We have characterized the photo – degradation of ẞC in oxygenated and deoxygenated n–hexane solvent and in the solid phase using broadband (BB; λ ≥ 200 nm) and 313 nm filtered output of a 100 W Hg Arc lamp. Oxygen concentrations of 0, 10, 20, and 100% were used in the solution phase studies. ẞC(s) did not photo – degrade upon exposure to BB light under air atmospheres; the mass and appearance of the samples, TLC chromatograms, and the absorption spectra were all identical pre- and post-irradiation. In the solution phase, the order of the photo – degradation with respect to ẞC concentration was of the order ½ ≤ n ≤ ~1 in the presence of O2 and 0th order in the absence of O2. Our results indicate that ẞC(s) photo – degradation proceeds via a different mechanism than ẞC(s) thermal degradation,[1, 2] as the photo – degradation and thermal degradation reactions of ẞC(s) yield different products. These results (i) indicate unequivocally that solvent plays a critical role in the photo – degradation process, and (ii) strongly suggest that solvent radicals resulting from UV irradiation are responsible for the photo – degradation, which is especially important in the absence of O2.[3-5]
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Chemistry | Physical Sciences and Mathematics
Arnold, Katelyn Mary, "Kinetic Characterization of B-Carotene in n-hexane at Various Oxygen Concentrations" (2015). Honors Theses. 49.