0022] (iv) adjusting the amount of the aromatic solvent in the organic phase obtained in step (iii) to such an extent that the resulting mixture contains the compound (I) in a concentration of 30 to 90% by weight relative to the total weight of the mixture.

[0023] Therefore, in one aspect, the present invention relates to a method for obtaining a compound of formula (I) from a mixture containing 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol of formula (I) and 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-4-yl)propan-2-ol of formula (I-sym),

[0024]

[0025] The method includes

[0026] (a) providing a mixture comprising compounds of formula (I) and (I-sym) in at least one aromatic solvent, wherein the mixture contains a concentration of 30% to 90% by weight of the compound of formula (I) relative to the total weight of the mixture, wherein the mixture is provided by:

[0027] (i) 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane having the formula (II)

[0028]

[0029] reacting with 1H-[1,2,4]-triazole in the presence of a base in at least one polar aprotic solvent;

[0030] (ii) removing at least 90% of the at least one polar aprotic solvent after the reaction is complete;

[0031] (iii) diluting the mixture obtained in step (ii) with at least one aromatic solvent and extracting the diluted mixture with water or an aqueous solution;

[0032] (iv) adjusting the amount of the aromatic solvent in the organic phase obtained in step (iii) to such an extent that the resulting mixture contains the compound (I) in a concentration of 30 to 90% by weight relative to the total weight of the mixture.

[0033] (b) adding at least one polar aprotic solvent to the mixture of step (a) such that the content of the at least one polar aprotic solvent is from 1% to 25% by weight relative to the weight of the solution obtained after its addition;

[0034] (c) crystallizing a compound of formula (I) from the mixture obtained in step (b);

[0035] (d) adding water in an amount of 10 to 40% by weight relative to the total weight of the mother liquor to the mother liquor obtained after crystallization in step (c); and

[0036] (e) separating a liquid phase from the mixture obtained in step (d) and returning the separated liquid phase to step (a)(iii).

[0037] In addition to compounds (I) and (I-sym) and at least one aromatic solvent, the mixture provided in step (a) may contain impurities, such as unreacted starting materials from which compounds (I) and (I-sym) are formed. It may also contain trace amounts of other organic solvents (i.e., solvents different from the one or more aromatic solvents used in step (a)). However, the content of these impurities and other organic solvents (if present) is relatively small, and their total amount is preferably at most 15% by weight, more preferably at most 10% by weight, and in particular at most 5% by weight, relative to the total weight of the mixture. In particular, the content of other organic solvents (if present) is at most 10% by weight, preferably at most 8% by weight, in particular at most 5% by weight, and in particular at most 2% by weight, relative to the total weight of the mixture.

[0038] In step (a)(i), 1H-[1,2,4]-triazole is preferably used in at least an equimolar amount relative to ethylene oxide (II). Preferably, ethylene oxide (II) and 1H-[1,2,4]-triazole are used in a molar ratio of 1:1 to 1:4, more preferably 1:1 to 1:3, in particular 1:1.1 to 1:2, more particularly 1:1.1 to 1:1.5 and especially 1:1.1 to 1:1.35.

[0039] The base used in step (a) (i) can be an inorganic base or an organic base. Inorganic bases are, for example, hydroxides, carbonates, bicarbonates, phosphates and hydrogen phosphates of alkali metals and alkaline earth metals. Organic bases are, for example, pyridine, substituted pyridines such as lutidine or 4-(dimethylamino)-pyridine, tertiary amines such as triethylamine, tripropylamine, diisopropylethylamine or morpholine, or cyclic amidines such as 1,4-diazabicyclo [2.2.2] octane (DABCO), 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) or 1,5-diazabicyclo (4.3.0) non-5-ene (DBN).

[0040] Preferably, however, an inorganic base is used. Preferred inorganic bases are alkali metal hydroxides, carbonates and phosphates, in particular LiOH, NaOH, KOH, Li 2 CO 3 、Na 2 CO 3 , K 2 CO 3 , Cs 2 CO 3 , Li 3 PO 4 、Na 3 PO 4 or K 3 PO 4 In particular, alkali metal hydroxides are used, and in particular NaOH or KOH. Very particularly, NaOH is used.

