22544-62-3Relevant academic research and scientific papers
SPIN-POLARIZED TRANSIENT RADICALS FROM p-BENZOQUINONE AND DI-t-BUTYL-p-QUINONES BY PHOTO-EXCITATION OF BENZOPHENONE IN A MAGNETIC FIELD
Kaise, Masahiro,Nishihara, Chizuko,Nozoye, Hisakazu,Someno, Kazuo
, p. 589 - 592 (1986)
In the photochemical electron transfer reactions of t-alkylamine and p-benzoquinone in liquid, emissively spin-polarized transient anion radicals from p-benzoquinone (PBQ) and 2,5- or 2,6-di-t-butyl-p-quinone (25Q or 26Q) are exclusively produced by photo-excitation of benzophenone (BP) in a magnetic field.Transient radicals of quinones with different unpaired spin distribution are obtained at the onset of photolysis.
1,4-Naphthoquinones, XXV: Reaction of the redox 5-lipoxygenase inhibitor 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone with O2.- and 3O2
Wurm,Damerau,Duchstein
, p. 451 - 455 (1995)
The 5-lipoxygenase inhibitor 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone, its deoxygenation product 1 as well as the oxygenated species 3 are O2.- quenchers with different power in aqueous solution. In alcoholic solution the antioxidative capacity of 1 does not change, 2 indeed is still only a weak O2·- quencher while 3 shows prooxidative properties. This phenomenon was explored in the O2·- generating oxygenation system (OS) DMSO-CO32--O2 by preparative techniques. The following reaction sequence could be proven: 3 → 2 → 4 (2,6-di-tert-butyl-1,4-benzoquinone). While the step 3 → 2 would be O2·- dependent the transition 2 → 4 occurs on two levels: 1. retro Michael reaction with release of 2,6-di-tert-butylphenol, 2. base catalysed oxygenation of 5 → 4 by 3O2. The diphenoquinone 6 occurring as byproduct is split with the OS - in contrast to the reaction with 1O2 - in considerable yield to give 4.
Application of Time-Resolved Chemically Induced Dynamic Electron Polarization and Electron Spin Resonance Techniques to the Quenching of Quinone Triplets by Organometal Donors
Chen, K. S.,Wan, J. K. S.,Kochi, J. K.
, p. 1726 - 1731 (2007/10/02)
Time-resolved CIDEP is successfully applied to the quenching of carbonyl triplets generated photochemically from various quinones.Organometals as quenchers yield paramagnetic organometal adducts of quinones, the ESR parameters and T1 relaxation times of which are reported.An electron-transfer mechanism for the quenching of carbonyl triplets by organometals used in this study is derived from their low ionization potentials similar to those of amines.As such, it can be directly related to organometals as electron donors in thermal processes, in which electron transfer has been shown independently by the deliberate photochemical pumping of the charge-transfer band.The time-resolvced CIDEP technique allows the very short T1 spin-lattice relaxation times to be measured for various organometallic radicals.
