A method for continuously preparing flake diquat dichloride by a microfluidic reactor

Abstract

The invention discloses a method for continuously preparing flake diquat dichloride by a microfluidic reactor, which includes: using a feeding pump to input liquid 2,2'-bipyridine or a 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or a dichloroethane solution into the microfluidic reactor, quickly mixing and precipitating, separating solid from liquid, washing with toluene, and drying to obtain flake diquat dichloride; a dispersant is added to the liquid 2,2'-bipyridine or the 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or the dichloroethane solution, either both or one of them. The method of the invention has the advantages of simple operation, stable process, strong safety, and continuous and stable production. The synthesized diquat dichloride is in a flake structure, which can effectively avoid dust and is helpful for the production and packaging of various pesticide formulations. The method of the invention uses a surfactant, which effectively avoids the agglomeration phenomenon of diquat dichloride.

Description

Technical Field

[0001] The present invention belongs to the field of pesticide chemistry, and relates to a method for continuously preparing flake diquat dichloride by using a microfluidic reactor. Background Art

[0002] Diquat, chemically named 1,1'-ethylene-2,2'-bipyridyldibromide, with the international common name diquat and the English name 1,1'-ethylene-2,2'-bipyridyldibromide, is a non-contact herbicide and deoxidizer designed by Syngenta in France. It is also one of the most widely used herbicide products in the world at present, and its global sales volume and demand are second only to glyphosate and paraquat. As a conductive contact-killing herbicide, diquat can be quickly digested by plant tissues and will quickly lose its activity after contacting the soil. It is mostly used for weed control in fields, plantations, non-cultivated lands, before harvesting, etc., and can also be used for withering the stems and leaves of potatoes and sweet potatoes; in areas with serious Cyperaceae weeds, the combined use of diquat and paraquat has a better effect.

[0003] Diquat usually exists in the form of a monohydrate of the dibromide. The active ingredient of diquat is the cationic part, and the type of anion has no effect on its herbicidal activity, and the effects of these ion pairs on equimolar substrates are equal (J.Sci.FoodAgric., 1960, 309 - 315). The change of the diquat anion does not destroy its herbicidal activity (US2823987A). Bromine is a precious resource, while chlorine resources are rich and cheap. The raw material dibromoethane used in traditional diquat dibromide is relatively expensive, more than 10 times that of dichloroethane. Using cheap dichloroethane and bipyridine to react to produce diquat dichloride can greatly reduce the drug cost and does not reduce the drug effect at the same time, which has great industrial value. Therefore, developing a method for preparing diquat dichloride to replace diquat dibromide has important economic significance.

[0004] There are mainly the following several preparation methods for diquat dichloride:

[0005] 1. Ion exchange method: Patent US2823987A discloses that diquat dibromide solution is fully stirred and reacted with silver chloride, and silver bromide is filtered out to obtain diquat dichloride solution. This method uses expensive silver chloride as a chlorine exchanger, with high costs and no industrial significance. Ion exchange resins can also be used to obtain diquat dichloride through ion exchange, which also has no industrial significance (Brit. J. Industry. Med., 1966, 23, 133). US3803147A uses dipyridine dibromide to couple with sodium amalgam in a solvent, and the resulting 1,1'-ethylene-2,2'-bipyridine dibromide is oxidized in a dilute hydrochloric acid and air atmosphere to obtain 1,1'-ethylene-2,2'-bipyridine dichloride. This method has a long reaction step, a complex operation process, and uses flammable, explosive sodium and highly toxic mercury during the reaction process.

[0006] CN107573342A generates 1,1'-ethylene-2,2'-bipyridine dibromide by reacting 2,2'-bipyridine with dibromoethane, and then uses the 1,1'-ethylene-2,2'-bipyridine dibromide aqueous solution as a raw material to obtain a mother liquor of 1,1'-ethylene-2,2'-bipyridine dichloride with a cation content of 20 - 30% and bromination by-products through a series of post-treatments such as oxidation with hydrogen peroxide, bromine absorption, and liquid separation. This method has the prospect of industrial application, but it is necessary to first prepare diquat dibromide, and then obtain the mother liquor of 1,1'-ethylene-2,2'-bipyridine dichloride through oxidation, bromination, and multiple post-treatments, with a long process and complex operations.