[0041] In a specific embodiment, at least a portion of the 1H-[1,2,4]-triazole is in the form of its corresponding alkali metal salt, such as Li + 、Na + or K + This is obtained by reacting 1H-[1,2,4]-triazole with the corresponding hydroxide (i.e. LiOH, NaOH or KOH), hydride (LiH or NaH) or alcoholate (e.g. sodium or potassium methoxide, sodium or potassium ethoxide or sodium or potassium tert-butoxide) and isolating it before introducing it into the reaction of step (a)(i).

[0042] Strong base (i.e. pK b Bases with an R (ratio) of less than 3.75 are preferably used in at most stoichiometric amounts relative to ethylene oxide (II). In the case of bases derived from polybasic acids such as carbonates and phosphates, and in the case of bases derived from monobasic acids but with doubly or triply charged counter cations such as alkaline earth metal hydroxides (e.g. Ca(OH) 2), the term "stoichiometric" of course takes into account how many protons the base can neutralize. For example, in the case of alkali metal hydroxides, the stoichiometric amount relative to ethylene oxide (II) means a molar ratio of 1:1, while in the case of alkali metal or alkaline earth metal carbonates or alkaline earth metal hydroxides, the stoichiometric amount relative to ethylene oxide (II) means a molar ratio of ethylene oxide to base of 2:1, and in the case of alkali metal phosphates, the stoichiometric amount relative to ethylene oxide (II) means a molar ratio of ethylene oxide to phosphate of 3:1.

[0043] Weaker bases (i.e., pK b The bases with a molar ratio of at least 3.75 are preferably used in at least a stoichiometric amount. For the "stoichiometric amount" in the case of bases derived from polyacids, the above statements apply.

[0044] In the case of bases derived from strong monobasic acids and having a monovalent countercation, here alkali metal hydroxides, the base is preferably used in an amount of 0.2 to 1 mol / mol ethylene oxide (II), in particular 0.3 to 0.7 mol / mol ethylene oxide (II).

[0045] Step (a)(i) is generally carried out at 100° C. to the boiling point of the reaction mixture. However, it has been found that if the reaction in step (a)(i) is carried out at 110° C. to 130° C., in particular 110° C. to 120° C. and especially 110° C. to 115° C., the compound of formula (I) is obtained in higher purity.

[0046] Aprotic solvents are solvents without functional groups that can dissociate protons. Polar solvents are solvents with a dielectric constant greater than 15. Polar aprotic solvents combine two properties. Examples of polar aprotic solvents are amides, such as N,N-dimethylformamide (DMF) and N,N-dimethylacetamide; sulfoxides, such as dimethyl sulfoxide (DMSO); lactams, such as N-methylpyrrolidone (NMP); cyclic ethers, such as tetrahydrofuran, 1,3-dioxane and 1,4-dioxane; ketones, such as acetone and methyl ethyl ketone; nitriles, such as acetonitrile; lactones, such as γ-butyrolactone; nitro compounds, such as nitromethane; ureas, such as tetramethylurea or dimethylpropyleneurea (DMPU); sulfones, such as sulfolane; and carbonic acids, such as dimethyl carbonate or ethylene carbonate.

[0047] At least one polar aprotic solvent used in steps (a)(i) and (b) may be the same or different. It is independently selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, tetrahydrofuran, 1,4-dioxane, acetone, methyl ethyl ketone, acetonitrile and mixtures thereof; preferably, it is independently selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone; more preferably, it is N,N-dimethylformamide.

[0048] In step (a)(ii), after completion of the reaction, all or at least substantially all of the one or more polar aprotic solvents, i.e. at least 90%, preferably at least 92%, in particular at least 95% and especially at least 98%, of the one or more polar aprotic solvents are removed. These percentages are relative to the amount of the one or more solvents introduced in step (a)(i), which is considered to be 100%.

