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La reactividad de los alcilos de metallocenos secundarios y la cuestión de los sitios latentes en la polimerización

Clark R Landis¹, Douglass R Sillars, Jeanine M Batterton

¹Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, Wisconsin 53706, USA. landis@chem.wisc.edu

Journal of the American Chemical Society

|July 22, 2004

Resumen

Este estudio revela que las especies secundarias de alquilo de circonio son reactivas, no latentes, con propeno y eteno. Su rápida reacción con el hidrógeno también explica los grupos finales butilo en la hidroligomerización.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
Catálisis de polimerización por catálisis de polimerización.

Sus antecedentes:

Los catalizadores de metaloceno son cruciales en la polimerización de las olefinas.
Anteriormente se debatió el papel de las especies secundarias de alquilo zirconio como sitios inactivos.

Objetivo del estudio:

Para investigar la reactividad de las especies secundarias de alquilo de circonio con olefinas e hidrógeno.
Para aclarar el papel de los alquilos secundarios en las reacciones catalizadas por metaloceno.

Principales métodos:

Espectroscopia de RMN de baja temperatura 1H y 13C en soluciones de tolueno.
Estudio de la reactividad con propeno, eteno e hidrógeno.

Principales resultados:

Los alcilos secundarios de zirconio exhiben una reactividad comparable a los alcilos primarios con propeno y eteno.
Las especies secundarias de alquilo muestran una reactividad significativamente mayor con el hidrógeno (al menos 2 órdenes de magnitud más rápido).
La alta reactividad con el hidrógeno explica la prevalencia de los grupos finales de butilo en la hidroligomerización.

Conclusiones:

Los alcilos secundarios de zirconio no están en estado latente y participan activamente en la inserción de olefinas.
La regioselectividad del catalizador se correlaciona con su capacidad de respuesta al hidrógeno para el control del peso molecular.

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