Question 1

Which of the following statements best explains why alcohols are poor substrates for direct $$S_N2$$ reactions with halide nucleophiles?

Accepted Answer

The hydroxyl group ($$-OH) is a $$poor leaving group and must be protonated or converted before substitution.

Question 2

A secondary alcohol reacts with HBr and forms two different products. Which mechanistic feature is most responsible for this mixture?

Accepted Answer

Carbocation rearrangement occurs after loss of water, leading to multiple products.

Question 3

Which of the following best describes the role of PCC (pyridinium chlorochromate) in organic synthesis?

Accepted Answer

It oxidizes primary alcohols to aldehydes and secondary alcohols to ketones.

Question 4

During the $$S_N1$$ reaction of a secondary alcohol with HBr, a hydride shift occurs. What is the main consequence of this shift?

Accepted Answer

It produces a rearranged product where the bromine attaches to a more substituted carbon.

Question 5

Which of the following is a key advantage of using $$PBr_3 to $$convert alcohols to alkyl bromides instead of using HBr?

Accepted Answer

It avoids carbocation rearrangements and works under milder conditions.

Question 6

In the Williamson ether synthesis, why is it preferable to use a primary alkyl halide rather than a tertiary alkyl halide?

Accepted Answer

Tertiary alkyl halides undergo elimination ($$E_2) $$rather than substitution ($$S_N2) $$with strong bases.

Question 7

Which of the following statements about ethers is correct?

Accepted Answer

Ethers are aprotic polar solvents with relatively low boiling points.

Question 8

A student attempts to synthesize an ether using the Williamson ether synthesis with 2-bromopropane and sodium ethoxide. What is the most likely major product?

Accepted Answer

An alkene formed by $$E_2$$ elimination.

Question 9

Which of the following best explains the regioselectivity observed when an unsymmetrical epoxide reacts with a neutral nucleophile under acidic conditions?

Accepted Answer

The nucleophile attacks the more substituted carbon because it bears more positive character ($$\delta^+) $$after protonation.

Question 10

Which of the following is true regarding the reaction of epoxides with nucleophiles under basic conditions?

Accepted Answer

The nucleophile attacks the less hindered carbon via an $$S_N2$$ mechanism.

Question 11

Which of the following is a correct statement about the hydride shift in carbocation rearrangements?

Accepted Answer

Hydride shifts are concerted processes that occur from the same side as the leaving group.

Question 12

Which of the following best describes the mechanism of the reaction between 1-butanol and $$PBr_3$$?

Accepted Answer

The reaction proceeds via an $$S_N2$$ mechanism after activation of the alcohol.

Question 13

Which of the following is NOT a requirement for a successful Williamson ether synthesis?

Accepted Answer

A tertiary alkyl halide as the electrophile.

Question 14

What is the main driving force for the ring-opening reactions of strained ethers such as epoxides?

Accepted Answer

Release of ring strain energy (approximately 27 kcal/mol).

Question 15

Which of the following statements about the reactivity of ethers is correct?

Accepted Answer

Ethers are generally inert and are often used as solvents in organic reactions.

Question 16

In the acid-catalyzed ring opening of an unsymmetrical epoxide with methanol, which product will predominate?

Accepted Answer

Methoxy group attaches to the more substituted carbon.

Question 17

Which of the following is a correct statement about alkyl shifts in carbocation rearrangements?

Accepted Answer

Alkyl shifts are more likely when there are no hydrogens available to shift.

Question 18

Which of the following best explains why ethers have lower boiling points than alcohols of similar molecular weight?

Accepted Answer

Ethers cannot form hydrogen bonds with themselves.

Question 19

Which of the following is the correct product when 1-butanol is treated with $$PBr_3$$?

Accepted Answer

1-bromobutane

Chapter 9: Further Reactions of Alcohols and the Chemistry of Ethers

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