A method for synthesizing 1,1-dihaloformaldoxime

Abstract

The present invention discloses a method for synthesizing 1,1-dihaloformaldoxime. In this method, acetoxime reacts with halogen under the action of a catalyst and undergoes a catalytic oxidation reaction with hydrogen peroxide to produce 1,1-dihaloformaldoxime. The present invention has high atom utilization rate, is green and environmentally friendly, does not require an additional acid-binding agent, has almost no halogen-containing waste salts, and has no subsequent waste caused by the use of an acid-binding agent. Only one equivalent of halogen is required for the reaction through catalytic oxidation, solving the problem of difficult treatment of excessive halogen, solving the problem of waste salts, having high product purity and high yield, being easy to separate the product, and being convenient for post-treatment, thus simplifying the production process.

Description

Technical Field

[0001] The present invention relates to a method for synthesizing an oxime intermediate of pyroxasulfone, and specifically to a method for synthesizing 1,1-dihaloformaldoxime, an intermediate of pyroxasulfone, belonging to the technical field of organic synthesis. Background Art

[0002] Dihaloformaldoxime is commonly used in the preparation of fungicides, insecticides or drugs, as well as bioactive natural products, such as the synthesis of the key intermediate of the pesticide product pyroxasulfone, and is also used in the synthesis of acivicin and its unnatural analogue bromoacivicin.

[0003] A synthesis method was reported in the literature Tetrahedron Letters (2015), 56(13), 1635 - 1637. In this method, the amount of bromine used is greater than 1.95 equivalents and two equivalents of sodium bicarbonate are used as an acid-binding agent. This method can only use one positively charged bromine in bromine, and the acid-binding agent reaction will also generate waste salt of sodium bromide. This method has a low atom utilization rate and uses water and dichloromethane as solvents, increasing the difficulty of post-treatment.

[0004] A synthesis method was reported in the literature Tetrahedron (2012), 68(7), 1845 - 1852. In this method, the amount of bromine used is greater than 1.45 equivalents and two equivalents of sodium bicarbonate are used as an acid-binding agent, generating waste salt of sodium bromide, and using water and dichloromethane as solvents, increasing the difficulty of post-treatment.

[0005] A synthesis method was reported in the literature Organic Process Research & Development (2017), 21(10), 1588 - 1594. This method uses dipotassium hydrogen phosphate as an acid-binding agent, generating a large amount of phosphorus-containing wastewater and making the treatment of three wastes difficult.

[0006] In the above-mentioned literature, during the synthesis of dihaloformaldoxime, the amount of halogen used exceeds one equivalent, resulting in excessive halogen. The process is not green, the atom utilization rate is low, and a large amount of acid-binding agent is used. Using an acid-binding agent will bring corresponding waste salts. Whether it is an organic acid-binding agent or an inorganic acid-binding agent, it will increase the amount of waste salts. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the present invention provides a method for synthesizing 1,1-dihaloformaldoxime. This method does not use an acid-binding agent and organic solvents, and only one equivalent of halogen is required for the reaction, greatly reducing the difficulty of post-treatment and solving the problems of difficult treatment of excessive halogen and a large amount of waste salts.

[0008] The specific technical solution of the present invention is as follows:

[0009] A method for synthesizing 1,1-dihaloformaldoxime, which method comprises: catalytic oxidation reaction of acetic acid oxime with halogen and hydrogen peroxide under the action of a catalyst to generate 1,1-dihaloformaldoxime. The reaction formula is as follows:

[0010]

[0011] Furthermore, the halogen is chlorine gas or liquid bromine.

[0012] Furthermore, the catalyst is ruthenium trichloride, sodium tungstate, osmium tetroxide, manganese dioxide or ruthenium dioxide. Among them, osmium tetroxide is highly toxic. Considering from the perspective of green environmental protection, the catalyst is preferably ruthenium trichloride, sodium tungstate, manganese dioxide or ruthenium dioxide. Among them, through experiments, it is found that when the catalyst is ruthenium trichloride, the yield and purity of the obtained product are the best. Therefore, the optimal catalyst is ruthenium trichloride.

