Lewis Acid Catalysis
Lewis Acid Catalysis - Related Videos
02:33
Lewis Acids and Bases
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2020
In 1923, G. N. Lewis proposed a generalized definition of acid-base behavior in which acids and bases are identified by their ability to accept or to donate a pair of electrons and form a coordinate covalent bond. A coordinate covalent bond (or dative bond) occurs when one of the atoms in the bond provides both bonding electrons. For example, a coordinate covalent bond occurs when a water molecule combines with a hydrogen ion to form a hydronium ion. A coordinate covalent bond also results when...
02:16
Lewis Acids and Bases
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2023
This lesson delves into Lewis acids and bases in the context of the octet rule for electron-deficient compounds. Here, the concept is discussed, emphasizing the group 13 elements like boron or aluminium. Since group 13 elements possess three valence electrons, they form trivalent compounds with a sextet of electrons and a vacant orbital for the central atom. Consequently, these electron-deficient compounds accept electrons from other species to complete their octet in a chemical reaction. They...
09:00
Lewis Acid-Base Interaction in Ph3P-BH3
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2023
Source: Tamara M. Powers, Department of Chemistry, Texas A&M University One of the goals of chemistry is to use models that account for trends and provide insights into the properties of reactants that contribute to reactivity. Substances have been classified as acids and bases since the time of the ancient Greeks, but the definition of acids and bases has been modified and expanded over the years.1 The ancient Greeks would characterize substances by taste, and defined acids as those that...
02:50
Catalysis
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2020
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams. The illustrated image represents the reaction diagrams for an endothermic chemical process progressing in the absence (red curve) and presence (blue curve) of a catalyst. Both...
08:23
Introduction to Catalysis
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2015
Source: Laboratory of Dr. Ryan Richards — Colorado School of Mines Catalysis is among the most important fields of modern technology and presently accounts for approximately 35% of the gross domestic product (GDP) and sustenance of approximately 33% of the global population through fertilizers produced via the Haber process.1 Catalysts are systems that facilitate chemical reactions by lowering the activation energy and influencing the selectivity. Catalysis will be a central technology in...
FAQs
Coordination to a lone pair or π bond changes the substrate’s electronic character. This increased electrophilicity makes the substrate more responsive to reaction partners, while stabilization of intermediates reduces the energetic cost of reaching the transition state. The result is a faster reaction pathway without requiring the catalyst to become part of the final product.
Regeneration allows the Lewis acid to participate in successive reaction cycles rather than being consumed in a single transformation. During the cycle, it activates the substrate and helps stabilize reactive intermediates, then returns to its catalytic form. This behavior supports efficient bond formation while using the catalyst to accelerate reactions under comparatively milder conditions.
Selectivity can reflect how effectively the Lewis acid controls substrate activation. Binding to a lone pair or π bond directs the catalyst toward a particular electronically activated site, and stabilization of the resulting intermediates influences which reaction pathway is favored. This control is especially relevant when designing carbonyl transformations, Friedel–Crafts reactions, or cycloadditions.
Aluminum chloride, boron trifluoride, and titanium compounds are cited as common Lewis acid catalysts. Their use supports several important organic transformations, including reactions of carbonyl compounds, Friedel–Crafts reactions, and cycloadditions. The appropriate catalyst-substrate pairing determines how activation and intermediate stabilization contribute to the desired bond-forming process.
The process begins when the Lewis acid coordinates with a substrate through a lone pair or π bond. That interaction increases electrophilicity and stabilizes reaction intermediates, lowering the activation energy for the transformation. After bond formation and product generation, the catalyst is regenerated, allowing the catalytic sequence to continue rather than ending with catalyst consumption.
This approach is useful when researchers need efficient bond formation, controlled substrate activation, or reaction conditions that are milder than those required without catalysis. Its applications include preparing pharmaceuticals, fine chemicals, and advanced materials. The range of supported transformations also makes it relevant to synthetic organic chemistry and materials-oriented chemical research.