Question 1

Which of the following best explains why alcohols are often protected before performing a Grignard reaction?

Accepted Answer

Alcohols are acidic and would react with the Grignard reagent, destroying it.

Question 2

In the protection of an alcohol using $$ (CH_3$)_3SiCl $$, what is the role of $$ (CH_3$)_2N $$?

Accepted Answer

It acts as a base to neutralize the HCl formed during the reaction.

Question 3

Which of the following ethers can be synthesized using the Williamson ether synthesis?

Accepted Answer

Cyclopentyl methyl ether

Question 4

Why is the Williamson ether synthesis generally limited to primary alkyl halides?

Accepted Answer

Secondary and tertiary alkyl halides tend to undergo elimination rather than substitution.

Question 5

Which of the following is the correct product of the reaction between cyclopentanol and methyl iodide in the presence of NaH and THF?

Accepted Answer

Cyclopentyl methyl ether

Question 6

What is the major product when $$ (CH_3$)_3SiOCH_2CH_2CH_2CH_2MgBr $$ reacts with acetone followed by aqueous workup?

Accepted Answer

$$ (CH_3$)_3SiOCH_2CH_2CH_2CH_2C(OH)(CH_3$)_2 $$

Question 7

Which of the following statements about ethers is TRUE?

Accepted Answer

Ethers are generally less reactive than alcohols due to the absence of an acidic hydrogen.

Question 8

In the oxymercuration reaction shown, what is the nucleophile that attacks the mercurinium ion intermediate?

Accepted Answer

Methanol ($$ CH_3OH )$$

Question 9

Which of the following is a correct IUPAC name for the compound shown: $$ C_6H_5OCH_2CH_3 $$?

Accepted Answer

Ethyl phenyl ether

Question 10

What is the function of $$ Bu_4N^+F^-  in $$the deprotection step of a silyl-protected alcohol?

Accepted Answer

It cleaves the Si-O bond, regenerating the free alcohol.

Question 11

Which of the following ethers is most likely to form peroxides upon standing in air?

Accepted Answer

Diethyl ether

Question 12

A student attempts to synthesize tert-butyl methyl ether using the Williamson ether synthesis. Which of the following is the best explanation for why this reaction fails?

Accepted Answer

Tert-butyl halides undergo elimination rather than substitution under SN2 conditions.

Question 13

Which of the following best describes the mechanism of the Williamson ether synthesis?

Accepted Answer

An $$ S_N2 $$ reaction between an alkoxide ion and a primary alkyl halide.

Question 14

Which of the following is a correct structure for p-dimethoxybenzene?

Accepted Answer

A benzene ring with methoxy groups at the 1 and 4 positions.

Question 15

Which of the following is a correct statement about the reactivity of Grignard reagents?

Accepted Answer

They react with water and alcohols, so these groups must be protected.

Question 16

A chemist wants to synthesize cyclohexyl ethyl ether from cyclohexene. Which sequence of reagents would accomplish this transformation?

Accepted Answer

$$ (CF_3CO)_2Hg, CH_3CH_2OH $$ followed by $$ $$NaBH_4$$ $$

Question 17

Which of the following is a correct product of the reaction between styrene, $$ (CF_3CO)_2Hg $$, $$ CH_3OH $$, and $$ $$NaBH_4$$ $$?

Accepted Answer

1-Methoxy-1-phenylethane

Question 18

Which of the following best describes the role of THF (tetrahydrofuran) in Grignard reactions?

Accepted Answer

It acts as a solvent that stabilizes the Grignard reagent.

Question 19

Which of the following ethers is aromatic?

Accepted Answer

Anisole

Question 20

Which of the following is a correct statement about the polarity of ethers?

Accepted Answer

Ethers are more polar than alkanes but less polar than alcohols.

Protecting Groups, Ethers, and Epoxides in Organic Synthesis

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