CN1543787A - Process for preparing dazomet dustless stable fine granule - Google Patents
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Abstract
A process for preparing dazomet dust free stabilized fine granules from methylamine and carbon sulfide as raw material through the steps of, diluting methylamine with water in reactor, agitating, dropping carbon sulfide and controlling reaction temperature, continuing stirring 1-2h, stewing to obtain oil layer, thus the intermediate compound N-methyl dithiocarbamic acid is prepared, adding into reactor in turn the intermediate compound N-methyl dithiocarbamic acid prepared in the previous step and the water solution of soluble macromolecular compound, surface active agent, stirring, dropping formaldehyde solution and controlling reaction temperature, stewing for filtering, thus dazomet fine granule with 100 mesh average grain diameter can be prepared by drying the filter cake.
Description
Technical Field
The invention relates to a preparation process of a dust-free stable fine granule, in particular to a preparation process of a dazomet dust-free stable fine granule, belonging to the field of agricultural chemicals.
Technical Field
Production of dazomet has been carried out for many years, and because methyl bromide is destructive to atmospheric ozone, the international food and agriculture organization forbids the use of methyl bromide after 2005, and meanwhile, dazomet is recommended by FAO as a substitute variety of methyl bromide to be popularized and applied globally. The content of raw materials of the dazomet is about 95 percent usually, the reaction yield is less than 90 percent, the formulation of the dazomet is usually powder and wettable powder, and the formulations are easy to decompose in the storage process, release hydrogen sulfide gas, damage packages and deteriorate the environment. The using method of the dazomet is a toxic soil spreading method, and dust drift frequently occurs when people use dazomet powder and wettable powder, so that harm is caused to people and other crops. On the other hand, the powder and the wettable powder have dust pollution and inconvenience in the processes of production, packaging and transportation.
In order to achieve the purpose of no dust of the dazomet preparation, people adopt various physical and chemical methods to prepare the dazomet fine granule. Through literature search, Heinz Appler, Pasteur, Germany, has found that the following patents: US5495017, with patent names: preparation of latent dustless Dual-free-3, 5-Dimethyl-1, 3, 5-Thiadiazine-2-thionine (a process for preparing a solid, non-dusting granule of tetrahydro-3, 5-Dimethyl-1, 3, 5-thiadiazole-2-thion), the patent reports that methylamine and carbon disulfide are used as raw materials to synthesize an intermediate N-methyl dithiocarbamic acid, then the intermediate N-methyl dithiocarbamic acid reacts with formaldehyde to obtain dazomet through ring closure reaction, in the patent, alkyl diamine, alkylamine and the like are added in the first step of reaction, the prepared granule of the dazomet has no dust drift and is stable, however, the process has many disadvantages, special equipment is required to be added for processing the raw dazomet, the energy consumption is large, and a large amount of hydrogen sulfide is generated, which also causes the loss of raw chemicals and the pollution of the environment, and the production cost is correspondingly increased.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a preparation process of a dazomet dust-free stable microgranule, which solves the problems of environment pollution caused by the stability and dust drift of a dazomet preparation, reduces the cost and produces a high-content, stable and uniform microgranule product.
The method is realized by the following technical scheme that methylamine and carbon disulfide are used as raw materials to synthesize an intermediate N-methyl dithiocarbamic acid, and then the intermediate N-methyl dithiocarbamic acid reacts with formaldehyde in a ring closing manner to obtain dazomet, and the method comprises the following steps:
(1) and (2) carrying out reaction in the first step, diluting methylamine in a reactor with water, starting stirring, dropwise adding carbon disulfide, controlling the reaction temperature, continuing stirring for 1-2h after the addition is finished, stopping the reaction, standing for layering, and separating out an oil layer (which can be used for the next reaction) to obtain the intermediate N-methyldithiocarbamic acid.
