61219-63-4Relevant articles and documents
Solvent effects on the reduction mechanism of 9-chloroanthracene, 3-nitrobenzyl chloride and 3-chloroacetophenone
Jensen, Henrik,Daasbjerg, Kim
, p. 1151 - 1164 (2007/10/03)
The reduction mechanism of 9-chloroanthracene, 3-nitrobenzyl chloride and 3-chloroacetophenone has been investigated in detail by means of cyclic voltammetry and controlled potential bulk electrolysis. The investigation was carried out in a number of aprotic solvents in order to elucidate the importance of solvation phenomena on the various parameters associated with the reaction mechanism, i.e., clevage, hydrogen abstraction, protonation and dimerization rate constants as well as standard potentials. In this connection, the influence of the supporting electrolyte in terms of ion pairing and double layer effects has been considered. For the radical anions of 9-chloroanthracene and 3-nitrobenzyl chloride the logarithm of the cleavage rate constant shows a linear dependence on the Gutmann acceptor number and donor number, respectively, whereas no clear-cut correlation can be observed in the case of the radical anion of 3-chloroacetophenone. The rate constant obtained for the protonation reaction between 3-nitrobenzyl anion and 3-nitrobenzyl chloride is to an even higher extent influenced by the nature of the solvent. The trends in the solvent effects are discussed. Acta Chemica Scandinavica 1998.
Kinetic Study for Reactions of Nitrate Radical (NO3.) with Substituted Toluenes in Acetonitrile Solution
Ito, Osamu,Akhido, Seiji,Iino, Masashi
, p. 2436 - 2440 (2007/10/02)
The absolute rate constants for the reactions of the nitrate radical (NO3.) with substituted toluenes in acetonitrile have been determined by the flash photolysis method.From the plots of the rate constants against the ionization energies, it was revealed that the reaction path for toluene derivatives with low ionization energies is different from that for toluene derivatives with high ionization energies.For toluene, a deuterium isotope effect was observed to be ca. 1.6, suggesting the direct hydrogen atom abstraction reaction; in this group, xylenes and p-chlorotoluene belong.For toluene derivatives with electron-withdrawing substit uents, NO3. may add to the phenyl rings followed by successive reactions.For both groups, linear correlations against ionization energies with negative slopes show that NO3. is highly electrophilic and that strong polar effects exist in the transition states of both reactions.For toluenes with methoxy groups, the electron-transfer reaction from methoxytoluene to NO3. is a main initial path, since the transient absorption band due to the cation radical of methoxytoluene was detected.
Theory of Intramolecular Electron Transfer Reactions in Anion Radicals of Nitrobenzyl Halides
Miller, Kristine E.,Kozak, John J.
, p. 401 - 403 (2007/10/02)
Recently, we have suggested a lattice-based theory of chemical reactivity in which quantum and statistical mechanical arguments are combined to yield a method for calculating rate constants for certain classes of reactions.We present here the first concrete application of this theory and calculate the first-order rate constants for dehalogenation of the ortho-, meta-, and para-substituted nitrobenzyl chloride anion radicals.Our theoretical results are obtained by calculating the ? orbital spin populations of the anion radicals (MO calculations using the GAUSSIAN 82 series of programs), using the consequent values to distinguish the ortho, meta, and para sites, and then calculating the rate constants using a lattice statistical approach, the latter based on a theory presented recently.Apart from the limitations of the MO calculations and the neglect of solvent effects, the method involves no further assumptions or parameters.The theoretical estimates are in good agreement with the experimental rate constants.
INTRAMOLECULAR ELECTRON TRANSFER AND DEHALOGENATION OF NITROAROMATIC ANION RADICALS.
Bays,Blumer,Baral-Tosh,Behar,Neta
, p. 320 - 324 (2007/10/02)
A series of nitroaromatic compounds, containing Cl, Br or tosyl groups at various positions, were synthesized and studied by pulse radiolysis in aqueous alcohol solutions. One-electron reduction of the compounds produces the anion radicals which then undergo an intramolecular electron transfer and eliminate X** minus (Cl** minus , Br** minus , or TsO** minus ). The rates of X** minus elimination vary over six orders of magnitude and are affected by the C-X bond dissociation energies, the size and nature of the group bridging the X with the pi system, and the relative positions of these groups. Intramolecular electron transfer through space is also demonstrated. Refs.
Intramolecular Electron Transfer in the Anion Radicals of Nitrobenzyl Halides
Neta, P.,Behar, D.
, p. 4798 - 4802 (2007/10/02)
One-electron reduction of nitrobenzyl halides produces the anion radicals which subsequently undergo intramolecular electron transfer and decompose into nitrobenzyl radicals and halide ions.The optical absorption spectra of the initial anion radicals (λmax ca. 300-310 nm) and the subsequently formed nitrobenzyl radicals (λmax = 359 and 400 for the para and ortho, respectively) are quite intense (ε ca. 104 M-1 cm-1 in most cases) and significantly different.This enables identification of the various species and measurement of the rates of intramolecular electron transfer or C-X bond scission.The rates are 4*103, 1.7*105, and 5.7*105 s-1 for p-nitrobenzyl chloride, bromide, and iodide, respectively.The ortho derivatives decomposed nearly twice as rapidly while the meta decomposed much more slowly.The anion radical of p-nitrobenzyl bromide has pKa = 2.8, and the protonated form is found to undergo the intramolecular transfer ca. 60 times more slowly than the anion radical.The pattern of reactivity of the various anion radicals is rationalized in terms of spin density and charge distribution at the various positions on the ring and in terms of the electrophilicities of the halogens.
