First direct observation of reversible oxygen addition to a carotenoid-derived carbon-centered neutral radical,

Abstract:Direct observation of reversible oxygen addition to a carotenoid-derived carbon-centered neutral radical is reported for the first time. The influence of temperature on the observed reaction kinetics has been used to obtain kinetic and thermodynamic parameters relating to the reversible addition of oxygen to the carotenoid radical obtained from reaction of 7,7′-dihydro-b-carotene (77DH) with phenylthiyl radical (PhS^•) in benzene. In addition, the rate constant for oxygen addition to the equivalent b-carotene(b-CAR) derived radical is also reported.