A method for preparing 1,1′-ethylene-2,2′-bipyridine dichloro salt

Abstract

This invention provides a method for preparing 1,1'-ethylene-2,2'-bipyridine dichlorosalt, belonging to the field of chemical synthesis. The method includes: dissolving 1,2-dichloroethane and an organic amine in a first solvent, and carrying out a first reaction under first reaction conditions to obtain a geminal quaternary ammonium chloride; dissolving the geminal quaternary ammonium chloride and 2,2-bipyridine in a second solvent, and carrying out a second reaction under second reaction conditions to obtain 1,1'-ethylene-2,2'-bipyridine dichlorosalt. Using a dichlorosalt with two quaternized ends, which is relatively easy to synthesize from 1,2-dichloroethane and an organic amine, as a precursor, and utilizing the high boiling point and the ability to dissociate and release carbocations at certain temperatures, this substance is reacted with 2,2-bipyridine via ion exchange as an intermediate medium to generate low-cost diquat dichlorosalt. This method has mild reaction conditions and does not introduce catalysts that are difficult to process laterally. Under optimal reaction conditions, the yield of diquat dichlorosalt is as high as 95%.

Description

Technical Field

[0001] This application relates to the field of chemical synthesis technology, and in particular to a method for preparing 1,1′-ethylene-2,2′-bipyridine dichloro salt. Background Technology

[0002] Diquat can be used for weed control in fields, orchards, non-cultivated land, and before harvest. It can also be used to prune the stems and leaves of potatoes and sweet potatoes. Currently, commercially available diquat is diquat dibromosalt (1,1′-ethylene-2,2′-bipyridine dibromosalt), which is synthesized from 1,2-dibromoethane and 2,2-bipyridine, as shown below:

[0003]

[0004] However, the high price of 1,2-dibromoethane increases the production cost of dibromodichlorodimethyl dichloride. Dichloride's herbicidal action is cation-based, independent of anions, and production costs can be reduced by changing the type of anion in dichloride. Compared to 1,2-dibromoethane, 1,2-dichloroethane has a similar chemical structure and properties, and its price is only one-tenth that of 1,2-dibromoethane, making it a suitable raw material for dichloride synthesis. Therefore, developing dichloride dichlorodichloride with chloride anions is an effective way to reduce the synthesis cost of dichloride.

[0005] However, since the reactivity of 1,2-dichloroethane is much lower than that of 1,2-dibromoethane, the key is to achieve efficient and low-cost conversion between 1,2-dichloroethane and 2,2-bipyridine to prepare dichlorvos dichloride.

[0006] Existing technologies include methods for directly synthesizing dichlorvos dichloroate (1,1′-ethylene-2,2′-bipyridine dichloroate) from 1,2-dichloroethane and 2,2-bipyridine, such as the method disclosed in Chinese patent CN 113214258A, which uses K... +Using MgO@Al2O3 as a catalyst and nitrobenzene as a solvent, a method for the direct reaction of 1,2-dichloroethane and 2,2-bipyridine to prepare diquat dichloride is catalyzed at 130℃~160℃ and 1MPa~3MPa. Chinese patent CN 113072555A discloses a method for the direct reaction of 1,2-dichloroethane and 2,2-bipyridine to prepare diquat dichloride in a fixed-bed reactor using CuO / γ-Al2O3 as a catalyst at 140℃~300℃ and 0.1MPa~5MPa. Chinese patent CN 112500411A discloses a method for the direct reaction of 1,2-dichloroethane and 2,2-bipyridine to prepare diquat dichloride using 2-(2-pyridyl)-1,2-dihydropyridine as a catalyst at 200℃ and 1.3MPa, with a yield greater than 89.8%. The methods proposed in the aforementioned patents for directly synthesizing dichlorvos dichlorvos from 1,2-dichloroethane and 2,2-bipyridine all require high temperature and high pressure conditions, placing high demands on the equipment. In addition, the introduction of catalysts increases the difficulty of product separation.