(2) And a second step of reaction, namely sequentially adding the intermediate N-methyldithiocarbamic acid obtained in the first step of reaction, the aqueous solution of the soluble high molecular compound and the surfactant into a reactor, starting stirring, dropwise adding a formaldehyde solution after the system is uniform, controlling the reaction temperature, continuously stirring for 0.5-1h after the addition is finished, stopping reaction, standing and filtering, and drying a filter cake to obtain the dazomet microgranule with the average particle size of 100 meshes.
The invention improves the total yield of the reaction from the original 90% to 96%, improves the content of the original drug product from 95% to more than 98%, and carries out an accelerated heat storage experiment on the product at 54 +/-2 ℃, and the decomposition rate of the product is less than 5% after 14 days.
Because the soluble high molecular compound and the surfactant are added in the reaction system in the second step, the reaction temperature is controlled at 30 ℃, the generated product is stable, dust-free and free-flowing microgranule with the content of more than 98 percent, and the average grain diameter of the microgranule is about 100 meshes. The reaction equation is as follows:
in the reaction system, the mol ratio of methylamine, carbon disulfide and formaldehyde is 1: 0.4-0.9: 1.0-1.5, the optimal ratio is 1: 0.5-0.8: 1.0-1.2, and the reaction temperature is controlled below 30 ℃.
In the second step reaction system, a soluble high molecular compound is added, and the soluble high molecular compound comprises: one or more of polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl (ethyl) cellulose, xanthan gum, arabic gum, gelatin, starch and alginic acid.
The soluble high molecular compound is added into the second step reaction system, and the dosage of the soluble high molecular compound accounts for 0.001-5% of the mass percent of the reaction system, and the optimal percentage is 0.01-2%.
The surfactant is added into the reaction system, and is anionic, cationic, nonionic or a mixture of the anionic, cationic and nonionic surfactants, and the amount of the surfactant accounts for 0.001-5% of the mass percent of the reaction system, and the optimal percentage is 0.01-2%.
Compared with the prior art, the soluble high molecular compound and the surfactant are added in the second step reaction system, the reaction temperature is controlled to be below 30 ℃, the total yield of the two steps is above 96%, the content of the generated product is more than 98%, the generated product is stable, dust-free and free-flowing particle agent, and the average particle size of the particle agent is about 100 meshes. The present invention can produce high content, stable and no dust pollution granule product, and the process has low cost, high yield and saving in apparatus, energy, manpower and area.
Detailed Description
Specific examples are provided below in connection with the process context of the invention.
Experimental example 1.
(1) 40g of 30% methylamine water solution (0.4mol) and 50ml of water are added into a 250ml three-necked flask with a stirrer, the stirrer is started, 24.4g (0.32mol) of 99% carbon disulfide is slowly dripped, the three-necked flask is cooled by a cold water bath while the carbon disulfide is dripped, the reaction temperature is kept not higher than 30 ℃, the reaction is carried out for 1.5h, and then the three-necked flask is kept stand and layered to separate out an oil phase (9.2 g of the oil phase can be used for the next reaction), 106g of 25.8% intermediate N-methyldithiocarbamic acid is obtained, and the yield is 99.39%.
(2) 106g of 25.9 percent intermediate N-methyldithiocarbamic acid, 1g of nonylphenol polyoxyethylene ether (N is 20) and 40ml of 5 percent polyvinyl alcohol aqueous solution (1799) are sequentially added into a 250ml three-necked flask with a stirrer, the stirrer is started, 33g of 37 percent formaldehyde aqueous solution (0.4mol) is started to be dripped, after dripping is completed within about 20 minutes, the three-necked flask is cooled by a cold water bath while dripping the formaldehyde, the reaction temperature is maintained not to be more than 30 ℃, standing and filtering are carried out after 1 hour of reaction, a filter cake is dried to obtain 32.1g of the dazomet microgranule with the average grain size of 100 meshes and the content of 98.5 percent, and the yield is 97.58 percent. The product was subjected to accelerated heat storage experiments at 54. + -. 2 ℃ and a decomposition rate of 3.48% was measured after 14 days.
