Question 1

Which of the following best describes the stereochemical outcome of the catalytic hydrogenation of an alkene using $$\mathrm{H}_2$$ and a Pt catalyst?

Accepted Answer

Syn addition of two hydrogens across the double bond

Question 2

Which of the following functional groups is LEAST likely to be reduced under standard catalytic hydrogenation conditions (Pt or Pd, $$\mathrm{H}_2$$)?

Accepted Answer

Aromatic ring

Question 3

A compound with the structure $$\mathrm{CH_3CH=$$CHCH_3$$} is $$subjected to catalytic hydrogenation using $$\mathrm{H}_2$$ and Pd. What is the major product?

Accepted Answer

$$\mathrm{CH_3CH_2CH_2CH_3}$$

Question 4

Why is catalytic hydrogenation of alkenes considered a heterogeneous reaction?

Accepted Answer

Because the catalyst is insoluble and the reaction occurs on its surface

Question 5

Which statement best explains why catalytic hydrogenation is selective for $$\mathrm{C=C}$$ bonds over $$\mathrm{C=O} or $$aromatic rings under normal conditions?

Accepted Answer

The catalyst surface preferentially binds alkenes over carbonyls and aromatics

Question 6

During the catalytic hydrogenation of a cyclic alkene, such as cyclohexene, what is the stereochemical relationship between the two newly added hydrogens?

Accepted Answer

They are added to the same face (syn addition)

Question 7

Which of the following is a necessary condition for the catalytic hydrogenation of an alkene?

Accepted Answer

Presence of a metal catalyst such as Pt or Pd

Question 8

A student attempts to hydrogenate benzene using $$\mathrm{H}_2$$ and Pt under standard conditions. What is the expected outcome?

Accepted Answer

Benzene remains unchanged

Question 9

Which of the following best describes the mechanism of catalytic hydrogenation of alkenes?

Accepted Answer

Both hydrogens are transferred simultaneously to the same face of the alkene on the catalyst surface

Question 10

Which of the following statements about the reduction of alkenes is FALSE?

Accepted Answer

Catalytic hydrogenation can reduce aromatic rings under standard conditions

Question 11

A mixture contains both an alkene and a ketone. When subjected to catalytic hydrogenation with $$\mathrm{H}_2$$ and Pd, what is the expected outcome?

Accepted Answer

Only the alkene is reduced; the ketone remains unchanged

Question 12

Which of the following best explains why syn addition occurs during catalytic hydrogenation?

Accepted Answer

Both hydrogens are delivered from the catalyst surface to the same face of the alkene

Question 13

Which of the following is NOT a typical catalyst for the hydrogenation of alkenes?

Accepted Answer

Copper (Cu)

Question 14

A chiral alkene is subjected to catalytic hydrogenation. What is the effect on the number of stereocenters in the product?

Accepted Answer

The number of stereocenters decreases

Question 15

Which of the following best describes the role of the metal catalyst in alkene hydrogenation?

Accepted Answer

It provides a surface for the adsorption and activation of hydrogen and alkene

Reduction of Alkenes: Catalytic Hydrogenation

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