A simple and high-yield method for synthesizing o-aminophenol

Abstract

The application discloses a simple and high-yield o-aminophenol synthesis method, and the synthesis route of the method is as follows: taking sodium o-nitrophenol as raw material, H2 as a reducing agent, Pd / C as a catalyst, and heating and reacting; after the reaction is completed, the reaction liquid is filtered, a certain amount of sulfourea dioxide is added into the filtrate, hydrochloric acid is used to adjust the PH to 3, and then the target product o-aminophenol is obtained by filtering. In the application, the palladium-carbon is used as the catalyst, the reaction condition is mild, the side reaction is less, and the post-treatment is simple. The palladium-carbon catalyst is easy to obtain, stable in structure, easy to separate, can be recycled and utilized, and is easy to regenerate after deactivation, and the cost is lower. After the reaction is completed, the sulfourea dioxide is added into the reaction liquid, which can not only consume oxygen in advance, prevent the product from being oxidized, but also inhibit the colored oxidation byproduct, and prevent the system from turning yellow. Meanwhile, the sulfourea dioxide is low in toxicity, and is used as an antioxidant, which is less in three wastes and easy to handle wastewater. The method has the advantages of simple operation, low cost, high product yield, environmental friendliness and the like, is suitable for large-scale production, and has certain industrialization prospect.

Description

Technical Field

[0001] This invention belongs to the field of organic chemical synthesis technology, specifically relating to a simple and high-yield method for synthesizing o-aminophenol. Background Technology

[0002] o-Aminophenol is an important chemical intermediate widely used in dyes, pharmaceuticals, and printing. Traditional synthesis methods have significant drawbacks. For example, Chinese patent CN100391922C reports a method for obtaining o-aminophenol from o-nitrochlorobenzene via hydrolysis and sodium sulfide reduction. This method has a yield of approximately 88-90%, but generates a large amount of waste, causing serious environmental pollution. Chinese patent CN101514697A uses iron powder instead of sodium sulfide to reduce o-aminophenol. While this method reduces sulfur pollution, the resulting product is encased in iron sludge, and the process of removing the sludge is cumbersome, resulting in a low yield of only about 85%. Chinese patent CN113101974A uses a composite catalyst, which is free of precious metals and has low cost; however, the catalyst's resistance to poisoning is generally low, and the raw materials require refining. Chinese patent publication CN114181098A reports the reduction of o-nitrophenol to o-aminophenol using o-nitrophenol as a raw material, ethanol and water as solvents, and Raney nickel as a catalyst. This method has low production costs and produces less waste. However, Raney nickel catalyst is prone to spontaneous combustion and deactivation, and ethanol organic solvent is flammable and volatile, making it more dangerous in comparison.

[0003] Therefore, it is of great significance to develop a simple and high-yield method for the synthesis of o-aminophenol. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a simple and high-yield method for synthesizing o-aminophenol. This method is simple to operate, low in cost, has a high product yield, is environmentally friendly, and is suitable for large-scale production.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] This invention provides a simple and high-yield method for synthesizing o-aminophenol, the synthetic route of which is as follows:

[0007]

[0008] The specific synthesis steps are as follows:

[0009] S1. Using sodium o-nitrophenolate as raw material, a certain amount of water is added, H2 is used as a reducing agent, Pd / C is used as a catalyst, and the temperature is raised to react;

[0010] S2. Filter the reaction solution obtained in S1, add a certain amount of thiourea dioxide to the filtrate, adjust the pH to 3 with hydrochloric acid, stir for a period of time, filter, and obtain the target product o-aminophenol.

[0011] Preferably, in step S1, the H2 pressure is 0.6~1.0MPa, the reaction temperature is 70~100℃, and the reaction time is 5~10h.

[0012] Preferably, in step S1, the Pd / C has a palladium content of 5% and a water content of 50%.

[0013] Preferably, in step S1, the mass ratio of sodium o-nitrophenolate to Pd / C is 1: (0.002~0.01).

[0014] Preferably, in step S2, the mass ratio of sodium o-nitrophenolate and thiourea dioxide is 1:(0.008~0.02).

[0015] Preferably, in step S2, the molar concentration of the hydrochloric acid is 2-4 mol / L.

[0016] Preferably, in step S2, the acidification process of adjusting the pH with hydrochloric acid needs to be carried out at 10~-10℃.

[0017] Preferably, in step S2, the pH adjustment acidification process with hydrochloric acid requires stirring for 2-4 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention uses palladium on carbon as a catalyst, resulting in mild reaction conditions, few side reactions, and simple post-processing. Palladium on carbon catalysts are readily available, structurally stable, easily separated, and recyclable. Regeneration after deactivation is also simple and cost-effective. It can be recycled more than five times without significant decrease in activity.

[0020] This invention features a rationally designed post-treatment purification process, simplifying the operation. In this invention, adding thiourea dioxide to the reaction solution after the reaction not only consumes oxygen in advance, preventing product oxidation, but also inhibits colored oxidation byproducts, preventing the system from turning yellow. Simultaneously, thiourea dioxide is low in toxicity, and its use as an antioxidant results in less wastewater and easier treatment, reducing environmental pollution and aligning with green chemistry principles. Furthermore, this method offers advantages such as simple operation, low cost, and environmental friendliness, making it suitable for industrial-scale production. Detailed Implementation

[0021] The preferred embodiments of the present invention are described below. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0022] Example 1: Preparation of o-aminophenol.

