Question

Consider thiol anion $\left(R{S}^{\ominus }\right)$ and alkoxy anion $\left(R{O}^{\ominus }\right)$. Which of the following statements is correct?

• A. $R{S}^{\ominus }$ is less basic but more nucleophilic than $R{O}^{\ominus }.$
• B. $R{S}^{\ominus }$ is more basic and more nucleophilic than $R{O}^{\ominus }$.
• C. $R{S}^{\ominus }$ is more basic but less nucleophilic than $R{O}^{\ominus }$.
• D. $R{S}^{\ominus }$ is less basic and less nucleophilic than $R{O}^{\ominus }$.

Answer 1

Answer: (A)

$R{S}^{\ominus }$ is more nucleophilic than $R-O^{\ominus }$ due to larger size of orbitals and polarization but $R{S}^{\ominus }$ is less basic than $R-O^{\ominus }$ as the negative charge get stabilized due to larger size of sulphur atom.