RX where R is an alkyl groupMonohalogen derivatives of alkanes are called Haloalkanes or alkyl halides. They are formed by replacing one hydrogen atom in alkane.
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:
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:
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: