Chemistry - GOC Question with Solution | TestHub
ChemistryGOCAcid BaseHard2 minQB
ChemistryHardinteger
Passage / Comprehension
Paragraph for Questions 20 and 21
Adenine is a heterocyclic compound with five nitrogen atoms, numbered (1) to (5) as shown below :
Which nitrogen (give its number from 1 to 5) is the most basic site towards protonation ?
Answer:
4
Solution:
Only the localised lone pairs on (2), (3) and (4) are available for protonation; (1) and (5) are delocalised.
Protonation on (4) gives a cation which is stabilised by resonance with the amino group (5): the charge is shared between nitrogen (4) and nitrogen (5) through the amidine-type system N(5)–C=N(4). Protonation on (2) or (3) gives no such extra stabilisation.
So nitrogen (4) is the most basic.
Answer: 4.
Stream:JEESubject:ChemistryTopic:GOCSubtopic:Acid Base
⏱ 2mℹ️ Source: QB
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