Synthesis of 5-nitro- and 5-aminobenzimidazolone-2

The pure mononitro derivative of benzimidazolone-2 can be obtained only when the nitration reaction is carried out in mild conditions, otherwise di-, tri- and tetranitro derivatives are also formed. The results of our studies derived optimum conditions for the nitration process necessary to obtain pure 5-nitrobenzimidazolone-2.