Oxidative cleavage of retinol's C=C bonds with acidified KMnO4

Steps:

• Acidified KMnO4 under hot, concentrated conditions oxidatively cleaves C=C bonds in alkenes like retinol.
• Cleavage of =CH- groups in retinol's conjugated system yields aldehyde fragments initially.
• =CR2 groups yield ketones, but retinol's structure emphasizes aldehyde intermediates.
• Further oxidation under these vigorous conditions converts aldehydes to carboxylic acids.

Why D is correct:

• Hot, concentrated acidified KMnO4 cleaves bonds to aldehydes (initial) and carboxylic acids (from further oxidation of aldehydic fragments), matching retinol's =CH- dominant double bonds per standard alkene oxidation rules.

Why the others are wrong:

• A: Cold, dilute gives vicinal diols, not bond cleavage or carbonyl products.
• B: Produces ketones from =CR2, but retinol cleavage prioritizes aldehydes over ketones in this context.
• C: Cold, dilute fails to cleave bonds, yielding only diols, not ketones or acids.

Final answer: D