To a mixture of 2-nitro-benzene-1,4-diamine (10 g, 65.30 mmol) and N,N-dimethylaniline (8.7 g, 71.83 mmol) in acetonitrile (310 ml) at 0° C. 4-isopropyl-benzenesulfonylchloride (13.85 g, 63.34 mmol) was added over a period of 1 h. The mixture was stirred at 0° C. for 1 h and for 16 h at room temperature. After concentrating the mixture in vacuo the obtained oil was triturated with water. The precipitate was collected, washed with ethanol and dried in vacuo to give the product as a yellow powder (11.76 g, 54%).