[0007] Meanwhile, existing technologies include methods for preparing diquat dichloroate from diquat dibromide. US Patent 3803147 reports a method for preparing diquat dichloroate from diquat dibromide under the action of dilute hydrochloric acid and air; Chinese Patent CN 107573342A discloses a method for preparing diquat dichloroate from diquat dibromide, hydrochloric acid, and liquid bromine, with a product yield of 98%; Chinese Patent CN 106279166A discloses a method for preparing diquat dichloroate from diquat dibromide by oxidation with hydrogen peroxide and acidification with hydrochloric acid, with a product yield greater than 80%; Chinese Patent CN 106220629A reports a method for oxidizing diquat dibromide to bromine and diquat dichloroate by liquid chlorine, with a product yield greater than 95%. All four methods for preparing diquat dichloroate require the oxidation of bromide ions to bromine, the recovery of bromine, and its conversion into dibromoethane to be feasible. However, the process is complex, the route has low economic value, and the approval process for using liquid bromine is difficult.

[0008] Therefore, how to achieve efficient, low-cost, and relatively mild preparation of dichlorvos dichlorvos under the interaction of 1,2-dichloroethane and 2,2-bipyridine has become an urgent problem to be solved. Summary of the Invention

[0009] This application provides a method for preparing 1,1′-ethylene-2,2′-bipyridine dichlorosalt. By means of ion exchange, a gemini quaternary ammonium chloride is used as an intermediate medium to react with 2,2-bipyridine to generate diquat dichlorosalt, so as to realize the preparation of 1,1′-ethylene-2,2′-bipyridine dichlorosalt from 1,2-dichloroethane and 2,2-bipyridine under relatively mild conditions.

[0010] In a first aspect, this application provides a method for preparing 1,1′-ethylene-2,2′-bipyridine dichloro salt, the method comprising:

[0011] 1,2-Dichloroethane and an organic amine were dissolved in a first solvent, and a first reaction was carried out under the first reaction conditions to obtain a geminal quaternary ammonium chloride.

[0012] The gemini quaternary ammonium chloride and 2,2-bipyridine were dissolved in a second solvent, and a second reaction was carried out under the second reaction conditions to obtain 1,1′-ethylene-2,2′-bipyridine dichloride.

[0013] Optionally, the organic amine is a tertiary amine.

[0014] Optionally, the tertiary amine includes at least one selected from triethylamine, trihexylamine, triethylenediamine, triisopropylamine, N,N-diethylmethylamine, N,N-diisopropylmethylamine, and N-ethyldiisopropylamine.

[0015] Optionally, the generated organic amine is removed during the second reaction.

[0016] Optionally, solid-liquid separation can be performed after the second reaction is completed to recover excess 2,2-bipyridine.

[0017] Optionally, the molar ratio of 1,2-dichloroethane to the organic amine is 1:(2-6), and the molar ratio of the gemini quaternary ammonium chloride to the 2,2-bipyridine is 1:(1-2).

[0018] Optionally, the first solvent includes at least one of ethanol, methanol, acetonitrile, acetone and tetrahydrofuran, and the second solvent includes at least one of benzene, toluene, DMF and nitrobenzene.

[0019] Optionally, the first reaction conditions include: a reaction temperature of 25℃ to 80℃ and a reaction time of 3h to 6h.

[0020] Optionally, the second reaction conditions include: a reaction temperature of 90℃~150℃ and a reaction time of 8h~12h.

[0021] Secondly, this application provides a herbicide comprising 1,1′-ethylene-2,2′-bipyridine dichloride prepared by the method described in any one of the embodiments of the first aspect.

[0022] The technical solutions provided in this application have the following advantages compared with the prior art:

[0023] This application uses a dichlorosalide with quaternized ends, which is relatively easy to synthesize from 1,2-dichloroethane and organic amines, as a precursor. Taking advantage of the high boiling point of this substance and its ability to dissociate and release carbon positrons at a certain temperature, it is reacted with 2,2-bipyridine via ion exchange to generate low-cost dichlorvos dichlorosalide.

