A green synthesis process for high-content acetic hydrazide

Abstract

The present invention relates to the technical field of organic synthesis, and in particular to a green synthesis process of high-content acetohydrazide. The present invention uses a one-pot method to heat ethyl acetate and hydrazine hydrate under the action of a catalyst, and then distills them at different temperatures to gradually remove various impurities in the crude product, and finally prepares acetohydrazide. The one-pot method reduces the intermediate steps and the separation and purification steps of the product, which helps to maintain a higher raw material conversion rate and product yield; multiple re-distillations can improve the impurity removal rate, and directly distilling acetohydrazide from the reaction system can reduce the loss of materials, and there is no need to transfer the product to another container for separation, which can improve the overall yield and product purity. The acetohydrazide prepared in the present invention has an extremely high yield, extremely high purity and a simple process, which greatly saves production costs and labor costs, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of organic synthesis, in particular to a green synthesis process of high-content acetic hydrazide. Background Art

[0002] Acetylhydrazine is a white crystal with a melting point of 58-68℃. It is easily soluble in water and is an important chemical raw material. It can be used to synthesize analgesics, anticancer drugs, tooth corrosion inhibitors, platelet activity index inhibitors, antifogging agents and stabilizers for color fixers, metal pickling preservatives, etc. In particular, the use of acetylhydrazine as a raw material to prepare carbamate insecticides can avoid the toxicity to the human body and the environment caused by the direct use of methyl isocyanate.

[0003] At present, the synthesis method of acetic acid hydrazide is generally prepared by using acetic acid, ethanol and hydrazine hydrate as raw materials through two-step reaction: the first step is to use acetic acid and ethanol to carry out esterification reaction under the action of concentrated sulfuric acid catalyst to generate ethyl acetate, and the second step is to heat ethyl acetate and hydrazine hydrate in ethanol solvent for hydrazine hydrolysis reaction to obtain acetic acid hydrazide. The method for synthesizing acetic acid hydrazide has the following disadvantages: in the first step of esterification reaction, the catalyst concentrated sulfuric acid used is highly corrosive, has high requirements for equipment, and will produce a large amount of acidic organic wastewater. After the wastewater is neutralized with alkali, the salt content and COD content are very high. Due to the difficulty of organic wastewater treatment, high treatment cost and large discharge volume, it is easy to cause environmental pollution; the two-step reaction synthesis of acetic acid hydrazide also has many operation steps, cumbersome process, complex process, high energy consumption, many side reaction impurities, low total yield, high production cost and other problems.

[0004] In the optimization of the general synthesis method of acetylhydrazine, patent technology document CN115466197A discloses a synthesis method of acetylhydrazine, comprising the following steps: adding hydrazine hydrate to a reactor, adding ethanol, then adding ethyl acetate, and then heating under nitrogen protection for reflux reaction; after the reaction, vacuum distillation, distillation until no liquid flows out, adding acetonitrile to continue azeotropic distillation, then adding tetrahydrofuran to continue azeotropic distillation, then adding tetrahydrofuran and acetonitrile, dissolving; stirring, filtering; finally washing the filter cake with cold tetrahydrofuran, and vacuum drying the obtained filter cake to obtain acetylhydrazine. This invention avoids the use of high concentrations of hydrazine hydrate, reducing potential hazards to operators and the environment, but the synthesis involves multiple azeotropic distillations, the process is complicated, and the production cost is high.

[0005] Therefore, according to the above-mentioned related technologies, it is urgent to develop a green synthesis process for high-content acetylhydrazine with simple process, high purity and high yield. Summary of the invention

[0006] In view of this, the purpose of the present invention is to propose a green synthesis process for high-content acetic hydrazide, so as to provide a green synthesis process for high-content acetic hydrazide with simple process, high purity and high yield.

[0007] Based on the above purpose, the present invention provides a green synthesis process of high-content acetic hydrazide.

