Method for synthesizing propiconazole by using ionic liquid catalyst

Abstract

The application belongs to the field of chemical production, and particularly relates to a method for synthesizing propiconazole by catalysis of ionic liquid. Condensation reaction is carried out between bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and triazole under catalysis of ionic liquid to generate propiconazole. The ionic liquid is one of [Emim]BF4, [Emim]PF6, [BMIM]PF6 and [BMIM]OH. In the application, the ionic liquid of imidazole cation is used as a catalyst and a solvent, and N-alkylation reaction is carried out between 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and triazole. It is found that the basic ionic liquid of imidazole cation has good catalytic performance, high yield and good selectivity, and the reaction condition is mild, the operation is simple, the ionic liquid is easy to recover, and the catalytic activity is not obviously reduced after five times of recycling.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of chemical production, and particularly relates to a method for synthesizing propiconazole by using ionic liquid as a catalyst. BACKGROUND

[0002] Propiconazole is an endosporal triazole fungicide with the functions of protection and treatment, and can effectively prevent and treat diseases caused by most higher fungi. Propiconazole has the characteristics of wide fungicidal spectrum, high activity, fast fungicidal speed, long persistence, strong endosporal transmission, etc., has become a representative variety of a new broad-spectrum fungicide with large tonnage in the world, and is a special fungicide for economic crops. Propiconazole belongs to the triazole fungicide in sterol inhibitors, and its mechanism of action is to affect the biosynthesis of sterol, so that the cell membrane function of pathogenic bacteria is damaged, and finally the cell death is caused, thereby achieving the effects of fungicidal, disease prevention and treatment.

[0003] At present, the process mainly uses intermediates 2,4-dichloroacetophenone, pentanediol, bromine, triazole, etc. as main raw materials, and high-purity finished products are obtained through cyclization, bromination, condensation, high-vacuum rectification or salt purification, a total of four steps, the total yield is about 70%, the technical grade is 95%, and the product is a yellowish viscous liquid.

[0004] At present, the existing production method has the following disadvantages: 1) the reaction time is long when synthesizing triazole salt, the material is sticky, and it is difficult to dehydrate; 2) the condensation reaction time is long, the by-product cannot be recovered after water washing, and a large amount of wastewater is generated; 3) the reaction condition is harsh, and the product separation is complex. Therefore, it is necessary to establish an effective and environmentally friendly synthesis method.

[0005] Chinese patent CN 113444077 A discloses a production method of propiconazole technical grade, which adopts 2,4-dichloroacetophenone and 1,2-pentanediol for cyclization, then generates 2-bromomethyl-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane by bromination reaction with bromine, and then generates propiconazole by condensation reaction with 1,2,4-triazole in a solvent, alkali and phase transfer catalyst. The method for producing propiconazole uses organic solvent, which is polluting; alkali is added in the condensation reaction process, and the subsequent process needs to recover by-products, which is complex.

[0006] Ionic liquid refers to a salt composed of organic cation and inorganic anion or organic anion, which is in liquid state at room temperature or near room temperature, and is also called room temperature molten salt. Compared with traditional solvents, ionic liquid has many excellent properties, is considered as a green solvent that can replace volatile organic solvents in many fields; common cations include quaternary ammonium salt ions, quaternary phosphonium salt ions, imidazole salt ions, pyridine salt ions, etc.; anions include halogen ions, tetrafluoroborate ions, hexafluorophosphate ions, etc.; compared with traditional organic solvents, ionic liquid has the following advantages:

[0007] 1) Good solubility for inorganic, organic, and some polymers;

[0008] 2) Room temperature ionic liquids are usually liquid in the range of 300℃;

[0009] 3) Almost no vapor pressure, non-volatile;

[0010] 4) Convenient recycling;

[0011] 5) Ionic liquids have variable Lewis / Bronsted acidity and basicity, and a wide pH adjustment range;

[0012] There are reports that basic ionic liquid [BMIM]OH (1-butyl-3-methylimidazole hydroxide) is applied to Knoevenagel condensation, Markovnikov and Michael addition, Mannich addition and Perkin reaction. However, there is no report on the reaction of using ionic liquid as a catalyst to synthesize propiconazole. SUMMARY

[0013] The technical problem to be solved by the present application is that the current process uses organic toxic solvents and catalysts, has high reaction temperature, harsh reaction conditions, long reaction time, and difficult product separation. In the process of synthesizing propiconazole, ionic liquid is used as a solvent and a catalyst, which improves the reaction rate, makes the reaction conditions more mild, is simple to operate, has high reaction yield, and reduces production cost.

