Question 1

Which of the following sets of reagents and conditions can be used to reduce a cyclohexanone to cyclohexane, and what is the name of the reaction type?

Accepted Answer

1. Zn(Hg), HCl (Clemmensen reduction)

Question 2

Which of the following is a correct sequence for the Wolff-Kishner reduction of a ketone to an alkane?

Accepted Answer

1. NH2NH2, KOH, heat

Question 3

In the reaction of a conjugated ketone with Na in liquid NH3 followed by NH4Cl, what is the main transformation occurring?

Accepted Answer

Reduction of the carbonyl and selective reduction of one double bond (Birch reduction)

Question 4

Which of the following best describes the role of tris(triphenylphosphine)chlororhodium (Wilkinson's catalyst) in organic chemistry?

Accepted Answer

It catalyzes the selective hydrogenation of alkenes to alkanes under mild conditions.

Question 5

Which of the following is a plausible first step in the mechanism of the Birch reduction of a conjugated ketone?

Accepted Answer

Single electron transfer from sodium to the aromatic ring

Question 6

Which of the following is a significant application of Wilkinson's catalyst in the pharmaceutical industry?

Accepted Answer

Stereoselective hydrogenation of alkenes in the synthesis of drug intermediates

Question 7

Which of the following reagents would NOT be suitable for the reduction of a ketone to an alkane?

Accepted Answer

KMnO4, H2SO4

Question 8

What is the main product when cyclohexanone is treated with Zn(Hg) and HCl?

Accepted Answer

Cyclohexane

Question 9

Which of the following best explains why the Birch reduction selectively reduces one double bond in a conjugated system?

Accepted Answer

The electron transfer and protonation steps favor the formation of a non-conjugated diene

Question 10

Which of the following is the correct balanced equation for the Clemmensen reduction of cyclohexanone?

Accepted Answer

$$\mathrm{C_6H_{10}O} + 2\ \mathrm{H_2$} \xrightarrow{Zn(Hg),\ HCl} \mathrm{C_6H_{12}} + \mathrm{H_2O}$$

Question 11

Which of the following statements about the mechanism of the Wolff-Kishner reduction is correct?

Accepted Answer

It involves the formation of a hydrazone intermediate, which is then decomposed under basic conditions to yield an alkane.

Question 12

Which of the following is a key advantage of using Wilkinson's catalyst for alkene hydrogenation?

Accepted Answer

It allows for selective hydrogenation of alkenes in the presence of other functional groups.

Question 13

In the Birch reduction, what is the role of NH4Cl in the reaction sequence?

Accepted Answer

It acts as a proton source to quench the intermediate anion.

Question 14

Which of the following is a real-world example of the use of the Clemmensen reduction?

Accepted Answer

Conversion of acetophenone to ethylbenzene in the synthesis of styrene derivatives.

Reduction and Catalysis in Organic Chemistry – Step-by-Step Guidance

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