The increasing order of nucleophilicity of the following...

The increasing order of nucleophilicity of the following nucleophiles is: (i) $\mathrm{CH}_{3} \mathrm{CO}_{2}^{-}$ (ii) $\mathrm{H}_{2} \mathrm{O}$ (iii) $\mathrm{CH}_{3} \mathrm{SO}_{3}^{-}$ (iv) $\mathrm{OH}$ (a) $(\mathrm{i})<(\mathrm{iv})<(\mathrm{iii})<(\mathrm{ii})$ (b) $($ ii $)<($ iii $)<($ iv $)<($ i) (c) $(\mathrm{iv})<(\mathrm{i})<(\mathrm{iii})<(\mathrm{ii})$ (d) $($ ii $)<($ iii $)<($ i $)<$ (iv)

The increasing order of nucleophilicity of the following nucleophiles is:
(i) $\mathrm{CH}_{3} \mathrm{CO}_{2}^{-}$
(ii) $\mathrm{H}_{2} \mathrm{O}$
(iii) $\mathrm{CH}_{3} \mathrm{SO}_{3}^{-}$
(iv) $\mathrm{OH}$
(a) $(\mathrm{i})<(\mathrm{iv})<(\mathrm{iii})<(\mathrm{ii})$
(b) $($ ii $)<($ iii $)<($ iv $)<($ i)
(c) $(\mathrm{iv})<(\mathrm{i})<(\mathrm{iii})<(\mathrm{ii})$
(d) $($ ii $)<($ iii $)<($ i $)<$ (iv)

Key Concepts

Basicity

Basicity is the tendency of a species to accept a proton, which is related to the availability of its electron pairs. Although nucleophilicity and basicity are not identical, they are often correlated because both involve electron pair donation. In the example context, stronger bases, all else being equal, are typically better nucleophiles.

Nucleophilicity

Nucleophilicity refers to the ability of a species to donate an electron pair to an electrophile in a chemical reaction. It is a kinetic concept and depends on factors like charge, basicity, steric bulk, and the medium of the reaction. In comparing different nucleophiles, species with higher electron density (often associated with a negative charge) tend to be more nucleophilic.

Resonance Stabilization

Resonance stabilization occurs when a negative charge is delocalized across several atoms, reducing the electron density at any one point. This delocalization can lower the reactivity of a nucleophile because the charge is less available for bonding. Nucleophiles that are resonance-stabilized tend to be weaker compared to those where the charge is localized.

Solvation Effects

Solvation effects refer to the interaction between solvent molecules and the nucleophile. In polar protic solvents, small anions such as hydroxide are strongly solvated, which can impact their effective nucleophilicity by partially shielding the reactive site. The balance between solvation and the intrinsic electron density of the nucleophile influences its overall reactivity in a given medium.

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