Video Experimental Relacionado

Updated: Mar 15, 2026

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry

Published on: October 18, 2019

Activación y estabilización mediadas por intercambio de ligandos de un catalizador de metátesis de olefinas re-basado

Alessandro Gallo, Anthony Fong, Kai C Szeto¹

¹Laboratoire de Chimie, Catalyse, Polymères et Procédés, UMR 5265 CNRS/ESCPE-Lyon/UCBL, ESCPE Lyon, F-308-43, Boulevard du 11 Novembre 1918, F-69616 Villeurbanne Cedex, France.

Journal of the American Chemical Society

|August 31, 2016

Resumen

La cloración extensiva de alumina (Al2O3) crea sitios ácidos de Lewis muy activos. Esta modificación mejora significativamente el rendimiento del catalizador de metiltrioxorenio (MTO) para la metátesis de olefinas, aumentando la actividad y la estabilidad.

Área de la Ciencia:

Catálisis heterogénea
Química orgánica de los metales
Ciencias de la superficie

Sus antecedentes:

La metátesis de olefinas es una reacción crucial en la síntesis orgánica.
El metiltrioxorenio (MTO) es un catalizador conocido de la metástasis, pero sufre de inestabilidad.
La alumina (γ-Al2O3) es un soporte de catalizador común.

Objetivo del estudio:

Desarrollar un catalizador de metástasis de olefinas heterogéneo más activo y estable.
Investigar el efecto de la cloración superficial en la catálisis MTO.
Para aclarar la interacción entre el MTO y la alúmina clorada.

Principales métodos:

Clorado extensivo de γ-Al2O3
Adsorción de metiltrioxorenio (MTO)
Espectroscopia EXAFS de borde Re LIII
Cálculos de la teoría de la función de densidad (DFT)
Espectroscopia infrarroja (IR) y de RMN en estado sólido

Principales resultados:

La cloración crea sitios ácidos de Lewis en γ-Al2O3, agotando los grupos hidroxilo.
El MTO inmovilizado sufre un intercambio de ligandos con la superficie clorada.
Se forma una nueva especie activa, [CH3ReO2Cl+], que interactúa con el soporte.
El catalizador clorado presenta una actividad y estabilidad significativamente más altas (100 000 TON) en comparación con el MTO/γ-Al2O3 no clorado.

Conclusiones:

La cloración superficial de la alúmina activa efectivamente el MTO para la metátesis de olefinas a baja temperatura.
El catalizador mejorado demuestra una actividad y estabilidad superiores, superando las limitaciones de los catalizadores anteriores basados en Re.
Este catalizador reformulado representa un avance significativo para las aplicaciones industriales de la metátesis de olefinas.

Más Videos Relacionados

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

Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction

Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction

Published on: August 23, 2018

Videos de Conceptos Relacionados

Olefin Metathesis Polymerization: Overview

Olefin Metathesis Polymerization: Overview

Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...

Radical Substitution: Allylic Chlorination

Radical Substitution: Allylic Chlorination

Typically, when alkenes react with halogens at low temperatures, an addition reaction occurs. However, upon increasing the temperature or under reaction conditions that form radicals, providing a low but steady concentration of halogen radicals, allylic substitution reaction is favored. This is because allylic hydrogens are very reactive as the formed intermediate is resonance stabilized. For example, when propene is treated with chlorine in the gas phase at 400 °C, it undergoes allylic...

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 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.

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...

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide

Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.