Continuous preparation method of 3-halogen-5, 5-dimethyl-4, 5-dihydroisoxazole

Abstract

The invention relates to the technical field of C07D261 / 04, in particular to a continuous preparation method of 3-halo-5, 5-dimethyl-4, 5-dihydroisoxazole, which at least comprises the following steps: adding an organic solution of 1, 1-dihaloformaldoxime, an acid-binding agent and isobutene into a tower-type packed reactor, controlling the reaction temperature and the reaction retention time in the tower-type packed reactor for reaction, and separating and purifying to obtain 3-halo-5, 5-dimethyl-4, 5-dihydroisoxazole. And after the reaction is finished, post-treatment is performed to obtain the 3-halogen-5, 5-dimethyl-4, 5-dihydroisoxazole, so that the automatic control continuous production of the 3-halogen-5, 5-dimethyl-4, 5-dihydroisoxazole is realized, the production efficiency and the yield are improved, and the method is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of C07D261 / 04, and in particular to a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole. Background Art

[0002] 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole can be used to prepare fungicides, insecticides or drugs, and is also a key intermediate of isoxazole herbicides. At present, the industrial synthesis of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole adopts an intermittent process, and there is no report of continuous synthesis. Its raw material 1,1-dihaloformaldehyde oxime has tear-inducing properties and is strongly irritating to the skin. For example, a Chinese patent (publication number is CN 117658938 A) discloses a method for preparing a sulfonepyrazol intermediate, in which hydroxylamine hydrochloride and glyoxylic acid react and then react with an acid binding agent, hydrochloric acid, and hypochlorite to obtain dichloroformaldehyde oxime, and then react with an acid binding agent and isobutylene to prepare a sulfonepyrazol intermediate; and a method for synthesizing a sulfonepyrazol intermediate in a continuous flow disclosed in a Chinese patent (publication number is CN 117486821 A) has a product yield of up to 85%, which still needs to be further improved. Therefore, providing a method for producing 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole by continuous reaction is beneficial to reducing manual operation, lowering operation cost, improving workshop working environment and preventing occupational diseases. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, which realizes the automated controlled continuous production of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, improves the production efficiency and yield, and is suitable for industrial production.

[0004] The invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, which comprises at least the following steps: adding an organic solution of 1,1-dihalogen formaldehyde oxime, an acid binding agent and isobutylene into a tower packing reactor, controlling the reaction temperature and the reaction residence time in the tower packing reactor to carry out a reaction, and after the reaction is completed, carrying out a post-treatment to obtain 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole.

[0005] As a preferred technical solution, the continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole at least comprises the following steps: an organic solution of 1,1-dihaloformaldehyde oxime and an acid binding agent are introduced into a tower packing reactor through a T-type mixer outside the tower, and isobutylene is introduced into the tower packing reactor from the bottom of the tower packing reactor, the reaction temperature and the reaction residence time in the tower packing reactor are controlled to react, and after the reaction is completed, 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole is obtained by post-treatment.

[0006] As a preferred technical solution, the organic solution of 1,1-dihaloformaldehyde oxime comprises 1,1-dihaloformaldehyde oxime and an organic solvent, and the mass concentration of 1,1-dihaloformaldehyde oxime in the organic solution of 1,1-dihaloformaldehyde oxime is 15-40%, preferably 20-40%.

[0007] Preferably, the 1,1-dihaloformaldehyde oxime is 1,1-dibromoformaldehyde oxime or 1,1-dichloroformaldehyde oxime.

[0008] Preferably, the organic solvent is at least one of 1,1-dichloroethane, dichloromethane, 1,2-dichloroethane, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, and isobutyl acetate. Preferably, the organic solvent is at least one of dichloromethane, 1,2-dichloroethane, n-butyl acetate, and isobutyl acetate.

[0009] As a preferred technical solution, the acid binding agent is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, triethylamine, diethylamine, ethylenediamine, diisopropylamine, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium formate, potassium formate, sodium acetate, potassium acetate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate. Preferably, the acid binding agent is one of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, and triethylamine.

[0010] As a preferred technical solution, the molar ratio of the 1,1-dihaloformaldehyde oxime, the acid binding agent and isobutylene is 1:(1-3):(1-5), preferably 1:(1.5-2.5):(3.5-5).

[0011] As a preferred technical solution, the reaction temperature is 0-100°C, preferably 0-50°C, and further preferably 5-45°C, including 5°C, 10°C, 15°C, 20°C, 25°C, 30, 35°C, 40°C, and 45°C.

[0012] As a preferred technical solution, the reaction residence time is 2-5h, preferably 2-4h.