[0008] A green synthesis process for high-content acetic hydrazide, comprising a reaction system and a purification system;

[0009] The reaction system includes a three-necked flask used, the three-necked flask includes a first feed port and a second feed port and a third feed port respectively located on both sides thereof, wherein a condenser is provided above the second feed port and the third feed port through a rubber tube, and a hemostatic clamp is provided between the second feed port and the condenser, and a hemostatic clamp is provided between the third feed port and the condenser;

[0010] The synthesis process comprises the following steps:

[0011] Step S1. Under nitrogen protection, close the hemostatic clamp on the second feed port and the hemostatic clamp on the third feed port in sequence, put hydrazine hydrate, ethyl acetate and a catalyst into a flask in sequence, heat and stir to obtain a mixture A;

[0012] Step S2. Open the hemostatic clamp on one side of the second feed port, heat and stir the mixture A, and change the system temperature to T1 until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0013] Step S3. Change the system temperature to T2 and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0014] Step S4. Close the hemostatic clamp on the side of the second feed inlet, open the hemostatic clamp on the side of the third feed inlet, change the system temperature to T3 again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine;

[0015] The molar ratio of hydrazine hydrate, ethyl acetate and catalyst in step S1 is 0.2:0.25-0.27:0.016-0.03.

[0016] Preferably, the catalyst in step S1 is a mixture of HY-type solid acid molecular sieve and EDCl. The HY-type solid acid molecular sieve can adsorb water molecules in the product in its pores and has good thermal stability. EDCl is a good catalyst in organic synthesis and is soluble in the by-product ethanol, which is conducive to the forward progress of the reaction.

[0017] Preferably, the mixture is obtained by mixing HY type solid acid molecular sieve and EDCl in a molar ratio of 3-4:1.

[0018] Preferably, the hydrazine hydrate in step S1 is hydrazine hydrate with a mass fraction of 80%, avoiding the use of high-concentration hydrazine hydrate to ensure experimental safety and economic benefits.

[0019] Preferably, the temperature during heating and stirring in step S1 is 58-63° C. and the stirring time is 3.5-4.5 h.

[0020] Preferably, the temperature T1 in step S2 is 98-103° C., and the byproducts ethanol and water in the mixture A, the EDCl in the catalyst, and the incompletely reacted ethyl acetate are removed.

[0021] Preferably, the temperature T2 in step S3 is 120-123° C. to remove the unreacted hydrazine hydrate in the solution.

[0022] Preferably, the temperature T3 in step S4 is 129-135° C., the product acetylhydrazine is evaporated from the reaction system, and acetylhydrazine and the HY type solid acid molecular sieve catalyst are separated.

[0023] Beneficial effects of the present invention:

[0024] The present invention provides a green synthesis process of high-content acetohydrazide. The present invention uses a one-pot method to heat ethyl acetate and hydrazine hydrate under the action of a catalyst, and then distills them at three different temperatures respectively, gradually removes various impurities in the crude product, and finally prepares acetohydrazide. The one-pot method reduces the intermediate steps and the separation and purification steps of the product, which helps to maintain a higher raw material conversion rate and product yield; multiple re-distillations can improve the impurity removal rate, and directly distilling the product from the reaction system can reduce the loss of materials to improve the overall yield and product purity, so that the prepared acetohydrazide has an extremely high yield, an extremely high purity and a simple process, which greatly saves production costs and labor costs, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 is a flow chart for the preparation of acetic hydrazide in the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of a three-necked flask in the reaction system of the present invention;

[0028] Description of reference numerals: 1, first feed inlet; 2, second feed inlet; 3, third feed inlet;

[0029] Figure 3 For the acetylhydrazine prepared in Example 2 of the present invention 1H NMR spectrum. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0031] The sources and properties of some of the raw materials used in the present invention are as follows:

[0032] Ethyl acetate was purchased from Shandong Ruishuang Chemical Co., Ltd.; 80% by mass hydrazine hydrate was purchased from Huangshan Bashui Chemical Additive Co., Ltd.; EDCl was purchased from Shanghai Maokang Biotechnology Co., Ltd.; HY type solid acid molecular sieve was purchased from Dalian Zhuoran Environmental Protection Technology Co., Ltd.

[0033] Embodiment 1:

[0034] A green synthesis process for high-content acetic hydrazide, comprising a reaction system and a purification system;

[0035] The reaction system includes a three-necked flask used, which includes a first feed port 1 and a second feed port 2 and a third feed port 3 respectively located on both sides thereof, wherein a condenser is arranged above the second feed port 2 and the third feed port 3 through a rubber tube, and a hemostatic clamp is arranged between the second feed port 2 and the condenser, and a hemostatic clamp is arranged between the third feed port 3 and the condenser.

