Studies on the Chemistry of Halogen and of Polyhalides. XIII. Voltammetry of Iodine Species in Acetonitrile

Popov, Alexander I.; Geske, David H.

doi:10.1021/ja01539a018

Cited by 247 publications

(123 citation statements)

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“…The one electron oxidation of halides in acetonitrile solution was proved previously with CPC macroelectrolysis measurements [4]. As seen in the figures, bromide and iodide give double wave using LSV, that can be explained with trihalogenide complex formation, first examined by Popov and Geske [8]. The electrooxidation produces one halide ion from two monomer substrate molecules, therefore the complete coupled halide oxidation should take 0.5 electron/substrate molecule The one electron aniline derivative oxidation takes place by 1 electron/ molecule, thus the expected gross electron consumption of the given halogeno-aniline is 1.5 electron/substrate molecule maximally.…”

Section: Resultsmentioning

confidence: 53%

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The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

2003

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The electrochemical oxidation of 4-chloro-, 2,4-dichloro-, 2,4,6-trichloro-anilines and 4-bromo-, 2,4-dibromo-, 2,4,6-tribromo-anilines and 4-iodo-aniline were investigated in unbuffered acetonitrile solution. The main reaction at the electrooxidation of these compounds is the dimerization which is accompanied by release of the p-substituent halide and formation of protons. To complete the so far achieved results by the apparent electron exchange number (n app ) determination in the voltammetric time scale have been attempted. These measurements were carried out with the aim, to have a clearer picture on the n app influencing role of the following complicating factors: The rejected halogenides in MeCN solvent at lower potential values as the substrates can be oxidized to the corresponding halogens, and these halogens except the iodine substitute the substrate which takes place even in the voltammetric time scale by increasing the n app value characteristic for the dimerization only. The measurable n app values are influenced by the protons produced at the oxidation as well, in the opposite direction. The explanation for the latter is, that the solvent is aprotic, therefore the differently basic primary amino groups of the diffusing substrate molecules binding partly the protons and in this way voltammetrically inactive substrate species are formed. This reaction is a typical equilibrium type and this inactivation effect decrease the measurable n app value. This effect depends on the quality and number of halogene substituent at a given substrate because these affect the protonation constant of the substrate. Therefore the protonation constants of the substrates had to be determined. In the knowledge of these quantitative data the explanation of the trends in the n app values measured in the voltammetric time scale is attempted. The mechanistic study of the dimerization reaction of these substrates is in progress in our laboratory.

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Section: Resultsmentioning

confidence: 53%

“…The titrant was diluted with MeCN from this stock solution just before the titration. The exact concentration of titrant was determined with potassium-hydrogen-phthalate [8]. The titrations were carried out in a titrating glass vessel by joint to avoid traces of water.…”

Section: Chemicalsmentioning

confidence: 99%

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

2003

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“…The chemistry of LiI as a reducing agent in acetonitrile has been studied previously in detail. 17 The oxidation of I Ϫ to I 2 occurs in two reversible steps…”

Section: Methodsmentioning

confidence: 99%

Phase Diagram of Li[sub x](Mn[sub y]Fe[sub 1−y])PO[sub 4] (0≤x, y≤1)

