Difference Between Chlorobenzene and Benzyl Chloride

Main Difference – Chlorobenzene vs Benzyl Chloride

Although the names Chlorobenzene and benzyl chloride are confusing, they are two terms used to name two different compounds. Both of them are aromatic compounds because they contain benzene rings substituted with different substituents. They have different chemical and physical properties as discussed below. The main difference between Chlorobenzene and Benzyl Chloride is that chlorobenzene has a chlorine atom directly attached to the benzene ring whereas benzyl chloride has a chlorine atom indirectly attached to the benzene ring (attached via a -CH2 group).

Key Areas Covered

1. What is Chlorobenzene
     – Definition, Chemical Properties, Uses
2. What is Benzyl Chloride
     – Definition, Chemical Properties, Uses
3. What is the Difference Between Chlorobenzene and Benzyl Chloride
     – Comparison of Key Differences

Key Terms: Aromatic, Benzene, Benzyl Chloride, Boiling Point, Chlorobenzene, Chloromethylbenzene, Melting Point, Molar Mass

What is Chlorobenzene

Chlorobenzene is an organic compound having the chemical formula C₆H₅Cl. It is derived from a benzene ring by replacing one hydrogen atom with a chlorine atom. It is an aromatic compound. At room temperature, Chlorobenzene is a colorless, flammable liquid. The common name used for Chlorobenzene is benzene chloride.

Figure 1: Chemical Structure of Chlorobenzene

The molar mass of Chlorobenzene is 112.56 g/mol. It has an almond-like odor. The melting point of Chlorobenzene is −45 °C, and the boiling point is 131 °C. This compound is soluble in most organic solvents. But it is insoluble in water. Chlorobenzene vapor is heavier than normal air.

Chlorobenzene is used as an intermediate in the production of herbicides, pesticides, rubber, etc. It is also used as a high boiling solvent in different industries due to the high boiling point. However, Chlorobenzene shows low-to-moderate toxicity.

What is Benzyl Chloride

Benzyl chloride is an aromatic organic compound having the chemical formula C₇H₇Cl. It is derived from a toluene by replacing a hydrogen atom of a methyl group with a chlorine atom. At room temperature, it is a colorless (slightly yellow) liquid with a pungent odor. It is called benzyl chloride due to the presence of a benzyl group.

Figure 2: Chemical Structure of Benzyl Chloride

The molar mass of benzyl chloride is 126.58 g/mol. The melting point of benzyl chloride is −39 °C and the boiling point is 179 °C. It is very slightly soluble in water but is well dissolved in organic solvents. The IUPAC name of benzyl chloride is chloromethylbenzene.

Benzyl chloride is mainly produced by the photochemical reaction between toluene and chlorine gas. Here, HCl is formed as a byproduct. The reaction is a free radical process. Benzyl chloride is a precursor for the production of benzyl esters and benzyl ethers. In addition, this compound can be used to make Grignard reagent by reaction between benzyl chloride and metallic magnesium.

Difference Between Chlorobenzene and Benzyl Chloride

Definition

Chlorobenzene: Chlorobenzene is an organic compound having the chemical formula C₆H₅Cl.

Benzyl Chloride: Benzyl chloride is an aromatic organic compound having the chemical formula C₇H₇Cl.

Position of the Chlorine Atom

Chlorobenzene: Chlorobenzene has a chlorine atom directly attached to the benzene ring.

Benzyl Chloride: Benzyl chloride has a chlorine atom indirectly attached to the benzene ring (attached via a -CH2 group).

Molar Mass

Chlorobenzene: The molar mass of Chlorobenzene is 112.56 g/mol.

Benzyl Chloride: The molar mass of benzyl chloride is 126.58 g/mol.

Melting and Boiling Point

Chlorobenzene: The melting point of Chlorobenzene is −45 °C, and the boiling point is 131 °C.

Benzyl Chloride: The melting point of benzyl chloride is −39 °C, and the boiling point is 179 °C.

Odor

Chlorobenzene: Chlorobenzene has an almond-like odor.

Benzyl Chloride: Benzyl chloride has a pungent odor.

Water Solubility

Chlorobenzene: Chlorobenzene is not water soluble.

Benzyl Chloride: Benzyl chloride is very slightly water soluble.

Conclusion

Chlorobenzene and benzyl chloride are two aromatic organic compounds containing benzene rings in their chemical structure. The main difference between Chlorobenzene and benzyl chloride is that chlorobenzene has a chlorine atom directly attached to the benzene ring whereas benzyl chloride has a chlorine atom indirectly attached to the benzene ring (attached via a -CH2 group).

Reference:

1. “CHLOROBENZENE.” National Center for Biotechnology Information. PubChem Compound Database, U.S. National Library of Medicine, Available here.
2. “Benzyl chloride.” Wikipedia, Wikimedia Foundation, 5 Jan. 2018, Available here.

Image Courtesy:

1. “Chlorobenzene 200” By Emeldir (talk) – Own work (Public Domain) via Commons Wikimedia
2. “Benzyl chloride” By User:Bryan Derksen – Own work (Public Domain) via Commons Wikimedia