A kind of preparation method of methanamide

Abstract

The invention discloses a preparation method of methanamide, wherein an aqueous solution of methanamide is added to a four-mouth bottle, and hydrochloric acid is added dropwise to adjust pH value after the temperature rises to 20-35°C for standby use; an aqueous solution of zinc sulfate is added to a reaction vessel, and an aqueous solution of methanamide with pH value adjusted is added dropwise after the temperature rises to 30-45°C, and the temperature is kept for 0.5-1 hours after the addition is completed; an aqueous solution of sodium hypochlorite is added dropwise to the system after the addition is completed, and the temperature is kept for 0.5-1 hours after the addition is completed, and ammonia is added dropwise to the system to adjust pH value, and then a stabilizer is added and kept for 1-2 hours, and then the original drug of methanamide is obtained after filtering, leaching, adding a stabilizer, and drying. The present invention adopts sodium hypochlorite as an oxidant, and no inorganic acid needs to be added during the oxidation process; the reaction is directly centrifuged after completion, and recrystallization is not required without cooling, and the yield of methanamide obtained is greater than 98%; the by-product salt is ammonium sulfate, which can also produce a certain economic value. The whole preparation process is simple to operate and easy to realize industrialization.

Description

Technical Field

[0001] The invention relates to a preparation method of metiram, in particular to the synthesis of dithiocarbamate pesticides, and belongs to the technical field of pesticide synthesis. Background Art

[0002] The pure product of methocarb is a white powder, while the industrial product is an off-white or light yellow powder with a fishy smell. It is difficult to dissolve in water and insoluble in most organic solvents, but soluble in pyridine. It is unstable to light, heat, and moisture, and easily decomposes into carbon disulfide. It easily decomposes into carbon disulfide and reduces its effectiveness when it comes into contact with alkaline substances or substances such as copper and mercury, and has low volatility.

[0003] Mancozeb is an excellent protective fungicide and a low-toxic pesticide. It has a wide range of fungicides and its control effect is significantly better than other similar fungicides. Seed treatment can prevent and treat seed and root diseases such as damping-off and root rot. Compared with various types of mancozeb, it has a significantly more effective control effect on melon downy mildew and can reduce the killing effect on beneficial predatory mites. Mancozeb is a multi-enzyme inhibitor that interferes with multiple enzyme action points of pathogen cells, so it is not easy to develop resistance. It is also beneficial to the synthesis of chlorophyll, increasing photosynthesis, and can improve the color of fruits and vegetables, making the color of fruits and vegetables brighter and the leaves greener.

[0004] At present, there are few reports on the preparation of metiram. Only Limin Chemical introduced the synthesis method of metiram in patent CN109796389A. During the oxidation process, sulfuric acid needs to be added dropwise to promote the reaction, which increases the complexity of the operation. After the reaction, cooling and crystallization are required, which also increases the cost. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a preparation method of metiram in view of the shortcomings of the prior art, wherein sodium hypochlorite is used as an oxidant, and no inorganic acid needs to be added during the oxidation process. After the reaction is completed, the reaction is directly centrifuged without cooling and recrystallization, and the yield of the obtained metiram is greater than 98%.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing metiram, comprising the following steps:

[0008] (1) adding an aqueous solution of mancozeb into a four-necked bottle, heating it to 20-35° C., and then dropping hydrochloric acid to adjust the pH for later use;

[0009] (2) adding a zinc sulfate aqueous solution into a reaction vessel, heating the temperature to 30-45° C., and then dripping the pH-adjusted mancozeb aqueous solution obtained in step (1), and completing the dripping within 1.5-2 hours. After the dripping is completed, the temperature is kept at 30-45° C. for 0.5-1 hour;

[0010] (3) After the insulation in step (2) is completed, a sodium hypochlorite aqueous solution is added dropwise to the system and the addition is completed within 0.5-1 hour. After the addition is completed, the system is kept warm at 30-45° C. for 0.5-1 hour;

[0011] (4) After the insulation in step (3) is completed, ammonia water is added dropwise to the system to adjust the pH, and then a stabilizer is added and the system is incubated at 30-45° C. for 1-2 hours;

[0012] (5) After the heat preservation in step (4) is completed, the wet base of metiram is obtained by filtering and eluting, and then a stabilizer is added to the wet base of metiram, mixed and dried to obtain the metiram technical.

