Video Experimental Relacionado

Updated: Jun 9, 2025

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes

Published on: June 24, 2022

Reducción selectiva de los nitroarenos mediante hidrogenación sin contacto

Hua An^1,2, Yani Ding², Philippe Sautet^3,4

¹Joint School of National University of Singapore and Tianjin University, International Campus of Tianjin University, Binhai New City, Fuzhou 350207, China.

Journal of the American Chemical Society

|October 21, 2024

Resumen

Este estudio introduce una nueva célula H para la hidrogenación selectiva del grupo nitro, previniendo reacciones secundarias no deseadas. La separación espacial de los reactivos garantiza una alta selectividad, superando las limitaciones de los métodos tradicionales.

Área de la Ciencia:

Catálisis
Química orgánica
Ingeniería Química

Sus antecedentes:

La hidrogenación tradicional a menudo sufre de mala selectividad debido a la reducción competitiva de múltiples grupos funcionales en la misma superficie del catalizador.
Los métodos existentes dependen en gran medida de la ingeniería del sitio activo del catalizador para lograr la selectividad, lo que limita la aplicabilidad más amplia.
El mecanismo de Langmuir-Hinshelwood en la hidrogenación en modo de contacto contribuye a las reacciones no selectivas.

Objetivo del estudio:

Desarrollar un método para la hidrogenación altamente selectiva de nitrogrupos, incluso en presencia de otras funcionalidades reducibles.
Para superar el desafío de la hidrogenación competitiva en moléculas complejas.
Demostrar un nuevo enfoque para controlar la selectividad en las reacciones de hidrogenación más allá del diseño del catalizador.

Principales métodos:

Utilizó una célula H imparcial, separando espacialmente el hidrógeno (H2) y los nitroarenos en cámaras distintas conectadas por una membrana de intercambio de protones.
Empleado paladio sobre carbono (Pd/C) para la activación de H2 y nanotubos de carbono (CNT) para la transferencia selectiva de protones/electrones a los grupos nitro.
Investigó una vía única de transferencia de protones/electrones específica para la reducción del grupo nitro a hidroxilamina.

Principales resultados:

Se ha logrado una selectividad del 100% para la reducción del grupo nitro en varios nitroarenos.
Evitó con éxito reacciones secundarias como la hidrogenación de enlaces CC, CO y CC.
Se ha demostrado una selectividad significativamente mayor en comparación con los métodos tradicionales de reactor por lotes que utilizan los mismos catalizadores.

Conclusiones:

El sistema de células H desarrollado elimina efectivamente la hidrogenación competitiva a través de la separación espacial y una vía de transferencia de protones/electrones adaptada.
Este enfoque ofrece un control preciso de la selectividad de hidrogenación, independiente de las modificaciones del sitio activo del catalizador.
Los hallazgos abren nuevas vías para las transformaciones selectivas de grupos funcionales en la síntesis orgánica.

Más Videos Relacionados

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones

Published on: January 21, 2020

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Protocol for the Synthesis of Ortho-trifluoromethoxylated Aniline Derivatives

Published on: January 19, 2016

Videos de Conceptos Relacionados

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...

Reduction of Alkenes: Catalytic Hydrogenation

Reduction of Alkenes: Catalytic Hydrogenation

Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...

Preparation of Amines: Reduction of Oximes and Nitro Compounds

Preparation of Amines: Reduction of Oximes and Nitro Compounds

Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

Electrophilic Aromatic Substitution: Nitration of Benzene

Electrophilic Aromatic Substitution: Nitration of Benzene

The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.

Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...