[0013] The present invention continuously synthesizes 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole by adopting a tower packing reactor, thereby improving the automation and intelligentization level, reducing the safety risk, and making the industrial process safer, more environmentally friendly and more reliable. Specifically, the molar ratio and reaction residence time of 1,1-dihalogenformaldehyde oxime, the acid binding agent and the isobutylene are controlled by comprehensively controlling the flow rate of the organic solution of 1,1-dihalogenformaldehyde oxime, the acid binding agent and the isobutylene entering the tower packing reactor, thereby ensuring the purity and yield of the prepared 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole. In particular, when the molar ratio of 1,1-dihaloformaldehyde oxime, the acid binding agent and isobutylene is 1:(1.5-2.5):(3.5-5) and the reaction residence time is controlled to be 2-4 hours, the yield of the prepared 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole is 95.46-97.74% and the purity is 95.60-97.20%; the yield of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole is 95.70-96.38% and the purity is 96.20-98.30%.

[0014] As a preferred technical solution, the flow rate of the organic solution of 1,1-dihaloformaldehyde oxime entering the tower packed reactor is 2.08-4.17 g / min.

[0015] As a preferred technical solution, the flow rate of the acid binding agent entering the tower packed reactor is 0.84-9.15 g / min.

[0016] As a preferred technical solution, the flow rate of the isobutylene entering the tower packed reactor is 0.77-2.31 g / min.

[0017] As a preferred technical solution, the post-treatment includes continuous extraction separation and organic layer concentration and distillation.

[0018] As a preferred technical solution, the 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole is 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole or 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole.

[0019] Preferably, the yield of the 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole is 95.46-97.74% and the purity is 95.60-97.20%.

[0020] Preferably, the yield of the 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole is 95.70-96.38% and the purity is 96.20-98.30%.

[0021] Beneficial Effects

[0022] 1. The present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, which realizes the automated controlled continuous production of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, improves the production efficiency and yield, and is suitable for industrial production.

[0023] 2. The present invention adopts a tower packed reactor to continuously synthesize 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, thereby improving the level of automation and intelligence, reducing safety risks, and making the industrial process safer, more environmentally friendly, and more reliable.

[0024] 3. The present invention controls the molar ratio of 1,1-dihaloformaldehyde oxime, the acid binding agent and the isobutylene and the reaction residence time by comprehensively controlling the flow rate of the organic solution of 1,1-dihaloformaldehyde oxime, the acid binding agent and the isobutylene entering the tower packed reactor, thereby ensuring the purity and yield of the prepared 3-halo-5,5-dimethyl-4,5-dihydroisoxazole.

[0025] 4. The present invention controls the molar ratio of 1,1-dihaloformaldehyde oxime, acid binding agent and isobutylene to 1:(1.5-2.5):(3.5-5) and the reaction residence time to 2-4h, so that the yield of the prepared 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole is 95.46-97.74% and the purity is 95.60-97.20%; the yield of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole is 95.70-96.38% and the purity is 96.20-98.30%.

[0026] 5. The present invention improves the yield of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole from 85% to more than 95% on the basis of ensuring its purity, and has extremely high market promotion and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the structure of the tower packed reactor in Example 1 of the present invention, wherein 1 is the feed port for the organic solution of 1,1-dihaloformaldehyde oxime, 2 is the feed port for the acid binding agent, 3 is the feed port for isobutylene, and 4 is the discharge port.

[0028] Figure 2 This is a liquid chromatogram of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole prepared in an example of the present invention, wherein 1 is the solvent and 2 is SLRDS1-10 (3-chloro-5,5-dimethyl-4,5-dihydroisoxazole).

[0029] Figure 3 This is a GC-MASS (gas chromatography mass spectrometry) chart of 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole prepared in an example of the present invention.

[0030] Figure 4 This is a GC-MASS (gas chromatography mass spectrometry) chart of 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole prepared in an example of the present invention. DETAILED DESCRIPTION

[0031] Example 1

[0032] Embodiment 1 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 20wt% 1,1-dibromoformaldehyde oxime dichloromethane solution (500g, 0.49mol, 1eq.) is fed into a tower packing reactor (see Figure 1) at a rate of 4.17g / min and 12wt% potassium bicarbonate aqueous solution (616.96g, 0.74mol, 1.5eq.) is fed into a tower packing reactor (see Figure 1) through an external T-type mixer at a rate of 5.14g / min using a peristaltic pump. Figure 1 ), at the same time, isobutylene (96.82 g, 1.72 mol, 3.5 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 0.81 g / min, and the reaction temperature (15° C.) and the reaction residence time (120 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 4 )87.1g, content 96.2%, yield 95.5%.

