Question

What products would you obtain from catalytic hydrogenation of the following alkenes?

Short answer

Alkenes react with hydrogen in presence of either charcoal supported palladium or Pt, to generate the corresponding alkane and the whole reaction is also known as hydrogenation of alkenes. It’s a heterogenous process occurring with syn chemistry because both the hydrogens add from the same face of double bond.

Step-by-step solution

Catalytic hydrogenation

Alkenes react with hydrogen in presence of either charcoal supported palladium or Pt, to generate the corresponding alkane and the whole reaction is also known as hydrogenation of alkenes. It’s a heterogenous process occurring with syn chemistry because both the hydrogens add from the same face of double bond.

Explanation

a) The product formed will be 2-methyl pentane.

b) In the product formed, the addition of hydrogens will occur from the same face of the ring, so the product formed will be cis-1,1-dimethyl cyclopentane

c) Here, in the molecule, there is more steric hinderance if the addition of hydrogens occur from below the ring due to presence of isopropyl group at equatorial position. Therefore the addition of hydrogen will occur from above.