| Popis: |
Spectrophotometric and voltammetric methods of the content determination of the new reagent – sodium 4-[2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)hydrazino]benzoate, which is a representative of azolidones, in an aqueous medium have been developed. The form of absorption spectra of this derivative azolidone is practically independent of the acidity of the media. The effective molar absorptivity coefficients of e 248 = (1.57±0,06)·10 4 and e 390 = (2.50±0.08)·10 4 L×mol -1 ×cm -1 at the absorption maxima were calculated. The sodium 4-[2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)hydrazino]benzoate does not polymerize and does not form tautomeric forms in the concentration range 1.0·10 -5 –1.0·10 -4 M. The linear range for the determination of the reagent using the spectrophotometric method lies within 1.5·10 -6 – 4.0·10 -5 М, and using the voltammetric method – 1.0·10 -6 – 5.0·10 -5 М. The results indicated that the electrochemical reduction of the reagent takes place at one step in wide range of the acidity of the media. The reduction of sodium 4-[2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)hydrazino]benzoate is an irreversible process, which is confirmed by the absence of anodic peaks on the voltammograms. The potential of the reduction peak is linearly shifted to the cathodic area when decreasing the acidity of the media, which indicates the participation of hydrogen ions in the electrochemical process. The dependence of the voltammetric current on the pH of the solution is complicated. It was established that the voltammetric current has the absorptive origin. The probable mechanism of reduction of the new azolidone derivative – sodium4-[2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4 ylidene)hydrazino]benzoate has been proposed. Keywords : voltammetry, spectrophotometry, azolidones, sodium 4-[2-(3-methyl-5-oxo-1-phenyl-1,5-dihydro-4H-pyrazol-4-ylidene)hydrazino]benzoate. |
