Larger and Polycyclic Cycloalkanes

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Cycloalkanes with rings larger than cyclohexane lack its symmetry and have some strain, until we reach cyclotetradecane, wide enough for its carbons to adopt the perfect zigzag conformation of linear, acyclic alkanes.

Cyclotetradecane: its conformation matches two fused chair cyclohexane rings — Cyclotetradecane

Apart from cyclohexane, cycloalkanes have no true axial and equatorial positions. They appear again in cyclotetradecane and larger cycloalkanes.

Cycloheptane

Decalin (bicyclo[4.4.0]decane): cis-decalin has two conformations of equal energy and trans-decalin only one

The main page of this topic shows a good sample of polycyclic compounds. Rings can be fused in every imaginable way: the possibilities are unlimited.

Norbornane (bicyclo[2.2.1]heptane): a rigid molecule that cannot adopt a chair conformation

Carbon can tolerate a great deal of bond strain and, believe it or not, compounds such as these have been made in the laboratory:

Tetra-tert-butyltetrahedrane — Tetra-*tert*-butyltetrahedrane