Phenolic hydrogen abstraction by the triplet excited state of thiochromanone: a laser flash photolysis study

Journal of the Brazilian Chemical Society

Alessandra M. Ribeiro²  Ada Ruth Bertoti¹  José Carlos Netto-ferreira² 

[1] ,Universidade Federal Rural do Rio de Janeiro Instituto de Ciências Exatas Departamento de QuímicaSeropédica RJ ,Brazil

关键词: thiochromanone;    laser flash photolysis;    triplet excited state;    hydrogen donors;   

DOI  :  10.1590/S0103-50532010000600017

来源: SciELO

【 摘 要 】

Triplet ketones are known to oxidize biological substrates which can lead to damage of several biomolecules such as amino acids, nucleosides and DNA. As part of our systematic study on the interaction between carbonyl compounds and phenols, the triplet reactivity of thiochromanone (1) towards substituted phenols, in acetonitrile, was investigated employing the laser flash photolysis technique. The quenching rate constants ranged from (1.1 ± 0.1) × 10(8) L mol-1 s-1 (4-cyanophenol) to (5.8 ± 1.0) × 10(9) L mol-1 s-1 (hydroquinone). A Hammett plot for the reaction of triplet 1 with phenols containing polar substituents resulted in a reaction constant ρ = -0.90. This negative value observed for the reaction constant ρ is in accord with a mechanism in which the hydrogen transfer from phenols to the triplet carbonyl involves a coupled electron/proton transfer.

【 授权许可】

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