91Ó°ÊÓ

The base donates a lone pair of electrons to the most acidic hydrogen atom in the acid leading to its deprotonation. The proton is transferred from the acid to the base.

Among the different groups present in the compounds, the more acidic hydrogen atom is the one that can easily dissociate from the acid and which is attached to the most electronegative group.

A more acidic proton is transferred to the base in each reaction.

a. The most acidic hydrogen is present in the –COOH group. Hence, the protonation takes place from the group –COOH.

Acid-base reaction in a.

b. The ease of donating the electron pair depends upon the electronegativity and steric hindrance in this compound.

Out of the three groups having lone pairs of electrons, i.e., fluorine, oxygen, and nitrogen, nitrogen is the least electronegative element and hence can leave an electron pair at ease compared to the oxygen and fluorine atom.

Hence, in this case, nitrogen is the donor atom.

Acid-base reaction in b.