Resonance Raman studies of pulse radiolytically produced p-aminophenoxyl radical

Journal Article · Thu Apr 26 04:00:00 EST 1984 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j150653a009· OSTI ID:6454382

Tripathi, G N.R.; Schuler, R H

The p-aminophenoxyl radical produced in the pulse radiolytic oxidation of p-aminophenol in aqueous solution has been examined by time-resolved resonance Raman methods. Eight Raman bands of fundamental vibrations were observed at microsecond times and at radical concentrations of -- 10/sup -5/M by excitation in the moderately strong absorption band of this radical at 444 nm (E = 6800 M/sup -1/ cm/sup -1/). This radical decays rapidly by second-order processes (2k = 2 x 10/sup 9/ M/sup -1/ s/sup -1/) so that at times longer than milliseconds the residual signals are very weak. The most intense Raman band of this radical, observed at 1636 cm/sup -1/, is ascribed to the Wilson 8a ring stretching mode and is similar in frequency to this mode in p-benzosemiquinone radical anion (1620 cm/sup -1/). The mixed CO/CN stretching frequency (1434 cm/sup -1/) is also very similar to that of the analogous mode in p-benzosemiquinone. This radical exhibits no strong Raman bands in the region of 1510-1520 cm/sup -1/ as do most other substituted phenoxyl radicals. Deuterium substitution of the NH/sub 2/ group shows that a band at 1673 cm/sup -1/ in the protonated radical is due to the symmetrical NH/sub 2/ bending vibration. Interestingly, this deuterium substitution results in small increases in the frequencies of the CO/CN and ring stretching vibrations. The Raman data show very clearly, in agreement with conclusions from ESR data, that the structure of p-aminophenoxyl radical is more similar to that of a semiquinone than it is that of a phenoxyl radical. The high second-order rate constant observed for decay, however, indicates that the NH/sub 2/ group contributes significantly to modifying the redox properties of this radical.

• Research Organization: Univ. of Notre Dame, IN
• OSTI ID: 6454382
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 88:9; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400302 -- Organic Chemistry-- Isotope Effects-- (-1987)
400600* -- Radiation Chemistry
AQUEOUS SOLUTIONS
AROMATICS
CHEMICAL RADIATION EFFECTS
CHEMISTRY
DATA
DEUTERIUM
DISPERSIONS
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
INFORMATION
IRRADIATION
ISOTOPE EFFECTS
ISOTOPES
LEPTONS
LIGHT NUCLEI
MIXTURES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHENOLS
PULSED IRRADIATION
RADIATION CHEMISTRY
RADIATION EFFECTS
RAMAN EFFECT
RAMAN SPECTRA
SOLUTIONS
SPECTRA
STABLE ISOTOPES