MChem Master of Chemistry Master of Chemistry: 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 is a mild oxidant that stops at the aldehyde stage because it is used in anhydrous (non-aqueous) conditions, preventing further oxidation.

Question 2

In the 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 that both terminal carbons can interact with the dienophile in a concerted [4+2] cycloaddition.

Question 3

Which of the following best describes a 1,2-hydride shift in carbocation rearrangements?

Accepted Answer

A hydride migrates from an adjacent carbon to the carbocation center

Answer

In a 1,2-hydride shift, a hydride (H⁻) migrates from the carbon adjacent to the carbocation, generating a new (typically more stable) carbocation at the original position.

Question 4

What is the major product when 2-methylpropene reacts with HBr via Markovnikov addition?

Accepted Answer

2-bromo-2-methylpropane

Answer

Markovnikov's rule directs the proton to the less-substituted carbon, placing the bromine on the more-substituted (tertiary) carbon to give 2-bromo-2-methylpropane.

Question 5

Which spectroscopic feature is most diagnostic for a carbonyl group (C=O) in IR spectroscopy?

Accepted Answer

Strong absorption around 1630–1850 cm⁻¹

Answer

The C=O stretch produces a strong, sharp absorption in the 1630–1850 cm⁻¹ region; the exact position depends on the type of carbonyl compound.

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Practice Test

MChem Master of Chemistry Master of Chemistry: Organic Chemistry 2