MCAT Organic Chemistry 3

Question 1

Which of the following reactions proceeds via a carbocation intermediate?

Accepted Answer

SN1 solvolysis of tert-butyl chloride in water

Answer

SN1 reactions proceed by unimolecular ionization to form a carbocation intermediate, favored by tertiary substrates in polar protic solvents.

Question 2

What is the IUPAC name for CH3CH(OH)CH2CH3?

Accepted Answer

2-butanol

Answer

The hydroxyl group is on C2 of the four-carbon chain, giving 2-butanol by IUPAC nomenclature.

Question 3

In the Fischer projection of D-glucose, which carbon bears the reference hydroxyl group that defines the D-configuration?

Accepted Answer

C5

Answer

In D-glucose, the highest-numbered chiral center (C5) has its –OH on the right in the Fischer projection, defining D-configuration by analogy to D-glyceraldehyde.

Question 4

Which reagent would best convert a carboxylic acid to a primary amine via a Curtius-type rearrangement?

Accepted Answer

DPPA (diphenylphosphoryl azide) followed by heat and hydrolysis

Answer

DPPA converts carboxylic acids to acyl azides, which rearrange on heating (Curtius rearrangement) to isocyanates; hydrolysis then gives primary amines.

Question 5

Which of the following correctly describes a nucleophilic addition reaction to a carbonyl compound?

Accepted Answer

The nucleophile attacks the electrophilic carbonyl carbon

Answer

Nucleophilic addition to carbonyls occurs because the carbonyl carbon is electrophilic due to the electronegative oxygen withdrawing electron density.

MCAT - Medical College Admission Test Practice Test

MCAT - Medical College Admission Test Practice Test

MCAT Organic Chemistry 3