Sodium hydrogenoxalate is salt (ionic compound) of formula , consisting of sodium

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

s and

hydrogenoxalate Hydrogenoxalate or hydrogen oxalate is an anion with chemical formula or , derived from oxalic acid by the loss of a single proton; or, alternatively, from the oxalate anion by addition of a proton. The name is also used for any salt containing ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

s or . The anion can be described as the result of removing one

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

from

oxalic acid Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula . It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early inve ...

, or adding one to the

oxalate Oxalate (IUPAC: ethanedioate) is an anion with the formula C2O42−. This dianion is colorless. It occurs naturally, including in some foods. It forms a variety of salts, for example sodium oxalate (Na2C2O4), and several esters such as dimethyl ...

anion .

Properties

Hydrates

The compound is commonly encountered as the

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...

form or as the mono hydrate ·. Both are colorless crystalline solids at ambient temperature. The monohydrate can be obtained by evaporating a solution of the compound at room temperature.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. The crystal structure of NaHC₂O₄·H₂O is triclinic normal (pinacoidal,

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it ...

''P''). The

lattice parameter A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has o ...

s 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°.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.

Reactions

Upon being heated, sodium hydrogenoxalate converts to

and

sodium oxalate Sodium oxalate, or disodium oxalate, is the sodium salt of oxalic acid with the formula Na2C2O4. It is a white, crystalline, odorless solid, that decomposes above 290 °C. Disodium oxalate can act as a reducing agent, and it may be used as a pr ...

, the latter of which decomposes into sodium carbonate and

carbon monoxide Carbon monoxide ( chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

. :2 → + : → +

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 Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dig ...

of tissues due to sequestration of

calcium Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...

ions, and the formation of poorly soluble

calcium oxalate Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula . It forms hydrates , where ''n'' varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate ...

stones in the

kidney The kidneys are two reddish-brown bean-shaped organs found in vertebrates. They are located on the left and right in the retroperitoneal space, and in adult humans are about in length. They receive blood from the paired renal arteries; bloo ...

s that can obstruct the

kidney tubule The nephron is the minute or microscopic structural and functional unit of the kidney. It is composed of a renal corpuscle and a renal tubule. The renal corpuscle consists of a tuft of capillaries called a glomerulus and a cup-shaped structure ca ...

References

Organic sodium salts Oxalates Carboxylate anions {{chemistry-stub