“…A voltammogram recorded in a 5:1 (v/v) mixture of water and ethanol with 0.1 M sodium perchlorate as supporting electrolyte and saturated with tetra( n -hexyl)ammonium perchlorate exhibits a single, sharp surface peak at about −1470 mV. Previous work has shown that tetra(alkyl)ammonium ions specifically adsorb on a mercury electrode in a restricted potential range. − At potentials at either end of this range, the desorption process results in the formation of sharp capacitance peaks in the voltammograms. In this respect, the adsorption behavior of tetra(alkyl)ammonium ions resembles that of an organic species rather than an inorganic ion.…”
Section: Resultsmentioning
confidence: 99%
“…The inset shows the voltammetric curves recorded for the first one-electron reduction of C 60 at different sweep rates (10, 5, 2, 1, and 0.5 V/s). 6 Diffusion coefficients for C 60 in various solvents plotted against the reciprocal of the solvent viscosity. The data were taken from ref (▴) or ref (◆) or calculated from the data obtained in this paper (▪).…”
A novel approach to electrochemistry in thin layers of organic solvents is presented. These layers are formed in situ from benzene, o-dichlorobenzene, or dichloromethane on a hanging mercury drop electrode (HMDE). Very thin organic layers are formed by the expansion of a mercury drop and an organic layer into an aqueous bulk phase. The process of expansion and formation of the thin organic layer on mercury was studied by optical microscopy. Modification of the HMDE by these thin layers of organic solvents significantly limits the reduction of metal ions from the aqueous bulk solution. The redox behavior of C 60 in these thin films is shown to be highly solvent dependent. This dependence is demonstrated by comparison of the cyclic voltammetry of C 60 in a benzene layer with that in an o-dichlorobenzene layer. In the potential range from 0 to -1200 mV, two reversible reduction processes are observed for C 60 . In benzene, with its very low dielectric constant, the electrode processes are complicated by the precipitation of fulleride salts.
“…A voltammogram recorded in a 5:1 (v/v) mixture of water and ethanol with 0.1 M sodium perchlorate as supporting electrolyte and saturated with tetra( n -hexyl)ammonium perchlorate exhibits a single, sharp surface peak at about −1470 mV. Previous work has shown that tetra(alkyl)ammonium ions specifically adsorb on a mercury electrode in a restricted potential range. − At potentials at either end of this range, the desorption process results in the formation of sharp capacitance peaks in the voltammograms. In this respect, the adsorption behavior of tetra(alkyl)ammonium ions resembles that of an organic species rather than an inorganic ion.…”
Section: Resultsmentioning
confidence: 99%
“…The inset shows the voltammetric curves recorded for the first one-electron reduction of C 60 at different sweep rates (10, 5, 2, 1, and 0.5 V/s). 6 Diffusion coefficients for C 60 in various solvents plotted against the reciprocal of the solvent viscosity. The data were taken from ref (▴) or ref (◆) or calculated from the data obtained in this paper (▪).…”
A novel approach to electrochemistry in thin layers of organic solvents is presented. These layers are formed in situ from benzene, o-dichlorobenzene, or dichloromethane on a hanging mercury drop electrode (HMDE). Very thin organic layers are formed by the expansion of a mercury drop and an organic layer into an aqueous bulk phase. The process of expansion and formation of the thin organic layer on mercury was studied by optical microscopy. Modification of the HMDE by these thin layers of organic solvents significantly limits the reduction of metal ions from the aqueous bulk solution. The redox behavior of C 60 in these thin films is shown to be highly solvent dependent. This dependence is demonstrated by comparison of the cyclic voltammetry of C 60 in a benzene layer with that in an o-dichlorobenzene layer. In the potential range from 0 to -1200 mV, two reversible reduction processes are observed for C 60 . In benzene, with its very low dielectric constant, the electrode processes are complicated by the precipitation of fulleride salts.
“…However, for the alkylammonium ions, it is to be 3Unfortunately, the I-values are not strictly thermodynamic due to the lack of activity coefficient data for salts of the type studied here. This has been a problem also in other work (6)(7)(8)(9)(10)(11)(12). remembered that all the results are obtained in an excess (1 M) of HClO, as supporting electrolyte so that the Debye parameter K is constant with 1 1~ = 0.5 nm, giving a constant shielding effect (18,19) in the interphase region.…”
Section: Resultsmentioning
confidence: 93%
“…Previous studies at electrodes have been concerned with super-equivalent adsorption of symmetrical (6)(7)(8) and unsymmetrical (9) tetraalkylammonium (R4Nf) salts with varying chain length of R while corresponding alkylpyridinium ions have also been examined (10,11). The structure of the doublelayer in the presence of R4N+ ions is of particular 'On leave of absence from the Research Group: "Physicochimie des Interfaces", C.N.R.S., B.P.…”
By means of adsorption and surface-potential studies on a series of R4−nN+Hn perchlorates at the air/water interface, the role of hydrophobic and hydrophilic interaction in the adsorption and ion distribution of these salts near the air/water interface is examined. While the adsorption of the alkylamine ions increases as n decreases from three to zero, inclusive, the surface-potential change accompanying the adsorption decreases. This effect is interpreted in terms of opposing hydrophilic, electrostatic and hydrophobic interactions between the organic ion and water near the liquid surface, leading to a progressive change of double-layer ion distribution. In Part II, comparative studies of the same series of compounds at the Hg/water interface are reported.
“…Nature oS the adsorbable species.~Adsorption of t e t r a a l k y l a m m o n i u m ions onto mercury from aqueous media has been investigated extensively (9)(10)(11)(12)(13)(14). Devanathan and Fernando (9) used a capillary electrometer to examine the behavior of several t e t r aa l k y l a m m o n i u m iodides at 25~ and concluded, for t e t r a m e t h y l a m m o n i u m iodide as well as the other salts, that there exists a mid-cathodic region of potentials within which the cation and anion are both specifically adsorbed and that the cations p r o b a b l y form "bridges" with the anions.…”
At relatively negative potentials and at temperatures below --29~ a prominent current minimum is observed in polarograms for the reduction of alkyl halides in dimethylformamide containing tetramethylammonium per-Present address: Firestone Plastics Company, Pottstown, Pennsylvania 19464.
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