Sodium hydrogenoxalate

Sodium hydrogenoxalate is salt (ionic compound) of formula NaHC
2O
4, consisting of sodium cations Na+
 and hydrogenoxalate anions HC
2O−
4 or HO(O=)C-C(=O)O−
. The anion can be described as the result of removing one hydrogen ion H+
 from oxalic acid H
2C
2O
4, or adding one to the oxalate anion C
2O2−
4.

Sodium hydrogenoxalate
Names
Preferred IUPAC name
Sodium 2-hydroxy-2-oxoacetate
Other names
Ethanedioate, hydrogen sodium salt (1:1:1)
Ethanedioic acid, sodium salt (1:1)
Monosodium oxalate
Sodium hydrogen ethanedioate (1:1:1)
Oxalic acid sodium salt
Oxalic acid, sodium salt
Sodium acid oxalate
Sodium and hydrogen and oxalate
Sodium bioxalate[1]
Identifiers[2][1]
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.013.356
EC Number
  • 214-691-3
UNII
  • InChI=1S/C2H2O4.Na/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+1/p-1
    Key: UJRAXLUXHBUNDO-UHFFFAOYSA-M
  • [Na+].[O-]C(=O)C(=O)O
Properties
C2HNaO4
Molar mass 112.0167[3]
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H312
P264, P270, P280, P301+P312, P302+P352, P312, P322, P330, P363, P501
Related compounds
Other anions
 Sodium bicarbonate (oxalate replaced with carbonate)
Other cations
 Potassium hydrogenoxalate (potassium instead of sodium)
Oxalic acid (hydrogen instead of sodium)
Sodium oxalate (sodium instead of hydrogen)
Related compounds
 Hydrogenoxalate (sodium ion removed)
Oxalate (sodium and hydrogen ions removed)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Properties

Hydrates

The compound is commonly encountered as the anhydrous form or as the monohydrate NaHC
2O
4·H
2O. Both are colorless crystalline solids at ambient temperature.

The monohydrate can be obtained by evaporating a solution of the compound at room temperature.[4]

The crystal structure of NaHC2O4·H2O is triclinic normal (pinacoidal, space group P1). The lattice parameters are a = 650.3 pm, b = 667.3 pm, c = 569.8 pm, α = 85.04°, β = 110.00°, γ = 105.02°, and Z = 2. The hydrogen oxalate ions are linked end to end in infinite chains by hydrogen bonds (257.1 pm). The chains are cross linked to form layers by both O–H···O bonds from the water molecules (280.8 pm, 282.6 pm) and by ionic bonds Na+···O. These layers are in turn held together by Na+···O bonds. The oxalate group is non-planar with an angle of twist about the C–C bond of 12.9°.[5]

Reactions

Upon being heated, sodium hydrogenoxalate converts to oxalic acid and sodium oxalate, the latter of which decomposes into sodium carbonate and carbon monoxide.[6]

2NaHC
2O
4 → Na
2C
2O
4 + H
2C
2O
4
Na
2C
2O
4 → Na
2CO
3 + CO

Toxicity

The health hazards posed by this compound are largely due to its acidity and to the toxic effects of oxalic acid and other oxalate or hydrogenoxalate salts, which can follow ingestion or absorption through the skin. The toxic effects include necrosis of tissues due to sequestration of calcium ions, and the formation of poorly soluble calcium oxalate stones in the kidneys that can obstruct the kidney tubules.[2]

References
  1. "2T9TH558WS: NaHC2O4". ChemSpider website, accessed on 2018-09-11
  2. "Monosodium oxalate". NCBI PubChem website, accessed on 2018-09-11
  3. "Sodium Hydrogen Oxalate NaHC2O4". EndMemo.com website, accessed on 2018-09-11
  4. C. Ramki, R. Ezhil Vizhi (2017): "Growth, optical, electrical and mechanical properties of sodium hydrogen oxalate hydrate (NaHC2O4·H2O) single crystal for NLO applications". Materials Chemistry and Physics, volume 197, pages 70-78. doi:10.1016/j.matchemphys.2017.04.066
  5. Roland Tellgren and Ivar Olovsson (1971): "Hydrogen Bond Studies. XXXXVI. The Crystal Structures of Normal and Deuterated Sodium Hydrogen Oxalate Monohydrate NaHC2O4·H2O and NaDC2O4·D2O". Journal of Chemical Physics, volume 54, issue 1. doi:10.1063/1.1674582
  6. W. Balcerowiak; Cz. Latocha; J. Wasilewski (1980). "Thermoanalytical investigation of mixtures containing oxalic acid, sodium hydrogen oxalate and sodium oxalate". Journal of Thermal Analysis. 18: 57–63. doi:10.1007/BF01909453. S2CID 98061114.


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