[0033] Example 2

[0034] Embodiment 2 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 20wt% 1,1-dichloroformaldehyde oxime n-butyl acetate solution (500g, 0.88mol, 1eq.) is fed into a tower packing reactor (see Figure 2) at a rate of 4.17g / min and 12wt% potassium bicarbonate aqueous solution (1098.4g, 1.32mol, 1.5eq.) is fed into a tower packing reactor (see Figure 2) through an external T-type mixer at a rate of 9.15g / min and 1,1-dihalogenformaldehyde oxime organic solution feed port 1 and acid binding agent feed port 2 respectively by a peristaltic pump. Figure 1 ), at the same time, isobutylene (172.4 g, 3.07 mol, 3.5 eq.) was added to the reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 1.43 g / min, and the reaction temperature (5°C) and the reaction residence time (120 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 2 ,3 )115.2g, content 97.4%, yield 95.7%.

[0035] Example 3

[0036] Embodiment 3 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 30wt% 1,1-dibromoformaldehyde oxime in 1,2-dichloroethane solution (500g, 0.74mol, 1eq.) is fed into a tower packing reactor (see Figure 3) at a rate of 2.78g / min by a peristaltic pump and triethylamine (151.2g, 1.48mol, 2eq.) is fed into a tower packing reactor (see Figure 3) at a rate of 0.84g / min from an organic solution feed port 1 of 1,1-dihalogenformaldehyde oxime and an acid binding agent feed port 2 through an external T-type mixer. Figure 1 ), at the same time, isobutylene (207.5 g, 3.7 mol, 5 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 1.15 g / min, and the reaction temperature (45° C.) and the reaction residence time (180 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 4 )134.6g, content 95.6%, yield 97.74%.

[0037] Example 4

[0038] Example 4 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dichloroformaldehyde oxime in 1,2-dichloroethane solution (500g, 1.1mol, 1eq.) is fed into a tower packing reactor (see Figure 1) at a rate of 4.17g / min and triethylamine (224.3g, 2.19mol, 2eq.) is fed into a tower packing reactor (see Figure 1) at a rate of 1.87g / min through a T-type mixer outside the tower. Figure 1 ), at the same time, isobutylene (277 g, 4.9 mol, 4.5 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 2.31 g / min, and the reaction temperature (5°C) and the reaction residence time (120 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 2 , 3 )146.4g, content 96.2%, yield 96.1%.

[0039] Example 5

[0040] Embodiment 5 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dibromoformaldehyde oxime n-butyl acetate solution (500g, 0.62mol, 1eq.) is fed into a tower packing reactor (see Figure 5) at a rate of 2.78g / min and 25wt% sodium carbonate aqueous solution (653.2g, 1.54mol, 2.5eq.) is fed into a tower packing reactor (see Figure 5) at a rate of 3.63g / min through a T-type mixer outside the tower. Figure 1 ), at the same time, isobutylene (138.3 g, 2.46 mol, 4 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 0.77 g / min, and the reaction temperature (35° C.) and the reaction residence time (180 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 4 )109.8g, content 97.2%, yield 97.27%.

[0041] Example 6

[0042] Example 6 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dichloroformaldehyde oxime n-butyl acetate solution (500g, 1.1mol, 1eq.) is fed into a tower packing reactor (see Figure 5) at a rate of 2.1g / min and 40wt% potassium carbonate aqueous solution (947.7g, 2.74mol, 2.5eq.) is fed into a tower packing reactor (see Figure 5) at a rate of 3.95g / min through a T-type mixer outside the tower. Figure 1 ), at the same time, isobutylene (246.2 g, 4.39 mol, 4 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 1 g / min, and the reaction temperature (50° C.) and the reaction residence time (240 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 2 , 3 )143.7g, content 98.3%, yield 96.4%.

[0043] Comparative Example 1

[0044] Comparative Example 1 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dibromoformaldehyde oxime dichloromethane solution (500g, 0.62mol, 1eq.) is fed into a tower packing reactor (see Figure 1) at a rate of 8.3g / min by a peristaltic pump and 25wt% sodium carbonate aqueous solution (522.56g, 1.23mol, 2eq.) is fed into a tower packing reactor (see Figure 1) from an organic solution feed port 1 of 1,1-dihalogenformaldehyde oxime and an acid binding agent feed port 2 through an external T-type mixer at a rate of 8.71g / min. Figure 1 ), at the same time, isobutylene (207.5 g, 3.7 mol, 6 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 3.46 g / min, and the reaction temperature (5° C.) and the reaction residence time (60 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 4 )98.3g, content 94.8%, yield 84.9%.

