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Abstract
Thesis’s title: Solvent and Temperature Effects on the Kinetic of Reactions and Their Reactivity Trends of Some Coumarin Derivatives.
Candidate : Ahmed Mohammed Abu Dief Mohammed
Kinetic results, rate laws and reaction mechanisms were established for the base hydrolysis of 7-hydroxycoumarin (HC), 7-hydroxycoumarin-4-acetic acid (HCA), 6-nitrocoumarin (NC), 6-nitrocoumarin-3-carboxylic acid (NCC), 7-dimethylamino-4-methylcoumarin (DMAC), 7-diethylamino-4-methylcoumarin (DEAC) and coumalic acid (COU) in aqueous solution, water-methanol and water-acetone mixtures. The kinetics of the base hydrolysis followed a rate law with kobs= k2[OH-] for all coumarin derivatives under study except 6-nitrocoumarin-3-carboxylic acid (NCC) which followed a rate law with kobs= k1+ k2[OH-]. The kinetic data leaded to Gibbs free energies of activation (the change in activation barrierδ m∆G#).
The solubilities of the non-charged compounds, HC, NC, DMAC and DEAC in water-methanol and water-acetone mixtures were established and their transfer chemical potentials were calculated. Moreover, the solubilities of calcium and lanthanum salts of HCA, NCC and COU in water-methanol mixtures were established and the transfer chemical potentials of their anions were calculated. Furthermore, the solubilities of cerium and lanthanum salts of HCA, NCC and COU in water-acetone mixtures were established and the transfer chemical potentials of their anions were calculated.
Solvent effect on reactivity trends of the investigated coumarin derivatives have been analyzed into initial and transition state components by using the transfer chemical potentials of the reactants and the kinetic data of the studied compounds.