Chapter 5, Problem 56P

(a)

Interpretation Introduction

Interpretation:

It should be determined that the number of alkenes used to prepare methylcyclopentane by hydrogenation process.

Concept introduction:

• The amount of heat released in a hydrogenation reaction is known as heat of hydrogenation$\left(\Delta H^0\right)$.
• The most stable alkene has the smallest heat of hydrogenation.
• The stability of an alkene increases as the number of alkyl substituents bonded to its $s{p}^2$ carbon increases.
• The stability of an alkene increases as the number of hydrogen bonded to its $s{p}^2$ carbon decreases.
  • Catalytic hydrogenation is the process of addition of hydrogen to a compound in the presence of a catalyst.  The most common metal catalyst is palladium, which is used as a powder absorbed on charcoal to maximize its surface area.  The metal catalyst is required to weaken the very strong $H-H$ bond.
  • A meso compound is a molecule with multiple stereocentres that is super imposable on its mirror image.

(b)

Interpretation Introduction

Interpretation:

Most stable alkene should be identified that which was used to prepare methylcyclopentane.

Concept introduction:

The amount of heat released in a hydrogenation reaction is known as heat of hydrogenation$\left(\Delta H^0\right)$.

The most stable alkene has the smallest heat of hydrogenation.

The stability of an alkene increases as the number of alkyl substituents bonded to its $s{p}^2$ carbon increases.

The stability of an alkene increases as the number of hydrogen bonded to its $s{p}^2$ carbon decreases.

(c)

Interpretation Introduction

Interpretation:

The alkene which has the smallest heat of hydrogenation should be identified.

Concept introduction:

The amount of heat released in a hydrogenation reaction is known as heat of hydrogenation$\left(\Delta H^0\right)$.

The most stable alkene has the smallest heat of hydrogenation.

The stability of an alkene increases as the number of alkyl substituents bonded to its $s{p}^2$ carbon increases.

The stability of an alkene increases as the number of hydrogen bonded to its $s{p}^2$ carbon decreases.