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Conversión fotocatalítica de nitrobenzeno a anilina a través de transferencias secuenciales de un electrón acoplado a

Stephen C Jensen¹, Stephanie Bettis Homan¹, Emily A Weiss¹

¹Department of Chemistry, Northwestern University , 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States.

Journal of the American Chemical Society

|January 20, 2016

Resumen

Los puntos cuánticos de sulfuro de cadmio convierten eficientemente el nitrobenzeno en anilina usando luz visible. Las condiciones ácidas evitan el envenenamiento del catalizador, manteniendo una alta actividad durante períodos prolongados.

Área de la Ciencia:

Fotocatálisis
Los puntos cuánticos
Síntesis orgánica

Sus antecedentes:

La fotocatálisis con luz visible ofrece una ruta sostenible para las transformaciones químicas.
Los puntos cuánticos de sulfuro de cadmio (CdS QD) son fotocatalizadores semiconductores prometedores.
La reducción eficiente de los nitroaromáticos a las anilinas es crucial en la síntesis química.

Objetivo del estudio:

Investigar el uso de CdS QD para la reducción de nitrobenzeno a anilina impulsada por luz visible.
Para aclarar el mecanismo de las transferencias de electrones fotoinducidas, acopladas a protones.
Optimizar las condiciones de reacción para una actividad y rendimiento sostenidos del catalizador.

Principales métodos:

Irradiación de nitrobenzeno con luz visible con CdS QD en presencia de ácido 3-mercaptopropiónico.
Espectroscopia de absorción transitoria para monitorear la dinámica del excitón QD y la transferencia de electrones.
Espectroscopia de resonancia magnética nuclear (RMN) para analizar las interacciones entre QD y moléculas y la adsorción del producto.

Principales resultados:

Se ha conseguido una reducción eficiente del nitrobenzeno a la anilina con un rendimiento cuántico interno del 37,1% durante 54 horas.
Identificación de la eliminación rápida de agujeros por el ácido 3-mercaptopropiónico (∼5 ps) y la posterior transferencia de electrones en la escala de tiempo de nanosegundos.
Se ha demostrado que el pH ácido (3.6-4.3) previene el envenenamiento por anilina promoviendo la desorción y facilitando la transferencia de protones.

Conclusiones:

Los CdS QD son fotocatalizadores eficaces de luz visible para la reducción del nitrobenzeno.
El mecanismo de reacción implica transferencias secuenciales de electrones acoplados a protones, con una transferencia de electrones que potencialmente limita la velocidad.
La optimización del pH es fundamental para la estabilidad del catalizador y la conversión eficiente del nitrobenzeno a la anilina.

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