26-2 Electrocyclic Reactions Electrocyclic reactions are pericyclic reactions that involve the cyclization of a conjugated acyclic polyene -One z bond is broken,the other x bonds change position,a new o bond is formed,and a cyclic compound results -Reactions are reversible Heat triene cyclohexadiene favors cyclic product A conjugated triene A cyclohexadiene ·diene≠cyclobutene Heat favors open-chain product A conjugated diene A cyclobuteneElectrocyclic reactions are pericyclic reactions that involve the cyclization of a conjugated acyclic polyene •One p bond is broken, the other p bonds change position, a new σ bond is formed, and a cyclic compound results •Reactions are reversible • triene cyclohexadiene favors cyclic product • diene cyclobutene favors open-chain product 26-2 Electrocyclic Reactions