Synthesis method of 2-chloropyrazine and wet electronic chemical

Abstract

The invention discloses a synthesis method of 2-chloropyrazine and a wet electron chemical, and relates to the technical field of material preparation, the synthesis method of 2-chloropyrazine comprises the following steps: carrying out cyclization reaction on chloroethylene oxide and ethylenediamine under the condition of a second catalyst and a second solvent to generate 2-chloropyrazine. In the synthesis method of 2-chloropyrazine provided by the invention, chloroethylene oxide is adopted as a chlorination reagent, and compared with a traditional chlorination reagent, the selectivity is better, generation of by-products is reduced, the toxicity and corrosion are low, the operation risk is reduced, and the requirements of green chemical industry are met. And the synthesis method has the advantages of safe raw materials, simple and efficient process, and easy industrial application.

Description

Technical Field

[0001] The invention relates to the technical field of material preparation, and in particular to a synthesis method of 2-chloropyrazine and wet electronic chemicals. Background Art

[0002] 2-Chloropyrazine is a yellow solid at room temperature. It has certain volatility, is easily soluble in organic solvents, has strong reactivity, and is easy to undergo nucleophilic substitution, addition and other reactions. It can be used in the fields of pesticides, medicines, dyes and analytical reagents.

[0003] The current preparation methods of 2-chloropyrazine face challenges, including the use of highly toxic raw materials, multiple reaction steps, complex operations, and low yields. These problems increase the safety, environmental, and economic risks of large-scale production. Summary of the invention

[0004] The purpose of the present invention is to provide a synthesis method of 2-chloropyrazine and wet electronic chemicals, and to improve the yield and purity of 2-chloropyrazine.

[0005] The present invention is achieved in that:

[0006] In a first aspect, the present invention provides a method for synthesizing 2-chloropyrazine, comprising: subjecting chloroethylene oxide to a cyclization reaction with ethylenediamine under the conditions of a second catalyst and a second solvent to generate 2-chloropyrazine.

[0007] Compared with traditional chlorination reagents, ethylene chloride has better selectivity, reduces by-product generation, is low in toxicity and corrosion, reduces operating risks, and meets the requirements of green chemical industry. In addition, the raw materials used in this synthesis method are safe, the process is simple and efficient, and it is easy to apply industrially.

[0008] In an optional embodiment, the second solvent is selected from at least one of ether and alkane; preferably one of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, and xylene;

[0009] And / or, the second catalyst is selected from at least one of Co-N4 / NC-1000, Co-N4 / NC-1100, Pt / C and Pd / C; preferably, the catalyst is selected from at least one of Co-N4 / NC-1000 and Co-N4 / NC-1100.

[0010] Optimizing the catalyst is beneficial to further improve the conversion rate of chloroethylene oxide and reduce side reactions.

[0011] In an optional embodiment, the molar ratio of chloroethylene oxide, ethylenediamine and the second catalyst is 1-2:1:0.01-0.2, preferably 1-1.2:1:0.02-0.1.

[0012] Optimizing the amount of reactants is beneficial to further improve the conversion rate of chloroethylene oxide and reduce side reactions.

[0013] In an optional embodiment, in the pre-cyclization reaction solution, the ratio of the amount of chloroethylene oxide to the volume of the second solvent is 1.1 mol / L to 1.5 mol / L.

[0014] Optimizing the concentration of reactants is beneficial to further improve the conversion rate of chloroethylene oxide and reduce side reactions.

[0015] In an optional embodiment, the temperature of the cyclization reaction is 50°C to 200°C, preferably the temperature of the cyclization reaction is 150°C to 200°C.

[0016] Optimizing the reaction temperature and time is beneficial to taking into account the reaction efficiency while further improving the conversion rate of chloroethylene oxide and reducing side reactions.

[0017] In an optional embodiment, the method further includes performing a second separation and purification on the liquid after the cyclization reaction, wherein the second separation and purification comprises: mixing the liquid after the cyclization reaction with water and then separating the phases, taking the organic phase and performing evaporation and reduced pressure distillation in sequence, collecting a 153°C-154°C fraction, and obtaining the purified 2-chloropyrazine.

[0018] Taking advantage of the property that 2-chloropyrazine is easily soluble in organic solvents, it is transferred to an organic phase, and then evaporated to preliminarily remove the organic solvent. Finally, reduced pressure distillation is performed to further purify 2-chloropyrazine to obtain 2-chloropyrazine with higher purity.

