Triacylglycerol Reactions: Oxidation: Study with Video Lessons, Practice Problems & Examples

In the oxidation of triacylglycerols, elemental oxygen (O₂) cleaves pi bonds, transforming them into carboxylic acids. This reaction involves the double-bonded carbons of triglycerides, which, upon cleavage, bond with oxygen to form carboxyl groups (-COOH) and hydroxyl groups (-OH). Understanding this process is crucial for grasping lipid metabolism and the role of oxidation in biochemical pathways, including the production of energy through aerobic respiration.

Triacylglycerol Reactions: Oxidation Concept 1

In this video, we're discussing a triacylglycerol reaction in the form of oxidation. Now, under this type of reaction, we're going to say that elemental oxygen O₂, cleaves pi bonds to create carboxylic acids. So, if we take a look here, here go our pi bonds in our original triglyceride molecule. And if we look at them, what's going to happen here is we're using atmospheric oxygen, elemental oxygen. It's going to cleave these pi bonds. And here, just for color coding, these three double-bonded carbons are these three double-bonded carbons. And then these three would be these three. I basically just cut them apart from each other. They still have their double bonds, but we're trying to make carboxylic acids now. So these carbons to make carboxylic acid, they're each going to double bond to oxygen. And to make it a carboxylic acid, they'll also be connected to an OH group. And the same thing on the other side. So in that way, we created carboxylic acids from our original double-bonded carbons. So that's the basis of this reaction. We're using environmental oxygen and atmospheric oxygen O₂ to cut or cleave the pi bond in order to create two carboxylic acids from the place where it's cut, the pi bond that's cut. So just keep this in mind when dealing with the oxidation of a triacylglycerol or a triglyceride molecule.

Which of the following triacylglycerols cannot undergo an oxidation reaction?

• A.
• B.
• C.
• D.

Match each of the following statements with hydrogenation (A), Acid-Catalyzed Hydrolysis (B), Saponification (C) or Oxidation (D).

I.  ____ Glycerol is one of the products created. 

II. ____ C=O bonds are created in the process. 

III. ____ C=C bonds are converted to C–C bonds in the process. 

IV. ____ Salts of fatty acids are some of the products created.

This practice question says, match each of the following statements with hydrogenation for A, acid catalyzed hydrolysis for B, saponification for C, or oxidation for D. Now, the first one says, glycerol is one of the products created. Glycerol is a product when we deal with hydrolysis. Whether it be acidic hydrolysis or acetylized hydrolysis, enzymatic or saponification, a glycerol molecule will be one of our products. So this one is actually B and C together. Next, it says, carbonyl bonds, so C double bonded to O, are created in the process. Here we're adding oxygen. If we're adding oxygen, at least from a biological aspect, that means we're undergoing oxidation. So here, this would be D. Next, we are changing carbon double bonded carbon bonds into carbon single bonded carbons in the process. So, we're adding hydrogens in order to do this. So this would have to be hydrogenation. Then finally, it says, salts of fatty acids are some of the products created. Now, acid catalyzed hydrolysis, enzymatic hydrolysis, and saponification all make glycerol as a product, but it's only saponification that makes salts of the fatty acids as another product. Here, this would be saponification which would be C. If I had said, fatty acids are some of the products created, then this would be acid catalyzed hydrolysis or enzymatic hydrolysis. Now, here we didn't put enzymatic hydrolysis as an option, that's because it makes the same products as acid catalyzed hydrolysis. The pathway may be different, but the end products are the same. Right. So this is how we describe each one of these statements in relation to A, B, C, and D when we talk about hydrogenation, acid catalyzed hydrolysis, saponification which is just basic hydrolysis, or oxidation.

Here’s what students ask on this topic:

What is the role of elemental oxygen (O₂) in the oxidation of triacylglycerols?

Elemental oxygen (O₂) plays a crucial role in the oxidation of triacylglycerols by cleaving the pi bonds in the double-bonded carbons of the triglyceride molecule. This cleavage transforms the double bonds into carboxylic acids. Specifically, each double-bonded carbon forms a bond with an oxygen atom, resulting in the formation of carboxyl groups (-COOH) and hydroxyl groups (-OH). This process is essential for understanding lipid metabolism and the biochemical pathways involved in energy production through aerobic respiration.

How does the oxidation of triacylglycerols contribute to energy production in aerobic respiration?

The oxidation of triacylglycerols contributes to energy production in aerobic respiration by breaking down the triglyceride molecules into smaller units, specifically carboxylic acids. These carboxylic acids can then enter the citric acid cycle (Krebs cycle) and undergo further oxidation to produce ATP, the primary energy currency of the cell. This process is vital for cells to generate the energy needed for various metabolic activities, especially in tissues with high energy demands like muscles and the heart.

What are the products formed when triacylglycerols undergo oxidation?

When triacylglycerols undergo oxidation, the primary products formed are carboxylic acids. The elemental oxygen (O₂) cleaves the pi bonds in the double-bonded carbons of the triglyceride molecule, resulting in the formation of carboxyl groups (-COOH) and hydroxyl groups (-OH). This transformation is crucial for the subsequent metabolic processes that lead to energy production in the body.

Why is understanding the oxidation of triacylglycerols important in biochemistry?

Understanding the oxidation of triacylglycerols is important in biochemistry because it provides insights into lipid metabolism and energy production. This process is a key step in breaking down fats to produce ATP, which is essential for cellular functions. Additionally, it helps in understanding various metabolic pathways and the role of lipids in health and disease. Knowledge of this reaction is also crucial for developing strategies to manage metabolic disorders and improve overall metabolic health.

What happens to the double-bonded carbons in triacylglycerols during oxidation?

During the oxidation of triacylglycerols, the double-bonded carbons undergo cleavage by elemental oxygen (O₂). This cleavage results in the formation of carboxylic acids. Each double-bonded carbon forms a bond with an oxygen atom, creating carboxyl groups (-COOH) and hydroxyl groups (-OH). This transformation is essential for converting the triglyceride molecule into smaller, more metabolically active units that can be further processed for energy production.