3-Nitro-o-phenylenediamine can be used as a pharmaceutical synthesis intermediate. It can be prepared by using 2,6-dinitrochlorobenzene as a reactant to prepare intermediate 2,6-dinitroaniline, which is then further reacted with sodium sulfide to obtain the final product.
3-Nitro-o-phenylenediamine can be used to synthesize 4-nitro-2-benzimidazole: 1319.6 kg of 99.4% pure 3-nitro-o-phenylenediamine is mixed with 565.4 kg of urea and 1847.4 kg of 69% sulfuric acid, stirred, and heated to 108-110℃ until the reaction is complete, yielding 1521.9 kg of 98.8% pure 4-nitro-2-benzimidazole, with a yield of 98.0%.
General procedure for the synthesis of 3-nitro-o-phenylenediamine from 2,6-dinitroaniline: 14 g of 1-amino-2,5-dinitrobenzene was dissolved in 225 mL of methanol, followed by the slow addition of a solution prepared from 60 g of sodium sulfide and 21 g of sodium bicarbonate dissolved in 240 mL of water. The rate of addition was controlled through a dropping funnel while maintaining the temperature of the reaction system at 60 °C. After the addition was completed, the reaction continued to be stirred at 60°C for 1 hour. Upon completion of the reaction, the reaction mixture was cooled to room temperature and subsequently separated by filtration. The product was analyzed by mass spectrometry showing a m/z (FD+) of 153 (calculated value 153.1396). 1H-NMR spectrum showed chemical shifts of 7.7228, 7.7203, 7.7026, 7.2433, 6.9245, 6.6209, 6.6063, 6.6038, 6.5886, 5.9210, 3.3978 ppm. A final reddish brown fine crystal product of 7.79 g was obtained with a yield of 66.5% and a melting point of 140 °C.
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