See image — Aldehydes Ketones and Carboxylic Acids Chemistry Question

💡 Solution & Explanation

Concept: Stable gem-diol (hydrate) formation from carbonyl compounds is favored by strong electron-withdrawing groups (EWGs) attached to the carbonyl carbon. EWGs destabilize the carbonyl by reducing electron density, making the carbonyl carbon more electrophilic and shifting equilibrium toward the hydrate. Steric factors also play a role (less hindered carbonyls react more readily). Step 1 – Option (a) CCl3CHO (Chloral): Chlorol has three chlorine atoms (strong EWG via induction) attached to the carbon adjacent to the aldehyde carbonyl. This strongly withdraws electron density from the carbonyl carbon, making it highly electrophilic. The resulting gem-diol, CCl3CH(OH)2 (chloral hydrate), is well known to be isolable and stable. So (a) forms a stable hydrate. Step 2 – Option (b) Ninhydrin: Ninhydrin contains a ketone carbonyl (the central C=O of the five-membered ring) flanked by two other carbonyl groups (CO groups). These adjacent carbonyl groups act as powerful EWGs, greatly activating the central carbonyl toward nucleophilic addition by water. Ninhydrin is known to exist significantly as its hydrate form (ninhydrin hydrate). So (b) forms a stable hydrate. Step 3 – Option (c) (CF3)2CO (Hexafluoroacetone): Hexafluoroacetone has two trifluoromethyl groups (very strong EWGs) flanking the carbonyl. Despite being a ketone (which normally does not form stable hydrates due to steric and electronic reasons), the extreme electron-withdrawing effect of two CF3 groups makes the carbonyl carbon extremely electrophilic. Hexafluoroacetone is well known to form a very stable hydrate, (CF3)2C(OH)2. So (c) forms a stable hydrate. Step 4 – Why all three form stable hydrates: All three compounds bear strong electron-withdrawing substituents on or adjacent to the carbonyl carbon, which strongly favor nucleophilic addition of water and stabilize the resulting gem-diol relative to the carbonyl form. Step 5 – Conclusion: Since (a), (b), and (c) all form stable hydrates, the answer is (d) All of these. Therefore, the correct answer is D.