Magnesium oxalate

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Magnesium oxalate
Magnesium oxalate.svg
IUPAC name
magnesium oxalate
Systematic IUPAC name
magnesium oxalate
Other names
  • magnesium ethanedioate
  • ethanedioic acid, magnesium salt (1:1)
  • (Dihydrate)
  • magnesium oxalate-2-hydrate
  • magnesium oxalate dihydrate
  • oxalic acid magnesium salt dihydrate
3D model (JSmol)
ECHA InfoCard 100.008.121 OOjs UI icon edit-ltr-progressive.svg
EC Number
PubChem CID
UN number 2811 [4]
  • InChI=
    • 1S/C2H2O4.Mg/c3-1(4)2(5)6;/h(H,3,4)(H,5,6);/q;+2/p-2
    • 1S/C2H2O4.Mg.2H2O/c3-1(4)2(5)6;;;/h(H,3,4)(H,5,6);;2*1H2/q;+2;;/p-2 (Dihydrate)
    [5] [6]
  • C(=O)(C(=O)[O-])[O-].[Mg+2]
  • MgC2O4
  • MgC2O4•2H2O (Dihydrate)
Molar mass
  • 112.324 g/mol
  • 148.354 g/mol (Dihydrate)
Appearancewhite solid [2]
Density 2.45 g/cm3 [5]
Melting point between 420 and 620 °C (788 and 1,148 °F; 693 and 893 K)
150 °C (302 °F; 423 K) (dihydrate)both decompose [7]
Boiling point Not Applicable
0.038g/100g H2O (anhydrous and dihydrate) [2]
8.5 × 10−5 for MgC
Solubility insoluble in organics
Vapor pressure 2.51×10−6 mmHg [3]
-1269.0 kJ mol−1 [2]
Occupational safety and health (OHS/OSH):
Main hazards
NFPA 704 (fire diamond)
Flash point Not Applicable
Not Applicable
Related compounds
Related compounds
Magnesium Oxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Magnesium oxalate is an organic compound comprising a magnesium cation with a 2+ charge bonded to an oxalate anion. It has the chemical formula MgC2O4. Magnesium oxalate is a white solid that comes in two forms: an anhydrous form and a dihydrate 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 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. [9]

Synthesis and reactions

Magnesium oxalate can by synthesized by combining a magnesium salt or ion with an oxalate.

Mg2+ + C2O42− → MgC2O4

A specific example of a synthesis would be mixing Mg(NO3)2 and KOH and then adding that solution to dimethyl oxalate, (COOCH3)2. [10]

When heated, magnesium oxalate will decompose. First, the dihydrate will decompose at 150 °C into the anhydrous form.

MgC2O4•2H2O → MgC2O4 + 2 H2O

With additional heating the anhydrous form will decompose further into magnesium oxide and carbon oxides between 420 °C and 620 °C. First, carbon monoxide and magnesium carbonate form. The carbon monoxide then oxidizes to carbon dioxide, and the magnesium carbonate decomposes further to magnesium oxide and carbon dioxide. [7]

MgC2O4 → MgCO3 + CO
CO + 1/2 O2 → CO2
MgCO3 → 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. 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. [11]

Health and safety

Magnesium oxalate is a skin and eye irritant. If inhaled, it will irritate the lungs and mucous membranes. 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. [4] [12]

See also

Related Research Articles

Alkaline earth metal Group of chemical elements

The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.

Sodium carbonate Chemical compound

Sodium carbonate, Na2CO3·10H2O, (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield moderately alkaline solutions in water. Historically, it was extracted from the ashes of plants growing in sodium-rich soils. Because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process.

Calcium oxalate Calcium compound

Calcium oxalate (in archaic terminology, oxalate of lime) is a calcium salt of oxalic acid with the chemical formula CaC2O4. It forms hydrates CaC2O4·nH2O, where n varies from 1 to 3. Anhydrous and all hydrated forms are colorless or white. The monohydrate CaC2O4·H2O occurs naturally as the mineral whewellite, forming envelope-shaped crystals, known in plants as raphides. The two rarer hydrates are dihydrate CaC2O4·2H2O, which occurs naturally as the mineral weddellite, and trihydrate CaC2O4·3H2O, which occurs naturally as the mineral caoxite, are also recognized. Some foods have high quantities of calcium oxalates and can produce sores and numbing on ingestion and may even be fatal. Tribes with diets that depend highly on fruits and vegetables high in calcium oxalate, such as in Micronesia, reduce the level of it by boiling and cooking them. They are a constituent in 76% of human kidney stones. Calcium oxalate is also found in beerstone, a scale that forms on containers used in breweries.

Magnesium sulfate Chemical compound with formula MgSO4

Magnesium sulfate or magnesium sulphate (in English-speaking countries other than the US) is a chemical compound, a salt with the formula MgSO4, consisting of magnesium cations Mg2+ (20.19% by mass) and sulfate anions SO2−4. It is a white crystalline solid, soluble in water but not in ethanol.

Magnesium carbonate Chemical compound

Magnesium carbonate, MgCO3, is an inorganic salt that is a colourless or white solid. Several hydrated and basic forms of magnesium carbonate also exist as minerals.

Oxalic acid Simplest dicarboxylic acid

Oxalic acid is an organic acid with the IUPAC name ethanedioic acid and formula HO2C−CO2H. 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 investigators isolated oxalic acid from flowering plants of the genus Oxalis, commonly known as wood-sorrels. It occurs naturally in many foods, but excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.

