Question

Stability of cycloalkanes can be explained on the basis of Baeyer strain theory. This theory is applicable only for cyclopropane, cyclobutane and cyclopentane. Stability of cyclohexane and its derivative can be explained by Mohr's theory. According to this theory cyclohexane exists in two forms chair and boat. The chair form is more stable than the boat form. Every carbon of chair form has an axial and equatorial bonds. Bulky groups are generally present at equatorial position. The preferred conformation of cyclohexane ring is the chain form, but when intramolecular hydrogen bonding is possible between the group 1 and 4 positions the molecule assume a boat form
According to Baeyer strain theory which cycloalkane is the most stable?

• A. Cyclohexane
• B. Cyclopentane
• C. Cyclopropane
• D. Cyclobutane

Answer 1

Answer: (B)

Baeyer predicted that a five membered ring compound would be the most stable. It has angle of deviation $=0.44^{\circ }$
And we know that stability $\propto \frac{1}{d}$