[0045] Comparative Example 2

[0046] Comparative Example 2 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dichloroformaldehyde oxime n-butyl acetate solution (500g, 1.1mol, 1eq.) is fed into a tower packing reactor (see FIG. 1 ) at a rate of 16.7g / min and 25wt% sodium carbonate aqueous solution (1023.3g, 2.4mol, 2.2eq.) is fed into a tower packing reactor (see FIG. 1 ) through an external T-type mixer at a rate of 34.1g / min. Figure 1 ), at the same time, isobutylene (246.2 g, 4.39 mol, 4 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 8.21 g / min, and the reaction temperature (80° C.) and the reaction residence time (30 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 2 , 3 )124.9g, content 95.4%, yield 81.3%.

[0047] Comparative Example 3

[0048] Comparative Example 3 of the present invention provides a continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, comprising the following steps: 25wt% 1,1-dibromoformaldehyde oxime in 1,2-dichloroethane solution (500g, 0.62mol, 1eq.) is fed into a tower packing reactor (see FIG. 1 ) at a rate of 4.17g / min and 40wt% potassium carbonate aqueous solution (745.2g, 2.16mol, 3.5eq.) is fed into a tower packing reactor (see FIG. 1 ) through an external T-type mixer at a rate of 6.21g / min. Figure 1 ), at the same time, isobutylene (103.7 g, 1.85 mol, 3 eq.) was added to the tower packing reactor from the isobutylene feed port 3 at the bottom of the tower at a rate of 0.86 g / min, and the reaction temperature (50° C.) and the reaction residence time (120 min) in the tower packing reactor were controlled to react. After the feeding was completed, the material was discharged from the discharge port 4, and after continuous extraction and separation, the organic layer was concentrated and distilled to obtain 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole (see Figure 2 , 3 )102.3g, content 94.2%, yield 87.83%.

Claims

1. A continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole, characterized in that: The method comprises at least the following steps: adding an organic solution of 1,1-dihaloformaldehyde oxime, an acid binding agent and isobutylene into a tower packing reactor, controlling the reaction temperature and the reaction residence time in the tower packing reactor to carry out the reaction, and after the reaction is completed, post-processing is performed to obtain 3-halo-5,5-dimethyl-4,5-dihydroisoxazole.

2. The continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 1, characterized in that: The method comprises at least the following steps: an organic solution of 1,1-dihaloformaldehyde oxime and an acid-binding agent are introduced into a tower packing reactor through a T-type mixer outside the tower, and isobutylene is introduced into the tower packing reactor from the bottom of the tower packing reactor, and the reaction temperature and the reaction residence time in the tower packing reactor are controlled to react, and after the reaction is completed, 3-halo-5,5-dimethyl-4,5-dihydroisoxazole is obtained through post-treatment.

3. The continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 2, characterized in that: The organic solution of 1,1-dihalogenformaldehyde oxime comprises 1,1-dihalogenformaldehyde oxime and an organic solvent. The mass concentration of 1,1-dihalogenformaldehyde oxime in the organic solution of 1,1-dihalogenformaldehyde oxime is 15-40%.

4. The method for continuous preparation of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 3, characterized in that: The organic solvent is at least one of 1,1-dichloroethane, dichloromethane, 1,2-dichloroethane, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate and isobutyl acetate.

5. The method for continuous preparation of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 4, characterized in that: The acid binding agent is selected from at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, triethylamine, diethylamine, ethylenediamine, diisopropylamine, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide, sodium formate, potassium formate, sodium acetate, potassium acetate, sodium phosphate, potassium phosphate, disodium hydrogen phosphate, and dipotassium hydrogen phosphate.

6. The method for continuous preparation of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 5, characterized in that: The molar ratio of the 1,1-dihaloformaldehyde oxime, the acid binding agent and isobutylene is 1:(1-3):(1-5).

7. The method for continuous preparation of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 6, characterized in that: The reaction temperature is 0-100°C.

8. The continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to claim 7, characterized in that: The reaction residence time is 2-5h.

9. The continuous preparation method of 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole according to any one of claims 1 to 8, characterized in that: The 3-halogen-5,5-dimethyl-4,5-dihydroisoxazole is 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole or 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole. The yield of the 3-bromo-5,5-dimethyl-4,5-dihydroisoxazole is 95.46-97.74% and the purity is 95.60-97.20%. The yield of the 3-chloro-5,5-dimethyl-4,5-dihydroisoxazole is 95.70-96.38% and the purity is 96.20-98.30%.

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