A method for preparing hydrazine hydrate by hydrolysis of benzophenone azine under alkaline conditions

Abstract

The present invention provides a method for preparing hydrazine hydrate by hydrolyzing benzophenone azine under alkaline conditions. The method comprises the following steps: adding an alkaline catalyst to a mixed solution of benzophenone azine, an organic solvent, and water, heating to carry out a hydrolysis reaction, and finally separating the hydrazine hydrate by distillation. The present invention utilizes an alkaline catalyst to promote the hydrolysis reaction, eliminating the need for high-temperature pressurization technology used in traditional processes. It also eliminates process steps such as neutralization, concentration, and desalination, as well as equipment corrosion issues associated with the use of acidic catalysts. The process flow is simple, easy to implement industrially, and has significant economic benefits.

Description

Technical Field

[0001] The invention relates to the field of preparation of hydrazine hydrate, and in particular to a method for preparing hydrazine hydrate by hydrolyzing benzophenone azine. Background Art

[0002] Hydrazine hydrate, also known as hydrated hydrazine, is a colorless, transparent, oily liquid with a faint ammonia odor. It emits smoke in moist air and is highly alkaline and hygroscopic. Industrial applications generally involve 40-80% aqueous hydrazine hydrate solutions. Hydrazine hydrate is an important fine chemical product and a crucial intermediate for pharmaceuticals, pesticides, and dyes. Its derivatives are widely used in many industrial applications, including as reducing agents, antioxidants, and in the production of foaming agents such as AC foaming agent, OBSH foaming agent, and adipic acid dihydrazide. Hydrazine hydrate is also used in the synthesis of high-purity metals, deoxygenation and scale control for boiler feedwater, rocket fuel, and explosives raw materials.

[0003] Hydrazine hydrate production methods primarily include the Raschig process, the urea process, and the ketazine process. The Raschig process has been largely phased out both domestically and internationally due to severe environmental pollution, high equipment investment, and low product yield. Currently, the urea process and the ketazine process are the primary methods used to produce hydrazine hydrate in China. The urea process consumes a lot of energy and produces a large amount of wastewater, while the ketazine process offers the highest yield. Based on development trends, the ketazine process is expected to gradually replace the urea process as the primary method for producing hydrazine hydrate.

[0004] In the traditional ketazine method, acetone azine or butanone azine and water are continuously fed into a distillation column in a specific ratio. Hydrolysis then occurs continuously under high-temperature, pressurized conditions of 150-200°C and 0.7-1.0 MPa for 8-10 hours, yielding approximately 80-90%. However, this technique suffers from high hydrolysis temperatures, high energy consumption, long hydrolysis times, complex process operations, and low safety standards. To prevent distillation column flooding during operation and ensure smooth ketazine hydrolysis, patent CN104961111A proposes a method for reducing distillation column flooding by adding bentonite to the column. However, this technique fails to reduce the operating temperature and pressure of the distillation column and instead introduces the new problem of separating the bentonite from the hydrazine hydrate after the hydrolysis reaction.

[0005] Acidic catalysts such as hydrochloric acid and sulfuric acid can also be used to hydrolyze ketazine to produce hydrazine hydrate. However, the resulting product contains a large amount of hydrazine salts (e.g., hydrazine hydrochloride, hydrazine sulfate, etc.). To obtain pure hydrazine hydrate, a strong base (e.g., sodium hydroxide) must be added to the hydrazine salt solution. Further evaporation, concentration, and desalination processes are required to obtain a highly concentrated hydrazine hydrate solution. Furthermore, hydrolysis under acidic conditions can lead to equipment corrosion, as ordinary carbon steel reactors, pumps, valves, and pipelines are not tolerant to acidic solutions. Patent CN106865513B provides a method for hydrolyzing ketazine to produce hydrazine hydrate under acidic conditions. This method uses hydrazine sulfate as a catalyst at a mass ratio of 5 to 30% of the raw material. Hydrazine hydrate is distilled from the top of the column at a temperature range of 110 to 120°C. Although the catalyst can reduce the operating temperature and pressure of the distillation column, the large amount of catalyst added affects production efficiency and can lead to equipment corrosion. Summary of the Invention