[0019] In an optional embodiment, vinyl chloride and an oxidant are subjected to an oxidation reaction under the conditions of a first catalyst and a first solvent to generate chloroethylene oxide.

[0020] The selective oxidation reaction of vinyl chloride can suppress side reactions under catalyst conditions, which is beneficial to increasing the yield of chloroethylene oxide.

[0021] In an optional embodiment, the first solvent is selected from at least one of alcohols and chlorinated hydrocarbons; preferably selected from at least one of methanol, ethanol, dichloromethane and dichloroethane;

[0022] And / or, the oxidant is a peroxide; preferably at least one selected from hydrogen peroxide, tert-butyl peroxide and peracetic acid;

[0023] And / or, the first catalyst is at least one of sodium tungstate, ammonium molybdate and salen cobalt complex; preferably at least one of sodium tungstate and ammonium molybdate.

[0024] Optimizing the catalyst, oxidant and solvent is beneficial to further inhibiting side reactions, ensuring the conversion rate of chloroethylene oxide and improving the yield of synthetic chloroethylene oxide.

[0025] In an optional embodiment, the molar ratio of the vinyl chloride, the first catalyst and the oxidant is 1:0.001-0.1:1-3, preferably 1:0.003-0.1:2-3.

[0026] Optimizing the dosage of reactants is beneficial to improving the yield of synthesizing chloroethylene oxide.

[0027] In an optional embodiment, in the liquid before the oxidation reaction, the volume ratio of the amount of vinyl chloride to the first solvent is 1.1 mol / L to 1.5 mol / L;

[0028] And / or, the temperature of the oxidation reaction is 0°C to 100°C, and the reaction time is 0.5h to 3h; preferably, the temperature of the oxidation reaction is 0°C to 50°C;

[0029] Optimizing the concentration of reactants and reaction conditions is beneficial to improving the yield of synthesizing chloroethylene oxide.

[0030] In an optional embodiment, the synthesis method further comprises performing a first separation on the liquid after the oxidation reaction, wherein the first separation comprises: mixing the liquid after the oxidation reaction with water and then separating the phases, taking the organic phase for evaporation and obtaining the crude chloroethylene oxide product.

[0031] Taking advantage of the property that chloroethylene oxide is easily soluble in organic solvents, it is transferred to an organic phase, and then evaporated to remove the organic solvent to obtain the crude chloroethylene oxide product. Since the content of components such as solvents mixed in chloroethylene oxide is relatively small, the impact on the subsequent cyclization reaction is relatively small, so purification is not required here.

[0032] In a second aspect, the present invention provides a wet electronic chemical, including 2-chloropyrazine synthesized by the method described in any one of the aforementioned embodiments, and the wet electronic chemical includes an etching solution, a stripping solution, a polishing solution or a cleaning solution.

[0033] Wet electronic chemicals are crucial in the electronics industry and are widely used in the manufacture of display screens, solar cells, LEDs, printed circuit boards, and semiconductor integrated circuits. However, most wet electronic chemicals are corrosive, especially after dry etching, which can easily damage wafers and metal substrates, leading to surface defects and dimensional deviations. Adding corrosion inhibitors containing heteroatoms such as N, O, S, and halogens to wet electronic chemicals is beneficial to protecting metal substrates. Furthermore, 2-chloropyrazine contains both chlorine atoms and pyrazine heterocycles, which can form a protective layer on the metal surface through physical and chemical adsorption, have a synergistic effect, can better protect the metal substrate, and more effectively reduce electrochemical corrosion. At the same time, compared with pyrazine compounds as sustained-release agents, the amount of sustained-release agents used can be reduced.

[0034] The present invention has the following beneficial effects:

[0035] In the synthesis method of 2-chloropyrazine provided by the present invention, chloroethylene oxide is used as a chlorination reagent, which has better selectivity than traditional chlorination reagents, reduces the generation of by-products, is low in toxicity and corrosion, reduces operation risks, and meets the requirements of green chemical industry. In addition, the raw materials used in the synthesis method are safe, the process is simple and efficient, and it is easy to be industrially applied. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0037] Research shows that multifunctional corrosion inhibitors such as pyrazine compounds have become an important direction for improving the anti-corrosion performance of wet electronic chemicals due to their superior adsorption effect. 2-Chloropyrazine, which contains chlorine atoms and pyrazine rings in its structure, can form a protective layer on the metal surface through physical and chemical adsorption, effectively reducing electrochemical corrosion.

