Generation Of Radical Ions Research Articles

Electrochemical oxidation of substituted 1,4-dihydropyridines in non-aqueous acetonitrile

A series of 29 substituted 1,4-dihydropyridines has been studied in acetonitrile by means of voltammetric methods at a platinum electrode. The formation of radical intermediates has been investigated with the help of ESR spectroscopy. A cell for in situ electrochemical generation of radical ions in ESR measurements has been described. In the detection of radicals a comparison has been made between fast cyclic voltammetry (up to 50 V s −1) at low temperatures (down to −40°C) and ESR spectroscopy. The influence of substituents on oxidation potentials and on oxidation mechanisms has been studied.

Reactivities of organic halides, proton donors and olefins in DMSO towards electrochemically generated radical ions

Reactivities of organic halides, proton donors and olefins in DMSO towards electrochemically generated radical ions

Reactivities of organic halides, proton donors and olefins in DMSO towards electrochemically generated radical ions

Summary The rates of reaction of the radical ions of diethyl fumarate, ethyl cinnamate, stilbene and anthracene, with some organic halides, proton donors and olefins, were measured by cyclic voltammetry. A linear correlation was found between the logarithm of the rate constants and Δ E , the difference in half-wave potential between the electroactive compound and the reactant. Water was an exception, its reactivity is discussed in terms of the charge distribution of the ions.

Effects of halo substituents on electron‐impact induced fragmentation of cyclopropanes

AbstractBromine, fluorine and/or chlorine atoms on one cyclopropyl ring jointly influence the dominant primary modes of electron‐impact induced fragmentation. Decomposition ions include CBrX, C2HQ2X and C3HQ2X2, where × is an halogen atom and Q is from the group of an halogen atom, an hydrogen atom and a methyl group. For none of the compounds studied was formation of an ionic CBrX the dominant primary process. Gem‐dibromo‐gem‐dihalocyclopropanes preferentially eliminated dibromo divalent carbon and formed decomposition products of gem‐dihalogenated C2HQ2X′s. In cases where more stable allyl ions were formed, fragmentation was through C3HQ2X2.Upon electron‐impact, the ions CF, CHF2 and CF3 were produced in abundances directly related to the fluorine content of their cyclopropyl precursors.When fragmentation patterns for internally generated radical ions of the composition C2HQ2X were compared with patterns obtained by direct introduction of the same fluoroolefins into a mass spectrometer, incomplete correspondence was found. Variation in the mode of decomposition can be a consequence of differences in the energy levels of the olefin fragmented.Addition of two hydrogen atoms from water to quinones and to s‐tetrazines is well established in the literature. Reaction of an additional cyclic series, polyhalocyclopropanes, with water prior to electron‐impact is suggested.

Untersuchung des Einflusses von Leitsalz auf die ESR-Spektren neutraler und geladener Radikale in flüssigen Kristallen

Abstract In the course of an investigation of electrolytically generated radical ions in the nematic mesophase of liquid crystals, we studied the influence of supporting electrolyte on the degree of molecular ordering. In the case of the radical anion of tetracyanoethylene (TCNE-) electrolytic generation results in a lower degree of ordering than chemical generation with sodium iodide. By using the neutral radical perinaphthenyl as a probe it was assured that the degree of ordering of the solvent is not disturbed by adding 0.1-m. tetrapropylammoniumperchlorate. A pronounced linewidth variation is observed for the chemically generated TCNE- which is attributed to spin density modulation by dynamic interaction with the Na+ counter ion.

Effect of oxygen on the generation of radical ions by synthetic zeolites

Effect of oxygen on the generation of radical ions by synthetic zeolites

Electron Paramagnetic Resonance and Electrochemistry. Studies of Electrochemically Generated Radical Ions in Aqueous Solution.

Electron Paramagnetic Resonance and Electrochemistry. Studies of Electrochemically Generated Radical Ions in Aqueous Solution.

Additions and Corrections-Electrolytic Generation of Radical Ions in Aqueous Solution

Additions and Corrections-Electrolytic Generation of Radical Ions in Aqueous Solution