[0049] Preferably, the one or more polar aprotic solvents are removed to such an extent that the weight ratio of the one or more polar aprotic solvents remaining in the resulting mixture to the theoretically present compound (I) (i.e. if the yield is 100%) is at most 1:3, i.e. 1:3 to 0:1; more preferably at most 1:4, i.e. 1:4 to 0:1; in particular at most 1:7, i.e. 1:7 to 0:1; more particularly at most 1:9, i.e. 1:9 to 0:1; even more particularly at most 1:19, i.e. 1:19 to 0:1; and especially at most 1:24, i.e. 1:24 to 0:1. The one or more solvents are usually removed by distillation.

[0050] The temperature used for the distillation preferably does not exceed the reaction temperature of step (a)(i). Therefore, the distillation is preferably carried out under reduced pressure. The amount of the one or more solvents removed can be determined, for example, by weighing the amount of the one or more solvents removed and comparing it with the amount introduced in step (a)(i), or by gas chromatography of the reaction mixture obtained after removal of the one or more solvents.

[0051] "Completion of reaction" means that the reaction is carried out until no more ethylene oxide (II) can be detected. Detection can be accomplished by standard methods, such as TLC, GC, HPLC or NMR of a sample of the reaction mixture.

[0052] In step (a)(iii), the mixture obtained in step (a)(ii) is diluted with at least one aromatic solvent and the diluted mixture is extracted with an aqueous medium, i.e. water or an aqueous solution. The aqueous extraction is carried out in order to remove any salt formed (if present), excess base (if present), excess 1H-[1,2,4]-triazole (if present), residues of one or more polar aprotic solvents (if present) and any other water-soluble components (if present). At least one aromatic solvent may be added first to the mixture obtained in step (a)(ii) and water or an aqueous solution may be added subsequently, or vice versa, or at least one aromatic solvent and water or an aqueous solution may be added simultaneously.

[0053] The at least one aromatic solvent used in step (a)(iii) is preferably selected from benzene, toluene, xylenes and mixtures thereof; and in particular toluene.

[0054] The aqueous solution is, for example, brine (saturated aqueous sodium chloride solution), unsaturated aqueous sodium chloride solution or an acidic solution (eg dilute aqueous HCl solution).

[0055] Preferably, the extractant is water or brine and in particular water.

[0056] In a preferred embodiment, the extraction in step (a)(iii) is carried out at 50° C. to 90° C., in particular 70° C. to 90° C. The heating is mainly carried out in order to improve the dissolution of the components of the mixture of step (a)(ii) in one of the two solvent systems (aromatic solvent or aqueous medium).

[0057] After extraction, ie, after the organic phase and the aqueous phase are brought into intimate contact with each other, the aqueous phase and the organic phase are separated.

[0058] In step (a)(iv) (if necessary), a portion of the one or more aromatic solvents introduced in step (a)(iii) is removed from the organic phase obtained in step (a)(iii) to such an extent that the resulting mixture contains compound (I) in a concentration of 30 to 90% by weight relative to the total weight of the resulting mixture (i.e. the mixture obtained after removal of the one or more aromatic solvents).

[0059] Step (a)(iv) is necessary if the amount of the aromatic solvent(s) introduced in step (a)(iii) is so high that the mixture obtained after step (a)(iii) contains compound (I) in a concentration of less than 30% by weight relative to the total weight of the mixture.

[0060] Preferably, the at least one aromatic compound is removed to such an extent that the resulting mixture contains a concentration of compound (I) ranging from 40% to 65% by weight relative to the total weight of the mixture.

[0061] The concentration of compound (I) in the mixture is determined by standard procedures, for example by gas chromatography or HPLC.

[0062] Similarly, the mixture of step (a) preferably contains compound (I) in a concentration ranging from 40% to 65% by weight relative to the total weight of the mixture.

[0063] In step (b), at least one polar aprotic solvent is added to the mixture of step (a) in such an amount that the content of the at least one polar aprotic solvent is 1 to 25% by weight, preferably 2 to 15% by weight, more preferably 2 to 12% by weight, in particular 2 to 9% by weight, especially 2 to 8% by weight and very especially 3 to 8% by weight, relative to the weight of the mixture obtained after its addition.