[0038] The inventors have found through research that the preparation of 2-chloropyrazine uses highly toxic raw materials and has many reaction steps, complicated operations and low yield.

[0039] Yuan Baoqing et al. (CN103288763A) disclosed a preparation method using methyl chloroacetate as a starting material, wherein sodium 2-hydroxypyrazine is obtained by amination and cyclization. Subsequently, sodium 2-hydroxypyrazine is reacted with phosphorus oxychloride (POCl3) under the catalysis of N,N-dimethylaminopyridine (DMAP), and 2-chloropyrazine is finally obtained with a total yield of 57%, and its purity is ≥98%.

[0040]

[0041] The method is cumbersome and has a low overall yield. Excessive ammonia increases the difficulty of waste liquid treatment and environmental risks, while the high corrosiveness and toxicity of phosphorus oxychloride increase the complexity and cost of operation, bringing challenges to safety, environmental protection and economy.

[0042] Lu Huaping et al. (CN111004187A) disclosed a method of using glycine as a starting material to obtain sodium 2-hydroxypyrazine through amination and cyclization reactions, and then reacting with dichlorothionyl under the catalysis of N,N-diisopropylethylamine (DIFEA) to finally obtain 2-chloropyrazine with a total yield of 68%.

[0043]

[0044] The yield of the reaction was increased to 68%, but when using NaH, it must be operated under the protection of inert gas because it will generate hydrogen when in contact with moisture and is flammable and explosive, which increases the complexity of the operation. At the same time, the high toxicity, corrosiveness and environmental risks of thionyl chloride, coupled with the cumbersome operation process, further increase the challenges of safety, environmental protection and cost management.

[0045] The embodiment of the present invention provides a method for synthesizing 2-chloropyrazine, comprising: subjecting chloroethylene oxide and ethylenediamine to a cyclization reaction under the conditions of a second catalyst and a second solvent to generate 2-chloropyrazine.

[0046] The embodiment of the present invention provides a method for synthesizing 2-chloropyrazine, in which chloroethylene oxide is used as a chlorination reagent, which has better selectivity than traditional chlorination reagents, reduces by-product generation, is low in toxicity and corrosion, reduces operation risks, and meets the requirements of green chemical industry. In addition, the raw materials used in the synthesis method are safe, the process is simple and efficient, and it is easy to be industrially applied.

[0047] In an optional embodiment, the second solvent is selected from at least one of ether and alkane; preferably one of tetrahydrofuran, 2-methyltetrahydrofuran, toluene, and xylene;

[0048] And / or, the second catalyst is selected from at least one of Co-N4 / NC-1000, Co-N4 / NC-1100, Pt / C and Pd / C; preferably, the catalyst is selected from at least one of Co-N4 / NC-1000 and Co-N4 / NC-1100.

[0049] Co-N / NC-1000 has high catalytic activity. The single-atom cobalt site (Co-N) can effectively promote the ring-opening and cyclization reactions of chloroethylene oxide and ethylenediamine, and improve the selectivity of the target product 2-chloropyrazine. At the same time, the catalyst exhibits excellent conductivity and thermal stability after heat treatment at 1000°C, and can adapt to reaction conditions and maintain long-term activity. In addition, it uses non-precious metal cobalt as the active center, which has the advantages of low cost, environmental protection and suitability for industrial production.

[0050] Optimizing the catalyst is beneficial to further improve the conversion rate of chloroethylene oxide and reduce side reactions.

[0051] In an optional embodiment, the molar ratio of ethylene chloride, ethylenediamine and the second catalyst is 1-2:1:0.01-0.2, specifically 1:1:0.2, 1.1:1:0.18, 1.2:1:0.16, 1.3:1:0.14, 1.4:1:0.12, 1.5:1:0.10, 1.6:1:0.08, 1.7:1:0.06, 1.8:1:0.04, 1.9:1:0.03, 2.0:1:0.02 or any value between 1-2:1:0.01-0.2, preferably 1-1.2:1:0.02-0.1.

