JEE Main 2026 · 2 Apr · Shift 1 · Chemistry Q68

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ChemistrySingle correct+4 / -1Question 68 of 75

Consider the three aromatic molecules (P, Q and R) whose structures have been given below :

The correct order regarding the reactivity of these compounds with $\ce{Ph-\overset{(+)}{N}#N\,Cl^{(-)}}$ under optimum but slightly acidic medium is :

Q: N,N,2-trimethylaniline (NMe₂ with one ortho methyl group).

R: N,N,2,6-tetramethylaniline (NMe₂ flanked by two ortho methyl groups).

P > Q > R

R > P > Q

R > Q > P

P > R > Q

Answer and worked solution

Official answer: A

Azo coupling is an electrophilic substitution para to $\ce{-NMe2}$ , which works only while the N lone pair is conjugated with the ring.

Steric inhibition of resonance. Ortho methyl groups twist $\ce{NMe2}$ out of the ring plane:

one ortho Me (Q) reduces activation;
two (R) almost removes it.

Order P > Q > R.

(A)

Topics:Diazonium salts Electronic effects (inductive, resonance, hyperconjugation)

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JEE Main 2026 · 2 Apr · Shift 1, Chemistry question 68