Question

Arrange the following anions according to the increasing order of their stability.

(I) \[\ce{\underset{Alkoxide anion}{R - O^-}}\]

(II)

Phenoxide anion

(III) \[\begin{array}{cc}
\ce{O}\phantom{..}\\
||\phantom{..}\\
\ce{\underset{Carboxylate anion}{R - C - O^-}}\\
\end{array}\]

Options

• II > III > I

• I > II > III

• III > II > I

• I > III > II

Answer 1

III > II > I

Explanation:

Resonance stabilises both phenoxide and carboxylate anions. Because the negative charge is delocalized on two electronegative O atoms, the carboxylate ion is more stable than the phenoxide ion.