Classification

Haloalkanes and haloarenes are hydrocarbon derivatives in which one or more hydrogen atoms have been replaced by a halogen atom (F, Cl, Br or I), commonly written as X. Because this single family covers such a wide range of structures, it helps to sort them using two independent criteria before looking at any individual compound in detail.

Basis of Classification

By the number of halogen atoms present. A compound may carry one, two, or several halogen atoms in its structure, giving mono-, di-, and polyhalogen (tri-, tetra-, and so on) compounds.

By the hybridisation of the carbon atom bonded to the halogen. The halogen may sit on an $sp^3$-hybridised carbon or on an $sp^2$-hybridised carbon, and within the $sp^3$ case the position of that carbon relative to a double bond or an aromatic ring matters as well. This hybridisation-based split is really only meaningful for monohalogen compounds, since it looks at a single C—X bond at a time. …