Video Experimental Relacionado
Updated: Jul 16, 2026
06:00
One-pot Microwave-assisted Conversion of Anomeric Nitrate-esters to Trichloroacetimidates
Published on: January 15, 2018
Fijación rápida del cloruro de metileno por una amina macrocíclica
Jung-Jae Lee1, Keith J Stanger, Bruce C Noll
1Department of Chemistry and Biochemistry and Walther Cancer Research Center, University of Notre Dame, Notre Dame, Indiana 46556, USA.
Journal of the American Chemical Society
|March 24, 2005
Resumen
Las aminas macrocíclicas reaccionan rápidamente con el cloruro de metileno, formando sales cuaternarias de amonio. Esta alquilación es miles de veces más rápida que con las aminas acíclicas, debido a un mecanismo complejo activado específico.
Área de la Ciencia:
- Química orgánica es la química orgánica.
- La cinética química es la cinética química.
Sus antecedentes:
- Las aminas macrocíclicas ofrecen una reactividad única debido a su estructura.
- Comprender la cinética de la reacción es crucial para la química sintética.
Objetivo del estudio:
- Para investigar la cinética de alquilación de una amina macrocíclica con cloruro de metileno.
- Para dilucidar el mecanismo de reacción y compararlo con análogos acíclicos.
Principales métodos:
- Estudios cinéticos que miden las velocidades de reacción a 25.0°C.
- Cristalografía de rayos X para determinar las estructuras de los reactivos y productos.
- Análisis computacional para apoyar los mecanismos propuestos.
Principales resultados:
- La reacción procede a través de cinética de pseudo-primer orden con una vida media de 2,0 min.
- La alquilación de aminas macrocíclicas es ~50.000 veces más rápida que las aminas acíclicas.
- El producto es un par de iones estrechamente asociados, no iones completamente separados.
Conclusiones:
- Se prefiere un mecanismo que implique un complejo de pre-reacción activado.
- La estructura macrocíclica mejora significativamente la tasa de alquilación de SN2.
- Los datos estructurales y cinéticos apoyan el mecanismo de formación de pares de iones propuesto.
Videos de Conceptos Relacionados
01:12Carbon Skeletons
Life on Earth is carbon-based, as all macromolecules that make up living organisms contain carbon atoms. All organic compounds have a carbon backbone. Each carbon atom is tetravalent and can bond with four other atoms, making it an extraordinarily flexible component of biological molecules. Because carbon’s valence electrons are stable, it rarely becomes an ion. As the carbon chain increases in length, structural modifications such as ring structures, double bonds, and branching side chains...
03:02Organic Compounds
All living things are formed mostly of carbon compounds called organic compounds. The category of organic compounds includes both natural and synthetic compounds that contain carbon. Although a single, precise definition has yet to be identified by the chemistry community, most agree that a defining trait of organic molecules is the presence of carbon as the principal element, bonded to hydrogen and other carbon atoms. However, some carbon-containing compounds such as carbonates, cyanides, and...
02:45Functional Groups
Functional groups are a group of atoms with characteristic properties, which when linked to the carbon skeleton of a molecule, alter the properties of that molecule. For example, the presence of certain functional groups on a molecule will make them hydrophilic, whereas others will make them hydrophobic. These functional groups are an indispensable part of organic chemistry and important components of biological molecules, such as carbohydrates, proteins, lipids, and nucleic acids. Each...
01:19Aldehydes and Ketones with Alcohols: Hemiacetal Formation
Similar to water, alcohols can add to the carbonyl carbon of the aldehydes and ketones. The addition of one molecule of alcohol to the carbonyl compound forms the hemiacetal or half acetal. As depicted below, in a hemiacetal, the carbon is directly linked to an OH and OR group.
01:28Structures of Carboxylic Acid Derivatives
Structure of Carboxylic Acid Derivatives
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
Carboxylic acid derivatives contain an acyl group attached to a heteroatom such as chlorine, oxygen, or nitrogen. The carbonyl carbon and oxygen are both sp2-hybridized with an unhybridized p orbital.
The three sp2 orbitals of the carbonyl carbon form three σ bonds, one each with the carbonyl oxygen, the α carbon, and the heteroatom, whereas the other two sp2 orbitals of the carbonyl oxygen are occupied by the lone pairs. Further, the unhybridized p...
01:28Carbon-dioxide Fixation
Carbon dioxide fixation in prokaryotes enables the assimilation of inorganic carbon into organic molecules, supporting biosynthetic pathways, sustaining ecosystems, and contributing to the global carbon cycle. It also has industrial applications in carbon capture and bioproduct synthesis. Autotrophic organisms rely on this process to utilize CO₂ as a carbon source in diverse environments.The Calvin CycleThe Calvin cycle is the most widespread carbon fixation mechanism, primarily used by...