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
EC Number 208-932-1[3]
UN number 2811 [4]
  • MgC2O4
  • MgC2O4•2H2O (Dihydrate)
Molar mass
  • 112.324 g/mol
  • 148.354 g/mol (Dihydrate)
Appearance white 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]
Solubility insoluble in organics
Vapor pressure 2.51×10−6 mmHg[3]
-1269.0 kJ mol−1[2]
Main hazards Irritant
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored 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).
Infobox references

Magnesium oxalate is an inorganic 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[edit]

Some oxalates can be found in nature and the most known naturally occurring oxalates are whewellite and weddellite, which are calcium oxalates. Magnesium oxalate has been found naturally near Mill of Johnston which is located close to Insch in northeast Scotland. The naturally occurring magnesium oxalate is called glushinskite. The magnesium oxalate was found at the lichen and rock interface on serpentinite. It was found in a creamy white layer which was mixed in with 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.[8]

Synthesis and reactions[edit]

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 (COOCH3)2.[9] Magnesium oxalate when heated will decompose. First, the dihydrate will decompose at 150 °C into the anhydrous form.

MgC2O4•2H2O → MgC2O4 + 2H2O

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 + 1/2O2 → CO2
MgCO3 → MgO + CO2

Magnesium oxalate dihydrate has also been used in the synthesis of nano sized magnesium oxide. Magnesium oxide is important because it is used as a catalyst, refractory materials, adsorbents, superconductors, and ferroelectric materials. Nano sized particles of magnesium oxide are optimal for some of these uses because of the larger surface area to volume ratio as compared with larger particles. Most common syntheses of magnesium oxide produce fairly large particles, however, the sol-gel synthesis using magnesium oxalate produces highly stable nano sized particles of magnesium oxide. The sol-gel synthesis involves combining a magnesium salt, or in this case magnesium oxalate, with a gelating agent. This process effectively produces nano sized particles of magnesium oxide.[10]

Health and safety[edit]

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. If magnesium oxalate does come in contact with skin or eyes, flush with water for at least 15 minutes and call a physician if irritation occurs. If inhaled, go to fresh air and call a physician. If swallowed, call a physician immediately. If a spill occurs wash with water and make sure that no dust is released into the air. Dispose of the wash water accordingly. Whenever working with magnesium oxalate, safety goggles, boots, and a lab apron should be worn. If there is dust in the air, a respirator should be worn also. 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][11]


  1. ^ a b c "Oxalates-Compound Summary". Retrieved 16 November 2012. 
  2. ^ a b c d e f CRC Handbook of Chemistry and Physics (93 ed.). 2012–2013. 
  3. ^ a b "Magnesium Oxalate Chemical Formula, Chemical CAS 547-66-0". Retrieved 16 November 2012. 
  4. ^ a b "Magnesium Oxalate". Retrieved 16 November 2012. 
  5. ^ a b "Magnesium Oxalate". Retrieved 16 November 2012. 
  6. ^ "Magnesium Oxalate". Retrieved 16 November 2012. 
  7. ^ a b Gadala, Ahmed (1984). "Kinetics of the Decomposition of Hydrated Oxalates of Calcium and Magnesium in Air". Thermochimica Acta. 74: 255–272. doi:10.1016/0040-6031(84)80027-1. 
  8. ^ Wilson, M; D. Jones; D.J. Russell (1980). "Glushinskite, a naturally occurring magnesium oxalate". Mineralogical Magazine. 43: 837–840. doi:10.1180/minmag.1980.043.331.02. 
  9. ^ Masuda, Yoshio (1987). "Kinetics of the Thermal Dehydration of Magnesium Oxalate Dihydrate in a Flowing Atmosphere of Dry Nitrogen". J. Phys. Chem. 91: 6543–6547. doi:10.1021/j100310a024. 
  10. ^ 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/ 
  11. ^ "Material Safety Data Sheet Magnesium Oxalate". Retrieved 16 November 2012. 

See also[edit]