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La organocatálisis sinérgica para eliminar la epimerización en las polimerizaciones de apertura de anillos permite la
Maosheng Li1,2, Yue Tao1,3, Jiadong Tang1,3
1Key Laboratory of Polymer Ecomaterials , Changchun Institute of Applied Chemistry, Chinese Academy of Sciences , Renmin Street 5625 , Changchun 130022 , People's Republic of China.
Journal of the American Chemical Society
|December 5, 2018
Resumen
Este estudio introduce un nuevo organocatalisador bifuncional para la polimerización de apertura de anillos de O-carboxianidritos (OCA). Este método logra poliésteres altamente isotácticos sin racemiación monomérica, lo que permite la síntesis sostenible de polímeros funcionales.
Área de la Ciencia:
- Química de los polímeros
- Catálisis orgánica
- Ciencias de los materiales
Sus antecedentes:
- La polimerización por apertura de anillos (ROP) de los O-carboxianidritos (OCA) ofrece acceso a los poliésteres funcionales.
- Los métodos ROP existentes a menudo causan la racemiación monomérica, lo que dificulta la síntesis de polímeros estereorregulares.
- El desarrollo de catalizadores que eviten la epimerización es crucial para la síntesis controlada de poliéster.
Objetivo del estudio:
- Desarrollar un nuevo organocatalisador bifuncional de una sola molécula para la polimerización de OCA.
- Para lograr una ROP selectiva de los OCA sin epimerización.
- Para sintetizar poliésteres altamente isotácticos y explorar sus propiedades.
Principales métodos:
- Diseño y síntesis de un organocatalisador bifuncional de una sola molécula.
- La polimerización por apertura de anillos de los O-carboxianidritos (OCA), específicamente el ácido mandélico OCA (manOCA).
- Caracterización del ácido polimandélico (PMA) resultante, incluido el peso molecular y la táctica.
- Formación y caracterización de los estereocomplejos de PMA.
Principales resultados:
- El catalizador bifuncional permitió una ROP selectiva de manOCA con una epimerización mínima.
- Se sintetizó ácido poli (mandélico) altamente isotáctico (PMA) con pesos moleculares controlados (hasta 19,8 kg mol-1).
- Se formó el primer estereocomplejo cristalino de enantiómeros de PMA, con un punto de fusión de alrededor de 150 °C.
- El catalizador demostró estabilidad a la humedad, reciclabilidad y facilidad de uso.
Conclusiones:
- Un nuevo organocatalisador bifuncional proporciona una ruta eficaz para la ROP estereoselectiva de los AOC.
- Este enfoque permite la síntesis sostenible y escalable de poliésteres funcionales estereorregulares.
- La capacidad de formar estereocomplejos cristalinos abre nuevas vías para los materiales de poliéster funcionales.
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