Functional Groups are the Key

Functional groups in organic chemistry

The functional groups you learn in organic chemistry are not just lines and letters in your book. They can have a major impact on your life! Therefore, let’s take a look at the following case study to see…

A MEDICAL CASE INVOLVING THE CARBONYL GROUP

A 19-year-old incarcerated male presents stating that over the last week, he has been having increased urination, unquenchable thirst, and hunger. When the patient woke up this morning, he was having generalized abdominal pain and felt very dizzy as if he was “going to pass out.” He currently has nausea, but denies vomiting or diarrhea. Despite the nausea, the patient states he is hungry. He has lost 10 pounds over the last 2 weeks, even with adequate food intake. The patient denies any fever or chills. He denies any headache, acute visual changes, sore throat, shortness of breath, or chest pain. He has not experienced any dysuria or flank pain with his polyuria.

Diagnosis

Abdominal pain secondary to new-onset diabetic ketoacidosis.

What is going on?

Ketoacidosis is caused by an increase in structures that contain ketone functional groups within the body. There are two main components that contribute to this metabolic imbalance: acetoacetate (acetoacetic acid) and β-hydroxybutyrate (β-hydroxybutyric acid). Let’s take a look at these structures:

Here is how they are synthesized in the body:

Reactions involving carbon-Carbon bond formation

In order to make these carbon-carbon bonds, a nucleophile needs to be generated. A couple of classic reactions in organic chemistry that allow us to form carbon-carbon bonds are the Aldol Reaction and the Claisen Condensation:

Let’s begin by looking at the acid-catalyzed Aldol reaction mechanism:

The first step involves enol formation, which generates our nucleophile. We can think of this rearrangement (tautomerization) as going back and forth between the keto and enol forms. Once the enol forms, it can attack another molecule: (1) the hydrogen atom bonded to the oxygen in the enol is weakened by the hydrogen bonding with the carbonyl group of the aldehyde. This helps break the bond and the electrons from the oxygen-hydrogen bond ‘swing down’ reforming the carbonyl group; (2) the electrons from the enol double bond (our nucleophile) ‘swing out’ and attack the carbonyl group of the aldehyde; (3) the electrons of the aldehyde carbonyl group swing up and now form a formal bond with the hydrogen atom.

This reaction can also proceed using a base instead of an acid:

Now, see of you can write the mechanism for the Claisen Condensation reaction.

SIDE NOTE

A side reaction that can occur with beta-hydroxy carbonyl groups is dehydration. These readily eliminate to form alpha,beta-unsaturated carbonyl compounds: