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Reacciones catalíticas de precursores de carbenos en el oro metálico a granel

Yibo Zhou¹, Brian G Trewyn, Robert J Angelici

¹Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.

Journal of the American Chemical Society

|August 1, 2009

Resumen

El metal dorado en polvo cataliza el acoplamiento de carbenos y las reacciones de ciclopropanación, formando olefinas. El tamaño y la naturaleza de las partículas influyen significativamente en la actividad catalítica, con mecanismos que involucran intermediarios de carbenos adsorbidos en la superficie.

Área de la Ciencia:

* Catálisis heterogénea.
* Química organometálica es una química orgánica.
* Ciencias de la superficie.

Sus antecedentes:

* Las nanopartículas de oro son catalizadores conocidos, pero las propiedades catalíticas del oro a granel son menos exploradas.
* Los diazoalcanos y el 3,3-difenilciclopropeno (DPCP) son precursores comunes del carbeno.
* Los carbenos intermedios son cruciales en varias transformaciones orgánicas.

Objetivo del estudio:

* Para investigar la actividad catalítica del polvo metálico de oro a granel en reacciones mediadas por carbenos.
* Explorar la influencia de las características de las partículas de oro en el rendimiento catalítico.
* Para aclarar los mecanismos de reacción involucrados.

Principales métodos:

* Microscopía electrónica de transmisión (TEM) y microscopía electrónica de barrido (SEM) para la caracterización de partículas de oro.
* Reacciones catalíticas utilizando diazoalcanos y DPCP con polvo de oro a granel.
* Análisis de los productos de reacción para determinar la formación de olefinas y ciclopropano.

Principales resultados:

* El polvo de oro a granel (partículas de 5 a 50 micrones) cataliza efectivamente el acoplamiento de carbenos para formar olefinas.
* El polvo de oro también cataliza reacciones de ciclopropanación con estirenos.
* La actividad catalítica se correlaciona con la naturaleza de las partículas de oro, como se observa a través de TEM/SEM.

Conclusiones:

* El polvo metálico de oro a granel es un catalizador eficaz para el acoplamiento de carbenos y la ciclopropanación.
* Las propiedades físicas de las partículas de oro juegan un papel crítico en su función catalítica.
* Los mecanismos de reacción implican carbenos intermedios adsorbidos en la superficie del oro.

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