Question

In the following pair of compounds, which of the following relation is correct for nucleophilicity in a polar-protic solvent?

• A. ${CH}_{3}S{CH}_3>{CH}_{3}O{CH}_3$
• B. ${CH}_{3}S{CH}_3<{CH}_{3}O{CH}_3$
• C. ${CH}_{3}S{CH}_3={CH}_{3}O{CH}_3$
• D. None of these

Answer 1

The correct option is A ${CH}_{3}S{CH}_3>{CH}_{3}O{CH}_3$

In a polar-protic solvent, the order of nucleophilicity is ${CH}_{3}S{CH}_3>{CH}_{3}O{CH}_3$
as $O$ is more electronegative than $S$. Hence, the lone pair of electrons is more strongly held by $O$ than by $S$.
Hence, it cannot be easily donated by $O$.
Hence, dimethyl ether is less nucleophilic than dimethyl sulphide.