Polarographic study of a benzodiazepinooxazole: Oxazolam

Summary The polarographic behaviour of 10-chloro-2,3, 7,11b-tetrahydro-2-methyl-11b-phenyloxazolo-[3,2-d][1,4]-benzodiazepin-6(5H)-one (Oxazolam) was studied in the pH range 1–12. The reduction processes of Oxazolam and its hydrolysis product are irreversible and their currents are predominantly diffusion-controlled. The linear relationship between current and Oxazolam concentration in sulphuric acid medium permits its polarographic determination up to 6.08×10^–5 mol/l. The detection limit was 1.52×10^–7 mol/l (50 ppb). The reproducibility of the method in terms of relative standard deviation was 1.74% and 1.85% for ten determinations at 1.48×10^–5 mol/l and 1.37×10^–6 mol/l levels, respectively. The method developed was applied to the determination of the compound in its formulations, Hializan-10 mg, obtaining errors lower than 2%.

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Polarographische Untersuchung eines Benzodiazepinoxazols: Oxazolam

     

Polarographic study of a benzodiazepinooxazole: Cloxazolam

Summary The polarographic behaviour of 10-chloro-11b-(2-chlorophenyl)-2,3,7,11b-tetrahydrooxazolo[3,2-d][1,4]-benzodiazipine-6(5H)-one (cloxazolam) was studied in the pH range 1–12. Cloxazolam suffers a hydrolysis process, which can be followed by polarography. The reduction processes of cloxazolam and its hydrolysis product are irreversible and their currents are diffusion-controlled. Two polarographic methods have been developed upon the basis of the reduction of both the protonated iminium form (pH 1.45, measurement time: 10 min) and the benzophenone produced in the hydrolysis process (pH 11.75, measurement time: 15 min). The relationship between reduction peak current and concentration is linear up to at least 5.72×10^–5 mol/l for both methods. A higher sensitivity was obtained for the method based on the benzophenone reduction (detection limit 5.72×10^–8 mol/l; 20 ppb). The methods developed were applied to the determination of cloxazolam in its pharmaceutical formulations (Betavel, 1 mg). The method in alkaline medium was the most adequate for the determination of the compound in tablets, with errors lower than 1%.

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Polarographische Untersuchung eines Benzodiazepinoxazols: Cloxazolam

     

Polarographic study of xylenol orange

In neutral medium the ring carbonyl group of xylenol orange is reduced in two one-electronsteps at a dropping mercury electrode. Step I is nearly reversible, but step II strongly irreversible. The half-wave potentials of both steps depend on pH, for the products of reduction, the dye radical formed in step I and the OH group produced in step II, behave as acids. From the E_1/2 vs. pH dependence, the pK of the dye radical is found to be 9.5, that of the hydroxy compound 5.6. On progressive acidification the height of step II continuously decreases, while that of step I increases. In solutions with pH<2, only a single (according to logarithmic analysis) one-electron, but overall (according to coulometry) two-electron step results. The ratio i^I/i^II for the two steps increases when larger amounts of alkali metal ions are added. The exaltation of the first wave at the expense of wave II is explained by an acid-dependent dismutation of the dye radical formed during the first one-electron step.     

Polarographic study of uracil derivatives

Eighteen uracil derivatives were studied by d.c. polarography, differential-pulse (d.p.)polarography and d.p. cathodic stripping voltammetry. In a borax buffer at ca. pH 7.6, uracil, thymine and derivatives such as 5-halouracils, 5-trifluoromethyl-,5-aza-,5-acetyl-, 5-formyl- and 5-vinyl-uracil produced well-defined peaks at potentials between 0 V and ca. 160 mV vs. silver/ silver chloride (satd. KCl). The peaks are ascribed to the formation of sparingly soluble mercury salts. For the other derivatives tested (e.g., 5-nitro- and 5-ethynyl-uracil and 6-substituted uracils), the peaks were less well-defined and in some cases the polarographic curves were very complex. 2-Thiouracil produced a single peak at ca. ?400 mV, but only at pH 12.2. The shapes, heights and potentials of the peaks depended on the kind and position of the substituent on the pyrimidine ring. Rectilinear relationships of peak current vs. concentrations were found for most compounds (10^?5-10^?4 M) by d.p. polarography; d.c.polarography was not tested quantitatively. For 5-fluorouracil and 5-vinyluracil, linear calibrations were found for concentrations of 0.5–5 × 10^?7 M by d.p. cathodic stripping voltametry. Interference studies showed that small amounts of chloride and phosphate did not interfere but 5-fluorodeoxyuridine, which did not itself produce a peak, and proteins interfered seriously.     

On the mechanism of hydrolysis of the triazolobenzodiazepine,triazolam. Spectroscopic study

The hydrolysis of 8-chloro-6-(2′-chlorophenyl)-1-methyl-4H[1,2,4]triazolo[4,3-a][1,4]benzodiazepine (Triazolam) at room temperature, involves a reversible mechanism. The intermediate is a protonated species and the final product is the ring-opened compound resulting from the reversible scission of the imine bond. The two compounds were determined simultaneously as a function of pH with pmr and cmr spectrometry. Spectral data of the benzophenone derivative II (ir, cmr, pmr) are reported.     

Preparation of triazolobenzodiazepine derivatives as Vasopressin V1a antagonists

This Letter describes the synthesis of a number of fused tricyclic and bicyclic triazolobenzodiazepines for the Vasopressin V1a antagonist programme.     

Polarographic study of mixed ligand complexes: Cadmium-imidazole-malonate system

The mixed ligand complexes of imidazole (Im) and malonate (Mal) with Cd(II) have been studied polarographically at constant ionic strength, μ = 2.0 (NaNO₃) and pH 8 at 25 ± 0.1°C. The reduction of the complexes at d.m.e. is reversible and diffusion-controlled. Three mixed complexes, [Cd(Im)(Mal)], [Cd(Im)(Mal)₂]²⁻ and [Cd(Im)₂(Mal)] are formed. Their overall stability constants at 25°C are: log β₁₁ = 4.0, log β₁₂ = 4.4 and log β₂₁ = 5.9, respectively.     

Polarographic study of aliphatic nitro compounds

Conclusions Study bas shown that the first stage in the reduction of 1,1-dinitroethane and fluorodinitromethane in strongly acidic solution is a two-electron C-N bond rupture process, the subsequent stages of the reaction being determined by the relative rates of the competing processes of protonation, nitrosation, and Neff reaction.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 567–573, March, 1977.     

Polarographic study of aliphatic nitro compounds

Conclusions In polarograms of solutions of salts of CH₂(NO₂)₂, CH₃CH(NO₂)₂, FCH(NO₂)₂, and CH₃CH₂NO₂ in abs. methanol, an anodic wave is present, due to increased ionization of mercury, by the tying up of mercury ions with the anions of these compounds to form slightly dissociated organomercury compounds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2021–2023, September, 1980.     

Polarographic study of some stable phenoxyl radicals

Conclusions A study was made of the polarographic reduction of phenoxyl radicals.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2844–2845, December, 1971.     

双硫腙水溶液的极谱研究

用单扫描极谱法和循环伏安法研究了双硫腙在酸性和碱性水溶液中的极谱行为.在碱性介质中,有三个还原波-0.63,-0.52和-0.45V,分别对应于双硫腙阴离子,它的氧化产物四氮化合物和二硫化合物的还原过程,在酸性介质中,只有一个-0.18V的双硫腙还原波.上述波的电极反应和特征也讨论了.