Hydrogenoxalate or hydrogen oxalate (IUPAC name: 2-Hydroxy-2-oxoacetate) is an anion with chemical formula HC2O−4 or HO−C(=O)−CO−2, derived from oxalic acid by the loss of a single proton; or, alternatively, from the oxalate anion C2O2−4 by addition of a proton. The name is also used for any salt containing this anion. Especially in older literature, hydrogenoxalates may also be referred to as bioxalates, acid oxalates, or monobasic oxalates. Hydrogenoxalate is amphoteric, in that it can react both as an acid or a base.
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| Names | |
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| IUPAC name
2-Hydroxy-2-oxoacetate[1]
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| Systematic IUPAC name
2-Hydroxy-2-oxoethanoate | |
Other names
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| Identifiers | |
3D model (JSmol)
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| 3601755 | |
| ChEBI | |
| 49515 | |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| HC2O−4 | |
| Molar mass | 89.026 g·mol−1 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Well characterized salts include sodium hydrogenoxalate (NaHC2O4),[2][3] potassium hydrogenoxalate (KHC2O4),[4] ammonium hydrogenoxalate ([NH4]+HC2O−4), rubidium hydrogenoxalate (RbHC2O4)[5] and dimethylammonium hydrogenoxalate ([(CH3)2NH]+HC2O−4).[6]
Structure
editMost hydrogenoxalate salts are hydrated. For example, potassium hydrogen oxalate crystallizes as 2KHC2O4·H2O. These materials exhibit extended structures resulting from extensive hydrogen bonding and anion-cation interactions. The hydrates dehydrate upon heating:[4]
- 2KHC2O4·H2O → 2 KHC2O4 + H2O
Proton transfer in hydrogen oxalates has been studied.[7]
See also
editReferences
edit- ^ "Hydrogen oxalate".
- ^ Tellgren, Roland; Olovsson, Ivar (1971). "The crystal structures of normal and deuterated sodium hydrogen oxalate monohydrate NaHC2O4·H2O and NaDC2O4·D2O. Hydrogen bond studies XXXVI". The Journal of Chemical Physics. 54 (1): 127–134. Bibcode:1971JChPh..54..127T. doi:10.1063/1.1674582.
- ^ Delaplane, R. G.; Tellgren, R.; Olovsson, I. (1984). "Neutron diffraction study of sodium hydrogen oxalate monohydrate, NaHC2O4·H2O, at 120 K". Acta Crystallographica. C40 (11): 1800–1803. Bibcode:1984AcCrC..40.1800D. doi:10.1107/S0108270184009616.
- ^ a b Hume, J.; Colvin, J. (1929). "The decomposition of potassium hydrogen oxalate hemihydrate". Proceedings of the Royal Society of London. Series A, Containing Papers of a Mathematical and Physical Character. 125 (799). The Royal Society: 635–646. Bibcode:1929RSPSA.125..635H. doi:10.1098/rspa.1929.0192. ISSN 0950-1207.
- ^ Hamadène, M.; Kherfi, H.; Guehria-Laidoudi, A. (2006). "The polymeric anhydrous rubidium hydrogen oxalate". Acta Crystallographica. A62: s280. Bibcode:2006AcCrA..62R.280H. doi:10.1107/S0108767306094414.
- ^ Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène (11 April 2015). "Crystal structure of dimethylammonium hydrogen oxalate hemi(oxalic acid)". Acta Crystallographica Section E: Crystallographic Communications. 71 (5). International Union of Crystallography (IUCr): 473–475. Bibcode:2015AcCrE..71..473D. doi:10.1107/s2056989015005964. ISSN 2056-9890. PMC 4420082. PMID 25995858.
- ^ Bosch, Enric; Moreno, Miquel; Lluch, José María (1 January 1992). "The role of coupling in intramolecular proton transfer reactions. The hydrogen oxalate anion as an example". Canadian Journal of Chemistry. 70 (1). Canadian Science Publishing: 100–106. doi:10.1139/v92-017. ISSN 0008-4042.