OAT Organic Chemistry Reactions 2

Question 1

Which reagent converts an alkene to a vicinal diol via a syn addition mechanism?

Accepted Answer

OsO4 followed by NaHSO3

Answer

OsO4 performs syn dihydroxylation, adding two OH groups to the same face of the alkene.

Question 2

What is the major product when toluene reacts with Cl2 in the presence of FeCl3?

Accepted Answer

Ortho- and para-chlorotoluene

Answer

The methyl group is an ortho/para director, so electrophilic aromatic substitution gives predominantly ortho and para products.

Question 3

Which of the following conditions promotes an E1 elimination reaction preferentially?

Accepted Answer

Weak base, polar protic solvent, high temperature

Answer

E1 is favored by weak bases, polar protic solvents, and elevated temperatures that stabilize carbocation intermediates.

Question 4

What product forms when an ester is treated with excess Grignard reagent followed by aqueous workup?

Accepted Answer

Tertiary alcohol

Answer

Excess Grignard reacts twice with the ester—first to give a ketone intermediate, then again—yielding a tertiary alcohol.

Question 5

In a Diels-Alder reaction, which diene conformation is required for the reaction to proceed?

Accepted Answer

S-cis

Answer

The diene must adopt the s-cis conformation so both ends can simultaneously bond to the dienophile.

OAT - Optometry Admission Test Practice Test