Question 1

Which of the following best describes the significance of free radical halogenation in organic synthesis?

Accepted Answer

It allows for the conversion of unreactive alkanes into functionalized hydrocarbons, enabling further chemical transformations.

Question 2

What is the first step in the radical halogenation of alkanes?

Accepted Answer

Initiation, where diatomic halogen molecules are split into radicals.

Question 3

Which of the following best represents the initiation step in the radical halogenation of methane with chlorine?

Accepted Answer

$$\mathrm{Cl_2$ \xrightarrow{hv} 2Cl^\cdot}$$

Question 4

During the propagation step of radical halogenation, which of the following reactions occurs?

Accepted Answer

$$\mathrm{CH_4$ + Cl^\cdot \rightarrow CH_3$^\cdot + HCl}$$

Question 5

Which of the following is a termination step in the radical halogenation mechanism?

Accepted Answer

$$\mathrm{Cl^\cdot + Cl^\cdot \rightarrow Cl_2$}$$

Question 6

Why are alkanes considered unreactive under normal conditions?

Accepted Answer

They lack functional groups and have strong C–H and C–C bonds.

Question 7

In the radical halogenation of propane, which product is favored and why?

Accepted Answer

2-chloropropane, because the secondary radical intermediate is more stable than the primary radical.

Question 8

Which of the following best explains why radical halogenation is considered a chain reaction?

Accepted Answer

Radicals generated in one step initiate further reactions, propagating the process.

Question 9

A student attempts to halogenate ethane with bromine under room temperature and observes no reaction. What is the most likely reason?

Accepted Answer

Bromine requires heat or light to initiate radical formation.

Question 10

Which of the following is a possible real-world application of radical halogenation?

Accepted Answer

Functionalizing hydrocarbons from petroleum to create intermediates for pharmaceuticals.

Question 11

Given the following reaction: $$\mathrm{CH_4$ + Cl_2$ \xrightarrow{hv} CH_3Cl + HCl}$$, which compound acts as the radical initiator?

Accepted Answer

Chlorine ($$\mathrm{Cl_2$})$$

Question 12

Which of the following statements about the selectivity of halogenation is correct?

Accepted Answer

Bromine is more selective than chlorine in radical halogenation reactions.

Question 13

Which of the following best describes the role of light in the radical halogenation of alkanes?

Accepted Answer

It provides energy to homolytically cleave the halogen molecule, generating radicals.

Question 14

Which of the following is NOT a possible termination step in a radical halogenation reaction?

Accepted Answer

$$\mathrm{CH_4$ + Cl_2$ \rightarrow CH_3Cl + HCl}$$

Question 15

Which of the following best explains why radical halogenation is important for the chemical industry?

Accepted Answer

It enables the transformation of unreactive hydrocarbons into valuable intermediates for further synthesis.

Radical Halogenation of Alkanes: Mechanism and Synthetic Importance

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