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Why is allyl chloride classified as an alkyl halide despite having a carbon-carbon double bond?

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organohalogen compound Vinyl chloride is an organohalogen compound that has important industrial applications. When treated with certain catalysts, vinyl chloride monomers undergo polymerization and form the larger compound known as polyvinyl chloride, or PVC. PVC is used in the manufacture of numerous products, including packaging films and water pipes.

Allyl chloride is classified as an alkyl halide because the classification of an organohalogen compound is determined specifically by the type of carbon atom to which the halogen is directly bonded, rather than the presence of other functional groups elsewhere in the molecule.1

In the case of allyl chloride ( ${CH}_{2} = {CHCH}_{2} Cl$ ), the carbon atom that bears the chlorine atom is involved only in single bonds with its attached atoms. Because this specific carbon atom does not participate in a double bond, the molecule meets the criteria for an alkyl halide, even though a double bond exists elsewhere in the carbon chain. This same principle applies to other compounds, such as benzyl chloride, which is also categorized as an alkyl halide despite the presence of an aromatic ring.1