Synthesis
General procedure for the synthesis of 2,5-dimethyl-4-nitrophenol from 2,5-dimethylphenol:
1. 61.00 g (0.50 mol) of 2,5-dimethylphenol was weighed and placed in a 500 mL three-necked flask, 200 mL of glacial acetic acid was added and stirred until completely dissolved.
2. 40 mL of water was mixed with an appropriate amount of sulfuric acid and slowly added dropwise to the reaction flask and stirred at room temperature for 30 minutes.
3. Transfer the reaction flask to a low temperature bath at 5 to 10°C. Slowly dropwise add 35.00 g (0.50 mol) of sodium nitrite dissolved in 40 mL of water, and continue stirring for 15 minutes after completion of the dropwise addition.
4. The reaction solution was poured into 1 L of water, a yellow solid was precipitated, filtered and air-dried.
5. Place the nitrosyl product obtained in the previous step in a 500mL three-necked flask, add 150mL of water, slowly add 70mL of 68% nitric acid, control the reaction temperature at 40~50°C, react for 1 hour after dropwise addition is completed, and then continue the reaction for 10~15 minutes.
6. Pour the reaction solution into 1L of water, precipitate, filter and dry.
7. The crude product was recrystallized with a mixed solvent of toluene-petroleum ether to obtain 76.82 g of dark yellow solid product in 92.0% yield.
References
[1] RSC Advances, 2013, vol. 3, # 40, p. 18609 - 18613
[2] Journal of the American Chemical Society, 1919, vol. 41, p. 2041
[3] Journal of the American Chemical Society, 1954, vol. 76, p. 4979,4981
[4] Liebigs Annalen der Chemie, 1985, vol. 1985, # 7, p. 1398 - 1412
[5] Gazzetta Chimica Italiana, 1882, vol. 12, p. 162