[0013] In the above technical solution, in step (1), the mass concentration of the aqueous solution of manebillium is 20-25%.

[0014] In the above technical solution, in step (1), the hydrochloric acid is hydrochloric acid with a mass concentration of 5%.

[0015] In the above technical solution, in step (1), hydrochloric acid is added dropwise to the aqueous solution of manebillium to adjust the pH to 6-7.

[0016] In the above technical solution, in step (2), the zinc sulfate aqueous solution has a mass concentration of 40%-42%.

[0017] In the above technical solution, the molar ratio of manebill in the manebill aqueous solution to zinc sulfate in the zinc sulfate aqueous solution is 1:0.8-1.2, preferably 1:1.1.

[0018] In the above technical solution, in step (3), the mass concentration of the sodium hypochlorite aqueous solution is 9%-11%.

[0019] In the above technical solution, the molar ratio of manebill in the manebill aqueous solution to the sodium hypochlorite in the sodium hypochlorite aqueous solution is 1:0.05-0.5, preferably 1:0.2.

[0020] In the above technical solution, in step (4), the ammonia water has a mass concentration of 20%.

[0021] In the above technical solution, in step (4), ammonia water is added dropwise to the system to adjust the pH, and the pH is adjusted to 5-7.

[0022] In the above technical solution, in step (4) and step (5), the stabilizer is any one of paraformaldehyde, urotropine, sodium pyrosulfite and formaldehyde, or a mixture of two or more thereof, preferably sodium pyrosulfite.

[0023] In the above technical solution, in step (4), the amount of stabilizer added is 0.5%-2% of the mass of the zinc sulfate aqueous solution.

[0024] In the above technical solution, in step (5), the amount of stabilizer added is 0.5-5% of the wet basis mass of metiram, preferably 1%.

[0025] In the above technical solution, in step (5), the drying temperature is 80-120°C, preferably 100°C.

[0026] In the above technical solution, the preparation method adopts a one-pot method.

[0027] The advantages of the invention are: sodium hypochlorite is used as an oxidant, and no inorganic acid needs to be added during the oxidation process; centrifugation is performed directly after the reaction is completed, and recrystallization does not need to be cooled, and the yield of the obtained manebrine is greater than 98%; the by-product salt is ammonium sulfate, which can also generate certain economic value; the entire preparation process is simple to operate and easy to realize industrialization. DETAILED DESCRIPTION

[0028] The specific implementation of the technical solution of the present invention is described in detail below, but the present invention is not limited to the following description:

[0029] The present invention will be described below in conjunction with specific embodiments:

[0030] Embodiment 1:

[0031] Add 460g of manebrine solution (21%) to a four-necked flask, heat to 20-30°C, add hydrochloric acid (7.6g, 5%) dropwise, adjust the pH to 6-7, keep warm for 10min after the addition, and set aside; add zinc sulfate aqueous solution (172g, 40%), heat to 30-40°C, add the above manebrine solution dropwise, add dropwise within 2 hours, keep warm at 30-40°C for 0.5h after the addition; add sodium hypochlorite aqueous solution (58g, 40%), heat to 30-40°C, and add the above manebrine solution dropwise. , 10%), the addition was completed within 0.5 hours, and the mixture was kept warm at 30-40°C for 0.5h, ammonia water (1.1g, 20%) was added to adjust the pH to 5-6, formaldehyde (1g, 99%) was added and the mixture was kept warm at 35-40°C for 1h, filtered, and washed to obtain a wet base of metiram, and hexamethylenetetramine (1.6g, 99%) was added, and the mixture was evenly mixed and then dried at 100°C to obtain 114g of metiram technical with a content of 92.2% and a yield of 99%.

[0032] Embodiment 2:

[0033] Add 920g of manebrine solution (21%) to a four-necked flask, heat to 20-30°C, add hydrochloric acid (15.3g, 5%) dropwise, adjust the pH to 6-7, keep warm for 10min after the addition, and set aside; add zinc sulfate aqueous solution (328g, 40%), heat to 30-40°C, add the above manebrine solution dropwise, add within 2 hours, keep warm at 30-40°C for 0.5h after the addition; add sodium hypochlorite aqueous solution (116 g, 10%), the addition was completed within 0.5 hours, and the mixture was kept warm at 30-40°C for 0.5h, ammonia water (2.3g, 20%) was added to adjust the pH to 5-6, formaldehyde (2g, 99%) was added, and the mixture was kept warm at 35-40°C for 1h, filtered, and washed to obtain a wet base of metiram, and hexamethylenetetramine (3.2g, 99%) was added, and the mixture was evenly mixed and then dried at 100°C to obtain 229.7g of metiram technical with a content of 91.8% and a yield of 99%.

