Difference Between Ether and Petroleum Ether

The key difference between ether and petroleum ether is that ether is an organic compound with a –O- ether linkage while petroleum ether is a mixture of hydrocarbon compounds.

Most people find the terms ether and petroleum ether confusing because of the similarity in names. Though their names are bit similar and both are liquids, they are completely different chemicals and have different uses. Thus, this article explores the difference between ether and petroleum ether.

CONTENTS

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

What is Ether?

An ether is an organic molecule which has an oxygen atom bound to two carbon atoms in two sides. Therefore, ether is a type of organic molecule in which two alkyl groups, aryl groups, or an alkyl and an aryl group, are connected to both sides of an oxygen atom. Depending on the R groups, there are two types of ethers as symmetrical and unsymmetrical ethers. If both R groups are similar, then the molecule is symmetrical; if both are different, it is unsymmetrical.  For example, dimethylether is the simplest ether with the formula CH3-O-CH3. It is a symmetrical molecule.

Furthermore, the oxygen atom in ether has sp3 hybridization. Among the four electron pairs, two lone pairs are in two hybridized orbitals while the other two electron pairs participate in bonding with R groups. R-O-R bond angle is about 104.5°, which is similar to water. Moreover, the boiling points of ethers are roughly comparable with those of hydrocarbons with the same molecular weight, but are lower than that of alcohols. Besides, though ethers cannot make hydrogen bonds within them, they are able to form hydrogen bonds with other compounds such as water. Therefore, this compound is soluble in water. But, the solubility may decrease depending on the length of the hydrocarbon chains attached.

In case of dialkyl ethers, they react with very few reagents other than acids. The reactive sites are the C-H bonds of the alkyl groups and the –o- group of the ether linkage.

Figure 1: General Structure of Ether Molecule

Production of  Ether

We can produce an ether via intermolecular dehydration of alcohols. It usually takes place at a lower temperature than dehydration to the alkene. Furthermore, Williamson synthesis is another method to produce unsymmetrical ethers. The synthesis takes place between a sodium alkoxide and an alkyl halide, alkyl sulfonate or alkyl sulfate.

What is Petroleum Ether?

Petroleum ether is a mixture of hydrocarbon compounds. Though its name says ether, it doesn’t have compounds with ether linkages. It is formed during the petroleum refining process. Furthermore, it is a highly flammable and volatile liquid and is colorless. Also, it is a nonpolar solvent.

Figure 2: A Bottle of Petroleum Ether

The boiling point of this compound is 60 oC. Its specific gravity is 0.7, which is less than that of water. This compound is also known as benzine or ligroin. Petroleum ether is mainly important in the laboratory as a solvent.

What is the Difference Between Ether and Petroleum Ether?

Ether is an organic molecule containing carbon, hydrogen and oxygen atoms while petroleum ether is a mixture of hydrocarbons. Therefore, the key difference between ether and petroleum ether is that ether is an organic compound with a –O- ether linkage, while petroleum ether is a mixture of hydrocarbon compounds. Moreover, ether molecules essentially contain ether linkage, whereas petroleum ether does not contain such linkages at all.

Furthermore, there is a difference between ether and petroleum ether in their production too. Petroleum ether is a product from the petroleum refining process, but ether is produced via intermolecular dehydration of alcohols. When considering the water solubility, some ether molecules can form hydrogen bonds with water molecules and are water soluble whereas petroleum ether never forms hydrogen bonds, and are water insoluble. So, this is also a difference between ether and petroleum ether.

Summary – Ether vs Petroleum Ether

Ether and petroleum ether have closely related names, but they are completely different in chemical composition and properties. The key difference between ether and petroleum ether is that ether is an organic compound with a –O- ether linkage, while petroleum ether is a mixture of hydrocarbon compounds.

Reference:

1 “18.1: Names and Properties of Ethers.” Chemistry LibreTexts, Libretexts, 23 May 2019, Available here.
2. “Petroleum Ether.” Wikipedia, Wikimedia Foundation, 19 Feb. 2019, Available here.

Image Courtesy

1. “Ether-(general)” By Benjah-bmm27 assumed -Own work assumed (based on copyright claims) (Public Domain) via Commons Wikimedia
2. “Petroleum ether” By Seilvorbau – Own work (CC BY-SA 4.0) via Commons Wikimedia

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