Experimental example 2.
(1) 40g of 30% methylamine water solution (0.4mol) and 50ml of water are added into a 250ml three-necked flask with a stirrer, the stirrer is started, 24.4g (0.32mol) of 99% carbon disulfide (9.2 g of oil layer separated out in the experimental example 1) is slowly dripped, the three-necked flask is cooled by a cold water bath while the carbon disulfide is dripped, the reaction temperature is kept to be not more than 30 ℃, and after 100 minutes of reaction, the three-necked flask is kept stand and separated out to obtain 106g of 25.9% intermediate N-methyldithiocarbamic acid (9.2 g of oil phase can be used for the next reaction), and the yield is 99.47%.
(2) 106g of 25.9 percent intermediate N-methyl dithiocarbamic acid, 0.2g of nonylphenol polyoxyethylene ether (N is 20) and 40ml of 5 percent polyvinylpyrrolidone aqueous solution (K30) are sequentially added into a 250ml three-necked flask with a stirrer, the stirrer is started, 33g of 37 percent formaldehyde aqueous solution (0.4mol) is started to be dropwise added after about 20 minutes, the three-necked flask is cooled by a cold water bath while formaldehyde is dropwise added, the reaction temperature is maintained not to exceed 30 ℃, the mixture is left to stand and filter after 1 hour of reaction, 31.9g of the dazomet microgranule with the average particle size of 100 meshes and the content of 98.5 percent is obtained by drying, and the yield is 97.5 percent. The product was subjected to accelerated heat storage test at 54. + -. 2 ℃ and after 14 days, the decomposition rate was 3.72%.
Experimental example 3.
(1) 40g of 30% methylamine water solution (0.4mol) and 50ml of water are added into a 250ml three-necked flask with a stirrer, the stirrer is started, 15.2g (0.2mol) of carbon disulfide (9.2 g of the oil layer separated out in the experimental example 2) is slowly dripped, the three-necked flask is cooled by a cold water bath while the carbon disulfide is dripped, the reaction temperature is maintained not to exceed 30 ℃, the mixture is kept stand for demixing after 1.5h of reaction, an oil phase (which can be used for the next reaction) is separated out, 106g of 25.5% intermediate N-methyldithiocarbamic acid is obtained, and the yield is 98.24%.
(2) 106g of 25.6 percent intermediate N-methyldithiocarbamic acid, 2g of sodium dodecyl sulfate and 40ml of 1 percent polyvinyl alcohol aqueous solution (1799) are sequentially added into a 250ml three-necked flask with a stirrer, the stirrer is started, 39g of 37 percent formaldehyde aqueous solution (0.48mol) is added dropwise after about 20 minutes, the three-necked flask is cooled by a cold water bath while adding the formaldehyde, the reaction temperature is maintained to be not more than 30 ℃, the mixture is kept standing and filtered after 1 hour of reaction, and the mixture is dried to obtain 31.8g of the dazomet microgranule with the average grain size of 100 meshes and the content of 98.2 percent, and the yield is 98.1 percent. The product was subjected to accelerated heat storage at 54. + -. 2 ℃ and after 14 days it was found to have a decomposition rate of 4.18%.
Experimental example 4
(1) 40g of 30% methylamine water solution (0.4mol) and 50ml of water are added into a 250ml three-necked flask with a stirrer, the stirrer is started, 18.4g (0.24mol) of carbon disulfide is slowly dropped, the three-necked flask is cooled by a cold water bath while dropping the carbon disulfide, the reaction temperature is maintained not to exceed 30 ℃, the reaction is kept for 1.5h, the three-necked flask is kept stand for layering and an oil phase is separated (3.2g of the oil phase can be used for the next reaction), 105g of 26.2% intermediate N-methyl dithiocarbamic acid is obtained, and the yield is 99.6%.
