Chemistry - GOC Question with Solution | TestHub

Removing ${\mathrm{H}}_1$ (α to the ester carbonyl) gives an ester enolate :

Removing ${\mathrm{H}}_2$ gives an ordinary carbanion :

The enolate is resonance-stabilised, with most of the negative charge on the electronegative oxygen. The other anion is localised on carbon with no resonance. The α proton ${\mathrm{H}}_1$ is much more acidic.