[Determination of acid-base amphoteric dissociation constant of 2-methyl-5 (4)-nitroimidazole by UV-spectrophotometry].

The 2-methyl-5(4)-nitromidazole(BH) is an ampholyte with acid and base. It is an intermediate of metronidazole. The amphoteric dissociation constant of BH determined by equimolar UV-spectrophotometry. The acidic dissociation constant pKa is 9.64 +/- 0.04 and the basic dissociation constant pKb is 12.98 +/- 0.02.