konrotatorisk

Konrotatorisk is a term used in chemistry to describe electrocyclic reactions in which the terminal p orbitals rotate in the same direction during the formation or cleavage of a new sigma bond. In English this is called conrotatory. Konrotatoriska processes are a subset of pericyclic reactions and are contrasted with disrotatoriska (disrotatory) processes, where the terminal orbitals rotate in opposite directions.

According to the Woodward–Hoffmann rules, the mode of rotation depends on the number of π electrons and whether the reaction is thermal or photochemical. For thermal electrocyclic reactions involving 4n π electrons, ring opening or closure proceeds conrotatory; for 4n+2 π electrons, thermal processes proceed disrotatory. Photochemical reactions can invert these patterns in many cases.

Examples include the thermal ring opening of cyclobutene to butadiene, a 4 π-electron system, which occurs conrotatorily; and the thermal ring closure of hexatriene to cyclohexadiene, a 6 π-electron (4n+2) system, which proceeds disrotatorily. These stereochemical outcomes reflect the concerted rotation of terminal p orbitals predicted by the konrotatorisk model.

Understanding konrotatorisk behavior aids in predicting the stereochemistry of electrocyclic reactions and informs synthetic strategy in organic chemistry.

See also pericyclic reactions, electrocyclic reactions, Woodward–Hoffmann rules.