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Catalizador Tetraédrico Oxo-Sn con soporte: Sitio único, dos modos de catálisis

Evgeny V Beletskiy, Xianliang Hou¹, Zhongliang Shen

¹Northwestern Polytechnical University , Xi'an, Shaanxi 710072, PR China.

Journal of the American Chemical Society

|March 18, 2016

Resumen

Un nuevo catalizador heterogeneizado con centros de estaño (Sn) injertados en sílice exhibe doble acidez de Lewis y Brønsted. Este versátil catalizador de ácido sólido cataliza eficientemente la transferencia de hidruro, la apertura del anillo epóxido y las reacciones de acetalización.

Área de la Ciencia:

Catálisis heterogénea
Ciencias de los materiales
Química orgánica de los metales

Sus antecedentes:

Los catalizadores homogéneos a menudo sufren problemas de separación y reciclaje.
El injerto de complejos metálicos en soportes sólidos ofrece una ruta a catalizadores heterogeneizados.
Los silsesquioxanos oligoméricos poliédricos (POSS) pueden servir como ligandos efectivos para los centros metálicos.

Objetivo del estudio:

Desarrollar un catalizador estable y heterogeneizado basado en estaño.
Investigar la actividad catalítica y las propiedades ácidas del catalizador soportado.
Para explorar su potencial en varias transformaciones orgánicas.

Principales métodos:

Síntesis de un complejo (POSS) -Sn-POSS injertado en sílice.
Calcinación leve en el ozono para generar el catalizador heterogeneizado.
Caracterizaciones espectroscópicas: EXAFS, RMN, UV-vis y DRIFT.
Envenenamiento estequiométrico por piridina para la cuantificación del centro de Sn.
Pruebas de actividad catalítica en la transferencia de hidruro, apertura del anillo epóxido y acetalización.

Principales resultados:

El catalizador heterogeneizado mantuvo la coordinación tetraédrica del precursor homogéneo.
Los datos espectroscópicos confirmaron los centros de estaño (Sn) accesibles y uniformes.
El catalizador demostró actividad como un ácido de Lewis sólido en las reacciones de transferencia de hidruro.
Los centros de estaño exhibieron acidez de Brønsted al interactuar con los alcoholes, lo que permitió nuevas vías catalíticas.

Conclusiones:

La calcinación leve generó con éxito un catalizador de estaño robusto y heterogeneizado.
El catalizador posee ambos sitios ácidos de Lewis y Brønsted.
Esta doble acidez permite diversas aplicaciones catalíticas, incluida la transferencia de hidrógeno, la apertura del anillo epóxido y la acetalización.

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