[0007] 2. Chloroethanol cyclization method: GB1087052A heats 2,2'-bipyridine and 1-chloro-2-ethanol together to 130 - 170 °C to prepare 1,1'-ethylene-2,2'-bipyridine dichloride and by-product ethylene glycol. The raw material chloroethanol used in this method has a relatively high price, and the by-product ethylene glycol is troublesome to separate and purify.

[0008] 3. CN112500411A uses dichloroethane and 2,2'-bipyridine as raw materials to directly synthesize diquat dichloride in an autoclave under high temperature and high pressure. This method is simple and suitable for industrial production scale-up.

[0009] None of the above methods have prepared flaky diquat dichloride. If flaky diquat dichloride can be produced, dust can be effectively avoided, which is helpful for the production and packaging of various pesticide formulations. Summary of the Invention

[0010] The object of the present invention is to provide a new method for synthesizing flake diquat dichloride in view of the deficiencies of the prior art. This method uses a microfluidic reactor to continuously and controllably prepare flake diquat dichloride. Compared with the traditional batch reactor, due to the limitation of the microscale, the reactants in the microfluidic reactor can contact evenly and mix microscopically rapidly, greatly strengthening the mass and heat transfer processes, effectively limiting the particle size and improving the particle size distribution uniformity; by adding an appropriate surfactant to the raw materials, the agglomeration of the products can be effectively avoided.

[0011] The object of the present invention is achieved by the following technical solutions:

[0012] A method for continuously preparing flake diquat dichloride using a microfluidic reactor, the method comprising: using a feed pump to input liquid 2,2'-bipyridine or a 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or a dichloroethane solution into the microfluidic reactor, quickly mixing and precipitating, separating solid from liquid, washing with toluene, and drying to obtain flake diquat dichloride.

[0013] The liquid 2,2'-bipyridine is in a molten and heat-insulated state.

[0014] The solvent used in the 2,2'-bipyridine solution is one of ethanol, propanol, n-butanol, isobutanol, ether, benzene, toluene, xylene, chloroform or petroleum ether or two mutually soluble ones, preferably toluene and xylene.

[0015] Specifically, the 2,2'-bipyridine solution is obtained by mutually dissolving 2,2'-bipyridine and the solvent in a mass ratio of 1:1 to 1:3.

[0016] The solvent used in the dichloroethane solution is toluene and n-butanol.

[0017] Specifically, the dichloroethane solution is obtained by mutually dissolving dichloroethane and the solvent in a mass ratio of 1:1 to 3:1.

[0018] The molar ratio of dichloroethane to 2,2'-bipyridine fed is 1.1:1 to 3:1, preferably 1.2:1 to 2.2:1.

[0019] The inner diameter of the channels of the microfluidic reactor is 0.01 to 10 mm, preferably 0.2 to 1 mm; the channel length is 0.01 to 2 m, preferably 0.01 to 0.5 m.

[0020] The reaction temperature is controlled at 100 to 250 °C, preferably 150 to 220 °C, more preferably 160 to 200 °C. The reaction pressure is controlled at 0.5 to 10 MPa, preferably 0.8 to 3 MPa, more preferably 0.8 to 2 MPa.

[0021] Either or both of the described liquid 2,2'-bipyridine or 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or dichloroethane solution are added with a dispersant, and the concentration of the dispersant in the solution is 0.001 - 0.01 mol / L.

[0022] The dispersant is one or a mixture of several of methanol, ethanol, isopropanol, n-butanol, polyether sulfonate, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, ammonium dodecyl sulfonate, sodium lauryl polyoxyethylene ether sulfonate, ammonium lauryl ether sulfonate, sodium poly(naphthalene formaldehyde sulfonate), polyacrylamide, succinate sulfonate, dodecyl benzene sulfonamide, sodium dodecyl alcohol polyoxyethylene ether sulfate, triethanolamine lauryl sulfate, secondary alkyl sulfonate, sodium fatty alcohol hydroxyethyl sulfonate, sodium N-lauroyl glutamate, amide polyoxyethylene ether magnesium sulfate, sodium lauryl polyoxyethylene ether carboxylate, dodecyl phosphate, potassium dodecyl phosphate, triethanolamine dodecyl phosphate, alpha-olefin sulfonate, disodium dodecyl alcohol polyoxyethylene sulfosuccinate.

