Browsing by Author "Negusse, Ghebrehiwet"

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    Photochemical and Photophysical Studies on Isatin
    (Addis Ababa Universty, 1983-06) Negusse, Ghebrehiwet; Haucke, G(PhD)
    The fading rate of isatin in different solvents is investigated. the rate is in accordance with the hydrogen - atom donation capacities of the solvents. As the polarity of the solvent is increased the charge transfer character of the longest wavelength transition becomes dominat I'lhich prohobits photo:L'e-· duction. This was confirmed by the red shift of the '118.velenC';:th of maximum absorption with increase in solvent polarity and comparative fading rate of the derivatives of isatin (N - meth;yl isatin and H .- acetyl isatin). Holecular oxygen Vias found to quench the photoreduction. Fluorescence spectrum at different oxygen concentration has been investigated in an attempt to trace the spin state from vlhich the reaction starts. Two photoproducts were separated, the major product (over 95%) \'las characterized to be a pinacol and the second is the product of insertion of a single oxygen to isatin molecule.