Kinetics of hydrolysis and cyclization of ethyl 2-(aminosulfonyl)benzoate to saccharin |
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Authors: | Di Loreto H E Czarnowski J dos Santos Afonso M |
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Institution: | Laboratorio de Compuestos Orgánicos-LADECOM, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Argentina. |
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Abstract: | The cyclization of ethyl 2-(aminosulfonyl)benzoate (ASB) to give saccharin was investigated in aqueous solutions at pH between 5.2 and 9.5 and in the temperature range of 296.2-334.2 K. The initial concentration of the reactant was varied between 1.45 x 10(-5) and 3.86 x 10(-4) M. Ultraviolet spectroscopy was used to obtain the kinetic data. The reaction is acid catalyzed and follows pseudo-first-order kinetics. The experimental rate constant, k(obs), increases with temperature and pH. Its dependence on the temperature and pH is well described by: k(obs) = k1 OH-] = (2.52 +/- 0.9) x 10(16) exp(-20.2 +/- 1 kcalmol(-1)/RT) s(-1)]OH-] A mechanism is proposed and the half-life of ethyl ASB is calculated. |
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