Find most acidic hydrogen?
Identify familiar functional groups.
#p#is an amide proton. #"pK"_a ~~ 15# #Y#is an alkyl proton para to a carbonyl. #"pK"_a > 50# #X#is an alkyl proton adjacent to a carbonyl. #"pK"_a ~~ 20# #Z#is an amine proton. #"pK"_a > 30#
The most acidic hydrogens are (d) p.
Protons Y are alkane hydrogens. They are the least acidic.
Protons Z are amine hydrogens.
They are slightly more acidic than alkanes because
Protons X are alpha to a carbonyl group.
They are more acidic because the electrons of the conjugate base can be delocalized onto the adjacent carbonyl group to form a resonance-stabilized enolate ion.
Protons p are amide hydrogens.
The lone pair electrons can be delocalized onto the adjacent carbonyl group to form a resonance-stabilized anion.
Thus, protons p are the most acidic protons.