Global analysis of kinetic current in DC polarography

Blázquez, Manuel; Jiménez, M.; Camacho, Luis; Domí­nguez, Manuel

doi:10.1016/0022-0728(88)80036-6

Cited by 10 publications

(5 citation statements)

References 12 publications

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“…The pH value of the solution affects the distribution of the equilibrium concentrations between unprotonated and protonated species. According to Camacho et al, , both the protonated and the unprotonated ALPY molecules are electroactive and they will be reduced at the same potential at the same pH. Although no data for the dissociation constant of the ALPY radical have been found in the literature, there is no doubt that higher pH value favors the unprotonated form of the radical.…”

Section: Resultsmentioning

confidence: 99%

“…The dimerization of the radical produced by one-electron transfer should also be possible. ,,, In both acidic and basic media, the dimerization competes with the further reductions. Which one predominants depends on their reaction rates under the given conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Under all pH conditions, no CO stretching band at about 1700 cm -1 31,32 is detected. One reason for the absence of the CO stretching band is that in aqueous solution, whether acidic or basic, ALPY exists predominantly in the hydrolyzed form, Py−CH(OH) 2 , rather than aldehyde form. , Another reason for loss of this band would be a surface quenching effect by strong interaction with the surface. The different ALPY spectra in acidic and in basic media are probably related to both protonation and orientations of ALPY on the Ag surface.…”

Section: Resultsmentioning

confidence: 99%

“…The course of the electroreduction of aromatic aldehydes has been studied intensively by polarography. − In many of the above referenced studies the products of the electroreduction were analyzed ex situ by UV−vis and IR spectroscopy or by chromatography after long-time electrolysis. Thus, no information about the identity of intermediates was obtained.…”

Section: Introductionmentioning

confidence: 99%

“…The protonated forms of the species are related to these unprotonated species by the following reactions: ,− Both H + Py−CHO and Py−CHO are electroactive.…”

Section: Introductionmentioning

confidence: 99%

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A Time-Resolved SERS Study of the Adsorption and Electrochemical Reduction of 4-Pyridinecarboxaldehyde and 4-(Hydroxymethyl)pyridine

et al. 1998

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The electroreduction processes of both 4-pyridinecarboxaldehyde, 4-ALPY, and 4-(hydroxymethyl)pyridine, 4-HMPY, have been studied in aqueous solution on a Ag electrode using surface-enhanced Raman spectroscopy, SERS, and cyclic voltammetry, CV. Each electrode process was investigated at pH 3 and at pH 7 in 0.1M KCl electrolyte. SERS spectra show that both the neutral 4-ALPY and a species which is protonated on the aldehyde group (Py-CHOH + ) adsorb on the roughened Ag electrode surface with an end-on orientation through the pyridine nitrogen, but the species with a protonated ring (H + Py-CHO) prefers adsorption with a face-on orientation through its π-system. The electrochemical reduction of ALPY produces a common product, 1,2-bis(4-pyridyl)ethane (BPE), in both acidic and basic media. The major reaction process was studied by time-resolved SERS, TR-SERS, in the time range of 0.1 to 30 ms. A transient intermediate appears at 3.0 ms and is suggested to be the pinicol Py-CH(OH)CH(OH)-Py on the basis of a Gaussian 94 ab initio frequency calculation. It disappears by 10 ms, at which time the BPE product spectrum is established. The reduction of HMPY also undergoes similar reaction pathways in both acidic and neutral pH conditions, and the major product is the same in either condition. A striking fact is that the reduction of HMPY on Ag produces the same product as that of the ALPY, i.e., 1,2-bis(4-pyridyl)ethane (BPE). The surface species for the reactants and the product on the Ag electrode have been identified by SERS, and vibrational assignments of these species have been made.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…The protonated forms of the species are related to these unprotonated species by the following reactions: ,− Both H + Py−CHO and Py−CHO are electroactive.…”

Section: Introductionmentioning

confidence: 99%

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