[0036] Embodiment 2: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0037] S1. Under nitrogen protection, close the hemostatic clamp on the side of the second feed port 2 and the hemostatic clamp on the side of the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol) into the flask in turn, heat and stir at 58°C for 4.5 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 3:1;

[0038] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 98 ° C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0039] S3. Change the system temperature to 120°C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0040] S4. Close the hemostatic clamp on the second feed port 2, open the hemostatic clamp on the third feed port 3, change the system temperature to 129 ° C again, stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, and obtain acetyl hydrazine;

[0041] Depend on Figure 3 of 1 The H NMR spectrum showed that acetylhydrazine was successfully synthesized.

[0042] Embodiment 3: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0043] S1. Under nitrogen protection, close the hemostatic clamps on the second feed port 2 and the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and a catalyst (0.018 mol) into a flask in turn, heat and stir at 59°C for 4.5 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 3:1;

[0044] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 99°C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0045] S3. Change the system temperature to 121 ° C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0046] S4. Close the hemostatic clamp on the side of the second feed port 2, open the hemostatic clamp on the side of the third feed port 3, change the system temperature to 130° C. again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine.

[0047] Embodiment 4: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0048] S1. Under nitrogen protection, close the hemostatic clamps on the second feed port 2 and the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.91 g, 0.26 mol), and a catalyst (0.02 mol) into a flask in turn, heat and stir at 60°C for 4 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 3.5:1;

[0049] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 100 ° C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0050] S3. Change the system temperature to 121 ° C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0051] S4. Close the hemostatic clamp on the side of the second feed port 2, open the hemostatic clamp on the side of the third feed port 3, change the system temperature to 132° C. again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine.

[0052] Embodiment 5: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0053] S1. Under nitrogen protection, close the hemostatic clamps on the second feed port 2 and the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.91 g, 0.26 mol), and a catalyst (0.024 mol) into a flask in turn, heat and stir at 61°C for 4 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 3.5:1;

[0054] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 101°C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0055] S3. Change the system temperature to 122°C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0056] S4. Close the hemostatic clamp on the side of the second feed port 2, open the hemostatic clamp on the side of the third feed port 3, change the system temperature to 133° C. again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine.

[0057] Embodiment 6: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0058] S1. Under nitrogen protection, close the hemostatic clamps on the second feed port 2 and the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (23.79 g, 0.27 mol), and a catalyst (0.028 mol) into a flask in turn, heat and stir at 62°C for 3.5 h to obtain a mixture A, wherein the molar ratio of HY-type solid acid molecular sieve to EDCl in the catalyst is 4:1;

[0059] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 102 ° C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0060] S3. Change the system temperature to 122°C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0061] S4. Close the hemostatic clamp on the side of the second feed port 2, open the hemostatic clamp on the side of the third feed port 3, change the system temperature to 134° C. again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine.

[0062] Embodiment 7: A green synthesis process of high-content acetic hydrazide, comprising the following steps:

[0063] S1. Under nitrogen protection, close the hemostatic clamp on the side of the second feed port 2 and the hemostatic clamp on the side of the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (23.79 g, 0.27 mol), and catalyst (0.03 mol) into the flask in turn, heat and stir at 63°C for 3.5 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 4:1;

[0064] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, and change the system temperature to 103 ° C until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0065] S3. Change the system temperature to 123°C and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises;

[0066] S4. Close the hemostatic clamp on the side of the second feed port 2, open the hemostatic clamp on the side of the third feed port 3, change the system temperature to 135° C. again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine.

[0067] Comparative Example 1:

[0068] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (5.01 g, 0.1 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0069] Comparative Example 2:

[0070] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (13.22 g, 0.15 mol), and catalyst (0.016 mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0071] Comparative Example 3:

[0072] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.01 mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0073] Comparative Example 4:

[0074] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (15.02 g, 0.3 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0075] Comparative Example 5:

[0076] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (35.25 g, 0.4 mol), and catalyst (0.016 mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0077] Comparative Example 6:

[0078] Compared with Example 2, this comparative example only adjusts "hydrazine hydrate (10.01g, 0.2mol) with a mass fraction of 80%, ethyl acetate (22.03g, 0.25mol), and catalyst (0.016mol)" to "hydrazine hydrate (10.01g, 0.2mol) with a mass fraction of 80%, ethyl acetate (22.03g, 0.25mol), and catalyst (0.1mol)", and the remaining steps and parameters are the same, and this comparative example will not be repeated, and acetohydrazide is finally obtained.

