91Ó°ÊÓ

When a nucleophile adds to the carbonyl carbon of a carboxylic acid derivative, the weakest bond in the molecule—the p bond—breaks, and an intermediate is formed. It is called a tetrahedral intermediate because the ${\mathbf{sp}}^2$carbon in the reactant becomes a${\mathbf{sp}}^3$carbon (that is, a tetrahedral carbon) in the intermediate.

a.

HCl is a stronger acid than ${\mathrm{H}}_2\mathrm{O}$. So, ${\mathrm{Cl}}^{−}$is a weaker base than ${\mathrm{OH}}^{−}$. Therefore, ${\mathrm{Cl}}^{−}$will be eliminated from the tetrahedral intermediate. So, the product will be acetic acid represented as follows:

Formation of acetic acid

b.

${\mathrm{H}}_2\mathrm{O}$is stronger acid than ${\mathrm{NH}}_3$. So, ${\mathrm{OH}}^{−}$is weaker base than ${\mathrm{NH}}_2^{−}$. Therefore, ${\mathrm{OH}}^{−}$cannot eliminate the$−{\mathrm{NH}}_2$ group, so no reaction will occur which is represented as follows:

No products formed