[0052] Among them, ethylene chloride and ethylenediamine are reactants. If any one of the reactants is used in excessive amounts, the conversion rate of the excess reactant will be reduced, thereby causing a waste of raw materials. The amount of catalyst used will affect the selectivity of the reaction. If the amount of catalyst used is too small, side reactions will increase, thereby causing a decrease in yield. However, if the catalyst is excessive, it will also cause a waste of the catalyst.

[0053] In an optional embodiment, in the liquid before the cyclization reaction, the ratio of the amount of chloroethylene oxide to the volume of the second solvent is 1.1 mol / L to 1.5 mol / L, specifically 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L or any value between 1.1 mol / L and 1.5 mol / L.

[0054] The amount of solvent used will affect the rate of the chemical reaction, including the rate of generating 2-chloropyrazine and the rate of side reactions. A suitable concentration of reactants is beneficial to increasing the rate of generating 2-chloropyrazine relative to the rate of by-products, thereby helping to increase the yield and purity of 2-chloropyrazine.

[0055] In an optional embodiment, the temperature of the cyclization reaction is 50°C to 200°C, specifically 50°C, 80°C, 110°C, 140°C, 170°C, 200°C or any value between 50°C and 200°C; the reaction time is 1h to 5h, specifically 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or any value between 1h and 5h; preferably, the temperature of the cyclization reaction is 150°C to 200°C.

[0056] Optimizing the reaction temperature and time is beneficial to taking into account the reaction efficiency while further improving the conversion rate of chloroethylene oxide and reducing side reactions. If the temperature is too high or too low, it will lead to a decrease in the yield of 2-chloropyrazine.

[0057] In an optional embodiment, the method further includes performing a second separation and purification on the liquid after the cyclization reaction, wherein the second separation and purification comprises: mixing the liquid after the cyclization reaction with water and then separating the phases, taking the organic phase and performing evaporation and reduced pressure distillation in sequence, collecting a 153°C-154°C fraction, and obtaining the purified 2-chloropyrazine.

[0058] The liquid after the cyclization reaction is mixed with water to quench the reaction, and the liquid after the cyclization reaction is mixed with water and then separated into phases, so that some water-soluble components in the liquid after the cyclization reaction leave the organic phase with water, and the 2-chloropyrazine is easily soluble in organic solvents. The organic solvent is transferred to the organic phase, and then evaporated, and the organic solvent is preliminarily removed under conditions higher than the boiling point of the solvent, and finally vacuum distillation is performed to further purify the 2-chloropyrazine to obtain 2-chloropyrazine with higher purity. Wherein vacuum distillation is used to improve the purification efficiency, and in an optional embodiment, atmospheric distillation can also be used.

[0059] In an optional embodiment, vinyl chloride and an oxidant are subjected to an oxidation reaction under the conditions of a first catalyst and a first solvent to generate chloroethylene oxide.

[0060] The oxidant is used to oxidize vinyl chloride, and at the same time, the selectivity of the oxidation reaction is improved under catalyst conditions, and the side reactions are inhibited, which is beneficial to improving the purity of chloroethylene oxide.

[0061] In an optional embodiment, the first solvent is selected from at least one of alcohols and chlorinated hydrocarbons; preferably selected from at least one of methanol, ethanol, dichloromethane and dichloroethane;

[0062] And / or, the oxidant is a peroxide; preferably at least one selected from hydrogen peroxide, tert-butyl peroxide and peracetic acid; hydrogen peroxide, tert-butyl peroxide and peracetic acid are used as oxidants, which have excellent active species generation mechanism and high reaction selectivity during the oxidation process, and are beneficial to improving the purity and yield of 2-chloropyrazine.

[0063] In an optional embodiment, the first catalyst is at least one of sodium tungstate, ammonium molybdate and salen cobalt complexes; preferably at least one of sodium tungstate and ammonium molybdate.

[0064] Sodium tungstate and ammonium molybdate have good oxidation activation ability and can dissociate high-valent tungsten (such as [WO]2-) or high-valent molybdenum (such as [MoO]2-), and react with peroxides to form peroxytungsten or peroxymolybdenum active intermediates. These intermediates can accurately convert vinyl chloride into chloroethylene oxide and have excellent selectivity and control over the oxidation reaction path. They can complete efficient epoxidation under mild conditions while avoiding secondary oxidation or side reactions.

