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Method for preparing phthalic acid through phthalylhydrazine in electrochemical oxidation manner

A technology of phthalic hydrazide and phthalic acid, which is applied in the field of preparation of phthalic acid, can solve the problems of casualties, property, large amount of addition, high price, etc., and achieve avoidance of large-scale use, mild reaction conditions, less corrosive effect

Active Publication Date: 2016-04-13
BEIJING UNIV OF TECH
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Problems solved by technology

Both concentrated nitric acid and hydrogen peroxide have strong oxidizing properties. During mass production in factories, due to the large amount of reagents required, these reagents will bring very large safety hazards, causing casualties or property losses
[0005] (2) The price is expensive and the equipment loss is high
The above two reagents are added in a large amount during factory production, and the price of purchasing reagents is very expensive
Concentrated nitric acid or hydrogen peroxide has a strong corrosive effect on production equipment. If the factory adopts these two methods for waste disposal, it may need to replace equipment frequently, which virtually increases production costs.
[0006] (3) Cause environmental pollution, especially concentrated nitric acid oxidation method, in the reaction process, can produce poisonous gas, cause bigger pollution to factory surrounding environment
[0008] At present, the method of decomposing phthalic hydrazide to obtain phthalic acid by the constant current electrolysis method has not been reported in the literature at home and abroad.

Method used

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  • Method for preparing phthalic acid through phthalylhydrazine in electrochemical oxidation manner

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Embodiment 1: Phthalic acid is obtained by electrochemical oxidation of phthalic hydrazide

[0024] In the single-chamber electrolytic cell, add 50ml of water, add 6.2mg of sodium hydroxide, and adjust the pH value of the water to 10-11. Weigh phthalic hydrazide (1.0mmol) and then add sodium bromide (2mmol), use graphite sheet as anode, iron sheet as cathode, current density 5mA / cm 2 Electrolyze under constant current, and the reaction temperature is room temperature (30°C). After 5 hours and 50 minutes, the energization was completed, and the pH value of the system was adjusted to about 1 by adding hydrochloric acid, and then filtered with a Buchner funnel. Finally, heat and suspend to dry off most of the water, the heating temperature is about 80°C, and put it into the refrigerator for recrystallization. Yield: 16%.

Embodiment 2

[0025] Example 2: Phthalic acid is obtained by electrochemical oxidation of phthalic hydrazide

[0026] In the single-chamber electrolytic cell, add 50ml of water, add 6.5mg of sodium hydroxide, and adjust the pH value of the water to about 10. Weigh phthalic hydrazide (1mmol) into the system, then add sodium bromide (1mmol), use graphite sheet as anode, stainless steel sheet as cathode, current density 10mA / cm 2 Electrolyze at a constant current, and the reaction temperature is room temperature (30°C). After 4 hours, the electricity is turned on, and the pH value of the system is adjusted to about 1 by adding hydrochloric acid, and then filtered with a Buchner funnel. Finally, heat and suspend to dry off most of the water, the heating temperature is about 80°C, and put it into the refrigerator for recrystallization. Yield: 33%.

Embodiment 3

[0027] Embodiment 3: Phthalic acid is obtained by electrochemical oxidation of phthalic hydrazide

[0028] In the single-chamber electrolytic cell, add 50ml of water and 6.0mg of sodium hydroxide to adjust the pH value of the water to about 10. Weigh phthalic hydrazide (1mmol) into the system, then add sodium bromide (0.5mmol), use graphite sheet as anode, stainless steel sheet as cathode, current density 10mA / cm 2 Electrolyze at a constant current, and the reaction temperature is room temperature (30°C). After 4 hours of electrification, add hydrochloric acid to adjust the pH of the system to about 1, and then filter with a Buchner funnel. Finally, heat and suspend to dry off most of the water, the heating temperature is about 80°C, and put it into the refrigerator for recrystallization. Yield: 35.5%.

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Abstract

The invention provides a method for preparing phthalic acid through phthalylhydrazine in an electrochemical oxidation manner and belongs to the technical field of phthalic acid preparation. The method includes the steps that in a single-chamber electrolytic tank, the phthalylhydrazine is added to a sodium hydroxide solution, alkali halide is added as a catalyst, and the phthalic acid is prepared through the constant current at the indoor temperature. By the adoption of the method, the phthalylhydrazine is electrochemically catalyzed and oxidized to synthesize the phthalic acid for the first time, and potential hazardous hydrogen peroxide or concentrated nitric acid is prevented from being used, and equipment corrosion and environmental pollution which are caused due to the utilization of the hydrogen peroxide or concentrated nitric acid is avoided as well. No extra supporting electrolyte is needed, a common industrial reagent and conventional production conditions are used, the reaction conditions are gentle, the cost is greatly reduced, post-treatment is simple, and the method is more suitable for industrial production.

Description

technical field [0001] The invention relates to a method for preparing phthalic acid from phthalic hydrazide through electrochemical oxidation, and belongs to the technical field of phthalic acid preparation. Background technique [0002] Phthalohydrazide (PHAH 2 ) is a by-product in the synthesis of some drugs. The government expressly prohibits enterprises from discharging substances containing high concentrations of phthalohydrazide into the surrounding environment at will, causing them to contact groundwater, waterways or sewage systems. Therefore, at present, most enterprises acidify or incinerate it, which cannot be transformed and utilized well. The utilization rate of production raw materials is reduced, thereby reducing the economic benefits of the enterprise. It may even be punished by the government for failing to meet the emission standards. [0003] Regarding how to convert phthalic hydrazide into phthalic acid, there are currently two methods. Concentrated ...

Claims

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Application Information

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IPC IPC(8): C25B3/02C25B3/23
CPCC25B3/23
Inventor 曾程初李嘉树田玉福胡利明
Owner BEIJING UNIV OF TECH
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