Question 1

Which of the following statements best explains why the Williamson ether synthesis fails when using tert-butyl iodide and methanol as shown in the first image?

Accepted Answer

Tert-butyl iodide is too sterically hindered for SN2 substitution, leading to elimination or no reaction.

Question 2

In the acid-catalyzed hydration of an alkene shown in the second image, what is the major product and why?

Accepted Answer

The major product is the Markovnikov alcohol because the more substituted carbocation intermediate is favored.

Question 3

Why must laboratory samples of ethers be tested for peroxides before use, as shown in the third image?

Accepted Answer

Ethers can form explosive hydroperoxides upon exposure to oxygen via a free radical mechanism.

Question 4

Which of the following best describes the stereochemistry of the product formed when cyclohexene reacts with $$\mathrm{Br_2$}$$ and $$\mathrm{H_2O} as $$shown in the fourth image?

Accepted Answer

A racemic mixture of trans-1-bromo-2-hydroxycyclohexane is formed.

Question 5

Which of the following is the correct IUPAC name for the compound shown in the eighth image (an aromatic ring with an ethoxy group)?

Accepted Answer

Ethoxybenzene

Question 6

What is the role of NaH in the Williamson ether synthesis as shown in the first and ninth images?

Accepted Answer

NaH deprotonates the alcohol to generate a strong nucleophile (alkoxide).

Question 7

Which of the following statements about crown ethers is correct?

Accepted Answer

Crown ethers increase the solubility of metal cations in organic solvents by encapsulating the cation.

Question 8

Which of the following best explains why epoxides are more reactive toward nucleophilic attack than other ethers?

Accepted Answer

Epoxides have significant ring strain, making ring opening thermodynamically favorable.

Question 9

In the reaction of an epoxide with NaCN followed by $$\mathrm{H_3O^+} (as $$shown in the twelfth and thirteenth images), what is the major product?

Accepted Answer

A cyanohydrin with cyanide on the less hindered carbon and hydroxyl on the other.

Question 10

Which of the following reagents would you use to oxidize a sulfide to a sulfoxide?

Accepted Answer

Sodium metaperiodate ($$\mathrm{$$NaIO_4$$})$$

Question 11

Which of the following best describes the regioselectivity of epoxide ring opening under basic conditions?

Accepted Answer

The nucleophile attacks the less substituted carbon due to SN2 mechanism.

Question 12

Which of the following is a correct statement about the oxidation of thiols to disulfides, as shown in the sixth image?

Accepted Answer

Thiols are oxidized to disulfides via an SN2 mechanism using bromine under basic conditions.

Question 13

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 14

Which of the following is a correct statement about the use of Grignard reagents with epoxides in synthesis?

Accepted Answer

Grignard reagents open epoxides to install a new carbon chain with the functional group on the second carbon.

Question 15

Which of the following is true about the Sharpless epoxidation?

Accepted Answer

It uses a chiral catalyst to produce enantioselective epoxidation of allylic alcohols.

Question 16

Which of the following best describes the product of acid-catalyzed ring opening of an epoxide with ethanol, as shown in the fifteenth and sixteenth images?

Accepted Answer

A trans-1-ethoxy-2-hydroxy product with inversion at the attacked carbon.

Ethers, Epoxides, Thiols, and Sulfides: Structure, Synthesis, and Reactions

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