(2) 105g of 26.2 percent intermediate N-methyldithiocarbamic acid, 3.6g of sodium dodecyl sulfate and 40ml of 10 percent gelatin aqueous solution are sequentially added into a 250ml three-necked flask with a stirrer, the stirrer is started, 36g of 37 percent formaldehyde aqueous solution (0.44mol) is added dropwise, the three-necked flask is cooled by a cold water bath while the formaldehyde is added dropwise, the reaction temperature is kept to be not more than 30 ℃, the mixture is kept still and filtered after reacting for 1h, and the mixture is dried to obtain 31.5g of the dazomet microgranule with the average particle size of 100 meshes and the content of 99.2 percent, and the yield is 96.8. The product was subjected to accelerated heat storage test at 54. + -.2 ℃ and after 14 days, the decomposition rate was 3.36%.
Experimental example 5.
(1) 40g of 30% methylamine water solution (0.4mol) and 50ml of water are added into a 250ml three-necked flask with a stirrer, the stirrer is started, 18.4g (0.24mol) of carbon disulfide is slowly dropped, the three-necked flask is cooled by a cold water bath while dropping the carbon disulfide, the reaction temperature is maintained not to exceed 30 ℃, the reaction is kept for 1.5h, the three-necked flask is kept stand for layering and an oil phase is separated (3.2g of the oil phase can be used for the next reaction), 105g of 26.1% intermediate N-methyl dithiocarbamic acid is obtained, and the yield is 99.3%.
(2) 105g of 26.2 percent intermediate N-methyl dithiocarbamic acid, 0.2g of sodium dodecyl benzene sulfonate and 40ml of 10 percent xanthan gum aqueous solution are sequentially added into a 250ml three-necked bottle with stirring, stirring is started, 36g of 37 percent formaldehyde aqueous solution (0.44mol) is added dropwise, the three-necked bottle is cooled by a cold water bath while the formaldehyde is added dropwise to maintain the reaction temperature not to exceed 30 ℃, the three-necked bottle is kept stand and filtered after reacting for 1h, and the product is dried to obtain 31.8g of the dazomet microgranule with the average particle size of 100 meshes and the content of 99.0 percent, and the yield is 97.56 percent. The product was subjected to accelerated heat storage experiments at 54. + -. 2 ℃ and a decomposition rate of 3.75% was measured after 14 days.
Experimental example 6.
(1) Adding 80g of 30% methylamine water solution (0.8mol) and 100ml of water into a 250ml three-necked bottle with stirring, starting stirring, slowly dropwise adding 36.5g (0.48mol) of carbon disulfide, cooling the three-necked bottle by using a cold water bath while dropwise adding the carbon disulfide, keeping the reaction temperature not more than 30 ℃, reacting for 1.5h, standing for layering, separating out an oil phase (the oil phase can be used for the next reaction), and obtaining 211g of 25.8% intermediate N-methyldithiocarbamic acid, wherein the yield is 99.1%.
(2) 211g of 25.8 percent intermediate N-methyl dithiocarbamic acid, 3g of lauryl sodium sulfate, 2g of peregal and 80ml of 1 percent polyvinylpyrrolidone (K30) aqueous solution are sequentially added into a 500ml three-necked bottle with stirring, stirring is started, 72g of 37 percent formaldehyde aqueous solution (0.88mol) is started to be dropwise added, the three-necked bottle is cooled by a cold water bath while formaldehyde is dropwise added, the reaction temperature is kept not more than 30 ℃ after 1h of reaction, standing and filtering are carried out after the reaction, 64g of dazomet microgranules with the average grain size of 100 meshes and the content of 98.2 percent are obtained after drying, and the yield is 97.9 percent. The product was subjected to accelerated heat storage tests at 54. + -. 2 ℃ and a decomposition rate of 3.46% was measured after 14 days.