[0079] Comparative Example 7:

[0080] S1. Under nitrogen protection, close the hemostatic clamps on the second feed port 2 and the third feed port 3 in turn, put hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and a catalyst (0.016 mol) into a flask in turn, heat and stir at 58°C for 4.5 h to obtain a mixture A, wherein the molar ratio of HY type solid acid molecular sieve to EDCl in the catalyst is 3:1;

[0081] S2. Open the hemostatic clamp on the second feed port 2, heat and stir the mixture A, change the system temperature to 120°C, until the water level in the receiving container at the outlet of the condenser tube no longer rises, to obtain a mixture B;

[0082] S3. Pour out the mixture B while it is hot and filter it. The filtrate is cooled, crystallized, washed with pure water and vacuum dried to obtain acetylhydrazine.

[0083] Comparative Example 8:

[0084] Compared with Example 2, this comparative example only replaces "hydrazine hydrate with a mass fraction of 80%" with "hydrazine hydrate with a mass fraction of 40%", and the remaining steps and parameters are the same, which will not be repeated in this comparative example, and acetylhydrazine is finally obtained.

[0085] Performance Test:

[0086] Yield:

[0087] First, the theoretical yield is calculated, that is, the mass of the product when the reaction is completely converted, and then the acethydrazide prepared in Example 2 to Example 7 and Comparative Example 1 to Comparative Example 8 is slowly evaporated and crystallized at 58° C., and the mass of the acethydrazide actually obtained is weighed;

[0088] Yield calculation formula:

[0089] Yield = (actual yield / theoretical yield) × 100%

[0090] purity:

[0091] Accurately weigh 5g of the acethydrazide prepared in Example 2-Example 7 and Comparative Example 1-Comparative Example 8 respectively, and dissolve it in chloroform. Prepare a series of acethydrazide standard solutions of known concentrations, and analyze these solutions by HPLC to construct a standard curve. Again the acethydrazide solution prepared in Example 2-Example 7 to be measured and Comparative Example 1-Comparative Example 8 is injected into the HPLC system for analysis, the chromatogram of acethydrazide to be measured is recorded and compared with the standard curve, and the concentration of the acethydrazide prepared in Example 2-Example 7 and Comparative Example 1-Comparative Example 8 is calculated respectively.

[0092] Purity calculation formula:

[0093] Purity = (actual measured concentration / theoretical concentration) × 100%

[0094] Table 1 Summary of the amount of raw materials used in Examples 2 to 7 and Comparative Examples 1 to 8

[0095] project Amount of hydrazine hydrate / mol Amount of ethyl acetate / mol Catalyst dosage / mol Example 2 0.2 0.25 0.016 Example 3 0.2 0.25 0.018 Example 4 0.2 0.26 0.02 Example 5 0.2 0.26 0.024 Example 6 0.2 0.27 0.028 Example 7 0.2 0.27 0.03 Comparative Example 1 0.1 0.25 0.016 Comparative Example 2 0.2 0.15 0.016 Comparative Example 3 0.2 0.25 0.01 Comparative Example 4 0.3 0.25 0.016 Comparative Example 5 0.2 0.4 0.016 Comparative Example 6 0.2 0.25 0.1 Comparative Example 7 0.2 0.25 0.016 Comparative Example 8 0.2 0.25 0.016

[0096] Table 2 Summary of experimental data in Examples 2 to 7 and Comparative Examples 1 to 8

[0097] project Yield / % purity / % Example 2 99.1 99.0 Example 3 99.2 99.1 Example 4 99.5 99.4 Example 5 99.5 99.4 Example 6 99.3 99.3 Example 7 99.0 99.1 Comparative Example 1 96.5 96.4 Comparative Example 2 97.0 97.0 Comparative Example 3 96.6 96.7 Comparative Example 4 98.2 98.1 Comparative Example 5 98.1 97.9 Comparative Example 6 97.8 97.5 Comparative Example 7 97.2 96.3 Comparative Example 8 97.6 97.3