[0013] Furthermore, no organic solvent is used in the reaction, and water is used as the solvent, which has better environmental protection. The amount of water is selected according to actual needs, and generally it is sufficient to ensure the normal progress of the reaction. In the specific implementation manner of the present invention, the mass of water is 1.6 - 2 times the mass of acetic acid oxime.

[0014] Furthermore, the molar ratio of acetic acid oxime, halogen, and hydrogen peroxide is 1:1:1, where hydrogen peroxide is calculated as hydrogen peroxide.

[0015] Furthermore, the molar ratio of acetic acid oxime to the catalyst is 1:0.002 - 0.05, for example, 1:0.002, 1:0.004, 1:0.006, 1:0.008, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04,

[0017] 1:0.045, 1:0.05.

[0018] Furthermore, the reaction temperature is 0°C - 60°C, for example, 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C. The reaction time is generally 1 - 1.5 h.

[0019] Furthermore, the reaction steps are as follows: mix acetic acid oxime with the solvent water, then add a part of the halogen. After adding, add the catalyst, and then add the remaining halogen and hydrogen peroxide. After adding, carry out the reaction. After the reaction, the product can be obtained only by filtration. The product is easy to separate and the post-treatment is simple.

[0020] Furthermore, in the above reaction steps, the halogen added for the first time is 45 - 55% of the total mass of the halogen, and preferably 50% of the total mass of the halogen.

[0021] Further, in the above reaction steps, when the halogen is liquid bromine, the liquid bromine and hydrogen peroxide are added dropwise.

[0022] In the present invention, acetaldoxime reacts with a halogen in the presence of a catalyst with hydrogen peroxide to undergo a catalytic oxidation reaction to produce 1,1-dihaloformaldoxime. The advantages of the present invention are as follows:

[0023] 1. The catalytic oxidation of the present invention only requires one equivalent of halogen for the reaction, avoiding the waste of halogen, solving the problem of difficult treatment of excessive halogen, and hardly generating halogen-containing waste salts.

[0024] 2. The reaction of the present invention does not use organic solvents, which can greatly reduce VOC gases during the production process, and does not use acid-binding agents. Inorganic acid-binding agents include common inorganic acid-binding agents such as sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, etc., and organic acid-binding agents include common organic acid-binding agents such as triethylamine, DIPEA, DBU, etc. The absence of acid-binding agents greatly reduces the generation of waste salts brought by acid-binding agents.

[0025] 3. The present invention has a high atom utilization rate, high product purity and high yield.

[0026] 4. The reaction conditions of the present invention are mild, without the need for high temperature and high pressure, and have low requirements for equipment.

[0027] 5. The process of the present invention is green, environmentally friendly and efficient, greatly reducing the generation of wastewater.

[0028] 6. The product of the present invention is easy to separate, and the product can be obtained only by filtration. The post-treatment is simple and rough, greatly reducing the difficulty of post-treatment, simplifying the production process, and being suitable for large-scale industrial production.

[0029] Specific Example

[0030] The following further explains and illustrates the present invention with specific examples. The following description is only exemplary and does not limit its protection scope.

[0031] In the following examples, unless otherwise specified, the concentrations are all mass percentages.

[0032] Example 1

[0033] Take 8.9 g of acetaldoxime, dissolve it in 15 g of water, add 8 g of bromine dropwise at 25 °C. After the addition is completed, add 0.2 g of ruthenium trichloride, continue to add 8 g of bromine dropwise, and at the same time add 11.3 g of 30% hydrogen peroxide dropwise. After the addition is completed, keep the temperature at 25 °C for reaction for 1 hr. After filtration and drying, 19.8 g of white solid is obtained, with a purity of 99.5% and a yield of 97.1%.

[0034] Example 2

[0035] Take 8.9 g of acetoxime, dissolve it in 15 g of water, dropwise add 8 g of bromine at 5°C. After the addition is complete, add 0.1 g of ruthenium trichloride, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 5°C for reaction for 1 hour. After filtration and drying, 19.6 g of white solid is obtained, with a purity of 99.5% and a yield of 96.2%.

