Video Experimental Relacionado

Updated: Jun 2, 2026

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

Hidrogenación catalizada por iridio de compuestos N-heterocíclicos bajo condiciones suaves por una vía de la esfera

Graham E Dobereiner¹, Ainara Nova, Nathan D Schley

¹Department of Chemistry, Yale University, 225 Prospect Street, P.O. Box 208107, New Haven, Connecticut 06520, USA.

Journal of the American Chemical Society

|April 23, 2011

Resumen

Un nuevo catalizador de iridio permite la hidrogenación de las quinolinas en condiciones suaves (25 °C, 1 atm H2). Este estudio revela un inusual mecanismo de la esfera exterior para esta importante transformación química.

Área de la Ciencia:

Química organometálica Química orgánica de los metales.
La catálisis de la catálisis.
Síntesis orgánica La síntesis orgánica.

Sus antecedentes:

Las quinolinas son importantes compuestos heterocíclicos con amplias aplicaciones.
Los métodos catalíticos eficientes para la reducción de la quinolina son cruciales en la síntesis orgánica.
El desarrollo de catalizadores de hidrogenación más suaves y efectivos sigue siendo un desafío clave.

Objetivo del estudio:

Desarrollar un nuevo catalizador de iridio homogéneo para la hidrogenación de la quinolina.
Para investigar el mecanismo de reacción en condiciones suaves.
Explorar el alcance y las limitaciones del sistema catalítico.

Principales métodos:

Síntesis y caracterización del iridio (I) precursores del catalizador NHC.
Hidrogenación catalítica de varios derivados de la quinolina.
Estudios experimentales que incluyen el aislamiento y la caracterización de los intermedios de reacción.
Cálculos de la Teoría Funcional de Densidad (DFT) para aclarar el mecanismo de reacción.

Principales resultados:

Se desarrolló un catalizador de iridio homogéneo altamente activo y estable.
El catalizador hidrogena eficazmente una amplia gama de quinolinas funcionalizadas a 25 °C y 1 atm H2.
Se propuso y respaldó con datos experimentales y teóricos un inusual mecanismo escalonado de la esfera externa que involucra la transferencia secuencial de protones e hidruro.
Se caracterizaron los principales intermedios, incluidos los hidratos de iridio (III) y un complejo catiónico de dihidrógeno dihidruro de iridio (III) dihidrógeno.

Conclusiones:

El catalizador de iridio desarrollado ofrece una ruta eficiente y suave para la hidrogenación de la quinolina.
El esclarecido mecanismo de la esfera externa proporciona información fundamental sobre los procesos de hidrogenación catalítica.
Comprender el mecanismo explica el alcance del sustrato y las variaciones de la actividad del catalizador, guiando el diseño futuro del catalizador.

Más Videos Relacionados

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

A Microwave-Assisted Direct Heteroarylation of Ketones Using Transition Metal Catalysis

Published on: February 16, 2020

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions

Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions

Published on: March 20, 2014

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 surface of...

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.

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...

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride

Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride

Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...

Heterogeneous Catalysis

Heterogeneous Catalysis

Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...