Synthesis
General procedure for the synthesis of 3,5-difluoro-1,2-phenylenediamine from 2,4-difluoro-6-nitroaniline: concentrated hydrochloric acid (10 mL) was slowly added dropwise to a mixture of 2,4-difluoro-6-nitroaniline (1.6 g, 9 mmol) and tin powder (22.5 mmol). The reaction mixture was heated to reflux for 1.5 h, subsequently cooled to room temperature and neutralized with 50% NaOH solution to pH 9-10. The precipitate was collected by filtration, dried and extracted with hot ethyl acetate (80 mL). The filtrate was subjected to secondary evaporation to give 3,5-difluoro-1,2-benzenediamine. Yield: 0.60 g (46%); the product was brown crystals; melting point 55-57 °C; Rf value was 0.86.
References
[1] Tetrahedron Letters, 2006, vol. 47, # 27, p. 4591 - 4595
[2] European Journal of Medicinal Chemistry, 2009, vol. 44, # 7, p. 2930 - 2935
[3] Synthesis (Germany), 2016, vol. 48, # 3, p. 394 - 406
[4] Journal of the American Chemical Society, 1951, vol. 73, p. 153
[5] Journal of the American Chemical Society, 1959, vol. 81, p. 94,98