[0006] In response to the deficiencies of the prior art, the present invention provides a method for preparing hydrazine hydrate by hydrolyzing ketazine under alkaline conditions. An alkaline catalyst is used during the hydrolysis process, and no hydrazine salt is produced. There is no corrosion to reaction equipment, pipelines, or valves. After the hydrolysis is completed, no neutralization reaction is required, and hydrazine hydrate can be directly obtained in a high yield.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing hydrazine hydrate by hydrolysis of benzophenone azine under alkaline conditions comprises the following steps:

[0009] (1) Add 30 parts of benzophenone azide to a reaction flask, add 100-150 parts of solvent, and stir evenly;

[0010] (2) adding 10-15 parts of distilled water and 10-15 parts of an alkaline catalyst to a reaction flask, venting the reaction flask with nitrogen for protection, and connecting a condenser for reflux; the alkaline catalyst is one of tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and phenyltrimethylammonium hydroxide;

[0011] (3) Heat the reaction flask to 80-100°C and continue stirring for 6-8 hours;

[0012] (4) replacing the condenser with a fractionating column, distilling and receiving the 110-120° C. fraction to obtain hydrazine hydrate;

[0013] The above parts are all parts by weight.

[0014] Preferably, the solvent in step (1) is one of dimethyl sulfoxide (DMSO), ethylene glycol dimethyl ether, and dioxane.

[0015] Preferably, in step (3), the temperature is raised to 95-100° C. and the reaction is continuously stirred for 6-8 hours.

[0016] Compared with the prior art, the present invention has the following advantages: it utilizes an alkaline catalyst to promote the hydrolysis reaction, eliminating the need for high-temperature pressurization technology required in traditional processes and eliminating the process steps of neutralization, concentration, and desalination required by the use of acidic catalysts. The process flow is simple, easy to implement industrially, and has significant economic benefits. The method for preparing hydrazine hydrate by hydrolyzing ketazine under alkaline conditions described in the present invention has the advantages of not generating hydrazine salts, causing no corrosion to reaction equipment, pipelines, and valves, and providing a high yield of hydrazine hydrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The hydrazine hydrate prepared in Example 1 1 H NMR spectrum. DETAILED DESCRIPTION

[0018] The technical solution of the present invention is further described in detail below through specific implementation methods. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments, and the scope of protection of the present invention is not limited thereto. Based on the embodiments of the present invention, other embodiments obtained by ordinary technicians in this field without making creative work are all within the scope of protection of the present invention.

[0019] In an embodiment of the present invention, the steps for preparing hydrazine hydrate by hydrolysis of benzophenone azine under alkaline conditions are as follows:

[0020] (1) Add 30 parts of benzophenone azide to a reaction flask, add 100-150 parts of solvent, and stir evenly; then add 10-15 parts of distilled water and 10-15 parts of alkaline catalyst to the reaction flask.

[0021] (2) The reaction flask was protected by nitrogen, and the temperature was raised to 80-100°C. A condenser was connected to reflux, and the reaction was stirred continuously for 6-8 hours;

[0022] (3) The condenser is replaced with a fractionating column, and the fraction at 110-120° C. is distilled to obtain hydrazine hydrate.

[0023] The solvent in step (1) is one of dimethyl sulfoxide (DMSO), ethylene glycol dimethyl ether, and dioxane, and the alkaline catalyst is one of tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and phenyltrimethylammonium hydroxide.

[0024] The characterization test method in the embodiment of the present invention is as follows:

[0025] 1) Determination of hydrazine hydrate yield (Y.%)

[0026] Y.%=m1 / m2×100%

[0027] In the above formula, m1 is the mass of the distilled hydrazine hydrate, and m2 is the theoretical maximum mass of the hydrazine hydrate calculated based on the amount of benzophenone azine added.

[0028] 2) H NMR spectrum of hydrazine hydrate ( 1 H NMR) determination

[0029] The distilled hydrazine hydrate was dissolved in deuterated DMSO and analyzed on a Bruker Avance III 500 MHz nuclear magnetic resonance spectrometer (NMR). 1 H NMR measurement was performed at room temperature.

[0030] Example 1

[0031] To a 250mL three-necked flask, 30.0g of benzophenone azide, 100.0g of dimethyl sulfoxide (DMSO), 15.0g of distilled water, 10.0g of tetrabutylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with nitrogen protection at normal pressure. The three-necked flask was placed in an oil bath and heated at 100°C. After stirring for 8 hours, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and a 110-120°C fraction was received to obtain 3.66g of hydrazine hydrate with a yield of 87.9%. The obtained hydrazine hydrate was subjected to 1 H NMR test, the results are as attached Figure 1 shown.

