Overview of the production method of 1,4-Phthalaldehyde

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Overview of the production method of 1,4-Phthalaldehyde

As an important organic synthesis and fine chemical raw material, 1,4-Phthalaldehyde has many production methods. The application of phthalaldehyde is also widely used, such as dyes, fluorescent whitening agents, medicines, spices and the like.

The main production method for 1,4-Phthalaldehyde will be introduced in this article.

To a 250 mL three-necked flask equipped with a reflux condenser and a stirring device, 6.0 g of sodium sulfide, 2.7 g of sulfur powder, 5 g of sodium hydroxide and 60 mL of water were added, and the mixture was heated to 80 ° C with stirring, and the yellow sulfur powder was dissolved. The solution turned red and was kept under reflux for 1 h to give a dark red sodium polysulfide solution.

Add 13.7 g of p-nitrotoluene, 80 mL of industrial ethanol, 0.279 g of N, N-dimethylformamide, 2.0 g of urea to a 250 mL three-necked flask equipped with a dropping funnel, a reflux condenser, and a stirring device. Stirring was carried out to dissolve p-nitrotoluene to give a pale yellow solution. The temperature gradually rises to 80 ° C, the temperature is constant, and the sodium polysulfide solution prepared by the step is added dropwise. The solution quickly turns blue, and then turns into dark green to dark brown, and finally reddish brown, which drops within 1.5 to 2.0 h. After completion, the temperature was kept at 80 ° C for 2 h. Steam distillation was carried out rapidly, while 100 mL of water was added dropwise, and about 150 mL of distillate was collected. The pH was checked to be 7. The residue was quickly cooled with ice, and pale yellow crystals were separated and extracted with diethyl ether (30 mL×5). Ether was evaporated and dried to give the title compound as a yellow solid.

In a 250 mL three-necked flask, add 5.89 paraformaldehyde, 13.2 g of hydroxylamine hydrochloride, and 85 mL of water, stir with stirring, and dissolve all the solution to obtain a colorless solution. Then add 25.5 g of sodium acetate hydrate, keep warm at 80 ° C, and reflux for 15 min. That is, formaldehyde hydrazine (10%) is a colorless solution.

Add 3.5 g of p-aminobenzaldehyde, 10 mL of water, and add 5 mL of concentrated hydrochloric acid to a 50 mL beaker, and stir constantly. The pale yellow material quickly turns black, dissolves continuously, and can be heated appropriately (below 6 ° C). It is completely dissolved, cooled under ice salt bath, and the temperature drops below 5 °C. At this time, the hydrochloride of p-aminobenzaldehyde is precipitated as fine particles, and the solution is paste-like. After stirring, 5 mL is dripped within 5-10 min. The sodium nitrite solution was stirred for about 20 minutes, and adjusted to a Congo red test paper with a 40% sodium acetate solution to obtain a diazonium salt solution.

0.7 g of crystalline copper sulfate, 0.2 g of sodium sulfite, and 1.6 g of sodium acetate hydrate were dissolved, and added to a 10% formaldehyde hydrazine solution, and the solution became grass green. Under ice cooling, the diazonium salt solution was added dropwise, and a large amount of air bubbles appeared immediately. After the completion of the dropping, the reaction was kept at a low temperature for 30 min to obtain a gray solution. 30 mL of concentrated hydrochloric acid was added, and the mixture was heated to 100 ° C for 1 h, and the solution was orange. Steam distillation, a white solid with a slight yellow color, suction filtration, drying to obtain crude terephthalaldehyde. Recrystallization from a 1:1 mixture of alcohol and water gives terephthalaldehyde.

The above is the introduction of the main production methods of 1,4-Phthalaldehyde, if you have any ideas, please contact us!

August 14th, 2019|0 Comments

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