[0065] Therefore, the present invention optimizes the selection of catalyst, oxidant and solvent, which is beneficial to further inhibit side reactions and ensure the conversion rate of chloroethylene oxide.

[0066] In an optional embodiment, the molar ratio of the vinyl chloride, the first catalyst and the oxidant is 1:0.001-0.1:1-3, specifically 1:0.001:3, 1:0.005:2.5, 1:0.01:2, 1:0.05:1.5, 1:0.1:1 or any value between 1:0.001-0.1:1-3, preferably 1:0.003-0.1:2-3.

[0067] Among them, vinyl chloride and oxidant are reactants. If any one of the reactants is used in excessive amounts, the conversion rate of the excess reactants will be reduced, resulting in a waste of raw materials. The amount of catalyst used will affect the selectivity of the reaction. If the catalyst is used in too little amount, side reactions will increase, resulting in a reduced yield. However, if the catalyst is used in excessive amounts, it will also result in a waste of the catalyst. Optimizing the amount of reactants is beneficial to improving the yield of synthesizing chloroethylene oxide, and thus to improving the yield of 2-chloropyrazine.

[0068] In an optional embodiment, in the liquid before the oxidation reaction, the volume ratio of the amount of vinyl chloride to the first solvent is 1.1 mol / L to 1.5 mol / L, specifically 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L or any value between 1.1 mol / L and 1.5 mol / L;

[0069] The amount of solvent used will affect the rate of the chemical reaction, including the rate of generating chloroethylene oxide and the rate of side reactions. A suitable concentration of reactants is beneficial to increasing the rate of generating chloroethylene oxide relative to the by-products, thereby helping to increase the yield and purity of 2-chloropyrazine.

[0070] In an optional embodiment, the temperature of the oxidation reaction is 0°C to 100°C, specifically 0°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C or any value between 0°C and 100°C; the reaction time is 0.5h to 2h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or any value between 0.5h and 3h; preferably, the temperature of the oxidation reaction is 0°C to 50°C;

[0071] Optimizing the reaction temperature is beneficial to balance the reaction efficiency, further improve the conversion rate of chloroethylene oxide and reduce side reactions. If the temperature is too high or too low, it will lead to a decrease in chloroethylene oxide.

[0072] In an optional embodiment, the method further includes performing a first separation on the liquid after the oxidation reaction, wherein the first separation includes: mixing the liquid after the oxidation reaction with water and then separating the phases, taking the organic phase for evaporation, and removing the solvent under conditions higher than the boiling point of the solvent to obtain the crude chloroethylene oxide product.

[0073] After the oxidation reaction, the liquid is mixed with water to stop the reaction, and at the same time, some water-soluble components are taken out of the organic phase. Taking advantage of the property that chloroethylene oxide is easily soluble in organic solvents, it is transferred to the organic phase, and then evaporated to remove the organic solvent to obtain the crude chloroethylene oxide product. Since the content of components such as solvents mixed in chloroethylene oxide is relatively small, the impact on the subsequent cyclization reaction is relatively small, so purification is not required here.

[0074] In a second aspect, the present invention provides a wet electronic chemical, including 2-chloropyrazine synthesized by the method described in any one of the aforementioned embodiments, and the wet electronic chemical includes an etching solution, a stripping solution, a polishing solution or a cleaning solution.

[0075] Wet electronic chemicals are crucial in the electronics industry and are widely used in the manufacture of display screens, solar cells, LEDs, printed circuit boards, and semiconductor integrated circuits. However, most wet electronic chemicals are corrosive, especially after dry etching, which can easily damage wafers and metal substrates, resulting in surface defects and dimensional deviations. In order to effectively protect the metal substrate, adding corrosion inhibitors containing heteroatoms such as N, O, S, and halogens to wet electronic chemicals is beneficial to protecting the metal substrate. Furthermore, 2-chloropyrazine contains both chlorine atoms and pyrazine heterocycles, which can form a protective layer on the metal surface through physical and chemical adsorption, have a synergistic effect, can better protect the metal substrate, and more effectively reduce electrochemical corrosion. At the same time, compared with pyrazine compounds as sustained-release agents, the amount of sustained-release agents used can be reduced.

