A spectrophotometric and polarographic investigation of three new cyclohexene-substituted benzodiazepines

• Published in: Talanta (Oxford) 1978-04, Vol.25 (4), p.209-213
• Main Authors: Volke, J., Ellaithy, M.M., Manoušek, O.
• Format: Article
• Language: English
• ISSN: 0039-9140; 1873-3573
• DOI: 10.1016/0039-9140(78)80006-X

Three recently introduced benzodiazepine derivatives, tetrazepam ( I), nortetrazepam ( II) and menitrazepam ( III) have been subjected to spectral and polarographic investigation. From the ultraviolet spectral data their p K a-values have been determined: 4.28 ( I), 4.3 ( II) and 3.5 ( III). From the polarographic measurements it can be concluded that in I and II the 4,5 CN double bond is reduced with 2 electrons. For the first time for the benzodiazepine series it has been observed that in slightly alkaline solutions this process takes place in two separate 1-electron steps. In III, first the aromatic nitro group is reduced to a hydroxylamine group, then at more negative potentials the CN double bond is also reduced; its reduction wave mostly coalesces with that for the 6-electron reduction of the nitro group to an amino group. A differential pulse polarographic method is presented, for the determination of I, II, III at concentrations as low as 10 −7 M.