[0014] In order to realize the ionic liquid catalytic synthesis of propiconazole, the present application adopts the following scheme: the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is subjected to condensation reaction with triazole under the catalysis of ionic liquid to generate propiconazole.

[0015] Further, the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is subjected to condensation reaction with triazole under the catalysis of ionic liquid in the presence of water to generate propiconazole.

[0016] In the condensation reaction, the ionic liquid is one of [Emim]BF4, [Emim]PF6, [BMIM]PF6, and [BMIM]OH, and the molar ratio of the ionic liquid to 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is 0.2:1-0.8:1.

[0017] Further, the molar ratio of the ionic liquid to 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is 0.2:1-0.4:1

[0018] The molar ratio of the triazole to the 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane in the condensation reaction is 0.90-1.10:1.

[0019] Further, the molar ratio of the triazole to the 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane in the condensation reaction is 0.98-1.02:1.

[0020] The condensation reaction temperature is 80-100℃.

[0021] The preparation method of the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is as follows: 2,4-dichloroacetophenone and 1,2-pentanediol are used as raw materials, a cyclization reaction is carried out in the presence of a solvent A and a solid acid catalyst to generate a cyclization product, and the cyclization product is subjected to a bromination reaction with bromine to generate the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane.

[0022] Further, the specific steps are as follows:

[0023] (1) The cyclization reaction: 2,4-dichloroacetophenone and 1,2-pentanediol are subjected to a cyclization reaction under heating and reflux in the presence of a solvent A and a solid acid catalyst, after the reaction is completed, the solid acid catalyst is recovered after cooling, and a filtrate containing 2-methyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is obtained;

[0024]

[0025] (2) The bromination reaction: bromine is added dropwise into the filtrate containing the cyclization product to carry out a bromination reaction, after the reaction is completed, the reaction solution is subjected to alkaline washing and simple distillation of the solvent A, and the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is obtained;

[0026]

[0027] (3) The condensation reaction: the bromide 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is subjected to a condensation reaction with the triazole in the presence of water, the reaction is carried out under heating to 80-100℃ by using an ionic liquid as a catalyst, after the reaction is completed, the reaction solution is extracted with a solvent B, and the propiconazole is obtained after simple distillation of the solvent B.

[0028]

[0029] The solid acid catalyst is one of phosphomolybdic acid, phosphotungstic acid and p-toluenesulfonic acid.

[0030] The solid acid catalyst obtained after the reaction is completed is recovered after being washed with water.

[0031] The solvent A is one or more of benzene, toluene or cyclohexane; the solvent B is one or more of dichloromethane, dichloroethane, chloroform, tetrahydrofuran.

[0032] In the cyclization reaction, the molar ratio of 2,4-dichloroacetophenone, 1,2-pentanediol and solid acid catalyst is 1:1.05-1.20:0.02-0.04.

[0033] In the bromination reaction, the molar ratio of bromine and 2,4-dichloroacetophenone is 1:1-1.5:1; the bromination reaction temperature is 20-40℃.

[0034] The present application uses imidazole cation ionic liquid as catalyst and solvent to catalyze N-alkylation reaction of 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and triazole. It is found that the basic imidazole cation ionic liquid has good catalytic performance, high yield and good selectivity, and the reaction conditions are mild, the operation is simple, the ionic liquid is easy to recover, and the catalytic activity is not obviously reduced after five times of reuse. Compared with the existing propiconazole synthesis process, the present application has the following advantages:

[0035] 1) The ionic liquid used in the present application has high catalytic activity and good selectivity;

[0036] 2) The basic ionic liquid used in the present application is liquid at room temperature, has good solubility for reaction raw materials, does not need to add organic solvents during the reaction, and is more green and environmentally friendly;

[0037] 3) The ionic liquid used in the present application has low vapor pressure and good thermal stability, and after the reaction is completed, the ionic liquid catalyst can be recycled after simple distillation or extraction separation of the product. DETAILED DESCRIPTION

