Problem
4-3
3-Ethyl-1,1-dimethylcyclopentane
Problem
4-6
The two hydroxyl groups are cis. The two side chains are trans.
Problem
4-8
Six interactions; 21% of strain
Problem
4-9
The cis isomer is less stable because the methyl groups nearly eclipse each other.
Problem
4-10
Ten eclipsing interactions; 40 kJ/mol; 35% is relieved.
Problem
4-11
Conformation (a) is more stable because the methyl groups are farther apart.
Problem
4-14
Before the ring-flip, red and blue are equatorial and green is axial. After the ring-flip, red and blue are axial and green is equatorial.
Problem
4-15
4.2 kJ/mol
Problem
4-16
Cyano group points straight up.
Problem
4-17
Equatorial = 70%; axial = 30%
Problem
4-20
trans-Decalin is more stable because it has no 1,3-diaxial interactions.
Problem
4-21
Both ring-fusions are trans.