A nitronate (IUPAC: azinate) in organic chemistry is a functional group with the general structure R1R2C=NO−
2. It is the anion of nitronic acid (sometimes also called an aci, or an azinic acid), a tautomeric form of a nitro compound. Just as ketones and aldehydes can exist in equilibrium with their enol tautomer, nitro compounds exist in equilibrium with their nitronate tautomer under basic conditions. In practice they are formed by the deprotonation of the α-carbon, the pka of which is typically around 17.
Nitronates are formed as intermediates in the Henry reaction and Nef reaction, the later of which also demonstrates the instability of the nitronic acid form. The nitronate has two different resonance structures, one with a negative charge on the α-carbon and a double bond between the nitrogen and one of the oxygens, and another resonance structure with a double bond between the nitrogen and the α carbon, and no double bond between the nitrogen and the oxygens.
- Breuer, Eli; Aurich, Hans Günter; Nielsen, Arnold. Nitrones, nitronates, and nitroxides. Wiley. ISBN 9780470772195. doi:10.1002/9780470772195
- F. A. Carey, R. J. Sundberg (2004). Organische Chemie. Wiley-VCH Verlag. ISBN 3-527-29217-9.
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "aci-nitro compounds". doi:10.1351/goldbook.A00085
- IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") (1997). Online corrected version: (2006–) "azinic acids". doi:10.1351/goldbook.A00558