A pyrotechnic colorant is a chemical compound which causes a flame to burn with a particular color. These are used to create the colors in pyrotechnic compositions like fireworks and colored fires. The color-producing species are usually created from other chemicals during the reaction. Metal salts are commonly used; elemental metals are used rarely.

Gadolinium(III) oxide Chemical compound

Gadolinium(III) oxide (archaically gadolinia) is an inorganic compound with the formula Gd2O3. It is one of the most commonly available forms of the rare-earth element gadolinium, derivatives of which are potential contrast agents for magnetic resonance imaging.

Potassium ferrioxalate Chemical compound

Potassium ferrioxalate, also called potassium trisoxalatoferrate or potassium tris(oxalato)ferrate(III) is a chemical compound with the formula K
]. It often occurs as the trihydrate K3[Fe(C2O4)3]·3H2O. Both are crystalline compounds, lime green in colour.

Magnesium iodide Chemical compound

Magnesium iodide is the name for the chemical compounds with the formulas MgI2 and its various hydrates MgI2(H2O)x. These salts are typical ionic halides, being highly soluble in water.

Iron(II) oxalate Chemical compound

Ferrous oxalate, or iron(II) oxalate, is an inorganic compound with the formula FeC2O4 · xH2O where x is typically 2. These are orange compounds, poorly soluble in water.

The carbonite ion is the double ionized ion of dihydroxymethylidene, with the chemical formula: CO2−
. Alkali metal salts, such as Li
, K
, and Cs
, have been observed at 15 K. Due to the lone pair on the carbon atom, salts of the carbonite ion would be protonated to form formate and formic acid, rather than the carbene.

Strontium oxalate Chemical compound

Strontium oxalate is a compound with the chemical formula SrC2O4. Strontium oxalate can exist either in a hydrated form (SrC2O4nH2O) or as the acidic salt of strontium oxalate (SrC2O4mH2C2O4nH2O).

Chromium(II) oxalate is an inorganic compound with the chemical formula CrC2O4.

Mesoporous magnesium carbonate

Mesoporous magnesium carbonates (MMCs) constitute a family of magnesium carbonate materials with high specific surface areas. It was first reported in July 2013 by a group of researchers in nanotechnology at Uppsala University. The highest reported surface area of any MMC is 800 m² per gram, which is the highest surface area ever measured for an alkali earth metal carbonate. The average pore size of MMCs can be adjusted by tuning the synthesis conditions. So far, all reported forms of MMCs are anhydrous and X-ray amorphous.

Magnesium oxychloride is the traditional term for several chemical compounds of magnesium, chlorine, oxygen, and hydrogen whose general formula xMgO·yMgCl
, for various values of x, y, and z; or, equivalently, Mg
. Other names for this class are magnesium chloride hydroxide, magnesium hydroxychloride, and basic magnesium chloride. Some of these compounds are major components of Sorel cement.

Praseodymium (III,IV) oxide is the inorganic compound with the formula Pr6O11 that is insoluble in water. It has a cubic fluorite structure. It is the most stable form of praseodymium oxide at ambient temperature and pressure.

Caesium oxalate (standard IUPAC spelling) dicesium oxalate, or cesium oxalate (American spelling) is the oxalate of caesium. Caesium oxalate has the chemical formula of Cs2C2O4.

The nickel organic acid salts are organic acid salts of nickel. In many of these the ionised organic acid acts as a ligand.

The carbonate oxalates are mixed anion compounds that contain both carbonate (CO3) and oxalate (C2O4) anions. Most compounds incorporate large trivalent metal ions, such as the rare earth elements. Some carbonate oxalate compounds of variable composition are formed by heating oxalates.


  1. 1 2 3 "Oxalates-Compound Summary" . Retrieved 16 November 2012.
  2. 1 2 3 4 5 6 7 CRC Handbook of Chemistry and Physics (93 ed.). 2012–2013.
  3. 1 2 "Magnesium Oxalate Chemical Formula, Chemical CAS 547-66-0" . Retrieved 16 November 2012.
  4. 1 2 "Magnesium Oxalate". Archived from the original on 20 February 2014. Retrieved 16 November 2012.
  5. 1 2 "Magnesium Oxalate" . Retrieved 16 November 2012.
  6. "Magnesium Oxalate" . Retrieved 16 November 2012.
  7. 1 2 Gadala, Ahmed (1984). "Kinetics of the Decomposition of Hydrated Oxalates of Calcium and Magnesium in Air". Thermochimica Acta. 74 (1–3): 255–272. doi:10.1016/0040-6031(84)80027-1.
  8. Euler. "Ksp Table: Solubility product constants near 25 °C". Retrieved 10 June 2021.
  9. Wilson, M; D. Jones; D.J. Russell (1980). "Glushinskite, a naturally occurring magnesium oxalate". Mineralogical Magazine. 43 (331): 837–840. doi:10.1180/minmag.1980.043.331.02.
  10. Masuda, Yoshio (1987). "Kinetics of the Thermal Dehydration of Magnesium Oxalate Dihydrate in a Flowing Atmosphere of Dry Nitrogen". J. Phys. Chem. 91 (26): 6543–6547. doi:10.1021/j100310a024.
  11. Mastuli, Mohd; Roshidah Rusdi; Annie Mahat; Norazira Saat; Norlida Kamarulzaman (2012). "Sol-Gel Synthesis of Highly Stable Nano Sized MgO from Magnesium Oxalate Dihydrate". Advanced Materials Research. 545: 137–142. doi:10.4028/ S2CID   97071145.
  12. "Material Safety Data Sheet Magnesium Oxalate" . Retrieved 16 November 2012.