Primary processes in the reduction of 4-nitroazobenzene. A pulse radiolysis study in alcoholic solvents
The transient species produced in the reactions of solvated electrons and ..cap alpha..-hydroxyalkyl radicals with 4-nitroazobenzene have been studied by spectrophotometric pulse radiolysis in 2-propanol and methanol. Solvated electrons were found to react with rate constants of 1.6 x 10/sup 10/ and 2.3 x 10/sup 10/ M/sup -1/ s/sup -1/ in 2-propanol and methanol, respectively, giving the anion as primary product. The same species is produced by electron transfer from both alcohol radicals, with rate constants ca. 10/sup 9/ M/sup -1/ s/sup -1/ for (CH/sub 3/)/sub 2/COH and ca. 6 x 10/sup 7/ M/sup -1/ s/sup -1/ for CH/sub 2/OH. Protonation of the anion is observed in the microsecond time scale, leading to the hydrazyl radical. pK values for the protolytic dissociation of this species are evaluated to be 14.8 and 12.3 in 2-propanol and methanol, respectively. Association of the hydrazyl with the starting compound is observed in 2-propanol. Complete reduction of the azo bond occurs by very efficient second-order disproportionation of hydrazyl and/or dimer radicals. 18 references, 7 figures.
- Research Organization:
- Istituto di Fotochimica e Radiazioni d'Alta Energia del CNR, Bologna, Italy
- OSTI ID:
- 5825797
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 90:6; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ALCOHOLS
AROMATICS
AZO COMPOUNDS
BENZENE
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECOMPOSITION
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HYDROCARBONS
HYDROXY COMPOUNDS
INFORMATION
KINETICS
LEPTONS
METHANOL
NITRO COMPOUNDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PROPANOLS
PULSE TECHNIQUES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOLYSIS
REACTION INTERMEDIATES
REACTION KINETICS
REDUCTION
SOLVATED ELECTRONS
SOLVENT PROPERTIES
TRANSIENTS