[0024] Furthermore, the method for preparing diquat dichloride provided in this application features mild reaction conditions and does not require the introduction of catalysts that are difficult to process. Under optimal reaction conditions, the yield of diquat dichloride reaches as high as 95%. This method achieves efficient, low-cost, and relatively mild preparation of diquat dichloride from 1,2-dichloroethane and 2,2-bipyridine. The process is simple, the reaction route is short, and it is suitable for industrial applications. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0026] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A schematic flowchart illustrating a method for preparing 1,1′-ethylene-2,2′-bipyridine dichloro salt provided in this application embodiment;

[0028] Figure 2 The 1,1′-ethylene-2,2′-bipyridine dichloro salt provided in Example 3 of this application 1 H spectrum (D2O);

[0029] Figure 3 The 1,1′-ethylene-2,2′-bipyridine dichloro salt provided in Example 3 of this application 13 C spectrum (D2O). Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0032] Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0033] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0034] In one aspect, this application provides a method for preparing 1,1′-ethylene-2,2′-bipyridine dichloro salt, please refer to [link to relevant documentation]. Figure 1 The method includes:

[0035] S1. Dissolve 1,2-dichloroethane and organic amine in a first solvent, and carry out a first reaction under the first reaction conditions to obtain a geminal quaternary ammonium chloride.

[0036] S2. Dissolve the gemini quaternary ammonium chloride and 2,2-bipyridine in a second solvent, and carry out a second reaction under the second reaction conditions to obtain 1,1′-ethylene-2,2′-bipyridine dichloride.

[0037] This application utilizes a relatively easy-to-synthesize dichlorosalt with both ends quaternized from organic amines and 1,2-dichloroethane as a precursor. Taking advantage of its high boiling point and ability to dissociate and release carbocations at certain temperatures, this substance is reacted with 2,2-bipyridine via ion exchange to generate low-cost dichlorvos dichlorosalt. The organic amine is removed at any time via reactive distillation, effectively promoting the reaction depth, and the collected organic amine can be recycled for the preparation of geminal quaternary ammonium chloride. The specific reaction formula for the preparation method is shown below:

[0038]

[0039] In some embodiments, the organic amine is a tertiary amine.

[0040] In some embodiments, the tertiary amine includes at least one selected from triethylamine, trihexylamine, triethylenediamine, triisopropylamine, N,N-diethylmethylamine, N,N-diisopropylmethylamine, and N-ethyldiisopropylamine.

[0041] In some embodiments, the generated organic amine is removed during the second reaction.

[0042] Removing organic amines at any time via reactive distillation can effectively promote the forward reaction, and the collected organic amines can be recycled for the preparation of quaternary ammonium dichloro salts, reducing the preparation cost of 1,1′-ethylene-2,2′-bipyridine dichloro salt.

[0043] In some embodiments, solid-liquid separation is performed after the second reaction is completed to recover excess 2,2-bipyridine.

[0044] Specifically, after the second reaction is completed, solid-liquid separation is performed. The solid product is washed with a second solvent to obtain 1,1′-ethylene-2,2′-bipyridine dichloro salt. The washing liquid and filtrate are combined and used as raw materials for the next experiment. This allows for the recycling of excess 2,2-bipyridine and reduces the preparation cost of 1,1′-ethylene-2,2′-bipyridine dichloro salt.

[0045] In some embodiments, the molar ratio of 1,2-dichloroethane to the organic amine is 1:(2-6), and the molar ratio of the gemini quaternary ammonium chloride to the 2,2-bipyridine is 1:(1-2).

[0046] The positive effects of controlling the molar ratio of 1,2-dichloroethane to the organic amine to be 1:(2-6) are as follows: If the molar ratio is too high, the organic amine will be in excess, increasing post-processing costs; if the ratio is too low, the reaction will be incomplete, failing to obtain high-purity geminal quaternary ammonium chloride. This molar ratio can be 1:2, 1:3, 1:4, 1:5, 1:6, etc.

[0047] The positive effects of controlling the molar ratio of gemini quaternary ammonium chloride to 2,2-bipyridine to be 1:(1-2) are as follows: If the molar ratio is too high, the gemini quaternary ammonium chloride reaction will be incomplete, increasing the difficulty of post-processing the product; if the ratio is too low, the bipyridine reaction will be incomplete. This molar ratio can be 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, etc.

[0048] In some embodiments, the first solvent includes at least one of ethanol, methanol, acetonitrile, acetone, and tetrahydrofuran, and the second solvent includes at least one of benzene, toluene, DMF, and nitrobenzene.