Claims (5)
1. A process for preparing dazomet dust-free stable microgranule is characterized in that methylamine and carbon disulfide are used as raw materials to synthesize an intermediate N-methyl dithiocarbamic acid, and then the intermediate N-methyl dithiocarbamic acid reacts with formaldehyde in a ring-closing manner to obtain dazomet, and the process comprises the following steps:
(1) the first step of reaction, diluting methylamine with water in a reactor, starting stirring, beginning to drop carbon disulfide, controlling reaction temperature, continuing stirring for 1-2 hours after the addition is finished, stopping stirring, standing for layering, and separating out an oil layer to obtain an intermediate N-methyldithiocarbamic acid;
(2) and a second step of reaction, namely sequentially adding the intermediate N-methyldithiocarbamic acid obtained in the first step of reaction, the aqueous solution of the soluble high molecular compound and the surfactant into a reactor, starting stirring, dropwise adding a formaldehyde solution after the system is uniform, controlling the reaction temperature, continuously stirring for 0.5-1h after the addition is finished, stopping reaction, standing and filtering, and drying a filter cake to obtain the dazomet microgranule with the average particle size of 100 meshes.
2. A process for preparing the gossypol dust-free and stable particle as claimed in claim 1, wherein the molar ratio of methylamine, carbon disulfide and formaldehyde in the reaction system is 1: 0.4-0.9: 1.0-1.5, the optimal ratio is 1: 0.5-0.8: 1.0-1.2, and the reaction temperature is controlled below 30 ℃.
3. The process for preparing dazomet fine dust-free particles according to claim 1 or 6, wherein a soluble polymer compound is added to the reaction system in the second step, the soluble polymer compound comprising: one or more of polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, xanthan gum, arabic gum, gelatin, starch and alginic acid.
4. A process for preparing the gossypol dust-free stable fine granules according to claim 1 or 3, wherein the soluble high molecular compound is used in an amount of 0.001-5 wt%, preferably 0.01-2 wt% based on the reaction system.
A process for preparing the gossypol dust-free stable microgranule as claimed in claim 1 or 3, wherein a surfactant is added into the reaction system in the second step, wherein the surfactant is anionic, cationic, nonionic or a mixture of the anionic, cationic and nonionic surfactants, and the amount of the surfactant is 0.001-5% by mass, preferably 0.01-2% by mass of the reaction system.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102391165A (en) * | 2011-10-18 | 2012-03-28 | 利民化工股份有限公司 | Process for producing potassium N-methyldithiocarbamate |
| CN106831649A (en) * | 2016-12-27 | 2017-06-13 | 浙江海正化工股份有限公司 | A kind of dazomet preparation technology |
| CN107353259A (en) * | 2017-09-05 | 2017-11-17 | 南通派斯第农药化工股份有限公司 | A kind of production technology of dazomet |
| CN114269157A (en) * | 2021-11-02 | 2022-04-01 | 中国农业科学院植物保护研究所 | Pesticide fine granule for aerial foliage spraying, preparation method and application thereof |
-
2003
- 2003-11-20 CN CN 200310108743 patent/CN1248580C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102391165A (en) * | 2011-10-18 | 2012-03-28 | 利民化工股份有限公司 | Process for producing potassium N-methyldithiocarbamate |
| CN102391165B (en) * | 2011-10-18 | 2014-06-04 | 利民化工股份有限公司 | Process for producing potassium N-methyldithiocarbamate |
| CN106831649A (en) * | 2016-12-27 | 2017-06-13 | 浙江海正化工股份有限公司 | A kind of dazomet preparation technology |
| CN106831649B (en) * | 2016-12-27 | 2019-09-27 | 浙江海正化工股份有限公司 | A kind of dazomet preparation process |
| CN107353259A (en) * | 2017-09-05 | 2017-11-17 | 南通派斯第农药化工股份有限公司 | A kind of production technology of dazomet |
| CN114269157A (en) * | 2021-11-02 | 2022-04-01 | 中国农业科学院植物保护研究所 | Pesticide fine granule for aerial foliage spraying, preparation method and application thereof |
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| CN1248580C (en) | 2006-04-05 |
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