Cyclic voltammetry ammonium ions

Bouchard, G., Carrupt, P. A., Testa, B., Gobry, V., Girault, H. H. The apparent lipophilicity of quaternary ammonium ions is influenced by Galvani potential difference, not ion-pairing a cyclic voltammetry study. Pharm. Res. 2001, 18, 702-708. 

The advantage of using a sacrificial anode has been clearly pointed out. Magnesium was found to be the most convenient, the oxidation of which produces Mg ions which can enter the catalytic cycle to cleave the nickela-cycle intermediate and liberate Ni for further catalytic cycles (Scheme 7). Such a mechanism has been substantiated on the basis of the formation of the nickelacycle and its characterization by cyclic voltammetry. In the absence of Mg (reactions conducted in a divided cell in the presence of ammonium ions) the nickelacycle does not transform and the reaction stops when all the starting nickel compound has been reacted. Upon addition of MgBr2 to an electrochemically prepared solution of the nickelacycle, Ni(II) is recovered [114]. 

The cleavage of primary amines in aprotic solvents, such as acetonitrile or DMF, was studied by cpe, controlled potential coulometry, and cyclic voltammetry 463 The results indicate that at low anode potential the primarily formed radical cation RCH2NH2 dissociates to an alkyl cation RCH2+ and an amino radical NH2 , which subsequently is oxidized to nitrogen. At higher anode potentials path a)ofEq. (219), leading to an aldehyde and an ammonium ion, preponderates. 

The effect of temperature on ion transfer across the water-nitrobenzene interface was studied for a series of six quaternary ammonium and phosphonium cations and two anions using cyclic voltammetry and equilibrium impedance measurements [115]. Standard entropies (A S ) and enthalpies (A iT ) of ion transfer have been evaluated from the experimentally accessible reversible half-wave potential ( "572 and standard Gibbs energy of transfer (A G ),... 

It was in 1990 that Kratschmer et al. [217,218] reported the first macroscopic preparation of in gram quantities by contact-arc vaporization of a graphite rod in a 100 Torr atmosphere of helium, followed by extraction of the resultant soot with toluene. Fullerene ions could also be detected by mass spectrometry in low-pressure hydrocarbon flames [219]. The door was opened by, Kratschmer and co-workers preparative success to extensive studies of the electrochemical behavior of the new materials. Cyclic voltammetry of molecular solutions of Ceo in aprotic electrolytes, e.g., methylene chloride/quatemary ammonium salts, revealed the reversible cathodic formation of anionic species, the radical anion, the dianion, etc. (cf. [220,221]). Finally, an uptake of six electrons in the potential range of 1-3.3 V vs. SHE in MeCN/toluene at — 10°C to form the hexavalent anion was reported by Xie et al. [222]. This was in full accordance with MO calculations. A parametric study of the electroreduction of Cgo in aprotic solvents was performed [223]. No reversible oxidation of C o was possible, not even to the radical cation. However, the stability of di- and trications with special counterions, in the Li/PEO/C 3 MoFf cell, was claimed later [224]. 

The various tunable properties of zeolites have inspired a great variety of concepts in electrochemistry with zeolite-modified electrodes. For example, silver ions inside the zeolite pore system arc not electrochemically active in amperometric detection. Flowever, indirect analyte detection can occur when the analyte causes the removal of silver ions into the solution where they are electrochemically detected.[94] This indirect approach was extended to different copper-exchanged zeolites and demonstrated for the detection of several non-elcctroactive ions including alkali metal, ammonium and calcium.[95] A zeolite-modified electrode (ZME) with high selectivity towards Pb over Cd in cyclic voltammetry was prepared via electrophoretic deposition of zeolite Y, coated with Nafion.[96]... 

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