Video Experimental Relacionado
Updated: Jan 24, 2026
06:46
Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
7.9K
Adiciones fotociclointermoleculares de 2 + 2 carbonilo-olefinas habilitadas por el Cu (I) -norborneno MLCT
Daniel M Flores1, Valerie A Schmidt1
1Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093 , United States.
Journal of the American Chemical Society
|May 24, 2019
Resumen
Los investigadores desarrollaron un nuevo precatalizador de cobre para reacciones de fotocicloadición. Este método permite la síntesis de oxetanos a partir de alquilcetonas, superando las limitaciones de las reacciones tradicionales de Paternò-Büchi.
Área de la Ciencia:
- Química orgánica
- La fotoquímica
- Catálisis
Sus antecedentes:
- La reacción de Paternò-Büchi es un método común para sintetizar oxetanos a través de la fotocicloadición.
- Los métodos tradicionales se enfrentan a limitaciones debido a las limitaciones mecánicas de la excitación de carbonilo y la intercepción de olefinas, particularmente con sustratos difíciles como las alquilcetonas.
Objetivo del estudio:
- Desarrollar un nuevo sistema catalítico para la fotocicloadición intermolecular de 2 + 2 carbonilo-olefinas.
- Para permitir el uso de cetonas alquilo en la formación de oxetano, ampliando el alcance de esta reacción.
Principales métodos:
- Se utilizó un precatalizador de cobre para activar selectivamente las olefinas a través de la coordinación del metal.
- Se investigó el mecanismo de reacción mediante estudios mecanicistas.
- Caracterizó el estado intermedio de descanso Cu-norbornene.
Principales resultados:
- Se ha logrado una fotocicloadición intermolecular selectiva de 2 + 2 carbonilo-olefinas.
- Utilizó con éxito cetonas alquilo desafiantes como sustratos.
- Se identificó un proceso de transferencia de carga metal-ligando (MLCT) que involucra un intermediario Cu-norborneno que conduce a la formación de oxetano.
Conclusiones:
- El sistema de precatalizador Cu ((I) desarrollado supera eficazmente las limitaciones de las vías de irradiación directa para la síntesis de oxetano.
- Este enfoque catalítico amplía la utilidad de las reacciones de fotocicloadición para la construcción de motivos de oxetano, especialmente a partir de compuestos de carbonilo menos reactivos.
Videos de Conceptos Relacionados
02:28Intermolecular Forces in Solutions
38.9K
The formation of a solution is an example of a spontaneous process, a process that occurs under specified conditions without energy from some external source.
When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no different than those present in the separated components, the solution is formed with no accompanying energy change. Such a solution is called an ideal solution. A mixture of ideal gases (or gases such as helium and argon,...
When the strengths of the intermolecular forces of attraction between solute and solvent species in a solution are no different than those present in the separated components, the solution is formed with no accompanying energy change. Such a solution is called an ideal solution. A mixture of ideal gases (or gases such as helium and argon,...
38.9K
03:13Intermolecular Forces
70.6K
Atoms and molecules interact through bonds (or forces): intramolecular and intermolecular. The forces are electrostatic as they arise from interactions (attractive or repulsive) between charged species (permanent, partial, or temporary charges) and exist with varying strengths between ions, polar, nonpolar, and neutral molecules. The different types of intermolecular forces are ion–dipole, dipole–dipole, hydrogen bonds, and dispersion; among these, dipole–dipole, hydrogen...
70.6K
01:13meta-Directing Deactivators: –NO2, –CN, –CHO, –CO2R, –COR, –CO2H
6.6K
All meta-directing substituents are deactivating groups. These substituents withdraw electrons from the aromatic ring, making the ring less reactive toward electrophilic substitution. For example, the nitration of nitrobenzene is 100,000 times slower than that of benzene because of the deactivating effect of the nitro group. The first step in an electrophilic aromatic substitution is the addition of an electrophile to form a resonance-stabilized carbocation. The energy diagrams for...
6.6K
03:00Intermolecular vs Intramolecular Forces
96.4K
Intermolecular forces (IMF) are electrostatic attractions arising from charge-charge interactions between molecules. The strength of the intermolecular force is influenced by the distance of separation between molecules. The forces significantly affect the interactions in solids and liquids, where the molecules are close together. In gases, IMFs become important only under high-pressure conditions (due to the proximity of gas molecules). Intermolecular forces dictate the physical properties of...
96.4K
01:202° Amines to N-Nitrosamines: Reaction with NaNO2
5.4K
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
5.4K
02:14SN2 Reaction: Kinetics
10.2K
Kinetic Studies and Significance
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
In a chemical reaction, a relationship exists between the concentration of reactants and the rate at which the reaction proceeds. The study to measure this relationship is known as the kinetics of a chemical reaction. Kinetic studies are used to deduce the rate law of a chemical reaction, which provides information about the species involved during the transition state of the rate-determining step. Thus, kinetic studies help to derive the mechanism of a...
10.2K