Question 1

Which of the following statements best describes the general concept of reduction in organic chemistry?

Accepted Answer

Reduction is the process of increasing the number of carbon-hydrogen bonds or decreasing the number of carbon-oxygen bonds in a molecule.

Question 2

Which reagent is most suitable for the selective reduction of aldehydes to primary alcohols, but not esters?

Accepted Answer

NaBH4

Question 3

A chemist wants to reduce a carboxylic acid to a primary alcohol. Which reagent should they use?

Accepted Answer

LiAlH4

Question 4

Which of the following statements correctly compares NaBH4 and LiAlH4 as reducing agents?

Accepted Answer

LiAlH4 is more reactive and can reduce esters and carboxylic acids, while NaBH4 is milder and typically reduces only aldehydes and ketones.

Question 5

Which of the following is a necessary condition for the successful formation of a Grignard reagent?

Accepted Answer

The alkyl halide must be dissolved in an aprotic solvent such as ether.

Question 6

A student attempts to prepare a Grignard reagent from 2-bromopropane in the presence of water. What is the most likely outcome?

Accepted Answer

The Grignard reagent will react with water to produce propane and Mg(OH)Br.

Question 7

Which type of alkyl halide is least suitable for the formation of Grignard reagents?

Accepted Answer

Alkyl fluorides

Question 8

What is the product when an alcohol reacts with PBr3?

Accepted Answer

An alkyl bromide

Question 9

During the reaction of an alcohol with SOCl2, which critical intermediate is formed?

Accepted Answer

An alkyl sulfonate ester

Question 10

Which reagent is commonly used for the dehydration (elimination) of alcohols to form alkenes?

Accepted Answer

POCl3

Question 11

A chemist wants to oxidize a primary alcohol to an aldehyde without further oxidation to a carboxylic acid. Which reagent should be used?

Accepted Answer

DMP (Dess-Martin periodinane)

Question 12

Which of the following is a key difference between chromium-based oxidizing reagents and DMP?

Accepted Answer

DMP is milder and can oxidize primary alcohols to aldehydes without further oxidation, while chromium-based reagents often oxidize primary alcohols all the way to carboxylic acids.

Question 13

Which protecting group is commonly used to protect alcohols during multi-step organic synthesis?

Accepted Answer

Silyl ethers

Question 14

Why are silyl ethers used as protecting groups for alcohols in organic synthesis?

Accepted Answer

They prevent alcohols from reacting with strong bases and nucleophiles.

Question 15

A chemist needs to perform a Grignard reaction on a molecule containing both a ketone and an alcohol group. What should they do to ensure the Grignard reagent reacts only with the ketone?

Accepted Answer

Protect the alcohol group as a silyl ether before adding the Grignard reagent.

Question 16

Which of the following reactions is an example of an elimination reaction involving alcohols?

Accepted Answer

Alcohol + POCl3 $$\rightarrow$$ Alkene

Question 17

Which of the following is the correct balanced equation for the reduction of acetone ($$CH_3COCH_3) to $$isopropanol ($$CH_3CHOHCH_3) $$using NaBH4?

Accepted Answer

$$CH_3COCH_3 + $$NaBH_4$$ + H_2O \rightarrow CH_3CHOHCH_3 + $$NaBO_2$$

Question 18

Which of the following is NOT a plausible product when a primary alcohol is treated with CrO3/H2SO4?

Accepted Answer

Ketone

Question 19

In a medical case, a patient is exposed to methanol. Which reagent would be used in the laboratory to convert methanol to formaldehyde for toxicology analysis?

Accepted Answer

CrO3/H2SO4

Question 20

Which of the following best explains why Grignard reagents are incompatible with molecules containing acidic protons?

Accepted Answer

Grignard reagents are strong bases and will react with acidic protons, destroying the reagent.

Alcohols: Reduction, Oxidation, Grignard Reactions, and Protecting Groups

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