DAT DAT - Dental Admission Organic Chemistry: Functional Groups 2 — Questions and Answers
Question 1: Oxidation of a primary alcohol produces which compound?
- A ketone
- An aldehyde (Correct answer)
- A carboxylic acid directly
- An ether
Correct answer: An aldehyde
Mild oxidation of a primary alcohol produces an aldehyde; further oxidation yields a carboxylic acid.
Question 2: Tollens' reagent is used to distinguish aldehydes from ketones because:
- It reduces ketones to alcohols
- It oxidizes aldehydes, producing a silver mirror, while ketones do not react (Correct answer)
- It adds to the carbonyl of both classes
- It dehydrates aldehydes only
Correct answer: It oxidizes aldehydes, producing a silver mirror, while ketones do not react
Tollens' reagent (ammoniacal silver nitrate) oxidizes aldehydes to carboxylate ions while depositing silver metal as a characteristic mirror; ketones do not react.
Question 3: Saponification is defined as the base-catalyzed hydrolysis of:
- Amines
- Esters (Correct answer)
- Alcohols
- Ethers
Correct answer: Esters
Saponification is the reaction of an ester with a strong base (e.g., NaOH) to produce an alcohol and a carboxylate salt (soap).
Question 4: Which reaction converts a carboxylic acid into an amide?
- Esterification
- Reaction with an amine (acylation) (Correct answer)
- Reduction with LiAlH₄
- Oxidation with KMnO₄
Correct answer: Reaction with an amine (acylation)
An amide is formed when a carboxylic acid (or activated derivative) reacts with an amine, creating the -CONH- linkage and releasing water.
Question 5: Treating an alcohol with HBr produces:
- An ester
- An alkyl bromide (Correct answer)
- An ether
- A carboxylic acid
Correct answer: An alkyl bromide
The hydroxyl group (-OH) of an alcohol is substituted by bromine when treated with HBr, producing an alkyl halide via SN1 or SN2 mechanism.
Question 6: When a Grignard reagent (RMgX) reacts with a ketone, the product after aqueous workup is:
- A primary alcohol
- An ester
- A tertiary alcohol (Correct answer)
- A carboxylic acid
Correct answer: A tertiary alcohol
Grignard reagents add to the carbonyl of a ketone, and two carbon substituents already on the ketone carbon make the resulting alcohol tertiary after protonation.
DAT DAT - Dental Admission Organic Chemistry: Functional Groups 2
Oxidation of a primary alcohol produces which compound?