Jove
Visualize
Contáctanos

Videos de Conceptos Relacionados

Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration02:34

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.
Anionic Chain-Growth Polymerization: Overview01:20

Anionic Chain-Growth Polymerization: Overview

The polymerization process that involves carbanion as an intermediate is called anionic polymerization. It is also a type of addition or chain-growth polymerization. Anionic polymerization gets initiated by a strong nucleophile such as an organolithium or a Grignard reagent. The most commonly used initiator for anionic polymerization is butyl lithium. Monomers involved in anionic polymerization must possess a vinyl group bonded to one or two electron-withdrawing groups. For instance,...
Anionic Chain-Growth Polymerization: Mechanism01:04

Anionic Chain-Growth Polymerization: Mechanism

The mechanism for anionic chain-growth polymerization involves initiation, propagation, and termination steps. In the initiation step, a nucleophilic anion, such as butyl lithium, initiates the polymerization process by attacking the π bond of the vinylic monomer. As a result, a carbanion, stabilized by the electron‐withdrawing group, is generated. The resulting carbanion acts as a Michael donor in the propagation step and attacks the second vinylic monomer, which acts as a Michael acceptor.
Cationic Chain-Growth Polymerization: Mechanism00:57

Cationic Chain-Growth Polymerization: Mechanism

The cationic polymerization mechanism consists of three steps: initiation, propagation, and termination. In the initiation step of the polymerization process, the π bond of a monomer gets protonated by the Lewis acid catalyst, which is formed from boron trifluoride and water. The protonation of the π bond generates a carbocation stabilized by the electron‐donating group. In the propagation step, the π bond of the second monomer acts as a nucleophile and attacks the generated carbocation,...
Olefin Metathesis Polymerization: Overview01:13

Olefin Metathesis Polymerization: Overview

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...
Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)00:53

Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)

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...

También podría leer

Artículos Relacionados

Artículos vinculados a este trabajo por autores compartidos, revista y gráfico de citas.

Ordenar por
Same author

The Effects of Preparation Methods and Internal Electron Donors on Ziegler-Natta Catalyst Performance and Polypropylene Properties.

Polymers·2026
Same author

Recent Advances in Coordination-Insertion Copolymerization of Ethylene with Polar Monomers Catalyzed with Pd and Ni Complexes.

Polymers·2026
Same author

Large Language Models for Accurate Medical Chart Abstraction: Enabling Scalable and Secure AI Deployment in Stroke.

AJNR. American journal of neuroradiology·2026
Same author

Olefin insertion using <i>ansa</i>-zirconocenes and methylaluminoxane (MAO) involves Janus-like, sheet anions.

Chemical communications (Cambridge, England)·2025
Same author

Ceramide test in patients with erectile dysfunction to assess cardiovascular risk.

The journal of sexual medicine·2025
Same author

Abn-BLIP: Abnormality-aligned Bootstrapping Language-Image Pre-training for pulmonary embolism diagnosis and report generation from CTPA.

Medical image analysis·2025
Same journal

A Ni-Mediated Cross-Coupling Approach to Deuterated <sup>18</sup>F- Fluoromethylated (Hetero)arenes.

Journal of the American Chemical Society·2026
Same journal

Efficient Light-Driven CO<sub>2</sub> Capture and Reversible Release Enabled by Metastable Photoacid-Decorated Metal-Organic Frameworks.

Journal of the American Chemical Society·2026
Same journal

In Situ Raman Spectroscopy Reveals the Dynamic Evolution and Ethanol Dependence of SEI Structure in Li-Mediated N<sub>2</sub> Reduction Reaction.

Journal of the American Chemical Society·2026
Same journal

Solvent Esterification and Stoichiometric Control in Ambient-Grown FAPbI<sub>3</sub> Single-Crystal Solar Cells.

Journal of the American Chemical Society·2026
Same journal

Unlocking Azulene Functionalization via Strain-Induced Azulyne Intermediates.

Journal of the American Chemical Society·2026
Same journal

An Oxazine-Locked Covalent Organic Framework by a Tandem Pinner/Schiff Base Reaction for Hydrogen Peroxide Photosynthesis.

