Related Experiment Video
Updated: Jun 5, 2025
05:48
Controlled Photoredox Ring-Opening Polymerization of O-Carboxyanhydrides Mediated by Ni/Zn Complexes
Published on: November 21, 2017
8.0K
Mechanistic Investigation of a Photoredox Cycloaddition Chain Reaction
Annemarie A Lee1, John R Swierk1
1Department of Chemistry, Binghamton University, Binghamton, New York 13902, United States.
Journal of the American Chemical Society
|December 9, 2024
Summary
This study elucidates the mechanism of a ruthenium-catalyzed photoredox chain reaction. Oxygen plays a key role in chain propagation, influencing reaction kinetics.
Area of Science:
- Organic Chemistry
- Photocatalysis
- Reaction Mechanisms
Background:
- Photoredox catalysis is crucial for developing novel synthetic methods in organic chemistry.
- Mechanistic understanding of photoredox chain reactions remains limited.
Purpose of the Study:
- To rigorously characterize the mechanism and kinetics of a ruthenium-catalyzed photoredox chain [4 + 2] cyclization.
- To elucidate the role of oxygen in the reaction pathway.
Main Methods:
- Quantum yield (QY) measurements
- Transient absorption spectroscopy (TAS)
- Electrochemical analysis
- Kinetic modeling
Main Results:
- Oxygen acts as a secondary electron acceptor, facilitating chain propagation.
- Key kinetic competition between chain propagation and termination was identified.
- Rate constants for key steps were determined.
Conclusions:
- The study provides critical mechanistic insights into photoredox chain reactions.
- Understanding these mechanisms can guide the development of new catalytic systems.
![[DPEPhosbcpCu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
Related Concept Videos
01:16Cycloaddition Reactions: Overview
2.5K
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
2.5K
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
2.0K
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.
2.0K
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
3.5K
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.
3.5K
01:17Pericyclic Reactions: Introduction
8.2K
Pericyclic reactions are organic reactions that occur via a concerted mechanism without generating any intermediates. The reactions proceed through the movement of electrons in a closed loop to form a cyclic transition state, where rearrangement of the σ and π bonds yields specific products.
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
Pericyclic reactions can be classified into three categories: electrocyclic reactions, cycloaddition reactions, and sigmatropic rearrangements. Electrocyclic reactions and sigmatropic...
8.2K
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
1.8K
![[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2Ffiles%2Fmedia%2Fscience-education%2Fscience-education-thumbs%2F12417.jpg&w=3840&q=75)
01:16[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
10.1K
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
10.1K