[0076] The features and performances of the present invention are further described in detail below in conjunction with specific examples, wherein the sources of the second catalyst used in each example are as follows:

[0077] Preparation method of Co-N / NC composite material: The preparation method of Co-N / NC-1000 and Co-N / NC-1100 refers to the literature J.Am.Chem.Soc.2020,142,39,16861-16867 and J.Am.Chem.Soc.2017,139,17269-17272, and is prepared by heat treating a composite containing a cobalt precursor and a carbon source at 1000°C and 1100°C, wherein Co-N / NC-1000 is treated at 1000°C and Co-N / NC-1100 is treated at 1100°C. Higher temperatures contribute to higher dispersion of cobalt atoms and more stable single atomic sites, thereby optimizing catalytic performance.

[0078] Preparation method of metal salt / activated carbon composite material:

[0079] Zn(NO3)2·6H2O / activated carbon, the product can be purchased through the Aladdin reagent platform, model number Z118841.

[0080] Mn(NO3)2·4H2O / activated carbon, the product can be purchased through the Aladdin reagent platform, model number is M191978.

[0081] Cr(NO3)3·9H2O / activated carbon, the product can be purchased through the Aladdin reagent platform, model number is C116447.

[0082] Zn(NO3)2·6H2O / Mn(NO 3)2 ·4H2O / Cr(NO3)3·9H2O / activated carbon.

[0083] Dissolve one or more of Zn(NO3)2·6H2O, Mn(NO3)2·4H2O, and Cr(NO3)3·9H2O in deionized water, stir until completely dissolved, add an appropriate amount of activated carbon, and stir thoroughly to adsorb metal ions. Then, remove the solution by filtration, and dry the solid part at 60℃-100℃. If necessary, heat treatment can be performed at 300℃-500℃, and finally the final product is characterized and analyzed using methods such as XRD and SEM.

[0084] Example 1

[0085] The present application provides a method for preparing 2-chloropyrazine, and its synthetic route is:

[0086]

[0087] Among them, vinyl chloride is a compound represented by formula (IV); chloroethylene oxide is a compound represented by formula (III); ethylenediamine is a compound represented by formula (II); and 2-chloropyrazine is a compound represented by formula (I).

[0088] The specific steps include:

[0089] (1) Step 1: Synthesis of chloroethylene oxide (III):

[0090] 3.6mmol of ammonium molybdate was dissolved in 1.0L of dichloromethane, and then 1.2mol of vinyl chloride (IV) was added, followed by 3.6mol of hydrogen peroxide. The reaction mixture was heated at 30°C for 1 hour, and the reaction progress was monitored by gas chromatography at regular intervals, and the oxidation product was identified by comparison with a standard sample. After the reaction was completed, water was added to quench, the mixture was separated, the organic phase was taken, and evaporated to obtain a colorless liquid chloroethylene oxide (III) crude product, which could be directly used in the next step without purification (the yield was calculated as 100% for the next step).

[0091] (2) Step 2: Synthesis of 2-chloropyrazine (I):

[0092] 1.2 mol (i.e., the entire crude product of chloroethylene oxide (III) obtained in step 1) of chloroethylene oxide (III) obtained in step 1, 1.0 mol of ethylenediamine (II) and 20.0 mmol of Co-N4 / NC-1000 were added to 1.0 L of toluene, stirred evenly and then heated to 150° C., stirred and kept warm for 2 hours, and the reaction was monitored by TLC. After the reaction was completed, water was added to quench the reaction, the layers were separated, and the organic phase was taken and evaporated to obtain a slightly yellow transparent liquid 2-chloropyrazine (I) crude product. The crude product was purified by reduced pressure distillation with an oil pump, and the 153-154° C. fraction was collected to obtain 106.51 g of a colorless liquid compound 2-chloropyrazine (I) with a yield of 93% and a purity of up to 99.9%.

[0093] Example 2-14

[0094] The preparation method of Example 2-11 is the same as that of Example 1, except that the reaction parameters or reagents used are different. The reaction parameters, reagents, and corresponding yield and purity of 2-chloropyrazine of Example 2-11 are shown in Table 1.

[0095] Table 1:

[0096]

[0097]

[0098] Comparative Examples 1-5

[0099] The preparation methods of Comparative Examples 1-5 are the same as those of Example 1, except that the reaction parameters and reagents used are different. The reaction parameters, reagents used and corresponding yields of 2-chloropyrazine of Comparative Examples 1-5 are shown in Table 2.

