JEE Main 2022 · 29 Jul · Shift 1 · Chemistry Q72

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ChemistrySingle correct+4 / -1Question 72 of 90

Which among the following is the strongest Bronsted base ?

Triethylamine, (CH₃CH₂)₃N

Option A: triethylamine, N bonded to three ethyl groups.

Diethylamine, (CH₃CH₂)₂NH

Option B: diethylamine, N bonded to two ethyl groups and H.

1-Methyl-2-pyrroline (N-methyl ring enamine)

Option C: five-membered ring with N-CH3 and a C=C double bond next to N (1-methyl-2-pyrroline).

Quinuclidine (1-azabicyclo[2.2.2]octane)

Option D: quinuclidine, a bicyclic amine with N at a bridgehead and its lone pair pointing outward.

Answer and worked solution

Official answer: D

Lone pair availability. Quinuclidine's N is tied back in a cage, so its lone pair is fully exposed and protonation is not hindered (pKₐH about 11.0). Triethylamine's ethyl groups crowd the cation's solvation, the enamine N lone pair is delocalised into the C=C, and diethylamine is slightly weaker.

(D)

Topics:Acidity and basicity Amines

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JEE Main 2022 · 29 Jul · Shift 1, Chemistry question 72