Chemistry - STRUCTURAL ISOMERISM Question with Solution | TestHub

Under $\mathrm{O}{\mathrm{D}}^{-}/{\mathrm{D}}_2\mathrm{O}$ only the alpha C-H protons of the two carbonyls exchange. The alpha positions are : the $\mathrm{C}{\mathrm{H}}_2$ between the two $\mathrm{C}=\mathrm{O}$ groups (2H, doubly activated), and the two outer $\mathrm{C}{\mathrm{H}}_2$ groups alpha to one carbonyl each (2H + 2H). The gem-dimethyl group is not alpha to any carbonyl, so its 6 methyl hydrogens stay in place. Total : 6 hydrogens exchanged.