Kinetic model for autoxidation of beta-carotene in organic solutions

Autoxidation of beta-carotene was studied experimentally using n-decane as a solvent under various reaction conditions of temperature and dissolved ox ygen concentration. A novel kinetic model was proposed on the basis of an a utocatalytic free-radical chain reaction mechanism. A secondary initiation reaction by decomposition of hydroperoxide and reactions concerned with a b eta-carotene-derived C-centered radical in propagation and termination proc esses were taken into consideration in the model. There were four unknown k inetic constants, and the constants were estimated by fitting the model wit h the experimental data. The fitted results are in good agreement with the experimental data in all stages of the kinetics of autoxidation and over a wide range of oxygen concentrations. The model described not only the appea rance of the induction stage but also the effect of the oxygen concentratio n on the autoxidation rate. In addition, the model predicted the behavior o f autoxidation in another solvent at low temperature that had been reported by other researchers.