[0034] Embodiment 3:

[0035] Add 920g of manebrine solution (21%) to a four-necked flask, heat to 20-30°C, add hydrochloric acid (15.3g, 5%) dropwise, adjust the pH to 6-7, keep warm for 10min after the addition, and set aside; add zinc sulfate aqueous solution (344g, 40%), heat to 30-40°C, add the above manebrine solution dropwise, add within 2 hours, keep warm at 30-40°C for 0.5h after the addition; add sodium hypochlorite aqueous solution (116 g, 10%), the addition was completed within 0.5 hours, and the mixture was kept warm at 30-40°C for 0.5h, ammonia water (2.3g, 20%) was added to adjust the pH to 5-6, formaldehyde (2g, 99%) was added, and the mixture was kept warm at 35-40°C for 1h, filtered, and washed to obtain a wet base of metiram, and hexamethylenetetramine (3.2g, 99%) was added, and the mixture was evenly mixed and then dried at 100°C to obtain 227.9g of metiram technical with a content of 92.6% and a yield of 99%.

[0036] The above examples are only for illustrating the technical concept and technical features of the present invention, and cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing metiram, characterized in that: The following steps are involved: (1) adding an aqueous solution of mancozeb into a four-necked bottle, heating it to 20-35° C., and then dripping hydrochloric acid to adjust the pH for later use; (2) adding a zinc sulfate aqueous solution into a reaction vessel, heating the temperature to 30-45° C., and then dripping the pH-adjusted mancozeb aqueous solution obtained in step (1), and completing the dripping within 1.5-2 hours. After the dripping is completed, the temperature is kept at 30-45° C. for 0.5-1 hour; (3) After the insulation in step (2) is completed, a sodium hypochlorite aqueous solution is added dropwise to the system, and the addition is completed within 0.5-1 hour. After the addition is completed, the temperature is kept at 30-45° C. for 0.5-1 hour; (4) After the insulation in step (3) is completed, ammonia water is added dropwise to the system to adjust the pH, and then a stabilizer is added and the system is incubated at 30-45° C. for 1-2 hours; (5) After the heat preservation in step (4) is completed, filtering and eluting are performed to obtain a metiram wet base, and then a stabilizer is added to the metiram wet base, mixed and dried to obtain the metiram technical drug; In step (4) and step (5), the stabilizer is any one of paraformaldehyde and urotropine.

2. The preparation method according to claim 1, characterized in that: In step (1), the mass concentration of the manebrine aqueous solution is 20-25%; and the hydrochloric acid has a mass concentration of 5%.

3. The preparation method according to claim 1, characterized in that: In step (1), hydrochloric acid is added dropwise to the mancozeb aqueous solution to adjust the pH to 6-7.

4. The preparation method according to claim 1, characterized in that: In step (2), the zinc sulfate aqueous solution has a mass concentration of 40%-42%; the molar ratio of mancozeb in the mancozeb aqueous solution to zinc sulfate in the zinc sulfate aqueous solution is 1:0.8-1.

2.

5. The preparation method according to claim 1, characterized in that: In step (3), the sodium hypochlorite aqueous solution has a mass concentration of 9%-11%; the molar ratio of mancozeb in the mancozeb aqueous solution to the sodium hypochlorite in the sodium hypochlorite aqueous solution is 1:0.05-0.

5.

6. The preparation method according to claim 1, characterized in that: In step (4), the ammonia water has a mass concentration of 20%, and the pH of the system is adjusted to 5-7.

7. The preparation method according to claim 1, characterized in that: In step (4), the amount of stabilizer added is 0.5%-2% of the mass of the zinc sulfate aqueous solution; in step (5), the amount of stabilizer added is 0.5-5% of the mass of the metiram wet basis.

8. The preparation method according to claim 1, characterized in that: In step (5), the drying temperature is 80-120°C.

9. The preparation method according to claim 1, characterized in that: The preparation method adopts a one-pot process.