Distinguish Between Chloroethane and Chlorobenzene

The easiest way to distinguish between chloroethane and chlorobenzene is by reacting both samples with KOH in the presence of an alcohol. Chloroethane forms an alkene upon reaction with KOH and an alcohol whereas chlorobenzene shows no reaction upon reaction with KOH and an alcohol.

We can perform this test because of the strength of the C-Cl bond in the chlorobenzene compound is greater than the strength of the C-Cl bond of the chloroethane molecule. Moreover, there are different chemical and physical properties between the two compounds. For example, chloroethane usually occurs as a flammable gas, whereas chlorobenzene compound usually occurs as a flammable liquid.

CONTENTS

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

What is Chloroethane?

Chloroethane or ethyl chloride is an organic compound with the chemical formula C₂H₅Cl. This compound has the structure of ethane with one of its hydrogen atoms replaced with a chlorine atom. Chloroethane occurs as colourless and flammable gas, and we can keep it in the liquid form when refrigerated. In addition to these, this compound is commonly used as a gasoline additive.

Moreover, its molar mass is 64.51 g/mol. It has a pungent and ethereal odour. The melting point is −138.7 °C, and the boiling point is 12.27 °C. Furthermore, we can produce this compound via hydrochlorination of ethane.

What is Chlorobenzene?

Chlorobenzene is an aromatic organic compound that has a benzene ring with an attached chlorine atom. The chemical formula of this compound is C₆H₅Cl. This compound occurs as a colourless and flammable liquid. However, it has an almond-like odour. The molar mass of chlorobenzene is 112.56 g/mol. The melting point of this compound is −45 °C while the boiling point is 131 °C. Further, when considering the uses of this compound, it is very important as an intermediate in the production of compounds such as herbicides, rubber, etc. Also, it is a high boiling solvent we use in industrial applications.

Moreover, we can produce chlorobenzene by chlorination of benzene in the presence of Lewis acids such as ferric chloride and sulfur dichloride. The Lewis acid acts as the catalyst of the reaction. It can enhance the electrophilicity of chlorine. Since chlorine is electronegative, chlorobenzene tends not to undergo further chlorination. More importantly, this compound shows low to moderate toxicity. However, if this compound enters our body via breathing, our lungs and urinary system can excrete it.

How to Distinguish Between Chloroethane and Chlorobenzene?

The easiest way to distinguish between chloroethane and chlorobenzene is the reaction of the sample with KOH in the presence of an alcohol. Therefore, the key difference between chloroethane and chlorobenzene is that chloroethane forms an alkene upon reaction with KOH and an alcohol whereas chlorobenzene shows no reaction upon reaction with KOH and an alcohol. We can perform this test because of the strength of the C-Cl bond in the chlorobenzene compound is greater than the strength of the C-Cl bond of the chloroethane molecule.

Moreover, chloroethane is an aliphatic organic compound, while chlorobenzene is an aromatic organic compound. In addition to these, another property we can look for to distinguish between chloroethane and chlorobenzene is that the chloroethane usually occurs as a flammable gas, whereas the chlorobenzene compound usually occurs as a flammable liquid.

Below infographic compares side by side the properties of the two compounds that would help to distinguish between chloroethane and chlorobenzene.

Summary – Chloroethane vs Chlorobenzene

Chloroethane is an aliphatic organic compound, while chlorobenzene is an aromatic organic compound. The easiest way to distinguish between chloroethane and chlorobenzene is by reacting both samples with KOH in the presence of an alcohol. Chloroethane forms an alkene whereas chlorobenzene shows no reaction upon reaction with KOH and an alcohol.

Reference:

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

Image Courtesy:

1. “Chloroethane-2D” By Maciejo93 – Own work (Public Domain) via Commons Wikimedia

2. “Mfcd00000530-medium (1)” By Yeckele – Own work (CC BY-SA 4.0) via Commons Wikimedia