Free interactive chemistry · SIM-ORG-PERI-001
Pericyclic reactions
Ring closures that happen in one concerted step. Orbital symmetry decides the direction of rotation.
Open the interactive simulation →How to use this simulation
- Choose a 4π (diene) or 6π (triene) system.
- Choose heat (Δ) or light (hν).
- Watch the ends rotate so like-coloured lobes meet, and read the Woodward–Hoffmann rules.
What to notice
- Heat: 4π closes conrotatory, 6π disrotatory.
- Light flips the rule, because it changes the HOMO.
Try this
Predict the rotation for a 6π system under light, then check.
Try it for free →