Video Experimental Relacionado
Updated: Apr 10, 2026
19:58
Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
10.4K
Mecanismos dependientes de haluros para la eliminación reductiva del oro (III)
Matthew S Winston1, William J Wolf1, F Dean Toste1
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
Journal of the American Chemical Society
|June 13, 2015
Resumen
Los investigadores sintetizaron nuevos complejos de haluros organometálicos. La identidad del ligando halogenado influye dramáticamente en la reactividad y la selectividad en la eliminación reductora, siendo la fuerza del enlace Au(III) -X el determinante clave.
Área de la Ciencia:
- Química organometálica Química orgánica de los metales.
- Química Inorgánica La Química Inorgánica es la química inorgánica.
- Mecanismos de reacción Mecanismos de reacción
Sus antecedentes:
- Los complejos organometálicos con centros de oro (III) son de interés para aplicaciones catalíticas.
- La eliminación reductiva es un paso clave en muchos ciclos catalíticos que involucran complejos organometálicos.
- La comprensión de los factores que controlan la selectividad de eliminación reductiva es crucial para el diseño de catalizadores eficientes.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos complejos de haluros organometálicos de oro (III).
- Investigar las vías mecanicistas de eliminación reductiva para los enlaces C(arilo) -X y C(arilo) -CF3.
- Para determinar la influencia del ligando halogenado en la reactividad y la selectividad.
Principales métodos:
- Síntesis de complejos de haluros organometálicos apoyados en oro con fosfina.
- Estudios de termólisis a 122 °C para monitorear la cinética de la reacción.
- Análisis cinético para determinar órdenes de reacción e identificar efectos catalíticos.
- Mediciones termodinámicas de las energías de disociación de los enlaces Au(III) -X.
Principales resultados:
- Dos series de complejos, (Ph3P) Au ((4-Me-C6H4) ((CF3) ((X) y (Cy3P) Au ((4-F-C6H4) ((CF3) ((X), fueron sintetizados (X = I, Br, Cl, F).
- Se encontró que la reactividad y la selectividad cinética de la eliminación reductora eran altamente dependientes del ligando halogenado.
- Se observaron cinéticas de orden cero para X = I o F, mientras que la catálisis del producto estuvo implicada para X = Cl o Br.
- La selectividad para la formación de enlaces C(arilo) -CF3 aumentó con X = I < Br < Cl < F.
- Se produjo exclusivamente la eliminación de C (arilo) -I para X = I, y exclusivamente C (arilo) -CF3 para X = F.
- Las energías de disociación del enlace Au (III) -X aumentaron en el orden X = I < Br < Cl.
Conclusiones:
- La fuerza de los enlaces Au(III) -X del estado fundamental dicta la selectividad de la eliminación reductora de C(arilo) -X y C(arilo) -CF3.
- El ligando halogenado juega un papel crítico en el control de la vía de reacción y la distribución del producto.
- Estos hallazgos proporcionan información fundamental sobre los mecanismos de eliminación reductiva de los complejos de oro.
Más Videos Relacionados
10:42Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of ChalcogenidoplumbatesII or IV
Published on: December 29, 2016
11.3K
10:52Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
3.5K
Videos de Conceptos Relacionados
02:25Elimination Reactions
19.2K
A nucleophile can react with an alkyl halide to give the substitution product by displacing the halogen. Or it can function as a base to give the elimination product by deprotonation of the neighboring carbon to form an alkene. In an elimination reaction, the substrate loses two groups from adjacent carbons forming at least one π bond. The carbon attached to the halogen is called the α carbon, while the adjacent carbon is called the β carbon; hence, these reactions are called...
19.2K
02:46E1 Reaction: Kinetics and Mechanism
18.8K
Here, in contrast to the E2 reaction mechanism, we delve into the aspects of the E1 reaction mechanism, which has two steps: rate-limiting loss of the leaving group and abstraction of the beta hydrogen by a weak base. Typically, the experimental proof for the E1 mechanism is via kinetic studies or isotope studies. While the former demonstrates the first-order kinetics—the dependence of the reaction solely on substrate concentration—the latter proves the abstraction of hydrogen only...
18.8K
01:14Acid Halides to Ketones: Gilman Reagent
4.4K
Lithium dialkyl cuprate, also known as Gilman reagents, selectively reduces acid halides to ketones. The acid chloride is treated with Gilman reagent at −78 °C in the presence of ether solution to produce a ketone in good yield.
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen...
As shown below, the mechanism proceeds in two steps. First, one of the alkyl groups of the reagent acts as a nucleophile and attacks the acyl carbon of the acid chloride to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen...
4.4K
01:19Acid Halides to Alcohols: LiAlH4 Reduction
4.4K
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
4.4K
02:45E2 Reaction: Kinetics and Mechanism
13.6K
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
13.6K
02:52Predicting Products: Substitution vs. Elimination
15.2K
When a nucleophile and an alkyl halide react, nucleophilic substitution and β-elimination reactions compete to generate products.
The following factors can influence the mechanisms competing against each other:
The following factors can influence the mechanisms competing against each other:
15.2K