Pulse radiolytic kinetic study of the decay of. alpha. -methyl-substituted benzoquinone radical anions: A possible mechanistic model for bioreductive alkylation

Journal Article · Wed Jan 16 04:00:00 EST 1991 · Journal of the American Chemical Society; (United States)

DOI:https://doi.org/10.1021/ja00002a032· OSTI ID:5288870

O'Shea, K E; Fox, M A ^[1]

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1. Univ. of Texas, Austin (USA)

Pulse radiolysis and transient absorption spectroscopy were used to kinetically characterize the decay of several {alpha}-methyl-substituted 1,4-benzoquinone radical anions. Electron attachment rates, absorption spectra, extinction coefficients, and pK{sub a}'s for the reduced quinones are very similar regardless of substituent, but the decay kinetics are dependent on both substituent and pH. The semiquinone radical anions disproportionate at pH 7 regardless of substituent. At pH 3, the radical anion is readily protonated, and in the phenoxy- and methoxy-substituted models reductive elimination becomes competitive with disproportionation. The involvement of an intramolecular H-bonded intermediate is proposed in the formation of the quinone methide. The existence of such an intermediate is supported by theoretical results (AM1 calculations).

• OSTI ID: 5288870
• Journal Information: Journal of the American Chemical Society; (United States), Journal Name: Journal of the American Chemical Society; (United States) Vol. 113:2; ISSN 0002-7863; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ALKYLATION
ANIONS
AROMATICS
BENZOQUINONES
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
EXPERIMENTAL DATA
INFORMATION
IONS
MEASURING METHODS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
QUINONES
RADIATION EFFECTS
RADIOLYSIS
SPECTROSCOPY