20143-63-9Relevant academic research and scientific papers
Laser flash photolysis studies on the first superoxide thermal source. First direct measurements of the rates of solvent-assisted 1,2-hydrogen atom shifts and a proposed new mechanism for this unusual rearrangement
Konya, Klara G.,Paul, Thomas,Lin, Shuqiong,Lusztyk, Janusz,Ingold
, p. 7518 - 7527 (2007/10/03)
The thermal decomposition of bis(4-carboxybenzyl)hyponitrite (SOTS-1) in aerated water under physiological conditions has previously been shown to give the superoxide radical anion in a yield of 40 mol % (Ingold, K. U.; et al. J. Am. Chem. Soc. 1997, 119, 12364). The absolute kinetics of the elementary reactions involved in the cascade of events leading from the first-formed water-soluble benzyloxyl radical to superoxide have been determined by laser flash photolysis. On the basis of these kinetics it is concluded that SOTS-1 will be suitable for studies of superoxide-induced oxidative stress in most biological systems. A water-assisted 1,2-H shift converting benzyloxyl into the benzyl ketyl radical is an important step in the above reaction cascade. The kinetics of the 1,2-H shift assisted by H2O, D2O, and a number of nucleophilic alcohols have been measured for the first time. These data have led to a proposed new mechanism involving the initial formation of a ketyl radical anion and an oxonium cation which generally collapse to give the neutral ketyl radical as the first observable product on the time scale of our experiments (ca. 80 ns).
REACTIVE ION PAIRS FROM THE CHARGE-TRANSFER EXCITATION OF ELECTRON DONOR-ACCEPTOR COMPLEXES
Masnovi, J. M.,Kochi, J. K.,Hilinski, E. F.,Rentzepis, P. M.
, p. 1126 - 1135 (2007/10/02)
Excitation within the charge-transfer (CT) band of the electron donor-acceptor or EDA complexes of tetranitromethane (TNM) with a series of 9-substituted and 9,10-disubstituted anthracenes (An) leads to photochemistry in high quantum yields (Φ ca. 1).The combined use of time-resolved picosecond spectroscopy, product isolation, and structure elucidation allows for the detailed mapping of the temporal evolution of the CT excited state to the photoproduct I via series of discrete reactive intermediates.Thus electron transfer within the EDA complex occurs effectively (+. and TNM-..The latter is not observed directly owing to its spontaneous fragmentation to C(NO2)3- and NO2 within 10 ps.The geminate ionic intermediates An+. and C(NO2)3-. undergo cage combination to produce hydranthryl radicals II within an interval of /= 1 ns and the trans stereochemistry required for the free radical coupling to occur.This detailed study is the basis for a generalized formulation (summarized in Scheme I) to be developed for CT photochemistry via reactive ion pairs.In particular, the comparison with the related EDA complexes of the anthracenes and tetracyanoethylene serves to emphasize the importance of back electron transfer from the geminate ion pair, i.e., +., A-.> -> .
