Difference Between Sodium Stearate and Sodium Oleate

The key difference between sodium stearate and sodium oleate is that sodium stearate is the sodium salt of stearic acid, whereas sodium oleate is the sodium salt of oleic acid.

Sodium stearate and sodium oleate are sodium salts of two different acidic compounds. This means these compounds contain sodium as a cation and the conjugate base of acid compounds as anions. They have different chemical and physical properties due to different structures.

CONTENTS

1. Overview and Key Difference
2. What is Sodium Stearate
3. What is Sodium Oleate
4. Side by Side Comparison – Sodium Stearate vs Sodium Oleate in Tabular Form
5. Summary

What is Sodium Stearate?

Sodium stearate is an organic compound having the chemical formula C18H35NaO2. It is the sodium salt of stearic acid. Therefore, this compound contains a sodium cation in association with the conjugate base of static acid (the conjugate base is the stearate anion). It appears as a white solid when prepared. It has a slight, tallow-like odour as well. In its white solid form, sodium stearate is a common soap. Also, we can find this compound in many different types of deodorants, rubber, latex paint, and inks. Sometimes, sodium stearate is useful as a food additive for food flavouring.

Figure 01: The Chemical Structure of Sodium Stearate

Sodium stearate molecule has both hydrophilic and hydrophobic parts in the same molecule. This is a characteristic feature of soaps. Apart from that, it has a carboxylate group and a long hydrocarbon chain. The hydrophobic and hydrophilic parts in this molecule induce the formation of micelle when added to water. The hydrophilic heads form the outer sphere of the micelle and hydrophobic tails form the inner sphere of the micelle. Sodium stearate is useful in the pharmaceutical industry as a surfactant.

Sodium stearate production is done mainly via saponification of oils and fats. The amount of sodium stearate produced during this production method depends on the amount of fat used as the reactants. E.g. tallow is high in fat.

What is Sodium Oleate?

Sodium oleate is an organic compound having the chemical formula C18H33NaO2. This compound appears as a light tan solid at room temperature. It has a slight tallow-like odour. Sodium oleate is the sodium salt of oleic acid. Therefore, this molecule contains a sodium cation and the conjugate base of oleic acid; oleate anion. This compound can mix with water slowly.

Figure 02: The Chemical Structure of Sodium Oleate

Sodium oleate has a double bond at the middle of its long carbon chain. Therefore, this compound shows cis-trans geometry. The molecule also contains a carboxylic acid group, which makes the molecule hydrophilic and long carbon chain makes the compound hydrophobic. In aqueous solutions, this compound forms a slightly alkaline pH upon dissolution. In the food industry, sodium oleate is used as a stabilizer or as a thickener.

What is the Difference Between Sodium Stearate and Sodium Oleate?

Sodium stearate is an organic compound having the chemical formula C18H35NaO2 while sodium oleate is an organic compound having the chemical formula C18H33NaO2. The key difference between sodium stearate and sodium oleate is that sodium stearate is the sodium salt of stearic acid, whereas sodium oleate is the sodium salt of oleic acid. Furthermore, sodium stearate is a white solid while sodium oleate is a slightly tan solid.

Below infographic tabulates the differences between sodium stearate and sodium oleate.

Summary – Sodium Stearate vs Sodium Oleate

Sodium stearate and sodium oleate are sodium salts of two different acid compounds. The key difference between sodium stearate and sodium oleate is that sodium stearate is the sodium salt of stearic acid, whereas sodium oleate is the sodium salt of oleic acid.

Reference:

1. “Sodium Stearate.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Sodium Stearate.” Wikipedia, Wikimedia Foundation, 24 Apr. 2020, Available here.

Image Courtesy:

1. “Stearic Acid Sodium Salt Structural Formula V.2” By Jü – Own work (CC0) via Commons Wikimedia

2. “Sodium oleate” By Claudio Pistilli – Own work (CC BY-SA 4.0) via Commons Wikimedia

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