Question

Rank the compounds below in order of decreasing reactivity towards electrophilic aromatic substitution. Most reactive Least reactive COOH H3C CH3 COOH HaC

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Answer 1

Answer COOH COOH OOH 1 is electron rich due to electron donating group present on the ring, it is more reactive towards electrophilic substution then 2 is having donating (CH3) group and withdrawing (COOH) group 3 structure is least reactive towards electrophilic substution Br HNMR: 7.7 (m, 2H, ortho proton) 7.2 (m, 2H, meta proton) 7.7 Br 7.7 1,2-dibromobenzene C13: 3 peaks 7.2 Br IR: 745 broad singlet indicates ortho disubstuted benzene Br HN H Most resonance hybrid structure C Fourth resonance structure is Br