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Copolimización asimétrica alterna de óxido de ciclohexeno y CO2 con complejos diméricos de zinc
Koji Nakano1, Kyoko Nozaki, Tamejiro Hiyama
1Department of Chemistry and Biotechnology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Journal of the American Chemical Society
|May 2, 2003
Resumen
Los complejos diméricos de zinc catalizan la copolimerización del óxido de ciclohexeno y el CO2. Las modificaciones en la estructura del complejo de zinc aumentaron la actividad catalítica y la enantioselectividad en este proceso de polimerización.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- La ciencia de los polímeros es la ciencia de los polímeros.
- La catálisis es la catálisis.
Sus antecedentes:
- La copolimización alternada asimétrica de epoxidos y CO2 es crucial para la síntesis de policarbonatos funcionales.
- Los complejos de zinc se exploran ampliamente como catalizadores para la utilización de CO2 en reacciones de polimerización.
- Comprender el papel de la estructura del catalizador en el control de la actividad y la selectividad es esencial.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos de zinc dimérico para la copolimización alternada asimétrica.
- Para investigar el rendimiento catalítico de estos complejos en la copolimización de óxido de ciclohexeno y CO2.
- Para aclarar la relación entre la estructura del catalizador, la actividad y la enantioselectividad.
Principales métodos:
- Síntesis de complejos diméricos de zinc a través de la reacción del dietilzinco con ligandos quirales de pirrolidinilmetanol.
- Caracterización estructural mediante cristalografía de rayos X.
- Evaluación catalítica en copolimización alterna asimétrica utilizando la espectrometría de masas MALDI-TOF para el análisis del producto.
Principales resultados:
- Se sintetizó y caracterizó un nuevo complejo dimérico de zinc (2a), con un anillo de cuatro miembros de Zn2O2.
- El complejo 2a catalizó efectivamente la copolimización del óxido de ciclohexeno y el CO2, produciendo un copolímero con el ligando quiral como grupo iniciador.
- Un complejo modificado (3a-OEt) exhibió una mayor actividad catalítica y enantioselectividad, con un grupo etoxi como especie iniciadora.
Conclusiones:
- Las especies diméricas de zinc son las entidades catalíticas activas para esta reacción de copolimización.
- La estructura del complejo de zinc, incluidos los sustituyentes en el ligando, influye significativamente en el rendimiento catalítico.
- El estudio demuestra una vía para desarrollar catalizadores quirales eficientes para la utilización de CO2 y la síntesis de polímeros.
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