Which of the following statements is not correct?

see full answer

Your Exam Success, Personally Taken Care Of

1:1 expert mentors customize learning to your strength and weaknesses – so you score higher in school , IIT JEE and NEET entrance exams.

An Intiative by Sri Chaitanya

In electrophilic aromatic substitution reaction, the formation of intermediate arenium cation is the ratedetermining step.

The $C - H$ bond in benzene is slightly stronger than the $C - D$ bond in deuterated benzene ( $C_{6} D_{6}$ ).

The overall rate of an electrophilic substitution reaction, except sulphonation in benzene and deuterated benzene, are identical

answer is B.

(Unlock A.I Detailed Solution for FREE)

Best Courses for You

JEE

NEET

Foundation JEE

Foundation NEET

CBSE

Detailed Solution

(a) The formation of intermediate arenium cation is slow while the elimination of $H^{+}$ from this cation is fast. The former involves the removal of aromaticity while the latter restores aromaticity

(b) The $C - D$ bonds are stronger than $C - H$ bonds. In fact, the bond with the heavier isotope is slightly stronger than that with the lighter isotope.

( c) In electrophilic substitution reactions, the rate-determining step is the formation of arenium cation. Question Image

In this step, $E^{+}$ bonds to the aromatic ring without cleavage of a $C - H$ bond. The latter is broken in the second step, which is fast as it restores the stable aromatic system. Since $C - H$ or $C - D$ bond is not broken in the rate-determining step, the overall rates of reaction are identical.

Watch 3-min video & get full concept clarity