Resumo

MARQUEZ, Edgar  e  FLORES, Máryury. Dft study of formation reactions of 2-propenal and 1-hydroxypropan- 2-one from glycerol. Saber [online]. 2013, vol.25, n.4, pp.431-438. ISSN 1315-0162.

The gas-phase dehydration reactions of glycerol to 2-propenal and 1-hydroxypropan-2-one, were examined by meaning of several methods: B3LYP, B3PW91, MW1PW91 y PBEPBE, combined with two basis-set: 6-31G(d,p) and 6-31++G(d,p) using density functional theory (DFT) and the package G09W. The formation of 2-propenal was studied via three stepway reaction: the first step involves a dehydration of secondary hydroxyl group, followed by keto-enol equilibrium reaction, and, finally, a second dehydration. Formation of 1-hidroxypropan-2-one was studied through a stepway reaction that involves a first dehydration of primary hydroxyl group and, finally, a keto-enol equilibrium reaction. Theoretical results suggest the first dehydration is the limiting-step in the two studied reactions. The important step in the limiting stage was the polarization of C-OH bond, which is assisted for b-Hydrogen atom. Thermodynamics and kinetics parameters, NBO calculations and charge distribution along the transition state, suggest that all hydroxyl groups occurring in the glycerol molecules are kinetically equivalent; thus, selectivity of molecular glycerol decomposition is depending of equilibrium keto-enol rate in the second step of both reactions.

Palavras-chave : Dehydration; transition state; NBO.

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