Question

Rank the compounds in each group according to their reactivity toward electrophilic substitution. 1 = most reactive; 3 = least reactive.

a. benzaldehyde p-methylbenzaldehyde p-chlorobenzaldehyde

b. chlorobenzene o-dichlorobenzene benzene

Answer 1

a. benzaldehyde (2), p-methylbenzaldehyde (1), p-chlorobenzaldehyde (3)

b. chlorobenzene (2), o-dichlorobenzene (3), benzene (1)

Step-by-step explanation:

a. Based on inductive effect, p-chlorobenzaldehyde (3) is the least reactive, benzaldehyde (2) is less reactive while p-methylbenzaldehyde (1) is the most reactive.

b. Based on the location of either meta, ortho and para on the benzene ring, benzene is the most reactive (1), chlorobenzene is less reactive (2), o-dichlorobenzene (3) is the least reactive.