Video Experimental Relacionado
Updated: May 13, 2026
10:44
Isolating Free Carbenes, their Mixed Dimers and Organic Radicals
Published on: April 19, 2019
3-Trimetilsilcilciclobutilideno. también conocido como 3-trimetilsilcilciclobutilideno. El efecto γ del silicio sobre
1Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, USA. creary.1@nd.edu
Journal of the American Chemical Society
|March 27, 2013
Resumen
El 3-trimetilsiliciclobutilideno se reorganiza a 1-trimetilsiliciclobutano a través de la migración de 1,3-hidrógeno, no de la migración silílica. El análisis computacional revela una conformación de carbeno estable que favorece esta vía.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- Química computacional es la química computacional.
Sus antecedentes:
- La química de los carbenos es crucial para la síntesis orgánica.
- La comprensión de los mecanismos de reordenamiento de carbenos proporciona información sobre las vías de reacción.
Objetivo del estudio:
- Para investigar el mecanismo de reordenamiento del 3-trimetilsilcilciclobutilideno.
- Para aclarar los factores que influyen en la reactividad del carbeno y la distribución del producto.
Principales métodos:
- Pirólisis de una sal de sodio de tosilhidrazona para generar el carbeno.
- Estudios de etiquetado para hacer un seguimiento de la migración atómica.
- Estudios computacionales (DFT) para analizar las conformaciones de carbenos y los estados de transición.
Principales resultados:
- El producto principal de la pirólisis de carbenos es el 1-trimetilsililbiciclobutano.
- Los estudios de etiquetado confirmaron la migración de 1,3-hidrógeno como la vía dominante.
- El análisis computacional identificó una conformación de carbeno de baja energía estabilizada por la interacción con el enlace C-Si, lo que dificulta la migración silílica.
Conclusiones:
- El reordenamiento observado es impulsado principalmente por la migración de 1,3-hidrógeno debido a factores estéricos y electrónicos en la conformación preferida del carbeno.
- La generación fotoquímica en el metanol conduce a un intermediario de carbocatión, mientras que la reacción en la dimetilamina implica un ataque nucleofílico en el centro de carbenos.
Videos de Conceptos Relacionados
01:07Radicals: Electronic Structure and Geometry
This lesson delves into the geometry of a radical, which is influenced by the electronic structure of the molecule. The principle is similar to that of a lone pair, where the unpaired electron influences the geometry at the radical center.
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...
02:26Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
01:28Stability of Conjugated Dienes
Introduction
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
A comparison of the enthalpies of hydrogenation of dienes reveals that conjugated dienes release less heat on hydrogenation, rendering them more stable than their nonconjugated analogs.
02:46Halogenation of Alkenes
Halogenation is the addition of chlorine or bromine across the double bond in an alkene to yield a vicinal dihalide. The reaction occurs in the presence of inert and non-nucleophilic solvents, such as methylene chloride, chloroform, or carbon tetrachloride.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
Consider the bromination of cyclopentene. Molecular bromine is polarized in the proximity of the π electrons of cyclopentene. An electrophilic bromine atom adds across the double bond, forming a cyclic bromonium ion intermediate.
02:30Stability of Substituted Cyclohexanes
This lesson discusses the stability of substituted cyclohexanes with a focus on energies of various conformers and the effect of 1,3-diaxial interactions.
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
The two chair conformations of cyclohexanes undergo rapid interconversion at room temperature. Both forms have identical energies and stabilities, each comprising equal amounts of the equilibrium mixture. Replacing a hydrogen atom with a functional group makes the two conformations energetically non-equivalent.
For example, in...
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.