Video Experimental Relacionado
Updated: Jan 26, 2026
08:37
Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
3.2K
Reorganización dinámica y confinamiento de los sitios activos de TiIV Controla la catálisis de la epoxidación de las
Nicolás A Grosso-Giordano1, Adam S Hoffman2, Alexey Boubnov2
1Department of Chemical and Biomolecular Engineering , University of California, Berkeley , Berkeley , California 94720 , United States.
Journal of the American Chemical Society
|April 9, 2019
Resumen
El confinamiento de los sitios catalíticos de titanio dentro de las bolsas de silicato mejora significativamente las tasas de epoxidación de olefinas al reducir las barreras entrópicas. La reorganización dinámica favorece estos sitios confinados, ofreciendo nuevas vías para el control de la reactividad superficial.
Área de la Ciencia:
- Catálisis heterogénea
- Química de las superficies
- Ciencias de los materiales
Sus antecedentes:
- La epoxidación de las olefinas es un proceso industrial crucial.
- El control de los entornos activos del sitio influye en el rendimiento catalítico.
- Los materiales de silicato de titanio ofrecen propiedades catalíticas ajustables.
Objetivo del estudio:
- Investigar el impacto del confinamiento dinámico en los centros catalíticos aislados de titanio para la epoxidación de olefinas.
- Aclarar el papel de la localización y la reorganización del sitio activo en la actividad catalítica.
- Explorar el potencial de las bolsas superficiales poco profundas para mejorar la reactividad.
Principales métodos:
- La síntesis de titanio (IV) se centra en silicatos con confinamiento controlado (sin confinamiento frente a bolsas de 12-MR).
- Estudios cinéticos de la epoxidación del ciclohexeno con el hidroperoxido de tert-butilo.
- Cálculos de la teoría funcional de la densidad (DFT) para el análisis de la estructura electrónica.
- Análisis termodinámico de los parámetros de activación (entalpia y entropía).
Principales resultados:
- Los sitios confinados de Ti (IV) dentro de bolsas de 12 MR mostraron un aumento de la tasa de epoxidación de aproximadamente 5 veces en comparación con los sitios no confinados.
- La reorganización dinámica condujo a la ocupación preferente de sitios activos confinados.
- El confinamiento redujo las barreras entrópicas, facilitando la asociación de reactivos y la formación de estados de transición.
- La entalpía de activación se mantuvo constante, mientras que los cambios de entropía explicaron las diferencias de velocidad.
Conclusiones:
- El confinamiento parcial en bolsillos superficiales aumenta la reactividad catalítica a través de efectos entrópicos.
- La reorganización dinámica juega un papel clave en la dirección de sitios activos a entornos confinados favorables.
- Este enfoque ofrece una nueva estrategia para controlar la reactividad superficial, particularmente para moléculas voluminosas.
Videos de Conceptos Relacionados
02:50Catalysis
30.2K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
30.2K
03:00Preparation of Epoxides
9.2K
Overview
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
Epoxides result from alkene oxidation, which can be achieved by a) air, b) peroxy acids, c) hypochlorous acids, and d) halohydrin cyclization.
Epoxidation with Peroxy Acids
Epoxidation of alkenes via oxidation with peroxy acids involves the conversion of a carbon–carbon double bond to an epoxide using the oxidizing agent meta-chloroperoxybenzoic acid, commonly known as MCPBA. Since the O–O bond of peroxy acids is very weak, the addition of electrophilic oxygen of peroxy acids to...
9.2K
02:57Sharpless Epoxidation
5.1K
The conversion of allylic alcohols into epoxides using the chiral catalyst was discovered by K. Barry Sharpless and is known as Sharpless epoxidation. The use of a chiral catalyst enables the formation of one enantiomer of the product in excess. This chiral catalyst is mainly a chiral complex of titanium tetraisopropoxide and tartrate ester (specific stereoisomer). The stereoisomer used in the chiral catalyst dictates the formation of the enantiomer of the product. In other words, the use of...
5.1K
02:40Ligand Binding Sites
14.9K
Proteins are dynamic macromolecules that carry out a wide variety of essential processes; however, the activities of most proteins depend on their interactions with other molecules or ions, known as ligands.
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...
14.9K
01:49Conserved Binding Sites
5.1K
Many proteins’ biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein known as ligand-binding sites. Ligand-binding sites are often conserved among homologous proteins as these sites are critical for protein function.
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally...
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally...
5.1K
02:38Structure and Nomenclature of Epoxides
7.9K
Cyclic ethers are heterocyclic compounds with an oxygen atom in the ring along with carbon atoms. They are named depending on the number of carbon atoms present in their ring system. Cyclic ethers with a three-membered ring system are called “oxirane”, four-membered ring systems as “oxetane”, five-membered ring systems as “oxolane”, and six-membered ring systems as “oxane”. The cyclic structure of these rings imposes angle strain, and this strain...
7.9K