KEY CONCEPT
While the dipole moment in the carbonyl group increases the intermolecular forces (and
therefore boiling points) of aldehydes and ketones relative to alkanes, this is not as
significant as the impact of hydrogen bonding seen in alcohols.MCAT EXPERTISE
The carbonyl carbon is the most common electrophile you’ll see on Test Day. Remember
why this group has a dipole moment: oxygen is more electronegative and pulls electrons
away from the carbon, making the carbon electrophilic and a good target for nucleophiles.FORMATION
Aldehydes and ketones can be produced by several mechanisms. An aldehyde can be obtained from
the partial oxidation of a primary alcohol, although only by pyridinium chlorochromate (PCC;
C 5 H 5 NH[CrO 3 Cl]). With any stronger oxidants, aldehydes will continue to be oxidized to carboxylic
acids. A ketone can be obtained from the oxidation of a secondary alcohol. This can be performed
using reagents ranging from sodium or potassium dichromate salts (Na 2 Cr 2 O 7 or K 2 Cr 2 O 7 ) to
chromium trioxide (CrO 3 ) to PCC. When oxidizing a secondary alcohol, there is no concern for
oxidizing too far because the reaction will stop at the ketone stage.
MCAT Concept Check 6.1:
Before you move on, assess your understanding of the material with these questions.What is the suffix for an aldehyde? For a ketone?Aldehyde: