What Is a Lewis Acid?

Lewis acid, also known as electrophilic reagent, refers to substances that can accept electron pairs (including ions, atomic groups or molecules), which is determined according to the definition of acid by Gilbert Newton Lewis' acid-base electron theory. Because it contains a wide range of substances, it is also called broad acid.

There are five types of Lewis acids: simple cations (in theory, all simple cations are Lewis acids), the electronic structure of the central atom is an incomplete octahedron (this is the most important Lewis acid), and the central atom The compound that can be enlarged by octahedron, the compound with a central atom having a heavy bond, and the elemental element of the hexahedron with an electronic structure. ^[1]

Lewis acids have great practical significance in acid-catalyzed reactions in organic chemistry. For example, Lewis acids such as aluminum trichloride, boron trifluoride, sulfur trioxide, and iron bromide are important acid catalysts. They can replace Bronsted acid catalysts in many reactions (such as sulfuric acid and hydrogen fluoride, etc.), and their catalytic performance is often superior to Bronsted acids. , But the use of Lewis acid can see the effect immediately. ^[1]