When two six-membered rings share a C-C bond, this bicyclic system is called a decalin. There are two possible arrangements; trans-decalin having two hydrogen atoms at the ring fusion on opposite sides of the rings, and cis-decalin having the two hydrogens at the ring fusion on the same side.

a. Draw?trans- and?cis-decalin using the chair form for the cyclohexane rings.

b. The trans isomer is more stable. Explain why.

decalin I trans-decalin H H cis-decalin