Yamada

Kudo²,

Liu³

2001

J. Electrochem. Soc.

333

381

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The room temperature ͑x, y͒ two-dimensional phase diagram of the olivine-type solid-solution, Li x (Mn y Fe 1Ϫy )PO 4 (0 р x, y р 1, orthorhombic, D 2h 16 : Pmnb), is determined. The x-dependent changes in the unit cell dimensions at various fixed Mn contents y are analyzed in detail. The manganese substitution for iron in the octahedral 4c sites induces 1, the two-phase Mn . The conversion, 2, is complete at around y ϭ 0.6. The phase instability, 3, makes the Mn-rich phase (y Ͼ 0.8) unsuitable for battery applications. The local lattice deformation around Mn 3ϩ is severe enough to induce significant selective damping in the extended X-ray absorption fine structure for Mn The oxidation ͑charge͒ of LiM 2ϩ PO 4 to M 3ϩ PO 4 induces a reduction in the unit cell volume. This shrinkage compensates for the volume expansion of the carbon anodes in the charge process and contributes to efficient use of volume in a practical lithium-ion cell. The opposite movement of lithium ions and electrons occurs during the discharge process, while the transition metal M is reduced from trivalent to divalent.The LiMPO 4 crystal has an orthorhombic unit cell (D 2h 16 , space group Pmnb,) which accommodates four units of LiMPO 4 .11 As a typical example, LiFePO 4 has unit-cell dimensions of a ϭ 6.008(1) Å, b ϭ 10.324(2) Å, and c ϭ 4.694(1) Å. Graphic representations of the crystal structure have been given in many references. 1,3,4,11 Both the Li and M atoms are in octahedral sites with Li located in the 4a and M in the 4c positions. The oxygen atoms are nearly hexagonal closed-packed and the M atoms occupy zigzag chains of corner-shared octahedra running parallel to the c axis in alternate a-c planes. These chains are bridged by corner-and edge-sharing (PO 4 ͒ 3Ϫ polyanions to form a host structure with strong three-dimensional bonding. The Li ϩ ions in 4a sites form continuous linear chains of edge-shared octahedra running parallel to the c axis in the other a-c planes, which makes two-dimensional motion possible.The charge-discharge reaction of the presently used materials, such as the layered rock salt systems, LiCoO 2 , LiNiO 2 ͑space group, R3 m), and a spinel framework system Li 0.5 MnO 2 ͑space groups: Fd3m) are all based on the M 4ϩ /M 3ϩ couple in edge-shared MO 6 octahedra in the closed-packed oxygen array which generates ca. 4 V '' 1,6 The stable nature of the olivine-type structure having a (PO 4 ͒ 3Ϫ polyanion with a strong P-O covalent bond provides not only excellent cycle-life but also a safe system. When the battery is fully charged, the reactivity to the combustion reaction with the organic electrolyte is low.6 Safety issues are of paramount importance in the design of consumer batteries, and this makes olivinetype materials particularly attractive as cathodes for lithium-ion battery systems.The energy density of olivine-type LiMPO 4 is equal to that of presently used materials, based on the theoretical charge-discharge capacity of ca. 170 mAh/g obtained from the M 3ϩ /M 2ϩ one-electron redox reaction of Li x MPO ...

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“…[30][31][32] This study focused on the fi rst reaction because it evidently occurs in DSCs under real working conditions. The CV curve in Figure 4 a for bare FeO x does not show a redox peak in the range between -0.2 and 1.0 V, indicating very low catalytic activity.…”

Section: Doi: 101002/adma201402978mentioning

confidence: 99%

Single‐Atom Catalysis in Mesoporous Photovoltaics: The Principle of Utility Maximization

et al. 2014

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FeOx -supported single Pt atoms are used for the first time as counter electrodes (CEs) in dye-sensitized solar cells (DSCs), which are mesoporous photovoltaic devices. This system enables the investigation of the electrocatalytic behavior of a single-atom catalyst (SAC). Compared with conventional Pt CEs, the SAC-based CEs exhibit better reversibility as indicated by the peak-to-peak separation (Epp ). A high degree of atom utilization is demonstrated.

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Studies on the Chemistry of Halogen and of Polyhalides. XIII. Voltammetry of Iodine Species in Acetonitrile

Cited by 247 publications

References 2 publications

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

The Electrooxidation of Halogeno‐Anilines at Microelectrodes in Acetonitrile Solution

Phase Diagram of Li[sub x](Mn[sub y]Fe[sub 1−y])PO[sub 4] (0≤x, y≤1)

Single‐Atom Catalysis in Mesoporous Photovoltaics: The Principle of Utility Maximization

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