Question 1

Which of the following best explains why the C–O–C bond angle increases from water to di-tert-butyl ether?

Accepted Answer

The increasing size of the alkyl groups causes greater steric repulsion, forcing the bond angle to widen.

Question 2

Which property of tetrahydrofuran (THF) explains its higher boiling point compared to diethyl ether?

Accepted Answer

THF is more polar, leading to stronger dipole-dipole interactions.

Question 3

Why does 1-butanol have a much higher boiling point than diethyl ether, despite similar molecular weights?

Accepted Answer

1-butanol forms strong intermolecular hydrogen bonds, while diethyl ether does not.

Question 4

Which of the following best describes the interaction between a crown ether and a potassium ion ($$K^+$$)?

Accepted Answer

The interior-facing oxygen atoms of the crown ether coordinate with $$K^+$$, forming a stable complex.

Question 5

What is the main advantage of using 18-crown-6 in the reaction of potassium fluoride with 1-bromooctane in benzene?

Accepted Answer

It solubilizes $$K^+$$, allowing $$F^- to $$act as a nucleophile in the organic phase.

Question 6

Which of the following statements about the Williamson Ether Synthesis is correct?

Accepted Answer

It is most effective with primary or methyl alkyl halides due to the SN2 mechanism.

Question 7

What is a significant safety concern when using ethers as solvents in the laboratory?

Accepted Answer

Ethers can oxidize to form unstable and shock-sensitive hydroperoxides.

Question 8

Which product is formed when sec-butyl methyl ether is heated with HBr?

Accepted Answer

2-Bromobutane and bromomethane

Question 9

Which of the following best describes the regioselectivity of nucleophilic attack on an unsymmetrical epoxide under basic conditions?

Accepted Answer

The nucleophile attacks the less substituted carbon due to lower steric hindrance.

Question 10

Which reagent is commonly used for the enantioselective epoxidation of allylic alcohols (Sharpless Epoxidation)?

Accepted Answer

$$t-$$Butyl hydroperoxide, titanium(IV) isopropoxide, and diethyl tartrate

Question 11

What is the product of the reaction between ethylene oxide and a Grignard reagent ($$RMgX$$), followed by acidic workup?

Accepted Answer

A primary alcohol with two additional carbon atoms

Question 12

Which of the following is true about the oxidation of sulfides?

Accepted Answer

Sulfides can be oxidized to sulfoxides and further to sulfones.

Question 13

Which IR absorption is characteristic of the S=O stretch in dimethyl sulfoxide?

Accepted Answer

$$
u = 1050\ \mathrm{cm}^{-1}$$

Question 14

In $$^1H $$NMR spectroscopy, where do the protons adjacent to an ether oxygen ($$H–C–O–R) $$typically appear?

Accepted Answer

$$\delta = 3.2 - 4.0$$

Question 15

Which of the following best explains why sulfide carbons ($$C–S–C) $$are more shielded in $$^{13}C $$NMR than ether carbons ($$C–O–C$$)?

Accepted Answer

Sulfur is less electronegative than oxygen, so it withdraws less electron density from the carbon.

Question 16

Which of the following is the correct IUPAC name for the compound $$CH_3CH_2OCH_2CH_3$$?

Accepted Answer

Ethoxyethane

Question 17

What is the functional group present in oxirane?

Accepted Answer

Epoxide

Question 18

Which of the following best describes the mechanism for the formation of epoxides from vicinal halohydrins?

Accepted Answer

Intramolecular SN2 reaction promoted by base

Question 19

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

Accepted Answer

Ethers are generally unreactive but can be cleaved by strong acids such as HI or HBr.

Chemistry of Ethers, Epoxides, and Sulfides: Structure, Properties, Synthesis, and Reactions

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