Synthesis
General procedure for the synthesis of 1,3-dichloro-2-methyl-5-nitrobenzene from 4-nitrotoluene: A mixture of 4-nitrotoluene (2.415 g, 30.3 mmol), trichloroisocyanuric acid (7.00 g, 30.1 mmol), and concentrated sulfuric acid (25 mL) was stirred for 20 hr at 60° C. The reaction was carried out in a cooled room and then poured into ice water (100 mL). Upon completion of the reaction, the mixture was cooled to 25°C and subsequently slowly poured into ice water (100 mL). The resulting mixture was filtered through a diatomaceous earth pad (20 g) and the diatomaceous earth pad was washed with ether (50 mL). The organic layer of the filtrate was separated and the aqueous layer was extracted with ether (2 x 20 mL). The organic layers were combined, washed with brine (2 x 30 mL), dried over anhydrous sodium sulfate (20 g), and subsequently concentrated under reduced pressure to give the crude product (6.68 g) as a light yellow solid. A mixture of the crude product (6.68 g), copper powder (6.05 g, 95.2 mmol) and chlorobenzene (7 mL) was stirred at 25°C for 5 min, then acetic acid (4.9 mL) was added and the reaction mixture was refluxed for 20 hours. After completion of the reaction, it was cooled to 25°C, filtered through a diatomaceous earth pad, and the diatomaceous earth pad was washed with toluene (30 mL). The filtrate was washed with brine (3 x 15 mL), dried over anhydrous sodium sulfate (5 g) and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (100 g) using hexane as eluent to afford the target product 1,3-dichloro-2-methyl-5-nitrobenzene (4.47 g, 73% yield) as a light yellow solid.
References
[1] Tetrahedron, 2016, vol. 72, # 5, p. 720 - 725
[2] Gazzetta Chimica Italiana, 1996, vol. 126, # 3, p. 179 - 185
[3] Journal of the Chemical Society, 1926, p. 1416
[4] Journal of the Chemical Society, 1931, p. 79,81
[5] Tetrahedron, 1998, vol. 54, # 12, p. 2953 - 2966
