Introduction, classification and isomerism of haloalkanes

The halogen derivatives of aliphatic and aromatic hydrocarbons are called haloalkanes and haloarenes. These are obtained when the hydrogen atom of an alkane and arene is replaced by a halogen atom (F, Cl, Br and I). Their general formulae are:

Haloalkane

RX where R is an alkyl group

Monohalogen derivatives of alkanes are called Haloalkanes or alkyl halides. They are formed by replacing one hydrogen atom in alkane.

Haloarene

ArX where Ar is arene.

'X' is halogen atom (F, Cl, Br, I)

Haloarenes or aryl halides are halogen derivatives of aromatic hydrocarbons, which are derived by replacing hydrogen atom attached to the benzene ring by a halogen atom. Therefore, in haloarenes, the halogen atom (F, Cl, Br or I) is directly attached to the aromatic ring. For example,

Isomerism in Haloalkanes

Isomerism in haloalkanes is of two types:

Chain isomerism

Haloalkanes containing four or more carbon atoms exhibit chain isomerism in which the isomers differ in the chain of carbon atoms. For example, C₄H₉Br has three chain isomers, such as:

Position isomerism

Haloalkanes with three or more carbon atoms exhibit position isomerism in which the isomers differ in the position of halogen atom. For example, C₃H₇I has two position isomers: