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Sodium Alkyl ((trimethylsilyl) amides: Estructuras y reactividades de las soluciones dependientes del sustituto y del

Qiulin You¹, Yun Ma¹, Ryan A Woltornist¹

¹Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, United States.

Journal of the American Chemical Society

|October 24, 2024

Resumen

Este estudio detalla la síntesis y el análisis estructural de compuestos de amida de sodio, revelando la agregación y la reactividad dependientes del disolvente. Los éteres de la corona influyen en el comportamiento de la amida de sodio, y el 15-crown-5 resulta menos efectivo de lo esperado.

Área de la Ciencia:

Química organometálica
Química del estado de solución
Espectroscopia y Química Computacional

Sus antecedentes:

Los compuestos de amida de sodio son cruciales en la síntesis orgánica.
Comprender su agregación y solución es clave para controlar la reactividad.
Los estudios anteriores a menudo asumieron comportamientos de solvatación específicos.

Objetivo del estudio:

Sintetizar y caracterizar nuevos compuestos de amida de sodio, incluidos los isotopólogos.
Investigar el comportamiento de agregación y solvación de estas amidas en diversos disolventes y con éteres de corona.
Para dilucidar las relaciones estructura-reactividad en las reacciones de aminolisis mediadas por estas amidas.

Principales métodos:

Síntesis de isopropilo de sodio (NaPTA), de amido de sodio (NaPETA) y de amido de sodio (NaBTA).
Estudios estructurales de la solución mediante espectroscopia de RMN 29Si, método de variaciones continuas y cálculos DFT.
Estudios cinéticos cuantitativos de las reacciones de aminolisis y la complejación del éter de corona.

Principales resultados:

Se prepararon NaPTA, NaPETA y NaBTA, junto con sus isotopólogos 15N.
Se determinaron los equilibrios dimer-monómero y los números de solvación para varios disolventes y éteres de corona, mostrando la dependencia del sustituto y el disolvente.
Los estudios de tasa revelaron una variación de 47.000 veces en las tasas de aminolisis, con mecanismos basados en dímeros en tolueno y THF, y comportamientos distintos para las especies solvadas con PMDTA y diglime.

Conclusiones:

La disolución y la agregación tienen un impacto significativo en la reactividad de la amida de sodio.
La eficacia del éter de corona varía, siendo el 15-crown-5 menos efectivo de lo previsto para acelerar las reacciones mediadas por sodio.
Se obtuvieron conocimientos mecanicistas detallados sobre las reacciones de aminolisis, destacando la importancia de las capas de solvación primaria y secundaria.

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