Which of the following reactions is an example of nucleophilic substitution reaction?
- 2RX + 2Na R-R + 2NaX
- RX + H2 RH + HX
- RX + Mg RMgX
- RX + KOH ROH + KX
Answer
(4) RX + KOH ROH + KX
Solution
(1) Wurtz reaction – coupling of two alkyl groups by sodium, not a substitution by a nucleophile.
(2) Reduction (hydrogenolysis) of the C–X bond.
(3) Formation of Grignard reagent – Mg is inserted between R and X.
(4) As per NCERT, the nucleophile OH- attacks the carbon of the C–X bond and the halide ion leaves:
R-X + OH- R-OH + X- nucleophilic substitution.
Answer: (4)