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Catálisis dual para la polimerización selectiva de apertura de anillos de lactonas: evolución hacia la simplicidad

Stefan Naumann¹, Philip B V Scholten¹, James A Wilson¹

¹Department of Chemistry, University of Warwick , CV4 7AL Coventry, U.K.

Journal of the American Chemical Society

|October 28, 2015

Resumen

Los ácidos de Lewis simples combinados con organocatalisadores catalizan eficientemente la polimerización de apertura de anillo (ROP) de las macrolactonas. Este enfoque de catálisis cooperativa ofrece control sobre la estructura y las propiedades del polímero utilizando precursores de bajo costo.

Área de la Ciencia:

Química de los polímeros
Catálisis
Síntesis orgánica

Sus antecedentes:

La polimerización de apertura de anillo (ROP) tradicionalmente se basa en catalizadores complejos de un solo sitio.
La catálisis cooperativa que utiliza ácidos de Lewis y organocatalizadores presenta una alternativa más simple y eficaz para la ROP.

Objetivo del estudio:

Investigar el efecto cooperativo de los carbenos N-heterocíclicos (como el DBU y el DMAP) con los ácidos de Lewis para la ROP.
Explorar la selectividad del monómero y el control de la composición del copolímero utilizando este sistema catalítico.

Principales métodos:

Utilizó una combinación de carbenos N-heterocíclicos (DBU, DMAP) y varios ácidos de Lewis (MgX2, YCl3, AlCl3).
Proceso de ROP de la pentadecalactona y otros diésteres cíclicos.
Actividad y selectividad del catalizador analizadas en función de la elección del ácido de Lewis y de la base orgánica.

Principales resultados:

Se ha conseguido una ROP rápida y eficiente de la pentadecalactona utilizando el sistema catalítico cooperativo.
Se ha establecido una clara tendencia de actividad para los ácidos de Lewis: MgX2 ≫ YCl3 ≫ AlCl3 y MgI2 > MgBr2 > MgCl2.
Se ha demostrado la ROP selectiva de monómeros y el control de la composición del copolímero mediante una selección juiciosa del ácido de Lewis.

Conclusiones:

La catálisis cooperativa con ácidos de Lewis simples y organocatalizadores es una estrategia poderosa para la ROP.
Este método permite la síntesis de polímeros complejos con propiedades ajustables a partir de precursores accesibles.
La elección del ácido de Lewis dicta la selectividad del monómero, lo que permite un control preciso de la arquitectura del polímero.

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