[0049] In some embodiments, the first reaction conditions include: a reaction temperature of 25°C to 80°C and a reaction time of 3h to 6h.

[0050] The positive effects of controlling the reaction temperature of the first reaction condition to 25℃~80℃ are as follows: Too high a temperature will result in significant solvent loss; too low a temperature will lead to incomplete reaction and reduced yield. Suitable reaction temperatures include 25℃, 30℃, 40℃, 50℃, 60℃, 65℃, 70℃, 75℃, and 80℃.

[0051] The positive effects of controlling the reaction time of the first reaction condition to 3 to 6 hours: Too short a reaction time will result in incomplete reaction and reduced yield. The reaction time can be 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 6 hours, etc.

[0052] In some embodiments, after the first reaction is completed, the reactants and solvent are removed by vacuum distillation to obtain the geminal quaternary ammonium chloride.

[0053] In some embodiments, the second reaction conditions include: a reaction temperature of 90°C to 150°C and a reaction time of 8h to 12h.

[0054] The positive effects of controlling the reaction temperature of the second reaction condition to 90℃~150℃ are as follows: Too high a temperature will cause the geminal quaternary ammonium chloride to decompose, resulting in no product or decomposition of the product, thus reducing the yield; too low a temperature will lead to incomplete reaction, also reducing the yield. Suitable reaction temperatures include 90℃, 95℃, 100℃, 120℃, 130℃, 135℃, 140℃, 145℃, and 150℃.

[0055] The positive effects of controlling the reaction time of the second reaction condition to 8h to 12h: If the reaction time is too short, the reaction will be incomplete, reducing the yield. The reaction time can be 8h, 8.5h, 9h, 10h, 11h, 12h, etc.

[0056] Secondly, this application provides a herbicide comprising 1,1′-ethylene-2,2′-bipyridine dichloride prepared by the method described in any one of the embodiments of the first aspect.

[0057] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0058] Example 1

[0059] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, and the volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 80 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride with a yield of 81%.

[0060] Example 2

[0061] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C for 4 h, and the volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. The gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain dichlorvos dichlorvos with a yield of 93%. The toluene washing solution was collected.

[0062] Example 3

[0063] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 120 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 95%.

[0064] Example 4

[0065] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C with stirring for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 140 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 92%.

[0066] Example 5

[0067] 1,2-Dichloroethane (10 mmol) and triethylamine (20 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C with stirring for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 68%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 93%.

[0068] Example 6

[0069] 1,2-Dichloroethane (10 mmol) and triethylamine (30 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, and the volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride in 83% yield. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride in 93% yield.

[0070] Example 7

[0071] 1,2-Dichloroethane (10 mmol) and triethylamine (50 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C with stirring for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 93%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 93%.

[0072] Example 8

[0073] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride, with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (10 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride, with a yield of 70%.

[0074] Example 9

[0075] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (12 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 81%.

[0076] Example 10

[0077] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (16 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 94%.

[0078] Example 11

[0079] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C with stirring for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (18 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 95%.

[0080] Example 12

[0081] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with icy acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (20 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 95%.

[0082] Example 13

[0083] 1,2-Dichloroethane (10 mmol) and triethylenediamine (40 mmol) were dissolved in 100 mL of ethanol, refluxed at 60 °C for 4 h, and the volatiles were removed and recovered under reduced pressure. The resulting solid was washed with icy acetone to obtain gemini quaternary ammonium chloride in 87% yield. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (12 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 8 h. The triethylenediamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride in 91% yield.

[0084] Example 14

[0085] 1,2-Dichloroethane (10 mmol) and triisopropylamine (40 mmol) were dissolved in 100 mL of ethanol, refluxed at 60 °C and stirred for 4 h. The volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol) and 2,2-bipyridine (14 mmol) were dissolved in 50 mL of toluene and reacted at 100 °C for 10 h. The triisopropylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride with a yield of 94%.

[0086] Example 15

[0087] 1,2-Dichloroethane (10 mmol), triethylamine (10 mmol), and the triethylamine recovered in the examples (approximately 30 mmol) were dissolved in 100 mL of acetonitrile. The mixture was refluxed and stirred at 60 °C for 4 h. The volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol), 2,2-bipyridine (10 mmol), and the washing solution from Example 2 (containing approximately 4 mmol of 2,2-bipyridine) were mixed and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride with a yield of 93%.

