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Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
El trialquildisileno sustituido por ántrila muestra una distinta transición intramolecular de transferencia de carga
Takeaki Iwamoto1, Maiko Kobayashi, Kei Uchiyama
1Research and Analytical Center for Giant Molecules, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan. iwamoto@mail.tains.tohoku.ac.jp
Journal of the American Chemical Society
|February 20, 2009
Resumen
Los investigadores sintetizaron nuevos disilenos estables con grupos aromáticos policíclicos, revelando interacciones únicas de transferencia de carga intramolecular. El disileno sustituido por ántrilo exhibió una banda de absorción distinta que indicaba la transferencia de carga del disileno al sistema aromático.
Área de la Ciencia:
- Química del organosilicio y su química.
- La fotoquímica es la fotoquímica.
- Química supramolecular de las moléculas.
Sus antecedentes:
- Los disilenos son análogos de silicio de los alquenos, cruciales en la química del organosilicio.
- Los hidrocarburos aromáticos policíclicos (HAP) poseen propiedades electrónicas únicas.
- Comprender las interacciones de transferencia de carga es clave para diseñar nuevos materiales funcionales.
Objetivo del estudio:
- Para sintetizar y caracterizar nuevos disilenos que contienen sustituyentes aromáticos policíclicos.
- Para investigar las interacciones de transferencia de carga intramolecular (ICT) entre el disileno y los sistemas pi aromáticos.
- Para explorar las propiedades fotofísicas que surgen de estas interacciones.
Principales métodos:
- Síntesis de trialquildisilenos sustituidos por 1-naftil, 9-fenantril y 9-antril.
- Análisis espectroscópico (UV-Vis, RMN) para confirmar estructuras y propiedades electrónicas.
- Estudios computacionales para aclarar las estructuras electrónicas y las vías de transferencia de carga.
Principales resultados:
- Síntesis exitosa de los primeros disilenos estables con sustituyentes aromáticos policíclicos únicos.
- Observación de una transferencia de carga intramolecular sin precedentes entre los sistemas de pi disileno y pi aromático.
- El disileno sustituido por ántrila mostraba una banda de absorción TIC distinta debido a la transferencia de carga del donante de pi disileno al aceptador de pi aromático.
Conclusiones:
- Los disilenos sintetizados sirven como una nueva plataforma para estudiar las interacciones pi-pi.
- La transferencia de carga intramolecular es un factor significativo que influye en las propiedades electrónicas y ópticas de estos compuestos.
- Estos hallazgos abren caminos para diseñar nuevos materiales basados en silicio con funcionalidades optoelectrónicas personalizadas.
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01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
02:37Disubstituted Cyclohexanes: cis-trans Isomerism
Depending upon the different spatial orientation of the substituents, the disubstituted cycloalkanes exhibit two types of stereoisomers. The cis isomers have the substituents on the same side of the ring, whereas the trans isomers have the substituents on the opposite sides. These stereoisomers exhibit different physical properties and cannot be interconverted without breaking the carbon-carbon bonds.
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
In cyclohexane, the substituents can occupy different positions generating distinct isomers.
01:29Diels–Alder Reaction: Characteristics of Dienes
The Diels–Alder reaction brings together a diene and a dienophile to form a six-membered ring. Both components have unique characteristics that influence the rate of the reaction.
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
Characteristics of the diene
Conformation
The simplest example of a diene is 1,3-butadiene, an acyclic conjugated π system. At room temperature, the molecule exists as a mixture of s-cis and s-trans conformers by virtue of rotation around the carbon–carbon single bond. Although the s-trans isomer is more stable, the...
02:38Electrophilic Addition to Alkynes: Halogenation
Introduction
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
Halogenation is another class of electrophilic addition reactions where a halogen molecule gets added across a π bond. In alkynes, the presence of two π bonds allows for the addition of two equivalents of halogens (bromine or chlorine). The addition of the first halogen molecule forms a trans-dihaloalkene as the major product and the cis isomer as the minor product. Subsequent addition of the second equivalent yields the tetrahalide.
02:10Reduction of Alkynes to trans-Alkenes: Sodium in Liquid Ammonia
Alkynes can be reduced to trans-alkenes using sodium or lithium in liquid ammonia. The reaction, known as dissolving metal reduction, proceeds with an anti addition of hydrogen across the carbon–carbon triple bond to form the trans product. Since ammonia exists as a gas (bp = −33°C) at room temperature, the reaction is carried out at low temperatures using a mixture of dry ice (sublimes at −78°C) and acetone.
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
When dissolved in liquid ammonia, an alkali metal, such as sodium, dissociates into a...
01:28Diels–Alder Reaction Forming Cyclic Products: Stereochemistry
The Diels–Alder reaction is one of the robust methods for synthesizing unsaturated six-membered rings. The reaction involves a concerted cyclic movement of six π electrons: four π electrons from the diene and two π electrons from the dienophile.