[0023] The solid-liquid separation is carried out by filtration.

[0024] Advantages of the present invention:

[0025] 1. The method of the present invention has the advantages of simple operation, stable process, strong safety, and continuous and stable production. The synthesized diquat dichloride is in a flaky structure, which can effectively avoid dust and is helpful for the production and packaging of various pesticide formulations;

[0026] 2. The method of the present invention strengthens the mass transfer and heat transfer in the reaction process through a specific microfluidic reactor.

[0027] 3. The method of the present invention uses a surfactant to effectively avoid the agglomeration phenomenon of diquat dichloride. Description of the Drawings

[0028] Figure 1 Scanning electron microscope photograph (SEM) of the flaky diquat dichloride prepared in Example 1. Detailed Embodiments

[0029] The present invention is further illustrated below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto:

[0030] Example 1

[0031] Using a flow pump, 2,2'-bipyridine (at a temperature of 100 °C and containing 0.001 mol / L sodium dodecyl sulfate) was injected into a microfluidic reactor with a pore diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane was injected at a flow rate of 19.8 g / min. The reaction temperature was controlled at 180 °C and the reaction pressure at 1 MPa. The resulting suspension was filtered, washed with toluene to remove excess 2,2'-bipyridine, and dried to obtain flaky diquat dichloride (see Figure 1 ), with a yield of 94% and a purity of 99.2%.

[0032] Example 2

[0033] Using a flow pump, a toluene solution of 2,2'-bipyridine (at a temperature of 100 °C, containing 0.001 mol / L sodium dodecyl sulfate, and with a mass ratio of 2,2'-bipyridine to toluene of 1:1) was injected into a microfluidic reactor with a pore diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane was injected at a flow rate of 11.9 g / min. The reaction temperature was controlled at 160 °C and the reaction pressure at 1 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride, with a yield of 93.5% and a purity of 99.3%.

[0034] Example 3

[0035] Using a flow pump, a n-butanol solution of 2,2'-bipyridine (at a temperature of 80 °C, containing 0.001 mol / L sodium dodecyl sulfate, and with a mass ratio of 2,2'-bipyridine to n-butanol of 1:3) was injected into a microfluidic reactor with a pore diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane was injected at a flow rate of 21.8 g / min. The reaction temperature was controlled at 180 °C and the reaction pressure at 0.8 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride, with a yield of 95.2% and a purity of 99.4%.

[0036] Example 4

[0037] Using a flow pump, a 2,2'-bipyridine toluene solution (temperature 100 °C, containing 0.001 mol / L of sodium poly(naphthalene formaldehyde sulfonate), and the mass ratio of 2,2'-bipyridine to toluene is 1:1) was injected into a microfluidic reactor with a pore inner diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane was injected at a flow rate of 29.7 g / min. The reaction temperature was controlled at 160 °C and the reaction pressure at 1 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride with a yield of 91% and a purity of 99.2%.

[0038] Example 5

[0039] Using a flow pump, a 2,2'-bipyridine toluene solution (temperature 80 °C, and the mass ratio of 2,2'-bipyridine to toluene is 1:1) was injected into a microfluidic reactor with a pore inner diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane (containing 0.001 mol / L of sodium dodecyl sulfate) was injected at a flow rate of 29.7 g / min (calculated based on dichloroethane). The reaction temperature was controlled at 180 °C and the reaction pressure at 2 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride with a yield of 88% and a purity of 99.3%.

[0040] Example 6

[0041] Under the condition of 100 °C, using a flow pump, a 2,2'-bipyridine toluene solution (the mass ratio of 2,2'-bipyridine to toluene is 1:1) was injected at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and dichloroethane (containing 0.001 mol / L of polyacrylamide) was injected at a flow rate of 24.8 g / min (calculated based on dichloroethane) into a microfluidic reactor with a pore inner diameter of 500 μm and a mixing channel of 10 cm. The reaction temperature was controlled at 160 °C and the reaction pressure at 1 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride with a yield of 89.2% and a purity of 99.4%.

