Ammonium oxalate structure, properties and uses

2023
Anthony Golden

The ammonium oxalate It is a salt of ammonium and oxalic acid that combine in a 2: 1 ratio. It is produced from a neutralization reaction in water of oxalic acid, HtwoCtwoOR4, with ammonium carbonate or ammonium hydroxide. In the first case, CO is producedtwo secondarily.

Its molecular formula is CtwoH8NtwoOR4, but this is commonly written as (NH4)twoCtwoOR4. It is produced biologically in vertebrate animals, starting from the metabolism of glyoxylic acid or ascorbic acid.

Source: Vidak [Public domain], via Wikimedia Commons

Ammonium oxalate may be present in some types of kidney stones, although the greater proportion of oxalate kidney stones, it is found in combination with calcium, forming calcium oxalate..

It cannot be metabolized in the human body, but it can be absorbed from the intestine and excreted in the feces. It can also be eliminated from the human body through urine..

In nature, it is found in the mineral oxammite, which is considered a very scarce and rare mineral. In addition, it is present in guano: a product of the decomposition of the feces of seabirds, bats and seals in a very arid environment. Guano, due to its richness in nitrogen, has been used as a fertilizer and fungicide for plants.

Article index

  • 1 Chemical structure
  • 2 Physical and chemical properties
    • 2.1 Physical appearance
    • 2.2 Molecular formula
    • 2.3 Anhydrous molecular weight
    • 2.4 Melting point
    • 2.5 Boiling point
    • 2.6 Solubility in water
    • 2.7 Solubility in organic solvents
    • 2.8 Density
    • 2.9 Vapor pressure
    • 2.10 pH
    • 2.11 Decomposition
  • 3 Uses
    • 3.1 Industrial
    • 3.2 Wintrobe's reagent
    • 3.3 Biological and analytical
  • 4 Risks in its use
  • 5 References 

Chemical structure

Source: Edgar181 via Wikipedia

The upper image shows the structures of the ions that make up ammonium oxalate. Although it is not appreciated, the NH4+ consists of a tetrahedron, while the CtwoOR4two- has a flat structure due to sp hybridizationtwo of all its carbon atoms.

Its chemical formula, (NH4)twoCtwoOR4, indicates that there must be two NH4+ interacting electrostatically with a CtwoOR4two-; that is, two tetrahedra around a plane.

In addition to ionic bonding, ions are capable of forming multiple hydrogen bonds; NH4+ donates them, and the CtwoOR4two- accepts them (through its four oxygens).

As there is a high possibility that a molecule also forms hydrogen bonds with one of the ions, it intercalates giving rise to (NH4)twoCtwoOR4∙ HtwoOR.

Crystals are made up of millions of ions and unit cells, in which the 2NH ratio is fulfilled.4/1 CtwoOR4 just named.

This being the case, in a crystal of (NH4)twoCtwoOR4∙ HtwoOr an orthorhombic crystal arrangement is formed, where hydrogen bonds play a crucial role in its physical properties..

Observing its crystalline structure from a frontal plane, NH4+ form a phase, while the CtwoOR4two- and HtwoOr they form another phase; rows of tetrahedra separated by planes and angular molecules (water).

Physical and chemical properties

Physical appearance

Solid white.

Molecular formula

CtwoH8NtwoOR4

Anhydrous molecular weight

124.096 g / mol.

Melting point

70ºC (158ºF), as it appears on Wikipedia. However, Chemspider and Softschools indicate a melting point between 131 and 135 ºC.

Meanwhile, Pubchem indicates that the decomposition of the compound occurs at 70 ºC, making it unlikely that a melting point higher than this temperature can be found..

Boiling point

Indeterminate by compound decomposition.

Water solubility

5.1 g / 100 mL of water at 20 ºC. Ammonium oxalate slowly dissolves in water and often sinks in.

Solubility in organic solvents

Slightly soluble in alcohols and insoluble in ammonia.

Density

1.5 g / cm3 at 65.3ºF.

Vapor pressure

0 mmHg at 20 ºC.

pH

Between 6 and 7 in a 4% solution at 25 ° C.

Decomposition

When exposed to high temperatures, it decomposes, emitting a toxic and corrosive smoke that includes ammonium and nitrogen oxides..

Applications

Industrial

-It is used in the manufacture of explosives

-Serves as electrolytic destaining of iron

-Allows to polish the surface of metals.

Recently, pectins have been extracted with ammonium oxalate, for the manufacture of food gelling agents.

Wintrobe reagent

It is used in combination with potassium oxalate to form Wintrobe's reagent, which is used as an anticoagulant..

The reagent is a mixture of 1.2 g of ammonium oxalate with 0.8 g of potassium oxalate and 0.5 mL of formaldehyde, making up to 100 mL with water..

Biological and analytical

-The ammonium salt increases the volume of erythrocytes, while the potassium salt decreases it. Therefore, their effect on erythrocytes is compensated, guaranteeing their morphological integrity. This system exerts its anticoagulant action by sequestering the calcium ion.

-Ammonium oxalate is used as an analytical reagent and reducing agent, being used in the quantification of the plasma concentration of calcium and lead. In addition, ammonium oxalate is used as a dispersing agent in the study of platelet surface interactions..

-It also integrates a pH buffer system.

Risks in its use

-Direct contact with the skin and eyes can cause irritation and burns. Likewise, prolonged or repetitive skin contact with the compound can cause signs such as: rashes, dryness and redness..

-Inhalation can irritate the nose, throat and lungs. Repeated exposure could cause bronchitis with cough, phlegm, and shortness of breath..

-High exposure to this salt can cause headache, dizziness, nausea, vomiting, seizures, coma, and even death..

-Ingestion or excessive inhalation causes systemic poisoning. Possible symptoms include pain in the throat, esophagus, and stomach. The mucosal membranes turn white, there are severe diarrhea, weak pulse, cardiovascular and neuromuscular collapse. In addition, it can affect kidney function and calcium balance..

-Calcium is involved in numerous processes that occur in living beings, among them: it mediates muscle contraction, both in smooth and striated muscles; intervenes at synapses in neuromuscular transmission; it is essential in various stages of the coagulation cascade; regulates ionic permeability and conductance in membranes, etc..

Therefore, by sequestering the ammonium oxalate to the calcium ion, the performance of the essential functions for life is compromised..

References

  1. Wikipedia. (2018). Ammonium oxalate. Recovered from: en.wikipedia.org
  2. Growth and characterization of ammonium oxalate monohydrate single crystals. [PDF]. Recovered from: shodhganga.inflibnet.ac.in
  3. Qiao Y., Wang K., Yuan H., & Yang K. (2015). Negative Linear Compressibility in Organic Mineral Ammonium Oxalate Monohydrate with Hydrogen Bonding Wine-Rack Motifs. Journal of Physical Chemistry Letters 6 (14): 2755-60
  4. PubChem. (2018). Ammonium Oxalate. Recovered from: pubchem.ncbi.nlm.nih.gov
  5. Royal Society of Chemistry. (2015). Ammonium oxalate. ChemSpider. Recovered from: chemspider.com
  6. Softschools. (2018). Normality formula. Recovered from: softschools.com
  7. Winkler. (s.f.). Chemical safety data sheet: Ammonium oxalate 1-hydrate. Recovered from: iio.ens.uabc.mx
  8. NJ Health. (s.f.). Ammonium oxalate. [PDF]. Recovered from: nj.gov

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