[0100] Table 2:

[0101]

[0102]

[0103] Comparative Example 1, in step 1, 1.2 mol of vinyl chloride (IV) was dissolved in 1.0 L of dichloromethane, and then 3.6 mol of hydrogen peroxide was added. The reaction mixture was heated at 30° C. for 1 hour, and no conversion of vinyl chloride was detected after the reaction was completed.

[0104] Comparative Example 2, in step 2, 1.2 mol of chloroethylene oxide (III) obtained in step 1 and 1.0 mol of ethylenediamine (II) were added to 1.0 L of toluene, stirred evenly and then heated to 150° C., stirred and kept warm for 2 hours, and no conversion of ethylenediamine was detected after the reaction was completed.

[0105] The catalyst used in step 1 of comparative examples 3-5 had limited catalytic capacity, resulting in a significant decrease in the yield of 2-chloropyrazine; the catalyst used in step 2 of comparative examples 6-8 had almost no catalytic capacity, resulting in no detection of ethylenediamine conversion after the reaction; the catalyst used in step 2 of comparative example 9 had limited catalytic capacity, resulting in a significant decrease in the yield of 2-chloropyrazine.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for synthesizing 2-chloropyrazine, characterized in that: include: The chloroethylene oxide and ethylenediamine are subjected to a cyclization reaction under the conditions of a second catalyst and a second solvent to generate 2-chloropyrazine.

2. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: The second solvent is selected from at least one of ether and alkane; And / or, the second catalyst is selected from at least one of Co-N4 / NC-1000, Co-N4 / NC-1100, Pt / C and Pd / C.

3. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: The second solvent is one of tetrahydrofuran, 2-methyltetrahydrofuran, toluene and xylene; And / or, the second catalyst is at least one of Co-N4 / NC-1000 and Co-N4 / NC-1100.

4. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: The molar ratio of the chloroethylene oxide, ethylenediamine and the second catalyst is 1-2:1:0.01-0.

2.

5. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: In the pre-cyclization reaction liquid, the ratio of the amount of chloroethylene oxide to the volume of the second solvent is 1.1 mol / L to 1.5 mol / L.

6. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: The temperature of the cyclization reaction is 50°C to 200°C; And / or, it also includes a second separation and purification of the liquid after the cyclization reaction, wherein the second separation and purification includes: mixing the liquid after the cyclization reaction with water and then separating the phases, taking the organic phase and evaporating and distilling it under reduced pressure in sequence, collecting the 153°C-154°C fraction, and obtaining the purified 2-chloropyrazine.

7. The method for synthesizing 2-chloropyrazine according to claim 1, characterized in that: Also includes: The vinyl chloride and the oxidant are subjected to oxidation reaction under the conditions of the first catalyst and the first solvent to generate the chloroethylene oxide.

8. The method for synthesizing 2-chloropyrazine according to claim 7, characterized in that: The first solvent is selected from at least one of alcohol and chlorinated hydrocarbon; And / or, the oxidant is selected from at least one of hydrogen peroxide, tert-butyl peroxide and peracetic acid; And / or, the first catalyst is at least one of sodium tungstate, ammonium molybdate and salen cobalt complex.

9. The method for synthesizing 2-chloropyrazine according to claim 8, characterized in that: The oxidation step further comprises at least one of the following: (1) the first solvent is selected from at least one of methanol, ethanol, dichloromethane and dichloroethane; (2) The molar ratio of the vinyl chloride, the first catalyst and the oxidant is 1:0.001-0.1:1-3; (3) The temperature of the oxidation reaction is 0°C to 100°C; (4) The reaction time of the oxidation reaction is 0.5h to 3h; (5) The synthesis method further includes performing a first separation on the liquid after the oxidation reaction, wherein the first separation includes: mixing the liquid after the oxidation reaction with water and then separating the phases, taking the organic phase for evaporation, and obtaining the crude product of chloroethylene oxide.

10. A method for preparing wet electronic chemicals, characterized in that: A method for synthesizing 2-chloropyrazine comprising the method according to any one of claims 1 to 9, wherein the wet electronic chemicals comprise at least one of an etching solution, a stripping solution, a polishing solution and a cleaning solution.

Images