[0064] If the mixture of step (a) contains solids visible to the naked eye, it is preferred to heat this mixture before adding the at least one polar aprotic solvent to obtain a mixture without visible solids. Preferably, the mixture is heated to 50° C. to 100° C., in particular 70° C. to 90° C., before adding the at least one polar aprotic solvent.

[0065] The crystallization in step (c) is carried out by known methods, for example by simply allowing the mixture to stand; or by cooling the mixture, especially if it has been heated before; or by heating and cooling again, or by reheating the cooled mixture and cooling it again. Cooling and heating can be repeated several times. Seed crystals of a compound of formula (I) can be added to the cooled solution in order to induce crystallization.

[0066] In particular, the crystallization in step (c) is performed by cooling the preheated mixture of step (b) and optionally adding seed crystals; or, alternatively, by cooling the preheated mixture of step (b), reheating and cooling again.

[0067] Cooling generally means cooling to room temperature or lower, preferably cooling to +10°C to -10°C, particularly cooling to +5°C to -5°C and especially cooling to 0°C. Cooling is generally carried out within 1 to 12 h, preferably within 2 to 10 h, particularly within 6 to 10 h. Cooling can be carried out continuously or stepwise (ie with several temperature gradients).

[0068] The crystals formed are recovered from the mother liquor by standard methods, for example by filtration, sedimentation, decantation or centrifugation. If desired, the crystals are freed from solvent residues, for example by washing with water and / or evaporation, especially under vacuum.

[0069] In step (d), the amount of water added to the mother liquor obtained in step (c) is usually 10 to 40% by weight relative to the total weight of the mother liquor.

[0070] In a preferred embodiment, water is gradually (e.g. dropwise or in several portions) added to the mother liquor. Preferably, the addition of water is carried out over a period of 0.5 h to 5 h, more preferably over a period of 1 h to 4.5 h, most preferably over a period of 2 h to 4 h.

[0071] During the addition of water to the mother liquor in step (d), the mixture is preferably stirred.

[0072] The temperature of the mixture in step (d) is preferably maintained at 20 to 50° C., more preferably 25 to 45° C., most preferably 25 to 35° C. According to a specific embodiment, the mixture is kept isothermal during the addition of water.

[0073] In step (e), the solid formed is separated from the mother liquor by standard methods (eg by filtration, sedimentation, decantation or centrifugation).The liquid phase is collected and returned to step (a) or (a)(iii).

[0074] In steps d) and e), up to 95% of the compound of formula (I-sym) can be removed as a solid, while up to 95% of the compound of formula (I) lost to the mother liquor from step (c) remains in the liquid phase and can then be directly recycled back into the process. This recycling helps to reduce the amount of aromatic solvent used in step (a) and the amount of polar aprotic solvent used in step (b).

[0075] The process of the present invention produces the desired 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol in a purity of at least 98%, particularly at least 98.5%, more particularly at least 99%.

[0076] Examples

[0077] Example 1

[0078] Preparation of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol (without recycling mother liquor)

[0079] 243.6 g (0.740 mol) of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane, 56.37 g (0.816 mol) of 1H-[1,2,4]-triazole, 15.75 g (0.393 mol) of NaOH (flakes) and 593 g of DMF were charged into a 1.0 1 laboratory vessel at room temperature. The mixture was heated to 115° C. over 12 h to completely convert the oxirane starting material (yield of the desired isomer: 92% in solution).

[0080] Then, DMF (>95%) was almost completely removed from the reaction mixture by vacuum distillation. Salts and remaining DMF were separated from the product by extraction with 727 g toluene and 447 g water at 80° C. Finally, 559 g (77%) of toluene were removed from the product by concentrating the organic phase under vacuum.

[0081] At 85°C, DMF for crystallization is added to the product solution in toluene. The amount of DMF is calculated to obtain a final concentration of 6% in the pre-crystallization solution. Then, the solution in toluene / DMF is cooled to about 70°C, inoculated with the title product and stirred for 0.5h. The suspension is slowly cooled to 10°C over 8h to crystallize the product. The product is separated from the mother liquor by centrifugation and dried in a vacuum oven at 80°C / 30 mbar. The dried product is weighed and analyzed for purity. The reaction yield is then calculated and summarized in Table 1 (Examples 1.1 to 1.7).

