Intramolecular electron transfer and dehalogenation of anion radicals. 2. Halonitroaromatic compounds

Journal Article · Thu Mar 19 04:00:00 EST 1981 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150606a016· OSTI ID:6507546

Behar, D; Neta, P

Halonitroaromatic compounds were reduced with e/sub aq//sup -/ or (CH/sub 3/)/sub 2/COH in irradiated aqueous solutions to produce the anion radicals. The decay of these radicals follows either a bimolecular radical radical reaction or a unimolecular dehalogenation. The influence of the halogen location relative to the ring and the nitro group, and the effect of the C-halogen bond strength on the rates of the unimolecular dehalogenation were examined. p-ClC/sub 6/H/sub 4/NO/sub 2//sup -/, m-BrC/sub 6/H/sub 4/NO/sub 2//sup -/, o- and p-IC/sub 6/H/sub 4/NO/sub 2//sup -/, p-BrCH/sub 2/CH/sub 2/C/sub 6/H/sub 4/NO/sub 2//sup -/, p-ClCH/sub 2/COOC/sub 6/H/sub 4/NO/sub 2//sup -/, p-ClCH/sub 2/CONHC/sub 6/H/sub 4/NO/sub 2//sup -/, and p-ClCH/sub 2/CH/sub 2/OCH/sub 2/CH/sub 2/OC/sub 6/H/sub 4/NO/sub 2//sup -/ all decayed by second-order processes. The lack of dehalogenation reaction in these anion radicals is rationalized by high bond dissociation energies in the case of the halonitrobenzene radical anions, and by weak interactions of the halogen atom in the other compounds with the unpaired electron residing mainly on the nitrobenzene ring. p-ICH/sub 2/COOC/sub 6/H/sub 4/NO/sub 2//sup -/ decays unimolecularly with k = 30 s/sup -1/ reflecting the low C-I bond strength. m- and p-BrCH/sub 2/COC/sub 6/H/sub 4/NO/sub 2//sup -/ decay in unimolecular processes with rates of 1.5 x 10/sup 2/ and 4.1 x 10/sup 4/ s/sup -1/, respectively. These relatively high rates are rationalized by weakening of the C-Br bond by the CO group and by an effective bridging by the CO for intramolecular electron transfer.

• Research Organization: Univ. of Notre Dame, IN
• OSTI ID: 6507546
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 85:6; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
AQUEOUS SOLUTIONS
AROMATICS
CHEMICAL RADIATION EFFECTS
CHEMISTRY
CHLORINATED AROMATIC HYDROCARBONS
DATA
DISPERSIONS
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
GAMMA RADIATION
HALOGENATED AROMATIC HYDROCARBONS
INFORMATION
IONIZING RADIATIONS
KINETICS
LEPTONS
MIXTURES
NITRO COMPOUNDS
NUMERICAL DATA
ORGANIC CHLORINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
REACTION KINETICS
SOLUTIONS
SOLVATED ELECTRONS