Intermediates in the reduction of 5-halouracils by e/sub aq//sup -1/. [Pulsed irradiation]
The radical anions of 5-bromo- and 5-iodouracil produced by the reaction of e/sub aq//sup -/ with the halouracils have been observed in nanosecond pulse radiolysis experiments by their optical absorption at 330 nm. They decay with half-periods of 7.0 +- 0.5 and 1.7 +- 0.3 ns. These short lifetimes contrast with the much longer periods observed for the electron adducts to 5-chloro- and 5-fluorouracil (4.9 and > 15 ..mu..s). The uracilyl radical produced by halide elimination from the radical anions has an extinction coefficient not greater than 150 M/sup -1/cm/sup -1/ at 330 nm and no appreciable absorption at wavelengths longer than 310 nm but reacts with 5-bromouracil to form an addition product which has a broad absorption at 365 nm. The rate constant for this latter reaction, (2.66 +- 0.09) x 10/sup 8/ M/sup -1/s/sup -1/, provides a reference against which to compare the rates of competing reactions. The absolute rate constant for abstraction of hydrogen from tert-butyl alcohol by uracilyl radical has been determined to be (2.3 +- 0.2) x 10/sup 7/M/sup -1/s/sup -1/. It is clear that uracilyl radical reacts very rapidly by both addition and abstraction processes, reflecting the sigma character of this radical. 6 figures.
- Research Organization:
- Catholic Univ. of Puerto Rico, Ponce
- OSTI ID:
- 5580930
- Journal Information:
- J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 87:20; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ABSORPTION SPECTRA
ALCOHOLS
ANIONS
ANTIMETABOLITES
AQUEOUS SOLUTIONS
AZINES
BROMOURACILS
BUFFERS
BUTANOLS
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
CHEMISTRY
DATA
DECAY
DECOMPOSITION
DISPERSIONS
DRUGS
ELECTRONS
ELEMENTARY PARTICLES
EXPERIMENTAL DATA
FERMIONS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
INORGANIC ACIDS
IODOURACILS
IONS
IRRADIATION
KINETICS
LEPTONS
MIXTURES
NUMERICAL DATA
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
PERCHLORIC ACID
PH VALUE
PHOSPHATES
PHOSPHORUS COMPOUNDS
PULSED IRRADIATION
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS
SOLUTIONS
SOLVATED ELECTRONS
SPECTRA
STRUCTURAL CHEMICAL ANALYSIS
TIME DEPENDENCE
URACILS
YIELDS