[0042] Example 7

[0043] Using a flow pump, 2,2'-bipyridine (at a temperature of 100 °C and containing 0.001 mol / L sodium dodecyl sulfonate) was injected into a microfluidic reactor with a pore diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and a mixed solution of dichloroethane and toluene (mass ratio of dichloroethane to toluene is 3:1) was injected at a flow rate of 29.7 g / min (calculated based on dichloroethane). The reaction temperature was controlled at 200 °C and the reaction pressure at 1 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride with a yield of 91% and a purity of 99.2%.

[0044] Example 8

[0045] Using a flow pump, 2,2'-bipyridine (at a temperature of 100 °C and containing 0.001 mol / L sodium polynaphthalene formaldehyde sulfonate) was injected into a microfluidic reactor with a pore diameter of 500 μm and a mixing channel of 10 cm at a flow rate of 15.6 g / min (calculated based on 2,2'-bipyridine), and a mixed solution of dichloroethane and n-butanol (mass ratio of dichloroethane to n-butanol is 3:1) was injected at a flow rate of 29.7 g / min (calculated based on dichloroethane). The reaction temperature was controlled at 200 °C and the reaction pressure at 0.8 MPa. The resulting suspension was filtered, washed with toluene, and dried to obtain flaky diquat dichloride with a yield of 87% and a purity of 99.2%.

Claims

1. A method for continuously preparing flake diquat dichloride in a microfluidic reactor, characterized in that: Including: Using a feed pump to input liquid 2,2'-bipyridine or a 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or a dichloroethane solution into a microfluidic reactor, for rapid mixing and precipitation, followed by solid-liquid separation, washing with toluene, and drying to obtain flaky diquat dichloride; Among them, for the liquid 2,2'-bipyridine or the 2,2'-bipyridine solution dissolved in a solvent, dichloroethane or the dichloroethane solution, one or both of them are added with a dispersant, and the concentration of the dispersant in the solution is 0.001 - 0.01 mol / L; The dispersant is one or a mixture of several of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, ammonium dodecylsulfonate, sodium polynaphthalene formaldehyde sulfonate, and polyacrylamide.

2. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 1, characterized in that: The liquid 2,2'-bipyridine is in a molten and heat-insulated state; the solvent used for the 2,2'-bipyridine solution is one of ethanol, propanol, n-butanol, isobutanol, ether, benzene, toluene, xylene, chloroform, or petroleum ether, or two mutually soluble ones; the solvent used for the dichloroethane solution is toluene or n-butanol.

3. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 1 or 2, characterized in that: The solvent used for the 2,2'-bipyridine solution is toluene or xylene.

4. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 1, wherein: The molar ratio of the dichloroethane and 2,2'-bipyridine fed is 1.1:1 - 3:

1.

5. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 4, wherein: The molar ratio of the dichloroethane and 2,2'-bipyridine fed is 1.2:1 - 2.2:

1.

6. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 1, characterized in that: The inner diameter of the channels of the microfluidic reactor is 0.01 - 10 mm, and the channel length is 0.01 - 2 m.

7. The method for continuously preparing flake diquat dichloride by using the microfluidic reactor according to claim 6, characterized in that: The inner diameter of the channels of the microfluidic reactor is 0.2 - 1 mm, and the channel length is 0.01 - 0.5 m.

8. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 1, characterized in that: The reaction temperature is controlled at 100 - 250 °C; the reaction pressure is controlled at 0.5 - 10 MPa.

9. The method for continuously preparing flake diquat dichloride in a microfluidic reactor according to claim 8, characterized in that: The reaction temperature is controlled at 150 - 220 °C; the reaction pressure is controlled at 0.8 - 3 MPa.

10. The method for continuously preparing flake diquat dichloride by a microfluidic reactor according to claim 9, characterized in that: The reaction temperature is controlled at 160 - 200 °C; the reaction pressure is controlled at 0.8 - 2 MPa.

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