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Síntesis, estructura y actividad de iniciadores mejorados para la metátesis de olefinas
Jennifer A Love1, Melanie S Sanford, Michael W Day
1Arnold and Mabel Beckman Laboratories for Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
Journal of the American Chemical Society
|August 14, 2003
Resumen
Los catalizadores de rutenio con diferentes ligandos de fosfina aceleran las reacciones de metátesis de olefinas. Una disociación más rápida de la fosfina de estos catalizadores aumenta las tasas de iniciación para la polimerización de la metátesis de apertura de anillo y la metátesis de cierre de anillo.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La catálisis de la catálisis.
- La ciencia de los polímeros es la ciencia de los polímeros.
Sus antecedentes:
- Los catalizadores basados en rutenio son cruciales para las reacciones de metástasis de olefinas.
- La estructura y el entorno del ligando influyen significativamente en la actividad del catalizador.
- Comprender los mecanismos de iniciación es clave para optimizar el rendimiento catalítico.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos catalizadores de metátesis de olefina de rutenio.
- Investigar el impacto de los ligandos de fosfina en la iniciación y actividad del catalizador.
- Para correlacionar las tasas de disociación de fosfina con la cinética de reacción en ROMP y RCM.
Principales métodos:
- Síntesis de complejos de rutenio con la estructura general (H(2) IMes) ((PR(3)) ((Cl) ((2) Ru=CHPh.
- Estudios cinéticos que miden las constantes de la velocidad de disociación de la fosfina (k(1)).
- Evaluación del rendimiento del catalizador en la polimerización de la metátesis de apertura de anillo (ROMP) y la metátesis de cierre de anillo (RCM).
Principales resultados:
- La preparación del catalizador implica una síntesis en dos pasos a partir de precursores disponibles en el mercado.
- Las tasas de disociación de fosfina aumentan a medida que disminuye la fuerza del donante de fosfina.
- Los complejos que contienen triarilfosfina muestran una iniciación significativamente mejorada en comparación con los análogos PCy.
- Las tasas de reassociación de fosfina no se correlacionan directamente con la electrónica de la fosfina.
- Una disociación más rápida de la fosfina generalmente conduce a una aceleración de las tasas de reacción de metástasis de la olefina.
Conclusiones:
- El diseño del catalizador se puede ajustar modificando los ligandos de fosfina para controlar las tasas de iniciación.
- La disociación optimizada de la fosfina es fundamental para mejorar la eficiencia de las reacciones de metátesis catalizadas por rutenio.
- Estos hallazgos tienen implicaciones tanto para la síntesis orgánica como para la química de polímeros.
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