nitronate

Nitronate refers to the conjugate base of a nitroalkane, formed by deprotonation at the carbon atom adjacent to the nitro group. The resulting nitronate anion is typically written as R-CH(-)-NO2 and is stabilized by resonance with the nitro group, allowing charge delocalization onto the nitro oxygens.

As a result of this stabilization, nitronates act as relatively good carbon nucleophiles in organic synthesis. They are weaker acids than many carbanions, with pKa values for nitroalkanes commonly in the mid to high teens in aprotic solvents, so they require strong bases—such as lithium diisopropylamide (LDA), sodium hydride (NaH), or potassium tert-butoxide (KOtBu)—to generate them in situ.

Applications include their central role in the Henry (nitroaldol) reaction, where a nitronate adds to aldehydes or ketones to form β-nitro alcohols after workup. Nitronates can also be alkylated or otherwise transformed to give nitroalkane products upon protonation or further functionalization, making them versatile masked nucleophiles in multistep syntheses.

Derivatives and practical notes: nitronates are often generated in situ under basic conditions and used directly in subsequent transformations. They may be sensitive to acidic conditions, which can protonate the anion and disrupt reactivity. Control of solvent, temperature, and base strength is important to maximize selectivity and yield in nitronate-dependent reactions.