Reimer-Tiemann reaction introduces an aldehyde group, on to the aromatic ring of phenol, ortho to the hydroxyl group. This reaction involves electrophilic aromatic substitution. This is a general method for the synthesis of substituted salicyladehydes as depicted below.
Which one of the following reagents is used in the above reaction?
Which one of the following reagents is used in the above reaction?
- (A)aq.
- (B)aq.
- (C)aq. ✓ Correct
- (D)aq.
Answer: (C)
Solution
The Reimer-Tiemann reaction uses chloroform (CHCl₃) in the presence of aqueous NaOH. Under basic conditions, CHCl₃ loses a proton to form the trichloromethyl anion CCl₃⁻, which then loses a chloride ion to generate dichlorocarbene (:CCl₂), the reactive electrophile. This carbene attacks the activated aromatic ring of phenoxide ion ortho to the oxygen, ultimately forming salicylaldehyde after hydrolysis.
JEE Advanced · 2007 · 08 Apr 2007 · Paper 2 · Single correct option