MCAT Organic Chemistry 2

Question 1

Which reagent converts a primary alcohol to an aldehyde without over-oxidizing to a carboxylic acid?

Accepted Answer

PCC (pyridinium chlorochromate)

Answer

PCC selectively oxidizes primary alcohols to aldehydes and stops there because it lacks aqueous conditions needed for further oxidation.

Question 2

In an E2 elimination reaction, what is the required geometric relationship between the leaving group and the beta hydrogen?

Accepted Answer

Anti-periplanar (180°)

Answer

E2 requires an anti-periplanar arrangement (180°) so that the breaking bonds can align with the forming pi bond in a concerted step.

Question 3

Which type of isomerism is exhibited by cis- and trans-2-butene?

Accepted Answer

Geometric (cis/trans) isomerism

Answer

Cis- and trans-2-butene are geometric isomers because they have the same connectivity but differ in the spatial arrangement of groups around the double bond.

Question 4

What product forms when an alkene reacts with ozone (O3) followed by a reductive workup (Zn, H2O)?

Accepted Answer

Two carbonyl compounds (aldehydes/ketones)

Answer

Ozonolysis with reductive workup cleaves the double bond to give two carbonyl compounds; aldehydes if the carbon was =CH2, ketones if disubstituted.

Question 5

Which statement best describes the inductive effect of a fluorine substituent on benzoic acid?

Accepted Answer

It withdraws electrons inductively, lowering pKa

Answer

Fluorine is highly electronegative and withdraws electron density inductively, stabilizing the carboxylate anion and lowering the pKa (increasing acidity).

MCAT - Medical College Admission Test Practice Test

MCAT - Medical College Admission Test Practice Test

MCAT Organic Chemistry 2