A dyotropic reaction is a type of chemical reaction. It is when an organic compound changes its structure. Two substituents jump from one place on the molecule to another. It is a pericyclic valence isomerization when two sigma bonds move at the same time to a new place on the same molecule. Dyotropic reactions are important in organic chemistry. They can explain how certain reactions work. Dyotropic reactions can be a useful step in making large and complicated molecules. Dyotropic reactions were first described by Manfred T. Reetz in 1971. The name "dyotropic reaction" comes from the Greek word "dyo" meaning "two." "Rearrangement" means that the reaction changes the bonds between atoms on a single molecule.