Q 3-3-54 E - Organic Chemistry (Mcmurry)

Question

In the next chapter we’ll look at cycloalkanes—saturated cyclic hydrocarbons—and we’ll see that the molecules generally adopt puckered, nonplanar conformations. Cyclohexane, for instance, has a puckered shape like a lounge chair rather than a flat shape. Why?

Step-by-Step Solution

Answer

In puckered structure, the angle strain is less than in the flat structure because in puckered atom occupies a tetrahedral position having an angle but in a flat the C-C-C angle is 120^o.

Puckered form

In this arrangement, the atoms occupy the tetrahedral position in which one atom is surrounded by the 3 atoms and forms a tetrahedron and the angle between the carbon is $109°28\text{'}$.

Flat form

In this the atom is arranged in to the triangular planer shape that a plane triangle is from by the three carbon atom forming C-C-C linkages and forming the angle 120^o.

Puckered form is preferred over flat form

The puckered form is preferred over the flat form because in the puckered from the angle strain is less and in the flat form, the angle strain is more due to which puckered form becomes more stable because the angle is $109°28\text{'}$ but in the flat the C-C-C angle is $120°$ hence the angle strain is more make the molecule less stable.