Learn · Organic Chemistry

The Cyclohexane Chair Flip

How a ring flip trades axial for equatorial — and why bulky groups pick the roomy seat.

Quick answer A cyclohexane chair flip rotates the ring's bonds so every axial position becomes equatorial and vice versa. It does not turn the molecule over — an "up" group stays up, it just switches seats.

1. Cyclohexane rests as a puckered chair, not a flat hexagon.

The staggered chair removes all torsional and angle strain, making it cyclohexane's lowest-energy shape.

Cyclohexane

2. Each carbon carries one axial and one equatorial position.

Axial bonds point straight up or down; equatorial bonds splay outward around the ring's rim.

Methylcyclohexane

3. The ring flip interconverts the two chair forms.

Bonds rotate so every axial group becomes equatorial and every equatorial group becomes axial.

Same molecule, seats swapped

4. The flip does not move the molecule in space.

An "up" substituent stays up throughout — it only switches between the axial and equatorial slot.

Chlorocyclohexane

5. Bulky groups prefer equatorial, so tert-butyl locks the ring.

Axial groups suffer 1,3-diaxial strain, so the chair holding a large group equatorial dominates the equilibrium.

tert-Butylcyclohexane

6. Summary

Chair is lowest-energy · flip swaps axial↔equatorial · molecule doesn't turn over · passes through half-chair & twist-boat · bulky group takes equatorial · tert-butyl locks the ring.

Quiz yourself

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It swaps them: every axial position becomes equatorial and every equatorial position becomes axial.

No. Up stays up — the flip only switches it between axial and equatorial, it does not turn the molecule over.

The chair that places the substituent equatorial, avoiding 1,3-diaxial strain.

The bulky tert-butyl group has a huge axial penalty, so the all-equatorial chair is overwhelmingly favored — the ring barely flips.

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