[0088] Example 16

[0089] 1,2-Dichloroethane (10 mmol), triethylamine (10 mmol), and the triethylamine recovered in the examples (approximately 30 mmol) were dissolved in 100 mL of acetonitrile. The mixture was refluxed and stirred at 60 °C for 4 h. The volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 92%. This gemini quaternary ammonium chloride (10 mmol), 2,2-bipyridine (10 mmol), and the washing solution from Example 2 (containing approximately 4 mmol of 2,2-bipyridine) were mixed and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride with a yield of 93%.

[0090] Example 17

[0091] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed and stirred at 60 °C for 4 h, removed and recovered under reduced pressure, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol), 2,2-bipyridine (10 mmol), and the washing solution from Example 2 (which contained approximately 4 mmol of 2,2-bipyridine) were mixed and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and the solid precipitate was filtered after the reaction and washed three times with toluene to obtain diquat chloride with a yield of 93%.

[0092] Example 18

[0093] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile and refluxed at 60 °C for 4 h with stirring. The volatiles were removed and recovered under reduced pressure. The resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol), 2,2-bipyridine (10 mmol), and the washing solution from Example 17 (which contained approximately 4 mmol of 2,2-bipyridine) were mixed and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered. After the reaction, the solid precipitate was filtered and washed three times with toluene to obtain dichlorvos dichlorvos with a yield of 93%. The toluene washing solution was collected.

[0094] Example 19

[0095] 1,2-Dichloroethane (10 mmol) and triethylamine (40 mmol) were dissolved in 100 mL of acetonitrile, refluxed at 60 °C with stirring for 4 h, removed under reduced pressure and recovered the volatiles, and the resulting solid was washed with ice-cold acetone to obtain gemini quaternary ammonium chloride with a yield of 91%. This gemini quaternary ammonium chloride (10 mmol), 2,2-bipyridine (10 mmol), and the washing solution from Example 18 (which contained approximately 4 mmol of 2,2-bipyridine) were mixed and reacted at 100 °C for 10 h. The triethylamine distilled off during the reaction was recovered, and after the reaction was completed, the solid precipitate was filtered and washed three times with toluene to obtain diquat chloride with a yield of 94%.

[0096] Furthermore, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0097] In this embodiment of the invention, by distilling off the organic amine during the second reaction and recovering the excess 2,2-bipyridine after the second reaction, the collected organic amine and 2,2-bipyridine can be used as raw materials for the next reaction, thereby realizing the recycling of organic amine and 2,2-bipyridine and reducing production costs.

[0098] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing 1,1'-ethylene-2,2'-bipyridine dichloro salt, characterized in that, The method includes: 1,2-Dichloroethane and an organic amine were dissolved in a first solvent, and a first reaction was carried out under the first reaction conditions to obtain a geminal quaternary ammonium chloride. The gemini quaternary ammonium chloride and 2,2-bipyridine were dissolved in a second solvent, and a second reaction was carried out under the second reaction conditions to obtain 1,1'-ethylene-2,2'-bipyridine dichloride; The organic amine is a tertiary amine, and the tertiary amine is at least one selected from triethylamine, triisopropylamine, N,N-diethylmethylamine, N,N-diisopropylmethylamine, and N-ethyldiisopropylamine. During the second reaction, the generated organic amine is removed; After the second reaction is completed, solid-liquid separation is performed to recover excess 2,2-bipyridine; The molar ratio of 1,2-dichloroethane to the organic amine is 1:(2~6), and the molar ratio of the gemini quaternary ammonium chloride to the 2,2-bipyridine is 1:(1~2). The first solvent is at least one of ethanol, methanol, acetonitrile, acetone and tetrahydrofuran, and the second solvent is at least one of benzene, toluene, DMF and nitrobenzene; The first reaction conditions include: a reaction temperature of 25℃~80℃ and a reaction time of 3h~6h; The second reaction conditions include: a reaction temperature of 90℃~150℃ and a reaction time of 8h~12h.

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