Question 1

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

Accepted Answer

Ethers cannot form hydrogen bonds with other ether molecules.

Question 2

What is the main reason lithium iodide is moderately soluble in ethers?

Accepted Answer

Lithium cations are strongly solvated by the ether’s lone pairs of electrons.

Question 3

Which of the following is the correct IUPAC name for the compound $$CH_3OCH_2CH_3$$?

Accepted Answer

Methoxyethane

Question 4

A chemist wants to synthesize an ether using the Williamson ether synthesis. Which combination of reactants would be most effective?

Accepted Answer

A primary alkyl halide and a strong alkoxide

Question 5

Why can’t phenyl halides be used in the Williamson ether synthesis?

Accepted Answer

An $$S_N2$$ reaction cannot occur on an $$sp^2$$ carbon.

Question 6

Which of the following best describes the IR spectrum of an ether?

Accepted Answer

A C—O stretch in the fingerprint region (1000–1200 cm$$^{-1}) $$without C=O or OH stretches

Question 7

What is the product when diethyl ether is heated with concentrated HI?

Accepted Answer

Two moles of ethyl iodide and water

Question 8

Why are ethers commonly used as solvents in Grignard reactions?

Accepted Answer

Ethers stabilize the Grignard reagent by complexing with the magnesium ion.

Question 9

Which of the following statements about crown ethers is correct?

Accepted Answer

Crown ethers can complex metal cations in the center of the ring, allowing polar salts to dissolve in nonpolar solvents.

Question 10

What is the main safety concern when storing ethers for long periods?

Accepted Answer

Ethers can slowly oxidize to form highly explosive hydroperoxides and dialkyl peroxides.

Question 11

Which of the following is a key difference between thioethers and ethers?

Accepted Answer

Thioethers are more easily oxidized to sulfoxides and sulfones than ethers are to hydroperoxides.

Question 12

Which reagent is commonly used to convert alkenes to epoxides?

Accepted Answer

Meta-chloroperoxybenzoic acid (MCPBA)

Question 13

In the acid-catalyzed opening of an epoxide, where does the nucleophile attack?

Accepted Answer

At the most substituted carbon of the protonated epoxide

Question 14

What is the expected product when a Grignard reagent reacts with an epoxide?

Accepted Answer

The Grignard attacks the least hindered carbon, forming a primary alcohol after workup.

Question 15

Which of the following best describes the molecular orbital structure of buta-1,3-diene?

Accepted Answer

All atoms are $$sp^2$$ hybridized with overlapping $$p$$ orbitals, resulting in delocalized electrons.

Question 16

Why is the heat of hydrogenation for conjugated double bonds less than the sum for isolated double bonds?

Accepted Answer

Conjugated double bonds have extra resonance stabilization, releasing less energy upon hydrogenation.

Question 17

Which of the following is true about the base-catalyzed ring opening of epoxides?

Accepted Answer

The nucleophile attacks the least hindered carbon, releasing ring strain.

Question 18

What is the main function of silyl ethers in organic synthesis?

Accepted Answer

They are used as protecting groups for alcohols, resistant to some acids and bases.

Question 19

Which of the following statements about the regioselectivity of epoxide opening is correct?

Accepted Answer

In base, the nucleophile attacks the least hindered carbon; in acid, it attacks the most substituted carbon.

Chapter 14: Ethers, Epoxides, and Thioethers – Structure, Properties, and Reactivity

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