Synthesis
The general procedure for the synthesis of 3,4-dicyanophenol from 4-nitrophthalonitrile was as follows: 1) 103.9 g (600 mmol) of 4-nitrophthalonitrile and 800 mL of dimethyl sulfoxide (DMSO) were added to a three-necked flask equipped with a stirrer. After the solid was completely dissolved, 91.0 g (660 mmol) of potassium carbonate and 46.0 g (660 mmol) of sodium nitrite were added sequentially. The reaction mixture was heated to 160 °C and kept at reflux for 5 hours. Upon completion of the reaction, the mixture was cooled to room temperature and subsequently poured into a large amount of water to precipitate the product. The yellow solid was collected by filtration and dried under vacuum at 110 °C to give 73.3 g of 4-hydroxyphthalonitrile in 85% yield.
References
[1] RSC Advances, 2015, vol. 5, # 96, p. 79207 - 79215
[2] Patent: CN104910113, 2017, B. Location in patent: Paragraph 0041-0042; 0045-0046
[3] Synthetic Communications, 1989, vol. 19, # 18, p. 3231 - 3240
[4] Russian Journal of General Chemistry, 2011, vol. 81, # 4, p. 768 - 772