[0023] Dissolve 120.0 g of sodium o-nitrophenol in 600 ml of water, then add 1.191 g of palladium on carbon (5%, 50% water content), and close the reactor. Purge with hydrogen six times, then maintain the pressure at 0.8-0.9 MPa and heat to 80 °C for 8 h. After the reaction is complete, filter the reaction solution, add 2.0 g of thiourea dioxide to the filtrate, and stir for 10 min. Place the filtrate in an ice-water bath, adjust the pH to 3 with 4 mol / L hydrochloric acid, continue stirring for 2 h, filter, and dry at 60 °C to obtain 76.2 g of o-aminophenol, with a yield of 94% and a purity of 98.9%.

[0024] Example 2: Preparation of o-aminophenol.

[0025] Dissolve 120.0 g of sodium o-nitrophenol in 600 ml of water, then add 0.710 g of palladium on carbon (5%, 50% water content), and close the reactor. Purge with hydrogen six times, then maintain the pressure at 0.8-0.9 MPa and heat to 100 °C for 5 h. After the reaction is complete, filter the reaction solution, add 2.0 g of thiourea dioxide to the filtrate, and stir for 10 min. Place the filtrate in an ice-water bath, adjust the pH to 3 with 4 mol / L hydrochloric acid, continue stirring for 2 h, filter, and dry at 60 °C to obtain 77.1 g of o-aminophenol, with a total yield of 95% and a purity of 96.6%.

[0026] Example 3: Preparation of o-aminophenol.

[0027] Dissolve 30.0 g of sodium o-nitrophenol in 200 ml of water, then add 0.30 g of palladium on carbon (5%, 50% water content), and close the reactor. Purge with hydrogen six times, then maintain the pressure at 0.9-1.0 MPa and heat to 85 °C for 8 h. After the reaction is complete, filter the reaction solution, add 0.6 g of thiourea dioxide to the filtrate, and stir for 10 min. Place the filtrate in an ice-water bath, adjust the pH to 3 with 4 mol / L hydrochloric acid, continue stirring for 2 h, filter, and dry at 60 °C to obtain 18.7 g of o-aminophenol, with a total yield of 92% and a purity of 95.3%.

[0028] Example 4: Preparation of o-aminophenol.

[0029] Dissolve 60.0 g of sodium o-nitrophenol in 400 ml of water, then add 0.3 g of palladium on carbon (5%, 50% water content), and close the reactor. Purge with hydrogen six times, then maintain the pressure at 0.7-0.8 MPa and heat to 70 °C for 8 h. After the reaction is complete, filter the reaction solution, add 1.0 g of thiourea dioxide to the filtrate, and stir for 10 min. Place the filtrate in an ice-water bath, adjust the pH to 3 with 4 mol / L hydrochloric acid, continue stirring for 4 h, filter, and dry at 60 °C to obtain 36.9 g of o-aminophenol, with a total yield of 91% and a purity of 95.8%.

[0030] Example 5: Catalyst recycling experiment.

[0031] The catalyst filter cake obtained from filtering the reaction solution in Example 1 was washed three times with water. The experiment was repeated five times under the reaction conditions of Example 1. Although the yield of o-aminophenol decreased slightly, the conversion rate remained above 90% after five cycles (Table 1), indicating that the catalyst has good cycle stability and activity.

[0032] Table 1: Effect of catalyst reuse on the yield and purity of o-aminophenol.

[0033]

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A simple and high-yield method for synthesizing o-aminophenol, characterized in that, Its synthetic route is as follows: ； The specific synthesis steps are as follows: S1. Using sodium o-nitrophenolate as raw material, a certain amount of water is added, H2 is used as a reducing agent, Pd / C is used as a catalyst, and the temperature is raised to react; S2. Filter the reaction solution obtained in S1, add a certain amount of thiourea dioxide to the filtrate, adjust the pH to 3 with hydrochloric acid, stir for a period of time, filter, and obtain the target product o-aminophenol.

2. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S1, the H2 pressure is 0.6~1.0MPa, the reaction temperature is 70~100℃, and the reaction time is 5~10h.

3. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S1, the Pd / C has a palladium content of 5% and a water content of 50%.

4. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S1, the mass ratio of sodium o-nitrophenolate to Pd / C is 1:(0.002~0.01).

5. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S2, the mass ratio of sodium o-nitrophenolate and thiourea dioxide is 1:(0.008~0.02).

6. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S2, the concentration of the hydrochloric acid is 2-4 mol / L.

7. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S2, the acidification process of adjusting the pH with hydrochloric acid needs to be carried out at 10~-10℃.

8. The method for synthesizing o-aminophenol with simple operation and high yield according to claim 1, characterized in that, In step S2, the pH adjustment and acidification process with hydrochloric acid requires stirring for 2-4 hours.

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