The reactions of tert-butoxyl radicals with resveratrol (1) and two acetylated derivatives (2 and 3) have been investigated by laser. ash photolysis techniques in 1 : 2 (v/v) benzene-di-tert-butyl peroxide at room temperature. The transient absorption spectra of the phenoxyl radicals generated upon H atom abstraction by tert-butoxyl radicals from the phenols have been detected and assigned. The absolute rate constants for these reactions have been evaluated to be 45 x 10(7), 25 x 10(7) and 4 x 10(7) M-1 s(-1) for 1, 2 and 3, respectively. The order of reactivity 1 greater than or equal to 2 >> 3 has been rationalized in terms of the position and effect of the acetyl groups on the aromatic rings. Of the three OH groups present in resveratrol, the one in position 40 appears to be the most reactive due to the large stability of the corresponding phenoxyl radical by conjugation with the rings. However, in our system, the H-atom-donating ability of resveratrol turns out to be inferior to that of alpha-tocopherol by ca. one order of magnitude.

Hydrogen atom abstraction from resveratrol and two lipophilic derivatives by tert-butoxyl radicals. A laser flash photolysis study RID E-4684-2011

Petralia S;TRINGALI, Corrado;SORTINO, Salvatore
2004-01-01

Abstract

The reactions of tert-butoxyl radicals with resveratrol (1) and two acetylated derivatives (2 and 3) have been investigated by laser. ash photolysis techniques in 1 : 2 (v/v) benzene-di-tert-butyl peroxide at room temperature. The transient absorption spectra of the phenoxyl radicals generated upon H atom abstraction by tert-butoxyl radicals from the phenols have been detected and assigned. The absolute rate constants for these reactions have been evaluated to be 45 x 10(7), 25 x 10(7) and 4 x 10(7) M-1 s(-1) for 1, 2 and 3, respectively. The order of reactivity 1 greater than or equal to 2 >> 3 has been rationalized in terms of the position and effect of the acetyl groups on the aromatic rings. Of the three OH groups present in resveratrol, the one in position 40 appears to be the most reactive due to the large stability of the corresponding phenoxyl radical by conjugation with the rings. However, in our system, the H-atom-donating ability of resveratrol turns out to be inferior to that of alpha-tocopherol by ca. one order of magnitude.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/45013
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