Thiyl radical interaction with pyrimidine C5-C6 double bond.
Addition and elimination interaction of thiyl radicals with the C5-C6 double bond in pyrimidines was studied by the pulse radiolysis technique in aqueous solution with the use of different monitoring systems. For this purpose, p-thiocresol, cysteamine hydrochloride, and mercaptoethanol were used. The rate constants of addition and elimination of thiyl radicals were determined by applying the modified version of ACUCHEM (computer program for modeling complex reaction systems). Aliphatic thiyl radicals add to the pyrimidine C5-C6 double bond with k = 1.0-3.0 x 10(7) dm3 mol(-1) s(-1), whereas elimination takes place with k = 0.7-2.0 x 10(5) s(-1). Quantum chemical calculations at the B3LYP/6-31G(d)/PCM level show that the addition should occur at the C6 position of the pyrimidine ring and that the energy of interaction between thiyl radicals and the pyrimidine double bond C5-C6 is low.
Wójcik
Aleksandra
A
University of Leipzig, Interdisciplinary Group for Time-Resolved Spectroscopy, Permoserstr. 15, 04303 Leipzig, Germany.
Naumov
Sergej
S
Marciniak
Bronisław
B
Hermann
Ralf
R
Brede
Ortwin
O