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A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes
Published on: February 27, 2017
Síntesis de un naftaleno extremadamente abarrotado a través de una norbornadienona estable
1Department of Chemistry, Princeton University, Princeton, NJ 08544, USA.
Journal of the American Chemical Society
|November 1, 2001
Resumen
Se investigaron derivados de naftaleno muy concurridos. El estudio encontró que mientras que el 5,6,8-tri(tert-butil)-1,2,3,4-tetrafenilnaftaleno exhibe una estabilidad inusual, los análogos más congestionados pueden formar isómeros de Dewar, lo que afecta la estructura química y la estabilidad.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química computacional es la química computacional.
- La cristalografía es una técnica de cristalografía.
Sus antecedentes:
- Investigando los límites de la congestión estérica en sistemas aromáticos.
- Comprender la estabilidad de los hidrocarburos aromáticos policíclicos altamente sustituidos.
Objetivo del estudio:
- Para sintetizar y caracterizar derivados de naftaleno estéricamente obstaculizados.
- Explorar la relación entre el obstáculo estérico y la estabilidad molecular.
- Para investigar el potencial para la formación de isómeros de Dewar en los naftalenos abarrotados.
Principales métodos:
- Estudios computacionales utilizando los métodos Hartree-Fock (HF) y la Teoría Funcional de la Densidad (DFT) (HF/3-21G, B3LYP/6-31G(d)).
- Síntesis química que involucra las reacciones del tetrafenilbenzino con la tri-ter-butilo-ciclopentadienona.
- Cristalografía de rayos X para la determinación estructural de compuestos sintetizados.
- Análisis térmico para evaluar la estabilidad del compuesto y las vías de descomposición.
Principales resultados:
- Se sintetizó y estudió un derivado de naftaleno muy concurrido, el 5,6,8-tri(tert-butil)-1,2,3,4-tetrafenilnaftaleno.
- Se formó y caracterizó un inesperado intermediario estable de norbornadienona, el 1,2,4-tri(tert-butilo) -5,6,7,8-tetrafenil-9-oxo-1,4-dihidro-1,4-metanoftaleno.
- Las altas energías de activación para la descarbonización del intermediario se determinaron experimental y computacionalmente, lo que indica una tensión significativa.
- El derivado de naftaleno objetivo mostró distorsiones geométricas excepcionales, pero una estabilidad térmica limitada, descomponiéndose al calentarse prolongadamente.
Conclusiones:
- El obstáculo estérico tiene un impacto significativo en la estabilidad y las formas isoméricas preferidas de los derivados de naftaleno.
- Los naftalenos altamente congestionados pueden existir preferentemente como isómeros de Dewar en lugar de estructuras normales de naftaleno.
- La síntesis y caracterización de las moléculas tensadas proporcionan información sobre los límites de la unión química y la arquitectura molecular.
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