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Payal posted an Question

January 30, 2021 • 18:48 pm

30 points

IIT JAM
Chemistry (CY)

Q7. which of the following is the strongest base in water? a) b) ) d)

Q7. Which of the following is the strongest base in water? a) b) ) d)

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Amol ashok pawar

Option D As in a the lone pair of nitrogen takes part in resonance Inc the nitrogen is sp2 hance more acidic characters In b the ring size is smaller than D so i D is stronger base by sp3 and ring size in water
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Priyanshu kumar Best Answer

option B pyrrolidine is slightly more basic than piperidine Pyrrolidine is a fully reduced pyrrole and piperidine is a fully reduced pyridine. Now pyrrolidine has a five membered ring while piperidine has a six membered ring. Apparently pyrrolidine gains a touch more conformational stabilization after protonation due to its five membered ring and we know that a five membered ring is more stable than a six membered ring. Hence the conjugate acid of pyrrolidine is slightly more stabilized over piperidine and hence pyrrolidine has a slightly higher basicity over piperidine
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option A pyrrole is least basic as lone pair on the nitrogen is a part of aromatic ring...so not available for donation
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The nitrogen in pyridine is sp2 hybridized while in piperidine its sp3 hybridized. Sp2 centres are electron withdrawing centres so they attract the lone pair and not let it go. While in piperidine the nitrogen is sp3 where no attraction is working and hence, it easily gives its lone pair. Basicity is the degree to which the atom can donate lone pair. So more donating, more basic; less donating, less basic. Hence, pyridine is less basic than piperidine.
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overall basicity order b>d>c>a
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