A specialized hydride donor, Diisobutylaluminum hydride (DIBAL-H), is renowned for its specific chem — Redox Reactions and Volumetric Analysis Chemistry Question
Question
A specialized hydride donor, Diisobutylaluminum hydride (DIBAL-H), is renowned for its specific chemoselectivity. If an organic molecule containing both a nitrile ( $-C \equiv N$ ) group and a ketone ( $-C=O$ ) group is treated with exactly one equivalent of DIBAL-H at $-78^\circ C$ followed immediately by aqueous acidic hydrolysis, what is the primary structural outcome?
💡 Solution & Explanation
DIBAL-H at low cryogenic temperatures ( $-78^\circ C$ ) is highly specific. It acts as a bulky, electrophilic reducing agent, selectively attacking the electron-rich pi bonds of esters and nitriles to form a remarkably stable intermediate imine/aluminate complex. Upon acidic aqueous workup, this complex breaks down strictly to form an aldehyde. Ordinary ketones are structurally less reactive towards DIBAL-H at this specific low temperature compared to nitriles and esters.