Question

Identify the reagents underlined in the following equations as nucleophiles or electrophiles:
$C{H}_{3}COOH+\underset{―}{O{H}^{-}}\to C{H}_{3}CO{O}^{-}+H_{2}O$

Answer 1

Hint: Nucleophiles, just as its name suggests, are nucleus (proton) loving, as itself it is electron-rich. Whereas, the electrophiles are electron-deficient and are electron-loving in nature.

Complete step by step answer:
Nucleophiles are species which have either negative charge or have non-bonded lone pairs of electrons in them. So, being electron-rich, it has a tendency to share its electrons easily with other electron-deficient species forming a new covalent bond.
So, the nucleophilic species, with extra electrons having negative charge are called anions, whereas the neutral compounds have non-bonded lone pairs of electrons in them.
So, in the given reaction:
$C{H}_{3}COOH+\underset{―}{O{H}^{-}}\to C{H}_{3}CO{O}^{-}+H_{2}O$

The hydroxide ion, $O{H}^{-}$having a negative charge abstracts the proton from the weak acetic acid, and shares its electron with the proton forming a covalent bond in the water molecule formed.
Here, $O{H}^{-}$is a stronger nucleophile than the $C{H}_{3}CO{O}^{-}$. This is because nucleophile are often referred as bases (as they abstract protons), and $O{H}^{-}$ being the conjugate base of the weak acid (water) whereas, $C{H}_{3}CO{O}^{-}$ is the conjugate base of slightly more acidic (acetic acid) than water.

Therefore, the underlined reagent, $O{H}^{-}$is a nucleophile.

Note: The nucleophiles, in general, donate electrons to other species forming a shared bond-pair. Thus, are Lewis bases. Only, in the case of donating electrons to hydrogen, it can also be referred to as Bronsted base. The ease through which the nucleophile donates its electrons is known as its nucleophilicity, which depends on various factors such as charge, basicity, solvent, polarizability, and the nature of the substituents on it.