Journal of the American Chemical Society·2026
Ver todos los artículos relacionados
JoVE
x logofacebook logolinkedin logoyoutube logo
ACERCA DE JoVE
Visión GeneralLiderazgoBlogCentro de Ayuda JoVE
AUTORES
Proceso de PublicaciónConsejo EditorialAlcance y PolíticasRevisión por ParesPreguntas FrecuentesEnviar
BIBLIOTECARIOS
TestimoniosSuscripcionesAccesoRecursosConsejo Asesor de BibliotecasPreguntas Frecuentes
INVESTIGACIÓN
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchivo
EDUCACIÓN
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualCentro de Recursos para ProfesoresSitio de Profesores
Términos y Condiciones de Uso
Política de Privacidad
Políticas

Video Experimental Relacionado

Updated: Jun 14, 2026

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
07:28

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

Published on: November 27, 2015

Efectos de contrapartida en la polimerización del propileno utilizando complejos de ansa-metaloceno de dos estados.

Muqtar Mohammed1, Marcio Nele, Abdulaziz Al-Humydi

  • 1Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.

Journal of the American Chemical Society
|June 26, 2003
PubMed
Resumen
Este resumen es generado por máquina.

Este estudio investigó la polimerización del propileno utilizando catalizadores de metaloceno y varios co-iniciadores. La microestructura del polímero no se vio afectada en gran medida por la elección de la contraparte, con un comportamiento del catalizador que difiere principalmente en los regímenes operativos en lugar de la estereoselectividad intrínseca.

Más Videos Relacionados

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions
10:53

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions

Published on: October 10, 2016

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes
09:08

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Published on: February 27, 2017

Videos de Experimentos Relacionados

Last Updated: Jun 14, 2026

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization
07:28

Ethylene Polymerizations Using Parallel Pressure Reactors and a Kinetic Analysis of Chain Transfer Polymerization

Published on: November 27, 2015

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by &#960;-&#960; Stacking Interactions
10:53

Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions

Published on: October 10, 2016

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes
09:08

A Simple and Efficient Protocol for the Catalytic Insertion Polymerization of Functional Norbornenes

Published on: February 27, 2017

Área de la Ciencia:

  • Química de Polímeros La Química de Polímeros es la química de los polímeros.
  • Química organometálica Química orgánica de los metales.
  • La catálisis es la catálisis.

Sus antecedentes:

  • Los catalizadores de metaloceno son cruciales para la polimerización de las olefinas, ya que ofrecen propiedades sintonizables.
  • Comprender la influencia de los co-iniciadores y contrarios en el rendimiento del catalizador es clave para controlar la microestructura del polímero.
  • La polimerización del propileno proporciona un sistema modelo para el estudio de complejos mecanismos catalíticos.

Objetivo del estudio:

  • Para investigar el efecto de diferentes co-iniciadores (metilaluminoxano, B (((C ((6) F ((5)) ((3), [Ph ((3) C][B ((6) C)))) sobre la polimerización del propileno mediante el uso de complejos asimétricos ansa-metaloceno.
  • Para aclarar la relación entre la estructura del catalizador, el co-iniciador y la resultante microestructura de polipropileno (PP).
  • Para explorar el impacto de la concentración de monómeros en el comportamiento del catalizador y la táctica del polímero.

Principales métodos:

  • Síntesis y aplicación de complejos asimétricos de ansa-metaloceno (Me(2) Y ((Ind) CpMMe(2)).
  • Experimentos de polimerización del propileno llevados a cabo a diferentes concentraciones de monómeros.
  • Análisis de la microestructura del polímero, incluyendo la táctica y las distribuciones de pentadas.
  • Modelado cinético para determinar parámetros catalíticos fundamentales (por ejemplo, propagación, velocidades de inversión).

Principales resultados:

  • Los catalizadores derivados de Me(2)Si(Ind)CpZrMe(2) funcionaron bajo condiciones de inversión de cadena rápida, con una microestructura de PP en gran medida independiente de la contraparte.
  • La táctica del polipropileno fue sensible a la concentración de monómeros con combinaciones específicas de catalizador / co-iniciador (Me(2) C(Ind) CpHfMe(2) / PMAO o [Ph(3) C][B(C(6) F(5)) ((4) ]).
  • Los catalizadores activados con B ((C ((6) F ((5)) ((3)) produjeron PP estereorregulado, con una microestructura invariante a la concentración de monómeros, lo que sugiere regímenes de funcionamiento consistentes.

Conclusiones:

  • La principal diferencia en el rendimiento del catalizador se debe al régimen de funcionamiento (tasas relativas de inserción frente a la inversión) en lugar de la estereoselectividad intrínseca.
  • El orden observado de los contadores con respecto al régimen operativo se desvía de las expectativas basadas en la capacidad de coordinación.
  • Este estudio proporciona información sobre el control matizado de la microestructura del polímero a través del diseño del catalizador y las condiciones de reacción en la polimerización de propileno catalizado por metaloceno.