Question 1

Which of the following statements best explains why thiols are more acidic than alcohols?

Accepted Answer

Sulfur is larger and more polarizable than oxygen, stabilizing the negative charge on the thiolate ion.

Question 2

Which reagent will convert ethanol ($$\mathrm{CH_3CH_2OH}) $$completely to its alkoxide ($$\mathrm{CH_3CH_2O^-}) in $$aqueous solution?

Accepted Answer

Sodium hydride ($$\mathrm{NaH})$$

Question 3

Which of the following alcohols is expected to be the most acidic in aqueous solution?

Accepted Answer

$$\mathrm{CF_3CH_2OH} (2$$,2,2-trifluoroethanol)

Question 4

What is the major product when 2-butanol reacts with concentrated $$\mathrm{H_2SO_4}$$ and heat?

Accepted Answer

2-butene

Question 5

During the acid-catalyzed dehydration of 3,3-dimethyl-2-butanol, a rearrangement occurs. What is the most likely rearrangement?

Accepted Answer

Hydride shift to form a more stable tertiary carbocation

Question 6

Which of the following best describes the mechanism for the reaction of a tertiary alcohol with HBr to form an alkyl bromide?

Accepted Answer

SN1 substitution

Question 7

Which of the following is a correct statement about the oxidation of alcohols?

Accepted Answer

Primary alcohols can be oxidized to aldehydes and further to carboxylic acids.

Question 8

What is the role of pyridine in the reaction of an alcohol with thionyl chloride ($$\mathrm{$$SOCl_2$$}$$)?

Accepted Answer

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

Question 9

Which of the following statements about sulfonate esters is FALSE?

Accepted Answer

They are weak bases and poor leaving groups.

Question 10

Which of the following best explains why large, branched alkyl groups decrease the acidity of alcohols?

Accepted Answer

They hinder solvation of the conjugate base, making it less stable.

Question 11

A primary alcohol is oxidized with PCC in methylene chloride. What is the expected product?

Accepted Answer

An aldehyde

Question 12

Which of the following is the correct order of reactivity for alcohol dehydration under acidic conditions?

Accepted Answer

Tertiary \u003e Secondary \u003e Primary

Question 13

What is the major product when 1-octanol is treated with $$\mathrm{$$SOCl_2$$}$$ and pyridine?

Accepted Answer

1-chlorooctane

Question 14

Which of the following best describes the reaction of a chiral secondary alcohol with $$\mathrm{Ph_3PBr_2} ($$triphenylphosphine dibromide)?

Accepted Answer

The configuration at the chiral center is inverted.

Question 15

Which of the following is a correct statement about the oxidation of thiols?

Accepted Answer

Thiols are oxidized at the sulfur atom to form disulfides or sulfonic acids.

Question 16

Which of the following is the best method to convert a primary alcohol to a bromide without rearrangement?

Accepted Answer

Treat with $$\mathrm{Ph_3PBr_2} in $$DMF

Question 17

Which of the following is the correct mechanism for the reaction of a primary alcohol with HBr?

Accepted Answer

SN2

Question 18

Which of the following statements about the formation of alkoxides is correct?

Accepted Answer

A stronger base than hydroxide, such as sodium hydride, is required for complete conversion.

Question 19

Which of the following best explains why triflate esters are more reactive than tosylate esters in nucleophilic substitution reactions?

Accepted Answer

Triflate anion is a much weaker base and thus a better leaving group.

Chapter 11: The Chemistry of Alcohols and Thiols – Study Notes

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