(a) Define the following terms:
(i) Enantiomers
(ii) Racemic mixture
(b) Why is chlorobenzene resistant to nucleophilic substitution reaction?
(a) (i) Enantiomers are the steroisomers that forms non - superimposable mirror images.
eg.
(ii) Racemic mixture is a mixture of equal amount of left and right handed enantiomer of a chiral carbon.
(b) In chlorobenzene, the lone pair of electrons of chlorine is delocallised over the benzene to form resonating structures.
Hence, a double bond character is developed between C and Cl making it difficult to breal C - Cl bond hence nucleohillic substitution becomes difficult.