OAT Organic Chemistry Reactions 4

Question 1

Which reagent selectively reduces an ester to a primary alcohol without reducing isolated alkene groups?

Accepted Answer

LiAlH4

Answer

LiAlH4 is a strong enough hydride donor to reduce esters fully to primary alcohols, whereas NaBH4 cannot reduce esters.

Question 2

What product results from treating a ketone with hydroxylamine (NH2OH)?

Accepted Answer

Oxime

Answer

Hydroxylamine condenses with the carbonyl group of a ketone to form an oxime (C=N-OH) and water.

Question 3

In electrophilic aromatic substitution, nitrobenzene undergoes nitration to give primarily which isomer?

Accepted Answer

Meta-dinitrobenzene

Answer

The nitro group is a strong meta-director because it destabilizes carbocation intermediates at ortho and para positions.

Question 4

Which conditions convert a carboxylic acid to an acyl chloride?

Accepted Answer

SOCl2 or PCl5

Answer

Thionyl chloride (SOCl2) or phosphorus pentachloride (PCl5) replaces the OH of a carboxylic acid with Cl to give the acyl chloride.

Question 5

What type of reaction is the Beckmann rearrangement?

Accepted Answer

Conversion of a ketoxime to an amide via acid-catalyzed rearrangement

Answer

The Beckmann rearrangement converts a ketoxime to an amide under acidic conditions via a 1,2-shift of the group anti to the hydroxyl.

OAT - Optometry Admission Test Practice Test