[0098] Data Analysis:

[0099] As can be seen from Table 2, the acetylhydrazine prepared by the present invention has a higher yield and purity and a simple process, which may be due to the one-pot method adopted in the present invention, which reduces the intermediate steps and the separation and purification steps of the product, improves the overall synthesis efficiency, and helps to maintain a higher raw material conversion rate and product yield; the catalyst used in the present invention is a mixture of HY type solid acid molecular sieve and EDCl, wherein the HY type solid acid molecular sieve can adsorb byproduct water molecules in its pores and has good thermal stability, which is conducive to the forward reaction, and EDCl is easily soluble in the byproduct ethanol, which may help it to more effectively adsorb reaction intermediates, reduce the reaction energy barrier, accelerate the rate of the forward reaction, and reduce the generation of byproducts, which is also conducive to the forward reaction, so that the yield of the acetylhydrazine finally prepared is as high as 99.5%; and the present invention performs distillation at three different temperatures, gradually removes various impurities in the crude product and directly distills the product from the reaction system, the process is simple and the impurity removal rate is high, so that the purity of the acetylhydrazine finally prepared is as high as 99.4%.

[0100] In Comparative Example 1, since "80% hydrazine hydrate (10.01 g, 0.2 mol), ethyl acetate (22.03 g, 0.25 mol), catalyst (0.016 mol)" is adjusted to "80% hydrazine hydrate (5.01 g, 0.1 mol), ethyl acetate (22.03 g, 0.25 mol), catalyst (0.016 mol)", it can be seen from Table 2 that the yield and purity of acetylhydrazine prepared by this method are low, which may be due to the fact that the amount of hydrazine hydrate is too small. The theoretical amount of ethyl acetate and hydrazine hydrate is 1:1, but in the experiment, the amount of one raw material is usually increased appropriately so that the other raw material can react. Complete, thereby improving the yield, the amount of ethyl acetate and the catalyst that have not reacted is relatively excessive, resulting in a decrease in purity, so the yield and purity of Comparative Example 1 are worse than those of Example 2; Comparative Example 2 adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (13.22 g, 0.15 mol), and catalyst (0.016 mol)", and it can be seen from Table 2 that the yield and purity of acetyl hydrazine prepared by this method are low, which may be due to The amount of ethyl acetate used is too small, so the yield is reduced, and the purity of the product in the reaction system decreases. Therefore, the yield and purity of Comparative Example 2 are worse than those of Example 2; Comparative Example 3 adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.01 mol)". It can be seen from Table 2 that the yield and purity of acetyl hydrazine prepared by this method are low, which may be due to the use of the catalyst. If the amount is too small, it may be adsorbed by the reactants or products, and the active sites of the catalyst may be quickly saturated, causing the catalyst to lose activity and fail to play a catalytic role, thereby reducing the yield, and the amount of raw materials not participating in the reaction in the reaction system increases. Therefore, the yield and purity of Comparative Example 3 are worse than those of Example 2; Comparative Example 4 adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (15.02 g, 0.3 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016mol)", it can be seen from Table 2 that the yield and purity of acetylhydrazine prepared by the method are low, which may be due to the excessive amount of hydrazine hydrate used, which will cause unnecessary waste, increase production costs, and is not easy to separate and purify, so the yield and purity of Comparative Example 4 are worse than those of Example 2; Comparative Example 5 adjusts "hydrazine hydrate (10.01g, 0.2mol) with a mass fraction of 80%, ethyl acetate (22.03g, 0.25mol), and catalyst (0.016mol)" to "hydrazine hydrate (10.01g, 0.2mol) with a mass fraction of 80%, ethyl acetate (35.25g, 0.4mol), and catalyst (0.016mol)", from Table 2 It can be seen that the yield and purity of acetylhydrazine prepared by the method are low. This may be due to the excessive amount of ethyl acetate, which is not easy to separate and purify and may affect the direction of the reaction, reducing the yield of acetylhydrazine. Therefore, the yield and purity of Comparative Example 5 are worse than those of Example 2; Comparative Example 6 adjusts "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.016 mol)" to "hydrazine hydrate (10.01 g, 0.2 mol) with a mass fraction of 80%, ethyl acetate (22.03 g, 0.25 mol), and catalyst (0.1 mol)". It can be seen from Table 2 that the method prepared The yield and purity of acetylhydrazine are low, which may be due to excessive catalyst dosage. Excessive catalyst may cause aggregation or sedimentation between catalysts, thereby reducing the total specific surface area of ​​the catalyst, reducing the effective contact area between the catalyst and the reactant, resulting in a decrease in catalytic efficiency and difficulty in separation and purification, thereby reducing the yield and purity. Therefore, the yield and purity of Comparative Example 6 are worse than those of Example 2; Comparative Example 7 does not undergo multiple re-distillation separation and purification. It can be seen from Table 2 that the yield and purity of acetylhydrazine prepared by this method are low. This may be due to the fact that multiple re-distillations can effectively remove impurities in the system, and by utilizing the difference in vapor-liquid equilibrium of different substances at different temperatures, pure acetylhydrazine is gradually separated, thereby improving the purity of acetylhydrazine. , and directly distilling from the reaction system can reduce material loss, and there is no need to transfer the product to another container for separation, thereby improving the overall yield. Therefore, the yield and purity of Comparative Example 7 are worse than those of Example 2; Comparative Example 8 replaces "hydrazine hydrate with a mass fraction of 80%" with "hydrazine hydrate with a mass fraction of 40%". It can be seen from Table 2 that the yield and purity of acetylhydrazine prepared by this method are lower. This may be because the lower concentration of hydrazine hydrate reduces the concentration of effective reactants, resulting in a decrease in the reaction rate, which may require a longer reaction time or a higher temperature to achieve the same conversion rate, thereby affecting the yield and purity of the reaction. Therefore, the yield and purity of Comparative Example 8 are worse than those of Example 2. .