[0082] Example 2

[0083] Preparation of 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol (with recycling of mother liquor)

[0084] The procedure according to Example 1 was repeated.

[0085] To 509.8 g of the mother liquor plus the wash liquor resulting from the above crystallization process (6.3% of product I and 4.9% of product I-sym) was added 102 g of water over 3 hours while stirring and maintaining the mixture at 25°C. The mixture was then filtered to remove solids, which were primarily (88% concentration after drying) product I-sym. The two-phase filtrate (570 g) was collected for use as a recycle as outlined below.

[0086] Starting with 745 g of product I (31.0%) and product I-sym (3.13%) in N,N-dimethylformamide, 427.6 g of polar aprotic solvent were removed by vacuum distillation.

[0087] The above biphasic filtrate (570 g) was added to the remaining distillation bottoms along with 249.5 g fresh toluene and 295.0 g fresh water. The mixture was held at 80°C for 30 minutes and the phases were allowed to separate. 420.5 g of the aqueous phase was removed and 992.4 g of the organic phase was retained for the next step.

[0088] 475.2 g of solvent (mainly toluene) were removed by distillation under vacuum, yielding a solution containing 51.528% of the product I. NN-dimethylformamide was then added so that the concentration of this polar aprotic solvent was 6.97%.

[0089] The solution was then slowly cooled to 75°C, seeded with product, and then cooled to 60°C over 2 hours, 20°C over 3 hours, and 10°C over 1 hour, and the slurry was held at temperature for an additional 30 minutes.

[0090] The slurry was then filtered and the wet cake was washed with toluene. The wet cake was dried and analyzed. The reaction yields were then calculated and summarized in Table 2 (Examples 2.1 to 2.9).

[0091]

[0092]

Claims

1. A method for obtaining a compound of formula (I) from a mixture containing 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-1-yl)propan-2-ol of formula (I) and 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-1-(1,2,4-triazol-4-yl)propan-2-ol of formula (I-sym), The method includes (a) providing a mixture containing the compounds of formula (I) and (I-sym) in at least one aromatic solvent, wherein the mixture contains the compound of formula (I) in a concentration of 30% to 90% by weight relative to the total weight of the mixture; (b) adding at least one polar aprotic solvent to the mixture of step (a) such that the content of the at least one polar aprotic solvent is from 1% to 25% by weight relative to the weight of the solution obtained after its addition; (c) crystallizing the compound of formula (I) from the mixture obtained in step (b); (d) adding water in an amount of 10 to 40% by weight relative to the total weight of the mother liquor to the mother liquor obtained after crystallization in step (c); and (e) separating a liquid phase from the mixture obtained in step (d) and returning the separated liquid phase to step (a).

2. The method of claim 1, wherein: Step a) comprises the following steps: (i) 2-[4-(4-chlorophenoxy)-2-(trifluoromethyl)phenyl]-2-methyl-oxirane having the formula (II) reacting with 1H-[1,2,4]-triazole in the presence of a base in at least one polar aprotic solvent; (ii) after completion of the reaction, removing at least 90% of the at least one polar aprotic solvent; (iii) diluting the mixture obtained in step (ii) with at least one aromatic solvent and extracting the diluted mixture with water or an aqueous solution; (iv) adjusting the amount of the aromatic solvent in the organic phase obtained in step (iii) to such an extent that the resulting mixture contains the compound (I) in a concentration of 30 to 90% by weight relative to the total weight of the mixture.

3. The method according to claim 1 or 2, wherein: The at least one aromatic solvent used in step (a) is selected from benzene, toluene, xylenes and mixtures thereof; and in particular toluene.

4. The method according to any one of claims 1 to 3, wherein: The at least one polar aprotic solvent used in step (b) is selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

5. The method according to any one of claims 1 to 4, wherein: The at least one polar aprotic solvent used in step (b) is N,N-dimethylformamide.

6. The method according to any one of claims 1 to 5, wherein: The water in step (d) is added gradually.

7. The method according to any one of claims 1 to 7, wherein: The temperature in step (d) is 20°C to 50°C.

Images