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Selectividad y mecanismos impulsados por la dinámica de reacción: el caso de la reacción en fase gaseosa OH(-) +
Miguel A F de Souza1, Thiago C Correra, José M Riveros
1Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50.740-560 Recife, PE, Brazil.
Journal of the American Chemical Society
|October 31, 2012
Resumen
Las teorías estadísticas no logran explicar la selectividad de la reacción OH(-) + CH(3)ONO(2). Las simulaciones de dinámica directa revelan efectos dinámicos, como la dispersión electrostática, que dictan las relaciones de producto en esta reacción de iones-moléculas en fase gaseosa.
Área de la Ciencia:
- La Dinámica Química es la Dinámica Química.
- Química computacional es la química computacional.
- Mecanismos de reacción Mecanismos de reacción
Sus antecedentes:
- Las teorías estadísticas tradicionales luchan por predecir la selectividad de reacción en sistemas complejos.
- La reacción en fase gaseosa entre el ion hidróxido (OH-) y el nitrato de metilo (CH ((3) ONO ((2)) presenta un desafío debido a las múltiples vías de reacción potenciales.
Objetivo del estudio:
- Para investigar el mecanismo de reacción y la selectividad del producto de OH(-) + CH(3)ONO(2).
- Para aclarar las razones detrás de la selectividad observada utilizando métodos computacionales.
Principales métodos:
- Se emplearon simulaciones de dinámica directa para modelar la reacción.
- Los perfiles de energía potencial de alto nivel se calcularon utilizando enfoques estadísticos establecidos para la comparación.
Principales resultados:
- Las simulaciones reproducían con precisión la relación de producto experimental S(N) 2: E(CO) 2.
- La reactividad en el átomo de nitrógeno fue suprimida por los potenciales electrostáticos negativos del grupo de nitrato, dispersando el ion OH-.
- Se observó un comportamiento no estadístico, atribuido a la falta de complejos equilibrados y efectos de recrudecimiento.
Conclusiones:
- Los efectos dinámicos, en particular las interacciones electrostáticas, son cruciales para comprender la selectividad de esta reacción iónico-molecular.
- Las teorías estadísticas estándar son insuficientes para describir con precisión tales reacciones.
- Se justifica una mayor investigación sobre los efectos no estadísticos en las reacciones iónico-moleculares en la fase gaseosa.
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