Related Experiment Video
Updated: Jun 12, 2026
10:39
Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
Published on: August 23, 2018
Nonproductive events in ring-closing metathesis using ruthenium catalysts
Ian C Stewart1, Benjamin K Keitz, Kevin M Kuhn
1The Arnold and Mabel Beckman Laboratory of Chemical Synthesis, Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Journal of the American Chemical Society
|June 4, 2010
Summary
Ruthenium catalysts were studied for olefin metathesis reactions. A steric model explains how catalyst structure influences reaction efficiency, differentiating productive and nonproductive pathways.
Area of Science:
- Organic Chemistry
- Catalysis
- Organometallic Chemistry
Background:
- Olefin metathesis is a powerful carbon-carbon bond-forming reaction.
- Ruthenium-based catalysts are widely used for olefin metathesis.
- Understanding catalyst behavior in productive and nonproductive pathways is crucial for optimizing reactions.
Purpose of the Study:
- To compare the turnover numbers (TONs) of productive and nonproductive metathesis reactions.
- To investigate the influence of catalyst structure on reaction efficiency using different substrates.
- To propose a model explaining the observed trends in ruthenium-catalyzed metathesis.
Main Methods:
- Comparative analysis of eight different ruthenium-based catalysts.
- Evaluation of metathesis reactions with diethyl diallylmalonate and dimethyl allylmethylallylmalonate.
- Kinetic studies to determine relative efficiencies of productive and nonproductive pathways.
Main Results:
- Significant differences in TONs were observed between productive and nonproductive metathesis reactions.
- A ruthenium methylidene intermediate is proposed to be involved in nonproductive cross metathesis.
- Catalyst structure significantly impacts the relative efficiencies of different metathesis pathways, particularly for challenging substrates forming trisubstituted olefins.
Conclusions:
- The efficiency of ruthenium catalysts in olefin metathesis is highly dependent on catalyst structure.
- A steric model effectively explains the observed trends in catalyst performance.
- Further research into catalyst design can optimize olefin metathesis for specific synthetic goals.
Related Concept Videos
01:16Olefin Metathesis Polymerization: Ring-Opening Metathesis Polymerization (ROMP)
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...
01:13Olefin 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...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
02:26Base-Catalyzed Ring-Opening of Epoxides
Due to their highly strained structures, epoxides can readily undergo ring-opening reactions through nucleophilic substitution, either in the presence of an acid or a base. The nucleophilic substitution reactions in the presence of acid are called acid-catalyzed ring-opening reactions, and nucleophilic substitution reactions in the presence of a base are called base-catalyzed ring-opening reactions. Epoxides undergo base-catalyzed ring-opening reactions in the presence of a strong nucleophile...
02:24Acid-Catalyzed Ring-Opening of Epoxides
Epoxides that are three-membered ring systems are more reactive than other cyclic and acyclic ethers. The high reactivity of epoxides originates from the strain present in the ring. This ring strain acts as a driving force for epoxides to undergo ring-opening reactions either with halogen acids or weak nucleophiles in the presence of mild acid. The acid catalyst converts the epoxide oxygen, a poor leaving group, into an oxonium ion, a better leaving group, making the reaction feasible. The...
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
00:53Olefin 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...
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...