[0038] The specific implementation of the technical scheme of the present application is described in detail in combination with the following examples:

[0039] Examples 1 and 2 are the synthesis of bromide, and two reactions of cyclization reaction and bromination reaction are specifically required, and the reaction equation is as follows:

[0040] Cyclization reaction:

[0041]

[0042] Bromination reaction:

[0043]

[0044] Example 1:

[0045] (1) Cyclization reaction: 500ml four-port bottle was put into 138.5g cyclohexane, 100g 2,4-dichloroacetophenone, 59.5g 1,2-pentanediol, 2.4g p-toluenesulfonic acid was added, stirring, heating to reflux reaction, sample chromatographic analysis of 2,4-dichloroacetophenone <1.0%, stop reaction; the reaction solution was cooled to room temperature, the solid acid was recovered by filtration, and the obtained filtrate was subjected to the next step reaction;

[0046] (2) Bromination reaction: the filtrate obtained by cyclization reaction was added dropwise with 85g bromine at 20-40°C, sample chromatographic analysis of 2-methyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane <1.0% during the dropwise addition process, stop reaction; the reaction solution was washed with 24% KOH solution to remove the generated HBr, and the washing was continued until pH≥12, the remaining material was subjected to simple evaporation under negative pressure with a rotary evaporator to remove the cyclohexane solvent, and 185g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane was obtained, with a content of 96.4% and a yield of 95.22%.

[0047] Example 2:

[0048] (1) Cyclization reaction: 500ml four-port bottle was put into 138.5g cyclohexane, 100g 2,4-dichloroacetophenone, 59.5g 1,2-pentanediol, 2.4g p-toluenesulfonic acid was added, stirring, heating to reflux reaction, sample chromatographic analysis of 2,4-dichloroacetophenone <1.0%, stop reaction; the reaction solution was cooled to room temperature, the solid acid was recovered by filtration, and the obtained filtrate was subjected to the next step reaction;

[0049] (2) Bromination reaction: the filtrate obtained by cyclization reaction was added dropwise with 86g bromine at 20-40°C, sample chromatographic analysis of 2-methyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane <1.0% during the dropwise addition process, stop reaction; the reaction solution was washed with 24% KOH solution to remove the generated HBr, and the washing was continued until pH≥12, the remaining material was subjected to simple evaporation under negative pressure with a rotary evaporator to remove the cyclohexane solvent, and 186g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane was obtained, with a content of 97.0% and a yield of 96.33%.

[0050] Examples 3-12 are condensation synthesis, mainly exploring the influence of different types of catalysts on the reaction, and the reaction equation is as follows:

[0051] Condensation reaction

[0052]

[0053] Example 3:

[0054] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g triazole, 5.92g KOH, 17.76g water is added, stirring to 80℃ for 4hr, the reaction solution is extracted with 360g dichloroethane three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 183.5g residue, the content of propiconazole in the residue is 11.20%, the yield is 11.36%;

[0055] Example 4:

[0056] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g triazole, 12.92g N,N-dimethylpyridine, 38.77g water is added, stirring to 80℃ for 4hr, the reaction solution is extracted with 360g dichloroethane three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 182.4g residue, the content of propiconazole in the residue is 0.48%, basically no reaction;

[0057] Example 5:

[0058] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g triazole, 17.61g tetraethylammonium chloride, 52.82g water is added, stirring to 80℃ for 4hr, the reaction solution is extracted with 360g dichloroethane three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 186.4g residue, the content of propiconazole in the residue is 0.15%, basically no reaction;

[0059] Example 6:

[0060] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g triazole, 34.09g tetrabutylammonium bromide, 102.27g water is added, stirring to 80℃ for 4hr, the reaction solution is extracted with 360g dichloroethane three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 184.2g residue, the content of propiconazole in the residue is 0.89%, basically no reaction;

[0061] Example 7:

[0062] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, 18.54g [BMIM]Cl, 55.63g water is added, stirring to 80°C reaction 4hr, the reaction liquid is added 360g dichloroethane extraction three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 182.4g remaining material, the remaining material propiconazole content 18.4%, yield 18.55%;

[0063] Example 8:

[0064] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, 18.54g [BMIM]Cl, 55.63g water is added, stirring to 80°C reaction 4hr, the reaction liquid is added 360g dichloroethane extraction three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 182.4g remaining material, the remaining material propiconazole content 18.4%, yield 18.55%;

