Magnesium oxalate is an

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. T ...

comprising a

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

cation with a 2+ charge bonded to an

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 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 ...

. It has the chemical formula MgCO. Magnesium oxalate is a white solid that comes in two forms: an anhydrous form and a

dihydrate In chemistry, a hydrate is a substance that contains water or its constituent elements. The chemical state of the water varies widely between different classes of hydrates, some of which were so labeled before their chemical structure was understo ...

form where two water molecules are complexed with the structure. Both forms are practically insoluble in water and are insoluble in organic solutions.

Natural occurrence

Magnesium oxalate has been found naturally near Mill of Johnston, which is located close to Insch in northeast Scotland. This naturally occurring magnesium oxalate is called glushinskite and occurs at the lichen/rock interface on

serpentinite Serpentinite is a rock composed predominantly of one or more serpentine group minerals, the name originating from the similarity of the texture of the rock to that of the skin of a snake. Serpentinite has been called ''serpentine'' or ''se ...

as a creamy white layer mixed in with the hyphae of the lichen fungus. A scanning electron micrograph of samples taken showed that the crystals had a pyramidal structure with both curved and striated faces. The size of these crystals ranged from 2 to 5 μm.

Synthesis and reactions

Magnesium oxalate can by synthesized by combining a magnesium salt or ion with an oxalate. : Mg²⁺ + CO²⁻ → MgCO A specific example of a synthesis would be mixing Mg(NO₃)₂ and KOH and then adding that solution to

dimethyl oxalate Dimethyl oxalate is the organic compound with the formula (CO2CH3)2. It is the dimethyl ester of oxalic acid. Dimethyl oxalate is a colorless or white solid that is soluble in water. Production Dimethyl oxalate can be obtained by esterificatio ...

, (COOCH₃)₂. When heated, magnesium oxalate will decompose. First, the dihydrate will decompose at 150 °C into the anhydrous form. : MgCO•2H₂O → MgCO + 2 H₂O With additional heating the anhydrous form will decompose further into

magnesium oxide Magnesium oxide ( Mg O), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

and carbon oxides between 420 °C and 620 °C. First,

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 simple ...

and magnesium carbonate form. The carbon monoxide then oxidizes to

carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...

, and the magnesium carbonate decomposes further to magnesium oxide and carbon dioxide. : MgCO → MgCO + CO : CO + 1/2 O₂ → CO₂ : MgCO → MgO + CO₂ Magnesium oxalate dihydrate has also been used in the synthesis of nano sized particles of magnesium oxide, which have larger surface are to volume ratio than conventionally synthesized particles and are optimal for various applications, such as in

catalysis Catalysis () is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst (). Catalysts are not consumed in the reaction and remain unchanged after it. If the reaction is rapid and the catalyst recyc ...

. By using a sol-gel synthesis, which involves combining a magnesium salt, in this case magnesium oxalate, with a gelating agent, nano sized particles of magnesium oxide can be produced.

Health and safety

Magnesium oxalate is a skin and eye irritant. If inhaled, it will irritate the lungs and

mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It i ...

s. Magnesium oxalate has no known chronic effects nor any carcinogenic effects. Magnesium oxalate is non-flammable and stable, but in fire conditions it will give off toxic fumes. According to OSHA, magnesium oxalate is considered to be hazardous.

References

{{DEFAULTSORT:Magnesium oxalate Oxalates Magnesium compounds Inorganic compounds

Natural occurrence

Synthesis and reactions

Health and safety

See also

References