Arrange the following compounds in increasing order of rate of aromatic electrophilic substitution reaction
(a) (see structure)
(b) (see structure)
(c) (see structure)
(d) (see structure)
(a) (see structure)
(b) (see structure)
(c) (see structure)
(d) (see structure)
- (A)d, b, c, a
a 
b 
c 
d - (B)b, c, a, d
- (C)c, a, b, d✓ Correct
- (D)d, b, a, c
Answer: (C)
Solution
The rate of aromatic electrophilic substitution rises with the electron density of the ring. In (c), an -tetralone, a carbonyl group is conjugated to the ring and withdraws electrons by resonance and induction, making it least reactive. In (a) only saturated carbons are attached to the ring, giving weak activation. In (b) a phenolic is bonded directly to the ring, a strong donor. In (d) the ring carries both a phenolic and a ring ether oxygen, two strong donors, making it the most reactive. The increasing order of rate is therefore c < a < b < d.
JEE Main · 2023 · 11 Apr 2023 · Shift 1 · Single correct option