Polarography of some arylazothiohydantoin derivatives

Darwish, S.; Fahmy, H. M.; Aziz, M. A. Abdel; El‐Maghraby, A. A.

doi:10.1039/p29810000344

Cited by 19 publications

(11 citation statements)

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“…[35][36][37][38] Physicochemical properties TH proton-exchange thermodynamic constants: We first examined the acid-base properties of the trans stereoisomers TH of the present 2-hydroxyazobenzenes. To avoid any problem of solubility in the whole series, water/acetonitrile 1:1 (v/v) was used as a solvent.…”

Section: Resultsmentioning

confidence: 99%

2‐Hydroxyazobenzenes to Tailor pH Pulses and Oscillations with Light

Emond

Saux

Maurin

et al. 2010

Chemistry A European J

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This paper evaluates the 2-hydroxyazobenzene platform for tailoring proton concentration pulses and oscillations with monochromatic light. The easily prepared 2-hydroxyazobenzenes exhibit large absorptions in the near-UV range. Photoisomerization was investigated by UV/Vis absorption, (1)H NMR spectroscopy, and steady-state fluorescence emission. In the whole investigated series, the trans stereoisomer of the 2-hydroxyazobenzene motif provides the corresponding cis derivative with an action cross section in the 10(3) M(-1) cm(-1) range. At the same time, photoisomerization is accompanied by a significant pK drop of the phenol group. According to the phenyl-substituent pattern, cis-to-trans thermal back-isomerization can be tuned in the 10 ms-100 s range. Up to 2 units of reversible pH drops or pH oscillations on the 10 s timescale have been obtained by appropriately tailoring single-wavelength illumination of 2-hydroxyazobenzene solutions.

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Section: Resultsmentioning

confidence: 99%

2‐Hydroxyazobenzenes to Tailor pH Pulses and Oscillations with Light

Emond

Saux

Maurin

et al. 2010

Chemistry A European J

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“…Oxazolones (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15) were prepared according to recommended procedure (13). The purity and structures of the compounds were checked by measurements of mp, nmr, mass spectra, and elemental analysis.…”

Section: Methodsmentioning

confidence: 99%

“…Numerous studies have been devoted to the chemistry, electrochemistry, and spectroscopy of heterocyclic compounds, specially those exhibiting applications in biological and medicinal researches (1,2). On the other hand, the polarographic behaviour of the oxazole ring, structurally a heterocyclic system, has attracted only minor attention in literature (3, 4) as compared to major spectroscopic investigations (5)(6)(7)(8)(9)(10).…”

Section: Introductionmentioning

confidence: 99%

“…Consequently, in the present investigation our attention was devoted mainly to oxazolones possessing wide applications in the electrosyntheses of various amino alcohols, thiamine, and amino acids (11,12). The study was focussed on the polarographic behaviour of some oxazolones (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), in Thiel buffer -ethanolic solutions of different pH values as well as in DMF. The electrode reaction mechanism and various physical properties of these compounds were also investigated.…”

Section: Introductionmentioning

confidence: 99%

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Physical characteristics and polarographic reduction mechanism of some oxazolones

Ismaïl¹

1991

Can. J. Chem.

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M. I. ISMAIL. Can. J. Chem. 69, 1886 (1991.The redox potential (AEI12), electron affinity (EA), ionization potential (IP), coulomb repulsion integral (J12). and electronic transition energy (ECT) of several oxazolone derivatives in DMF were computed. A linear correlation was shown to exist between and ECT The polarographic reduction was investigated in ethanolic-Theil buffer solutions. At pH < 7.2, two waves were obtained representing the uptake of 2-and 4-electron steps respectively. In alkaline media, a third wave appeared seemingly a result of the hydrolysis of oxazolones. The rate of hydrolysis was determined and the electrode mechanism was elucidated and confirmed via spectrophotometric and coulometric analysis.

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“…In acid pH solutions nifuroxazide exhibited four reduction peaks. Since the nitro group is more easily reducible than the hydrazono group 7,8 , these peaks can be attributed to the subsequent reduction of nitro group and the reductive fission of hydrazono group.…”

Section: Capsule Analysismentioning

confidence: 99%

Determination of Nifuroxazide in Capsules by Differential Pulse Polarography

1998

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Nifuroxazide, 4-hydroxybenzoic acid [(5-nitro-2-(furanyl)methylene]hydrazide (I) is used for the treatment of acute and chronic diarrhea, gastroenteritis, and colitis. Analytical methods used for the determination of nifuroxazide include titrimetric 1 , complexometric 2 , ultraviolet spectrophotometric 3 , and HPLC. 3 At present, only a few studies dealing with nifuroxazide polarographic behavior have been reported and the authors seems to have encountered only two waves. [4][5][6] In this work, the polarographic behavior of nifuroxazide and its analytical utility have been investigated. Experimental ReagentsStock solutions (1´10 -3 M ) of nifuroxazide were prepared daily in DMSO and stored at 4˚C in the dark. Britton-Robinson buffers were used as supporting electrolytes. All reagents were of AnalaR-reagent grade in doubly distilled water. ApparatusThe differential pulse polarograms have been recorded using a polarographic analyzer (PAR Model 264A) coupled with a PAR 303A static mercury drop electrode. All the potentials are referred to Ag/AgCl/3 M KCl reference electrode and a platinum wire is used as counter electrode.A SCHOTT GerÄte pH-meter with glass combination electrode was used for pH determination. ProcedureThe supporting electrolyte solution (9.5 ml) with an aliquot of nifuroxazide in DNSO, diluted to 10 ml with DMSO, was added to the cell. The cell was degassed by purging with purified nitrogen for 8 min. The voltammetric curves were recorded in the cathodic direction. Capsule analysisTo eliminate the inconstancy of weight, the contents of 20 Antinal capsules of several packages were carefully weighed and then mixed. An average weight of one capsule was dissolved in ethanol, filtered and washed with ethanol. The residue was evaporated till dryness and dissolved in 10 ml DMSO and 0.5 ml of the solution was then transferred to the polarographic cell containing 0.5 ml DMSO and 9 ml BritonRobinson buffer (pH 4.0). The concentration was calculated using a calibration graph or regression equation. Keywords Nifuroxazide, differential pulse polarography † To whom correspondence should be addressed.

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Polarography of some arylazothiohydantoin derivatives

Cited by 19 publications

References 0 publications

2‐Hydroxyazobenzenes to Tailor pH Pulses and Oscillations with Light

2‐Hydroxyazobenzenes to Tailor pH Pulses and Oscillations with Light

Physical characteristics and polarographic reduction mechanism of some oxazolones

Determination of Nifuroxazide in Capsules by Differential Pulse Polarography

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