4. From Phenol
Physical Properties of Aryl Halides
1. Aryl halides are colourless liquids or colourless solids with characteristic odour.
2. Boiling point generally increases with increase in the size of aryl group or halogen atom. Boiling point order
Ar – I > Ar – Br > Ar – Cl > Ar – F
3. The melting point of p-isomer is more than 0- and m-isomer. This is because of more
symmetrical nature of p-isomer.
4. Due to resonance in chlorobenzene, C-CI bond is shorter and hence, its dipole moment is less than that ofcyclohexylchloride.
Chemical Properties of Aryl Halides
1. Nucleophilic Substitution Reaction
Aryl halides are less reactive towards nucleophilic substitution reaction. Their low reactivity is attributed due to the following reasons:
1. Due to resonance, C-X bond has partial double bond character. 2. Stabilisation of the molecule by delocalisation of electrons. 3.( Instability of phenyl carbocation.