[0032] Example 2

[0033] To a 250mL three-necked flask, 30.0g of benzophenone azide, 150.0g of ethylene glycol dimethyl ether, 10.0g of distilled water, 15.0g of benzyltrimethylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with nitrogen gas at atmospheric pressure. The three-necked flask was placed in an oil bath and heated at 80°C. After stirring for 6h, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and a 110-120°C fraction was received to obtain 2.72g of hydrazine hydrate with a yield of 65.3%.

[0034] Example 3

[0035] To a 250mL three-necked flask, 30.0g of benzophenone azide, 130.0g of dioxane, 12.0g of distilled water, 13.0g of phenyltrimethylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with nitrogen gas at atmospheric pressure. The three-necked flask was heated in an oil bath at 95°C. After stirring for 8h, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and the 110-120°C fraction was collected to obtain 3.42g of hydrazine hydrate with a yield of 82.1%.

[0036] Example 4

[0037] To a 250mL three-necked flask, 30.0g of benzophenone azide, 120.0g of dimethyl sulfoxide (DMSO), 12.0g of distilled water, 15.0g of benzyltrimethylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with nitrogen gas at atmospheric pressure. The three-necked flask was placed in an oil bath and heated at 100°C. After stirring for 8h, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and the 110-120°C fraction was collected to obtain 3.52g of hydrazine hydrate with a yield of 84.5%.

[0038] Example 5

[0039] To a 250mL three-necked flask, 30.0g of benzophenone azide, 120.0g of ethylene glycol dimethyl ether, 15.0g of distilled water, 15.0g of tetrabutylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with nitrogen gas at atmospheric pressure. The three-necked flask was heated in an oil bath at 80°C. After stirring for 7h, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and the 110-120°C fraction was collected to obtain 3.11g of hydrazine hydrate with a yield of 74.6%.

[0040] Example 6

[0041] To a 250mL three-necked flask, 30.0g of benzophenone azide, 150.0g of dimethyl sulfoxide (DMSO), 10.0g of distilled water, 15.0g of phenyltrimethylammonium hydroxide, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser tube was connected. The condenser tube was terminated with a nitrogen atmosphere at atmospheric pressure. The three-necked flask was placed in an oil bath and heated at 100°C. The reaction was stirred for 6h, and then the condenser tube was replaced with a thorn-shaped fractionating column. The mixture was heated and distilled to a 110-120°C fraction to obtain 3.37g of hydrazine hydrate with a yield of 80.9%.

[0042] Comparative Example (Hydrolysis under Acidic Conditions)

[0043] To a 250mL three-necked flask, 30.0g of benzophenone azide, 150.0g of dioxane, 10.0g of distilled water, 15.0g of 732# strongly acidic cation exchange resin, and a magnetic stirrer were added. A thermometer was inserted into the three-necked flask, and a condenser was connected. The condenser was terminated with atmospheric nitrogen protection. The three-necked flask was placed in an oil bath and heated at 95°C. After stirring for 8h, the condenser was replaced with a thorn-shaped fractionating column, heated and distilled, and the 110-120°C fraction was collected to obtain 1.78g of hydrazine hydrate with a yield of 42.7%.

Claims

1. A method for preparing hydrazine hydrate by hydrolysis of benzophenone azine under alkaline conditions, characterized in that: The method comprises the following steps: (1) Add 30 parts of benzophenone azide to a reaction flask, add 100-150 parts of solvent, and stir evenly; (2) adding 10-15 parts of distilled water and 10-15 parts of an alkaline catalyst to a reaction flask, venting the reaction flask with nitrogen for protection, and connecting a condenser for reflux; the alkaline catalyst is one of tetrabutylammonium hydroxide, benzyltrimethylammonium hydroxide, and phenyltrimethylammonium hydroxide; (3) Heat the reaction flask to 80-100°C and continue stirring for 6-8 hours; (4) replacing the condenser with a fractionating column, distilling and receiving the 110-120° C. fraction to obtain hydrazine hydrate; The above parts are all parts by weight.

2. The method according to claim 1, wherein: The solvent in step (1) is one of dimethyl sulfoxide, ethylene glycol dimethyl ether and dioxane.

3. The method according to claim 1, wherein: In step (3), the temperature is raised to 95-100° C. and the reaction is stirred continuously for 6-8 hours.

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