Difference Between Oleic Acid and Elaidic Acid

The key difference between oleic acid and elaidic acid is that oleic acid occurs in the liquid phase, whereas elaidic acid occurs in the solid form.

Oleic acid and elaidic acid are organic compounds. These are acidic compounds containing carboxylic acid groups at the end of a carbon chain. Both these are unsaturated fatty acids because they have a double bond at the middle of the carbon chain. Oleic acid and elaidic acid are cis-trans isomers of each other.

1. Overview and Key Difference
2. What is Oleic Acid
3. What is Elaidic Acid
4. Side by Side Comparison – Oleic Acid vs Elaidic Acid in Tabular Form
5. Summary

What is Oleic Acid?

Oleic acid is the cis isomer of the fatty acid, having the chemical formula C₁₈H₃₄O₂. It is the cis isomer of elaidic acid. This substance occurs as an oily liquid that is colourless and odourless. However, commercially available samples of oleic acid can be yellowish. We can classify oleic acid as a monounsaturated omega-9 fatty acid. The molar mass of this compound is 282.046 g/mol. It has a low melting point (13 Celsius) and a comparatively a high boiling point (360 Celsius). This substance is insoluble in water, and it is soluble in organic solvents such as ethanol.

The name of this substance comes from the Latin word “oleum”, which means oil or oily. Oleic acid is the most common naturally occurring fatty acid. There are salts and esters of oleic acid named collectively as oleates. Often, we can find oleic acid in its ester form rather than in biological systems. This compound commonly occurs in the form of triglyceride. Common compounds containing oleic acid components include phospholipids in cell membranes, cholesterol esters, wax esters, etc.

Oleic acid forms via biosynthesis, which involves the enzymatic activity of stearoyl-CoA9-desaturase acting on stearoyl-CoA. Here, stearic acid is dehydrogenated to form monounsaturated derivative, oleic acid.

What is Elaidic Acid?

Elaidic acid is the trans isomer of the fatty acid having the chemical formula C₁₈H₃₄O₂. It is the trans isomer of oleic acid. It is a monounsaturated fatty acid containing a carboxylic acid group. It occurs as a colourless, odourless oily solid. The melting point of this compound is relatively high (about 45 Celsius).

Elaidic acid is commonly known because it is the major trans fat that we can find in hydrogenated vegetable oils, so these are the trans fats that play a major role in heart diseases formation. The salts and esters of elaidic acid are collectively named as elaidates.

We can find elaidic acid in trace amounts in caprine and bovine milk. It also occurs in some meats. In addition, it is a constituent in the fruit Durian. Elaidic acid is known to be helpful in increasing the plasma cholesterylester transfer protein activity. This compound is important in lowering HDL cholesterol.

What is the Difference Between Oleic Acid and Elaidic Acid?

Oleic acid and elaidic acid are cis-trans isomers of each other. The key difference between oleic acid and elaidic acid is that oleic acid occurs in the liquid phase, whereas elaidic acid occurs in the solid form.

Moreover, oleic acid is the cis isomer of elaidic acid. The salts and esters of oleic acid are called oleates while the salts and esters of elaidic acid are named as elaidates.

Below infographic summarizes the difference between oleic acid and elaidic acid.

Summary – Oleic Acid vs Elaidic Acid

Oleic acid and elaidic acid are organic compounds. These are acidic compounds containing carboxylic acid groups at the end of a carbon chain. Oleic acid and elaidic acid are cis-trans isomers of each other. The key difference between oleic acid and elaidic acid is that oleic acid occurs in the liquid phase, whereas elaidic acid occurs in the solid form.

Reference:

1. “Oleic Acid.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.

Image Courtesy:

1. “Oleic-acid-skeletal” (Public Domain) via Commons Wikimedia
2. “Elaidic-acid-2D-skeletal-reverse” By Ben Mills – Own work (Public Domain) via Commons Wikimedia