[0101] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present invention is limited to these examples. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0102] The present invention is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A green synthesis process for high-content acetic hydrazide, characterized in that, Including reaction system and purification system; The reaction system comprises a three-necked flask used, wherein the three-necked flask comprises a first feed port (1) and a second feed port (2) and a third feed port (3) respectively located on both sides thereof, wherein a condenser is arranged above the second feed port (2) and the third feed port (3) through a rubber tube, and a hemostatic clamp is arranged between the second feed port (2) and the condenser, and a hemostatic clamp is arranged between the third feed port (3) and the condenser; The synthesis process comprises the following steps: Step S1. Under nitrogen protection, close the hemostatic clamp on one side of the second feed port (2) and the hemostatic clamp on one side of the third feed port (3) in sequence, put hydrazine hydrate, ethyl acetate and a catalyst into a flask in sequence, heat and stir to obtain a mixture A; Step S2. Open the hemostatic clamp on one side of the second feed port (2), heat and stir the mixture A, and change the system temperature to T1 until the water level in the receiving container at the outlet of the condenser tube no longer rises; Step S3. Change the system temperature to T2 and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises; Step S4. Close the hemostatic clamp on one side of the second feed port (2), open the hemostatic clamp on one side of the third feed port (3), change the system temperature to T3 again, and stir evenly until the water level in the receiving container at the outlet of the condenser tube no longer rises, thereby obtaining acetylhydrazine; The molar ratio of hydrazine hydrate, ethyl acetate and catalyst in step S1 is 0.2:0.25-0.27:0.016-0.03; The temperature T1 in step S2 is 98-103°C; The temperature T2 in step S3 is 120-123°C; The temperature T3 in step S4 is 129-135°C; The catalyst in step S1 is a mixture of HY type solid acid molecular sieve and EDCl; The mixture is obtained by mixing HY type solid acid molecular sieve and EDCl in a molar ratio of 3-4:

1.

2. The green synthesis process of high-content acetic hydrazide according to claim 1, characterized in that, The hydrazine hydrate in step S1 is hydrazine hydrate with a mass fraction of 80%.

3. The green synthesis process of high-content acetic hydrazide according to claim 1, characterized in that, The temperature during heating and stirring in step S1 is 58-63° C. and the stirring time is 3.5-4.5 h.

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