Polarographic study of xylenol orange

Véber, M.; Csányi, László J.

doi:10.1016/s0022-0728(79)80054-6

Cited by 13 publications

(4 citation statements)

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“…The ratio of the oxidation peak current to the reduction peak current is smaller than one, but it approaches one when the scan rate is increased. The features of the first redox couple at both the gold minigrid and glassy carbon electrodes are similar to those reported for a mercury electrode [7], which shows that XO undergoes a quasi-reversible reduction process at the first step (with a following chemical reaction) and that the second reduction process is totally irreversible. both the intermediate and final reduction products have no absorbance in the UV-visible region, which suggests that the conjugated system is partly destroyed during the electroreduction step (i.e., the electroreduction of XO occurs at one carbonyl group of one of the benzyl rings with conjugated structure).…”

Section: Results and Discusion Cyclic Voltammetry Of Xylenol Orangesupporting

confidence: 74%

“…The 275-nm absorption band is shifted slightly to a longer wavelength range. In addition, a very small and sharp absorption band was found at 355 nm, which is slightly different from the spectrum of the final reduction product of XO, the latter having no such spectrum [7]. This newly discovered spectrum peak is probably induced by the unpaired electron of the XO radical produced at the first reduction step.…”

Section: Reagentsmentioning

confidence: 78%

“…This newly discovered spectrum peak is probably induced by the unpaired electron of the XO radical produced at the first reduction step. After a long period of electrolysis at -0.5 V, this small absorption band disappears (curve f' in Figure 3), producing the spectrum of the final reduction product [7], which is similar to the spectrum of the final reduced Chromazurol S [ …”

Section: Reagentsmentioning

confidence: 94%

“…All of the solutions were prepared with twice-distilled water. The test solutions were purged with pure W-Visible Spectv-oelectmchemistry of Xyleno I Orange Depending on the dissociation of the protons in the structure, the spectrum of XO varies with the pH of the solution [7,101. The color of the XO solution is yellow at pH < 6.…”

Section: Reagentsmentioning

confidence: 99%

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UV‐visible and ESR spectroelectrochemical study of xylenol orange

Dong

Song

1989

Electroanalysis

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The proposed first step in the electroreduction of xylenol orange (XO), a reversible electrode process coupled with a chemical reaction, is based on ultraviolet (UV)-visible spectroelectrochemistry. Electrochemical excitation-electron spin resonance (ESR) in situ measurements are used to observe the radical signal produced by the first step reduction of XO. The ESR spectra of the radical in solution at pH 4.0, 4.5, and 5.0 have the same characteristics: no observed hyperfine structure, a line width of 10.5 G, and a g value of 2.0034. The structure of the XO radical and its disproportionation reaction are elucidated. l7tTRODUCTIONMany organic dyes are widely used in electroanalytical chemistry [ 11. Some electroinactive metals can be determined indirectly by forming complexes with electroactive organic dyes c l so;The electrode process of XO at a mercury electrode was investigated by Veber and Csanyi 171. It was proposed that XO undergoes two electron-transfer steps, with step 1 being nearly reversible and followed by a chemical reduction and step 2 being strongly irreversible. The first I To whom correspondence should be addressed step is, in fact, more important for most electroanalytical applications. No additional information is available on the first electroreduction step (especially on the structure of the XO radical and the nature of the following chemical reaction). Spectroelectrochemical investigations dealing with basic triphenylmethane dyes have rarely been reported. This article explores the electrode process of XO by using in situ ultraviolet (W)-visible and electron spin resonance (ESR) spectroelectrochemical methods as well as cyclic voltammetry. EXPERIMENTAL InstrumentationAn electron spin resonance spectrometer (Japan, JES-FE-3AX, x band, 100 kHz modulation, TJhI microwave resonance cavity) was combined with an FA-1 model voltammeter made by our laboratory for carrying out the in situ ESK spectroelectrochemical measurements. The IN-visible spectroelectrochemical equipment consisted o f a DMS-90 UV-visible spectropliotometer (Varian Instrument Co., Palo Alto, a) and a 1'MC nlodel 173 potentiostat. Both the ESK-electrocheniicaI cell and the gold minigrid optically transparent thin-layer cell were described previously [ 8, 91. All potentials were measured against an Ag/AgCI (saturated KCI solution) reference electrode. The experiments were performed ;it 20°C. ReagentsAnalytical grade xylenol orange was used without further purification. Other chemicals were also of analytical grade. All of the solutions were prepared with twice-distilled water. The test solutions were purged with pure 0 1989 VCH Publishers, Inc

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Section: Results and Discusion Cyclic Voltammetry Of Xylenol Orangesupporting

confidence: 74%

Section: Reagentsmentioning

confidence: 78%

Section: Reagentsmentioning

confidence: 94%

Section: Reagentsmentioning

confidence: 99%

See 2 more Smart Citations