Advices For Studying Organic Chemistry

1. Cyclopentane has little torsional strain and angle strain.
   
   
   1. The internal angles are 108° ⇒ very little angle strain if it was planar ⇒
      considerably torsional strain.
   
   
   2. Cyclopentane assumes a slightly bent conformation ⇒ relieves some of the
      torsional strain.
   
   
   3. Cyclopentane is flexible and shifts rapidly form one conformation to another.
   
   
   
   

4.12 CONFORMATIONS OF CYCLOHEXANE

1. The most stable conformation of the cyclohexane ring is the “chair”
   conformation:

Figure 4.12 Representations of the chair conformation of cyclohexane: (a) Carbon
skeleton only; (b) Carbon and hydrogen atoms; (c) Line drawing; (d)
Space-filling model of cyclohexane. Notice that there are two types of
hydrogen substituents--those that project obviously up or down (shown
in red) and those that lie around the perimeter of the ring in more
subtle up or down orientations (shown in black or gray). We shall

discuss this further in Section 4.13.

1. The C—C bond angles are all 109.5° ⇒ free of angle strain.


2. Chair cyclohexane is free of torsional strain: