Kinetics of electron transfer from nitroaromatic radical anions in aqueous solutions. Effects of temperature and steric configuration

Journal Article · Thu Sep 11 04:00:00 EDT 1986 · J. Phys. Chem.; (United States)

OSTI ID:5241704

Mautner, M M.N.; Neta, P

Rate constants for electron transfer from various nitroaromatic radical anions to other nitroaromatic compounds in aqueous solutions have been determined by kinetic spectrophotometric pulse radiolysis. The rate constants were found to increase from approx. 10/sup 5/ to approx. 10/sup 8/ M/sup -1/ s/sup -1/ upon increase in driving force (..delta..E) from 0 to approx. 300 mV, while the activation energies decrease from approx. 6 to approx. 3 kcal/mol. Nitro compounds with ortho substituents exhibit lower reduction potentials due to rotation of the nitro group away from the ring plane. Anion radicals of such compounds transfer their electrons much more slowly (k down to approx. 10/sup 6/ M/sup -1/ s/sup -1/) despite the apparent increase in ..delta..E (to approx. 550 mV). This behavior is rationalized by an increase in solvent reorganization energies around these radical anions caused by localization of the charge. In general, nitroaromatic radical anions donate electrons much more slowly than other radical anions, in reactions with similar driving forces, due to low self-exchange rates for ArNO/sub 2//ArNO/sub 2//sup -/. The kinetics show no anomalies in supercooled solutions.

• Research Organization: National Bureau of Standards, Gaithersburg, MD
• OSTI ID: 5241704
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:19; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANIONS
AQUEOUS SOLUTIONS
CHARGED PARTICLES
CHEMICAL REACTION KINETICS
CONFIGURATION INTERACTION
DATA
DISPERSIONS
ELECTRON TRANSFER
EXPERIMENTAL DATA
INFORMATION
IONS
KINETICS
MIXTURES
NITRO COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
REACTION KINETICS
SOLUTIONS
TEMPERATURE DEPENDENCE