Video Experimental Relacionado
Updated: Mar 21, 2026
09:08
A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes
Published on: February 27, 2017
11.2K
Introducción de la metátesis "Ynene": la polimerización de la metátesis de expansión de anillo conduce a polímeros
Soufiane S Nadif1, Tomohiro Kubo2, Stella A Gonsales1
1Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
Journal of the American Chemical Society
|May 13, 2016
Resumen
Las alquilidinas de tungsteno inician la polimerización del norborneno, dando lugar al polinorborneno cíclico. El complejo 3 produce polímeros cíclicos altamente cis y sindiotácticos, confirmados por técnicas avanzadas de caracterización.
Área de la Ciencia:
- Química organometálica
- Ciencia de los Polímeros
- Catálisis
Sus antecedentes:
- Las alquilidinas de tungsteno son precursores versátiles en la química organometálica.
- La metástasis y la polimerización de las olefinas son transformaciones clave en la catálisis.
- El control de la topología del polímero y la estereoquímica es crucial para las propiedades del material.
Objetivo del estudio:
- Para investigar la reactividad de las alquilidinas de tungsteno con el etileno.
- Explorar la actividad catalítica de estos complejos en la polimerización del norborneno.
- Caracterizar las estructuras de polinorborenos resultantes, centrándose en la topología cíclica y la estereoselectividad.
Principales métodos:
- Síntesis y caracterización de las alquilidinas de tungsteno.
- Reacciones con etileno para formar metaciclobuteno y complejos de alquilideno atados.
- Polimerización por norborneno utilizando alquilinas de tungsteno como iniciadores.
- Análisis de las propiedades del polímero, incluida la viscosidad intrínseca, el radio de rotación y el tiempo de elución.
Principales resultados:
- Las alquilidinas de tungsteno (1 y 3) reaccionan con el etileno, formando metaciclobuteno (2) y un alquilideno atado (4).
- Ambos complejos inician la polimerización del norborneno a temperatura ambiente.
- El complejo 1 produce polímeros no estereoselectivos, mientras que el complejo 3 produce polinorborenos cíclicos altamente cis y sindiotácticos.
- Los datos de caracterización confirman la topología cíclica del polinorborneno sintetizado.
Conclusiones:
- Las alquilidinas de tungsteno sirven como iniciadores efectivos para la polimerización del norborneno.
- El entorno del ligando influye significativamente en la estereoselectividad y la topología del polinorborneo resultante.
- El complejo 3 proporciona una vía para el polinorboreno cíclico altamente ordenado con aplicaciones potenciales en materiales avanzados.
Más Videos Relacionados
Videos de Conceptos Relacionados
01:13Olefin Metathesis Polymerization: Overview
2.7K
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
2.7K
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
3.3K
Ring-opening metathesis polymerization or ROMP involves strained cycloalkenes as starting materials. The mechanism of ROMP proceeds by reacting cycloalkene with Grubbs catalyst to give metallacyclobutane intermediate which undergoes a ring-opening reaction to form new carbene. The new carbene reacts with another molecule of cycloalkene. Repetition of these steps leads to the formation of an unsaturated open-chain polymer product. All these steps are reversible, however, relieving the ring...
3.3K
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
2.3K
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
2.3K
02:35Free-Radical Chain Reaction and Polymerization of Alkenes
10.2K
The conversion of alkenes to macromolecules called polymers is a reaction of high commercial importance. The structure of the polymer is defined by a repeating unit, while the terminal groups are considered insignificant. The average degree of polymerization represents the number of repeating units in the polymer molecule and is denoted by the subscript n.
10.2K
01:17Radical Chain-Growth Polymerization: Chain Branching
2.6K
The skeletal structure of polymers synthesized via radical polymerization is always branched. For example, the polymerization of ethylene by radical polymerization results in a low-density grade of polyethylene with a heavily branched skeletal structure. Here, the radical site abstracts hydrogen from the growing chain, and the radical site shifts from the end (a primary carbon center) to anywhere within the growing chain (a secondary carbon center). Consequently, the part of the chain from the...
2.6K
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
4.2K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
4.2K