Video Experimental Relacionado

Updated: May 22, 2026

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry

Published on: April 8, 2020

Configuración absoluta para 1,n-glicoles: un enfoque no empírico para la determinación estereoquímica de largo

Xiaoyong Li¹, Carmin E Burrell, Richard J Staples

¹Department of Chemistry, Michigan State University, East Lansing, 48824, United States.

Journal of the American Chemical Society

|May 1, 2012

Resumen

Las configuraciones quirales de 1,n-glicol se determinaron utilizando dicroísmo circular acoplado a excitones (ECCD) y un sistema especial de pinza de porfirina. Este método evita la modificación química para una asignación rápida y precisa de la configuración absoluta.

Área de la Ciencia:

Química orgánica es la química orgánica.
La espectroscopia es una técnica de espectroscopia.
La estereoquímica es la estereoquímica.

Sus antecedentes:

Determinar la configuración absoluta de las moléculas quirales es crucial en la química y el desarrollo de fármacos.
Los métodos tradicionales a menudo requieren la derivación química, que puede llevar mucho tiempo e introducir artefactos.

Objetivo del estudio:

Desarrollar un método rápido y no derivatizado para determinar las configuraciones absolutas de 1,n-glicol.
Para utilizar el dicroísmo circular acoplado a excitones (ECCD) con un nuevo sistema supramolecular.

Principales métodos:

Empleado con un sistema de pinza de porfirinas tris (pentafluorofenil) (TPFP porfirinas).
Espectroscopia aplicada de dicroísmo circular acoplado a excitones (ECCD).
Se analizaron 1,n-glicol (n = 2-12, 16) con dos centros quirales.

Principales resultados:

Determinó con éxito las configuraciones absolutas de varios 1,n-glicol.
Demostró la eficacia del sistema de pinza de porfirina TPFP en el análisis de ECCD.
Propuso un modo de complejación "lateral" entre la pinza de porfirina y el huésped diol.

Conclusiones:

El método ECCD basado en la pinza de porfirina TPFP proporciona una forma rápida y eficiente de asignar configuraciones absolutas de diolos.
Este enfoque no derivatizado simplifica el análisis estereoquímico y es ampliamente aplicable.
Los hallazgos ofrecen una nueva herramienta para el reconocimiento y análisis quiral en química orgánica.

Más Videos Relacionados

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D ¹H NMR

Published on: December 16, 2013

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

Hierarchical and Programmable One-Pot Oligosaccharide Synthesis

Published on: September 6, 2019

Videos de Conceptos Relacionados

Stereoisomerism of Cyclic Compounds

Stereoisomerism of Cyclic Compounds

In this lesson, we delve into the role of ring conformation and its stability, which determines the spatial arrangement and, consequently, the molecular symmetry and stereoisomerism of cyclic compounds. 1,2-Dimethylcyclohexane is used as a case study to evaluate the possible number of stereoisomers. Here, given the multiple (n = 2) chiral centers, there are 2n = 4 possible configurations that lack a plane of symmetry, as the ring skeleton exists in a non-planar chair conformation. In addition,...

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

¹H NMR of Conformationally Flexible Molecules: Temporal Resolution

At room temperature, the chair conformer of cyclohexane undergoes rapid ring flipping between two equivalent chair conformers at a rate of approximately 105 times per second. These two chair conformers are in equilibrium. The rapid ring flipping results in the interconversion of the axial proton to an equatorial proton and an equatorial to the axial proton. Such interconversions are too rapid and cannot be detected on the NMR timescale. Hence, the NMR spectrometer cannot distinguish between the...

¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons

¹H NMR Chemical Shift Equivalence: Enantiotopic and Diastereotopic Protons

Replacing each alpha-hydrogen in chloroethane by bromine (or a different functional group) yields a pair of enantiomers. Such protons are called prochiral or enantiotopic and are related by a mirror plane. Enantiotopic protons are chemically equivalent in an achiral environment. Because most proton NMR spectra are recorded using achiral solvents, enantiotopic hydrogens yield a single signal.
In chiral compounds such as 2-butanol, replacing the methylene hydrogens at C3 produces a pair of...

¹H NMR: Long-Range Coupling

¹H NMR: Long-Range Coupling

The coupling interactions of nuclei across four or more bonds are usually weak, with J values less than 1 Hz. While these are usually not observed in spectra, the presence of multiple bonds along the coupling pathway can result in observable long-range coupling.
In alkenes, spin information is communicated via σ–π overlap, as seen in allylic (four-bond) and homoallylic (five-bond) couplings. These coupling interactions are stronger when the σ bond is parallel to the alkene π orbitals.

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration

The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.

Naming Enantiomers

Naming Enantiomers

The naming of enantiomers employs the Cahn–Ingold–Prelog rules that involve assigning priorities to different substituent groups at a chiral center. Each enantiomer, being a distinct molecule, is assigned a unique name by the Cahn–Ingold–Prelog (CIP) rules, also called the R–S system. The prefix R- or S- attached to the chiral centers in an enantiomer is dependent on the spatial arrangement of the four substituents on the chiral center. The R–S system essentially comprises three steps:...