[0065] Example 9:

[0066] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, 23.23g [BMIM]Br, 69.68g water is added, stirring to 80°C reaction 4hr, the reaction liquid is added 360g dichloroethane extraction three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 181.4g remaining material, the remaining material propiconazole content 20.4%, yield 20.45%;

[0067] Example 10:

[0068] 1000ml four-mouth bottle is put into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, 16.48g [BMIM]OH, 49.45g water is added, stirring to 80°C reaction 4hr, the reaction liquid is added 360g dichloroethane extraction three times, combined extract, dichloroethane is evaporated by rotary evaporator under negative pressure, 186.5g remaining material, the remaining material propiconazole content 94.05%, yield 96.95%;

[0069] Example 11:

[0070] 1000ml four-port bottle into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, add 29.97g [BMIM]PF6, 89.90g water, stirring to 80°C for 4hr, the reaction liquid plus 360g dichloroethane extraction three times, combined extract, dichloroethane with a rotary evaporator negative pressure simple steam, get 182.4g residue, the residue propiconazole content 46.14%, yield 46.52%;

[0071] Example 12:

[0072] 1000ml four-port bottle into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, add 20.98g [Emim]BF4, 62.93g water, stirring to 80°C for 4hr, the reaction liquid plus 360g dichloroethane extraction three times, combined extract, dichloroethane with a rotary evaporator negative pressure simple steam, get 182.4g residue, the residue propiconazole content 48.42%, yield 48.82%;

[0073] From the above experiments, the influence of different catalysts on the reaction activity and yield as shown in Table 1:

[0074] Table 1: the reaction of different catalysts in examples 3-12

[0075]

[0076] From the results, the basic ionic liquid [BMIM]OH has the highest catalytic activity for N-alkylation of 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and triazole, and the highest yield. Inorganic ionic liquid and slightly acidic and neutral ionic liquid have lower or almost no catalytic activity for the reaction.

[0077] Examples 13-16 are exploratory experiments of the influence of catalyst amount on the reaction during the synthesis of propiconazole:

[0078] Example 13:

[0079] 1000ml four-port bottle into 187.3g 2-bromomethyl-2-(2,4-dichlorophenyl)-4- propyl-1,3-dioxolane, 36.5g triazole, add 8.25g [BMIM]OH, 24.75g water, stirring to 80°C for 4hr, the reaction liquid plus 360g dichloroethane extraction three times, combined extract, dichloroethane with a rotary evaporator negative pressure simple steam, get 182.4g residue, the residue propiconazole content 62.14%, reaction yield 62.65%;

[0080] Example 14:

[0081] Into a 1000ml four-necked flask, 187.3g of 2-bromomethyl-2-(2,4- dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g of triazole, 16.50g of [BMIM]OH, 49.50g of water were added, and stirred to 80°C for 4 hours. The reaction solution was extracted with 360g of dichloroethane for three times, and the combined extract was evaporated under negative pressure to obtain 186.0g of residue, in which the content of propiconazole was 94.11%, and the reaction yield was 96.75%.

[0082] Example 15:

[0083] Into a 1000ml four-necked flask, 187.3g of 2-bromomethyl-2-(2,4- dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g of triazole, 41.26g of [BMIM]OH, 123.78g of water were added, and stirred to 80°C for 4 hours. The reaction solution was extracted with 360g of dichloroethane for three times, and the combined extract was evaporated under negative pressure to obtain 185.2g of residue, in which the content of propiconazole was 94.13%, and the reaction yield was 96.36%.

[0084] Example 16:

[0085] Into a 1000ml four-necked flask, 187.3g of 2-bromomethyl-2-(2,4- dichlorophenyl)-4-propyl-1,3-dioxolane, 36.5g of triazole, 66.02g of [BMIM]OH, 198.06g of water were added, and stirred to 80°C for 4 hours. The reaction solution was extracted with 360g of dichloroethane for three times, and the combined extract was evaporated under negative pressure to obtain 185.8g of residue, in which the content of propiconazole was 94.24%, and the reaction yield was 96.78%.

