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 .