[0036] Example 3

[0037] Take 8.9 g of acetoxime, dissolve it in 15 g of water, dropwise add 8 g of bromine at 45°C. After the addition is complete, add 0.05 g of ruthenium trichloride, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 45°C for reaction for 1 hour. After filtration and drying, 19.2 g of white solid is obtained, with a purity of 99.7% and a yield of 94.4%.

[0038] Example 4

[0039] Take 8.9 g of acetoxime, dissolve it in 15 g of water, dropwise add 8 g of bromine at 25°C. After the addition is complete, add 0.05 g of ruthenium dichloride, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 45°C for reaction for 1 hour. After filtration and drying, 19 g of white solid is obtained, with a purity of 99.5% and a yield of 93.2%.

[0040] Example 5

[0041] Take 8.9 g of acetoxime, dissolve it in 15 g of water, dropwise add 8 g of bromine at 25°C. After the addition is complete, add 0.05 g of manganese dioxide, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 45°C for reaction for 1 hour. After filtration and drying, 18.9 g of white solid is obtained, with a purity of 99.7% and a yield of 92.9%.

[0042] Example 6

[0043] Take 8.9 g of acetoxime, dissolve it in 15 g of water, dropwise add 8 g of bromine at 25°C. After the addition is complete, add 0.0078 g of sodium tungstate, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 45°C for reaction for 1 hour. After filtration and drying, 18.8 g of white solid is obtained, with a purity of 99.5% and a yield of 92.2%.

[0044] Example 7

[0045] Take 8.9 g of acetaldoxime, dissolve it in 15 g of water, and introduce 3.55 g of chlorine gas at 25°C. After completion, add 0.078 g of sodium tungstate, continue to introduce 3.55 g of chlorine gas, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 25°C for reaction for 1 h. After filtration and drying, 10.7 g of white solid is obtained, with a purity of 99.1% and a yield of 93.1%.

[0046] Example 8

[0047] Take 8.9 g of acetaldoxime, dissolve it in 15 g of water, and introduce 3.55 g of chlorine gas at 25°C. After completion, add 0.1 g of ruthenium trichloride, continue to introduce 3.55 g of chlorine gas, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 25°C for reaction for 1 h. After filtration and drying, 11.1 g of white solid is obtained, with a purity of 99.1% and a yield of 96.6%.

[0048] Comparative Example 1

[0049] Take 8.9 g of acetaldoxime, dissolve it in 15 g of water, first dropwise add 8 g of bromine at 25°C, continue to dropwise add 8 g of bromine, and simultaneously dropwise add 11.3 g of 30% hydrogen peroxide. After the addition is complete, keep the temperature at 25°C for reaction for 1 h. The reaction is not completed, and a large amount of bromine remains. After adding sodium bisulfite for quenching and then performing post-treatment, 7.9 g of white solid is obtained after filtration and drying, with a purity of 98.9% and a yield of 38.6%.

Claims

1. A method for synthesizing 1,1-dihaloformaldoxime, characterized in that: Acetic acid oxime undergoes a catalytic oxidation reaction with halogen and hydrogen peroxide under the action of a catalyst to produce 1,1-dihaloformoxime; no acid-binding agent and organic solvent are used in the reaction, and the catalyst is ruthenium trichloride, sodium tungstate, osmium tetroxide, manganese dioxide or ruthenium dioxide; the molar ratio of acetic acid oxime, halogen, hydrogen peroxide and catalyst is 1:1:1:0.002-0.05, wherein the hydrogen peroxide is calculated as hydrogen peroxide.

2. The synthesis method according to claim 1, characterized in that: The halogen is chlorine gas or liquid bromine.

3. The synthesis method according to claim 1, wherein: The catalyst is ruthenium trichloride.

4. The synthesis method according to claim 1, characterized in that: The reaction is carried out in water.

5. The synthesis method according to claim 1, wherein: The reaction temperature is 0°C - 60°C.

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