[0086] Based on the above experiments, the influence of different catalyst amounts on the reaction activity and yield is shown in Table 2:

[0087] Table 2 Influence of different catalyst amounts on the reaction activity and yield

[0088]

[0089] From the data in Table 2, it can be seen that when the molar ratio of catalyst to bromide is in the range of 0.2-0.8, very good catalytic effect can be achieved.

[0090] Example 17 is an exploratory experiment of the influence of the number of times of using the ionic liquid catalyst on the reaction:

[0091] Example 17:

[0092] 187.3g of 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and 36.5g of triazole were added to a 1000ml four-necked flask. 16.5g of [BMIM]OH and 49.5g of water were added, and the mixture was stirred and heated to 80℃ for 4 hours. The reaction solution was extracted three times with 360g of dichloroethane. The extracts were combined, and the dichloroethane was simply evaporated under negative pressure using a rotary evaporator to obtain 185.9g of residue. The residue contained 94.15% propiconazole, and the reaction yield was 96.74%.

[0093] The raffinate was adjusted to pH 9-11 with 48% potassium hydroxide, and a large amount of water was removed under negative pressure. The temperature was then increased, and the water was removed under air until almost no more vaporization occurred. The solution was cooled and filtered to obtain solid salts. The filtrate was an ionic liquid, which could be reused. Experiments verified that after five applications, the ionic liquid still exhibited good reactivity for this N-alkylation reaction; details are shown in Table 3.

[0094] Table 3. Effects of catalyst recycling on reaction activity and yield.

[0095]

[0096] The above cyclic experiments show that the alkaline ionic liquid catalyst of this application can still achieve a yield of 96.42% after 5 cycles, with virtually no impact on the catalyst's activity.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for synthesizing propiconazole using ionic liquid catalysis, characterized in that, The brominated compound 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane reacts with triazole in the presence of water under the catalysis of an ionic liquid to generate propiconazole. In the condensation reaction, the ionic liquid is [BMIM]OH, and the molar ratio of the ionic liquid to 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxopentane is 0.2:1 to 0.8:

1.

2. The method according to claim 1, characterized in that, In the condensation reaction, the molar ratio of triazole to 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxopentane is 0.90~1.10:

1.

3. The method according to claim 1, characterized in that, The condensation reaction temperature is 80-100℃.

4. The method according to claim 1, characterized in that, The preparation method of the brominated compound 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane is as follows: using 2,4-dichloroacetophenone and 1,2-pentanediol as raw materials, a cyclization reaction is carried out in the presence of solvent A and a solid acid catalyst to generate a cyclized compound. The cyclized compound is then brominated with bromine to generate the brominated compound 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane.

5. The method according to claim 1, characterized in that, The specific steps are as follows: (1) Cyclization reaction: 2,4-dichloroacetophenone and 1,2-pentanediol were cyclized under reflux in the presence of solvent A and solid acid catalyst. After the reaction was completed, the solid acid catalyst was recovered by cooling, and a filtrate containing 2-methyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane was obtained. (2) Bromination reaction: Bromine is added dropwise to the filtrate containing the cyclized compound to carry out the bromination reaction. After the reaction is completed, the reaction solution is washed with alkali and solvent A is briefly evaporated to obtain the bromine 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxopentane. (3) Condensation reaction: The brominated compound 2-bromomethyl-2-(2,4-dichlorophenyl)-4-propyl-1,3-dioxolane and triazole were condensed in the presence of water and catalyzed by an ionic liquid at 80-100℃. After the reaction was completed, the product was extracted with solvent B and the solvent B was briefly evaporated to obtain propiconazole.

6. The method according to claim 5, characterized in that: The solid acid catalyst is one of phosphomolybdic acid, phosphotungstic acid, and p-toluenesulfonic acid.

7. The method according to claim 5, characterized in that: Solvent A is one or more of benzene, toluene, or cyclohexane; solvent B is one or more of dichloromethane, dichloroethane, chloroform, and tetrahydrofuran.

8. The method according to claim 5, characterized in that: In the cyclization reaction, the molar ratio of 2,4-dichloroacetophenone, 1,2-pentanediol, and solid acid catalyst is 1:1.05~1.20:0.02~0.

04.

9. The method according to claim 1, characterized in that: In the bromination reaction, the molar ratio of bromine to 2,4-dichloroacetophenone is 1:1 to 1.5:1; the bromination reaction temperature is 20-40℃.

Images