Isomerization

Isomerization of saturated hydrocarbons includes skeletal rearrangements and cis-trans isomerization of substituted cycloalkanes. Different catalysts bring about different types of isomerization of hydrocarbons. Acids are the best known and most important catalysts inducing isomerization through a carbocationic process. Bronsted and Lewis acids, acidic solids, and superacids are used in different applications. Significant efforts have been made about the fabrication, characterization, and the use of bifunctional catalysts bearing both acidic and metallic sites in isomerization. Metals are able to induce hydrogenation/dehydrogenation, whereas acid sites are involved in skeletal isomerization. Besides skeletal rearrangements, alkenes may undergo double-bond migration and cis-trans isomerization. Double-bond migration, cis-trans isomerization, and skeletal isomerization are the characteristic isomerization transformations of alkenes in the presence of acidic catalysts. Double-bond migration and cis-trans isomerization are facile transformations that can be induced under mild conditions (relatively mild acids and low temperature).